Sample records for hafnium carbide four-foot

  1. Hafnium

    SciTech Connect (OSTI)

    NONE

    1994-02-01T23:59:59.000Z

    Having been predicted from atomic number sequence, it was the first element to be discovered by X-ray methods in 1923, following spectroscopic examination of zirconium minerals by D. Coster and G. C. de Hevesey. Hafnium derives its name from {open_quotes}Hafnia{close_quotes}, the Latin name for Copenhagen. The crustal abundance of hafnium is estimated at 2.8-4.5 ppm. The element hafnium is commonly found only in solid solution with zirconium in various zirconium ores, and is a by-product of zirconium metal production. The major commercial mineral source of hafnium is zircon; a minor source is baddeleyite. Zircon, typically 67% zirconium plus hafnium oxides, is found in alluvial or beach deposits together with other heavy minerals such as rutile and ilmenite. The ratio of zirconium to hafnium in zircon averages about 50:1. Recovery is accomplished by mining, dredging on scraping, followed by wet concentration by gravity processing and then dry separation, usually by magnetic or electrostatic processes. The zirconium/hafnium concentrate is separated by liquid-liquid extraction using methyl isobutyl ketone, or extractive distillation to produce hafnium oxide. Hafnium sponge is produced by reacting the oxide with chlorine in a fluid bed chlorinator, followed by a {open_quotes}Kroll-type{close_quotes} reaction. Additional refining of the metal is possible by electrofining, electron beam melting, or the iodide process. Refined hafnium metal is regularly referred to as {open_quotes}crystal bar hafnium-iodide metal{close_quotes}, or ductile hafnium.

  2. Definition of prominent thermal mechanisms associated with the buoyancy-induced transport of hafnium-carbide within a solidifying uranium-hafnium alloy

    SciTech Connect (OSTI)

    Taylor, M.J. (Oak Ridge K-25 Site, TN (United States)); Mackiewicz-Ludtka, G. (Oak Ridge Y-12 Plant, TN (United States))

    1992-12-01T23:59:59.000Z

    Environmental concerns over uranium wastes generated interest in using existing uranium stockpiles as feed materials. One obstacle to recycling is accumulation of carbon that can degrade as-cast mechanical properties. A program was begun to develop a casting procedure capable of reducing the C content in components made from recycled uranium to levels comparable with virgin feed stock. Trace amounts of Hf are added to form low-density Hf C, which floats to the top of the casting, and can be removed at a later time. Developing this procedure requires modeling carbide transport within solidifying uranium, and this necessitates solving a coupled, nonlinear fluid dynamics, heat transfer, and solution thermodynamics problem. The heat transfer facet was addressed first. Steady-state and transient thermal performance of a laboratory-scale casting assembly was characterized to identify those mechanisms that have a prominent influence on modeling uranium melt solidification. The analysis showed that (1) at least first-order accurate definitions for all thermal mechanisms were required to obtain meaningful agreement with experimental data; (2) prominent mechanisms were thermal contact resistances, liquid uranium natural convection, and internal heat generation; and (3) accurately modeling assembly geometry and enclosure radiation heat transfer would also improve agreement. It was recommended that a second-generation thermal model should be constructed which would include each of these elements.

  3. Silver-hafnium braze alloy

    DOE Patents [OSTI]

    Stephens Jr., John J.; Hosking, F. Michael; Yost, Frederick G.

    2003-12-16T23:59:59.000Z

    A binary allow braze composition has been prepared and used in a bonded article of ceramic-ceramic and ceramic-metal materials. The braze composition comprises greater than approximately 95 wt % silver, greater than approximately 2 wt % hafnium and less than approximately 4.1 wt % hafnium, and less than approximately 0.2 wt % trace elements. The binary braze alloy is used to join a ceramic material to another ceramic material or a ceramic material, such as alumina, quartz, aluminum nitride, silicon nitride, silicon carbide, and mullite, to a metal material, such as iron-based metals, cobalt-based metals, nickel-based metals, molybdenum-based metals, tungsten-based metals, niobium-based metals, and tantalum-based metals. A hermetic bonded article is obtained with a strength greater than 10,000 psi.

  4. ZIRCONIUM AND HAFNIUM--1998 86.1 ZIRCONIUM AND HAFNIUM

    E-Print Network [OSTI]

    and tables were prepared by Imogene P. Bynum, statistical officer, and the world production table Berzelius produced the first impure zirconium metal in 1824. Commercial metal production is by reduction by passing hafnium tetrachloride over a tungsten filament in 1925 (van Arkel and de Boer, 1925). Commercial

  5. Formulation and method for preparing gels comprising hydrous hafnium oxide

    DOE Patents [OSTI]

    Collins, Jack L; Hunt, Rodney D; Montgomery, Frederick C

    2013-08-06T23:59:59.000Z

    Formulations useful for preparing hydrous hafnium oxide gels contain a metal salt including hafnium, an acid, an organic base, and a complexing agent. Methods for preparing gels containing hydrous hafnium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including hafnium, an acid, an organic base, and a complexing agent.

  6. Zirconium and hafnium separation at Y-12

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and hafnium separation at Y-12 When then Captain Hyman G. Rickover completed his nuclear reactor training at the Clinton Laboratories in 1947, he quickly saw the advantage of using...

  7. Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments

    E-Print Network [OSTI]

    Danon, Yaron

    the time-of-flight technique. Lithium-6 glass scintillation detectors were used for transmission for natural hafnium, it did affect the way the hafnium interactions would change with exposure to a neutron

  8. 2006 Minerals Yearbook ZIRCONIUM AND HAFNIUM

    E-Print Network [OSTI]

    .S. Geological Survey from a voluntary survey of domestic operations. Of the 44 operations surveyed, 31 did concentrates are developed by a second voluntary survey of domestic mining operations. Of the two domestic2006 Minerals Yearbook ZIRCONIUM AND HAFNIUM U.S. Department of the Interior U.S. Geological Survey

  9. Carbide and carbonitride surface treatment method for refractory metals

    DOE Patents [OSTI]

    Meyer, G.A.; Schildbach, M.A.

    1996-12-03T23:59:59.000Z

    A carbide and carbonitride surface treatment method for refractory metals is provided, in steps including, heating a part formed of boron, chromium, hafnium, molybdenum, niobium, tantalum, titanium, tungsten or zirconium, or alloys thereof, in an evacuated chamber and then introducing reaction gases including nitrogen and hydrogen, either in elemental or water vapor form, which react with a source of elemental carbon to form carbon-containing gaseous reactants which then react with the metal part to form the desired surface layer. Apparatus for practicing the method is also provided, in the form of a carbide and carbonitride surface treatment system including a reaction chamber, a source of elemental carbon, a heating subassembly and a source of reaction gases. Alternative methods of providing the elemental carbon and the reaction gases are provided, as well as methods of supporting the metal part, evacuating the chamber with a vacuum subassembly and heating all of the components to the desired temperature. 5 figs.

  10. ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)

    E-Print Network [OSTI]

    concentrates: Australia, 48%; South Africa, 47%; and other, 5%. Zirconium, unwrought, including powder: France, 51%; Germany, 10%; United Kingdom, 10%; South Africa, 9%; and other, 20%. Hafnium, unwrought: France. The leading consumers of zirconium metal and hafnium metal are the nuclear energy and chemical process

  11. ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)

    E-Print Network [OSTI]

    consumers of zirconium and hafnium metal are the nuclear energy and chemical process industries. Salient during metal production and fabrication and was recycled by companies in Oregon and Utah. Scrap zirconium. Zirconium and hafnium metal were produced from zircon by two domestic producers, one in Oregon and the other

  12. ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)

    E-Print Network [OSTI]

    @usgs.gov, fax: (703) 648-7757] #12;187 ZIRCONIUM AND HAFNIUM Events, Trends, and Issues: Domestic consumption coatings, and sandblasting. The leading consumers of zirconium and hafnium metal are the nuclear energy,080 2,300 Zirconium oxide1 2,260 3,340 2,400 2,970 1,700 Consumption, zirconium ores and concentrates

  13. Microwave sintering of boron carbide

    DOE Patents [OSTI]

    Blake, R.D.; Katz, J.D.; Petrovic, J.J.; Sheinberg, H.

    1988-06-10T23:59:59.000Z

    A method for forming boron carbide into a particular shape and densifying the green boron carbide shape. Boron carbide in powder form is pressed into a green shape and then sintered, using a microwave oven, to obtain a dense boron carbide body. Densities of greater than 95% of theoretical density have been obtained. 1 tab.

  14. Carbide and carbonitride surface treatment method for refractory metals

    DOE Patents [OSTI]

    Meyer, Glenn A. (Danville, CA); Schildbach, Marcus A. (Livermore, CA)

    1996-01-01T23:59:59.000Z

    A carbide and carbonitride surface treatment method for refractory metals is provided, in steps including, heating a part formed of boron, chromium, hafnium, molybdenum, niobium, tantalum, titanium, tungsten or zirconium, or alloys thereof, in an evacuated chamber and then introducing reaction gases including nitrogen and hydrogen, either in elemental or water vapor form, which react with a source of elemental carbon to form carbon-containing gaseous reactants which then react with the metal part to form the desired surface layer. Apparatus for practicing the method is also provided, in the form of a carbide and carbonitride surface treatment system (10) including a reaction chamber (14), a source of elemental carbon (17), a heating subassembly (20) and a source of reaction gases (23). Alternative methods of providing the elemental carbon (17) and the reaction gases (23) are provided, as well as methods of supporting the metal part (12), evacuating the chamber (14) with a vacuum subassembly (18) and heating all of the components to the desired temperature.

  15. 2005 Minerals Yearbook ZirconiuM and HafniuM

    E-Print Network [OSTI]

    2005 Minerals Yearbook ZirconiuM and HafniuM U.S. Department of the Interior U.S. Geological Survey of the mining and processing of heavy-mineral sands containing the titanium minerals ilmenite and rutile.). duPont produced zircon from its heavy-mineral sands operation near Starke, fL. iluka produced zircon

  16. ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)

    E-Print Network [OSTI]

    ). Government Stockpile: None. Events, Trends, and Issues: Domestic consumption of zirconium mineral coatings, and sandblasting. The leading consumers of zirconium and hafnium metal are the nuclear energy,610 1,720 Zirconium oxide1 1,520 1,600 2,260 3,340 2,270 Consumption, zirconium ores and concentrates

  17. ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)

    E-Print Network [OSTI]

    Stockpile: None. Events, Trends, and Issues: Domestic consumption of zirconium mineral concentrates coatings, and sandblasting. The leading consumers of zirconium and hafnium metal are the nuclear energy,830 1,910 Zirconium oxide1 1,600 2,260 3,340 2,400 3,310 Consumption, zirconium ores and concentrates

  18. Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments

    SciTech Connect (OSTI)

    MJ Trbovich; DP Barry; RE Slovacck; Y Danon; RC Block; JA Burke; NJ Drindak; G Leinweber; RV Ballad

    2004-10-13T23:59:59.000Z

    The focus of this work is to determine resonance parameters for stable hafnium isotopes in the 0.005-200 eV region, with special emphasis on the overlapping {sup 176}Hf and {sup 178}Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically-enriched liquid samples. The liquid samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. Resonance integrals were calculated along with errors for each hafnium isotope using the NJOY [1] and INTER [2] codes. The isotopic resonance integrals calculated were significantly different than previously published values; however the calculated elemental hafnium resonance integral changed very little.

  19. Development of hafnium and comparison with other pressurized water reactor control rod materials

    SciTech Connect (OSTI)

    Keller, H.W.; Hollein, D.A.; Hott, A.C.; Shallenberger, J.M.

    1982-12-01T23:59:59.000Z

    Development of a special application of hafnium for pressurized water reactor control rods is discussed. A unique feature of the design is the sealing of the hafnium material inside protective stainless steel tubing, whereas in prior applications the hafnium material was exposed directly to the reactor primary coolant. A comparison is made of the new hafnium design with silver-indium-cadmium and B/sub 4/C hybrid control rod material design applications. The advantages and disadvantages of the alternative designs are summarized, including performance and fabrication considerations.

  20. Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments

    SciTech Connect (OSTI)

    Trbovich, M J; Barry, D P; Slovacek, R E; Danon, Y; Block, R C; Francis, N C; Lubert, M; Burke, J A; Drindak, N J; Lienweber, G; Ballad, R

    2007-02-06T23:59:59.000Z

    The focus of this work is to determine the resonance parameters for stable hafnium isotopes in the 0.005 - 200 eV region, with special emphasis on the overlapping {sup 176}Hf and {sup 178}Hf resonances near 8 eV. Accurate hafnium cross sections and resonance parameters are needed in order to quantify the effects of hafnium found in zirconium, a metal commonly used in reactors. The accuracy of the cross sections and the corresponding resonance parameters used in current nuclear analysis tools are rapidly becoming the limiting factor in reducing the overall uncertainty on reactor physics calculations. Experiments measuring neutron capture and transmission are routinely performed at the Rensselaer Polytechnic Institute (RPI) LINAC using the time-of flight technique. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m, respectively. Capture experiments were performed using a sixteen section NaI multiplicity detector at a flight path length of 25 m. These experiments utilized several thicknesses of metallic and isotope-enriched liquid Hf samples. The liquid Hf samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analyses were performed using the R-matrix Bayesian code SAMMY. A combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005 - 200 eV. Additionally, resonance integrals were calculated, along with errors for each hafnium isotope, using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than previous values. The {sup 176}Hf resonance integral, based on this work, is approximately 73% higher than the ENDF/B-VI value. This is due primarily to the changes to resonance parameters in the 8 eV resonance, the neutron width presented in this work is more than twice that of the previous value. The calculated elemental hafnium resonance integral however, changed very little.

  1. Union Carbides Last 20 Years in Oak Ridge

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy Research and Development AdministrationDepartment of Energy's Oak Ridge, Paducah and Portsmouth facilities, how about the last 20 years of Union Carbide's tenure here...

  2. Modified silicon carbide whiskers

    DOE Patents [OSTI]

    Tiegs, Terry N. (Lenoir City, TN); Lindemer, Terrence B. (Oak Ridge, TN)

    1991-01-01T23:59:59.000Z

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  3. Modified silicon carbide whiskers

    DOE Patents [OSTI]

    Tiegs, T.N.; Lindemer, T.B.

    1991-05-21T23:59:59.000Z

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  4. Phase transformations in some hafnium-tantalum-titanium-zirconium alloys

    SciTech Connect (OSTI)

    Ohriner, E.K. [Oak Ridge National Lab., TN (United States); Kapoor, D. [Army ARDEC, Picatinny Arsenal, NJ (United States)

    1997-11-01T23:59:59.000Z

    Phase transformations in hafnium alloys are of interest as a means of achieving a material which exhibits flow softening and high localized strains during deformation at high strain rates. Hafnium transforms from a body-centered-cubic beta phase to a hexagonal alpha phase upon cooling below 1749{degrees}C. Hafnium-based alloys containing up to 17.5% Ti, up to 17.5% Ta, and up to 7.3% Zr by weight were button-arc melted and, in some cases, hot extruded to obtain a refined grain size. A number of alloys were shown to have beta solvus temperatures in the range of 1100 to 1300{degrees}C and showed evidence of a shear transformation upon water quenching. The Vickers microhardness of the quenched materials are typically above 350 HV as compared to 300 HV or less for materials with an alpha plus beta structure. Quenching dilatometry indicates a martensite start temperature of about 750{degrees}C for the Hf-7.5 Ta-10 Ti-1 Zr alloy and 800{degrees}C or more for the Hf-7.5 Ta-7.5 Ti-1 Zr alloy. Tensile tests at 1 s{sup {minus}1} strain rate show a constant ultimate tensile strength for temperatures up to 600{degrees}C for the above two alloys and a rapid decrease in strength with a further increase in temperature.

  5. Process for microwave sintering boron carbide

    DOE Patents [OSTI]

    Holcombe, Cressie E. (440 Sugarwood Dr., Knoxville, TN 37922); Morrow, Marvin S. (Rte. #3, Box 113, Kingston, TN 37763)

    1993-01-01T23:59:59.000Z

    A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

  6. Nanoscale Engineering Of Radiation Tolerant Silicon Carbide....

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Engineering Of Radiation Tolerant Silicon Carbide. Nanoscale Engineering Of Radiation Tolerant Silicon Carbide. Abstract: Radiation tolerance is determined by how effectively the...

  7. A look back at Union Carbides FIRST 20 Years in Nuclear Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A look back at Union Carbide's FIRST 20 Years in Nuclear Energy The Y-12 Plant Milestones Note: Union Carbide Nuclear Division, which started out as Carbide and Carbon Chemicals...

  8. A look back at Union Carbides FIRST 20 Years in Nuclear Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The Y-12 Plant Note: Union Carbide Nuclear Division, which started out as Carbide and Carbon Chemicals Company, operated the Atomic Energy CommissionEnergy Research and...

  9. Hafnium-doped tantalum oxide high-k gate dielectric films for future CMOS technology 

    E-Print Network [OSTI]

    Lu, Jiang

    2007-04-25T23:59:59.000Z

    A novel high-k gate dielectric material, i.e., hafnium-doped tantalum oxide (Hf-doped TaOx), has been studied for the application of the future generation metal-oxidesemiconductor field effect transistor (MOSFET). The ...

  10. Environmental behavior of hafnium : the impact on the disposition of weapons-grade plutonium

    E-Print Network [OSTI]

    Cerefice, Gary Steven

    1999-01-01T23:59:59.000Z

    Experimental and analytical studies were performed to examine the environmental behavior of hafnium and its utility as a neutron poison for the disposition of weapons-grade plutonium in Yucca Mountain. The hydrolysis of ...

  11. Electrical characteristics and interface structure of magnetic tunnel junctions with hafnium oxyfluoride barrier

    SciTech Connect (OSTI)

    Yu, Y.Y.; Kim, D.S.; Char, K. [Center for Strongly Correlated Materials Research and School of Physics, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2004-12-01T23:59:59.000Z

    We have studied the effects of fluorine inclusion on the electrical transport characteristics and interface structure of the hafnium oxide barrier in a magnetic tunnel junction. The tunneling magnetoresistance (TMR) and resistance-area (RA) as a function of oxidation time show that the TMR ratio of the hafnium oxyfluoride barrier is higher (8.3%) than that of the hafnium oxide barrier (5.7%) at their optimum conditions, and the oxyfluoride barrier junctions maintain a high TMR ratio even when the RA product increases by three orders of magnitude. X-ray photoelectron spectroscopy analysis shows that the fluorine atoms in the oxyfluoride barrier play an important role in the formation of a barrier with uniform composition. We believe that the initial fluoride layer is causing the subsequent oxygen diffusion to slow down, resulting in the formation of a defect-free hafnium oxide layer. These results are consistent with what we have found for aluminum oxyfluoride barriers.

  12. Growth mode evolution of hafnium oxide by atomic layer deposition

    SciTech Connect (OSTI)

    Nie, Xianglong; Ma, Fei; Ma, Dayan, E-mail: madayan@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, Shaanxi (China); Xu, Kewei [State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, People's Republic of China and Department of Physics and Opt-electronic Engineering, Xi'an University of Arts and Science, Xi'an 710065, Shaanxi (China)

    2014-01-15T23:59:59.000Z

    HfO{sub 2} thin films were deposited using tetrakis-ethylmethylamido hafnium and H{sub 2}O as precursors on silicon by atomic layer deposition (ALD). The morphology and microstructures at different ALD cycles were characterized by atomic force microscopy and high-resolution transmission electron microscopy. Based on the height–height correlation function and power spectral density function, quantitative analysis of surface morphologies was performed. Three characteristic dimensions (?{sub 1}, ?{sub 2}, and ?{sub 3}) corresponding to three surface structures, islands, local and global fluctuations, were identified. The evolution of ALD growth mode at range of the three critical scales was investigated, respectively. It suggests the transformation of growth mode from quasi two-dimensional layer-by-layer to three-dimensional island for global fluctuations.

  13. Reinvestigation of high pressure polymorphism in hafnium metal

    SciTech Connect (OSTI)

    Pandey, K. K., E-mail: kkpandey@barc.gov.in; Sharma, Surinder M. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai-400 085 (India); Gyanchandani, Jyoti; Dey, G. K. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai-400 085 (India); Somayazulu, M. [Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015 (United States); Sikka, S. K. [Indian National Science Academy, New Delhi-110 002 (India)

    2014-06-21T23:59:59.000Z

    There has been a recent controversy about the high pressure polymorphism of Hafnium (Hf). Unlike, the earlier known ??? structural transition at 38?±?8?GPa, at ambient temperature, Hrubiak et al. [J. Appl. Phys. 111, 112612 (2012)] did not observe it till 51?GPa. They observed this transition only at elevated temperatures. We have reinvestigated the room temperature phase diagram of Hf, employing x-ray diffraction (XRD) and DFT based first principles calculations. Experimental investigations have been carried out on several pure and impure Hf samples and also with different pressure transmitting media. Besides demonstrating the significant role of impurity levels on the high pressure phase diagram of Hf, our studies re-establish room temperature ??? transition at high pressures, even in quasi-hydrostatic environment. We observed this transition in pure Hf with equilibrium transition pressure P{sub o}?=?44.5?GPa; however, with large hysteresis. The structural sequence, transition pressures, the lattice parameters, the c/a ratio and its variation with compression for the ? and ? phases as predicted by our ab-initio scalar relativistic (SR) calculations are found to be in good agreement with our experimental results of pure Hf.

  14. Diamond-silicon carbide composite

    DOE Patents [OSTI]

    Qian, Jiang; Zhao, Yusheng

    2006-06-13T23:59:59.000Z

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5–8 GPa, T=1400K–2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  15. Abrasive slurry composition for machining boron carbide

    DOE Patents [OSTI]

    Duran, E.L.

    1984-11-29T23:59:59.000Z

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  16. Abrasive slurry composition for machining boron carbide

    DOE Patents [OSTI]

    Duran, Edward L. (Santa Fe, NM)

    1985-01-01T23:59:59.000Z

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  17. Method for making boron carbide cermets

    DOE Patents [OSTI]

    Cline, C.F.; Fulton, F.J.

    1987-11-03T23:59:59.000Z

    A method for synthesizing low density cermets of boron carbide and a metal binder, using decomposition of a metallic compound at controlled temperature and pressure is disclosed.

  18. U.S. GEOLOGICAL SURVEY--MINERALS INFORMATION 1 ZIRCONIUM AND HAFNIUM

    E-Print Network [OSTI]

    U.S. GEOLOGICAL SURVEY--MINERALS INFORMATION 1 ZIRCONIUM AND HAFNIUM By Joseph Gambogi Zirconium at crust; however, zircon is the primary naturally occurring mineral the Old Hickory deposit south of the mining and processing zircon (Mineral Sands Report, 1997b). of heavy-mineral sands for the titanium

  19. Synthesis and characterization of hafnium and molybdenum bifunctional initiators for the preparation of triblock copolymers

    E-Print Network [OSTI]

    Gabert, Andrea Jennifer

    2007-01-01T23:59:59.000Z

    Chapter 1. Three monofunctional mixed alkyl hafnium complexes containing the (MesNpy)2 ligand ([(MesitylNCH2)2CMe(2-CsH4N)]2) were synthesized. (MesNpy)Hf(Neo)R ((2b), R = Me; Neo = CH2CMe2Ph) and (MesNpy)Hf(CH2TMS)(R), ...

  20. Ancient recycled mantle lithosphere in the Hawaiian plume: OsmiumHafnium isotopic evidence from

    E-Print Network [OSTI]

    Reiners, Peter W.

    Ancient recycled mantle lithosphere in the Hawaiian plume: Osmium­Hafnium isotopic evidence from that recycled (i.e. previously subducted) basaltic oceanic crust (with or without sediments) is part of an ancient (N2 Ga) depleted and recycled mantle lithosphere that is part of the upwelling Hawaiian plume

  1. Nitride-bonded silicon carbide composite filter

    SciTech Connect (OSTI)

    Thomson, B.N.; DiPietro, S.G.

    1995-12-01T23:59:59.000Z

    The objective of this program is to develop and demonstrate an advanced hot gas filter, using ceramic component technology, with enhanced durability to provide increased resistance to thermal fatigue and crack propagation. The material is silicon carbide fiber reinforced nitride bonded silicon carbide.

  2. Titanium carbide bipolar plate for electrochemical devices

    DOE Patents [OSTI]

    LaConti, Anthony B. (Lynnfield, MA); Griffith, Arthur E. (Lynn, MA); Cropley, Cecelia C. (Acton, MA); Kosek, John A. (Danvers, MA)

    2000-07-04T23:59:59.000Z

    A corrosion resistant, electrically conductive, non-porous bipolar plate is made from titanium carbide for use in an eletrochemical device. The process involves blending titanium carbide powder with a suitable binder material, and molding the mixture, at an elevated temperature and pressure.

  3. Summary report on four foot septifoil cooling experiment

    SciTech Connect (OSTI)

    Randolph, H.W.; Collins, S.L.; Verebelyi, D.T.; Foti, D.J.

    1991-10-01T23:59:59.000Z

    Cooling parameters for some of the SRS reactor internal components are computed using the Transient Reactor Analysis Code, TRAC.'' In order to benchmark the code, the Safety Analysis Group of SRL requested an experiment to provide measurements of cooling parameters in a well defined physical system utilizing SRS reactor component(s). The experiment selected included a short length of septifoil with both top and bottom fittings containing five simulated control rods in an unseated'' configuration. Power level to be supplied to the rods was targeted at 2.5 kilowatts per foot. The septifoil segment was to be operated with no forced flow in order to evaluate thermal-hydraulic cooling. Parameters to be measured for comparison with code predictions were basic cooling phenomena, incidence of film boiling, thermal-hydraulic flow rate, pressure rise, and ratio of heat transfer through the wall of the assembly vs heat transfer to axial water flow through the assembly. Experimental apparatus was designed and assembled incorporating five simulated control rods four feet long, joule heated inside a five foot length of type Q'' septifoil. Water at 70 C was fed independently to the bottom inlet and along the outside of the septifoil. Water flowing along the outside of the septifoil was in confined flow and provided calorimetry to measure power flow through the septifoil housing. A shadowgraph technique was developed and used to monitor unforced flow of water pumped thermal-hydraulically through the septifoil. Electrical power of 10,000 to 70,000 watts was fed to the simulated rods from a dc power supply. Computer data acquisition was accomplished using LabView'' software programmed to match the configuration of the experiment along with scanning digital voltmeters and requisite signal sensors. Video camcorders were used to provide video records of six areas of the experiment.

  4. Summary report on four foot septifoil cooling experiment

    SciTech Connect (OSTI)

    Randolph, H.W.; Collins, S.L.; Verebelyi, D.T.; Foti, D.J.

    1991-10-01T23:59:59.000Z

    Cooling parameters for some of the SRS reactor internal components are computed using the Transient Reactor Analysis Code, ``TRAC.`` In order to benchmark the code, the Safety Analysis Group of SRL requested an experiment to provide measurements of cooling parameters in a well defined physical system utilizing SRS reactor component(s). The experiment selected included a short length of septifoil with both top and bottom fittings containing five simulated control rods in an ``unseated`` configuration. Power level to be supplied to the rods was targeted at 2.5 kilowatts per foot. The septifoil segment was to be operated with no forced flow in order to evaluate thermal-hydraulic cooling. Parameters to be measured for comparison with code predictions were basic cooling phenomena, incidence of film boiling, thermal-hydraulic flow rate, pressure rise, and ratio of heat transfer through the wall of the assembly vs heat transfer to axial water flow through the assembly. Experimental apparatus was designed and assembled incorporating five simulated control rods four feet long, joule heated inside a five foot length of type ``Q`` septifoil. Water at 70 C was fed independently to the bottom inlet and along the outside of the septifoil. Water flowing along the outside of the septifoil was in confined flow and provided calorimetry to measure power flow through the septifoil housing. A shadowgraph technique was developed and used to monitor unforced flow of water pumped thermal-hydraulically through the septifoil. Electrical power of 10,000 to 70,000 watts was fed to the simulated rods from a dc power supply. Computer data acquisition was accomplished using ``LabView`` software programmed to match the configuration of the experiment along with scanning digital voltmeters and requisite signal sensors. Video camcorders were used to provide video records of six areas of the experiment.

  5. The production of iron carbide

    SciTech Connect (OSTI)

    Anderson, K.M.; Scheel, J. [Nucor Iron Carbide, Inc., Point Lisas (Trinidad and Tobago)

    1997-12-31T23:59:59.000Z

    From start-up in 1994 to present, Nucor`s Iron Carbide plant has overcome many obstacles in achieving design production. Many of these impediments were due to flaws in equipment design. With the integration existing within the plant, limitations in any one system reduced the operating capacity of others. For this reason, as modifications were made and system capacities were increased, the need for additional modifications became apparent. Subsequently, operating practices, maintenance scheduling, employee incentives, and production objectives were continually adapted. This paper discusses equipment and design corrections and the quality issues that contributed to achieving the plant`s production capacity.

  6. Manufacture of silicon carbide using solar energy

    DOE Patents [OSTI]

    Glatzmaier, Gregory C. (Boulder, CO)

    1992-01-01T23:59:59.000Z

    A method is described for producing silicon carbide particles using solar energy. The method is efficient and avoids the need for use of electrical energy to heat the reactants. Finely divided silica and carbon are admixed and placed in a solar-heated reaction chamber for a time sufficient to cause a reaction between the ingredients to form silicon carbide of very small particle size. No grinding of silicon carbide is required to obtain small particles. The method may be carried out as a batch process or as a continuous process.

  7. Infrared spectroscopic study of atomic layer deposition mechanism for hafnium silicate thin films using HfCl2N,,SiMe3...22 and H2O

    E-Print Network [OSTI]

    George, Steven M.

    Infrared spectroscopic study of atomic layer deposition mechanism for hafnium silicate thin films was used to study the atomic layer deposition mechanism of hafnium silicate films with dichlorobis EOT.2 Among many other high-k materials, hafnium silicate is considered to be the most promising

  8. Hafnium nitride buffer layers for growth of GaN on silicon

    DOE Patents [OSTI]

    Armitage, Robert D.; Weber, Eicke R.

    2005-08-16T23:59:59.000Z

    Gallium nitride is grown by plasma-assisted molecular-beam epitaxy on (111) and (001) silicon substrates using hafnium nitride buffer layers. Wurtzite GaN epitaxial layers are obtained on both the (111) and (001) HfN/Si surfaces, with crack-free thickness up to 1.2 {character pullout}m. However, growth on the (001) surface results in nearly stress-free films, suggesting that much thicker crack-free layers could be obtained.

  9. Silver transport in CVD silicon carbide

    E-Print Network [OSTI]

    MacLean, Heather J. (Heather Jean), 1974-

    2004-01-01T23:59:59.000Z

    Ion implantation and diffusion couple experiments were used to study silver transport through and release from CVD silicon carbide. Results of these experiments show that silver does not migrate via classical diffusion in ...

  10. Electroextraction of boron from boron carbide scrap

    SciTech Connect (OSTI)

    Jain, Ashish [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Anthonysamy, S., E-mail: sas@igcar.gov.in [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Ghosh, C. [Physical Metallurgy Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Ravindran, T.R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Divakar, R.; Mohandas, E. [Physical Metallurgy Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India)

    2013-10-15T23:59:59.000Z

    Studies were carried out to extract elemental boron from boron carbide scrap. The physicochemical nature of boron obtained through this process was examined by characterizing its chemical purity, specific surface area, size distribution of particles and X-ray crystallite size. The microstructural characteristics of the extracted boron powder were analyzed by using scanning electron microscopy and transmission electron microscopy. Raman spectroscopic examination of boron powder was also carried out to determine its crystalline form. Oxygen and carbon were found to be the major impurities in boron. Boron powder of purity ? 92 wt. % could be produced by the electroextraction process developed in this study. Optimized method could be used for the recovery of enriched boron ({sup 10}B > 20 at. %) from boron carbide scrap generated during the production of boron carbide. - Highlights: • Recovery of {sup 10}B from nuclear grade boron carbide scrap • Development of process flow sheet • Physicochemical characterization of electroextracted boron • Microscopic examination of electroextracted boron.

  11. Combustion Synthesis of Silicon Carbide 389 Combustion Synthesis of Silicon Carbide

    E-Print Network [OSTI]

    Mukasyan, Alexander

    Combustion Synthesis of Silicon Carbide 389 X Combustion Synthesis of Silicon Carbide Alexander S. Mukasyan University of Notre Dame USA 1. Introduction Combustion synthesis (CS) is an effective technique by which combustion synthesis can occur: self - propagating high-temperature synthesis (SHS) and volume

  12. Carbide-derived carbons - From porous networks to nanotubes and...

    Office of Scientific and Technical Information (OSTI)

    Carbide-derived carbons - From porous networks to nanotubes and graphene Re-direct Destination: Carbide-derived carbons (CDCs) are a large family of carbon materials derived from...

  13. The diffusion bonding of silicon carbide and boron carbide using refractory metals

    SciTech Connect (OSTI)

    Cockeram, B.V.

    1999-10-01T23:59:59.000Z

    Joining is an enabling technology for the application of structural ceramics at high temperatures. Metal foil diffusion bonding is a simple process for joining silicon carbide or boron carbide by solid-state, diffusive conversion of the metal foil into carbide and silicide compounds that produce bonding. Metal diffusion bonding trials were performed using thin foils (5 {micro}m to 100 {micro}m) of refractory metals (niobium, titanium, tungsten, and molybdenum) with plates of silicon carbide (both {alpha}-SiC and {beta}-SiC) or boron carbide that were lapped flat prior to bonding. The influence of bonding temperature, bonding pressure, and foil thickness on bond quality was determined from metallographic inspection of the bonds. The microstructure and phases in the joint region of the diffusion bonds were evaluated using SEM, microprobe, and AES analysis. The use of molybdenum foil appeared to result in the highest quality bond of the metal foils evaluated for the diffusion bonding of silicon carbide and boron carbide. Bonding pressure appeared to have little influence on bond quality. The use of a thinner metal foil improved the bond quality. The microstructure of the bond region produced with either the {alpha}-SiC and {beta}-SiC polytypes were similar.

  14. Deposition method for producing silicon carbide high-temperature semiconductors

    DOE Patents [OSTI]

    Hsu, George C. (La Crescenta, CA); Rohatgi, Naresh K. (W. Corine, CA)

    1987-01-01T23:59:59.000Z

    An improved deposition method for producing silicon carbide high-temperature semiconductor material comprising placing a semiconductor substrate composed of silicon carbide in a fluidized bed silicon carbide deposition reactor, fluidizing the bed particles by hydrogen gas in a mildly bubbling mode through a gas distributor and heating the substrate at temperatures around 1200.degree.-1500.degree. C. thereby depositing a layer of silicon carbide on the semiconductor substrate.

  15. Fabrication of thorium bearing carbide fuels

    DOE Patents [OSTI]

    Gutierrez, Rueben L. (Los Alamos, NM); Herbst, Richard J. (Los Alamos, NM); Johnson, Karl W. R. (Los Alamos, NM)

    1981-01-01T23:59:59.000Z

    Thorium-uranium carbide and thorium-plutonium carbide fuel pellets have been fabricated by the carbothermic reduction process. Temperatures of 1750.degree. C. and 2000.degree. C. were used during the reduction cycle. Sintering temperatures of 1800.degree. C. and 2000.degree. C. were used to prepare fuel pellet densities of 87% and >94% of theoretical, respectively. The process allows the fabrication of kilogram quantities of fuel with good reproducibility of chemicals and phase composition. Methods employing liquid techniques that form carbide microspheres or alloying-techniques which form alloys of thorium-uranium or thorium-plutonium suffer from limitation on the quantities processed of because of criticality concerns and lack of precise control of process conditions, respectively.

  16. Carbides composite surface layers produced by (PTA)

    SciTech Connect (OSTI)

    Tajoure, Meloud, E-mail: Tajoore2000@yahoo.com [MechanicalEng.,HIHM,Gharian (Libya); Tajouri, Ali, E-mail: Tajouri-am@yahoo.com, E-mail: dr.mokhtarphd@yahoo.com; Abuzriba, Mokhtar, E-mail: Tajouri-am@yahoo.com, E-mail: dr.mokhtarphd@yahoo.com [Materials and Metallurgical Eng., UOT, Tripoli (Libya); Akreem, Mosbah, E-mail: makreem@yahoo.com [Industrial Research Centre,Tripoli (Libya)

    2013-12-16T23:59:59.000Z

    The plasma transferred arc technique was applied to deposit a composite layer of nickel base with tungsten carbide in powder form on to surface of low alloy steel 18G2A type according to polish standard. Results showed that, plasma transferred arc hard facing process was successfully conducted by using Deloro alloy 22 plus tungsten carbide powders. Maximum hardness of 1489 HV and minimum dilution of 8.4 % were achieved by using an arc current of 60 A. However, when the current was further increased to 120 A and the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base deposit with tungsten carbide features uniform distribution of reinforcement particles with regular grain shape half - dissolved in the matrix.

  17. Radiation damage in neutron irradiated boron carbide

    SciTech Connect (OSTI)

    Shcherbak, V.I.; Bykov, V.N.; Rudenko, V.A.; Tarasikov, V.P.

    1986-09-01T23:59:59.000Z

    In view of the fact that there is no information on the microstructure of specimens of boron carbide containing up to 60% B 10 isotope and irradiated at a temperature of 350-370 C, the authors undertook a detailed study of the radiation-induced defects in such material. The microstructure of unexposed boron carbide is characterized by the presence of pores originating during the technological process, dislocations, and twins. Irradiation of B/sub 4/C leads to the formation of defects measuring 3-20 nm and exhibiting a contrast that is characteristic of dislocation loops or two-dimensional second-phase precipitates and spherical pores measuring 1-4 nm in diameter. A specific microstructural feature of irradiated boron carbide is the formation of 30 nm wide zones that are free from pores and other radiation-induced defects near the gain boundaries. The obtained results indicate that irradiation of boron carbide in the 350-370 C range leads to the formation of several types of defects that can be detected by their image contrast under different conditions of photographing.

  18. High Q silicon carbide microdisk resonator

    SciTech Connect (OSTI)

    Lu, Xiyuan [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Lee, Jonathan Y. [Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627 (United States); Feng, Philip X.-L. [Department of Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Lin, Qiang, E-mail: qiang.lin@rochester.edu [Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627 (United States); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

    2014-05-05T23:59:59.000Z

    We demonstrate a silicon carbide (SiC) microdisk resonator with optical Q up to 5.12?×?10{sup 4}. The high optical quality, together with the diversity of whispering-gallery modes and the tunability of external coupling, renders SiC microdisk a promising platform for integrated quantum photonics applications.

  19. PHYSICAL REVIEW B 83, 115329 (2011) Diffusion and interface growth in hafnium oxide and silicate ultrathin films on Si(001)

    E-Print Network [OSTI]

    Garfunkel, Eric

    PHYSICAL REVIEW B 83, 115329 (2011) Diffusion and interface growth in hafnium oxide and silicate­oxide­semiconductor (CMOS) technology necessary.1,2 Transition metal (Hf, Zr, La) oxides, silicates, and ternary Hf to be desirable to have at least one monolayer of SiO2 at the dielectric/Si interface. The Hf oxide (silicate

  20. TUNGSTEN AND HAFNIUM DISTRIBUTION IN CALCIUM-ALUMINUM INCLUSIONS (CAIs) FROM ALLENDE AND EFREMOVKA. M. Humayun1

    E-Print Network [OSTI]

    Grossman, Lawrence

    TUNGSTEN AND HAFNIUM DISTRIBUTION IN CALCIUM-ALUMINUM INCLUSIONS (CAIs) FROM ALLENDE AND EFREMOVKA with, or even earlier than, metal from CAIs and chondrules [3]. Tungsten isotope compositions represent veins [5]. Tungsten mobility is cause for concern, but is not sufficient evidence against the Kleine et

  1. RSISTIVIT LECTRIQUE A BASSE TEMPRATURE DU NIOBIUM ET D'ALLIAGES NIOBIUM-HAFNIUM EN PHASE CUBIQUE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    879 RÉSISTIVITÉ ÉLECTRIQUE A BASSE TEMPÉRATURE DU NIOBIUM ET D'ALLIAGES NIOBIUM-HAFNIUM EN PHASE électrique de deux échantillons de niobium et d'échantillons d'alliages Nb-Hf en phase cubique, de expression mathématique de la résistivité des échan- tillons. Pour le niobium, cette expression est analogue

  2. ZIRCONIUM AND HAFNIUM--2003 85.1 References that include a section mark () are found in the Internet

    E-Print Network [OSTI]

    a voluntary survey of domestic operations. Of the 45 operations surveyed, 28 responded. Data by a second voluntary survey of domestic mining operations. Of the two domestic zircon producers, which have in the Internet References Cited section. ZIRCONIUM AND HAFNIUM By James B. Hedrick Domestic survey data

  3. Diamond-silicon carbide composite and method

    DOE Patents [OSTI]

    Zhao, Yusheng (Los Alamos, NM)

    2011-06-14T23:59:59.000Z

    Uniformly dense, diamond-silicon carbide composites having high hardness, high fracture toughness, and high thermal stability are prepared by consolidating a powder mixture of diamond and amorphous silicon. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPam.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness.

  4. CarbideDerived Carbons From Porous Networks to Nanotubes and...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    low-temper- ature carbon formation for nanopowders. Also, a better understanding of graphene formation during high-temperature vacuum decomposition of silicon carbide has been...

  5. Atomistic modeling of amorphous silicon carbide using a bond...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    there is partial recovery of shortrange order. Citation: Devanathan R, F Gao, and WJ Weber.2007."Atomistic modeling of amorphous silicon carbide using a bond-order...

  6. Amorphization of Silicon Carbide by Carbon Displacement. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    plays a significant role in the amorphization. Citation: Devanathan R, F Gao, and WJ Weber.2004."Amorphization of Silicon Carbide by Carbon Displacement."Applied Physics Letters...

  7. Preparation and electrocatalytic activity of tungsten carbide and titania nanocomposite

    SciTech Connect (OSTI)

    Hu, Sujuan; Shi, Binbin; Yao, Guoxing [State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, School of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)] [State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, School of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Li, Guohua, E-mail: nanozjut@zjut.edu.cn [State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, School of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)] [State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, School of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Ma, Chunan [State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, School of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)] [State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, School of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)

    2011-10-15T23:59:59.000Z

    Graphical abstract: The electrocatalytic activity of tungsten carbide and titania nanocomposite is related to the structure, crystal phase and chemical components of the nanocomposite, and is also affected by the property of electrolyte. A synergistic effect exists between tungsten carbide and titania of the composite. Highlights: {yields} Electrocatalytic activity of tungsten carbide and titania nanocomposite with core-shell structure. {yields} Activity is related to the structure, crystal phase and chemical component of the nanocomposite. {yields} The property of electrolyte affects the electrocatalytic activity. {yields} A synergistic effect exists between tungsten carbide and titania of the composite. -- Abstract: Tungsten carbide and titania nanocomposite was prepared by combining a reduced-carbonized approach with a mechanochemical approach. The samples were characterized by X-ray diffraction, transmission electron microscope under scanning mode and X-ray energy dispersion spectrum. The results show that the crystal phases of the samples are composed of anatase, rutile, nonstoichiometry titanium oxide, monotungsten carbide, bitungsten carbide and nonstoichiometry tungsten carbide, and they can be controlled by adjusting the parameters of the reduced-carbonized approach; tungsten carbide particles decorate on the surface of titania support, the diameter of tungsten carbide particle is smaller than 20 nm and that of titania is around 100 nm; the chemical components of the samples are Ti, O, W and C. The electrocatalytic activity of the samples was measured by a cyclic voltammetry with three electrodes. The results indicate that the electrocatalytic activities of the samples are related to their crystal phases and the property of electrolyte in aqueous solution. A synergistic effect between titania and tungsten carbide is reported for the first time.

  8. Nanostructured Molybdenum Carbide: Sonochemical Synthesis and Catalytic Properties

    E-Print Network [OSTI]

    Suslick, Kenneth S.

    of metal salts.5,6 Sonochemical decomposition of transition metal carbonyl compounds has also been proven to be a useful technique to generate nanophase transition metals.7,8 Recently, molybdenum and tungsten carbides; the preparation of interstitial carbides of molybdenum and tungsten with high surface areas, however, is very

  9. Molybdenum disilicide composites reinforced with zirconia and silicon carbide

    DOE Patents [OSTI]

    Petrovic, J.J.

    1995-01-17T23:59:59.000Z

    Compositions are disclosed consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

  10. Modelling precipitation of niobium carbide in austenite: multicomponent diffusion, capillarity,

    E-Print Network [OSTI]

    Cambridge, University of

    Modelling precipitation of niobium carbide in austenite: multicomponent diffusion, capillarity, and coarsening N. Fujita and H. K. D. H. Bhadeshia The growth of niobium carbide in austenite involves the diffusion of both niobium and carbon. These elements diffuse at very different rates. A model is presented

  11. Corrosion and wear resistance of tungsten carbide-cobalt and tungsten carbide-cobalt-chromium thermal spray coatings

    SciTech Connect (OSTI)

    Quets, J.; Alford, J.R.

    1999-07-01T23:59:59.000Z

    Tungsten carbide thermal spray coatings provide wear surfaces to new and overhauled components for various industries. Their wear resistance is obtained by incorporating small tungsten carbide particles into a metal matrix. This presentation will show what parameters influence their corrosion resistance in the ASTM B-117 Salt Spray Corrosion Test,

  12. Dispersion aspects of silicon carbide gelcasting

    SciTech Connect (OSTI)

    Bleier, A.

    1991-09-01T23:59:59.000Z

    The principal objective of this research was to increase the solid loading of silicon carbide (SiC) powder, in an appropriate liquid medium, to a level that is useful for gelcasting technology. A number of factors that determine the maximum concentration of silicon carbide that can be incorporated into a pourable ceramic suspension have been identified. The pH of the system is the most critical processing parameter. Its proper adjustment (pH 11 to 13) allows SiC concentrations exceeding 50%, based on volume, to be routinely achieved without the use of additional dispersing agents. The particle size of SiC was also found to affect the maximum, attainable concentration. The surface area of the powder and the presence of free carbon in the powder, though not significantly influencing the suspension properties, determine the concentration of initiator required to induce polymerization and gelation. SiC specimens have been gelcast for powders in the size range of 0.8 to 8.5 {mu}m; the powders employed contain either {approximately} 0 or 19% carbon by weight. Finally, the generation of bubbles, typically encountered by the use of ammonia to adjust pH has been circumvented by the use of tetramethylammonium hydroxide.

  13. High temperature intermetallic binders for HVOF carbides

    SciTech Connect (OSTI)

    Shaw, K.G. [Xform, Inc., Cohoes, NY (United States); Gruninger, M.F.; Jarosinski, W.J. [Praxair Specialty Powders, Indianapolis, IN (United States)

    1994-12-31T23:59:59.000Z

    Gas turbines technology has a long history of employing the desirable high temperature physical attributes of ceramic-metallic (cermet) materials. The most commonly used coatings incorporate combinations of WC-Co and Cr{sub 3}C{sub 2}-NiCr, which have also been successfully utilized in other non-turbine coating applications. Increased turbine operating temperatures and other high temperature service conditions have made apparent the attractive notion of increasing the temperature capability and corrosion resistance of these coatings. In this study the intermetallic binder NiAl has been used to replace the cobalt and NiCr constituents of conventional WC and Cr{sub 3}C{sub 2} cermet powders. The composite carbide thermal spray powders were fabricated for use in the HVOF coating process. The structure of HVOF deposited NiAl-carbide coatings are compared directly to the more familiar WC-Co and Cr{sub 3}C{sub 2}-NiCr coatings using X-ray diffraction, back-scattered electron imaging (BEI) and electron dispersive spectroscopy (EDS). Hardness variations with temperature are reported and compared between the NiAl and Co/NiCr binders.

  14. Computational Studies of Physical Properties of Boron Carbide

    SciTech Connect (OSTI)

    Lizhi Ouyang

    2011-09-30T23:59:59.000Z

    The overall goal is to provide valuable insight in to the mechanisms and processes that could lead to better engineering the widely used boron carbide which could play an important role in current plight towards greener energy. Carbon distribution in boron carbide, which has been difficult to retrieve from experimental methods, is critical to our understanding of its structure-properties relation. For modeling disorders in boron carbide, we implemented a first principles method based on supercell approach within our G(P,T) package. The supercell approach was applied to boron carbide to determine its carbon distribution. Our results reveal that carbon prefers to occupy the end sites of the 3-atom chain in boron carbide and further carbon atoms will distribute mainly on the equatorial sites with a small percentage on the 3-atom chains and the apex sites. Supercell approach was also applied to study mechanical properties of boron carbide under uniaxial load. We found that uniaxial load can lead to amorphization. Other physical properties of boron carbide were calculated using the G(P,T) package.

  15. Separation of Nuclear Fuel Surrogates from Silicon Carbide Inert Matrix

    SciTech Connect (OSTI)

    Dr. Ronald Baney

    2008-12-15T23:59:59.000Z

    The objective of this project has been to identify a process for separating transuranic species from silicon carbide (SiC). Silicon carbide has become one of the prime candidates for the matrix in inert matrix fuels, (IMF) being designed to reduce plutonium inventories and the long half-lives actinides through transmutation since complete reaction is not practical it become necessary to separate the non-transmuted materials from the silicon carbide matrix for ultimate reprocessing. This work reports a method for that required process.l

  16. Method of preparing silicon carbide particles dispersed in an electrolytic bath for composite electroplating of metals

    DOE Patents [OSTI]

    Peng, Yu-Min (Hsinchu, TW); Wang, Jih-Wen (Hsinchu, TW); Liue, Chun-Ying (Tau-Yung, TW); Yeh, Shinn-Horng (Kaohsiung, TW)

    1994-01-01T23:59:59.000Z

    A method for preparing silicon carbide particles dispersed in an electrolytic bath for composite electroplating of metals includes the steps of washing the silicon carbide particles with an organic solvent; washing the silicon carbide particles with an inorganic acid; grinding the silicon carbide particles; and heating the silicon carbide particles in a nickel-containing solution at a boiling temperature for a predetermined period of time.

  17. Investigation of crystallization processes from hafnium silicate powders prepared from an oxychloride sol-gel

    SciTech Connect (OSTI)

    McGilvery, Catriona M. [Imperial College, London; De Gendt, S [Imperial College, London; Payzant, E Andrew [ORNL; Craven, A J [Imperial College, London; MacKenzie, M [Imperial College, London; McComb, D W [Imperial College, London

    2012-01-01T23:59:59.000Z

    Hafnium oxide and silicate materials are now incorporated into working CMOS devices, however the crystallisation mechanism is still poorly understood. In particular, addition of SiO2 to HfO2 has been shown to increase the crystallisation temperature of HfO2 hence allowing it to remain amorphous under current processing conditions. Building on earlier work we here investigate bulk HfxSi1-xO2 samples to determine the effect of SiO2 on the crystallisation pathway. Techniques such as XRD, HTXRD, thermal analysis techniques and TEM are used. It is found that the addition of SiO2 has very little affect on the crystallisation path at temperatures below 900 C but at higher temperatures a second t-HfO2 phase nucleates and is stabilised due to the strain of the surrounding amorphous SiO2 material. With an increase in SiO2 content the temperature at which this nucleation and stabilisation occurs is increased. The effect of strain has implications for inhibiting the crystallisation of the high-k layer, reduction of grain boundaries and hence diffusion, reduction of formation of interface layers and the possibility of stabilising t-HfO2 rather than m-HfO2 hence increasing the dielectric of the layer.

  18. Silicon carbide mirrors for high power applications

    SciTech Connect (OSTI)

    Takacs, P.Z.

    1981-11-01T23:59:59.000Z

    The advent of synchrotron radiation (SR) sources and high energy lasers (HEL) in recent years has brought about the need for optical materials that can withstand the harsh operating conditions in such devices. SR mirrors must be ultra-high vacuum compatible, must withstand intense x-ray irradiation without surface damage, must maintain surface figure under thermal loading and must be capable of being polished to an extremely smooth surface finish. Chemical vapor deposited (CVD) silicon carbide in combination with sintered substrate material meets these requirements and offers additional benefits as well. It is an extremely hard material and offers the possibility of being cleaned and recoated many times without degradation of the surface finish, thereby prolonging the lifetime of expensive optical components. It is an extremely strong material and offers the possibility of weight reduction over conventional mirror materials.

  19. Light Ions Response of Silicon Carbide Detectors

    E-Print Network [OSTI]

    M. De Napoli; G. Raciti; E. Rapisarda; C. Sfienti

    2006-12-14T23:59:59.000Z

    Silicon carbide (SiC) Schottky diodes 21 mum thick with small surfaces and high N-dopant concentration have been used to detect alpha particles and low energy light ions. In particular 12C and 16O beams at incident energies between 5 and 18 MeV were used. The diode active-region depletion-thickness, the linearity of the response, energy resolution and signal rise-time were measured for different values of the applied reverse bias. Moreover the radiation damage on SiC diodes irradiated with 53 MeV 16O beam has been explored. The data show that SiC material is radiation harder than silicon but at least one order of magnitude less hard than epitaxial silicon diodes. An inversion in the signal was found at a fluence of 10^15 ions/cm^2.

  20. In-Pile Experiment of a New Hafnium Aluminide Composite Material to Enable Fast Neutron Testing in the Advanced Test Reactor

    SciTech Connect (OSTI)

    Donna Post Guillen; Douglas L. Porter; James R. Parry; Heng Ban

    2010-06-01T23:59:59.000Z

    A new hafnium aluminide composite material is being developed as a key component in a Boosted Fast Flux Loop (BFFL) system designed to provide fast neutron flux test capability in the Advanced Test Reactor. An absorber block comprised of hafnium aluminide (Al3Hf) particles (~23% by volume) dispersed in an aluminum matrix can absorb thermal neutrons and transfer heat from the experiment to pressurized water cooling channels. However, the thermophysical properties, such as thermal conductivity, of this material and the effect of irradiation are not known. This paper describes the design of an in-pile experiment to obtain such data to enable design and optimization of the BFFL neutron filter.

  1. Safety of light water reactor fuel with silicon carbide cladding

    E-Print Network [OSTI]

    Lee, Youho

    2013-01-01T23:59:59.000Z

    Structural aspects of the performance of light water reactor (LWR) fuel rod with triplex silicon carbide (SiC) cladding - an emerging option to replace the zirconium alloy cladding - are assessed. Its behavior under accident ...

  2. Rapid Wolff–Kishner reductions in a silicon carbide microreactor

    E-Print Network [OSTI]

    Newman, Stephen G.

    2014-01-01T23:59:59.000Z

    Wolff–Kishner reductions are performed in a novel silicon carbide microreactor. Greatly reduced reaction times and safer operation are achieved, giving high yields without requiring a large excess of hydrazine. The corrosion ...

  3. Reactor physics assessment of thick silicon carbide clad PWR fuels

    E-Print Network [OSTI]

    Bloore, David A. (David Allan)

    2013-01-01T23:59:59.000Z

    High temperature tolerance, chemical stability and low neutron affinity make silicon carbide (SiC) a potential fuel cladding material that may improve the economics and safety of light water reactors (LWRs). "Thick" SiC ...

  4. Tungsten carbide-cobalt by Three Dimensional Printing

    E-Print Network [OSTI]

    Kelley, Andrew, III

    1998-01-01T23:59:59.000Z

    Three Dimensional Printing is an additive manufacturing process for rapid prototyping ceramic and metallic parts [Sachs, et al, 1990]. Green (not sintered) tungsten carbide-cobalt parts must have a density greater than 50% ...

  5. Silicon dioxide and hafnium dioxide evaporation characteristics from a high-frequency sweep e-beam system

    SciTech Connect (OSTI)

    Chow, R. [Lawrence Livermore National Laboratory, Livermore, California 94551-0808 (United States); Tsujimoto, N. [MDC Vacuum Products Corporation, Hayward, California 94545 (United States)

    1996-09-01T23:59:59.000Z

    Reactive oxygen evaporation characteristics were determined as a function of the front-panel control parameters provided by a programmable, high-frequency sweep e-beam system. An experimental design strategy used deposition rate, beam speed, pattern, azimuthal rotation speed, and dwell time as the variables. The optimal settings for obtaining a broad thickness distribution, efficient silicon dioxide boule consumption, and minimal hafnium dioxide defect density were generated. The experimental design analysis showed the compromises involved with evaporating these oxides. {copyright} {ital 1996 Optical Society of America.}

  6. Understanding the Irradiation Behavior of Zirconium Carbide

    SciTech Connect (OSTI)

    Motta, Arthur; Sridharan, Kumar; Morgan, Dane; Szlufarska, Izabela

    2013-10-11T23:59:59.000Z

    Zirconium carbide (ZrC) is being considered for utilization in high-temperature gas-cooled reactor fuels in deep-burn TRISO fuel. Zirconium carbide possesses a cubic B1-type crystal structure with a high melting point, exceptional hardness, and good thermal and electrical conductivities. The use of ZrC as part of the TRISO fuel requires a thorough understanding of its irradiation response. However, the radiation effects on ZrC are still poorly understood. The majority of the existing research is focused on the radiation damage phenomena at higher temperatures (>450{degree}C) where many fundamental aspects of defect production and kinetics cannot be easily distinguished. Little is known about basic defect formation, clustering, and evolution of ZrC under irradiation, although some atomistic simulation and phenomenological studies have been performed. Such detailed information is needed to construct a model describing the microstructural evolution in fast-neutron irradiated materials that will be of great technological importance for the development of ZrC- based fuel. The goal of the proposed project is to gain fundamental understanding of the radiation-induced defect formation in zirconium carbide and irradiation response (ZrC) by using a combination of state-of-the-art experimental methods and atomistic modeling. This project will combine (1) in situ ion irradiation at a specialized facility at a national laboratory, (2) controlled temperature proton irradiation on bulk samples, and (3) atomistic modeling to gain a fundamental understanding of defect formation in ZrC. The proposed project will cover the irradiation temperatures from cryogenic temperature to as high as 800{degree}C, and dose ranges from 0.1 to 100 dpa. The examination of this wide range of temperatures and doses allows us to obtain an experimental data set that can be effectively used to exercise and benchmark the computer calculations of defect properties. Combining the examination of radiation-induced microstructures mapped spatially and temporally, microstructural evolution during post-irradiation annealing, and atomistic modeling of defect formation and transport energetics will provide new, critical understanding about property changes in ZrC. The behavior of materials under irradiation is determined by the balance between damage production, defect clustering, and lattice response. In order to predict those effects at high temperatures so targeted testing can be expanded and extrapolated beyond the known database, it is necessary to determine the defect energetics and mobilities as these control damage accumulation and annealing. In particular, low-temperature irradiations are invaluable for determining the regions of defect mobility. Computer simulation techniques are particularly useful for identifying basic defect properties, especially if closely coupled with a well-constructed and complete experimental database. The close coupling of calculation and experiment in this project will provide mutual benchmarking and allow us to glean a deeper understanding of the irradiation response of ZrC, which can then be applied to the prediction of its behavior in reactor conditions.

  7. Product: Tetrakis(dimethylamino)hafnium P-6280-B Date: February 2005 Copyright 2002, 2004-2005, Praxair Technology, Inc. Page 1 of 8

    E-Print Network [OSTI]

    Rubloff, Gary W.

    -2005, Praxair Technology, Inc. Page 1 of 8 All rights reserved. Revised Praxair Material Safety Data Sheet (See-6280-B) Trade Name: Praxair® TDMAH Chemical Name: Tetrakis(dimethylamino)hafnium Synonyms: Tetrakis Telephone: Emergencies: 1-800-645-4633* Company Name: Praxair, Inc. CHEMTREC: 1-800-424-9300* 39 Old

  8. area carbide-derived carbon: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    21 22 23 24 25 Next Page Last Page Topic Index 1 Carbide and Carbide-Derived Carbon Materials with Hierarchical Pore Architecture. Open Access Theses and Dissertations Summary:...

  9. Carbide process picked for Chinese polyethylene plant

    SciTech Connect (OSTI)

    Alperowicz, N.

    1993-02-10T23:59:59.000Z

    Union Carbide (Danbury, CT) is set to sign up its eighth polyethylene (PE) license in China. The company has been selected to supply its Unipol technology to Jilin Chemical Industrial Corp. (JCIC) for a 100,000-m.t./year linear low-density PE (LLDPE) plant at Jilin. The plant will form part of a $2-billion petrochemical complex, based on a 300,000-m.t./year ethylene unit awarded to a consortium made up of Samsung Engineering (Seoul) and Linde. A 10,000-m.t./year butene-1 unit will also be built. Toyo Engineering, Snamprogetti, Mitsubishi Heavy Industries, and Linde are competing for the contract to supply the LLDPE plant. The signing is expected this spring. Two contenders are vying to supply an 80,000-m.t./year phenol plant for JCIC. They are Mitsui Engineering, offering the Mitsui Petrochemical process, and Chisso, with UOP technology. Four Unipol process PE plants are under construction in China and three are in operation. At Guangzhou, Toyo Engineering is building a 100,000-m.t./year plant, due onstream in 1995, while Snamprogetti is to finish construction of two plants in the same year at Zhonguyan (120,000 m.t./year) and at Maoming (140,000 m.t./year). The Daquing Design Institute is responsible for the engineering of a 60,000-m.t./year Unipol process PE plant, expected onstream early in 1995. Existing Unipol process PE plants are located in Qilu (60,000 m.t./year LLDPE and 120,000 m.t./year HDPE) and at Taching (60,000 m.t./year HDPE).

  10. Pulsed energy synthesis and doping of silicon carbide

    DOE Patents [OSTI]

    Truher, J.B.; Kaschmitter, J.L.; Thompson, J.B.; Sigmon, T.W.

    1995-06-20T23:59:59.000Z

    A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate is disclosed, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27--730 C is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including HETEROJUNCTION-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

  11. Pulsed energy synthesis and doping of silicon carbide

    DOE Patents [OSTI]

    Truher, Joel B. (San Rafael, CA); Kaschmitter, James L. (Pleasanton, CA); Thompson, Jesse B. (Brentwood, CA); Sigmon, Thomas W. (Beaverton, OR)

    1995-01-01T23:59:59.000Z

    A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27.degree.-730.degree. C. is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including hetero-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

  12. Structure-Property Relationship in Metal Carbides and Bimetallic Alloys

    SciTech Connect (OSTI)

    Chen, Jingguan [University of Delaware] [University of Delaware

    2014-03-04T23:59:59.000Z

    The primary objective of our DOE/BES sponsored research is to use carbide and bimetallic catalysts as model systems to demonstrate the feasibility of tuning the catalytic activity, selectivity and stability. Our efforts involve three parallel approaches, with the aim at studying single crystal model surfaces and bridging the “materials gap” and “pressure gap” between fundamental surface science studies and real world catalysis. The utilization of the three parallel approaches has led to the discovery of many intriguing catalytic properties of carbide and bimetallic surfaces and catalysts. During the past funding period we have utilized these combined research approaches to explore the possibility of predicting and verifying bimetallic and carbide combinations with enhanced catalytic activity, selectivity and stability.

  13. Process for forming silicon carbide films and microcomponents

    DOE Patents [OSTI]

    Hamza, Alex V. (Livermore, CA); Balooch, Mehdi (Berkeley, CA); Moalem, Mehran (Berkeley, CA)

    1999-01-01T23:59:59.000Z

    Silicon carbide films and microcomponents are grown on silicon substrates at surface temperatures between 900 K and 1700 K via C.sub.60 precursors in a hydrogen-free environment. Selective crystalline silicon carbide growth can be achieved on patterned silicon-silicon oxide samples. Patterned SiC films are produced by making use of the high reaction probability of C.sub.60 with silicon at surface temperatures greater than 900 K and the negligible reaction probability for C.sub.60 on silicon dioxide at surface temperatures less than 1250 K.

  14. Process for forming silicon carbide films and microcomponents

    DOE Patents [OSTI]

    Hamza, A.V.; Balooch, M.; Moalem, M.

    1999-01-19T23:59:59.000Z

    Silicon carbide films and microcomponents are grown on silicon substrates at surface temperatures between 900 K and 1700 K via C{sub 60} precursors in a hydrogen-free environment. Selective crystalline silicon carbide growth can be achieved on patterned silicon-silicon oxide samples. Patterned SiC films are produced by making use of the high reaction probability of C{sub 60} with silicon at surface temperatures greater than 900 K and the negligible reaction probability for C{sub 60} on silicon dioxide at surface temperatures less than 1250 K. 5 figs.

  15. Method for forming fibrous silicon carbide insulating material

    DOE Patents [OSTI]

    Wei, G.C.

    1983-10-12T23:59:59.000Z

    A method whereby silicon carbide-bonded SiC fiber composites are prepared from carbon-bonded C fiber composites is disclosed. Carbon-bonded C fiber composite material is treated with gaseous silicon monoxide generated from the reaction of a mixture of colloidal silica and carbon black at an elevated temperature in an argon atmosphere. The carbon in the carbon bond and fiber is thus chemically converted to SiC resulting in a silicon carbide-bonded SiC fiber composite that can be used for fabricating dense, high-strength high-toughness SiC composites or as thermal insulating materials in oxidizing environments.

  16. Method for forming fibrous silicon carbide insulating material

    DOE Patents [OSTI]

    Wei, George C. (Oak Ridge, TN)

    1984-01-01T23:59:59.000Z

    A method whereby silicon carbide-bonded SiC fiber composites are prepared from carbon-bonded C fiber composites is disclosed. Carbon-bonded C fiber composite material is treated with gaseous silicon monoxide generated from the reaction of a mixture of colloidal silica and carbon black at an elevated temperature in an argon atmosphere. The carbon in the carbon bond and fiber is thus chemically converted to SiC resulting in a silicon carbide-bonded SiC fiber composite that can be used for fabricating dense, high-strength high-toughness SiC composites or as thermal insulating materials in oxidizing environments.

  17. Computational Approach to Photonic Drilling of Silicon Carbide

    SciTech Connect (OSTI)

    Samant, Anoop N [University of Tennessee, Knoxville (UTK); Daniel, Claus [ORNL; Chand, Ronald H [ORNL; Blue, Craig A [ORNL; Dahotre, Narendra B [University of Tennessee, Knoxville (UTK)

    2009-01-01T23:59:59.000Z

    The ability of lasers to carry out drilling processes in silicon carbide ceramic was investigated in this study. A JK 701 pulsed Nd:YAG laser was used for drilling through the entire depth of silicon carbide plates of different thicknesses. The laser parameters were varied in different combinations for a well controlled drilling through the entire thickness of the SiC plates. A drilling model incorporating effects of various physical phenomena such as decomposition, evaporation induced recoil pressure, and surface tension was developed. Such comprehensive model was capable of advance prediction of the energy and time required for drilling a hole through any desired depth of material.

  18. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOE Patents [OSTI]

    Koc, Rasit (Lakewood, CO); Glatzmaier, Gregory C. (Boulder, CO)

    1995-01-01T23:59:59.000Z

    A process for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  19. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOE Patents [OSTI]

    Koc, R.; Glatzmaier, G.C.

    1995-05-23T23:59:59.000Z

    A process is disclosed for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  20. Process for preparing fine grain titanium carbide powder

    DOE Patents [OSTI]

    Janney, M.A.

    1985-03-12T23:59:59.000Z

    A method for preparing finely divided titanium carbide powder in which an organotitanate is reacted with a carbon precursor polymer to provide an admixture of the titanium and the polymer at a molecular level due to a crosslinking reaction between the organotitanate and the polymer. The resulting gel is dried, pyrolyzed to drive off volatile components and provide carbon. The resulting solids are then heated at an elevated temperature to convert the titanium and carbon to high-purity titanium carbide powder in a submicron size range.

  1. Boron-carbide-aluminum and boron-carbide-reactive metal cermets. [B/sub 4/C-Al

    DOE Patents [OSTI]

    Halverson, D.C.; Pyzik, A.J.; Aksay, I.A.

    1985-05-06T23:59:59.000Z

    Hard, tough, lighweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidated step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modules of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi..sqrt..in. These composites and methods can be used to form a variety of structural elements.

  2. Nuclear breeder reactor fuel element with silicon carbide getter

    DOE Patents [OSTI]

    Christiansen, David W. (Kennewick, WA); Karnesky, Richard A. (Richland, WA)

    1987-01-01T23:59:59.000Z

    An improved cesium getter 28 is provided in a breeder reactor fuel element or pin in the form of an extended surface area, low density element formed in one embodiment as a helically wound foil 30 located with silicon carbide, and located at the upper end of the fertile material upper blanket 20.

  3. Standard specification for nuclear-Grade boron carbide pellets

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2007-01-01T23:59:59.000Z

    1.1 This specification applies to boron carbide pellets for use as a control material in nuclear reactors. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

  4. Surface Coating of Tungsten Carbide by Electric Exploding of Contact

    SciTech Connect (OSTI)

    Grigoryev, Evgeny G. [General Physics Department, Moscow Engineering Physics Institute, Kashirskoe sh. 31, Moscow, 115409 (Russian Federation)

    2011-01-17T23:59:59.000Z

    Electric exploding of a tungsten carbide--cobalt material near-by high-speed steel surface forms on it a hardening coating. The essential structure properties of the formed coatings are determined by parameters of contact exploding electrode at the pulse current amplitude from above 106 A/cm2 and duration less than 10-4 s. The metallographic investigations of coating structures were done by microscope 'Neophot-24'. They have shown that the contact electric exploding caused the transfer of tungsten carbide and cobalt on the surface of high-speed steel. The breakdown of tungsten carbide--cobalt material took place during electrical exploding. The hardening layers of tungsten carbide and pure nanocrystalline tungsten have been formed upon the surface of high-speed steel as a result of electric exploding. Crystalline grains of tungsten have an almost spherical form and their characteristic size less than 400 nanometers. Micro hardness of the coating layers and high-speed steel structures was measured.

  5. Tungsten-yttria carbide coating for conveying copper

    DOE Patents [OSTI]

    Rothman, Albert J. (Livermore, CA)

    1993-01-01T23:59:59.000Z

    A method is provided for providing a carbided-tungsten-yttria coating on the interior surface of a copper vapor laser. The surface serves as a wick for the condensation of liquid copper to return the condensate to the interior of the laser for revolatilization.

  6. Epitaxial graphene on silicon carbide: Introduction to structured graphene

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Epitaxial graphene on silicon carbide: Introduction to structured graphene Ming Ruan 1 , Yike Hu 1, France Abstract We present an introduction to the rapidly growing field of epitaxial graphene on silicon present, highly evolved state. The potential of epitaxial graphene as a new electronic material is now

  7. Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applicaitons

    SciTech Connect (OSTI)

    Z. Zak Fang, H. Y. Sohn

    2009-03-10T23:59:59.000Z

    This report contains detailed information of the research program entitled "Development of Bulk Nanocrystalline Cemented Tungsten Carbide Materials for Industrial Applications". The report include the processes that were developed for producing nanosized WC/Co composite powders, and an ultrahigh pressure rapid hot consolidation process for sintering of nanosized powders. The mechanical properties of consolidated materials using the nanosized powders are also reported.

  8. STATUS OF HIGH FLUX ISOTOPE REACTOR IRRADIATION OF SILICON CARBIDE/SILICON CARBIDE JOINTS

    SciTech Connect (OSTI)

    Katoh, Yutai [ORNL; Koyanagi, Takaaki [ORNL; Kiggans, Jim [ORNL; Cetiner, Nesrin [ORNL; McDuffee, Joel [ORNL

    2014-09-01T23:59:59.000Z

    Development of silicon carbide (SiC) joints that retain adequate structural and functional properties in the anticipated service conditions is a critical milestone toward establishment of advanced SiC composite technology for the accident-tolerant light water reactor (LWR) fuels and core structures. Neutron irradiation is among the most critical factors that define the harsh service condition of LWR fuel during the normal operation. The overarching goal of the present joining and irradiation studies is to establish technologies for joining SiC-based materials for use as the LWR fuel cladding. The purpose of this work is to fabricate SiC joint specimens, characterize those joints in an unirradiated condition, and prepare rabbit capsules for neutron irradiation study on the fabricated specimens in the High Flux Isotope Reactor (HFIR). Torsional shear test specimens of chemically vapor-deposited SiC were prepared by seven different joining methods either at Oak Ridge National Laboratory or by industrial partners. The joint test specimens were characterized for shear strength and microstructures in an unirradiated condition. Rabbit irradiation capsules were designed and fabricated for neutron irradiation of these joint specimens at an LWR-relevant temperature. These rabbit capsules, already started irradiation in HFIR, are scheduled to complete irradiation to an LWR-relevant dose level in early 2015.

  9. SILICON CARBIDE CERAMICS FOR COMPACT HEAT EXCHANGERS

    SciTech Connect (OSTI)

    DR. DENNIS NAGLE; DR. DAJIE ZHANG

    2009-03-26T23:59:59.000Z

    Silicon carbide (SiC) materials are prime candidates for high temperature heat exchangers for next generation nuclear reactors due to their refractory nature and high thermal conductivity at elevated temperatures. This research has focused on demonstrating the potential of liquid silicon infiltration (LSI) for making SiC to achieve this goal. The major advantage of this method over other ceramic processing techniques is the enhanced capability of making high dense, high purity SiC materials in complex net shapes. For successful formation of net shape SiC using LSI techniques, the carbon preform reactivity and pore structure must be controlled to allow the complete infiltration of the porous carbon structure which allows complete conversion of the carbon to SiC. We have established a procedure for achieving desirable carbon properties by using carbon precursors consisting of two readily available high purity organic materials, crystalline cellulose and phenolic resin. Phenolic resin yields a glassy carbon with low chemical reactivity and porosity while the cellulose carbon is highly reactive and porous. By adjusting the ratio of these two materials in the precursor mixtures, the properties of the carbons produced can be controlled. We have identified the most favorable carbon precursor composition to be a cellulose resin mass ratio of 6:4 for LSI formation of SiC. The optimum reaction conditions are a temperature of 1800 C, a pressure of 0.5 Torr of argon, and a time of 120 minutes. The fully dense net shape SiC material produced has a density of 2.96 g cm{sup -3} (about 92% of pure SiC) and a SiC volume fraction of over 0.82. Kinetics of the LSI SiC formation process was studied by optical microscopy and quantitative digital image analysis. This study identified six reaction stages and provided important understanding of the process. Although the thermal conductivity of pure SiC at elevated temperatures is very high, thermal conductivities of most commercial SiC materials are much lower due to phonon scattering by impurities (e.g., sintering aids located at the grain boundaries of these materials). The thermal conductivity of our SiC was determined using the laser flash method and it is 214 W/mK at 373 K and 64 W/mK at 1273 K. These values are very close to those of pure SiC and are much higher than those of SiC materials made by industrial processes. This SiC made by our LSI process meets the thermal properties required for use in high temperature heat exchanger. Cellulose and phenolic resin carbons lack the well-defined atomic structures associated with common carbon allotropes. Atomic-scale structure was studied using high resolution transmission electron microscopy (HRTEM), nitrogen gas adsorption and helium gas pycnometry. These studies revealed that cellulose carbon exhibits a very high degree of atomic disorder and angstrom-scale porosity. It has a density of only 93% of that of pure graphite, with primarily sp2 bonding character and a low concentration of graphene clusters. Phenolic resin carbon shows more structural order and substantially less angstrom-scale porosity. Its density is 98% of that of pure graphite, and Fourier transform analysis of its TEM micrographs has revealed high concentrations of sp3 diamond and sp2 graphene nano-clusters. This is the first time that diamond nano-clusters have been observed in carbons produced from phenolic resin. AC and DC electrical measurements were made to follow the thermal conversion of microcrystalline cellulose to carbon. This study identifies five regions of electrical conductivity that can be directly correlated to the chemical decomposition and microstructural evolution during carbonization. In Region I, a decrease in overall AC conductivity occurs due to the initial loss of the polar groups from cellulose molecules. In Region II, the AC conductivity starts to increase with heat treatment temperature due to the formation and growth of conducting carbon clusters. In Region III, a further increase of AC conductivity with increasing heat treatment temperature is obs

  10. Diamond-Silicon Carbide Composite And Method For Preparation Thereof

    DOE Patents [OSTI]

    Qian, Jiang (Los Alamos, NM); Zhao, Yusheng (Los Alamos, NM)

    2005-09-06T23:59:59.000Z

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5-8 GPa, T=1400K-2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.multidot.m.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  11. Carbon-rich icosahedral boron carbide designed from first principles

    SciTech Connect (OSTI)

    Jay, Antoine; Vast, Nathalie; Sjakste, Jelena; Duparc, Olivier Hardouin [Ecole Polytechnique, Laboratoire des Solides Irradiés, CEA-DSM-IRAMIS, CNRS UMR 7642, F-91120 Palaiseau (France)

    2014-07-21T23:59:59.000Z

    The carbon-rich boron-carbide (B{sub 11}C)C-C has been designed from first principles within the density functional theory. With respect to the most common boron carbide at 20% carbon concentration B{sub 4}C, the structural modification consists in removing boron atoms from the chains linking (B{sub 11}C) icosahedra. With C-C instead of C-B-C chains, the formation of vacancies is shown to be hindered, leading to enhanced mechanical strength with respect to B{sub 4}C. The phonon frequencies and elastic constants turn out to prove the stability of the carbon-rich phase, and important fingerprints for its characterization have been identified.

  12. Protective coating for alumina-silicon carbide whisker composites

    DOE Patents [OSTI]

    Tiegs, Terry N. (Lenoir City, TN)

    1989-01-01T23:59:59.000Z

    Ceramic composites formed of an alumina matrix reinforced with silicon carbide whiskers homogenously dispersed therein are provided with a protective coating for preventing fracture strength degradation of the composite by oxidation during exposure to high temperatures in oxygen-containing atmospheres. The coating prevents oxidation of the silicon carbide whiskers within the matrix by sealing off the exterior of the matrix so as to prevent oxygen transport into the interior of the matrix. The coating is formed of mullite or mullite plus silicon oxide and alumina and is formed in place by heating the composite in air to a temperature greater than 1200.degree. C. This coating is less than about 100 microns thick and adequately protects the underlying composite from fracture strength degradation due to oxidation.

  13. Microstructure and properties of IN SITU toughened silicon carbide

    SciTech Connect (OSTI)

    De Jonghe, Lutgard C.; Ritchie, Robert O.; Zhang, Xiao Feng

    2003-05-01T23:59:59.000Z

    A silicon carbide with a fracture toughness as high as 9.1 MPa.m1/2 has been developed by hot pressing b-SiC powder with aluminum, boron, and carbon additions (ABC-SiC). Central in this material development has been systematic transmission electron microscopy (TEM) and mechanical characterizations. In particular, atomic-resolution electron microscopy and nanoprobe composition quantification were combined in analyzing grain boundary structure and nanoscale structural features.

  14. Ceramic composites reinforced with modified silicon carbide whiskers

    DOE Patents [OSTI]

    Tiegs, Terry N. (Lenoir City, TN); Lindemer, Terrence B. (Oak Ridge, TN)

    1990-01-01T23:59:59.000Z

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  15. Method for removing oxide contamination from silicon carbide powders

    DOE Patents [OSTI]

    Brynestad, J.; Bamberger, C.E.

    1984-08-01T23:59:59.000Z

    The described invention is directed to a method for removing oxide contamination in the form of oxygen-containing compounds such as SiO/sub 2/ and B/sub 2/O/sub 3/ from a charge of finely divided silicon carbide. The silicon carbide charge is contacted with a stream of hydrogen fluoride mixed with an inert gas carrier such as argon at a temperature in the range of about 200/sup 0/ to 650/sup 0/C. The oxides in the charge react with the heated hydrogen fluoride to form volatile gaseous fluorides such as SiF/sub 4/ and BF/sub 3/ which pass through the charge along with unreacted hydrogen fluoride and the carrier gas. Any residual gaseous reaction products and hydrogen fluoride remaining in the charge are removed by contacting the charge with the stream of inert gas which also cools the powder to room temperature. The removal of the oxygen contamination by practicing the present method provides silicon carbide powders with desirable pressing and sintering characteristics. 1 tab.

  16. Steam Reforming on Transition-metal Carbides from Density-functional Theory

    SciTech Connect (OSTI)

    Vojvodic, Aleksandra

    2012-05-11T23:59:59.000Z

    A screening study of the steam reforming reaction on clean and oxygen covered early transition-metal carbides surfaces is performed by means of density-functional theory calculations. It is found that carbides provide a wide spectrum of reactivities, from too reactive via suitable to too inert. Several molybdenum-based systems are identified as possible steam reforming catalysts. The findings suggest that carbides provide a playground for reactivity tuning, comparable to the one for pure metals.

  17. Tunable carbon nanotube-tungsten carbide nanoparticles heterostructures by vapor deposition

    SciTech Connect (OSTI)

    Xia, Min; Guo, Hongyan; Ge, Changchun [Institute of Special Ceramics and Powder Metallurgy, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing (China); Institute of Powder Metallurgy and Advanced Ceramics, Southwest Jiaotong University, 111, 1st Section, Northern 2nd Ring Road, Chengdu (China); Yan, Qingzhi, E-mail: qzyan@ustb.edu.cn; Lang, Shaoting [Institute of Special Ceramics and Powder Metallurgy, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing (China)

    2014-05-14T23:59:59.000Z

    A simple, versatile route for the synthesis of carbon nanotube (CNT)-tungsten carbide nanoparticles heterostructures was set up via vapor deposition process. For the first time, amorphous CNTs (?-CNTs) were used to immobilized tungsten carbide nanoparticles. By adjusting the synthesis and annealing temperature, ?-CNTs/amorphous tungsten carbide, ?-CNTs/W{sub 2}C, and CNTs/W{sub 2}C/WC heterostructures were prepared. This approach provides an efficient method to attach other metal carbides and other nanoparticles to carbon nanotubes with tunable properties.

  18. Preparation of molybdenum carbides with multiple morphologies using surfactants as carbon sources

    SciTech Connect (OSTI)

    Wang, Hongfen, E-mail: wanghongfen11@163.com [Institute of Material Science and Engineering, Ocean University of China, Qingdao 266100 (China)] [Institute of Material Science and Engineering, Ocean University of China, Qingdao 266100 (China); Wang, Zhiqi [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China)] [Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China); Chen, Shougang [Institute of Material Science and Engineering, Ocean University of China, Qingdao 266100 (China)] [Institute of Material Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2012-10-15T23:59:59.000Z

    Molybdenum carbides with surfactants as carbon sources were prepared using the carbothermal reduction of the appropriate precursors (molybdenum oxides deposited on surfactant micelles) at 1023 K under hydrogen gas. The carburized products were characterized using scanning electron microscopy (SEM), X-ray diffraction and BET surface area measurements. From the SEM images, hollow microspherical and rod-like molybdenum carbides were observed. X-ray diffraction patterns showed that the annealing time of carburization had a large effect on the conversion of molybdenum oxides to molybdenum carbides. And BET surface area measurements indicated that the difference of carbon sources brought a big difference in specific surface areas of molybdenum carbides. - Graphical abstract: Molybdenum carbides having hollow microspherical and hollow rod-like morphologies that are different from the conventional monodipersed platelet-like morphologies. Highlights: Black-Right-Pointing-Pointer Molybdenum carbides were prepared using surfactants as carbon sources. Black-Right-Pointing-Pointer The kinds of surfactants affected the morphologies of molybdenum carbides. Black-Right-Pointing-Pointer The time of heat preservation at 1023 K affected the carburization process. Black-Right-Pointing-Pointer Molybdenum carbides with hollow structures had larger specific surface areas.

  19. ORDER AND DISORDER IN CARBIDES AND NITRIDES Ch. H. DE NOVION and V. MAURICE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    transition metals, rare earths and actinides react with carbon and nitrogen to form metallic carbides or nitrogen 2p atomic electron states : they may be described by a stacking of units consisting of a central and nitrides is their large composition range, for example Tico.,, to Tic,.,, for titanium mono- carbide

  20. Silicon nitride/silicon carbide composite densified materials prepared using composite powders

    DOE Patents [OSTI]

    Dunmead, S.D.; Weimer, A.W.; Carroll, D.F.; Eisman, G.A.; Cochran, G.A.; Susnitzky, D.W.; Beaman, D.R.; Nilsen, K.J.

    1997-07-01T23:59:59.000Z

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  1. Nanostructured tungsten carbide catalysts for polymer electrolyte fuel cells X. G. Yanga

    E-Print Network [OSTI]

    Nanostructured tungsten carbide catalysts for polymer electrolyte fuel cells X. G. Yanga and C. Y/air polymer electrolyte fuel cell using nanoscale tungsten carbide as the anode catalyst and carbon supported, thereby creating a fundamental technology to reduce the cost of future fuel cell engines. The tungsten

  2. Method of enhanced lithiation of doped silicon carbide via high temperature annealing in an inert atmosphere

    SciTech Connect (OSTI)

    Hersam, Mark C.; Lipson, Albert L.; Bandyopadhyay, Sudeshna; Karmel, Hunter J; Bedzyk, Michael J

    2014-05-27T23:59:59.000Z

    A method for enhancing the lithium-ion capacity of a doped silicon carbide is disclosed. The method utilizes heat treating the silicon carbide in an inert atmosphere. Also disclosed are anodes for lithium-ion batteries prepared by the method.

  3. Development of a Robust Tri-Carbide Fueled Reactor for Multimegawatt Space Power and Propulsion Applications

    SciTech Connect (OSTI)

    Samim Anghaie; Travis W. Knight; Johann Plancher; Reza Gouw

    2004-08-11T23:59:59.000Z

    An innovative reactor core design based on advanced, mixed carbide fuels was analyzed for nuclear space power applications. Solid solution, mixed carbide fuels such as (U,Zr,Nb)c and (U,Zr, Ta)C offer great promise as an advanced high temperature fuel for space power reactors.

  4. Heat transfer to a silicon carbide/water nanofluid.

    SciTech Connect (OSTI)

    Yu, W.; France , D. M.; Smith, D. S.; Singh, D.; Timofeeva, E. V.; Routbort, J. L.; Univ. of Illinois at Chicago

    2009-07-01T23:59:59.000Z

    Heat transfer experiments were performed with a water-based nanofluid containing 170-nm silicon carbide particles at a 3.7% volume concentration and having potential commercial viability. Heat transfer coefficients for the nanofluid are presented for Reynolds numbers ranging from 3300 to 13,000 and are compared to the base fluid water on the bases of constant Reynolds number, constant velocity, and constant pumping power. Results were also compared to predictions from standard liquid correlations and a recently altered nanofluid correlation. The slip mechanisms of Brownian diffusion and thermophoresis postulated in the altered correlation were investigated in a series of heating and cooling experiments.

  5. PROPERTIES OF DEFECTS AND IMPLANTS IN Mg+ IMPLANTED SILICON CARBIDE

    SciTech Connect (OSTI)

    Jiang, Weilin; Zhu, Zihua; Varga, Tamas; Bowden, Mark E.; Manandhar, Sandeep; Roosendaal, Timothy J.; Hu, Shenyang Y.; Henager, Charles H.; Kurtz, Richard J.; Wang, Yongqiang

    2013-09-25T23:59:59.000Z

    As a candidate material for fusion reactor designs, silicon carbide (SiC) under high-energy neutron irradiation undergoes atomic displacement damage and transmutation reactions that create magnesium as one of the major metallic products. The presence of Mg and lattice disorder in SiC is expected to affect structural stability and degrade thermo-mechanical properties that could limit SiC lifetime for service. We have initiated a combined experimental and computational study that uses Mg+ ion implantation and multiscale modeling to investigate the structural and chemical effects in Mg implanted SiC and explore possible property degradation mechanisms.

  6. Method of fabricating silicon carbide coatings on graphite surfaces

    DOE Patents [OSTI]

    Varacalle, Jr., Dominic J. (Idaho Falls, ID); Herman, Herbert (Port Jefferson, NY); Burchell, Timothy D. (Oak Ridge, TN)

    1994-01-01T23:59:59.000Z

    The vacuum plasma spray process produces well-bonded, dense, stress-free coatings for a variety of materials on a wide range of substrates. The process is used in many industries to provide for the excellent wear, corrosion resistance, and high temperature behavior of the fabricated coatings. In this application, silicon metal is deposited on graphite. This invention discloses the optimum processing parameters for as-sprayed coating qualities. The method also discloses the effect of thermal cycling on silicon samples in an inert helium atmosphere at about 1600.degree.C. which transforms the coating to silicon carbide.

  7. Optical and electronic properties of two dimensional graphitic silicon carbide

    E-Print Network [OSTI]

    Lin, Xiao; Lin, Shisheng; Hakro, Ayaz Ali; Cao, Te; Chen, Hongsheng; Zhang, Baile

    2012-01-01T23:59:59.000Z

    Optical and electronic properties of two dimensional few layers graphitic silicon carbide (GSiC), in particular monolayer and bilayer, are investigated by density functional theory and found different from that of graphene and silicene. Monolayer GSiC has direct bandgap while few layers exhibit indirect bandgap. The bandgap of monolayer GSiC can be tuned by an in-plane strain. Properties of bilayer GSiC are extremely sensitive to the interlayer distance. These predictions promise that monolayer GSiC could be a remarkable candidate for novel type of light-emitting diodes utilizing its unique optical properties distinct from graphene, silicene and few layers GSiC.

  8. Method of fabricating silicon carbide coatings on graphite surfaces

    DOE Patents [OSTI]

    Varacalle, D.J. Jr.; Herman, H.; Burchell, T.D.

    1994-07-26T23:59:59.000Z

    The vacuum plasma spray process produces well-bonded, dense, stress-free coatings for a variety of materials on a wide range of substrates. The process is used in many industries to provide for the excellent wear, corrosion resistance, and high temperature behavior of the fabricated coatings. In this application, silicon metal is deposited on graphite. This invention discloses the optimum processing parameters for as-sprayed coating qualities. The method also discloses the effect of thermal cycling on silicon samples in an inert helium atmosphere at about 1,600 C which transforms the coating to silicon carbide. 3 figs.

  9. Z .Surface and Coatings Technology 130 2000 164 172 Production of high-density Ni-bonded tungsten carbide

    E-Print Network [OSTI]

    Ghoniem, Nasr M.

    Z .Surface and Coatings Technology 130 2000 164 172 Production of high-density Ni-bonded tungsten spraying; Nickel; Tungsten carbide 1. Introduction 1.1. General Since the mid-1990s, the market share of cemented Z .carbides has surpassed that of high-speed steels HSS , Z .with tungsten carbide WC having 50

  10. The solar photospheric abundance of hafnium and thorium. Results from CO5BOLD 3D hydrodynamic model atmospheres

    E-Print Network [OSTI]

    Elisabetta Caffau; L. Sbordone; H. -G. Ludwig; P. Bonifacio; M. Steffen; N. T. Behara

    2008-03-25T23:59:59.000Z

    Context: The stable element hafnium (Hf) and the radioactive element thorium (Th) were recently suggested as a suitable pair for radioactive dating of stars. The applicability of this elemental pair needs to be established for stellar spectroscopy. Aims: We aim at a spectroscopic determination of the abundance of Hf and Th in the solar photosphere based on a \\cobold 3D hydrodynamical model atmosphere. We put this into a wider context by investigating 3D abundance corrections for a set of G- and F-type dwarfs. Method: High-resolution, high signal-to-noise solar spectra were compared to line synthesis calculations performed on a solar CO5BOLD model. For the other atmospheres, we compared synthetic spectra of CO5BOLD 3D and associated 1D models. Results: For Hf we find a photospheric abundance A(Hf)=0.87+-0.04, in good agreement with a previous analysis, based on 1D model atmospheres. The weak Th ii 401.9 nm line constitutes the only Th abundance indicator available in the solar spectrum. It lies in the red wing of an Ni-Fe blend exhibiting a non-negligible convective asymmetry. Accounting for the asymmetry-related additional absorption, we obtain A(Th)=0.09+-0.03, consistent with the meteoritic abundance, and about 0.1 dex lower than obtained in previous photospheric abundance determinations. Conclusions: Only for the second time, to our knowledge, has am non-negligible effect of convective line asymmetries on an abundance derivation been highlighted. Three-dimensional hydrodynamical simulations should be employed to measure Th abundances in dwarfs if similar blending is present, as in the solar case. In contrast, 3D effects on Hf abundances are small in G- to mid F-type dwarfs and sub-giants, and 1D model atmospheres can be conveniently used.

  11. Replacing precious metals with carbide catalysts for hydrogenation reactions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ruijun, Hou [Tsinghua Univ., Beijing (China). Beijing Key Lab. of Green Chemical Reaction Engineering and Technology; Columbia Univ., New York, NY (United States); Chen, Jingguang G. [Columbia Univ., New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States); Chang, Kuan [Tsinghua Univ., Beijing (China). Beijing Key Lab. of Green Chemical Reaction Engineering and Technology; Wang, Tiefeng [Tsinghua Univ., Beijing (China). Beijing Key Lab. of Green Chemical Reaction Engineering and Technology

    2015-04-01T23:59:59.000Z

    Molybdenum carbide (Mo?C and Ni/Mo?C) catalysts were compared with Pd/SiO? for the hydrogenation of several diene molecules, 1,3- butadiene, 1,3- and 1,4-cyclohexadiene (CHD). Compared to Pd/SiO?, Mo?C showed similar hydrogenation rate for 1,3-butadiene and 1,3-CHD and even higher rate for 1,4-CHD, but with significant deactivation rate for 1,3-CHD hydrogenation. However, the hydrogenation activity of Mo?C could be completely regenerated by H? treatment at 723 K for the three molecules. The Ni modified Mo?C catalysts retained similar activity for 1,3-butadiene hydrogenation with significantly enhanced selectivity for 1-butene production. The 1-butene selectivity increased with increasing Ni loading below 15%. Among the Ni modified Mo?C catalysts, 8.6%Ni/Mo?C showed the highest selectivity to 1-butene, which was even higher selectivity than that over Pd/SiO?. Compared to Pd/SiO?, both Mo?C and Ni/Mo?C showed combined advantages in hydrogenation activity and catalyst cost reduction, demonstrating the potential to use less expensive carbide catalysts to replace precious metals for hydrogenation reactions.

  12. Replacing precious metals with carbide catalysts for hydrogenation reactions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ruijun, Hou; Chen, Jingguang G.; Chang, Kuan; Wang, Tiefeng

    2015-04-01T23:59:59.000Z

    Molybdenum carbide (Mo?C and Ni/Mo?C) catalysts were compared with Pd/SiO? for the hydrogenation of several diene molecules, 1,3- butadiene, 1,3- and 1,4-cyclohexadiene (CHD). Compared to Pd/SiO?, Mo?C showed similar hydrogenation rate for 1,3-butadiene and 1,3-CHD and even higher rate for 1,4-CHD, but with significant deactivation rate for 1,3-CHD hydrogenation. However, the hydrogenation activity of Mo?C could be completely regenerated by H? treatment at 723 K for the three molecules. The Ni modified Mo?C catalysts retained similar activity for 1,3-butadiene hydrogenation with significantly enhanced selectivity for 1-butene production. The 1-butene selectivity increased with increasing Ni loading below 15%. Among the Nimore »modified Mo?C catalysts, 8.6%Ni/Mo?C showed the highest selectivity to 1-butene, which was even higher selectivity than that over Pd/SiO?. Compared to Pd/SiO?, both Mo?C and Ni/Mo?C showed combined advantages in hydrogenation activity and catalyst cost reduction, demonstrating the potential to use less expensive carbide catalysts to replace precious metals for hydrogenation reactions.« less

  13. Method of producing novel silicon carbide articles. [Patent application

    DOE Patents [OSTI]

    Milewski, J.V.

    1982-06-18T23:59:59.000Z

    A method of producing articles comprising reaction-bonded silicon carbide (SiC) and graphite (and/or carbon) is given. The process converts the graphite (and/or carbon) in situ to SiC, thus providing the capability of economically obtaining articles made up wholly or partially of SiC having any size and shape in which graphite (and/or carbon) can be found or made. When the produced articles are made of an inner graphite (and/or carbon) substrate to which SiC is reaction bonded, these articles distinguish SiC-coated graphite articles found in the prior art by the feature of a strong bond having a gradual (as opposed to a sharply defined) interface which extends over a distance of mils. A method for forming SiC whisker-reinforced ceramic matrices is also given. The whisker-reinforced articles comprise SiC whiskers which substantially retain their structural integrity.

  14. DECODING THE MESSAGE FROM METEORITIC STARDUST SILICON CARBIDE GRAINS

    SciTech Connect (OSTI)

    Lewis, Karen M.; Lugaro, Maria; Gibson, Brad K.; Pilkington, Kate, E-mail: maria.lugaro@monash.edu, E-mail: karen.michelle.lewis@gmail.com, E-mail: bkgibson@uclan.ac.uk, E-mail: kpilkington@uclan.ac.uk [Monash Centre for Astrophysics (MoCA), Monash University, Clayton VIC 3800 (Australia)

    2013-05-01T23:59:59.000Z

    Micron-sized stardust grains that originated in ancient stars are recovered from meteorites and analyzed using high-resolution mass spectrometry. The most widely studied type of stardust is silicon carbide (SiC). Thousands of these grains have been analyzed with high precision for their Si isotopic composition. Here we show that the distribution of the Si isotopic composition of the vast majority of stardust SiC grains carries the imprints of a spread in the age-metallicity distribution of their parent stars and of a power-law increase of the relative formation efficiency of SiC dust with the metallicity. This result offers a solution for the long-standing problem of silicon in stardust SiC grains, confirms the necessity of coupling chemistry and dynamics in simulations of the chemical evolution of our Galaxy, and constrains the modeling of dust condensation in stellar winds as a function of the metallicity.

  15. Epitaxial Growth and Characterization of Silicon Carbide Films

    SciTech Connect (OSTI)

    Dhanaraj,G.; Dudley, M.; Chen, Y.; Ragothamachar, B.; Wu, B.; Zhang, H.

    2006-01-01T23:59:59.000Z

    Silicon carbide (SiC) epitaxial layers have been grown in a chemical vapor deposition (CVD) system designed and fabricated in our laboratory. Silicon tetrachloride-propane as well as silane-propane were used as precursor gases. The hot zone was designed based on simulation by using numerical modeling. Growth rates up to 200 {mu}m could be achieved. A new growth-assisted hydrogen etching was developed to show the distribution of the micropipes present in the substrate. Higher growth rate was observed on off-axis (0 0 0 1) 4 H SiC compared to the on-axis (0 0 0 1) wafer and growth mechanism was explained.

  16. The world`s first commercial iron carbide plant

    SciTech Connect (OSTI)

    Prichard, L.C.; Schad, D.

    1995-12-01T23:59:59.000Z

    The paper traces the development of Nucor`s investigation of clean iron unit processes, namely, direct reduction, and the decision to build and operate the world`s first commercial iron carbide plant. They first investigated coal based processes since the US has abundant coal reserves, but found a variety of reasons for dropping the coal-based processes from further consideration. A natural gas based process was selected, but the failure to find economically priced gas supplies stopped the development of a US based venture. It was later found that Trinidad had economically priced and abundant supplies of natural gas, and the system of government, the use of English language, and geographic location were also ideal. The cost estimates required modification of the design, but the plant was begun in April, 1993. Start-up problems with the plant are also discussed. Production should commence shortly.

  17. In situ electrochemical dilatometry of carbide-derived carbons

    SciTech Connect (OSTI)

    Hantel, M M [Paul Scherrer Institut, Villigen, Switzerland; Presser, Volker [ORNL; Gogotsi, Yury [ORNL

    2011-01-01T23:59:59.000Z

    The long life durability and extraordinary stability of supercapacitors are ascribed to the common concept that the charge storage is purely based on double-layer charging. Therefore the ideal supercapacitor electrode should be free of charge induced microscopic structural changes. However, recent in-situ investigations on different carbon materials for supercapacitor electrodes have shown that the charge and discharge is accompanied by dimensional changes of the electrode up to several percent. This work studies the influence of the pore size on the expansion behavior of carbon electrodes derived from titanium carbide-derived carbons with an average pore size between 5 and 8 Using tetraethylammonium tetrafluoroborate in acetonitrile, the swelling of the electrodes was measured by in situ dilatometry. The experiments revealed an increased expansion on the negatively charged electrode for pores below 6 , which could be described with pore swelling.

  18. In-situ Electrochemical Dilatometry of Carbide-derived Carbons

    SciTech Connect (OSTI)

    Hantel, M. M.; Presser, V.; Kotz, R.; Gogotsi, Y.

    2011-01-01T23:59:59.000Z

    The long life durability and extraordinary stability of supercapacitors are ascribed to the common concept that the charge storage is purely based on double-layer charging. Therefore the ideal supercapacitor electrode should be free of charge induced microscopic structural changes. However, recent in-situ investigations on different carbon materials for supercapacitor electrodes have shown that the charge and discharge is accompanied by dimensional changes of the electrode up to several percent. This work studies the influence of the pore size on the expansion behavior of carbon electrodes derived from titanium carbide-derived carbons with an average pore size between 5 and 8 Å. Using tetraethylammonium tetrafluoroborate in acetonitrile, the swelling of the electrodes was measured by in situ dilatometry. The experiments revealed an increased expansion on the negatively charged electrode for pores below 6 Å, which could be described with pore swelling.

  19. High surface area silicon carbide-coated carbon aerogel

    DOE Patents [OSTI]

    Worsley, Marcus A; Kuntz, Joshua D; Baumann, Theodore F; Satcher, Jr, Joe H

    2014-01-14T23:59:59.000Z

    A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust. Carbon aerogels can be coated with sol-gel silica and the silica can be converted to silicone carbide, improved the thermal stability of the carbon aerogel.

  20. Synthesis of high purity sinterable silicon carbide powder

    SciTech Connect (OSTI)

    Boecker, W.D.; Mehosky, B.L.; Rogers, R.S.C.; Storm, R.S.; Venkateswaran, V. (Carborundum Co., Niagara Falls, NY (USA). Structural Ceramics Div.)

    1989-11-01T23:59:59.000Z

    High purity, submicron silicon carbide powders were produced via gas phase synthesis using a hydrogen/argon plasma. Two test facilities were constructed, a bench-scale unit and a larger pilot scale reactor. Three candidate silicon sources were evaluated:silicon tetrachloride (SiCl{sub 4}). dimethyldichlorosilane (CH{sub 3}){sub 2}(SiCl{sub 2}) and methyltrichlorosilane (CH{sub 3}SiCl{sub 3}). Product powders were evaluated on the basis of pressureless sinterability, surface area, agglomeration, particle size distribution, phase distribution and chemistry. Three commercial powders, Starck A10, Starck B10, and Carborundum submicron alpha silicon carbide, were also evaluated for comparison to the product powders. Powders were reproducibly synthesized at a rate of one pound per hour for standard run times of five hours. Product powders exhibited chemical and physical properties equal to or exceeding the commercial powders evaluated. In limited attempts to pressureless sinter the product powders, densities of 91% of theoretical were obtained with as-produced powder. Post-processing permitted densities in excess of 97% of theoretical. X-ray diffraction of the product indicates that the product powders are primarily beta poly-types, with traces of alpha present. Increased production rates to a target level of seven pounds per hour were not possible due to current transients produced by the pilot scale power supply. Extensive unsuccessful efforts to reduce or eliminate the transients are described. Low recovered product yields resulted from a failure of a product collection filter that was not discovered until the completion of the project.

  1. Advanced Measurements of Silicon Carbide Ceramic Matrix Composites

    SciTech Connect (OSTI)

    Farhad Farzbod; Stephen J. Reese; Zilong Hua; Marat Khafizov; David H. Hurley

    2012-08-01T23:59:59.000Z

    Silicon carbide (SiC) is being considered as a fuel cladding material for accident tolerant fuel under the Light Water Reactor Sustainability (LWRS) Program sponsored by the Nuclear Energy Division of the Department of Energy. Silicon carbide has many potential advantages over traditional zirconium based cladding systems. These include high melting point, low susceptibility to corrosion, and low degradation of mechanical properties under neutron irradiation. In addition, ceramic matrix composites (CMCs) made from SiC have high mechanical toughness enabling these materials to withstand thermal and mechanical shock loading. However, many of the fundamental mechanical and thermal properties of SiC CMCs depend strongly on the fabrication process. As a result, extrapolating current materials science databases for these materials to nuclear applications is not possible. The “Advanced Measurements” work package under the LWRS fuels pathway is tasked with the development of measurement techniques that can characterize fundamental thermal and mechanical properties of SiC CMCs. An emphasis is being placed on development of characterization tools that can used for examination of fresh as well as irradiated samples. The work discuss in this report can be divided into two broad categories. The first involves the development of laser ultrasonic techniques to measure the elastic and yield properties and the second involves the development of laser-based techniques to measurement thermal transport properties. Emphasis has been placed on understanding the anisotropic and heterogeneous nature of SiC CMCs in regards to thermal and mechanical properties. The material properties characterized within this work package will be used as validation of advanced materials physics models of SiC CMCs developed under the LWRS fuels pathway. In addition, it is envisioned that similar measurement techniques can be used to provide process control and quality assurance as well as measurement of in-service degradation. Examples include composite density, distribution of porosity, fiber-matrix bond character, uniformity of weave, physical damage, and joint quality at interface bonds.

  2. Reaction-Forming Method for Producing Near Net-Shape Refractory Metal Carbides

    DOE Patents [OSTI]

    Palmisiano, Marc N.; Jakubenas, Kevin J.; Baranwal, Rita

    2004-07-20T23:59:59.000Z

    A method for reaction forming refractory metal carbides. The method involves the fabrication of a glassy carbon preform by casting an organic, resin-based liquid mixture into a mold and subsequently heat treating it in two steps, which cures and pyrolizes the resin resulting in a porous carbon preform. By varying the amounts of the constituents in the organic, resin-based liquid mixture, control over the density of the carbon preform is obtained. Control of the density and microstructure of the carbon preform allows for determination of the microstructure and properties of the refractory metal carbide material produced. The glassy carbon preform is placed on a bed of refractory metal or refractory metal--silicon alloy. The pieces are heated above the melting point of the metal or alloy. The molten metal wicks inside the porous carbon preform and reacts, forming the refractory metal carbide or refractory metal carbide plus a minor secondary phase.

  3. Behavior of triplex silicon carbide fuel cladding designs tested under simulated PWR conditions

    E-Print Network [OSTI]

    Stempien, John D. (John Dennis)

    2011-01-01T23:59:59.000Z

    A silicon carbide (SiC) fuel cladding for LWRs may allow a number of advances, including: increased safety margins under transients and accident scenarios, such as loss of coolant accidents; improved resource utilization ...

  4. Response of Nanocrystalline 3C Silicon Carbide to Heavy-Ion Irradiatio...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Citation: Jiang W, H Wang, I Kim, IT Bae, G Li, P Nachimuthu, Z Zhu, Y Zhang, and WJ Weber.2009."Response of Nanocrystalline 3C Silicon Carbide to Heavy-Ion...

  5. Reactor physics considerations for implementing silicon carbide cladding into a PWR environment

    E-Print Network [OSTI]

    Dobisesky, Jacob P. (Jacob Paul), 1987-

    2011-01-01T23:59:59.000Z

    Silicon carbide (SiC) offers several advantages over zirconium (Zr)-based alloys as a potential cladding material for Pressurized Water Reactors: very slow corrosion rate, ability to withstand much higher temperature with ...

  6. Microstructural changes induced by low energy heavy ion irradiation in titanium silicon carbide

    E-Print Network [OSTI]

    Boyer, Edmond

    Microstructural changes induced by low energy heavy ion irradiation in titanium silicon carbide CNRS 6622, Parc Valrose, 06108 Nice cedex 2, France ABSTRACT Low energy ion irradiation was used

  7. An assessment of silicon carbide as a cladding material for light water reactors

    E-Print Network [OSTI]

    Carpenter, David Michael

    2011-01-01T23:59:59.000Z

    An investigation into the properties and performance of a novel silicon carbide-based fuel rod cladding under PWR conditions was conducted. The novel design is a triplex, with the inner and outermost layers consisting of ...

  8. Utility-Scale Silicon Carbide Semiconductor: Monolithic Silicon Carbide Anode Switched Thyristor for Medium Voltage Power Conversion

    SciTech Connect (OSTI)

    None

    2010-09-01T23:59:59.000Z

    ADEPT Project: GeneSiC is developing an advanced silicon-carbide (SiC)-based semiconductor called an anode-switched thyristor. This low-cost, compact SiC semiconductor conducts higher levels of electrical energy with better precision than traditional silicon semiconductors. This efficiency will enable a dramatic reduction in the size, weight, and volume of the power converters and electronic devices it's used in.GeneSiC is developing its SiC-based semiconductor for utility-scale power converters. Traditional silicon semiconductors can't process the high voltages that utility-scale power distribution requires, and they must be stacked in complicated circuits that require bulky insulation and cooling hardware. GeneSiC's semiconductors are well suited for high-power applications like large-scale renewable wind and solar energy installations.

  9. Low cost fabrication of silicon carbide based ceramics and fiber reinforced composites

    SciTech Connect (OSTI)

    Singh, M.; Levine, S.R.

    1995-07-01T23:59:59.000Z

    A low cost processing technique called reaction forming for the fabrication of near-net and complex shaped components of silicon carbide based ceramics and composites is presented. This process consists of the production of a microporous carbon preform and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture with very good control of pore volume and pore size thereby yielding materials with tailorable microstructure and composition. Mechanical properties (elastic modulus, flexural strength, and fracture toughness) of reaction-formed silicon carbide ceramics are presented. This processing approach is suitable for various kinds of reinforcements such as whiskers, particulates, fibers (tows, weaves, and filaments), and 3-D architectures. This approach has also been used to fabricate continuous silicon carbide fiber reinforced ceramic composites (CFCC`s) with silicon carbide based matrices. Strong and tough composites with tailorable matrix microstructure and composition have been obtained. Microstructure and thermomechanical properties of a silicon carbide (SCS-6) fiber reinforced reaction-formed silicon carbide matrix composites are discussed.

  10. Infrared study on room-temperature atomic layer deposition of HfO{sub 2} using tetrakis(ethylmethylamino)hafnium and remote plasma-excited oxidizing agents

    SciTech Connect (OSTI)

    Kanomata, Kensaku [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan and Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Ohba, Hisashi; Pungboon Pansila, P.; Ahmmad, Bashir; Kubota, Shigeru; Hirahara, Kazuhiro; Hirose, Fumihiko, E-mail: fhirose@yz.yamagata-u.ac.jp [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan)

    2015-01-01T23:59:59.000Z

    Room-temperature atomic layer deposition (ALD) of HfO{sub 2} was examined using tetrakis (ethylmethylamino)hafnium (TEMAH) and remote plasma-excited water and oxygen. A growth rate of 0.26?nm/cycle at room temperature was achieved, and the TEMAH adsorption and its oxidization on HfO{sub 2} were investigated by multiple internal reflection infrared absorption spectroscopy. It was observed that saturated adsorption of TEMAH occurs at exposures of ?1?×?10{sup 5}?L (1 L?=?1?×?10{sup ?6} Torr s) at room temperature, and the use of remote plasma-excited water and oxygen vapor is effective in oxidizing the TEMAH molecules on the HfO{sub 2} surface, to produce OH sites. The infrared study suggested that Hf–OH plays a role as an adsorption site for TEMAH. The reaction mechanism of room temperature HfO{sub 2} ALD is discussed in this paper.

  11. Characterization and refinement of carbide coating formation rates and dissolution kinetics in the Ta-C system

    SciTech Connect (OSTI)

    Rodriguez, P.J.

    1996-10-01T23:59:59.000Z

    The interaction between carbide coating formation rates and dissolution kinetics in the tantalum-carbon system was investigated. The research was driven by the need to characterize carbide coating formation rates. The characterization of the carbide coating formation rates was required to engineer an optimum processing scheme for the fabrication of the ultracorrosion-resistant composite, carbon-saturated tantalum. A packed-bed carburization process was successfully engineered and employed. The packed-bed carburization process produced consistent, predictable, and repeatable carbide coatings. A digital imaging analysis measurement process for accurate and consistent measurement of carbide coating thicknesses was developed. A process for removing the chemically stable and extremely hard tantalum-carbide coatings was also developed in this work.

  12. Frontispiece: origin of extraordinary stability of square-planar carbon atoms in surface carbides of cobalt and nickel.

    E-Print Network [OSTI]

    Nandula, A; Trinh, QT; Saeys, M; Alexandrova, AN

    2015-01-01T23:59:59.000Z

    Carbides of Cobalt and Nickel** Anjan Nandula, Quang Thangcarbides of cobalt and nickel are exception- ally stable,C binds to cobalt and nickel with a remarkable affinity,

  13. Origin of Extraordinary Stability of Square-Planar Carbon Atoms in Surface Carbides of Cobalt and Nickel.

    E-Print Network [OSTI]

    Nandula, A; Trinh, QT; Saeys, M; Alexandrova, AN

    2015-01-01T23:59:59.000Z

    Carbides of Cobalt and Nickel** Anjan Nandula, Quang Thangcarbides of cobalt and nickel are exception- ally stable,C binds to cobalt and nickel with a remarkable affinity,

  14. Spectroscopic constants and potential energy curves of tungsten carbide

    SciTech Connect (OSTI)

    Balasubramanian, K. [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604 (United States)] [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604 (United States)

    2000-05-01T23:59:59.000Z

    Spectroscopic constants (R{sub e},{omega}{sub e},T{sub e},{mu}{sub e}) and potential energy curves for 40 low-lying electronic states of the diatomic tungsten carbide (WC) were obtained using the complete active space multiconfiguration self-consistent field followed by the multireference singles+doubles configuration interaction and full first- and second-order configuration interaction calculations that included up to 6.4 mil configurations. Spin-orbit effects were included through the enhanced relativistic configuration interaction method described here for 28 electronic states of WC lying below {approx}20 000 cm-1. The spin-orbit splitting of the ground state of WC was found to be very large (4394 cm-1). The ground and excited electronic states of the W atom were also computed and were found to be in good agreement with the experimental data. The nature of bonding was analyzed through the composition of orbitals, leading configurations, Mulliken populations, and dipole moments. The dissociation energy of WC was computed including spin-orbit and electron correlation effects. The recent photoelectron spectra of WC{sup -} were assigned on the basis of our computed results. (c) 2000 American Institute of Physics.

  15. Evaluation of CVD silicon carbide for synchrotron radiation mirrors

    SciTech Connect (OSTI)

    Takacs, P.Z.

    1981-07-01T23:59:59.000Z

    Chemical vapor deposited silicon carbide (CVD SiC) is a recent addition to the list of materials suitable for use in the harsh environment of synchrotron radiation (SR) beam lines. SR mirrors for use at normal incidence must be ultrahigh vacuum compatible, must withstand intense x-ray irradiation without surface damage, must be capable of being polished to an extremely smooth surface finish, and must maintain surface figure under thermal loading. CVD SiC exceeds the performance of conventional optical materials in all these areas. It is, however, a relatively new optical material. Few manufacturers have experience in producing optical quality material, and few opticians have experience in figuring and polishing the material. The CVD material occurs in a variety of forms, sensitively dependent upon reaction chamber production conditions. We are evaluating samples of CVD SiC obtained commercially from various manufacturers, representing a range of deposition conditions, to determine which types of CVD material are most suitable for superpolishing. At the time of this writing, samples are being polished by several commercial vendors and surface finish characteristics are being evaluated by various analytical methods.

  16. USE OF SILICON CARBIDE MONITORS IN ATR IRRADIATION TESTING

    SciTech Connect (OSTI)

    K. L. Davis; B. Chase; T. Unruh; D. Knudson; J. L. Rempe

    2012-07-01T23:59:59.000Z

    In April 2007, the Department of Energy (DOE) designated the Advanced Test Reactor (ATR) a National Scientific User Facility (NSUF) to advance US leadership in nuclear science and technology. By attracting new users from universities, laboratories, and industry, the ATR will support basic and applied nuclear research and development and help address the nation's energy security needs. In support of this new program, the Idaho National Laboratory (INL) has developed in-house capabilities to fabricate, test, and qualify new and enhanced temperature sensors for irradiation testing. Although most efforts emphasize sensors capable of providing real-time data, selected tasks have been completed to enhance sensors provided in irradiation locations where instrumentation leads cannot be included, such as drop-in capsule and Hydraulic Shuttle Irradiation System (HSIS) or 'rabbit' locations. For example, silicon carbide (SiC) monitors are now available to detect peak irradiation temperatures between 200°C and 800°C. Using a resistance measurement approach, specialized equipment installed at INL's High Temperature Test Laboratory (HTTL) and specialized procedures were developed to ensure that accurate peak irradiation temperature measurements are inferred from SiC monitors irradiated at the ATR. Comparison examinations were completed by INL to demonstrate this capability, and several programs currently rely on SiC monitors for peak temperature detection. This paper discusses the use of SiC monitors at the ATR, the process used to evaluate them at the HTTL, and presents representative measurements taken using SiC monitors.

  17. Synthesis, thermal stability, and photocatalytic activity of nanocrystalline titanium carbide

    SciTech Connect (OSTI)

    Chen, Youjian; Zhang, Hong [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China)] [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ma, DeKun [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China) [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Nanomaterials and Chemistry Key Laboratory, Advanced Materials Research Center of Wenzhou, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ma, Jianhua, E-mail: mjh820@ustc.edu [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China) [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Nanomaterials and Chemistry Key Laboratory, Advanced Materials Research Center of Wenzhou, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ye, Hongnan; Qian, Gaojin; Ye, Yi [Oujiang College, Wenzhou University, Wenzhou, Zhejiang 325027 (China)] [Oujiang College, Wenzhou University, Wenzhou, Zhejiang 325027 (China)

    2011-11-15T23:59:59.000Z

    Highlights: {yields} The synthesized temperature is lower than some conventional methods. {yields} These raw materials are safe; all manipulations are rather safe and convenient. {yields} The product exhibits photocatalytic activity in degradation of Rhodamine-B. -- Abstract: Titanium carbide (TiC) was prepared via one simple route by the reaction of metallic magnesium powders with titanium dioxide (TiO{sub 2}) and potassium acetate (CH{sub 3}COOK) in an autoclave at 600 {sup o}C and 8 h. Phase structure and morphology were characterized by X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). The results indicated that the product was cubic TiC, which consisted of particles with an average size of about 100 nm in diameter. The product was also studied by the thermogravimetric analysis (TGA) and its photocatalysis. It had good thermal stability and oxidation resistance below 350 {sup o}C in air. In addition, we discovered that the cubic TiC powders exhibited photocatalytic activity in degradation of Rhodamine-B (RhB) under 500 W mercury lamp light irradiation.

  18. Developing a High Thermal Conductivity Fuel with Silicon Carbide Additives

    SciTech Connect (OSTI)

    baney, Ronald; Tulenko, James

    2012-11-20T23:59:59.000Z

    The objective of this research is to increase the thermal conductivity of uranium oxide (UO{sub 2}) without significantly impacting its neutronic properties. The concept is to incorporate another high thermal conductivity material, silicon carbide (SiC), in the form of whiskers or from nanoparticles of SiC and a SiC polymeric precursor into UO{sub 2}. This is expected to form a percolation pathway lattice for conductive heat transfer out of the fuel pellet. The thermal conductivity of SiC would control the overall fuel pellet thermal conductivity. The challenge is to show the effectiveness of a low temperature sintering process, because of a UO{sub 2}-SiC reaction at 1,377°C, a temperature far below the normal sintering temperature. Researchers will study three strategies to overcome the processing difficulties associated with pore clogging and the chemical reaction of SiC and UO{sub 2} at temperatures above 1,300°C:

  19. Thermal evolution behavior of carbides and {gamma} Prime precipitates in FGH96 superalloy powder

    SciTech Connect (OSTI)

    Zhang Lin, E-mail: zhanglincsu@163.com [State Key Laboratory for Advanced Metals and Materials, Beijing Key Laboratory for Powder Metallurgy and Particulate Materials, University of Science and Technology Beijing, Beijing, 100083 (China); Liu Hengsan, E-mail: lhsj63@sohu.com [State Key Laboratory for Advanced Metals and Materials, Beijing Key Laboratory for Powder Metallurgy and Particulate Materials, University of Science and Technology Beijing, Beijing, 100083 (China); He Xinbo, E-mail: xb_he@163.com [State Key Laboratory for Advanced Metals and Materials, Beijing Key Laboratory for Powder Metallurgy and Particulate Materials, University of Science and Technology Beijing, Beijing, 100083 (China); Rafi-ud-din, E-mail: rafiuddi@gmail.com [State Key Laboratory for Advanced Metals and Materials, Beijing Key Laboratory for Powder Metallurgy and Particulate Materials, University of Science and Technology Beijing, Beijing, 100083 (China); Qu Xuanhui, E-mail: quxh@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, Beijing Key Laboratory for Powder Metallurgy and Particulate Materials, University of Science and Technology Beijing, Beijing, 100083 (China); Qin Mingli, E-mail: mlqin75@hotmail.com [State Key Laboratory for Advanced Metals and Materials, Beijing Key Laboratory for Powder Metallurgy and Particulate Materials, University of Science and Technology Beijing, Beijing, 100083 (China); Li Zhou, E-mail: zhouli621@126.com [National Key Lab of High Temperature Structural Materials, Beijing Institute of Aeronautical Materials, Beijing, 100095 (China); Zhang Guoqing, E-mail: g.zhang@126.com [National Key Lab of High Temperature Structural Materials, Beijing Institute of Aeronautical Materials, Beijing, 100095 (China)

    2012-05-15T23:59:59.000Z

    The characteristics of rapidly solidified FGH96 superalloy powder and the thermal evolution behavior of carbides and {gamma} Prime precipitates within powder particles were investigated. It was observed that the reduction of powder size and the increase of cooling rate had transformed the solidification morphologies of atomized powder from dendrite in major to cellular structure. The secondary dendritic spacing was measured to be 1.02-2.55 {mu}m and the corresponding cooling rates were estimated to be in the range of 1.4 Multiplication-Sign 10{sup 4}-4.7 Multiplication-Sign 10{sup 5} K{center_dot}s{sup -1}. An increase in the annealing temperature had rendered the phase transformation of carbides evolving from non-equilibrium MC Prime carbides to intermediate transition stage of M{sub 23}C{sub 6} carbides, and finally to thermodynamically stable MC carbides. The superfine {gamma} Prime precipitates were formed at the dendritic boundaries of rapidly solidified superalloy powder. The coalescence, growth, and homogenization of {gamma}' precipitates occurred with increasing annealing temperature. With decreasing cooling rate from 650 Degree-Sign C{center_dot}K{sup -1} to 5 Degree-Sign C{center_dot}K{sup -1}, the morphological development of {gamma} Prime precipitates had been shown to proceed from spheroidal to cuboidal and finally to solid state dendrites. Meanwhile, a shift had been observed from dendritic morphology to recrystallized structure between 900 Degree-Sign C and 1050 Degree-Sign C. Moreover, accelerated evolution of carbides and {gamma}' precipitates had been facilitated by the formation of new grain boundaries which provide fast diffusion path for atomic elements. - Highlights: Black-Right-Pointing-Pointer Microstructural characteristic of FGH96 superalloy powder was investigated. Black-Right-Pointing-Pointer The relation between microstructure, particle size, and cooling rate was studied. Black-Right-Pointing-Pointer Thermal evolution behavior of {gamma} Prime and carbides in loose FGH96 powder was studied.

  20. Inherent safety advantages of carbide fuel systems and technical issues regarding natural convection in LMRs

    SciTech Connect (OSTI)

    Barthold, W.P. [Barthold and Associates, Inc., Albuquerque, NM (United States)

    1984-08-01T23:59:59.000Z

    The scope of work is to summarize inherent safety advantages that are unique to the use of a carbide based fuel system and to summarize the technical issues regarding natural convection flow in LMFBR cores. As discussed in this report, carbide fuel provides the designer with far greater flexibility than oxide fuel. Carbide fuel systems can be designed to eliminate major accident initiators. They turn quantitative advantages into a qualitative advantage. The author proposed to LANL a series of core design and component concepts that would greatly enhance the safety of carbide over oxide systems. This report cites a series of safety advantages which potentially exist for a carbide fuel system. Natural convection issues have not been given much attention in the past. Only during the last few years has this issue been addressed in some detail. Despite claims to the contrary by some of the LMR contractors, the author does not think that the natural convection phenomena is fully understood. Some of the approximations made in natural convection transient analyses have probably a greater impact on calculated transient temperatures than the effects under investigation. Only integral in-pile experimental data and single assembly out-of-pile detailed data are available for comparisons with analytical models and correlations. Especially for derated cores, the natural convection capability of a LMR should be far superior to that of a LWR. The author ranks the natural convection capability of the LMR as the most important inherent safety feature.

  1. Threshold irradiation dose for amorphization of silicon carbide

    SciTech Connect (OSTI)

    Snead, L.L.; Zinkle, S.J.

    1997-03-01T23:59:59.000Z

    The amorphization of silicon carbide due to ion and electron irradiation is reviewed with emphasis on the temperature-dependent critical dose for amorphization. The effect of ion mass and energy on the threshold dose for amorphization is summarized, showing only a weak dependence near room temperature. Results are presented for 0.56 MeV silicon ions implanted into single crystal 6H-SiC as a function of temperature and ion dose. From this, the critical dose for amorphization is found as a function of temperature at depths well separated from the implanted ion region. Results are compared with published data generated using electrons and xenon ions as the irradiating species. High resolution TEM analysis is presented for the Si ion series showing the evolution of elongated amorphous islands oriented such that their major axis is parallel to the free surface. This suggests that surface or strain effects may be influencing the apparent amorphization threshold. Finally, a model for the temperature threshold for amorphization is described using the Si ion irradiation flux and the fitted interstitial migration energy which was found to be {approximately}0.56eV. This model successfully explains the difference in the temperature dependent amorphization behavior of SiC irradiated with 0.56 MeV Si{sup +} at 1 x 10{sup -3} dpa/s and with fission neutrons irradiated at 1 x 10{sup -6} dpa/s irradiated to 15 dpa in the temperature range of {approximately}340{+-}10K.

  2. Above: Power deposition in the superconducting magnets and the tungsten-carbide + water shield inside them, according to a

    E-Print Network [OSTI]

    McDonald, Kirk

    Above: Power deposition in the superconducting magnets and the tungsten-carbide + water shield FOR A MUON COLLIDER (TUP265, PAC11) The concept for a muon-production system for a muon collider (or neutrino Magnet shield WC beads + water Shield must dissipate 2.4 MW Superconducting magnets tungsten-carbide (WC

  3. Effect of Heat Treatment on Silicon Carbide Based Joining Materials for Fusion Energy

    SciTech Connect (OSTI)

    Lewinsohn, Charles A.; Jones, Russell H.; Nozawa, T.; Kotani, M.; Kishimoto, H.; Katoh, Y.; Kohyama, A.

    2001-10-01T23:59:59.000Z

    Two general approaches to obtaining silicon carbide-based joint materials were used. The first method relies on reactions between silicon and carbon to form silicon carbide, or to bond silicon carbide powders together. The second method consists of pyrolysing a polycarbosilane polymer to yield an amorphous, covalently bonded material. In order to assess the long-term durability of the joint materials, various heat treatments were performed and the effects on the mechanical properties of the joints were measured. Although the joints derived from the polycarbosilane polymer were not the strongest, the value of strength measured was not affected by heat treatment. On the other hand, the value of the strength of the reaction-based joints was affected by heat treatment, indicating the presence of residual stresses or unreacted material subsequent to processing. Further investigation of reaction-based joining should consist of detailed microscopic studies; however, continued study of joints derived from polymers is also warranted.

  4. Composite materials and bodies including silicon carbide and titanium diboride and methods of forming same

    DOE Patents [OSTI]

    Lillo, Thomas M.; Chu, Henry S.; Harrison, William M.; Bailey, Derek

    2013-01-22T23:59:59.000Z

    Methods of forming composite materials include coating particles of titanium dioxide with a substance including boron (e.g., boron carbide) and a substance including carbon, and reacting the titanium dioxide with the substance including boron and the substance including carbon to form titanium diboride. The methods may be used to form ceramic composite bodies and materials, such as, for example, a ceramic composite body or material including silicon carbide and titanium diboride. Such bodies and materials may be used as armor bodies and armor materials. Such methods may include forming a green body and sintering the green body to a desirable final density. Green bodies formed in accordance with such methods may include particles comprising titanium dioxide and a coating at least partially covering exterior surfaces thereof, the coating comprising a substance including boron (e.g., boron carbide) and a substance including carbon.

  5. Steam reforming on transition-metal carbides from density-functional theory

    E-Print Network [OSTI]

    Vojvodic, Aleksandra

    2009-01-01T23:59:59.000Z

    A screening study of the steam reforming reaction (CH_4 + H_2O -> CO + 3H_2) on early transition-metal carbides (TMC's) is performed by means of density-functional theory calculations. The set of considered surfaces includes the alpha-Mo_2C(100) surfaces, the low-index (111) and (100) surfaces of TiC, VC, and delta-MoC, and the oxygenated alpha-Mo_2C(100) and TMC(111) surfaces. It is found that carbides provide a wide spectrum of reactivities towards the steam reforming reaction, from too reactive via suitable to too inert. The reactivity is discussed in terms of the electronic structure of the clean surfaces. Two surfaces, the delta-MoC(100) and the oxygen passivated alpha-Mo_2C(100) surfaces, are identified as promising steam reforming catalysts. These findings suggest that carbides provide a playground for reactivity tuning, comparable to the one for pure metals.

  6. Nucor`s start up of the world`s first commercial iron carbide plant

    SciTech Connect (OSTI)

    Garraway, R. [Nucor Iron Carbide Inc., Point Lisas (Trinidad and Tobago)

    1996-12-31T23:59:59.000Z

    Nucor began startup of its 900 Tonnes/day Fe{sub 3}C plant in July 1994 and the process has produced a high quality iron carbide. The major process variables and their importance to achieving design capacity are discussed, along with results of tests using the carbide to supplement scrap metal at Nucor Steel Mills. With the potential to burn the Carbon in the Fe{sub 3}C to CO and CO{sub 2}, the conversion of pure Fe{sub 3}C to 1 Tonne of steel will require: 55% of what is required using 100% scrap and 40% of what is required using 100% DRI.

  7. Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report

    SciTech Connect (OSTI)

    Sundberg, G.J.; Vartabedian, A.M.; Wade, J.A.; White, C.S. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.

    1994-10-01T23:59:59.000Z

    The purpose of joining, Phase 2 was to develop joining technologies for HIP`ed Si{sub 3}N{sub 4} with 4wt% Y{sub 2}O{sub 3} (NCX-5101) and for a siliconized SiC (NT230) for various geometries including: butt joins, curved joins and shaft to disk joins. In addition, more extensive mechanical characterization of silicon nitride joins to enhance the predictive capabilities of the analytical/numerical models for structural components in advanced heat engines was provided. Mechanical evaluation were performed by: flexure strength at 22 C and 1,370 C, stress rupture at 1,370 C, high temperature creep, 22 C tensile testing and spin tests. While the silicon nitride joins were produced with sufficient integrity for many applications, the lower join strength would limit its use in the more severe structural applications. Thus, the silicon carbide join quality was deemed unsatisfactory to advance to more complex, curved geometries. The silicon carbide joining methods covered within this contract, although not entirely successful, have emphasized the need to focus future efforts upon ways to obtain a homogeneous, well sintered parent/join interface prior to siliconization. In conclusion, the improved definition of the silicon carbide joining problem obtained by efforts during this contract have provided avenues for future work that could successfully obtain heat engine quality joins.

  8. The origin of 2.7 eV luminescence and 5.2 eV excitation band in hafnium oxide

    SciTech Connect (OSTI)

    Perevalov, T. V., E-mail: timson@isp.nsc.ru [A. V. Rzhanov Institute of Semiconductor Physics of SB RAS, 13 Lavrentieva Ave, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk (Russian Federation); Aliev, V. Sh.; Gritsenko, V. A. [A. V. Rzhanov Institute of Semiconductor Physics of SB RAS, 13 Lavrentieva Ave, 630090 Novosibirsk (Russian Federation); Saraev, A. A. [Boreskov Institute of Catalysis of SB RAS, 5 Lavrentieva Ave, 630090 Novosibirsk (Russian Federation); Kaichev, V. V. [Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk (Russian Federation); Boreskov Institute of Catalysis of SB RAS, 5 Lavrentieva Ave, 630090 Novosibirsk (Russian Federation); Ivanova, E. V.; Zamoryanskaya, M. V. [Ioffe Physicotechnical Institute of RAS, 26 Politechnicheskaya St., 194021 St. Petersburg (Russian Federation)

    2014-02-17T23:59:59.000Z

    The origin of a blue luminescence band at 2.7 eV and a luminescence excitation band at 5.2 eV of hafnia has been studied in stoichiometric and non-stoichiometric hafnium oxide films. Experimental and calculated results from the first principles valence band spectra showed that the stoichiometry violation leads to the formation of the peak density of states in the band gap caused by oxygen vacancies. Cathodoluminescence in the non-stoichiometric film exhibits a band at 2.65 eV that is excited at the energy of 5.2 eV. The optical absorption spectrum calculated for the cubic phase of HfO{sub 2} with oxygen vacancies shows a peak at 5.3?eV. Thus, it could be concluded that the blue luminescence band at 2.7?eV and HfO{sub x} excitation peak at 5.2?eV are due to oxygen vacancies. The thermal trap energy in hafnia was estimated.

  9. Benefits of Silicon Carbide Schottky Diodes in Boost APFC Operating in CCM

    E-Print Network [OSTI]

    Benefits of Silicon Carbide Schottky Diodes in Boost APFC Operating in CCM Sam Ben solution to Boost APFC stage operating under CCM conditions. I. Introduction Boost derived Active Power true when the APFC stage operates in the Continuous Current Mode (CCM) in which the diode current does

  10. Standard specification for nuclear-grade aluminum oxide-boron carbide composite pellets

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2005-01-01T23:59:59.000Z

    1.1 This specification applies to pellets composed of mixtures of aluminum oxide and boron carbide that may be ultimately used in a reactor core, for example, in neutron absorber rods. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

  11. Towards new binary compounds: Synthesis of amorphous phosphorus carbide by pulsed laser deposition

    SciTech Connect (OSTI)

    Hart, Judy N., E-mail: Judy.Hart@bristol.ac.uk [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); May, Paul W.; Allan, Neil L. [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)] [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Hallam, Keith R. [Interface Analysis Centre, University of Bristol, 121 St. Michaels Hill, Bristol BS2 8BS (United Kingdom)] [Interface Analysis Centre, University of Bristol, 121 St. Michaels Hill, Bristol BS2 8BS (United Kingdom); Claeyssens, Frederik [Kroto Research Institute, Department of Materials Science and Engineering, University of Sheffield, Broad Lane, Sheffield S3 7HQ (United Kingdom)] [Kroto Research Institute, Department of Materials Science and Engineering, University of Sheffield, Broad Lane, Sheffield S3 7HQ (United Kingdom); Fuge, Gareth M.; Ruda, Michelle [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)] [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Heard, Peter J. [Interface Analysis Centre, University of Bristol, 121 St. Michaels Hill, Bristol BS2 8BS (United Kingdom)] [Interface Analysis Centre, University of Bristol, 121 St. Michaels Hill, Bristol BS2 8BS (United Kingdom)

    2013-02-15T23:59:59.000Z

    We have recently undertaken comprehensive computational studies predicting possible crystal structures of the as yet unknown phosphorus carbide as a function of composition. In this work, we report the synthesis of amorphous phosphorus-carbon films by pulsed laser deposition. The local bonding environments of carbon and phosphorus in the synthesised materials have been analysed by x-ray photoelectron spectroscopy; we have found strong evidence for the formation of direct P-C bonding and hence phosphorus carbide. There is a good agreement between the bonding environments found in this phosphorus carbide material and those predicted in the computational work. In particular, the local bonding environments are consistent with those found in the {beta}-InS-like structures that we predict to be low in energy for phosphorus:carbon ratios between 0.25 and 1. Highlights: Black-Right-Pointing-Pointer We have synthesised amorphous phosphorus-carbon films by pulsed laser deposition. Black-Right-Pointing-Pointer X-ray photoelectron spectroscopy results indicate formation of direct P-C bonds and hence phosphorus carbide. Black-Right-Pointing-Pointer Local bonding environments are consistent with those in predicted structures.

  12. Catalytically Assisted Self-Propagating High-Temperature Synthesis of Tantalum Carbide Powders

    E-Print Network [OSTI]

    Wooldridge, Margaret S.

    Catalytically Assisted Self-Propagating High-Temperature Synthesis of Tantalum Carbide Powders Troy high-temperature combustion synthesis (SHS) of materials has gained recognition for its energy in the context of gas-phase and solid-phase transport models. I. Introduction IN RECENT years, self-propagating

  13. Synthesis, structure, and superconducting properties of tantalum carbide nanorods and nanoparticles

    E-Print Network [OSTI]

    McHenry, Michael E.

    Synthesis, structure, and superconducting properties of tantalum carbide nanorods and nanoparticles, and HRSEM. Superconducting properties were characterized using a SQUID magnetometer. For reactions at lower in the rock salt structure and has a superconducting transition temperature of 9.7 K. In TaC nanorods

  14. Carbide-derived carbons - From porous networks to nanotubes and graphene

    SciTech Connect (OSTI)

    Presser, V.; Heon, M.; Gogotsi, Y.

    2011-01-01T23:59:59.000Z

    Carbide-derived carbons (CDCs) are a large family of carbon materials derived from carbide precursors that are transformed into pure carbon via physical (e.g., thermal decomposition) or chemical (e.g., halogenation) processes. Structurally, CDC ranges from amorphous carbon to graphite, carbon nanotubes or graphene. For halogenated carbides, a high level of control over the resulting amorphous porous carbon structure is possible by changing the synthesis conditions and carbide precursor. The large number of resulting carbon structures and their tunability enables a wide range of applications, from tribological coatings for ceramics, or selective sorbents, to gas and electrical energy storage. In particular, the application of CDC in supercapacitors has recently attracted much attention. This review paper summarizes key aspects of CDC synthesis, properties, and applications. It is shown that the CDC structure and properties are sensitive to changes of the synthesis parameters. Understanding of processing–structure–properties relationships facilitates tuning of the carbon material to the requirements of a certain application.

  15. Additive-assisted synthesis of boride, carbide, and nitride micro/nanocrystals

    SciTech Connect (OSTI)

    Chen, Bo [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)] [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China); Yang, Lishan [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Shandong University), Ministry of Education, and School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)] [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Shandong University), Ministry of Education, and School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Heng, Hua; Chen, Jingzhong; Zhang, Linfei; Xu, Liqiang [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)] [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China); Qian, Yitai, E-mail: ytqian@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)] [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China); Yang, Jian, E-mail: yangjian@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)] [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)

    2012-10-15T23:59:59.000Z

    General and simple methods for the syntheses of borides, carbides and nitrides are highly desirable, since those materials have unique physical properties and promising applications. Here, a series of boride (TiB{sub 2}, ZrB{sub 2}, NbB{sub 2}, CeB{sub 6}, PrB{sub 6}, SmB{sub 6}, EuB{sub 6}, LaB{sub 6}), carbide (SiC, TiC, NbC, WC) and nitride (TiN, BN, AlN, MgSiN{sub 2}, VN) micro/nanocrystals were prepared from related oxides and amorphous boron/active carbon/NaN{sub 3} with the assistance of metallic Na and elemental S. In-situ temperature monitoring showed that the reaction temperature could increase quickly to {approx}850 Degree-Sign C, once the autoclave was heated to 100 Degree-Sign C. Such a rapid temperature increase was attributed to the intense exothermic reaction between Na and S, which assisted the formation of borides, carbides and nitrides. The as-obtained products were characterized by XRD, SEM, TEM, and HRTEM techniques. Results in this report will greatly benefit the future extension of this approach to other compounds. - Graphical abstract: An additive-assisted approach is successfully developed for the syntheses of borides, carbides and nitrides micro/nanocrystals with the assistance of the exothermic reaction between Na and S. Highlights: Black-Right-Pointing-Pointer An additive-assisted synthesis strategy is developed for a number of borides, carbides and nitrides. Black-Right-Pointing-Pointer The reaction mechanism is demonstrated by the case of SiC nanowires. Black-Right-Pointing-Pointer The formation of SiC nanowires is initiated by the exothermic reaction of Na and S.

  16. Composition optimization of self-lubricating chromium carbide-based composite coatings for use to 760/sup 0/C

    SciTech Connect (OSTI)

    DellaCorte, C.; Sliney, H.E.

    1986-01-01T23:59:59.000Z

    This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the ''base stock'' because of the known excellent wear resistance and the chemical stability of chromium carbide. ''Additives'' were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a termary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto a superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760/sup 0/C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

  17. Elastic properties of B-C-N films grown by N{sub 2}-reactive sputtering from boron carbide targets

    SciTech Connect (OSTI)

    Salas, E.; Jiménez Riobóo, R. J.; Jiménez-Villacorta, F.; Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain)] [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain); Sánchez-Marcos, J. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain) [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain); Dept. Química-Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Muñoz-Martín, A.; Prieto, J. E.; Joco, V. [Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)] [Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2013-12-07T23:59:59.000Z

    Boron-carbon-nitrogen films were grown by RF reactive sputtering from a B{sub 4}C target and N{sub 2} as reactive gas. The films present phase segregation and are mechanically softer than boron carbide films (a factor of more than 2 in Young's modulus). This fact can turn out as an advantage in order to select buffer layers to better anchor boron carbide films on substrates eliminating thermally induced mechanical tensions.

  18. Tribological evaluation of high-speed steels with a regulated carbide phase

    SciTech Connect (OSTI)

    Richter, Janusz

    2003-06-15T23:59:59.000Z

    Wear resistance of a commercial steel and titanium-niobium high-speed steels with a regulated carbide phase was evaluated by employing a micro-scale abrasive wear test with alumina particles. The worn volumes and corresponding wear coefficients were the lowest for the new non-ledeburitic grades containing titanium, then the two niobium grades, the conventional (both wrought and by powder metallurgy) steels exhibited the worse wear resistance. Fractography SEM observations together with energy-dispersive X-ray (EDX) chemical analysis revealed the decisive role of the steels' MC particles in the wear process. These carbides influenced the abrasion by stoppage of the wear scars and/or changing their trajectories. Directional and nondirectional abrasion modes in the steels tested using alumina and carborundum abrasives were found and are discussed.

  19. Nonlinear-optical and structural properties of nanocrystalline silicon carbide films

    SciTech Connect (OSTI)

    Brodyn, M. S.; Volkov, V. I., E-mail: volkov@iop.kiev.ua; Lyakhovetskii, V. R.; Rudenko, V. I. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine); Puzilkov, V. M.; Semenov, A. V. [National Academy of Sciences of Ukraine, Institute of Monocrystals (Ukraine)

    2012-02-15T23:59:59.000Z

    The aim of this study is to investigate the nonlinearity of refraction in nanostructured silicon carbide films depending on their structural features (synthesis conditions for such films, substrate temperature during their deposition, concentration of the crystalline phase in the film, Si/C ratio of atomic concentrations in the film, and size of SiC nanocrystals formed in the film). The corresponding dependences are obtained, as well as the values of nonlinear-optical third-order susceptibility {chi}{sup (3)}({omega}; {omega}, -{omega}, {omega}) for various silicon polytypes (3C, 21R, and 27R) which exceed the value of {chi}{sup (3)} in bulk silicon carbide single crystals by four orders of magnitude.

  20. Modeling the formation of boron carbide particles in an aerosol flow reactor

    SciTech Connect (OSTI)

    Xiong, Y.; Pratsinis, S.E. (Dept. of Chemical Engineering, Center for Aerosol Processes, Univ. of Cincinnati, Cincinnati, OH (United States)); Weimer, A.W. (Ceramics and Advanced Materials Research, Dow Chemical U.S.A., Midland, MI (United States))

    1992-11-01T23:59:59.000Z

    In this paper the formation of submicron crystals of boron carbide (B[sub 4]C) by coagulation and sintering by the rapid carbothermal reduction of intimately mixed carbon-boron oxide powders in an aerosol flow reactor at temperatures above the boiling point of boron oxide is investigated. High heating rates (10[sup 5] K/s) force rapid evaporation of boron oxide and suboxides from the precursor powder, resulting in its rupture and formation of boron carbide molecular clusters that grow to macroscopic particles by coagulation. Consequently, the formation and growth of B[sub 4]C particles are described by simultaneous interparticle collision and coalescence using a two-dimensional particle-size distribution model that traces the evolution of both size and shape characteristics of the particles through their volume and surface area. In addition to the coagulation term, the governing population balance equation includes a coalescence contribution based on B[sub 4]C sintering law.

  1. Photonic Crystal Cavities in Cubic (3C) Polytype Silicon Carbide Films

    E-Print Network [OSTI]

    Marina Radulaski; Thomas M. Babinec; Sonia Buckley; Armand Rundquist; J Provine; Kassem Alassaad; Gabriel Ferro; Jelena Vu?kovi?

    2013-11-30T23:59:59.000Z

    We present the design, fabrication, and characterization of high quality factor and small mode volume planar photonic crystal cavities from cubic (3C) thin films (thickness ~ 200 nm) of silicon carbide (SiC) grown epitaxially on a silicon substrate. We demonstrate cavity resonances across the telecommunications band, with wavelengths from 1,250 - 1,600 nm. Finally, we discuss possible applications in nonlinear optics, optical interconnects, and quantum information science.

  2. Ceramic composites reinforced with modified silicon carbide whiskers and method for modifying the whiskers

    DOE Patents [OSTI]

    Tiegs, Terry N. (Lenoir City, TN); Lindemer, Terrence B. (Oak Ridge, TN)

    1991-01-01T23:59:59.000Z

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  3. Ceramic composites reinforced with modified silicon carbide whiskers and method for modifying the whiskers

    DOE Patents [OSTI]

    Tiegs, T.N.; Lindemer, T.B.

    1991-02-19T23:59:59.000Z

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  4. Rf-plasma synthesis of nanosize silicon carbide and nitride. Final report

    SciTech Connect (OSTI)

    Buss, R.J.

    1997-02-01T23:59:59.000Z

    A pulsed rf plasma technique is capable of generating ceramic particles of 10 manometer dimension. Experiments using silane/ammonia and trimethylchlorosilane/hydrogen gas mixtures show that both silicon nitride and silicon carbide powders can be synthesized with control of the average particle diameter from 7 to 200 nm. Large size dispersion and much agglomeration appear characteristic of the method, in contrast to results reported by another research group. The as produced powders have a high hydrogen content and are air and moisture sensitive. Post-plasma treatment in a controlled atmosphere at elevated temperature (800{degrees}C) eliminates the hydrogen and stabilizes the powder with respect to oxidation or hydrolysis.

  5. High temperature erosion and fatigue resistance of a detonation gun chromium carbide coating for steam turbines

    SciTech Connect (OSTI)

    Quets, J.M.; Walsh, P.N. [Praxair Surface Technologies, Inc., Indianapolis, IN (United States); Srinivasan, V. [Westinghouse Electric Corp., Orlando, FL (United States); Tucker, R.C. Jr. [Praxair Surface Technologies, Inc., Indianapolis, IN (United States)

    1994-12-31T23:59:59.000Z

    Chromium carbide based detonation gun coatings have been shown to be capable of protecting steam turbine components from particle erosion. To be usable, however, erosion resistant coatings must not degrade the fatigue characteristics of the coated components. Recent studies of the fatigue properties of a detonation gun coated martensitic substrate at 538 C (1,000 F) will be presented with an emphasis on its long term performance. This study will show the retention of acceptable fatigue performance of coated substrates into the high cycle regime, and will include a discussion on the mechanism of fatigue.

  6. Excitation and recombination dynamics of vacancy-related spin centers in silicon carbide

    SciTech Connect (OSTI)

    Hain, T. C.; Hertel, T. [Institute of Physical and Theoretical Chemistry, Julius-Maximilian University of Würzburg, 97074 Würzburg (Germany); Fuchs, F.; Astakhov, G. V., E-mail: astakhov@physik.uni-wuerzburg.de [Experimental Physics VI, Julius-Maximilian University of Würzburg, 97074 Würzburg (Germany); Soltamov, V. A. [Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); Baranov, P. G. [Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); St. Petersburg State Polytechnical University, 195251 St. Petersburg (Russian Federation); Dyakonov, V., E-mail: dyakonov@physik.uni-wuerzburg.de [Experimental Physics VI, Julius-Maximilian University of Würzburg, 97074 Würzburg (Germany); Bavarian Center for Applied Energy Research (ZAE Bayern), 97074 Würzburg (Germany)

    2014-04-07T23:59:59.000Z

    We generate silicon vacancy related defects in high-quality epitaxial silicon carbide layers by means of electron irradiation. By controlling the irradiation fluence, the defect concentration is varied over several orders of magnitude. We establish the excitation profile for optical pumping of these defects and evaluate the optimum excitation wavelength of 770?nm. We also measure the photoluminescence dynamics at room temperature and find a monoexponential decay with a characteristic lifetime of 6.1?ns. The integrated photoluminescence intensity depends linear on the excitation power density up to 20?kW/cm{sup 2}, indicating a relatively small absorption cross section of these defects.

  7. Fact Sheet: Award-Winning Silicon Carbide Power Electronics (October 2012)

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't YourTransport in RepresentativeDepartment ofDepartmentLast TenPrice of|SNL OnSilicon Carbide|

  8. Phase evolution in carbide dispersion strengthened nanostructured copper composite by high energy ball milling

    SciTech Connect (OSTI)

    Hussain, Zuhailawati; Nur Hawadah, M. S. [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2012-09-06T23:59:59.000Z

    In this study, high-energy ball milling was applied to synthesis in situ nanostructured copper based composite reinforced with metal carbides. Cu, M (M=W or Ti) and graphite powder mixture were mechanically alloyed for various milling time in a planetary ball mill with composition of Cu-20vol%WC and Cu-20vol%TiC. Then the as-milled powder were compacted at 200 to 400 MPa and sintered in a vacuum furnace at 900 Degree-Sign C. The results of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis showed that formation of tungsten carbides (W{sub 2}C and WC phases) was observed after sintering of Cu-W-C mixture while TiC precipitated in as-milled powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling. Mechanism of MA explained the cold welding and fracturing event during milling. Cu-W-C system shows fracturing event is more dominant at early stage of milling and W particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is more dominant and all Ti particles dissolved into Cu matrix.

  9. Method for fracturing silicon-carbide coatings on nuclear-fuel particles

    DOE Patents [OSTI]

    Turner, Lloyd J. (Oak Ridge, TN); Willey, Melvin G. (Knoxville, TN); Tiegs, Sue M. (Lenoir City, TN); Van Cleve, Jr., John E. (Kingston, TN)

    1982-01-01T23:59:59.000Z

    This invention is a device for fracturing particles. It is designed especially for use in "hot cells" designed for the handling of radioactive materials. In a typical application, the device is used to fracture a hard silicon-carbide coating present on carbon-matrix microspheres containing nuclear-fuel material, such as uranium or thorium compounds. To promote remote control and facilitate maintenance, the particle breaker is pneumatically operated and contains no moving parts. It includes means for serially entraining the entrained particles on an anvil housed in a leak-tight chamber. The flow rate of the gas is at a value effecting fracture of the particles; preferably, it is at a value fracturing them into product particulates of fluidizable size. The chamber is provided with an outlet passage whose cross-sectional area decreases in the direction away from the chamber. The outlet is connected tangentially to a vertically oriented vortex-flow separator for recovering the product particulates entrained in the gas outflow from the chamber. The invention can be used on a batch or continuous basis to fracture the silicon-carbide coatings on virtually all of the particles fed thereto.

  10. Fort Saint Vrain HTGR (Th/U carbide) Fuel Characteristics for Disposal Criticality Analysis

    SciTech Connect (OSTI)

    Taylor, Larry Lorin

    2001-01-01T23:59:59.000Z

    DOE-owned spent nuclear fuels encompass many fuel types. In an effort to facilitate criticality analysis for these various fuel types, they were categorized into eight characteristic fuel groups with emphasis on fuel matrix composition. Out of each fuel group, a representative fuel type was chosen for analysis as a bounding case within that fuel group. Generally, burnup data, fissile enrichments and total fuel mass govern the selection of the representative or candidate fuel within that group. For the HTGR group, the Fort Saint Vrain (FSV) reactor fuel has been chosen for the evaluation of viability for waste co-disposal. The FSV reactor was operated by Public Service of Colorado as a licensed power reactor. The FSV fuel employs a U/Th carbide matrix in individually pyrolytic carbon-coated particles. These individual particles are in turn coated with silicon carbide (SiC) and contained within fuel compacts, that are in turn embedded in graphite blocks that comprised the structural core of the reactor.

  11. IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 58, NO. 1, JANUARY 2011 21 Efficiency Impact of Silicon Carbide Power

    E-Print Network [OSTI]

    Tolbert, Leon M.

    ), silicon carbide (SiC), wind generation. I. INTRODUCTION VARIABLE speed capability allows a wind turbine to operate at speeds which produce the greatest amount of power and minimizes torque perturbations the voltage and frequency of the generated power vary with the turbine speed, a converter is required

  12. Accuracy of truncated Leiden and Berlin virial expansions for pure gases and sealing joints between silicon carbide and stainless steel

    E-Print Network [OSTI]

    Santana Rodriguez, Gabriel Enrique

    2003-01-01T23:59:59.000Z

    carbide to steel were studied. Brazing is the technique more used, and several active filler metals such as Ag-Cu-In-Ti, Ag-Cu-Ti, plus carbon fibers Ag-Cu-Hf and Niobium were used. This review shows that the strength of the joint is affected by the amount...

  13. Structural and electronic properties of cobalt carbide Co2C and its surface stability: Density functional theory study

    E-Print Network [OSTI]

    Li, Weixue

    in Fischer­Tropsch syn- thesis, which agrees well with experimental findings. The density of states (DOSs­14], dehydrogenation [15], hydrogenolysis [16, 17] and Fischer­Tropsch synthesis (FTS) [18­22] etc., approaching activity of cobalt, iron and iron carbide in Fischer­Tropsch synthesis (FTS)[24­43], relative little

  14. Deposition of silicon carbide films using a high vacuum metalorganic chemical vapor deposition method with a single source precursor

    E-Print Network [OSTI]

    Boo, Jin-Hyo

    , high temperature, and high radiation environments. Conventional silicon carbide chemical vapor deposition CVD processes generally utilized multiple precursors such as silane and hydrocarbons, and required temperature alternatives to the conventional SiC CVD methods must be considered. To do this, a relatively

  15. Development of a Commercial Process for the Production of Silicon Carbide Fibrils

    SciTech Connect (OSTI)

    Nixdorf, R.D.

    1999-04-01T23:59:59.000Z

    A patent was issued on ''VLS'' silicon carbide fibrils to North American Phillips Corporation in 1975. Various laboratories and companies have been attempting to improve this process and scale it to larger quantities since that time. All of these efforts met with minimal success because they were using the original technology while attempting to improve the equipment. The principal impediments have been: (1) Slow crystal growth during fibril production; (2) Sensitive stoichiometry factors in the crystal growth chamber; and (3) Precise control of a high temperature process. The principal investigator has scaled silicon carbide whisker production at American Matrix and the SiC fiber process at Advanced Composite Materials Corporation from grams in the laboratory to tons per year production. This project is a proof-of-concept effort to apply some of the recent technology to the problems listed above in the fibril growth process. Two different technology approaches were investigated. A major problem with fibril growth has been generating a consistent supply of the required SiO gas reactant, which is a product of reducing SiO{sub 2}. The first approach, in this project addresses the SiO gas production, involved mixing silica and carbon fibrous raw materials in the immediate proximity of the graphite fibril growth plates to generate SiO nearer to individual sites of fibril growth. Iron bearing catalyst was painted on the graphite plates and the SiO generator mix was placed above the plate. This system was then heated to 1600/1650 C in a graphite resistance furnace. Some fibrils were started but the growth rate and fibril quality were unacceptably low. A second approach, which uses MTS + H{sub 2} gases to address stoichiometry control, was investigated to improve fibril growth rates while reducing the previous high temperature requirements for the process. A partial vacuum chamber was construct inside a commercial microwave furnace. The fibril growth container was coated with an iron catalyst and brought to 1200 C by the microwave field. A mixture of hydrogen and methyl trichlorosilane gases were fed to the fibril reaction container. Excellent silicon carbide fibrils were produced at a growth rate that was over four times greater than previously reported processes. The next phase of the development will be an optimization of operating parameters to improve fibril yield in the microwave growth process. The development activities will then move to the construction and testing of a pilot unit.

  16. Quantum Chemistry, and Eclectic Mix: From Silicon Carbide to Size Consistency

    SciTech Connect (OSTI)

    Jamie Marie Rintelman

    2004-12-19T23:59:59.000Z

    Chemistry is a field of great breadth and variety. It is this diversity that makes for both an interesting and challenging field. My interests have spanned three major areas of theoretical chemistry: applications, method development, and method evaluation. The topics presented in this thesis are as follows: (1) a multi-reference study of the geometries and relative energies of four atom silicon carbide clusters in the gas phase; (2) the reaction of acetylene on the Si(100)-(2x1) surface; (3) an improvement to the Effective Fragment Potential (EFP) solvent model to enable the study of reactions in both aqueous and nonaqueous solution; and (4) an evaluation of the size consistency of Multireference Perturbation Theory (MRPT). In the following section, the author briefly discusses two topics central to, and present throughout, this thesis: Multi-reference methods and Quantum Mechanics/Molecular Mechanics (QM/MM) methods.

  17. Joining of silicon carbide using interlayer with matching coefficient of thermal expansion

    SciTech Connect (OSTI)

    Perham, T. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering; [Lawrence Berkeley National Lab., CA (United States)

    1996-11-01T23:59:59.000Z

    The primary objective of this study is to develop a technique for joining a commercially available Silicon Carbide that gives good room temperature strength and the potential for good high temperature strength. One secondary objective is that the joining technique be adaptable to SiC{sub f}/SiC composites and/or Nickel based superalloys, and another secondary objective is that the materials provide good neutron irradiation resistance and low activation for potential application inside nuclear fusion reactors. The joining techniques studied here are: (1) reaction bonding with Al-Si/Si/SiC/C; (2) reaction/infiltration with calcium aluminum silicate; (3) ion exchange mechanism to form calcium hexaluminate (a refractory cement); and (4) oxide frit brazing with cordierite.

  18. Visible Photoluminescence from Cubic (3C) Silicon Carbide Microdisks Coupled to High Quality Whispering Gallery Modes

    E-Print Network [OSTI]

    Marina Radulaski; Thomas M. Babinec; Kai Müller; Konstantinos G. Lagoudakis; Jingyuan Linda Zhang; Sonia Buckley; Yousif A. Kelaita; Kassem Alassaad; Gabriel Ferro; Jelena Vu?kovi?

    2014-12-08T23:59:59.000Z

    We present the design, fabrication and characterization of cubic (3C) silicon carbide microdisk resonators with high quality factor modes at visible and near infrared wavelengths (600 - 950 nm). Whispering gallery modes with quality factors as high as 2,300 and corresponding mode volumes V ~ 2 ({\\lambda}/n)^3 are measured using laser scanning confocal microscopy at room temperature. We obtain excellent correspondence between transverse-magnetic (TM) and transverse-electric (TE) polarized resonances simulated using Finite Difference Time Domain (FDTD) method and those observed in experiment. These structures based on ensembles of optically active impurities in 3C-SiC resonators could play an important role in diverse applications of nonlinear and quantum photonics, including low power optical switching and quantum memories.

  19. .beta.-silicon carbide protective coating and method for fabricating same

    DOE Patents [OSTI]

    Carey, Paul G. (Mountain View, CA); Thompson, Jesse B. (Brentwood, CA)

    1994-01-01T23:59:59.000Z

    A polycrystalline beta-silicon carbide film or coating and method for forming same on components, such as the top of solar cells, to act as an extremely hard protective surface, and as an anti-reflective coating. This is achieved by DC magnetron co-sputtering of amorphous silicon and carbon to form a SiC thin film onto a surface, such as a solar cell. The thin film is then irradiated by a pulsed energy source, such as an excimer laser, to synthesize the poly- or .mu.c-SiC film on the surface and produce .beta.--SiC. While the method of this invention has primary application in solar cell manufacturing, it has application wherever there is a requirement for an extremely hard surface.

  20. [beta]-silicon carbide protective coating and method for fabricating same

    DOE Patents [OSTI]

    Carey, P.G.; Thompson, J.B.

    1994-11-01T23:59:59.000Z

    A polycrystalline beta-silicon carbide film or coating and method for forming same on components, such as the top of solar cells, to act as an extremely hard protective surface, and as an anti-reflective coating are disclosed. This is achieved by DC magnetron co-sputtering of amorphous silicon and carbon to form a SiC thin film onto a surface, such as a solar cell. The thin film is then irradiated by a pulsed energy source, such as an excimer laser, to synthesize the poly- or [mu]c-SiC film on the surface and produce [beta]-SiC. While the method of this invention has primary application in solar cell manufacturing, it has application wherever there is a requirement for an extremely hard surface. 3 figs.

  1. Method for production of ceramic oxide and carbide bodies by polymer inclusion and decomposition

    DOE Patents [OSTI]

    Quinby, T.C.

    1984-08-30T23:59:59.000Z

    A method for the preparation of thin, free-standing metal oxide films which are useful as nuclear accelerator target materials is described. Cations of any metal except those of Group IA and precious metals, such as, U, Zr, Nd, Ce, Th, Pr or Cr, are absorbed on a thin film of polymeric material, such as carboxymethylcellulose, viscose rayon or cellophane. The cation impregnated polymeric material is dried. Then the impregnated film is heated in an inert atmosphere to form a carbonized membrane. The carbonized membrane is oxidized to yield a thin, self-supporting, metal oxide membrane. Or, the membrane can be heated in an inert atmosphere to yield a thin, self-supporting, metal carbide-containing membrane.

  2. Diorganosilacetylene-alt-diorganosilvinylene polymers and a process densifying porous silicon-carbide bodies

    DOE Patents [OSTI]

    Barton, T.J.; Ijadi-Maghsoodi, S.; Pang, Y.

    1994-05-17T23:59:59.000Z

    The present invention provides linear organosilicon polymers including acetylene and vinylene moieties, and a process for their preparation. These diorganosilacetylene-alt-diorganosilvinylene linear polymers can be represented by the formula: --[--(R[sup 1])(R[sup 2])Si--C[triple bond]C-(R[sup 3])(R[sup 4])Si--CH[double bond]CH--][sub n]--, wherein n[>=]2; and each R[sup 1], R[sup 2], R[sup 3], and R[sup 4] is independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, aryl, and aralkyl radicals. The polymers are soluble in organic solvents, air stable, and can be pulled into fibers or cast into films. They can be thermally converted into silicon carbide ceramic materials.

  3. A comprehensive study of thermoelectric and transport properties of ?-silicon carbide nanowires

    SciTech Connect (OSTI)

    Valentín, L. A.; Betancourt, J.; Fonseca, L. F., E-mail: luis.fonseca@upr.edu [Department of Physics University of Puerto Rico, Rio Piedras (Puerto Rico); Pettes, M. T.; Shi, L. [Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712 (United States); Soszy?ski, M.; Huczko, A. [Department of Chemistry, Warsaw University, Pasteur 1 Str., 02-093 Warsaw (Poland)

    2013-11-14T23:59:59.000Z

    The temperature dependence of the Seebeck coefficient, the electrical and thermal conductivities of individual ?-silicon carbide nanowires produced by combustion in a calorimetric bomb were studied using a suspended micro-resistance thermometry device that allows four-point probe measurements to be conducted on each nanowire. Additionally, crystal structure and growth direction for each measured nanowire was directly obtained by transmission electron microscopy analysis. The Fermi level, the carrier concentration, and mobility of each nanostructure were determined using a combination of Seebeck coefficient and electrical conductivity measurements, energy band structure and transport theory calculations. The temperature dependence of the thermal and electrical conductivities of the nanowires was explained in terms of contributions from boundary, impurity, and defect scattering.

  4. The effects of erodent particle size and composition on the erosion of chromium carbide based coatings

    SciTech Connect (OSTI)

    Walsh, P.N.; Quets, J.M.; Tucker, R.C. Jr. [Praxair Surface Technologies, Inc., Indianapolis, IN (United States)

    1994-12-31T23:59:59.000Z

    A number of studies and field experience have demonstrated the efficacy of use of chromium carbide based coatings on steam turbine components to reduce the effects of solid particle erosion. To optimize the performance of these coatings, a cost effective laboratory test is needed to facilitate the choice of coating composition, morphology, and deposition method. A variety of test types and test parameters have been reported with varying relative rankings of the various coatings evaluated. A critical review of past work has been made, with new data added for clarification. The particle size of the erodent used as well as its composition has been shown to be of particular importance. A correlation between field experience and selected laboratory test parameters then facilitates the optimum choice of coatings.

  5. Cryochemical and CVD processing of shperical carbide fuels for propulsion reactors

    SciTech Connect (OSTI)

    Blair, H.T.; Carroll, D.W.; Matthews, R.B. (Los Alamos National Laboratory, MS E505, Los Alamos, New Mexico (USA))

    1991-01-10T23:59:59.000Z

    Many of the nuclear propulsion reactor concepts proposed for a manned mission to Mars use a coated spherical particle fuel form similar to that used in the Rover and NERVA propulsion reactors. The formation of uranium dicarbide microspheres using a cryochemical process and the coating of the UC{sub 2} spheres with zirconium carbide using chemical vapor deposition are being developed at Los Alamos National Laboratory. The cryochemical process is described with a discussion of the variables affecting the sphere formation and carbothermic reduction to produce UC{sub 2} spheres from UO{sub 2}. Emphasis is placed on minimizing the wastes produced by the process. The ability to coat particles with ZrC was recaptured, and improvements in the process and equipment were developed. Volatile organometallic precursors were investigated as alternatives to the original ZrCl{sub 4} precursor.

  6. A review of carbide fuel corrosion for nuclear thermal propulsion applications

    SciTech Connect (OSTI)

    Pelaccio, D.G.; El-Genk, M.S. [Univ. of New Mexico, Albuquerque, NM (United States). Inst. for Space Nuclear Power Studies; Butt, D.P. [Los Alamos National Lab., NM (United States)

    1993-12-01T23:59:59.000Z

    At the operation conditions of interest in nuclear thermal propulsion reactors, carbide materials have been known to exhibit a number of life limiting phenomena. These include the formation of liquid, loss by vaporization, creep and corresponding gas flow restrictions, and local corrosion and fuel structure degradation due to excessive mechanical and/or thermal loading. In addition, the radiation environment in the reactor core can produce a substantial change in its local physical properties, which can produce high thermal stresses and corresponding stress fractures (cracking). Time-temperature history and cyclic operation of the nuclear reactor can also accelerate some of these processes. The University of New Mexico`s Institute for Space Nuclear Power Studies, under NASA sponsorship has recently initiated a study to model the complicated hydrogen corrosion process. In support of this effort, an extensive review of the open literature was performed, and a technical expert workshop was conducted. This paper summarizes the results of this review.

  7. Monocrystalline silicon carbide nanoelectromechanical systems Y. T. Yang, K. L. Ekinci, X. M. H. Huang, L. M. Schiavone, and M. L. Roukesa)

    E-Print Network [OSTI]

    Roukes, Michael L.

    C devices have primarily been fabricated from polycrystalline 3C-SiC poly-SiC thin films deposited diMonocrystalline silicon carbide nanoelectromechanical systems Y. T. Yang, K. L. Ekinci, X. M. H

  8. Separate determination of the amplitude of thermal vibrations and static atomic displacements in titanium carbide by neutron diffraction

    SciTech Connect (OSTI)

    Khidirov, I., E-mail: khidirov@inp.uz; Parpiev, A. S. [Uzbekistan Academy of Sciences, Institute of Nuclear Physics (Uzbekistan)

    2011-05-15T23:59:59.000Z

    The amplitude of thermal (dynamic) atomic vibrations and meansquare static atomic displacements in titanium carbide TiC{sub x} (x = 0.97, 0.88, 0.70) have been separately determined by measuring neutron diffraction patterns at two temperatures (T{sub 1} = 300 K and T{sub 2} = 80 K). The static lattice distortions in stoichiometric titanium carbide are experimentally found to be negligible. In the TiC{sub x} homogeneity range, the amplitude {radical}u{sup 2}{sub dyn} of thermal atomic vibrations significantly increases with a decrease in the carbon concentration. The Debye temperature has been determined for the first time in the TiC{sub x} homogeneity range at both room and liquid-nitrogen temperatures.

  9. Technical Review Report for the Justification for Shipment of Sodium-Bonded Carbide Fuel Pins in the T-3 Cask

    SciTech Connect (OSTI)

    West, M; DiSabatino, A

    2008-01-04T23:59:59.000Z

    This report documents the review of the Fluor Submittal (hereafter, the Submittal), prepared by Savannah River Packaging Technology (SRPT) of Savannah River National Laboratory (SRNL), at the request of the Department of Energy's (DOE) Richland Operations Office, for the shipment of unirradiated and irradiated sodium-bonded carbide fuel pins. The sodium-bonded carbide fuel pins are currently stored at the Fast Flux Test Facility (FFTF) awaiting shipment to Idaho National Laboratory (INL). Normally, modified contents are included into the next revision of the SARP. However, the contents, identified to be shipped from FFTF to Idaho National Laboratory, are a one-way shipment of 18 irradiated fuel pins and 7 unirradiated fuel pins, where the irradiated and unirradiated fuel pins are shipped separately, and can be authorized with a letter amendment to the existing Certificate of Compliance (CoC).

  10. Radiation-tolerant joining technologies for silicon carbide ceramics and composites

    SciTech Connect (OSTI)

    Katoh, Yutai; Snead, Lance L.; Cheng, Ting; Shih, Chunghao; Lewis, W. Daniel; Koyanagi, Takaaki; Hinoki, Tetsuya; Henager, Charles H.; Ferraris, Monica

    2014-05-01T23:59:59.000Z

    Silicon carbide (SiC) for nuclear structural applications, whether in the monolithic ceramic or composite form, will require a robust joining technology capable of withstanding the harsh nuclear environment. This paper presents significant progress made towards identifying and processing irradiation-tolerant joining methods for nuclear-grade SiC. In doing so, a standardized methodology for carrying out joint testing has been established consistent with the small volume samples mandated by neutron irradiation testing. Candidate joining technologies were limited to those that provide low induced radioactivity and included titanium diffusion bonding, Ti–Si–C MAX-phase joining, calcia–alumina glass–ceramic joining, and transient eutectic-phase SiC joining. Samples of these joints were irradiated in the Oak Ridge National Laboratory High Flux Isotope Reactor at 500 or 800 ?C, and their microstructure and mechanical properties were compared to pre-irradiation conditions. Within the limitations of statistics, all joining methodologies presented retained their joint mechanical strength to 3 dpa at 500 ?C, thus indicating the first results obtained on irradiation-stable SiC joints. Under the more aggressive irradiation conditions (800 ?C, 5 dpa), some joint materials exhibited significant irradiation-induced microstructural evolution; however, the effect of irradiation on joint strength appeared rather limited.

  11. Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

    DOE Patents [OSTI]

    McCallum, R. William (Ames, IA); Branagan, Daniel J. (Ames, IA)

    1996-01-23T23:59:59.000Z

    A method of making a permanent magnet wherein 1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and 2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties.

  12. An investigation of silicon carbide-water nanofluid for heat transfer applications.

    SciTech Connect (OSTI)

    Singh, D.; Timofeeva, E.; Yu, W.; Routbort, J.; France, D.; Smith, D.; Lopez-Cepero, J. M. (Energy Systems); ( NE)

    2009-03-15T23:59:59.000Z

    Thermal conductivity and mechanical effects of silicon carbide nanoparticles uniformly dispersed in water were investigated. Mean size of SiC particles was 170 nm with a polydispersity of {approx}30% as determined from small-angle x-ray scattering and dynamic light scattering techniques. Room temperature viscosity of the nanofluids ranged from 2 to 3 cP for nominal nanoparticle loadings 4-7 vol %. On a normalized basis with water, viscosity of the nanofluids did not significantly change with the test temperature up to 85 C. Optical microscopy of diluted nanofluid showed no agglomeration of the nanoparticles. Thermal conductivity of the fluid was measured as a function of the nominal nanoparticle loading ranging from 1 to 7 vol %. Enhancement in thermal conductivity was approximately 28% over that of water at 7 vol % particle loadings under ambient conditions. Enhancements in thermal conductivities for the nanofluids with varying nanoparticle loadings were maintained at test temperatures up to 70 C. Results of thermal conductivity have been rationalized based on the existing theories of heat transfer in fluids. Implications of using this nanofluid for engineering cooling applications are discussed.

  13. Magnesium behavior and structural defects in Mg+ ion implanted silicon carbide

    SciTech Connect (OSTI)

    Jiang, Weilin; Jung, Hee Joon; Kovarik, Libor; Wang, Zhaoying; Roosendaal, Timothy J.; Zhu, Zihua; Edwards, Danny J.; Hu, Shenyang Y.; Henager, Charles H.; Kurtz, Richard J.; Wang, Yongqiang

    2015-01-01T23:59:59.000Z

    As a candidate material for fusion reactor applications, silicon carbide (SiC) undergoes transmutation reactions under high-energy neutron irradiation with magnesium as the major metallic transmutant; the others include aluminum, beryllium and phosphorus in addition to helium and hydrogen gaseous species. The impact of these transmutants on SiC structural stability is currently unknown. This study uses ion implantation to introduce Mg into SiC. Multiaxial ion-channeling analysis of the as-produced damage state suggests that there are preferred Si <100> interstitial splits. The microstructure of the annealed sample was examined using high-resolution scanning transmission electron microscopy. The results show a high concentration of likely non-faulted tetrahedral voids and possible stacking fault tetrahedra near the damage peak. In addition to lattice distortion, dislocations and intrinsic and extrinsic stacking faults are also observed. Magnesium in 3C-SiC prefers to substitute for Si and it forms precipitates of cubic Mg2Si and tetragonal MgC2. The diffusion coefficient of Mg in 3C-SiC single crystal at 1573 K has been determined to be 3.8±0.4×10e-19 m2/sec.

  14. Fission Yield Measurements from Highly Enriched Uranium Irradiated Inside a Boron Carbide Capsule

    SciTech Connect (OSTI)

    Metz, Lori A.; Friese, Judah I.; Finn, Erin C.; Greenwood, Lawrence R.; Kephart, Rosara F.; Hines, Corey C.; King, Matthew D.; Henry, Kelley; Wall, Donald E.

    2013-05-01T23:59:59.000Z

    A boron carbide capsule was previously designed and tested by Pacific Northwest National Laboratory (PNNL) and Washington State University (WSU) for spectral-tailoring in mixed spectrum reactors. The presented work used this B4C capsule to create a fission product sample from the irradiation of highly enriched uranium (HEU) with a fast fission neutron spectrum. An HEU foil was irradiated inside of the capsule in WSU’s 1 MW TRIGA reactor at full power for 200 min to produce 5.8 × 1013 fissions. After three days of cooling, the sample was shipped to PNNL for radiochemical separations and analysis by gamma and beta spectroscopy. Fission yields for products were calculated from the radiometric measurements and compared to measurements from thermal neutron induced fission (analyzed in parallel with the non-thermal sample at PNNL) and published evaluated fast-pooled and thermal nuclear data. Reactor dosimetry measurements were also completed to fully characterize the neutron spectrum and total fluence of the irradiation.

  15. Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

    DOE Patents [OSTI]

    McCallum, R.W.; Branagan, D.J.

    1996-01-23T23:59:59.000Z

    A method of making a permanent magnet is disclosed wherein (1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and (2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties. 33 figs.

  16. Light Water Reactor Sustainability Program Status of Silicon Carbide Joining Technology Development

    SciTech Connect (OSTI)

    Shannon M. Bragg-Sitton

    2013-09-01T23:59:59.000Z

    Advanced, accident tolerant nuclear fuel systems are currently being investigated for potential application in currently operating light water reactors (LWR) or in reactors that have attained design certification. Evaluation of potential options for accident tolerant nuclear fuel systems point to the potential benefits of silicon carbide (SiC) relative to Zr-based alloys, including increased corrosion resistance, reduced oxidation and heat of oxidation, and reduced hydrogen generation under steam attack (off-normal conditions). If demonstrated to be applicable in the intended LWR environment, SiC could be used in nuclear fuel cladding or other in-core structural components. Achieving a SiC-SiC joint that resists corrosion with hot, flowing water, is stable under irradiation and retains hermeticity is a significant challenge. This report summarizes the current status of SiC-SiC joint development work supported by the Department of Energy Light Water Reactor Sustainability Program. Significant progress has been made toward SiC-SiC joint development for nuclear service, but additional development and testing work (including irradiation testing) is still required to present a candidate joint for use in nuclear fuel cladding.

  17. Tritium trapping in silicon carbide in contact with solid breeder under high flux isotope reactor irradiation

    SciTech Connect (OSTI)

    H. Katsui; Y. Katoh; A. Hasegawa; M. Shimada; Y. Hatano; T. Hinoki; S. Nogami; T. Tanaka; S. Nagata; T. Shikama

    2013-11-01T23:59:59.000Z

    The trapping of tritium in silicon carbide (SiC) injected from ceramic breeding materials was examined via tritium measurements using imaging plate (IP) techniques. Monolithic SiC in contact with ternary lithium oxide (lithium titanate and lithium aluminate) as a ceramic breeder was irradiated in the High Flux Isotope Reactor (HFIR) in Oak Ridge, Tennessee, USA. The distribution of photo-stimulated luminescence (PSL) of tritium in SiC was successfully obtained, which separated the contribution of 14C ß-rays to the PSL. The tritium incident from ceramic breeders was retained in the vicinity of the SiC surface even after irradiation at 1073 K over the duration of ~3000 h, while trapping of tritium was not observed in the bulk region. The PSL intensity near the SiC surface in contact with lithium titanate was higher than that obtained with lithium aluminate. The amount of the incident tritium and/or the formation of a Li2SiO3 phase on SiC due to the reaction with lithium aluminate under irradiation likely were responsible for this observation.

  18. Effect of Decreasing of Cobalt Content in Properties for Diamond/Cemented Carbide Tools

    SciTech Connect (OSTI)

    Waratta, A.; Hamdi, M. [Department of Design and Manufacture, Faculty of Engineering, University of Malaya (Malaysia); Ariga, T. [Department of Materials Science, School of Engineering, Tokai University (Japan)

    2010-03-11T23:59:59.000Z

    Powder metallurgy plays a role in manufacturing such as automotive and cutting tool applications. Diamond/cemented carbide tools are also made from this technique. Diamond particle and other matrix materials were employed in this study. The purpose is to investigate the physical and mechanical properties of different Cobalt (Co) content samples by using Taguchi's method. The materials used in the experiments were mixed by using a ball-mill machine. The mixed powders were pressed by conventional method. Then the green samples were sintered in a vacuum furnace. After reaching 500 deg. C, the samples were sintered with Argon (Ar) gas. The sintered samples were investigated density by immersion method, porosity by water saturation method, and hardness by Vicker hardness tester. It was found that with 59.5% Co content, plain diamond type, sintering temperature of 950 deg. C, sintering time of 40 minutes, and pressure of 625 MPa, density, porosity, and hardness got the best result in this study. From the Taguchi's analysis, the significant factors effected the performance were composition, sintering temperature, and sintering time.

  19. The Role of tantalum in TiC-WC-TaC-Co sintered carbides. II. influence of tantalum content on the structure and properties of TiC-WC-TaC-Co three-phase sintered carbides

    SciTech Connect (OSTI)

    Cheburaeva, R.F.; Chaporova, I.N.

    1986-10-01T23:59:59.000Z

    This work is devoted to a study of the influence of tantalum on the structure and properties of three-phase alloys. The investigations were made with a constant weight ratio of Ti:WC = 35:65% and an unchanged carbon content. The alloys were prepared by mixing of the (T, W, Ta)C carbides with cobalt and tungsten carbide. The pressed specimens were given a preliminary sinter in hydrogen at 923-973 K and a final one in a vacuum furnace at 1773 K. The microstructure, density, and bend and compressive strengths at room and increased temperatures, coeffiecients of cutting life and strength (in comparison with a standard taken as unity), and adhesion interaction were determined. The coefficient of cutting life was determined by transverse machining of steel. The coefficient of strength was determined by the method of breaking feed in milling of 50 steel with a single-tooth cutter. The adhesion interaction of TiC-WC-TaC-Co alloys with the material being machined (50 steel) was determined in vacuum (which eliminated the additional influence of oxidation of the alloy) at 873 K with a load of 1000N. Tantalum carbide additions have a favorable influence on the physicomechanical and service properties of TiC-WC-Co alloys. Their bend strength at room and increased temperatures increases and there is an increase in the total deformation and the work for deformation at increased temperatures, a reduction in oxidation and adhesion interaction with the material being machined, and a significant increase in wear resistance in cutting. Graphs and tables are included.

  20. Characterization of boron carbide particulate reinforced in situ copper surface composites synthesized using friction stir processing

    SciTech Connect (OSTI)

    Sathiskumar, R., E-mail: sathiscit2011@gmail.com [Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, 641 014 Tamil Nadu (India); Murugan, N., E-mail: murugan@cit.edu.in [Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, 641 014 Tamil Nadu (India); Dinaharan, I., E-mail: dinaweld2009@gmail.com [Department of Mechanical Engineering, V V College of Engineering, Tisaiyanvilai, 627 657 Tamil Nadu (India); Vijay, S.J., E-mail: vijayjoseph@karunya.edu [Centre for Research in Metallurgy (CRM), School of Mechanical Sciences, Karunya University, Coimbatore, 641 114 Tamil Nadu (India)

    2013-10-15T23:59:59.000Z

    Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B{sub 4}C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B{sub 4}C particles. The dimensions of the groove was varied to result in five different volume fractions of B{sub 4}C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B{sub 4}C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B{sub 4}C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B{sub 4}C surface composites. When the volume fraction of B{sub 4}C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer. Highlights: • Fabrication of Cu/B{sub 4}C surface composite by friction stir processing • Analyzing the effect of B{sub 4}C particles on the properties of Cu/B4C surface composite • Increased volume fraction of B{sub 4}C particles reduced the area of surface composite. • Increased volume fraction of B{sub 4}C particles enhanced the microhardness and wear rate. • B{sub 4}C particles altered the wear mode from microcutting to abrasive.

  1. Growth of silicon quantum dots by oxidation of the silicon nanocrystals embedded within silicon carbide matrix

    SciTech Connect (OSTI)

    Kole, Arindam; Chaudhuri, Partha, E-mail: erpc@iacs.res.in [Indian Association for the Cultivation of Science, 2A and 2B Raja S.C. Mullick Road, Jadavpur, Kolkata-700032 (India)

    2014-10-15T23:59:59.000Z

    A moderately low temperature (?800 °C) thermal processing technique has been described for the growth of the silicon quantum dots (Si-QD) within microcrystalline silicon carbide (?c-SiC:H) dielectric thin films deposited by plasma enhanced chemical vapour deposition (PECVD) process. The nanocrystalline silicon grains (nc-Si) present in the as deposited films were initially enhanced by aluminium induced crystallization (AIC) method in vacuum at a temperature of T{sub v} = 525 °C. The samples were then stepwise annealed at different temperatures T{sub a} in air ambient. Analysis of the films by FTIR and XPS reveal a rearrangement of the ?c-SiC:H network has taken place with a significant surface oxidation of the nc-Si domains upon annealing in air. The nc-Si grain size (D{sub XRD}) as calculated from the XRD peak widths using Scherrer formula was found to decrease from 7 nm to 4 nm with increase in T{sub a} from 250 °C to 800 °C. A core shell like structure with the nc-Si as the core and the surface oxide layer as the shell can clearly describe the situation. The results indicate that with the increase of the annealing temperature in air the oxide shell layer becomes thicker and the nc-Si cores become smaller until their size reduced to the order of the Si-QDs. Quantum confinement effect due to the SiO covered nc-Si grains of size about 4 nm resulted in a photoluminescence peak due to the Si QDs with peak energy at 1.8 eV.

  2. IMPACT EVALUATION OF AN ENERGY SAVINGS PLAN PROJECT AT THE LINDE DIVISION OF UNION CARBIDE CORPORATION

    SciTech Connect (OSTI)

    Spanner, G. E.; Sullivan, G. P.

    1992-04-01T23:59:59.000Z

    This impact evaluation of an energy conservation measure (ECM) that was recently installed at the Linde Division of Union Carbide Corporation (Linde) was conducted far the Bonneville Power Administration (Bonneville) as part of an evaluation of its Energy Savings Plan (ESP) Program. The Program makes acquisition payments to firms that install energy conservation measures in their industrial processes. The objective of this impact evaluation was to assess how much electrical energy is being saved at Linde as a result of the ESP and to determine how much the savings cost Bonneville and the region. The impact of the ECM was evaluated with a combination of engineering analysis, financial analysis, site visit and interviews, and submittal reviews (Linde's Completion Report and Abstract). The ECM itself consists of replacing the plant's nitrogen feed compressor with a larger unit, which allows the plant to meet its argon demand using less compressed air and which results in net energy savings. Energy savings resulting from this ECM were 4,376,500 kWh/yr for the first two years after installation, but, because of a change in Linde's market position, long-term savings are expected to be lower at 2,549,200 kWh/yr. Linde considers energy consumption and savings on a per ton basis to be proprietary, so they are not reported here. The ECM cost $361,4.96 to install, and Linde received payment of $161,426 from Bonneville for the acquisition of energy savings. This ECM would not have been implemented without the acquisition payment from Bonneville. The levelized cost of these energy savings to Bonneville will be 4.5 mills/kWh over the ECM's expected 15-year life, and the levelized cost to th.e region will be 5.9 mills/kWh.

  3. EVIDENCE FOR RADIOGENIC SULFUR-32 IN TYPE AB PRESOLAR SILICON CARBIDE GRAINS?

    SciTech Connect (OSTI)

    Fujiya, Wataru; Hoppe, Peter [Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, D-55128 Mainz (Germany)] [Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, D-55128 Mainz (Germany); Zinner, Ernst [Laboratory for Space Sciences and Physics Department, Campus Box 1105, Washington University, St. Louis, MO 63130 (United States)] [Laboratory for Space Sciences and Physics Department, Campus Box 1105, Washington University, St. Louis, MO 63130 (United States); Pignatari, Marco [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)] [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Herwig, Falk, E-mail: wataru.fujiya@mpic.de, E-mail: peter.hoppe@mpic.de, E-mail: ekz@wustl.edu, E-mail: mpignatari@gmail.com, E-mail: fherwig@uvic.ca [Department of Physics and Astronomy, University of Victoria, Canada, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)] [Department of Physics and Astronomy, University of Victoria, Canada, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)

    2013-10-20T23:59:59.000Z

    We report C, Si, and S isotope measurements on 34 presolar silicon carbide grains of Type AB, characterized by {sup 12}C/{sup 13}C < 10. Nitrogen, Mg-Al-, and Ca-Ti-isotopic compositions were measured on a subset of these grains. Three grains show large {sup 32}S excesses, a signature that has been previously observed for grains from supernovae (SNe). Enrichments in {sup 32}S may be due to contributions from the Si/S zone and the result of S molecule chemistry in still unmixed SN ejecta or due to incorporation of radioactive {sup 32}Si from C-rich explosive He shell ejecta. However, a SN origin remains unlikely for the three AB grains considered here, because of missing evidence for {sup 44}Ti, relatively low {sup 26}Al/{sup 27}Al ratios (a few times 10{sup –3}), and radiogenic {sup 32}S along with low {sup 12}C/{sup 13}C ratios. Instead, we show that born-again asymptotic giant branch (AGB) stars that have undergone a very-late thermal pulse (VLTP), known to have low {sup 12}C/{sup 13}C ratios and enhanced abundances of the light s-process elements, can produce {sup 32}Si, which makes such stars attractive sources for AB grains with {sup 32}S excesses. This lends support to the proposal that at least some AB grains originate from born-again AGB stars, although uncertainties in the born-again AGB star models and possible variations of initial S-isotopic compositions in the parent stars of AB grains make it difficult to draw a definitive conclusion.

  4. Carbide-Derived Carbons with Tunable Porosity Optimized for Hydrogen Storage

    SciTech Connect (OSTI)

    Fisher, John E.; Gogotsi, Yury; Yildirim, Taner

    2010-01-07T23:59:59.000Z

    On-board hydrogen storage is a key requirement for fuel cell-powered cars and trucks. Porous carbon-based materials can in principle adsorb more hydrogen per unit weight at room temperature than liquid hydrogen at -176 oC. Achieving this goal requires interconnected pores with very high internal surface area, and binding energies between hydrogen and carbon significantly enhanced relative to H2 on graphite. In this project a systematic study of carbide-derived carbons, a novel form of porous carbon, was carried out to discover a high-performance hydrogen sorption material to meet the goal. In the event we were unable to improve on the state of the art in terms of stored hydrogen per unit weight, having encountered the same fundamental limit of all porous carbons: the very weak interaction between H2 and the carbon surface. On the other hand we did discover several strategies to improve storage capacity on a volume basis, which should be applicable to other forms of porous carbon. Further discoveries with potentially broader impacts include • Proof that storage performance is not directly related to pore surface area, as had been previously claimed. Small pores (< 1.5 nm) are much more effective in storing hydrogen than larger ones, such that many materials with large total surface areas are sub-par performers. • Established that the distribution of pore sizes can be controlled during CDC synthesis, which opens the possibility of developing high performance materials within a common family while targeting widely disparate applications. Examples being actively pursued with other funding sources include methane storage, electrode materials for batteries and supercapacitors with record high specific capacitance, and perm-selective membranes which bind cytokines for control of infections and possibly hemodialysis filters.

  5. Assessment of Silicon Carbide Composites for Advanced Salt-Cooled Reactors

    SciTech Connect (OSTI)

    Katoh, Yutai [ORNL; Wilson, Dane F [ORNL; Forsberg, Charles W [ORNL

    2007-09-01T23:59:59.000Z

    The Advanced High-Temperature Reactor (AHTR) is a new reactor concept that uses a liquid fluoride salt coolant and a solid high-temperature fuel. Several alternative fuel types are being considered for this reactor. One set of fuel options is the use of pin-type fuel assemblies with silicon carbide (SiC) cladding. This report provides (1) an initial viability assessment of using SiC as fuel cladding and other in-core components of the AHTR, (2) the current status of SiC technology, and (3) recommendations on the path forward. Based on the analysis of requirements, continuous SiC fiber-reinforced, chemically vapor-infiltrated SiC matrix (CVI SiC/SiC) composites are recommended as the primary option for further study on AHTR fuel cladding among various industrially available forms of SiC. Critical feasibility issues for the SiC-based AHTR fuel cladding are identified to be (1) corrosion of SiC in the candidate liquid salts, (2) high dose neutron radiation effects, (3) static fatigue failure of SiC/SiC, (4) long-term radiation effects including irradiation creep and radiation-enhanced static fatigue, and (5) fabrication technology of hermetic wall and sealing end caps. Considering the results of the issues analysis and the prospects of ongoing SiC research and development in other nuclear programs, recommendations on the path forward is provided in the order or priority as: (1) thermodynamic analysis and experimental examination of SiC corrosion in the candidate liquid salts, (2) assessment of long-term mechanical integrity issues using prototypical component sections, and (3) assessment of high dose radiation effects relevant to the anticipated operating condition.

  6. Summary of the radiological assessment of the fuel cycle for a thorium-uranium carbide-fueled fast breeder reactor

    SciTech Connect (OSTI)

    Tennery, V.J.; Bomar, E.S.; Bond, W.D.; Meyer, H.R.; Morse, L.E.; Till, J.E.; Yalcintas, M.G.

    1980-01-01T23:59:59.000Z

    A large fraction of the potential fuel for nuclear power reactors employing fissionable materials exists as ores of thorium. In addition, certain characteristics of a fuel system based on breeding of the fissionable isotope {sup 233}U from thorium offer the possibility of a greater resistance to the diversion of fissionable material for the fabrication of nuclear weapons. This report consolidates into a single source the principal content of two previous reports which assess the radiological environmental impact of mining and milling of thorium ore and of the reprocessing and refabrication of spent FBR thorium-uranium carbide fuel.

  7. Effects of atmosphere on the tribological properties of a chromium carbide based coating for use to 760 C

    SciTech Connect (OSTI)

    Dellacorte, C.; Sliney, H.E.

    1988-04-01T23:59:59.000Z

    The effect of atmosphere on the tribological properties of a plasma-sprayed chromium carbide based self-lubricating coating is reported. The coating contains bonded chromium carbide as the wear resistant base stock to which the lubricants silver and barium fluoride/calcium fluoride eutectic are added. It has been denoted as NASA PS200. Potential applications for the PS200 coating are cylinder wall/piston ring couples Stirling engines and foil bearing journal lubrication. Friction and wear studies were performed in helium, hydrogen, and moist air at temperatures from 25 to 760 C. In general, the atmosphere had a significant effect on both the friction and the wear of the coating and counterface material. Specimens tested in hydrogen, a reducing environment, exhibited the best tribological properties. Friction and wear increased in helium and air but are still within acceptable limits for intended applications. A variety of X-ray analyses was performed on the test specimens in an effort to explain the results. The following conclusions are made: (1) As the test atmosphere becomes less reducing, the coating experiences a higher concentration level of chromic oxide at the sliding interface which increases both the friction and wear. (2) Beneficial silver transfer from the parent coating to the counter-face material is less effective in air than in helium or hydrogen. (3) There may be a direct relationship between chromic oxide level present at the sliding interface and the friction coefficient. 7 references.

  8. SILICON CARBIDE GRAINS OF TYPE C PROVIDE EVIDENCE FOR THE PRODUCTION OF THE UNSTABLE ISOTOPE {sup 32}Si IN SUPERNOVAE

    SciTech Connect (OSTI)

    Pignatari, M.; Rauscher, T.; Thielemann, F.-K. [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Zinner, E. [Laboratory for Space Sciences and the Physics Department, Washington University, St. Louis, MO 63130 (United States); Bertolli, M. G. [Theoretical Division (T-2), LANL, Los Alamos, NM 87545 (United States); Trappitsch, R. [Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637 (United States); Hoppe, P. [Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, D-55128 Mainz (Germany); Fryer, C. [Computational Physics and Methods (CCS-2), LANL, Los Alamos, NM 87545 (United States); Herwig, F. [Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada); Hirschi, R. [Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Timmes, F. X. [Joint Institute for Nuclear Astrophysics, Notre Dame, IN 46556 (United States)

    2013-07-01T23:59:59.000Z

    Carbon-rich grains are observed to condense in the ejecta of recent core-collapse supernovae (SNe) within a year after the explosion. Silicon carbide grains of type X are C-rich grains with isotopic signatures of explosive SN nucleosynthesis have been found in primitive meteorites. Much rarer silicon carbide grains of type C are a special sub-group of SiC grains from SNe. They show peculiar abundance signatures for Si and S, isotopically heavy Si, and isotopically light S, which appear to be in disagreement with model predictions. We propose that C grains are formed mostly from C-rich stellar material exposed to lower SN shock temperatures than the more common type X grains. In this scenario, extreme {sup 32}S enrichments observed in C grains may be explained by the presence of short-lived {sup 32}Si ({tau}{sub 1/2} = 153 yr) in the ejecta, produced by neutron capture processes starting from the stable Si isotopes. No mixing from deeper Si-rich material and/or fractionation of Si from S due to molecular chemistry is needed to explain the {sup 32}S enrichments. The abundance of {sup 32}Si in the grains can provide constraints on the neutron density reached during the SN explosion in the C-rich He shell material. The impact of the large uncertainty of the neutron capture cross sections in the {sup 32}Si region is discussed.

  9. Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

    SciTech Connect (OSTI)

    Way, J.; Wolden, Colin

    2013-09-30T23:59:59.000Z

    Colorado School of Mines (CSM) developed high temperature, hydrogen permeable membranes that contain no platinum group metals with the goal of separating hydrogen from gas mixtures representative of gasification of carbon feedstocks such as coal or biomass in order to meet DOE NETL 2015 hydrogen membrane performance targets. We employed a dual synthesis strategy centered on transition metal carbides. In the first approach, novel, high temperature, surface diffusion membranes based on nanoporous Mo{sub 2}C were fabricated on ceramic supports. These were produced in a two step process that consisted of molybdenum oxide deposition followed by thermal carburization. Our best Mo{sub 2}C surface diffusion membrane achieved a pure hydrogen flux of 367 SCFH/ft{sup 2} at a feed pressure of only 20 psig. The highest H{sub 2}/N{sub 2} selectivity obtained with this approach was 4.9. A transport model using “dusty gas” theory was derived to describe the hydrogen transport in the Mo{sub 2}C coated, surface diffusion membranes. The second class of membranes developed were dense metal foils of BCC metals such as vanadium coated with thin (< 60 nm) Mo{sub 2}C catalyst layers. We have fabricated a Mo{sub 2}C/V composite membrane that in pure gas testing delivered a H{sub 2} flux of 238 SCFH/ft{sup 2} at 600 °C and 100 psig, with no detectable He permeance. This exceeds the 2010 DOE Target flux. This flux is 2.8 times that of pure Pd at the same membrane thickness and test conditions and over 79% of the 2015 flux target. In mixed gas testing we achieved a permeate purity of ?99.99%, satisfying the permeate purity milestone, but the hydrogen permeance was low, ~0.2 SCFH/ft{sup 2}.psi. However, during testing of a Mo{sub 2}C coated Pd alloy membrane with DOE 1 feed gas mixture a hydrogen permeance of >2 SCFH/ft{sup 2}.psi was obtained which was stable during the entire test, meeting the permeance associated with the 2010 DOE target flux. Lastly, the Mo{sub 2}C/V composite membranes were shown to be stable for at least 168 hours = one week, including cycling at high temperature and alternating He/H{sub 2} exposure.

  10. Growth of Dome-Shaped Carbon Nanoislands on Ir(111): The Intermediate between Carbidic Clusters and Quasi-Free-Standing Graphene

    E-Print Network [OSTI]

    Alfè, Dario

    and Quasi-Free-Standing Graphene Paolo Lacovig,1 Monica Pozzo,2 Dario Alfe`,2 Paolo Vilmercati,3 of a long-range ordered graphene layer on Ir(111) assume a peculiar domelike shape. The understanding coupled carbidic carbon and a quasi-free-standing graphene layer, can provide information for a rational

  11. Theoretical Investigation of Hydrogen Adsorption and Dissociation on Iron and Iron Carbide Surfaces Using the ReaxFF Reactive Force Field Method

    SciTech Connect (OSTI)

    Zou, Chenyu; van Duin, Adri C.T.; Sorescu, Dan C.

    2012-06-01T23:59:59.000Z

    We have developed a ReaxFF reactive force field to describe hydrogen adsorption and dissociation on iron and iron carbide surfaces relevant for simulation of Fischer–Tropsch (FT) synthesis on iron catalysts. This force field enables large system (>>1000 atoms) simulations of hydrogen related reactions with iron. The ReaxFF force field parameters are trained against a substantial amount of structural and energetic data including the equations of state and heats of formation of iron and iron carbide related materials, as well as hydrogen interaction with iron surfaces and different phases of bulk iron. We have validated the accuracy and applicability of ReaxFF force field by carrying out molecular dynamics simulations of hydrogen adsorption, dissociation and recombination on iron and iron carbide surfaces. The barriers and reaction energies for molecular dissociation on these two types of surfaces have been compared and the effect of subsurface carbon on hydrogen interaction with iron surface is evaluated. We found that existence of carbon atoms at subsurface iron sites tends to increase the hydrogen dissociation energy barrier on the surface, and also makes the corresponding hydrogen dissociative state relatively more stable compared to that on bare iron. These properties of iron carbide will affect the dissociation rate of H{sub 2} and will retain more surface hydride species, thus influencing the dynamics of the FT synthesis process.

  12. Composition and method for brazing graphite to graphite

    DOE Patents [OSTI]

    Taylor, Albert J. (Ten Mile, TN); Dykes, Norman L. (Oak Ridge, TN)

    1984-01-01T23:59:59.000Z

    The present invention is directed to a brazing material for joining graphite structures that can be used at temperatures up to about 2800.degree. C. The brazing material formed of a paste-like composition of hafnium carbide and uranium oxide with a thermosetting resin. The uranium oxide is converted to uranium dicarbide during the brazing operation and then the hafnium carbide and uranium dicarbide form a liquid phase at a temperature about 2600.degree. C. with the uranium diffusing and vaporizing from the joint area as the temperature is increased to about 2800.degree. C. so as to provide a brazed joint consisting essentially of hafnium carbide. This brazing temperature for hafnium carbide is considerably less than the eutectic temperature of hafnium carbide of about 3150.degree. C. The brazing composition also incorporates the thermosetting resin so that during the brazing operation the graphite structures may be temporarily bonded together by thermosetting the resin so that machining of the structures to final dimensions may be completed prior to the completion of the brazing operation. The resulting brazed joint is chemically and thermally compatible with the graphite structures joined thereby and also provides a joint of sufficient integrity so as to at least correspond with the strength and other properties of the graphite.

  13. FUNCTIONALLY GRADED ALUMINA/MULLITE COATINGS FOR PROTECTION OF SILICON CARBIDE CERAMIC COMPONENTS FROM CORROSION

    SciTech Connect (OSTI)

    NONE

    1997-10-01T23:59:59.000Z

    The main objective of this research project is the formulation of processes that can be used to prepare compositionally graded alumina/mullite coatings for protection from corrosion of silicon carbide components (monolithic or composite) used or proposed to be used in coal utilization systems (e.g., combustion chamber liners, heat exchanger tubes, particulate removal filters, and turbine components) and other energy-related applications. Mullite will be employed as the inner (base) layer and the composition of the film will be continuously changed to a layer of pure alumina, which will function as the actual protective coating of the component. Chemical vapor deposition reactions of silica, alumina, and aluminosilicates (mullite) through hydrolysis of aluminum and silicon chlorides in the presence of CO{sub 2} and H{sub 2} will be employed to deposit compositionally graded films of mullite and alumina. Our studies will include the kinetic investigation of the silica, alumina, and aluminosilicate deposition processes, characterization of the composition, microstructure, surface morphology, and mechanical behavior of the prepared films, and modeling of the various deposition processes. During this six-month reporting period, we continued the work on the development and construction of the thermogravimetric chemical vapor deposition system that we intend to employ for studying the deposition of alumina, silica, and aluminosilicates (such as mullite) from mixtures of metal chlorides in H{sub 2} and CO{sub 2}. Specifically, we worked on the development of the tubular flow reactor that will be used for producing aluminum chloride for delivery to the chemical vapor deposition system and of the vapor and gas supply system. Various problems arising from condensation of aluminum chlorides in some sections of the supply line were resolved, and we expect to perform experiments using mixtures containing AlCl{sub 3} in the next reporting period. Preliminary experiments on the deposition of SiO{sub 2} from mixtures of methyltrichlorosilane (MTS) or tetrachlorosilane in H{sub 2} and CO{sub 2} were carried out, and the results showed that the deposition rates from MTS were much higher than those from SiCl{sub 4} and comparable to those reported in the literature for alumina deposition from AlC{sub 3}-H{sub 2}-CO{sub 2} mixtures of similar composition. It was thus decided to employ MTS as silicon source in our codeposition experiments, and a comprehensive investigation of thermodynamic equilibrium in the Al/Si/Cl/C/O/H system for compositions corresponding to MTS-AlCl{sub 3}-H{sub 2}-CO{sub 2} mixtures was conducted so as to identify the boundaries of the region of the space of operating parameters and conditions where preparation of functionally graded mullite/alumina coatings through CVD from metal chloride, CO{sub 2}, and H{sub 2} is feasible. The results showed that deposition of silica, alumina, mullite, and other aluminosilicates is feasible in a broad range of operating conditions from the equilibrated gas phase, but temperatures above 1148 K have to employed to obtain deposits of alumina and mullite if the solid phases are also at equilibrium with each other.

  14. FUNCTIONALLY GRADED ALUMINA/MULLITE COATINGS FOR PROTECTION OF SILICON CARBIDE CERAMIC COMPONENTS FROM CORROSION

    SciTech Connect (OSTI)

    NONE

    1998-03-01T23:59:59.000Z

    The main objective of this research project is the formulation of processes that can be used to prepare compositionally graded alumina/mullite coatings for protection from corrosion of silicon carbide components (monolithic or composite) used or proposed to be used in coal utilization systems (e.g., combustion chamber liners, heat exchanger tubes, particulate removal filters, and turbine components) and other energy-related applications. Mullite will be employed as the inner (base) layer and the composition of the film will be continuously changed to a layer of pure alumina, which will function as the actual protective coating of the component. Chemical vapor deposition reactions of silica, alumina, and aluminosilicates (mullite) through hydrolysis of aluminum and silicon chlorides in the presence of CO{sub 2} and H{sub 2} will be employed to deposit compositionally graded films of mullite and alumina. Our studies will include the kinetic investigation of the silica, alumina, and aluminosilicate deposition processes, characterization of the composition, microstructure, surface morphology, and mechanical behavior of the prepared films, and modeling of the various deposition processes. During this reporting period, the construction and development of the chemical vapor deposition system was completed, and experiments were conducted on the deposition of alumina, silica, and aluminosilicates (such as mullite) from mixtures of AlCl{sub 3} and CH{sub 3}SiCl{sub 3} in CO{sub 2} and H{sub 2}. Work was mainly done on the investigation of the effects of the reaction temperature on the deposition kinetics. It was found that the temperature had a positive effect on the single oxides deposition rates and the codeposition rate. The apparent activation energy values extracted from the deposition rate vs. temperature curves in the high temperature region were similar for the three deposition processes, having a value around 20 kcal/mol. The codeposition rates were higher, by a more than a factor of 2 in some cases, than the sum of the deposition rates of the two oxides in the independent experiments at the same operating conditions, and this result led to the conclusion that there should exist additional surface reaction steps in the codeposition process, that lead to solid formation and involve both silicon-containing and aluminum-containing species. The elemental analysis (EDXA) of films deposited from MTS-AlCl{sub 3}-CO{sub 2}- H2 mixtures showed that silicon oxide was the main component, and comparison of the deposition rates of SiO{sub 2} and Al{sub 2}O{sub 3} during codeposition with those seen in single species deposition experiments at the same conditions revealed that the codeposition process was characterized by a dramatic enhancement of the deposition of SiO{sub 2} and an equally dramatic reduction in the rate of Al{sub 2}O{sub 3} deposition. Since the enhanced codeposition rate was caused by increased silicon oxide deposition, it was concluded that the main deposition product of the additional surface reaction steps in codeposition must be silicon oxide. A comprehensive investigation of the effects of the other operating parameters on the kinetics of the codeposition process will be carried out in the next reporting period.

  15. Gas source molecular beam epitaxy of scandium nitride on silicon carbide and gallium nitride surfaces

    SciTech Connect (OSTI)

    King, Sean W., E-mail: sean.king@intel.com; Davis, Robert F. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Nemanich, Robert J. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-11-01T23:59:59.000Z

    Scandium nitride (ScN) is a group IIIB transition metal nitride semiconductor with numerous potential applications in electronic and optoelectronic devices due to close lattice matching with gallium nitride (GaN). However, prior investigations of ScN have focused primarily on heteroepitaxial growth on substrates with a high lattice mismatch of 7%–20%. In this study, the authors have investigated ammonia (NH{sub 3}) gas source molecular beam epitaxy (NH{sub 3}-GSMBE) of ScN on more closely lattice matched silicon carbide (SiC) and GaN surfaces (<3% mismatch). Based on a thermodynamic analysis of the ScN phase stability window, NH{sub 3}-GSMBE conditions of 10{sup ?5}–10{sup ?4} Torr NH{sub 3} and 800–1050?°C where selected for initial investigation. In-situ x-ray photoelectron spectroscopy (XPS) and ex-situ Rutherford backscattering measurements showed all ScN films grown using these conditions were stoichiometric. For ScN growth on 3C-SiC (111)-(?3?×??3)R30° carbon rich surfaces, the observed attenuation of the XPS Si 2p and C 1s substrate core levels with increasing ScN thickness indicated growth initiated in a layer-by-layer fashion. This was consistent with scanning electron microscopy (SEM) images of 100–200?nm thick films that revealed featureless surfaces. In contrast, ScN films grown on 3C-SiC (111)-(3?×?3) and 3C-SiC (100)-(3?×?2) silicon rich surfaces were found to exhibit extremely rough surfaces in SEM. ScN films grown on both 3C-SiC (111)-(?3?×??3)R30° and 2H-GaN (0001)-(1?×?1) epilayer surfaces exhibited hexagonal (1?×?1) low energy electron diffraction patterns indicative of (111) oriented ScN. X-ray diffraction ?-2? rocking curve scans for these same films showed a large full width half maximum of 0.29° (1047?arc sec) consistent with transmission electron microscopy images that revealed the films to be poly-crystalline with columnar grains oriented at ?15° to the [0001] direction of the 6H-SiC (0001) substrate. In-situ reflection electron energy loss spectroscopy measurements determined the band-gap for the NH{sub 3}-GSMBE ScN films to be 1.5?±?0.3 eV, and thermal probe measurements indicated all ScN films to be n-type. The four point probe sheet resistance of the ScN films was observed to increase with decreasing growth temperature and decreased with unintentional oxygen incorporation. Hg probe capacitance–voltage measurements indicated N{sub D}-N{sub A} decreased with decreasing growth temperature from 10{sup 19} to 10{sup 20}/cm{sup 3} for the lowest resistivity films to ?5?×?10{sup 16}/cm{sup 3} for the highest resistivity films. In-situ ultraviolet photoelectron spectroscopy measurements additionally showed the valence band maximum moving from 1.4 to 0.8 eV below the Fermi level with decreasing growth temperature consistent with the increased resistivity and reduction in carrier concentration. These results suggest that additional reductions in ScN carrier concentrations can be achieved via continued optimization of ScN growth conditions and selection of substrate orientation and surface termination.

  16. Optical properties of silicon carbide for astrophysical applications I. New laboratory infrared reflectance spectra and optical constants

    E-Print Network [OSTI]

    Pitman, K M; Corman, A B; Speck, A K

    2008-01-01T23:59:59.000Z

    Silicon Carbide (SiC) optical constants are fundamental inputs for radiative transfer models of astrophysical dust environments. However, previously published values contain errors and do not adequately represent the bulk physical properties of the cubic (beta) SiC polytype usually found around carbon stars. We provide new, uncompromised optical constants for beta- and alpha-SiC derived from single-crystal reflectance spectra and investigate quantitatively whether there is any difference between alpha- and beta-SiC that can be seen in infrared spectra and optical functions. Previous optical constants for SiC do not reflect the true bulk properties, and they are only valid for a narrow grain size range. The new optical constants presented here will allow narrow constraints to be placed on the grain size and shape distribution that dominate in astrophysical environments. In addition, our calculated absorption coefficients are much higher than laboratory measurements, which has an impact on the use of previous d...

  17. Effects of a modular two-step ozone-water and annealing process on silicon carbide graphene

    SciTech Connect (OSTI)

    Webb, Matthew J., E-mail: matthew.webb@cantab.net; Lundstedt, Anna; Grennberg, Helena [Department of Chemistry—BMC, Uppsala University, Box 576, SE-751 23 Uppsala (Sweden); Polley, Craig; Niu, Yuran; Zakharov, Alexei A.; Balasubramanian, Thiagarajan [MAX IV Laboratory, Lund University, 22100 Lund (Sweden); Dirscherl, Kai [DFM—Danish Fundamental Metrology, Matematiktorvet 307, DK-2800 Lyngby (Denmark); Burwell, Gregory; Guy, Owen J. [College of Engineering, Faraday Tower, Singleton Park, Swansea University, Swansea SA2 8PP (United Kingdom); Palmgren, Pål [VG Scienta Scientific AB, Box 15120, Vallongatan 1, SE-750 15 Uppsala (Sweden); Yakimova, Rositsa [Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping (Sweden)

    2014-08-25T23:59:59.000Z

    By combining ozone and water, the effect of exposing epitaxial graphene on silicon carbide to an aggressive wet-chemical process has been evaluated after high temperature annealing in ultra high vacuum. The decomposition of ozone in water produces a number of oxidizing species, however, despite long exposure times to the aqueous-ozone environment, no graphene oxide was observed after the two-step process. The systems were comprehensively characterized before and after processing using Raman spectroscopy, core level photoemission spectroscopy, and angle resolved photoemission spectroscopy together with low energy electron diffraction, low energy electron microscopy, and atomic force microscopy. In spite of the chemical potential of the aqueous-ozone reaction environment, the graphene domains were largely unaffected raising the prospect of employing such simple chemical and annealing protocols to clean or prepare epitaxial graphene surfaces.

  18. Testing erosion-resistant chromium carbide plasma coatings on the TVA Paradise Unit-2 intermediate pressure turbine

    SciTech Connect (OSTI)

    Karr, O.F.; Frank, R.L.; Gaston, D.E. Jr.; Bradford, T.L.

    1986-05-01T23:59:59.000Z

    Solid particle erosion (SPE) is caused by oxide particles in steam. Hard oxide particles exfoliate from the inside surfaces of boiler tubes and steam lines and are carried by the steam to the turbine where they impact and erode stationary and moving turbine parts (nozzles, moving blades, stationary blades, seal strips, and shrouds around the blades). The first stages of the high pressure (HP) and intermediate pressure (IP) turbines experience the greatest amount of SPE. Though many owners experience erosion in the first stages of both HP (main steam) and IP (reheat steam) turbines, TVA's principal erosion experience is in the IP or reheat steam turbines. This report is limited to the first few stages of IP turbines, referred to as ''first reheat stages.'' Hard chromium carbide plasma coatings have been developed. The coating was installed in Paradise Unit-2 IP turbine, 9th and 10th stages. Pretest inspection report is given.

  19. Behavior of microwave-heated silicon carbide particles at frequencies of 2.0–13.5?GHz

    SciTech Connect (OSTI)

    Sugawara, H.; Hayashi, M.; Ishihara, S. [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro, Tokyo 152-8552 (Japan); Kashimura, K., E-mail: kashimura@isc.chubu.ac.jp [Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501 (Japan); Mitani, T.; Shinohara, N. [Kyoto University, Gokasyo, Uji, Kyoto 611-0011 (Japan)

    2014-07-21T23:59:59.000Z

    Silicon carbide is a key material in microwave (MW) processing and is used widely as a thermal insulator and catalytic agent. In this study, we experimentally investigated the temperature dependence of the MW-absorption properties of SiC particles at frequencies of 2.0–13.5?GHz. We heated SiC particles of different sizes using MW radiation. The heating behaviors of the particles were then compared with their MW-absorption properties. The heating behavior of the particles was dependent on their radii; this result was in keeping with theoretical predictions. Furthermore, the ?-SiC particles exhibited anomalous behaviors when subjected to microwave heating at temperatures of 1100?°C and higher. These behaviors were attributable to the transformation of ?-SiC into the ?-phase. The underlying mechanism for this transformation is discussed on the basis of the results of X-ray diffraction analysis.

  20. Composition and method for brazing graphite to graphite

    DOE Patents [OSTI]

    Taylor, A.J.; Dykes, N.L.

    1982-08-10T23:59:59.000Z

    A brazing material is described for joining graphite structures that can be used up to 2800/sup 0/C. The brazing material is formed of a paste-like composition of hafnium carbide and uranium oxide with a thermosetting resin. The uranium oxide is converted to uranium dicarbide during the brazing operation and then the hafnium carbide and uranium dicarbide form a liquid phase at a temperature about 2600/sup 0/C with the uranium diffusing and vaporizing from the joint area as the temperature is increased to about 2800/sup 0/C so as to provide a brazed joint consisting essentially of hafnium carbide. The resulting brazed joint is chemically and thermally compatible with the graphite structures.

  1. Journal of Physics and Chemistry of Solids 67 (2006) 25122516 Crystal chemistry of layered carbide, Ti3(Si0.43Ge0.57)C2

    E-Print Network [OSTI]

    Downs, Robert T.

    2006-01-01T23:59:59.000Z

    , Ti3(Si0.43Ge0.57)C2 Hexiong Yanga,Ã, B. Manouna , R.T. Downsb , A. Gangulyc , M.W. Barsoumc a Center structure of a layered ternary carbide, Ti3(Si0.43Ge0.57)C2, was studied with single-crystal X.0823(1) A° , c ¼ 17.7702(6) A° , and V ¼ 146.21(1) A° 3 . The Si and Ge atoms in the structure occupy

  2. An application of Ti-K X-ray absorption edges and fine structures to the study of substoichiometric titanium carbide TiC1-x

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    of substoichiometric titanium carbide TiC1-x V. Moisy-Maurice and C. H. de Novion C.E.A./IRDI/DMECN/DTech, Laboratoire-ray absorption coefficient were made around and up to 1000 eV above the titanium K-edge of TiC1-x samples (0 of titanium deduced from the edge-shift decreases, (ii) the bottom of the titanium 4p bands (situated at 10

  3. Review of corrosion behavior of ceramic heat exchanger materals: Corrosion characteristics of silicon carbide and silicon nitride. Final report, September 11, 1992--March 11, 1993

    SciTech Connect (OSTI)

    Munro, R.G.; Dapkunas, S.J.

    1993-09-01T23:59:59.000Z

    The present work is a review of the substantial effort that has been made to measure and understand the effects of corrosion with respect to the properties, performance, and durability of various forms of silicon carbide and silicon nitride. The review encompasses corrosion in diverse environments, usually at temperatures of 1000C or higher. The environments include dry and moist oxygen, mixtures of hot gaseous vapors, molten salts, molten metals, and complex environments pertaining to coal ashes and slags.

  4. Synthesis of Nanostructured Carbides of Titanium and Vanadium from Metal Oxides and Ferroalloys Through High-energy Mechanical Milling and Heat Treatment

    SciTech Connect (OSTI)

    Basu, P.; Jian, P. F.; Seong, K. Y.; Seng, G. S.; Hussain, Z.; Aziz, A. [School of Materials and Minerals Resources Engineering, Universiti Sains Malaysia (USM), Engineering Campus, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Masrom, A. K. [Advanced Materials Research Centre (AMREC), SIRIM Bhd, Kulim Hi-Tech Park, Kulim 09000 (Malaysia)

    2010-03-11T23:59:59.000Z

    Carbides of Ti and V have been synthesized directly from their oxides and ferroalloys through mechanical milling and heat treatment. The powder mixtures are milled in a planetary ball mill from 15-80 hours and subsequently heat treated at 1000-1300 deg. C for TiO{sub 2}-C mixtures, at 500-550 deg. C for V{sub 2}O{sub 5}-C mixtures and at 600-1000 deg. C for (Fe-V)-C mixtures. The milled and heat treated powders are characterized by SEM, EDAX, XRD, and BET techniques. Nanostructured TiC has been successfully synthesized under suitable processing conditions. However, carbides of vanadium is unidentified even though possibilities of V{sub 2}O{sub 5}-C reaction are indicated with an extent of induced amorphism in the powder mixture. Density, specific surface area and particle size of the milled and heat treated mixtures are correlated with heat treatment temperatures. Similar attempts are also made to synthesize vanadium carbides from industrial grade Fe-V.

  5. Composites comprising silicon carbide fibers dispersed in magnesia-aluminate matrix and fabrication thereof and of other composites by sinter forging

    DOE Patents [OSTI]

    Panda, Prakash C. (Ithaca, NY); Seydel, Edgar R. (Ithaca, NY); Raj, Rishi (Ithaca, NY)

    1989-10-03T23:59:59.000Z

    A novel ceramic-ceramic composite of a uniform dispersion of silicon carbide fibers in a matrix of MgO.multidot.nAl.sub.2 O.sub.3 wherein n ranges from about 1 to about 4.5, said composite comprising by volume from 1 to 50% silicon carbide fibers and from 99 to 50% MgO.multidot.nAl.sub.2 O.sub.3. The composite is readily fabricated by forming a powder comprising a uniform dispersion of silicon carbide fibers in poorly crystalline phase comprising MgO and Al.sub.2 O.sub.3 in a mole ratio of n and either (a) hot pressing or preferably (b) cold pressing to form a preform and then forging utilizing a temperature in the range of 1100.degree. C. to 1900.degree. C. and a strain rate ranging from about 10.sup.-5 seconds .sup.-1 to about 1 seconds .sup.-1 so that surfaces cracks do not appear to obtain a shear deformation greater than 30%.

  6. Active wear and failure mechanisms of TiN-coated high speed steel and TiN-coated cemented carbide tools when machining powder metallurgically made stainless steels

    SciTech Connect (OSTI)

    Jiang, L.; Haenninen, H.; Paro, J.; Kauppinen, V. [Helsinki Univ. of Technology, Espoo (Finland)

    1996-09-01T23:59:59.000Z

    In this study, active wear and failure mechanisms of both TiN-coated high speed steel and TiN-coated cemented carbide tools when machining stainless steels made by powder metallurgy in low and high cutting speed ranges, respectively, have been investigated. Abrasive wear mechanisms, fatigue-induced failure, and adhesive and diffusion wear mechanisms mainly affected the tool life of TiN-coated high speed steel tools at cutting speeds below 35 m/min, between 35 and 45 m/min, and over 45 m/min, respectively. Additionally, fatigue-induced failure was active at cutting speeds over 45 m/min in the low cutting speed range when machining powder metallurgically made duplex stainless steel 2205 and austenitic stainless steel 316L. In the high cutting speed range, from 100 to 250 m/min, fatigue-induced failure together with diffusion wear mechanism, affected the tool life of TiN-coated cemented carbide tools when machining both 316L and 2205 stainless steels. It was noticed that the tool life of TiN-coated high speed steel tools used in the low cutting speed range when machining 2205 steel was longer than that when machining 316L steel, whereas the tool life of TiN-coated cemented carbide tools used in the high cutting speed range when machining 316L steel was longer than that when machining 2205 steel.

  7. Tungsten carbide/porous carbon composite as superior support for platinum catalyst toward methanol electro-oxidation

    SciTech Connect (OSTI)

    Jiang, Liming [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Fu, Honggang, E-mail: fuhg@vip.sina.com [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Key Laboratory of Functional Inorganic Material Chemistry, Heilongjiang University, Harbin 150080 (China); Wang, Lei; Mu, Guang; Jiang, Baojiang; Zhou, Wei; Wang, Ruihong [Key Laboratory of Functional Inorganic Material Chemistry, Heilongjiang University, Harbin 150080 (China)

    2014-01-01T23:59:59.000Z

    Graphical abstract: The WC nanoparticles are well dispersed in the carbon matrix. The size of WC nanoparticles is about 30 nm. It can be concluded that tungsten carbide and carbon composite was successfully prepared by the present synthesis conditions. - Highlights: • The WC/PC composite with high specific surface area was prepared by a simple way. • The Pt/WC/PC catalyst has superior performance toward methanol electro-oxidation. • The current density for methanol electro-oxidation is as high as 595.93 A g{sup ?1} Pt. • The Pt/WC/PC catalyst shows better durability and stronger CO electro-oxidation. • The performance of Pt/WC/PC is superior to the commercial Pt/C (JM) catalyst. - Abstract: Tungsten carbide/porous carbon (WC/PC) composites have been successfully synthesized through a surfactant assisted evaporation-induced-assembly method, followed by a thermal treatment process. In particular, WC/PC-35-1000 composite with tungsten content of 35% synthesized at the carbonized temperature of 1000 °C, exhibited a specific surface area (S{sub BET}) of 457.92 m{sup 2} g{sup ?1}. After loading Pt nanoparticles (NPs), the obtained Pt/WC/PC-35-1000 catalyst exhibits the highest unit mass electroactivity (595.93 A g{sup ?1} Pt) toward methanol electro-oxidation, which is about 2.6 times as that of the commercial Pt/C (JM) catalyst. Furthermore, the Pt/WC/PC-35-1000 catalyst displays much stronger resistance to CO poisoning and better durability toward methanol electrooxidation compared with the commercial Pt/C (JM) catalyst. The high electrocatalytic activity, strong poison-resistivity and good stability of Pt/WC/PC-35-1000 catalyst are attributed to the porous structures and high specific surface area of WC/PC support could facilitate the rapid mass transportation. Moreover, synergistic effect between WC and Pt NPs is favorable to the higher catalytic performance.

  8. Optical properties of silicon carbide for astrophysical applications I. New laboratory infrared reflectance spectra and optical constants

    E-Print Network [OSTI]

    K. M. Pitman; A. M. Hofmeister; A. B. Corman; A. K. Speck

    2008-03-10T23:59:59.000Z

    Silicon Carbide (SiC) optical constants are fundamental inputs for radiative transfer models of astrophysical dust environments. However, previously published values contain errors and do not adequately represent the bulk physical properties of the cubic (beta) SiC polytype usually found around carbon stars. We provide new, uncompromised optical constants for beta- and alpha-SiC derived from single-crystal reflectance spectra and investigate quantitatively whether there is any difference between alpha- and beta-SiC that can be seen in infrared spectra and optical functions. Previous optical constants for SiC do not reflect the true bulk properties, and they are only valid for a narrow grain size range. The new optical constants presented here will allow narrow constraints to be placed on the grain size and shape distribution that dominate in astrophysical environments. In addition, our calculated absorption coefficients are much higher than laboratory measurements, which has an impact on the use of previous data to constrain abundances of these dust grains.

  9. Transition metal carbides, nitrides and borides, and their oxygen containing analogs useful as water gas shift catalysts

    DOE Patents [OSTI]

    Thompson, Levi T.; Patt, Jeremy; Moon, Dong Ju; Phillips, Cory

    2003-09-23T23:59:59.000Z

    Mono- and bimetallic transition metal carbides, nitrides and borides, and their oxygen containing analogs (e.g. oxycarbides) for use as water gas shift catalysts are described. In a preferred embodiment, the catalysts have the general formula of M1.sub.A M2.sub.B Z.sub.C O.sub.D, wherein M1 is selected from the group consisting of Mo, W, and combinations thereof; M2 is selected from the group consisting of Fe, Ni, Cu, Co, and combinations thereof; Z is selected from the group consisting of carbon, nitrogen, boron, and combinations thereof; A is an integer; B is 0 or an integer greater than 0; C is an integer; O is oxygen; and D is 0 or an integer greater than 0. The catalysts exhibit good reactivity, stability, and sulfur tolerance, as compared to conventional water shift gas catalysts. These catalysts hold promise for use in conjunction with proton exchange membrane fuel cell powered systems.

  10. Superconducting and structural properties of {delta}-MoC{sub 0.681} cubic molybdenum carbide phase

    SciTech Connect (OSTI)

    Sathish, C.I. [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan) [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Guo, Yanfeng, E-mail: GUO.Yanfeng@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)] [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Wang, Xia [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan) [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Tsujimoto, Yoshihiro [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)] [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Li, Jun [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan) [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Zhang, Shoubao [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)] [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Matsushita, Yoshitaka [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan)] [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan); Shi, Youguo; Tian, Huanfang; Yang, Huaixin; Li, Jianqi [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)] [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yamaura, Kazunari, E-mail: YAMAURA.Kazunari@nims.go.jp [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan) [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2012-12-15T23:59:59.000Z

    The superconducting and lattice properties of {delta}-MoC{sub 0.681} were studied by electromagnetic measurements, synchrotron X-ray diffraction, neutron diffraction, and electron diffraction. The superconducting properties (T{sub c}=12 K) of {delta}-MoC{sub 0.681} were well characterized by a weak coupling model. The carbon vacancies present in the host cubic structure were found to be robust, although the material was synthesized from stoichiometric carbon and Mo powder under a high-pressure of 6 GPa. A thermodynamically-stable structure with ordered vacancies did not account for the robust features of {delta}-MoC{sub 0.681} since the vacancies are unlikely to be ordered in long range in the host structure. A model based on inherent phonon instability theoretically predicted for a stoichiometric MoC phase might be responsible for the robust features of {delta}-MoC{sub 0.681}. - Graphical Abstract: The cubic molybdenum carbide shows an excellent superconductivity with robust carbon vacancies. Inherent phonon instability theoretically predicted for a stoichiometric MoC phase might be responsible for the vacancies rather than a thermodynamically-stable structure with vacancies ordering. Highlights: Black-Right-Pointing-Pointer The 12 K superconductivity is well characterized by a weakly coupling model. Black-Right-Pointing-Pointer Carbon vacancies are robust and disordered in the cubic host structure. Black-Right-Pointing-Pointer Inherent phonon instability might be responsible for the robust carbon vacancies in {delta}-MoC{sub 0.681}.

  11. The Effects of Damage on Hydrogen-Implant-Induced Thin-Film Separation from Bulk Silicon Carbide

    SciTech Connect (OSTI)

    Gregory, R.B.; Holland, O.W.; Thomas, D.K.; Wetteroth, T.A.; Wilson, S.R.

    1999-04-05T23:59:59.000Z

    Exfoliation of Sic by hydrogen implantation and subsequent annealing forms the basis for a thin-film separation process which, when combined with hydrophilic wafer bonding, can be exploited to produce silicon-carbide-on-insulator, SiCOI. Sic thin films produced by this process exhibit unacceptably high resistivity because defects generated by the implant neutralize electrical carriers. Separation occurs because of chemical interaction of hydrogen with dangling bonds within microvoids created by the implant, and physical stresses due to gas-pressure effects during post-implant anneal. Experimental results show that exfoliation of Sic is dependent upon the concentration of implanted hydrogen, but the damage generated by the implant approaches a point when exfoliation is, in fact, retarded. This is attributed to excessive damage at the projected range of the implant which inhibits physical processes of implant-induced cleaving. Damage is controlled independently of hydrogen dosage by elevating the temperature of the SiC during implant in order to promote dynamic annealing. The resulting decrease in damage is thought to promote growth of micro-cracks which form a continuous cleave. Channeled H{sup +} implantation enhances the cleaving process while simultaneously minimizing residual damage within the separated film. It is shown that high-temperature irradiation and channeling each reduces the hydrogen fluence required to affect separation of a thin film and results in a lower concentration of defects. This increases the potential for producing SiC01 which is sufficiently free of defects and, thus, more easily electrically activated.

  12. Powerful, Efficient Electric Vehicle Chargers: Low-Cost, Highly-Integrated Silicon Carbide (SiC) Multichip Power Modules (MCPMs) for Plug-In Hybrid Electric

    SciTech Connect (OSTI)

    None

    2010-09-14T23:59:59.000Z

    ADEPT Project: Currently, charging the battery of an electric vehicle (EV) is a time-consuming process because chargers can only draw about as much power from the grid as a hair dryer. APEI is developing an EV charger that can draw as much power as a clothes dryer, which would drastically speed up charging time. APEI's charger uses silicon carbide (SiC)-based power transistors. These transistors control the electrical energy flowing through the charger's circuits more effectively and efficiently than traditional transistors made of straight silicon. The SiC-based transistors also require less cooling, enabling APEI to create EV chargers that are 10 times smaller than existing chargers.

  13. Wear Mechanism of Chemical Vapor Deposition (CVD) Carbide Insert in Orthogonal Cutting Ti-6Al-4V ELI at High Cutting Speed

    SciTech Connect (OSTI)

    Gusri, A. I.; Che Hassan, C. H.; Jaharah, A. G. [Mechanical and Material Engineering Department, Universiti Kebangsaan Malaysia, Bangi 43600 (Malaysia)

    2011-01-17T23:59:59.000Z

    The performance of Chemical Vapor Deposition (CVD) carbide insert with ISO designation of CCMT 12 04 04 LF, when turning titanium alloys was investigated. There were four layers of coating materials for this insert i.e.TiN-Al2O3-TiCN-TiN. The insert performance was evaluated based on the insert's edge resistant towards the machining parameters used at high cutting speed range of machining Ti-6Al-4V ELI. Detailed study on the wear mechanism at the cutting edge of CVD carbide tools was carried out at cutting speed of 55-95 m/min, feed rate of 0.15-0.35 mm/rev and depth of cut of 0.10-0.20 mm. Wear mechanisms such as abrasive and adhesive were observed on the flank face. Crater wear due to diffusion was also observed on the rake race. The abrasive wear occurred more at nose radius and the fracture on tool were found at the feed rate of 0.35 mm/rev and the depth of cut of 0.20 mm. The adhesion wear takes place after the removal of the coating or coating delaminating. Therefore, adhesion or welding of titanium alloy onto the flank and rake faces demonstrates a strong bond at the workpiece-tool interface.

  14. Neutron diffraction study of the formation of ordered antiphase domains in cubic titanium carbide TiC{sub 0.60}

    SciTech Connect (OSTI)

    Khidirov, I., E-mail: khidirov@inp.uz; Parpiev, A. S. [Academy of Sciences of Uzbekistan, Institute of Nuclear Physics (Uzbekistan)

    2013-05-15T23:59:59.000Z

    A series of superstructural reflections (described within the sp. gr. Fd3m) are found to be split into three symmetric parts in the neutron powder diffraction pattern of titanium carbide TiC{sub 0.60} annealed at a temperature of 600 Degree-Sign C. No splitting of superstructural reflections is observed in the neutron diffraction pattern of TiC{sub 0.60} annealed at relatively high temperatures (780 Degree-Sign C). This phenomenon can be explained by that fact that the ordering of carbon atoms at relatively high temperatures (780 Degree-Sign C) is accompanied by the formation of randomly oriented rather large antiphase domains (APDs) (450 A). At relatively low temperatures (600 Degree-Sign C), stacking faults arise in the arrangement of partially ordered carbon atoms. In this case, relatively small ordered APDs (290 A) are formed, along with disordered ones.

  15. Elastic properties, sp{sup 3} fraction, and Raman scattering in low and high pressure synthesized diamond-like boron rich carbides

    SciTech Connect (OSTI)

    Zinin, Pavel V.; Burgess, Katherine; Jia, Ruth; Sharma, Shiv; Ming, Li-Chung [Hawaii Institute of Geophysics and Planetology, University of Hawaii, Honolulu, Hawaii 96822 (United States); Liu, Yongsheng [Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an Shanxi (China); Ciston, Jim [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Hong, Shiming [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, Sichuan (China)

    2014-10-07T23:59:59.000Z

    Dense BC{sub x} phases with high boron concentration are predicted to be metastable, superhard, and conductors or superconductors depending on boron concentration. However, up to this point, diamond-like boron rich carbides BC{sub x} (dl-BC{sub x}) phases have been thought obtainable only through high pressure and high temperature treatment, necessitating small specimen volume. Here, we use electron energy loss spectroscopy combined with transmission electron microscopy, Raman spectroscopy, surface Brillouin scattering, laser ultrasonics (LU) technique, and analysis of elastic properties to demonstrate that low pressure synthesis (chemical vapor deposition) of BC{sub x} phases may also lead to the creation of diamond-like boron rich carbides. The elastic properties of the dl-BC{sub x} phases depend on the carbon sp{sup 2} versus sp{sup 3} content, which decreases with increasing boron concentration, while the boron bonds determine the shape of the Raman spectra of the dl-BC{sub x} after high pressure-high temperature treatment. Using the estimation of the density value based on the sp{sup 3} fraction, the shear modulus ? of dl-BC{sub 4}, containing 10% carbon atoms with sp{sup 3} bonds, and dl-B{sub 3}C{sub 2}, containing 38% carbon atoms with sp{sup 3} bonds, were found to be ??=?19.3?GPa and ??=?170?GPa, respectively. The presented experimental data also imply that boron atoms lead to a creation of sp{sup 3} bonds during the deposition processes.

  16. Analytical and experimental evaluation of joining silicon nitride to metal and silicon carbide to metal for advanced heat engine applications. Final report

    SciTech Connect (OSTI)

    Kang, S.; Selverian, J.H.; O`Neil, D.; Kim, H. [GTE Labs., Inc., Waltham, MA (US); Kim, K. [Brown Univ., Providence, RI (US). Div. of Engineering

    1993-05-01T23:59:59.000Z

    This report summarizes the results of Phase 2 of Analytical and Experimental Evaluation of Joining Silicon Nitride to Metal and Silicon Carbide to Metal for Advanced Heat Engine Applications. A general methodology was developed to optimize the joint geometry and material systems for 650{degrees}C applications. Failure criteria were derived to predict the fracture of the braze and ceramic. Extensive finite element analyses (FEA) were performed to examine various joint geometries and to evaluate the affect of different interlayers on the residual stress state. Also, material systems composed of coating materials, interlayers, and braze alloys were developed for the program based on the chemical stability and strength of the joints during processing, and service. The FEA results were compared with experiments using two methods: (1) an idealized strength relationship of the ceramic, and (2) a probabilistic analysis of the ceramic strength (NASA CARES). The results showed that the measured strength of the joint reached 30--80% of the strength predicted by FEA. Also, potential high-temperature braze alloys were developed and evaluated for the high-temperature application of ceramic-metal joints. 38 tabs, 29 figs, 20 refs.

  17. Deposition of mullite and mullite-like coatings on silicon carbide by dual-source metal plasma immersion. Topical report, October 1995--September 1996

    SciTech Connect (OSTI)

    Brown, I.G.; Monteiro, O.R. [Lawrence Berkeley National Lab., CA (United States)

    1997-04-01T23:59:59.000Z

    Mullite and mullite-like coatings on silicon carbide have been produced by a Metal Plasma Immersion Ion Implantation and Deposition (Mepiiid) technique based on two cathodic vacuum arc sources and concurrent pulse biasing of the substrate in an oxygen atmosphere. The deposition was carried out at oxygen partial pressures of between 0.66 and 3.33 Pa. The Al:Si ratio in the films varied from 1:1 to 8:1 and was controlled by varying the pulse duration of the separate plasma guns. High bias voltage was used early in the deposition process in order to produce atomic mixing at the film-substrate interface, while lower bias voltage was used later in the deposition; low ion energy allows control of the physical properties of the film as well as faster deposition rates. The as-deposited films were amorphous, and crystalline mullite was formed by subsequent annealing at 1,100 C for 2 hours in air. Strong adhesion between the mullite and the SiC was achieved, in some cases exceeding the 70 MPa instrumental limit of the pull-tester.

  18. Optical constants of silicon carbide for astrophysical applications. II. Extending optical functions from IR to UV using single-crystal absorption spectra

    E-Print Network [OSTI]

    Hofmeister, A M; Goncharov, A F; Speck, A K

    2009-01-01T23:59:59.000Z

    Laboratory measurements of unpolarized and polarized absorption spectra of various samples and crystal stuctures of silicon carbide (SiC) are presented from 1200--35,000 cm$^{-1}$ ($\\lambda \\sim$ 8--0.28 $\\mu$m) and used to improve the accuracy of optical functions ($n$ and $k$) from the infrared (IR) to the ultraviolet (UV). Comparison with previous $\\lambda \\sim$ 6--20 $\\mu$m thin-film spectra constrains the thickness of the films and verifies that recent IR reflectivity data provide correct values for $k$ in the IR region. We extract $n$ and $k$ needed for radiative transfer models using a new ``difference method'', which utilizes transmission spectra measured from two SiC single-crystals with different thicknesses. This method is ideal for near-IR to visible regions where absorbance and reflectance are low and can be applied to any material. Comparing our results with previous UV measurements of SiC, we distinguish between chemical and structural effects at high frequency. We find that for all spectral re...

  19. Standard test methods for chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade aluminum oxide and aluminum oxide-boron carbide composite pellets

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    1994-01-01T23:59:59.000Z

    1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade aluminum oxide and aluminum oxide-boron carbide composite pellets to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Sections Boron by Titrimetry 7 to 13 Separation of Boron for Mass Spectrometry 14 to 19 Isotopic Composition by Mass Spectrometry 20 to 23 Separation of Halides by Pyrohydrolysis 24 to 27 Fluoride by Ion-Selective Electrode 28 to 30 Chloride, Bromide, and Iodide by Amperometric Microtitrimetry 31 to 33 Trace Elements by Emission Spectroscopy 34 to 46 1.3 The values stated in SI units are to be regarded as the standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (F...

  20. OPTICAL CONSTANTS OF SILICON CARBIDE FOR ASTROPHYSICAL APPLICATIONS. II. EXTENDING OPTICAL FUNCTIONS FROM INFRARED TO ULTRAVIOLET USING SINGLE-CRYSTAL ABSORPTION SPECTRA

    SciTech Connect (OSTI)

    Hofmeister, A. M.; Pitman, K. M. [Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130 (United States); Goncharov, A. F. [Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015 (United States); Speck, A. K. [Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO 65211 (United States)], E-mail: hofmeist@levee.wustl.edu

    2009-05-10T23:59:59.000Z

    Laboratory measurements of unpolarized and polarized absorption spectra of various samples and crystal structures of silicon carbide (SiC) are presented from 1200-35000 cm{sup -1} ({lambda} {approx} 8-0.28 {mu}m) and used to improve the accuracy of optical functions (n and k) from the infrared (IR) to the ultraviolet (UV). Comparison with previous {lambda} {approx} 6-20 {mu}m thin-film spectra constrains the thickness of the films and verifies that recent IR reflectivity data provide correct values for k in the IR region. We extract n and k needed for radiative transfer models using a new 'difference method', which utilizes transmission spectra measured from two SiC single-crystals with different thicknesses. This method is ideal for near-IR to visible regions where absorbance and reflectance are low and can be applied to any material. Comparing our results with previous UV measurements of SiC, we distinguish between chemical and structural effects at high frequency. We find that for all spectral regions, 3C ({beta}-SiC) and the E-vector perpendicular c-vector polarization of 6H (a type of {alpha}-SiC) have almost identical optical functions that can be substituted for each other in modeling astronomical environments. Optical functions for E-vector || c-vector of 6H SiC have peaks shifted to lower frequency, permitting identification of this structure below {lambda} {approx} 4 {mu}m. The onset of strong UV absorption for pure SiC occurs near 0.2 {mu}m, but the presence of impurities redshifts the rise to 0.33 {mu}m. Optical functions are similarly impacted. Such large differences in spectral characteristics due to structural and chemical effects should be observable and provide a means to distinguish chemical variation of SiC dust in space.

  1. A methodology to identify and quantify mobility-reducing defects in 4H-silicon carbide power metal-oxide-semiconductor field-effect transistors

    SciTech Connect (OSTI)

    Ettisserry, D. P., E-mail: deva@umd.edu; Goldsman, N. [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States); Lelis, A. [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States)

    2014-03-14T23:59:59.000Z

    In this paper, we present a methodology for the identification and quantification of defects responsible for low channel mobility in 4H-Silicon Carbide (SiC) power metal-oxide-semiconductor field-effect transistors (MOSFETs). To achieve this, we use an algorithm based on 2D-device simulations of a power MOSFET, density functional simulations, and measurement data. Using physical modeling of carrier mobility and interface traps, we reproduce the experimental I-V characteristics of a 4H-SiC doubly implanted MOSFET through drift-diffusion simulation. We extract the position of Fermi level and the occupied trap density as a function of applied bias and temperature. Using these inputs, our algorithm estimates the number of possible trap types, their energy levels, and concentrations at 4H-SiC/SiO{sub 2} interface. Subsequently, we use density functional theory (DFT)-based ab initio simulations to identify the atomic make-up of defects causing these trap levels. We study silicon vacancy and carbon di-interstitial defects in the SiC side of the interface. Our algorithm indicates that the D{sub it} spectrum near the conduction band edge (3.25?eV) is composed of three trap types located at 2.8–2.85?eV, 3.05?eV, and 3.1–3.2?eV, and also calculates their densities. Based on DFT simulations, this work attributes the trap levels very close to the conduction band edge to the C di-interstitial defect.

  2. Status of cross-section data for gas production from vanadium and {sup 26}AL from silicon carbide in a D-T fusion reactor.

    SciTech Connect (OSTI)

    Gomes, I. C.

    1998-08-11T23:59:59.000Z

    Current designs of fusion-reactor systems seek to use radiation-resistant, low-activation materials that support long service lifetimes and minimize radioactive-waste problems after decommissioning. Reliable assessment of fusion materials performance requires accurate neutron-reaction cross sections and radioactive-decay constants. The problem areas usually involve cross sections since decay parameters tend to be better known. The present study was motivated by two specific questions: (i) Why are the {sup 51}V(n,np){sup 50}Ti cross section values in the ENDF/B-VI library so large (a gas production issue)? (ii) How well known are the cross sections associated with producing 7.4 x 10{sup 5} y {sup 26}Al in silicon carbide by the process {sup 28}Si(n,np+d){sup 27} Al(n,2n){sup 26}Al (a long-lived radioactivity issue)? The energy range 14-15 MeV of the D-T fusion neutrons is emphasized. Cross-section error bars are needed so that uncertainties in the gas and radioactivity generated over the lifetime of a reactor can be estimated. We address this issue by comparing values obtained from prominent evaluated cross-section libraries. Small differences between independent evaluations indicate that a physical quantity is well known while the opposite signals a problem. Hydrogen from {sup 51}V(n,p){sup 51}Ti and helium from {sup 51}V(n,{alpha}){sup 48}Sc are also important sources of gas in vanadium, so they too were examined. We conclude that {sup 51}V(n,p){sup 51}Ti is adequately known but {sup 51}V(n,np+d){sup 50}Ti is not. The status for helium generation data is quite good. Due to recent experimental work, {sup 27}Al(n,2n){sup 26}Al seems to be fairly well known. However, the situation for {sup 28}Si(n,np+d){sup 27}Al remains unsatisfactory.

  3. Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites

    SciTech Connect (OSTI)

    Newsome G, Snead L, Hinoki T, Katoh Y, Peters D

    2007-03-26T23:59:59.000Z

    The effects of fast neutron irradiation on SiC and SiC composites have been studied. The materials used were chemical vapor deposition (CVD) SiC and SiC/SiC composites reinforced with either Hi-Nicalon{trademark} Type-S, Hi-Nicalon{trademark} or Sylramic{trademark} fibers fabricated by chemical vapor infiltration. Statistically significant numbers of flexural samples were irradiated up to 4.6 x 10{sup 25} n/m{sup 2} (E>0.1 MeV) at 300, 500 and 800 C in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Dimensions and weights of the flexural bars were measured before and after the neutron irradiation. Mechanical properties were evaluated by four point flexural testing. Volume increase was seen for all bend bars following neutron irradiation. Magnitude of swelling depended on irradiation temperature and material, while it was nearly independent of irradiation fluence over the fluence range studied. Flexural strength of CVD SiC increased following irradiation depending on irradiation temperature. Over the temperature range studied, no significant degradation in mechanical properties was seen for composites fabricated with Hi-Nicalon{trademark} Type-S, while composites reinforced with Hi-Nicalon{trademark} or Sylramic fibers showed significant degradation. The effects of irradiation on the Weibull failure statistics are also presented suggesting a reduction in the Weibull modulus upon irradiation. The cause of this potential reduction is not known.

  4. Silicon Carbide and Silicon Carbide Composites for Fusion Reactor Applications

    SciTech Connect (OSTI)

    Hinoki, Tatsuya [Kyoto University, Japan] [Kyoto University, Japan; Hasegawa, Akira [Tohoku University, Japan] [Tohoku University, Japan; Katoh, Yutai [ORNL] [ORNL; Snead, Lance Lewis [ORNL] [ORNL; Jung, H.C. [Kyoto University, Japan] [Kyoto University, Japan; Katsui, Hirokazu [Tohoku University, Japan] [Tohoku University, Japan; Kondo, Sosuke [ORNL] [ORNL; Zhong, Z. H. [Kyoto University, Japan] [Kyoto University, Japan; Park, Y. H. [Kyoto University, Japan] [Kyoto University, Japan; Shih, Chunghao [ORNL] [ORNL; Ozawa, Kazumi [ORNL] [ORNL; Parish, Chad M [ORNL] [ORNL; Meisner, Roberta Ann [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    This paper reviews recent achievements as to "nuclear-grade" SiC composites in particular for materials-system integration. SiC composite component development are reviewed including VHTR control rod scale model and compact intermediate heat exchanger scale mode by current joining and assembly techniques. Joining methods for SiC to metal and results of characterization of joint shear strength by the torsion tests using small specimens were also reviewed. The recent results of neutron irradiation experiments were also reviewed including detailed analysis of mechanical properties, irradiation creep and preliminary results on tritium behavior in SiC.

  5. Molybdenum sulfide/carbide catalysts

    SciTech Connect (OSTI)

    Alonso, Gabriel (Chihuahua, MX); Chianelli, Russell R. (El Paso, TX); Fuentes, Sergio (Ensenada, MX); Torres, Brenda (El Paso, TX)

    2007-05-29T23:59:59.000Z

    The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

  6. Material characterization of the clay bonded silicon carbide candle filters and ash formations in the W-APF system after 500 hours of hot gas filtration at AEP. Appendix to Advanced Particle Filter: Technical progress report No. 11, January--March 1993

    SciTech Connect (OSTI)

    Alvin, M.A.

    1993-04-05T23:59:59.000Z

    (1) After 500 hours of operation in the pressurized fluidized-bed combustion gas environment, the fibrous outer membrane along the clay bonded silicon carbide Schumacher Dia Schumalith candles remained intact. The fibrous outer membrane did not permit penetration of fines through the filter wall. (2) An approximate 10-15% loss of material strength occurred within the intact candle clay bonded silicon carbide matrix after 500 hours of exposure to the PFBC gas environment. A relatively uniform strength change resulted within the intact candles throughout the vessel (i.e., top to bottom plenums), as well as within the various cluster ring positions (i.e., outer versus inner ring candle filters). A somewhat higher loss of material strength, i.e., 25% was detected in fractured candle segments removed from the W-APF ash hopper. (3) Sulfur which is present in the pressurized fluidized-bed combustion gas system induced phase changes along the surface of the binder which coats the silicon carbide grains in the Schumacher Dia Schumalith candle filter matrix.

  7. Optically initiated silicon carbide high voltage switch

    DOE Patents [OSTI]

    Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Sullivan, James S. (Livermore, CA); Sanders; David M. (Livermore, CA)

    2011-02-22T23:59:59.000Z

    An improved photoconductive switch having a SiC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

  8. ELECTROCHEMICAL MACHINING OF CARBIDES AND BORIDES

    E-Print Network [OSTI]

    Dissaux, Bernard Antoine

    2011-01-01T23:59:59.000Z

    behavior. The voltage oscillations were explained byextensively these voltage oscillations and, in contrast tovoltages and tool feed rates indicated that: • the oscillations

  9. Off-axis silicon carbide substrates

    DOE Patents [OSTI]

    Edgar, James; Dudley, Michael; Kuball, Martin; Zhang, Yi; Wang, Guan; Chen, Hui; Zhang, Yu

    2014-09-02T23:59:59.000Z

    A method of epitaxial growth of a material on a crystalline substrate includes selecting a substrate having a crystal plane that includes a plurality of terraces with step risers that join adjacent terraces. Each terrace of the plurality or terraces presents a lattice constant that substantially matches a lattice constant of the material, and each step riser presents a step height and offset that is consistent with portions of the material nucleating on adjacent terraces being in substantial crystalline match at the step riser. The method also includes preparing a substrate by exposing the crystal plane; and epitaxially growing the material on the substrate such that the portions of the material nucleating on adjacent terraces merge into a single crystal lattice without defects at the step risers.

  10. Silicon carbide oxidation in high temperature steam

    E-Print Network [OSTI]

    Arnold, Ramsey Paul

    2011-01-01T23:59:59.000Z

    The commercial nuclear power industry is continually looking for ways to improve reactor productivity and efficiency and to increase reactor safety. A concern that is closely regulated by the Nuclear Regulatory Commission ...

  11. Process for preparing silicon carbide foam

    DOE Patents [OSTI]

    Whinnery, L.L.; Nichols, M.C.; Wheeler, D.R.; Loy, D.A.

    1997-09-16T23:59:59.000Z

    A method of preparing near net shape, monolithic, porous SiC foams is disclosed. Organosilicon precursors are used to produce polymeric gels by thermally induced phase separation, wherein, a sufficiently concentrated solution of an organosilicon polymer is cooled below its solidification temperature to form a gel. Following solvent removal from the gel, the polymer foam is pretreated in an oxygen plasma in order to raise its glass transition temperature. The pretreated foam is then pyrolyzed in an inert atmosphere to form a SiC foam. 9 figs.

  12. Process for preparing silicon carbide foam

    DOE Patents [OSTI]

    Whinnery, LeRoy Louis (Livermore, CA); Nichols, Monte Carl (Livermore, CA); Wheeler, David Roger (Albuquerque, NM); Loy, Douglas Anson (Albuquerque, NM)

    1997-01-01T23:59:59.000Z

    A method of preparing near net shape, monolithic, porous SiC foams is disclosed. Organosilicon precursors are used to produce polymeric gels by thermally induced phase separation, wherein, a sufficiently concentrated solution of an organosilicon polymer is cooled below its solidification temperature to form a gel. Following solvent removal from the gel, the polymer foam is pretreated in an oxygen plasma in order to raise its glass transition temperature. The pretreated foam is then pyrolized in an inert atmosphere to form a SiC foam.

  13. Modelling Precipitation of Carbides in Martensitic Steels

    E-Print Network [OSTI]

    Cambridge, University of

    of Materials Science and Metallurgy, University of Cambridge, between October 2000 and November 2003. Except facilities in the Department of Materials Science and Metallurgy at the University of Cambridge. I would like of the physical metallurgy of secondary hardening steels and the phenomena of hydrogen embrittlement and hydrogen

  14. Silicon Carbide Derived Carbons: Experiments and Modeling

    SciTech Connect (OSTI)

    Kertesz, Miklos [Georgetown University, Washington DC 20057

    2011-02-28T23:59:59.000Z

    The main results of the computational modeling was: 1. Development of a new genealogical algorithm to generate vacancy clusters in diamond starting from monovacancies combined with energy criteria based on TBDFT energetics. The method revealed that for smaller vacancy clusters the energetically optimal shapes are compact but for larger sizes they tend to show graphitized regions. In fact smaller clusters of the size as small as 12 already show signatures of this �¢����graphitization�¢����. The modeling gives firm basis for the �¢����slit-pore�¢���� modeling of porous carbon materials and explains some of their properties. 2. We discovered small vacancy clusters and their physical characteristics that can be used to spectroscopically identify them. 3. We found low barrier pathways for vacancy migration in diamond-like materials by obtaining for the first time optimized reaction pathways.

  15. Modelling Precipitation of Carbides in Martensitic Steels

    E-Print Network [OSTI]

    Yamasaki, Shingo

    is greater than the yield stress of many commercial steels. II Sulfide stress corrosion cracking (SSCC) There were cases in which joints of pipes used in oil wells ruptured only a few days after the commencement of operation [45, 46]. These accidents were... -composition IG Intergranular fracture MVC Microvoid coalescence rupture MTDATA Metallurgical and Thermochemical Databank PC Pre-stressed concrete QC Quasi-cleavage fracture SSCC Sulfide stress corrosion cracking TEM Transmission electron microscope TMCP...

  16. Vanadium Carbide Coating Process | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your DensityEnergy U.S.-China Electric Vehicle and03/02 TUEValidation of Innovative ExplorationanValue

  17. Hybrid nuclear reactor grey rod to obtain required reactivity worth

    DOE Patents [OSTI]

    Miller, John V. (Munhall, PA); Carlson, William R. (Scott Township, Allegheny County, PA); Yarbrough, Michael B. (Hempfield Township, Westmoreland County, PA)

    1991-01-01T23:59:59.000Z

    Hybrid nuclear reactor grey rods are described, wherein geometric combinations of relatively weak neutron absorber materials such as stainless steel, zirconium or INCONEL, and relatively strong neutron absorber materials, such as hafnium, silver-indium cadmium and boron carbide, are used to obtain the reactivity worths required to reach zero boron change load follow. One embodiment includes a grey rod which has combinations of weak and strong neutron absorber pellets in a stainless steel cladding. The respective pellets can be of differing heights. A second embodiment includes a grey rod with a relatively thick stainless steel cladding receiving relatively strong neutron absorber pellets only. A third embodiment includes annular relatively weak netron absorber pellets with a smaller diameter pellet of relatively strong absorber material contained within the aperture of each relatively weak absorber pellet. The fourth embodiment includes pellets made of a homogeneous alloy of hafnium and a relatively weak absorber material, with the percentage of hafnium chosen to obtain the desired reactivity worth.

  18. Zirconium and Hafnium--2004 85. references that include a section mark () are found in the internet

    E-Print Network [OSTI]

    -mineral sand operations at Green cove Springs, fL; Stony creek, Va; and from its new mine in Lulaton, Ga. iluka of domestic mining operations. of the two domestic zircon producers, which have four mining and processing's florida operations included a dry mining mobile concentrator and a heavy-mineral sands processing plant

  19. Hafnium isotope evidence from Archean granitic rocks for deep-mantle origin of continental crust

    E-Print Network [OSTI]

    Mojzsis, Stephen J.

    of zircon crystallization. The advent of laser-ablation Lu­Hf isotope analysis of igneous and detrital

  20. Hafnium-doped tantalum oxide high-k gate dielectric films for future CMOS technology

    E-Print Network [OSTI]

    Lu, Jiang

    2007-04-25T23:59:59.000Z

    of the doped films were explained by their compositions and bond structures. The Hf-doped TaOx film is a potential high-k gate dielectric for future MOS transistors. A 5 Ã?Â? tantalum nitride (TaNx) interface layer has been inserted between the Hf-doped Ta...

  1. Nanocrystals Embedded Zirconium-doped Hafnium Oxide High-k Gate Dielectric Films

    E-Print Network [OSTI]

    Lin, Chen-Han

    2012-10-19T23:59:59.000Z

    , can be expected. In this study, the ZrHfO high-k MOS capacitors that separately contain nanocrystalline ruthenium oxide (nc-RuO), indium tin oxide (nc-ITO), and zinc oxide (nc-ZnO) have been successfully fabricated by the sputtering deposition method...

  2. Chemical Bonding, Interfaces and Defects in Hafnium Oxide/Germanium Oxynitride Gate Stacks on Ge (100)

    SciTech Connect (OSTI)

    Oshima, Yasuhiro; /Stanford U., Materials Sci. Dept.; Sun, Yun; /SLAC, SSRL; Kuzum, Duygu; /Stanford U.; Sugawara, Takuya; Saraswat, Krishna C.; Pianetta, Piero; /SLAC, SSRL; McIntyre, Paul C.; /Stanford U., Materials Sci. Dept.

    2008-10-31T23:59:59.000Z

    Correlations among interface properties and chemical bonding characteristics in HfO{sub 2}/GeO{sub x}N{sub y}/Ge MIS stacks were investigated using in-situ remote nitridation of the Ge (100) surface prior to HfO{sub 2} atomic layer deposition (ALD). Ultra thin ({approx}1.1 nm), thermally stable and aqueous etch-resistant GeO{sub x}N{sub y} interfaces layers that exhibited Ge core level photoelectron spectra (PES) similar to stoichiometric Ge{sub 3}N{sub 4} were synthesized. To evaluate GeO{sub x}N{sub y}/Ge interface defects, the density of interface states (D{sub it}) was extracted by the conductance method across the band gap. Forming gas annealed (FGA) samples exhibited substantially lower D{sub it} ({approx} 1 x 10{sup 12} cm{sup -2} eV{sup -1}) than did high vacuum annealed (HVA) and inert gas anneal (IGA) samples ({approx} 1x 10{sup 13} cm{sup -2} eV{sup -1}). Germanium core level photoelectron spectra from similar FGA-treated samples detected out-diffusion of germanium oxide to the HfO{sub 2} film surface and apparent modification of chemical bonding at the GeO{sub x}N{sub y}/Ge interface, which is related to the reduced D{sub it}.

  3. Method of Preparing Hydrous Hafnium, Cerium, or Aluminum Oxide Gels and

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHighand Retrievals from aRodMIT-HarvardEnergyMethod

  4. A look back at Union Carbides first 20 Years in Nuclear Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and 5,000 grams of enriched stable isotopes throughout the world for use in industry, agriculture, training and medicine. "RADIOISOTOPES FOR PEACEFUL USES" "The first...

  5. A look back at Union Carbides first 20 Years in Nuclear Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    months, and exhibited at the Atoms for Peace Conference in Geneva, Switzerland. "1956 - Thermonuclear fusion research expanded to develop a promising new approach to achieving a...

  6. Union Carbides Last 20 Years in Oak Ridge ? part 2

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    until finally shut down in 1987. (Rosenthal). 1962. A chemical explosion at the Paducah Gaseous Diffusion Plant resulted in a fire with damages estimated at 2 million. 1963. The...

  7. A look back at Union Carbides 20 Years in Nuclear Energy [The...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Chemicals Company was called in. On January 18, 1943, a contract to operate a gaseous diffusion plant and to provide engineering and research help was signed by James A....

  8. A look back at Union Carbides [first] 20 Years in Nuclear Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Construction started in October 1959. December 1961 - The new Development Laboratory for Chemistry and Physics departments of Technical Division was completed. Construction...

  9. Union Carbides Last 20 Years in Oak Ridge ? part 4

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1950s was to produce some highly enriched lithium-6 for use in building the first thermonuclear, also called the hydrogen or super-bomb. The project from the beginning was highly...

  10. A look back at Union Carbides FIRST 20 Years in Nuclear Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    "Radioisotopes are used as tracers in checking reactions in making chemicals and plastics. They permit accurate determinations that were impossible previously. "Agricultural...

  11. Union Carbides Last 20 Years in Oak Ridge ? part 3

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ion research facility at ORNL was named for Mr. Holifield instead. 1977. President Jimmy Carter announced that the next U. S. enrichment plant will be built at Portsmouth,...

  12. Union Carbides 20 years in nuclear energy, part 2

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    (Note: while not listed at the time because of the need for secrecy, Lithium separation production using the COLEX (column exchange) process began in Buildings 9201-4 and 9201-5...

  13. Occupational Medicine Implications of Engineered Nanoscale Particulate Matter

    E-Print Network [OSTI]

    Kelly, Richard J.

    2008-01-01T23:59:59.000Z

    Titanium Ytterbium Zirconium Animony Boron Carbon Cobalt Erbium Gallium Hafnium Iridium Lead Magnesium Neodymium Nitrogen

  14. Fact Sheet: Award-Winning Silicon Carbide Power Electronics ...

    Energy Savers [EERE]

    flywheels, electrochemical capacitors, superconducting magnetic energy storage (SMES), power electronics, and control systems, visit the Energy Storage page. Fact Sheet:...

  15. Optically-initiated silicon carbide high voltage switch

    DOE Patents [OSTI]

    Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Sullivan, James S. (Livermore, CA); Sanders, David M. (Livermore, CA)

    2012-02-28T23:59:59.000Z

    An improved photoconductive switch having a SIC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

  16. DIFFUSION OF MAGNESIUM AND MICROSTRUCTURES IN Mg+ IMPLANTED SILICON CARBIDE

    SciTech Connect (OSTI)

    Jiang, Weilin; Edwards, Danny J.; Jung, Hee Joon; Wang, Zheming; Zhu, Zihua; Roosendaal, Timothy J.; Hu, Shenyang Y.; Henager, Charles H.; Kurtz, Richard J.; Wang, Yongqiang

    2014-08-28T23:59:59.000Z

    Following our previous reports [ 1- 3], further isochronal annealing (2 hrs.) of the monocrystalline 6H-SiC and polycrystalline CVD 3C-SiC was performed at 1573 and 1673 K in Ar environment. SIMS data indicate that observable Mg diffusion in 6H-SiC starts and a more rapid diffusion in CVD 3C-SiC occurs at 1573 K. The implanted Mg atoms tend to diffuse deeper into the undamaged CVD 3C-SiC. The microstructure with Mg inclusions in the as-implanted SiC has been initially examined using high-resolution STEM. The presence of Mg in the TEM specimen has been confirmed based on EDS mapping. Additional monocrystalline 3C-SiC samples have been implanted at 673 K to ion fluence 3 times higher than the previous one. RBS/C analysis has been performed before and after thermal annealing at 1573 K for 12 hrs. Isothermal annealing at 1573 K is being carried out and Mg depth profiles being measured. Microstructures in both the as-implanted and annealed samples are also being examined using STEM.

  17. The effect of neutron irradiation on silicon carbide fibers

    SciTech Connect (OSTI)

    Newsome, G.A. [Lockheed Martin Corp., Schenectady, NY (United States)

    1997-01-01T23:59:59.000Z

    Nine types of SiC fiber have been exposed to neutron radiation in the Advanced Test Reactor at 250 C for various lengths of time ranging from 83 to 128 days. The effects of these exposures have been initially determined using scanning electron microscopy. The fibers tested were Nicalon{trademark} CG, Tyranno, Hi-Nicalon{trademark}, Dow Corning SiC, Carborundum SiC, Textron SCS-6, polymethysilane (PMS) derived SiC from the University of Michigan, and two types of MER SiC fiber. This covers a range of fibers from widely used commercial fibers to developmental fibers. Consistent with previous radiation experiments, Nicalon fiber was severely degraded by the neutron irradiation. Similarly, Tyranno suffered severe degradation. The more advanced fibers which approach the composition and properties of SiC performed well under irradiation. Of these, the Carborundum SiC fiber appeared to perform the best. The Hi-Nicalon and Dow Corning Fibers exhibited good general stability, but also appear to have some surface roughening. The MER fibers and the Textron SCS-6 fibers both had carbon cores which adversely influenced the overall stability of the fibers.

  18. High temperature Hexoloy{trademark} SX silicon carbide. Final report

    SciTech Connect (OSTI)

    Srinivasan, G.V.; Lau, S.K.; Storm, R.S. [Carborundum Co., Niagara Falls, NY (United States)

    1994-09-01T23:59:59.000Z

    HEXOLOY{reg_sign} SX-SiC, fabricated with Y and Al containing compounds as sintering aids, has been shown to possess significantly improved strength and toughness over HEXOLOY{reg_sign}SA-SiC. This study was undertaken to establish and benchmark the complete mechanical property database of a first generation material, followed by a process optimization task to further improve the properties. Mechanical characterization on the first generation material indicated that silicon-rich pools, presumably formed as a reaction product during sintering, controlled the strength from room temperature to 1,232 C. At 1,370 C in air, the material was failing due to a glass-phase formation at the surface. This glass-phase formation was attributed to the reaction of yttrium aluminates, which exist as a second phase in the material, with the ambient. This process was determined to be a time-dependent one that leads to slow crack growth. Fatigue experiments clearly indicated that the slow crack growth driven by the reaction occurred only at temperatures >1,300 C, above the melting point of the glass phase. Process optimization tasks conducted included the selection of the best SiC powder source, studies on mixing/milling conditions for SiC powder with the sintering aids, and a designed experiment involving a range of sintering and post-treatment conditions. The optimization study conducted on the densification variables indicated that lower sintering temperatures and higher post-treatment pressures reduce the Si-rich pool formation, thereby improving the room-temperature strength. In addition, it was also determined that furnacing configuration and atmosphere were critical in controlling the Si-rich formation.

  19. alternative lmfbr carbide: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the accelerator beam current. Calculations show that the maximal neutron flux in the thermal zone is 1014 cm12cdot s-1, in the fast booster zone is 5.12cdot1015...

  20. Silicon carbide whisker reinforced composites and method for making same

    DOE Patents [OSTI]

    Wei, G.C.

    1984-02-09T23:59:59.000Z

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties, especially increased fracture toughness. In the formation of these ceramic composites, the single-crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al/sub 2/O/sub 3/, mullite, or B/sub 4/C. The mixtures which contain a homogeneous dispersion of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600 to 1950/sup 0/C with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m/sup 1/2/ which represents as much as a two-fold increase over that of the matrix material.

  1. Quantitative analysis of inclusion distributions in hot pressed silicon carbide

    SciTech Connect (OSTI)

    Michael Paul Bakas

    2012-12-01T23:59:59.000Z

    ABSTRACT Depth of penetration measurements in hot pressed SiC have exhibited significant variability that may be influenced by microstructural defects. To obtain a better understanding regarding the role of microstructural defects under highly dynamic conditions; fragments of hot pressed SiC plates subjected to impact tests were examined. Two types of inclusion defects were identified, carbonaceous and an aluminum-iron-oxide phase. A disproportionate number of large inclusions were found on the rubble, indicating that the inclusion defects were a part of the fragmentation process. Distribution functions were plotted to compare the inclusion populations. Fragments from the superior performing sample had an inclusion population consisting of more numerous but smaller inclusions. One possible explanation for this result is that the superior sample withstood a greater stress before failure, causing a greater number of smaller inclusions to participate in fragmentation than in the weaker sample.

  2. amorphous silicon carbide: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high...

  3. ablating silicon carbide: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high...

  4. advanced silicon carbide: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high...

  5. aluminium carbides: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high...

  6. americium carbides: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high...

  7. Silicon carbide whisker-zirconia reinforced mullite and alumina ceramics

    DOE Patents [OSTI]

    Becher, Paul F. (Oak Ridge, TN); Tiegs, Terry N. (Lenoir City, TN)

    1987-01-01T23:59:59.000Z

    The flexural strength and/or fracture toughness of SiC whisker-reinforced composites utilizing mullite or alumina as the matrix material for the composite are increased by the addition of zirconia in a monoclinic or tetragonal phase to the matrix. The zirconia addition also provides for a lower hot-pressing temperature and increases the flexural strength and/or fracture toughness of the SiC whisker-reinforced composites over SiC whisker-reinforced composites of the similar matrix materials reinforced with similar concentrations of SiC whiskers.

  8. Union Carbide's 20 years in nuclear energy, part 1

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    chemical process, Y-12 makes significant contribution in the field of advanced metallurgy and special fabrication. A high-temperature furnace with hydrogen atmosphere used in...

  9. Harsh Environment Silicon Carbide Sensor Technology for Geothermal Instrumentation

    Broader source: Energy.gov [DOE]

    Project objectives: Develop advanced sensor technology for the direct monitoring of geothermal reservoirs. Engineer sensors to survive and operate in H2O pressures up to 220 bar and temperatures as high as 374o C.

  10. In situ electrochemical dilatometry of carbide-derived carbons

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the charge storage is purely based on double-layer charging. Therefore the ideal supercapacitor electrode should be free of charge induced microscopic structural changes....

  11. Conductive two-dimensional titanium carbide clay with high...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    into thin sheets, for a host of applications. When the rolled films were used as supercapacitor electrodes in a H 2 SO 4 electrolyte, the performances were extraordinary, with...

  12. UNION CARBIDE MZALS DIVISION tiiAGARA FALLS, NEW YDRK

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7 AugustAFRICAN3uj: ;;IDEC. i' , a .F.

  13. Silicon Carbide in the Cleanroom | GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol HomeFacebookScholarship Fund3 Outlook for Gulf ofMailing List Sign meInside the

  14. Harsh Environment Silicon Carbide Sensor Technology Geothermal Project |

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are8COaBulkTransmissionSitingProcess.pdfGetec AG| OpenInformation HandbookOhio: EnergyWestOhio:Rhode Island:

  15. Silicon Carbide Power Semiconductor Devices in the Cleanroom | GE Global

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our Instagram Secretary Moniz9 SeptemberSettingUncertainties ElitzaSignonSigns

  16. Ultratough, Thermally Stable Polycrystalline Diamond/Silicon Carbide

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page onYouTube YouTube Note: SinceDevelopment | Department of Energy $18 Million SolicitationNanocomposites for Drill Bits

  17. Making Silicon Carbide Devices in the Cleanroom | GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9November 6,Bradbury Effective Use ofSense

  18. ZIRCONIUM—HAFNIUM ISOTOPE EVIDENCE FROM METEORITES FOR THE DECOUPLED SYNTHESIS OF LIGHT AND HEAVY NEUTRON-RICH NUCLEI

    SciTech Connect (OSTI)

    Akram, W.; Schönbächler, M. [School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Sprung, P. [Institut für Planetologie, Universität Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany); Vogel, N. [Institute for Geochemistry and Petrology, ETH, Clausiusstrasse 25, 8092 Zürich (Switzerland)

    2013-11-10T23:59:59.000Z

    Recent work based on analyses of meteorite and terrestrial whole-rock samples showed that the r- and s- process isotopes of Hf were homogeneously distributed throughout the inner solar system. We report new Hf isotope data for Calcium-Aluminum-rich inclusions (CAIs) of the CV3 carbonaceous chondrite Allende, and novel high-precision Zr isotope data for these CAIs and three carbonaceous chondrites (CM, CO, CK). Our Zr data reveal enrichments in the neutron-rich isotope {sup 96}Zr (?1? in {sup 96}Zr/{sup 90}Zr) for bulk chondrites and CAIs (?2?). Potential isotope effects due to incomplete sample dissolution, galactic and cosmic ray spallation, and the nuclear field shift are assessed and excluded, leading to the conclusion that the {sup 96}Zr isotope variations are of nucleosynthetic origin. The {sup 96}Zr enrichments are coupled with {sup 50}Ti excesses suggesting that both nuclides were produced in the same astrophysical environment. The same CAIs also exhibit deficits in r-process Hf isotopes, which provides strong evidence for a decoupling between the nucleosynthetic processes that produce the light (A ? 130) and heavy (A > 130) neutron-rich isotopes. We propose that the light neutron-capture isotopes largely formed in Type II supernovae (SNeII) with higher mass progenitors than the supernovae that produced the heavy r-process isotopes. In the context of our model, the light isotopes (e.g. {sup 96}Zr) are predominantly synthesized via charged-particle reactions in a high entropy wind environment, in which Hf isotopes are not produced. Collectively, our data indicates that CAIs sampled an excess of materials produced in a normal mass (12-25 M{sub ?}) SNII.

  19. Push-out tests on a new silicon carbide/reaction-bonded silicon carbide ceramic matrix composite

    SciTech Connect (OSTI)

    Curtin, W.A. (BP Research, Cleveland, OH (United States)); Eldridge, J.I. (NASA Lewis Research Center, Cleveland, OH (United States)); Srinivasan, G.V. (Carborundum Co., Niagara Falls, NY (United States))

    1993-09-01T23:59:59.000Z

    Fiber push-out tests have been performed on a ceramic matrix composite consisting of Carborundum sintered SiC fibers, with a BN coating, embedded in a reaction-bonded SiC matrix. Analysis of the push-out data, utilizing the most complete theory presently available, shows that one of the fiber/coating/matrix interfaces has a low fracture energy (one-tenth that of the fiber) and a moderate sliding resistance [tau] [approximately] 8 MPa. The debonded sliding interface shows some continuous but minor abrasion, which appears to increase the sliding resistance, but overall the system exhibits very clean smooth sliding. The tensile response of a full-scale composite is then modeled, using data obtained here and known fiber strengths, to demonstrate the good composite behavior predicted for this material.

  20. High rate buffer layer for IBAD MgO coated conductors

    DOE Patents [OSTI]

    Foltyn, Stephen R. (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM); Arendt, Paul N. (Los Alamos, NM)

    2007-08-21T23:59:59.000Z

    Articles are provided including a base substrate having a layer of an oriented material thereon, and, a layer of hafnium oxide upon the layer of an oriented material. The layer of hafnium oxide can further include a secondary oxide such as cerium oxide, yttrium oxide, lanthanum oxide, scandium oxide, calcium oxide and magnesium oxide. Such articles can further include thin films of high temperature superconductive oxides such as YBCO upon the layer of hafnium oxide or layer of hafnium oxide and secondary oxide.

  1. Oxygen diffusion and reactions in Hf-based dielectrics L. V. Goncharova,a

    E-Print Network [OSTI]

    Gustafsson, Torgny

    Oxygen diffusion and reactions in Hf-based dielectrics L. V. Goncharova,a M. Dalponte, D. G Oxygen transport in and reactions with thin hafnium oxide and hafnium silicate films have been. The exchange rate is faster for pure hafnium oxides than for silicates. The amount of exchanged oxygen

  2. Activation cross sections of $?$-particle induced nuclear reactions on hafnium and deuteron induced nuclear reaction on tantalum: production of $^{178}$W/$^{178m}$Ta generator

    E-Print Network [OSTI]

    F. Tárk'anyi; S. Tak'acs; F. Ditrói; A. Hermanne; A. V. Ignatyuk; M. S. Uddin

    2014-12-01T23:59:59.000Z

    In the frame of a systematic study of charged particle production routes of medically relevant radionuclei, the excitation function for indirect production of $^{178m}$Ta through $^{nat}$Hf($\\alpha$,xn)$^{178}$W-$^{178m}$Ta nuclear reaction was measured for the first time up to 40 MeV. In parallel, the side reactions $^{nat}$Hf($\\alpha$,x)$^{179,177,176,175}$W, $^{183,182,178g,177,176,175}$Ta, $^{179m,177m,175}$Hf were also assessed. Stacked foil irradiation technique and $\\gamma$-ray spectrometry were used. New experimental cross section data for the $^{nat}$Ta(d,xn)$^{178}$W reaction are also reported up to 40 MeV. The measured excitation functions are compared with the results of the ALICE-IPPE, and EMPIRE nuclear reaction model codes and with the TALYS 1.4 based data in the TENDL-2013 library. The thick target yields were deduced and compared with yields of other charged particle ((p,4n), (d,5n) and ($^3$He,x)) production routes for $^{178}$W.

  3. Evolution of E2 transition strength in deformed hafnium isotopes from new measurements on $^{172}$Hf, $^{174}$Hf, and $^{176}$Hf

    E-Print Network [OSTI]

    M. Rudigier; K. Nomura; M. Dannhoff; R-B. Gerst; J. Jolie; N. Saed-Samii; S. Stegemann; J-M. Régis; L. M. Robledo; R. Rodríguez-Guzmán; A. Blazhev; Ch. Fransen; N. Warr; K. O. Zell

    2015-04-07T23:59:59.000Z

    The available data for E2 transition strengths in the region between neutron-deficient Hf and Pt isotopes are far from complete. More and precise data are needed to enhance the picture of structure evolution in this region and to test state-of-the-art nuclear models. In a simple model, the maximum collectivity is expected at the middle of the major shell. However, for actual nuclei, this picture may no longer be the case, and one should use a more realistic nuclear-structure model. We address this point by studying the spectroscopy of Hf. We remeasure the 2^+_1 half-lives of 172,174,176Hf, for which there is some disagreement in the literature. The main goal is to measure, for the first time, the half-lives of higher-lying states of the rotational band. The new results are compared to a theoretical calculation for absolute transition strengths. The half-lives were measured using \\gamma-\\gamma and conversion-electron-\\gamma delayed coincidences with the fast timing method. For the determination of half-lives in the picosecond region, the generalized centroid difference method was applied. For the theoretical calculation of the spectroscopic properties, the interacting boson model is employed, whose Hamiltonian is determined based on microscopic energy-density functional calculations. The measured 2^+_1 half-lives disagree with results from earlier \\gamma-\\gamma fast timing measurements, but are in agreement with data from Coulomb excitation experiments and other methods. Half-lives of the 4^+_1 and 6^+_1 states were measured, as well as a lower limit for the 8^+_1 states. We show the importance of the mass-dependence of effective boson charge in the description of E2 transition rates in chains of nuclei. It encourages further studies of the microscopic origin of this mass dependence. New data on transition rates in nuclei from neighboring isotopic chains could support these studies.

  4. Development of single crystal filaments. Final report

    SciTech Connect (OSTI)

    Milewski, J.V.; Shoultz, R.A.; Bourque-McConnell, M.M.

    1995-04-01T23:59:59.000Z

    The program just completed addresses a route to a more efficient longer-lasting electric light bulb filament. All current filaments for light bulbs are metallic in nature. They are subject to embrittlement with age (large grain growth) and relatively high vapor pressures which limits their operating temperature. There is evidence which suggests advantages to using high temperature refractory single crystal fibers as a filament for a light bulb. These refractory materials may include materials such as hafnium or tantalum carbide which have melting points about 500{degrees}C higher than tungsten. Another advantage is that single crystal fibers have a very high degree of crystalline perfection with very few voids and dislocations. Without these imperfections, the atomic mobility at high temperatures is highly restricted. Thus single crystal fibers are very stable at high temperature and will last longer. The efficiencies result from running these single crystal ceramic fiber filaments at higher temperatures and the higher emissivity of the carbide filaments compared to tungsten. The amount of visible light is proportional to the 4the power of the temperature thus a 500{degrees}C higher operating give about a 3-fold increase in radiation in the visible range. The program accomplishments can be summarized as follows: (1) Single crystal fibers of JfC sufficient crystal quality for light bulb filament applications were made. (2) The HfC fiber furnace growth chamber, power control and data collection system was developed for the laboratory scale plant. (3) method for mounting and apparatuses for testing the single crystal fiber filaments were developed and built.

  5. Design of a core-length thermionic fuel element for electrical heating

    SciTech Connect (OSTI)

    Miskolczy, G. (ThermoTrex Coporation, 85 First Avenue, P.O. Box 8995, Waltham, MA 02254-8995 (United States)); Horner, H. (General Atomics, 3550 General Atomics Court, P.O. Box 85608, San Diego, CA 92186-9784 (United States)); Lamp, T. (Wright Laboratories, WL/POOC-2, Wright Patternson Air Force Base, Ohio 45433-6563 (United States))

    1993-01-20T23:59:59.000Z

    This paper describes the design of an electrically heated version of a core-length Thermionic Fuel Element (TFE) with advanced features, as is suggested by the designation Advanced Thermionic Inititative (ATI). The advanced features include a high-strength emitter structure to be fabricated by Space Power, Incorporated. This structure consists of a cylindrical emitter, 15 mm diameter and 254 mm long of Chemically Vapor Deposited (CVD) tungsten, reinforced with tungsten-hafnium carbide wire wound over a CVD tungsten core with additional CVD tungsten incorporating and bonding the wire into the emitter. The emitter surface is CVD tungsten, deposited from tungsten chloride resulting in the desirable crystal orientation of [l angle]110[r angle]. It is possible to design a reactor with core-length TFEs so that it can be electrically tested prior to fueling. The program is focussed on the design and fabrication of a single core-length TFE with current collection at both ends which will be tested in a reactor. In parallel with this effort is the design, fabrication, and testing of an unfueled, electrically heated prototype. The intent is to make the electrically heated converter as similar as possible to the fueled one, while providing for accurate emitter and collector temperature measurement.

  6. High temperature 4H-silicon carbide thyristors and power MOSFETs

    SciTech Connect (OSTI)

    Palmour, J.W.; Allen, S.T.; Singh, R.; Lipkin, L.A.; Waltz, D.G. [Cree Research, Inc., 2810 Meridian Parkway, Durham, North Carolina 27713 (United States)

    1996-03-01T23:59:59.000Z

    Two types of high temperature power switches, MOSFETs and thyristors, have been demonstrated in 4H-SiC. Vertical UMOS power MOSFETs have been demonstrated to block voltages as high as 260 V with a specific on-resistance of 18 m{Omega}-cm{sup 2}. Larger area, 175 V MOSFETs had a rated current of 2 Amps (200 A/cm{sup 2}) at {ital V}{sub {ital d}}=2.65 V. Previous 4H-SiC UMOS MOSFETs were measured to operate up to 573 K. 4H-SiC npnp thyristors have been successfully operated up to 773 K, and have achieved blocking voltages of 600 V and an on-current of 1.8 A. Larger area, 200 V thyristors had a rated current of 10 Amps (620 A/cm{sup 2}) with a voltage drop of 3.6 V. Current densities as high as 1000 A/cm{sup 2} at {minus}4.0 V has also been achieved. The thyristors have also shown very fast turn-off times, ranging from 360{endash}640 nsec. {copyright} {ital 1996 American Institute of Physics.}

  7. HIGH RESOLUTION SCANNING AUGER MICROANALYSIS OF HIGH-STRENGTH SILICON CARBIDES

    E-Print Network [OSTI]

    Krivanek, O.L.

    2012-01-01T23:59:59.000Z

    Energy Sciences. Contract #W-7405-ENG- 48). REFERENCES l. S.Energy under Contract W-7405-ENG-48 DISCLAIMER This document

  8. Coprocessed nuclear fuels containing (U, Pu) values as oxides, carbides or carbonitrides

    DOE Patents [OSTI]

    Lloyd, Milton H. (Oak Ridge, TN)

    1983-01-01T23:59:59.000Z

    Method for direct coprocessing of nuclear fuels derived from a product stream of a fuels reprocessing facility containing uranium, plutonium, and fission product values comprising nitrate stabilization of said stream vacuum concentration to remove water and nitrates, neutralization to form an acid deficient feed solution for the internal gelation mode of sol-gel technology, green spherule formation, recovery and treatment for loading into a fuel element by vibra packed or pellet formation technologies.

  9. Coprocessed nuclear fuels containing (U, Pu) values as oxides, carbides or carbonitrides

    DOE Patents [OSTI]

    Lloyd, M.H.

    1981-01-09T23:59:59.000Z

    Method for direct coprocessing of nuclear fuels derived from a product stream of fuels reprocessing facility containing uranium, plutonium, and fission product values comprising nitrate stabilization of said stream vacuum concentration to remove water and nitrates, neutralization to form an acid deficient feed solution for the internal gelation mode of sol-gel technology, green spherule formation, recovery and treatment for loading into a fuel element by vibra packed or pellet formation technologies.

  10. Polypyrrole/Silicon Carbide Nanocomposites with Tunable Electrical Conductivity Pallavi Mavinakuli,

    E-Print Network [OSTI]

    Guo, John Zhanhu

    *, Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar UniVersity, Beaumont, Texas 77710, Department of Chemistry and Physics, Lamar UniVersity, Beaumont, Texas 77710

  11. Intern experience at the Union Carbide Corporation, Texas City plant: an internship report 

    E-Print Network [OSTI]

    Tippett, Donald Dwight, 1947-

    2013-03-13T23:59:59.000Z

    intern attached to the Maintenance Department, with access to virtually every staff and line component of the organization. The intent of this report is to demonstrate that this experience fulfills the requirements of the Doctor...

  12. Sulfur surface chemistry on the platinum gate of a silicon carbide based hydrogen sensor

    E-Print Network [OSTI]

    Tobin, Roger G.

    monitoring, solid-oxide fuel cells, and coal gasification, require operation at much higher temperatures than the magnitude of the sensor's response to alternating hydrogen and oxygen pulses by about 70%, as compared-based devices and the understanding of their operation.10­12 The sensing mechanism involves several steps. 1

  13. Structural changes induced by heavy ion irradiation in titanium silicon carbide J.C. Nappa,

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    .80.-x, 61.80.Lj, 25.75.Ag, 34.50.Bw, 28.41.Bm, 61.05.C-, 68.37.Og 1. Introduction The Gas Fast Reactor thermomechanical properties, are sensed to manufacture the fuel cladding of Generation IV reactors that should work

  14. Short-and intermediate-range structural correlations in amorphous silicon carbide: A molecular dynamics study

    E-Print Network [OSTI]

    Southern California, University of

    with the presence of structural defects. For this purpose inelastic neutron-scattering and neutron- diffraction Federal de São Carlos, São Carlos, SP, Brazil 3 Studsvik Neutron Research Laboratory, University

  15. Effects of coal slag corrosion on the mechanical properties of sintered {alpha}-silicon carbide

    SciTech Connect (OSTI)

    Hannel, S.E. [Ecole Centrale, Lyon (France); Breder, K.; Joslin, D.L. [Oak Ridge National Lab., TN (United States)

    1997-03-01T23:59:59.000Z

    Tubes of sintered SiC were exposed for 500 h in a laboratory furnace to three different coal slags at three temperatures. No corrosive attack or strength reduction was observed after exposure at 1090{degrees}C. At 1260{degrees}C the least viscous slag caused formation of corrosion pits and loss of strength. At 1430{degrees}C formation of iron silicides at the interface between the slag and the base material caused severe loss of strength for slags with the highest and the lowest viscosity, while the specimens exposed to the slag with medium viscosity and medium iron content survived quite well. The results show that mechanical strength can be retained for certain coal slag - temperature combinations.

  16. Thermodynamic stability of oxide, nitride, and carbide coating materials in liquid Sn25Li

    E-Print Network [OSTI]

    Ghoniem, Nasr M.

    as breeder material for blanket applications and concluded that the low breeding ratio offsets the low vapor

  17. HIGH RESOLUTION SCANNING AUGER MICROANALYSIS OF HIGH-STRENGTH SILICON CARBIDES

    E-Print Network [OSTI]

    Krivanek, O.L.

    2012-01-01T23:59:59.000Z

    Society HIGH RESOLUTION SCANNING AUGER MICROANALYSIS OFCalifornia. HIGH RESOLUTION SCANNING AUGER MICROANALYSIS OFhelium, by high resolution scanning Auger microanalysis and

  18. Development of a hot isostatic pressing process for manufacturing silicon carbide particulate reinforced iron

    E-Print Network [OSTI]

    Oakeson, David Oscar

    1992-01-01T23:59:59.000Z

    was machined to contain the bottom portion of the evacuation tube, removing the weld surface for these two parts from the disk region of the cap and decreasing the rigidity of the cap. This was recommended by previous research for the purpose of making... DIM IN INCHES 9/18/1991 Figure 3 Container Bottom Cap Specifications 20 machined, they were rinsed with methanol to remove the cutting fluids. Before welding, the cap was held in place by a slight press fit. The bottom cap was welded into place...

  19. Tungsten carbide synthesized by low-temperature combustion as gas diffusion electrode catalyst

    E-Print Network [OSTI]

    Volinsky, Alex A.

    of Science and Technology Beijing, Beijing 100083, China b Departament Fi´sica Aplicada, EETAC, Universitat Polite`cnica de Catalunya e BarcelonaTech, 08860 Castelldefels, Spain c Department of Metallurgical performance, comparable with that of Pt. Copyright ª 2014, Hydrogen Energy Publications, LLC. Published

  20. Method for improving the toughness of silicon carbide-based ceramics

    DOE Patents [OSTI]

    Tein, T.Y.; Hilmas, G.E.

    1996-12-03T23:59:59.000Z

    Method of improving the toughness of SiC-based ceramics is disclosed. SiC, , AlN, Al{sub 2}O{sub 3} and optionally {alpha}-Si{sub 3}N{sub 4} are hot pressed to form a material which includes AlN polytypoids within its structure. 1 fig.

  1. Thermal Conductivity and Seebeck Coefficients of Icosahedral Boron Arsenide Films on Silicon Carbide

    SciTech Connect (OSTI)

    Y Gong; Y Zhang; M Dudley; Y Zhang; J Edgar; P Heard; M Kuball

    2011-12-31T23:59:59.000Z

    The thermal conductivity of icosahedral boron arsenide (B{sub 12}As{sub 2}) films grown on (0001) 6H-SiC substrates by chemical vapor deposition was studied by the 3{omega} technique. The room temperature thermal conductivity decreased from 27.0 to 15.3 W/m K as the growth temperature was decreased from 1450 to 1275 C. This is mainly attributed to the differences in the impurity concentration and microstructure, determined from secondary ion mass spectrometry and high resolution transmission electron microscopy, respectively. Callaway's theory was applied to calculate the temperature-dependent thermal conductivity, and the results are in good agreement with the experimental data. Seebeck coefficients were determined as 107 {micro}V/K and 136 {micro}V/K for samples grown at 1350 C with AsH{sub 3}/B{sub 2}H{sub 6} flow ratio equals to 1:1 and 3:5, respectively.

  2. On the Cover: Schematic of a silicon carbide ceramic in an active atmosphere.

    E-Print Network [OSTI]

    Theory and Practice Certain commercial entities, equipment, or materials may be identified is it intended to imply that the entities, materials, or equipment are necessarily the best available Data evaluation is the process by which collections of data are assessed with respect to reliability

  3. Optically-initiated silicon carbide high voltage switch with contoured-profile electrode interfaces

    DOE Patents [OSTI]

    Sullivan, James S.; Hawkins, Steven A.

    2012-09-04T23:59:59.000Z

    An improved photoconductive switch having a SiC or other wide band gap substrate material with opposing contoured profile cavities which have a contoured profile selected from one of Rogowski, Bruce, Chang, Harrison, and Ernst profiles, and two electrodes with matching contoured-profile convex interface surfaces.

  4. Silicon carbide process development for microengine applications : residual stress control and microfabrication

    E-Print Network [OSTI]

    Choi, Dongwon, 1973-

    2004-01-01T23:59:59.000Z

    The high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high speed at elevated temperatures (1300 to 1700 K). ...

  5. Process development of silicon-silicon carbide hybrid structures for micro-engines (January 2002)

    E-Print Network [OSTI]

    Choi, D.

    MEMS-based gas turbine engines are currently under development at MIT for use as a button-sized portable power generator or micro-aircraft propulsion sources. Power densities expected for the micro-engines require very ...

  6. Development of a hot isostatic pressing process for manufacturing silicon carbide particulate reinforced iron 

    E-Print Network [OSTI]

    Oakeson, David Oscar

    1992-01-01T23:59:59.000Z

    to aluminum, titanium, and some other metals and alloys. However, information obtained in processing iron can be used in developing guidelines for processing other metals. For example, the processing temperature as a fraction of the melting temperature... processes can be used for particulate reinforced MMCs which would break whisker or fiber reinforcements. ~' Conse- quently, particulate reinforced MMCs have appeared in other industries and have been demonstrated in applications including aluminum...

  7. Method for improving the toughness of silicon carbide-based ceramics

    DOE Patents [OSTI]

    Tein, Tseng-Ying (Ann Arbor, MI); Hilmas, Gregory E. (Dexter, MI)

    1996-01-01T23:59:59.000Z

    Method of improving the toughness of SiC-based ceramics. SiC, , AlN, Al.sub.2 O.sub.3 and optionally .alpha.-Si.sub.3 N.sub.4 are hot pressed to form a material which includes AlN polytypoids within its structure.

  8. Analysis of silicon carbide based semiconductor power devices and their application in power factor correction 

    E-Print Network [OSTI]

    Durrani, Yamin Qaisar

    2005-11-01T23:59:59.000Z

    ......................................................... 6 1.3.1 Flyback converter based PFC..................................................... 9 1.3.2 Boost converter based PFC....................................................... 10 1.3.3 Dual boost PFC scheme............................................................... 11 1.4. High frequency operation of PFC...................................................... 12 1.5. SiC based power devices in switching power converters.................. 13 1.6. Research objective...

  9. Silicon carbide performance as cladding for advanced uranium and thorium fuels for light water reactors

    E-Print Network [OSTI]

    Sukjai, Yanin

    2014-01-01T23:59:59.000Z

    There has been an ongoing interest in replacing the fuel cladding zirconium-based alloys by other materials to reduce if not eliminate the autocatalytic and exothermic chemical reaction with water and steam at above 1,200 ...

  10. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOE Patents [OSTI]

    Wei, George C.

    1993-11-16T23:59:59.000Z

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous disperson of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.075 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.

  11. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOE Patents [OSTI]

    Wei, George C. (Oak Ridge, TN)

    1985-01-01T23:59:59.000Z

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous dispersion of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.

  12. Aligned Carbon Nanotube Reinforced Silicon Carbide Composites by Chemical Vapor Infiltration

    SciTech Connect (OSTI)

    Gu, Zhan Jun [University of Georgia, Athens, GA; Yang, Ying Chao [University of South Carolina, Columbia; Li, Kai Yuan [University of Georgia, Athens, GA; Tao, Xin Yong [University of South Carolina, Columbia; Eres, Gyula [ORNL; Howe, Jane Y [ORNL; Zhang, Li Tong [Northwestern Polytechnical University, Xi'an, China; Li, Xiao Dong [University of South Carolina, Columbia; Pan, Zhengwei [ORNL

    2011-01-01T23:59:59.000Z

    Owing to their exceptional stiffness and strength1 4, carbon nanotubes (CNTs) have long been considered to be an ideal reinforcement for light-weight, high-strength, and high-temperature-resistant ceramic matrix composites (CMCs)5 10. However, the research and development in CNT-reinforced CMCs have been greatly hindered due to the challenges related to manufacturing including poor dispersion, damages during dispersion, surface modification, densification and sintering, weak tube/matrix interfaces, and agglomeration of tubes at the matrix grain boundaries5,11. Here we report the fabrication of high-quality aligned CNT/SiC composites by chemical vapor infiltration (CVI), a technique that is being widely used to fabricate commercial continuous-filament CMCs12 15. Using the CVI technique most of the challenges previously encountered in the fabrication of CNT composites were readily overcome. Nanotube pullouts, an important toughening mechanism for CMCs, were consistently observed on all fractured CNT/SiC samples. Indeed, three-point bending tests conducted on individual CNT/SiC nanowires (diameters: 50 200 nm) using an atomic force microscope show that the CNT-reinforced SiC nanowires are about an order of magnitude tougher than the bulk SiC. The tube/matrix interface is so intimate and the SiC matrix is so dense that a ~50-nm-thick SiC coating can effectively protect the inside nanotubes from being oxidized at 1600 C in air. The CVI method may be extended to produce nanotube composites from a variety of matrix

  13. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOE Patents [OSTI]

    Wei, George C. (Oak Ridge, TN)

    1993-01-01T23:59:59.000Z

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous disperson of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.075 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.

  14. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOE Patents [OSTI]

    Wei, G.C.

    1989-01-24T23:59:59.000Z

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al{sub 2}O{sub 3}, mullite, or B{sub 4}C. The mixtures which contain a homogeneous dispersion of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1,600 to 1,950 C with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness which represents as much as a two-fold increase over that of the matrix material.

  15. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOE Patents [OSTI]

    Wei, George C. [Oak Ridge, TN

    1989-01-24T23:59:59.000Z

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous disperson of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MP.am.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.

  16. Analysis of silicon carbide based semiconductor power devices and their application in power factor correction

    E-Print Network [OSTI]

    Durrani, Yamin Qaisar

    2005-11-01T23:59:59.000Z

    electronic switching devices................. 22 2.4.1. SiC Schottky diode................................................................. 22 2.4.2. 4H-SiC PiN diode................................................................... 23 2.4.3. Si...C MOSFET.......................................................................... 23 2.4.4. SiC JFET................................................................................. 23 2.5. Analysis of SiC based Schottky diode...

  17. Magnetic properties and scale-up of nanostructured cobalt carbide permanent magnetic powders

    SciTech Connect (OSTI)

    Zamanpour, Mehdi, E-mail: zamanpour.m@husky.neu.edu; Bennett, Steven; Taheri, Parisa; Chen, Yajie [Center for Microwave Magnetic Materials and Integrated Circuits, Northeastern University, Boston, Massachusetts 02115 (United States); Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits, Northeastern University, Boston, Massachusetts 02115 (United States); Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States)

    2014-05-07T23:59:59.000Z

    Co{sub x}C magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co{sub 2}C and Co{sub 3}C phases possessing magnetization values exceeding 45?emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of surfactants, reaction temperature, and reaction duration on the crystallographic structure and magnetic properties of Co{sub x}C, while tetraethylene glycol was employed as a reducing agent. The role of the ratios of Co{sub 2}C and Co{sub 3}C phases in the admixture magnetic properties is discussed. The crystallographic structure and particle size of the Co{sub x}C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties.

  18. Intern experience at the Union Carbide Corporation, Texas City plant: an internship report

    E-Print Network [OSTI]

    Tippett, Donald Dwight, 1947-

    2013-03-13T23:59:59.000Z

    of the tasks. Based on the task inventory results, an apprentice training program is designed. This method produces a craftsman who is more thoroughly trained in the specific skills he EMP UOV E REL ATI ONS D EP AR TM EN T 14 Ciu PCI 5c/jA t..., the progress of various individuals was discussed. Also, future re? quirements were analyzed to determine how many apprentices must enter the program now in order to fill craft needs four years hence. Since it does take four years to train a journeyman...

  19. Properties of nanostructured diamond-silicon carbide composites sintered by high pressure infiltration technique

    E-Print Network [OSTI]

    Gubicza, Jenõ

    peak profiles using Fourier coefficients of ab initio theoretical size and strain profiles Materials Research Society 2703 #12;electric power dissipated in the apparatus. Obtained power­ temperature and load­pressure plots were used as the calibration curves for subsequent high-pressure, high- temperature

  20. Boron Carbide and Silicon Oxide Hetero-nanonecklaces via Temperature Modulation

    E-Print Network [OSTI]

    Gao, Hongjun

    ) nanostructures have shown great potential as unique building blocks for fabrication of advanced electronic devices, including field-effect transistors (FETs),1­3 logic circuits,4 inverters5 and decoders.6 Due properties for integration in novel functional nanosystems. Some work on 1D hetero

  1. aluminide-bonded carbide ceramics: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    j and the magnetic field H in Bi2Sr2CaCu2O8 x ceramics. We provided in high-Tc superconduct- ing granular ceramics remain an intriguing subject of inten- sive investigations...

  2. Modeling the infiltration kinetics of molten aluminum into porous titanium carbide

    SciTech Connect (OSTI)

    Muscat, D. (Univ. of Malta, Msida (Malta). Dept. of Metallurgy and Materials Engineering); Drew, R.A.L. (McGill Univ., Montreal, Quebec (Canada))

    1994-11-01T23:59:59.000Z

    Capillary-induced melt infiltration is an attractive method of fabricating metal/ceramic composites, as it offers the advantage of producing material with a high ceramic content and near-net-shape fabrication, without the use of an external force. In this work, the kinetics of infiltration of molten Al in TiC preforms, having a pore size of approximately 1[mu]m and porosity ranging from 20 to 40 pct, were investigated. The rate of infiltration was continuously monitored using a Thermo-Gravimetric analyzer (TGA), which measured the weight change of the preform as the metal intruded the sample. Infiltration profiles were generated over a temperature range of 860 C to 1,085 C. At lower temperatures, an incubation period was evident in the profiles. The average activation energy for the different preforms was 90 kJ/mol, indicating that some form of mass-transfer mechanisms was involved in driving the process. Furthermore, sessile drop tests showed an unstable wetting angle over a long period of time. Such wetting kinetics were responsible for the incubation period during the infiltration. The infiltration rate was also seen to be slower as the preform density increased. This was due to the tortuous nature of the channels and was characterized using curves obtained for liquids infiltrating the same preforms at room temperature. Both the tortuosity and the unstable contact angle have to be considered when modeling the infiltration kinetics of such a system. The existing model was therefore modified by incorporating terms to describe the process more accurately. A good correlation with the experimental data was seen to exist.

  3. I' I OAK RIDGE NATIONAL LABORATORY OPERATED B Y UNION CARBIDE CORPORATION

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7111AWell:F E ,"^ I 1' . _ .t.fiom/ I' I OAK

  4. Fact Sheet: Award-Winning Silicon Carbide Power Electronics (October 2012)

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 1112011AT&T,OfficeEnd ofEvaluations in Covered Facilities | DepartmentFact Sheet:Silicon

  5. Fact Sheet: Award-Winning Silicon Carbide Power Electronics (October 2012)

    Office of Environmental Management (EM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33 1112011 Strategic Plan| Department of.pdf6-OPAMDepartment6 FY 2007FYFacilityDepartment of|

  6. Ultratough, Thermally Stable Polycrystalline Diamond/Silicon Carbide Nanocomposites for Drill Bits

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your DensityEnergy U.S.-China Electric Vehicle and BatteryUS-EU-JapanCatalysts | DepartmentBoilers |Ultratough,

  7. OAK RIDGE NATIONAL LABORATORY OPER*TEO BY UNION CARBIDE CORPORATION

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7 AugustAFRICAN .METALS~ C~RPO~~XON~$ ., . .Y.'

  8. PRELIMINARY SURVEY OF THE UNION CARBIDE CORPORATION METALS DIVISION PLANT, NIAGARA FALLS, NEW YORK

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7 AugustAFRICAN .METALS~TEXAS CITY CHEMICALS,e -

  9. DOE - Office of Legacy Management -- Union Carbide and Carbon Co - TN 10

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling Corp -K LeDowntown SiteTracerlabPARadium

  10. Ductile aluminide alloys for high temperature applications

    DOE Patents [OSTI]

    Liu, C.T.; Stiegler, J.O.

    1983-12-21T23:59:59.000Z

    Improved Ni/sub 3/Al alloys are provided by inclusion of boron, hafnium or zirconium, and in some species, iron.

  11. Selective Synthesis of "Left-Handed" or "Right-Handed" Chemicals...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    other catalysts produce a mixture of both enantiomers. Researchers studied hafnium, titanium and zirconium (Group 4) containing catalysts and found the zirconium catalysts to be...

  12. APS Colloquium logo

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    July 7, 2004 John Schiffer Physics Division, Argonne National Laboratory "The Hafnium saga: Can radioactive decay be usefully controlled?" John Schiffer has been at Argonne for a...

  13. New Target Methodology: Polymer-Assisted Deposition and Its Applications on Gas-Phase Nuclear Chemistry with Rutherfordium

    E-Print Network [OSTI]

    Garcia, Mitch Andre

    2009-01-01T23:59:59.000Z

    metal oxides of hafnium, europium, and thulium on siliconion concentration of europium(III) oxide study the oxide films of europium (Eu) and thulium (Tm) as

  14. Early transition metal catalysts for the living polymerization of olefins and alkynes

    E-Print Network [OSTI]

    Adamchuk, Jennifer

    2006-01-01T23:59:59.000Z

    Zirconium and Hafnium Ziegler-Natta catalysts containing the [(2,6- C12C6H3NCH2CH2)2NMe]2- ([ArciN2NMe]2') ligand were prepared and employed in the polymerization of 1-hexene. Hafnium Ziegler-Natta catalysts containing the ...

  15. Development and testing of radiation- and electromagnetic-pulse hardened silicon-carbide-based electronics. Quarterly report

    SciTech Connect (OSTI)

    Edmond, J.A.; Palmour, J.W.

    1990-09-19T23:59:59.000Z

    There were three primary objectives. The first was the reverse avalanche testing of diodes exhibiting (a) microplasma dominated breakdown, (b) a combination of microplasma and bulk avalanche breakdown and (c) bulk avalanche breakdown only. These glass encapsulated devices were tested at approximately 1 us, approximately 10 us and 100 us pulses. The second objective was to fabricate and characterize Shockley diodes in chip form showing proper breakdown in forward and reverse bias and a forward bias turn-on of approximately 2.6 V. The third objective was to fabricate and characterize 6H-SiC JFET structures in chip form.

  16. Fabrication of Carbide-Particle-Reinforced Titanium AluminideMatrix Composites by Laser-Engineered Net Shaping

    E-Print Network [OSTI]

    DuPont, John N.

    -temperature applications in the automotive, aerospace, and power-generation industries.[1] The TiAl-based alloys have-Engineered Net Shaping WEIPING LIU and J.N. DuPONT TiAl-based titanium aluminide alloys and their composites of the Ti-6Al-4V alloy. I. INTRODUCTION TITANIUM aluminide alloys based on TiAl and their com- posites

  17. Accuracy of truncated Leiden and Berlin virial expansions for pure gases and sealing joints between silicon carbide and stainless steel 

    E-Print Network [OSTI]

    Santana Rodriguez, Gabriel Enrique

    2003-01-01T23:59:59.000Z

    . An alternative to overcome this problem in brazing is using a functionally graded material (FGM) that is formed with the native elements. This FGM has one end of almost 100% stainless steel, which is joined using very well known processes of joining metals...

  18. Engineering scale development of the vapor-liquid-solid (VLS) process for the production of silicon carbide fibrils. Phase 2

    SciTech Connect (OSTI)

    Ohnsorg, R.W.; Hollar, W.E. Jr.; Lau, S.K. [Carborundum Co., Niagara Falls, NY (United States). Technology Div.; Ko, F.K.; Schatz, K. [Advanced Product Development, Bristol, PA (United States)

    1995-04-01T23:59:59.000Z

    As reinforcements for composites, VLS SiC fibrils have attractive mechanical properties including high-strength, high modulus, and excellent creep resistance. To make use of their excellent mechanical properties in a composite, a significant volume fraction (>10%) of aligned, long fibrils (>2 mm) needs to be consolidated in the ceramic matrix. The fibrils must be processed into an assembly that will allow for composite fabrication while maintaining fibril alignment and length. With Advanced Product Development (APD) as the yam fabrication subcontractor, Carborundum investigated several approaches to achieve this goaL including traditional yam-forming processes such as carding and air-vortex spinning and nontraditional processes such as tape forming and wet casting. Carborundum additionally performed an economic analysis for producing 500 and 10,000 pounds of SiC fibrils annually using both conservative and more aggressive processing parameters. With the aggressive approach, the projected costs for SiC fibril production for 500 and 10,000 pounds per year are $1,340/pound and $340/pound, respectively.

  19. Defect Structure and Evolution in Silicon Carbide Irradiated to 1 dpa-SiC at 1100 C

    SciTech Connect (OSTI)

    D.J. Senor; G.E. Youngblood; L.R. Greenwood; D.V. Archer; D.L. Alexander; M.C. Chen; G.A. Newsome

    2002-05-13T23:59:59.000Z

    Transmission electron microscopy (TEM), swelling measurements, isochronal annealing, and thermal diffusivity testing were used to characterize the effects of radiation damage in SiC. Together, these techniques provided a comprehensive set of tools for observing and characterizing the structure and evolution of radiation-induced defects in SiC as a function of irradiation temperature and dose. In this study, two types of dense, crystalline, monolithic SiC were subjected to irradiation doses up to 1 dpa-SiC at a temperature of 1100 C, as well as post-irradiation annealing up to 1500 C. The microscopic defect structures observed by TEM were correlated to changes in the macroscopic dimensions, thermal diffusivity and thermal conductivity. The results demonstrated the value of using ultrapure {beta}SiC as an effective reference material to characterize the nature of expected radiation damage in other, more complex, SiC-based materials such as SiC/SiC composites.

  20. Engineering scale development of the Vapor-Liquid-Solid (VLS) process for the production of silicon carbide fibrils

    SciTech Connect (OSTI)

    Hollar, W.E. Jr. [Carborundum Co., Niagara Falls, NY (United States). Technology Div.; Mills, W.H. [BP America, Inc., Cleveland, OH (United States)

    1993-09-01T23:59:59.000Z

    Vapor-liquid-solid (VLS)SiC fibrils are used as reinforcement in ceramic matrix composites (CMC). A program has been completed for determining process scaleup parameters and to produce material for evaluation in a CMC. The scaleup is necessary to lower production cost and increase material availability. Scaleup parameters were evaluated in a reactor with a vertical dimension twice that of the LANL reactor. Results indicate that the scaleup will be possible. Feasibility of recycling process gas was demonstrated and the impact of postprocessing on yields determined.

  1. Engineering-scale development of the vapor-liquid-solid (VLS) process for the production of silicon carbide fibrils

    SciTech Connect (OSTI)

    Hollar, W.E. [Carborundum Company, Niagara Falls, NY (United States); Mills, W.H. [BP Research, Warrensville, OH (United States)

    1993-07-01T23:59:59.000Z

    The Phase 1 portion of the development program has been completed. Under this program the following milestones were achieved: (1) successful transfer of the Los Alamos National Laboratory process technology to Carborundum, (2) evaluation of key fibril synthesis scaleup parameters, (3) development of a computer model which simulates reactor performance, (4) development of a process gas recycle system, (5) evaluation of beneficiation processes for fibrils of various lengths. Significant results and conclusions from this program are discussed. VLS SiC fibrils will be used as a reinforcement in ceramic matrix composite (CMC) applications. The long length of the fibrils relative to standard SiC whisker materials could allow the fibrils to behave similarly to continuous fibers. This, combined with the excellent thermal and mechanical properties of the VLS SiC fibril, could lead to high-temperature ceramic matrix composites based on the fibril. A manufacturing process for converting the fibrils into well-aligned, high-volume fraction yarns will be required to achieve this goal. Fibril characteristics and potential process concepts for successful yarn forming are discussed.

  2. The role of oxygen in hydrogen sensing by a platinum-gate silicon carbide gas sensor: An ultrahigh vacuum study

    E-Print Network [OSTI]

    Ghosh, Ruby N.

    steering for advanced laser interferometer gravitational wave observatory sensing and control signals Rev of fundamental mechanisms has been less extensive.23­25 Reference 26 presents a model of the hydrogen

  3. Atomically flat La-silicate/Si interface using tungsten carbide gate electrode with nano-sized grain

    SciTech Connect (OSTI)

    Tuokedaerhan, K.; Natori, K.; Iwai, H. [Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Kakushima, K., E-mail: kakushima@ep.titech.ac.jp; Kataoka, Y.; Nishiyama, A.; Sugii, N.; Wakabayashi, H.; Tsutsui, K. [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

    2014-01-13T23:59:59.000Z

    Interface properties of La-silicate gate dielectrics on Si substrates with W or nano-sized grain W{sub 2}C gate electrodes have been investigated. A low interface state density of 2.5?×?10{sup 11}?cm{sup ?2}/eV has been achieved with W{sub 2}C gate electrodes, which is one third of those with W gate electrode. An interface roughness of 0.33?nm with spatial frequency comparable to the grain size of W gate electrode has been observed. Besides, an atomically flat interface of 0.12?nm has been obtained with W{sub 2}C gate electrode. The origin of flat interface may be attributed to the elimination of inhomogeneous stress by grains in metal electrode.

  4. Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride, carbide and carbonitride

    DOE Patents [OSTI]

    Wong, M.S.; Li, D.; Chung, Y.W.; Sproul, W.D.; Chu, X.; Barnett, S.A.

    1998-07-07T23:59:59.000Z

    A composite material having high hardness comprises a carbon nitrogen compound, such as CN{sub x} where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN{sub x}. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45--55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating. 10 figs.

  5. Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride, carbide and carbonitride

    DOE Patents [OSTI]

    Wong, Ming-Show (Northbrook, IL); Li, Dong (Evanston, IL); Chung, Yip-Wah (Wilmette, IL); Sproul, William D. (Palantine, IL); Chu, Xi (Evanston, IL); Barnett, Scott A. (Evanston, IL)

    1998-01-01T23:59:59.000Z

    A composite material having high hardness comprises a carbon nitrogen compound, such as CN.sub.x where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN.sub.x. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45-55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating.

  6. Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride carbide and carbonitride

    DOE Patents [OSTI]

    Wong, M.S.; Li, D.; Chung, Y.W.; Sproul, W.D.; Xi Chu; Barnett, S.A.

    1998-03-10T23:59:59.000Z

    A composite material having high hardness comprises a carbon nitrogen compound, such as CN{sub x} where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN{sub x}. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45--55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating. 10 figs.

  7. Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride carbide and carbonitride

    DOE Patents [OSTI]

    Wong, Ming-Show (Northbrook, IL); Li, Dong (Evanston, IL); Chung, Yin-Wah (Wilmette, IL); Sproul, William D. (Palantine, IL); Chu, Xi (Evanston, IL); Barnett, Scott A. (Evanston, IL)

    1998-01-01T23:59:59.000Z

    A composite material having high hardness comprises a carbon nitrogen compound, such as CN.sub.x where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN.sub.x. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45-55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating.

  8. Improvement of pin-type amorphous silicon solar cell performance by employing double silicon-carbide p-layer structure

    E-Print Network [OSTI]

    Kim, Yong Jung

    structure, and slow deposition rate improves the open-circuit voltage (Voc), short-circuit current density- proves the FF, as well as considerably enhances Voc and the short-circuit current density (Jsc). Thus through use of this buffer layer, the open-circuit voltage (Voc) and short-wavelength response could

  9. Characterization of new Co and Ru on -WC catalysts for Fischer-Tropsch reaction. Influence of the carbide surface state.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Characterization of new Co and Ru on -WC catalysts for Fischer-Tropsch reaction. Influence.griboval@univ-lille1.fr Abstract An investigation of the performances in Fischer-Tropsch reaction of 1wt% M/WC(X) (M of this natural gas induces a renewed interest for the Fischer-Tropsch reaction which is one of the major routes

  10. Characterization of new Co and Ru on -WC catalysts for Fischer-Tropsch reaction. Influence of the carbide surface state.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Characterization of new Co and Ru on -WC catalysts for Fischer-Tropsch reaction. Influence.griboval@univ-lille1.fr Abstract An investigation of the performances in Fischer-Tropsch reaction of 1wt% M/WC(X) (M wild resources crude oil. Valorization of this natural gas induces a renewed interest for the Fischer-Tropsch

  11. X-ray line broadening studies on aluminum nitride, titanium carbide and titanium diboride modified by high pressure shock loading

    SciTech Connect (OSTI)

    Morosin, B.; Graham, R.A.

    1983-01-01T23:59:59.000Z

    Powders of AlN, TiC and TiB/sub 2/ have been subjected to controlled shock loading with peak pressures in the samples between 14 to 27 GPa and preserved for post-shock study. Broadened x-ray diffraction peak profiles are analyzed by a simplified method and show increases in residual lattice strain and small decreases in crystallite size. Strain values range from 10/sup -5/ to 10/sup -4/ for TiB/sub 2/ and to values larger than 10/sup -3/ for TiC and AlN.

  12. Solid-particle erosion of tungsten carbide/cobalt cermet vs. hardened AISI 440C stainless steel.

    SciTech Connect (OSTI)

    Rateick, R. G., Jr.; Karasek, K. R.; Cunningham, A.; Goretta, K. C.; Routbort, J. L.; Energy Technology; Honeywell

    2006-01-01T23:59:59.000Z

    Solid-particle erosion tests were conducted on hardened AISI 440C stainless steel and a cermet that consisted of {approx}90 vol.% submicrometer WC embedded in {approx}10 vol.% Co. Angular Al{sub 2}O{sub 3} abrasives were used as the erodent. Experimental variables were: angle of impact = 20, 50, or 90 degrees; erodent velocity = 60 or 120 m/s; erodent nominal diameter = 63 or 143 {micro}m. For all test conditions, the stainless steel eroded faster than the cermet. Analysis of weight-loss data and examination of eroded surfaces by scanning electron microscopy indicated that the erosion mechanisms were similar for the two hard materials. Both exhibited significant plasticity when impacted, but the stainless steel's response to impact appeared to have been more ductile in nature.

  13. EIS-0132: Remedial Actions at the Former Union Carbide Corp. Uranium Mill Sites, Rifle, Garfield County, Colorado

    Broader source: Energy.gov [DOE]

    The U.S. Department of Energy developed this statement to evaluate and compare the environmental impacts of remediating the residual radioactive materials left at the inactive uranium tailing sites in Rifle, Colorado.

  14. Vector drop-on-demand production of tungsten carbide-cobalt tooling inserts by three dimensional printing

    E-Print Network [OSTI]

    Guo, David, 1976-

    2004-01-01T23:59:59.000Z

    Three Dimensional Printing (3DP) is a solid freeform fabrication process used to generate solid parts directly from three-dimensional computer models. A part geometry is created by selectively depositing binder into ...

  15. By Earle B. Amey Tungsten's unique high-temperature in Metal Bulletin (London). ferrotungsten, carbide powder blends, and

    E-Print Network [OSTI]

    of a stronger tungsten market, at certain forms of waste and scrap. production of numerous end-use items of the U.S. economy influenced the overall increase in demand for tungsten products during 1994. The antidumping tariffs on imports of tungsten ore concentrates and products from China, initially imposed

  16. Low resistance barrier layer for isolating, adhering, and passivating copper metal in semiconductor fabrication

    DOE Patents [OSTI]

    Weihs, Timothy P. (Baltimore, MD); Barbee, Jr., Troy W. (Palto Alto, CA)

    2002-01-01T23:59:59.000Z

    Cubic or metastable cubic refractory metal carbides act as barrier layers to isolate, adhere, and passivate copper in semiconductor fabrication. One or more barrier layers of the metal carbide are deposited in conjunction with copper metallizations to form a multilayer characterized by a cubic crystal structure with a strong (100) texture. Suitable barrier layer materials include refractory transition metal carbides such as vanadium carbide (VC), niobium carbide (NbC), tantalum carbide (TaC), chromium carbide (Cr.sub.3 C.sub.2), tungsten carbide (WC), and molybdenum carbide (MoC).

  17. Method for forming a barrier layer

    DOE Patents [OSTI]

    Weihs, Timothy P. (Baltimore, MD); Barbee, Jr., Troy W. (Palo Alto, CA)

    2002-01-01T23:59:59.000Z

    Cubic or metastable cubic refractory metal carbides act as barrier layers to isolate, adhere, and passivate copper in semiconductor fabrication. One or more barrier layers of the metal carbide are deposited in conjunction with copper metallizations to form a multilayer characterized by a cubic crystal structure with a strong (100) texture. Suitable barrier layer materials include refractory transition metal carbides such as vanadium carbide (VC), niobium carbide (NbC), tantalum carbide (TaC), chromium carbide (Cr.sub.3 C.sub.2), tungsten carbide (WC), and molybdenum carbide (MoC).

  18. Energy Savings and Green Initiatives Project Grant

    SciTech Connect (OSTI)

    Kathy MacLennan

    2011-11-21T23:59:59.000Z

    This project entails retrofitting all four foot, 2, 3 and 4 bulb 40 watt T12 fixtures to T8 28 watt and 150 watt incandescent to 26 watt compact fluorescent bulbs. In total, 2,086 fixtures will be retrofitted

  19. Composite of refractory material

    DOE Patents [OSTI]

    Holcombe, Cressie E. (Knoxville, TN); Morrow, Marvin S. (Kingston, TN)

    1994-01-01T23:59:59.000Z

    A composite refractory material composition comprises a boron carbide matrix and minor constituents of yttrium-boron-oxygen-carbon phases uniformly distributed throughout the boron carbide matrix.

  20. EC RESEARCH AND DEVELOPMENT REPORT .:'

    Office of Legacy Management (LM)

    Union Carbide Nuclear Company (ORNL) Union Carbide Nuclear Company (Paducah Plant) University of California, Berkeley Technical Information Service Extension WIN-115...

  1. Composite of refractory material

    DOE Patents [OSTI]

    Holcombe, C.E.; Morrow, M.S.

    1994-07-19T23:59:59.000Z

    A composite refractory material composition comprises a boron carbide matrix and minor constituents of yttrium-boron-oxygen-carbon phases uniformly distributed throughout the boron carbide matrix.

  2. Al2O3 ADHERENCE ON CoCrAl ALLOYS

    E-Print Network [OSTI]

    Kingsley, L.M.

    2010-01-01T23:59:59.000Z

    in a one percent aluminum alloy. After an aluminizing treat­oxidation, most alloys contained enough aluminum to preventof a dilute Co-Cr alloy with no aluminum or hafnium, and

  3. Early transitional metal alkyl, alkylidene, and alkylidyne chemistry

    E-Print Network [OSTI]

    Tonzetich, Zachary John

    2007-01-01T23:59:59.000Z

    CHAPTER 1. Zirconium and hafnium complexes of several new unsymmetric diamide ligands have been prepared and their proficiency in olefin polymerization reactions evaluated. The first set of supporting ligands examined are ...

  4. Nickel aluminides and nickel-iron aluminides for use in oxidizing environments

    DOE Patents [OSTI]

    Liu, Chain T. (Oak Ridge, TN)

    1988-03-15T23:59:59.000Z

    Nickel aluminides and nickel-iron aluminides treated with hafnium or zirconium, boron and cerium to which have been added chromium to significantly improve high temperature ductility, creep resistance and oxidation properties in oxidizing environments.

  5. Micro/nano devices fabricated from Cu-Hf thin films

    DOE Patents [OSTI]

    Luber, Erik J; Ophus, Colin; Mitlin, David; Olsen, Brian; Harrower, Christopher; Radmilovi, Velimir

    2013-06-04T23:59:59.000Z

    An all-metal microdevice or nanodevice such as an atomic force microscope probe is manufactured from a copper-hafnium alloy thin film having an x-ray amorphous microstructure.

  6. Characteristics of Hf-silicate thin films synthesized by plasma enhanced atomic layer deposition

    SciTech Connect (OSTI)

    Liu Jiurong; Martin, Ryan M.; Chang, Jane P. [Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095 (United States)

    2008-09-15T23:59:59.000Z

    Hafnium silicate films were grown by alternating the deposition cycles of hafnium oxide and silicon oxide using a plasma enhanced atomic layer deposition process. The as-deposited and 900 deg. C annealed hafnium silicate films were determined to be amorphous using grazing incidence x-ray diffraction. This suggested that the formation of hafnium silicate suppressed the crystallization of HfO{sub 2} at high temperatures. The dielectric constants increased from {approx}5 to {approx}17 as the hafnium content increased from 9 to 17 at. % in the hafnium silicate films. The leakage currents through the Hf-rich Hf-silicate films were two to three orders of magnitude lower than that of SiO{sub 2} with the same equivalent oxide thickness in the range of 1.6-2.3 nm. The estimated band gap of Hf-silicate films from the O 1s plasma loss spectra increased with the increasing Si content due to the higher band gap of SiO{sub 2} than that of HfO{sub 2}.

  7. Optical Semiconductor DevicesOptical Semiconductor Devices The Foundations of the Laser Diode

    E-Print Network [OSTI]

    La Rosa, Andres H.

    Glowing DiodeThe Glowing Diode ·· ""LuminousLuminous carborundum [siliconcarborundum [silicon carbide

  8. Department of Ecosystem Science & SOIL RESEARCH CLUSTER LABORATORY

    E-Print Network [OSTI]

    Boyer, Elizabeth W.

    , Organometallics, Gasoline and fuels, Coal and coke, Graphite and carbides, Metals and alloys · Operator: Julie

  9. Development and testing of radiation and electromagnetic pulse-hardened silicon carbide-based electronics. Quarterly report, 1 Dec 90-28 Feb 91

    SciTech Connect (OSTI)

    Edmond, J.A.; Palmour, J.W.

    1991-04-30T23:59:59.000Z

    There were three primary objectives for this reporting period. The first was to electrically characterize junction diodes as a function of temperature. This included both current-voltage (I-V) and capacitance-voltage (C-V) measurements. The second was to fabricate low (about 125 V) and medium (about 450 V) voltage p-n junction rectifiers for neutron and gamma exposure tests. The third objective was to fabricate JFET devices with reduced gate and drain leakage currents than those discussed in the previous report and to package these devices in preparation for radiation testing.

  10. Engineering scale development of the vapor-liquid-solid (VLS) process for the production of silicon carbide fibrils and linear fibril assemblies

    SciTech Connect (OSTI)

    Tenhover, M.; Biernacki, J. [Carborundum Co., Niagara Falls, NY (United States); Schatz, K.; Ko, F. [Advanced Product Development, Inc., Bristol, PA (United States)

    1995-08-01T23:59:59.000Z

    In order to exploit the superior thermomechanical properties of the VLS fibril, the feasibility of scaled-up production of the SiC fibril is demonstrated in this study. Through time series study and computer simulation, the parameters affecting the growth process and properties of the fibrils were examined. To facilitate translation of the superior mechanical properties into higher level preform structures, conventional and unconventional processing methods were evaluated. As revealed by scanning electron microscopic examination and X-ray diffractometry, high level alignment of the fibrils was achieved by the wet-laid process.

  11. Comparison of reactive magnesia-, carbide slag-activated ground granulated blastfurnace slag and Portland cement for stabilisation of a natural soil

    E-Print Network [OSTI]

    Yi, Yaolin; Zheng, Xu; Liu, Songyu; Al-Tabbaa, Abir

    2015-04-11T23:59:59.000Z

    -95%) and CaCO3 (1-10%) (Cardoso et al., 2009). Currently, most of the CS in China is landfilled; however, CS has the potential to replace hydrated lime to activate GGBS for soil stabilisation due to their similar chemical compositions. Recently, reactive... from Nanjing Iron & Steel Group Corp., Weisheng Gas Co. Ltd and Yuhua Cement Co. Ltd, respectively. The chemical composition of the soil and binder materials was determined by X-ray fluorescence spectrometer (ARL9800 XP, The Thermo Scientific...

  12. The carburization of transition metal molybdates (MxMoO?, M= Cu, Ni or Co) and the generation of highly active metal/carbide catalysts for CO? hydrogenation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rodriguez, Jose A.; Xu, Wenqian; Ramirez, Pedro J.; Stachiola, Dario; Brito, Joaquin L.

    2015-05-06T23:59:59.000Z

    A new approach has been tested for the preparation of metal/Mo?C catalysts using mixed-metal oxide molybdates as precursors. Synchrotron-based in situ time-resolved X-ray diffraction was used to study the reduction and carburization processes of Cu?(MoO?)?(OH)?, a-NiMoO? and CoMoO?•nH?O by thermal treatment under mixtures of hydrogen and methane. In all cases, the final product was ?-Mo?C and a metal phase (Cu, Ni, or Co), but the transition sequence varied with the different metals, and it could be related to the reduction potential of the Cu²?, Ni²? and Co²? cations inside each molybdate. The synthesized Cu/Mo?C, Ni/Mo?C and Co/Mo?C catalysts were highlymore »active for the hydrogenation of CO?. The metal/Mo?C systems exhibited large variations in the selectivity towards methanol, methane and CnH?n?? (n > 2) hydrocarbons depending on the nature of the supported metal and its ability to cleave C-O bonds. Cu/Mo?C displayed a high selectivity for CO and methanol production. Ni/Mo?C and Co/Mo?C were the most active catalysts for the activation and full decomposition of CO?, showing high selectivity for the production of methane (Ni case) and CnH?n?? (n > 2) hydrocarbons (Co case).« less

  13. Probing the mechanism of high capacitance in two-dimensional titanium carbide using in-situ X-Ray absorption spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lukatskaya, Maria R.; Bak, Seong -Min; Yu, Xiqian; Yang, Xiao -Qing; Barsoum, Michel W.; Gogotsi, Yury

    2015-05-01T23:59:59.000Z

    The field of supercapacitors (electrochemical capacitors) is constantly evolving. The global motivation is to create devices that possess a significant energy density without compromising the power density. To achieve this goal, new materials must be discovered and complex electrode architectures developed.

  14. The formation of PdCx over Pd-based catalysts in vapor-phase vinyl acetate synthesis: does a PdAu alloy catalyst resist carbide formation?

    E-Print Network [OSTI]

    Goodman, Wayne

    a Pd­Au/SiO2 mixed-metal catalyst. XRD data show that PdCx was produced in the pure Pd catalysts after greater resistance to the formation of PdCx. The XRD and XPS data are consistent with formation of a Pd in a micro-reactor using online GC; before reaction the catalysts were pretreated (oxidized in a 20 m

  15. Analysis of system wide distortion in an integrated power system utilizing a high voltage DC bus and silicon carbide power devices

    E-Print Network [OSTI]

    Fallier, William F. (William Frederick)

    2007-01-01T23:59:59.000Z

    This research investigates the distortion on the electrical distribution system for a high voltage DC Integrated Power System (IPS). The analysis was concentrated on the power supplied to a propulsion motor driven by an ...

  16. The carburization of transition metal molybdates (MxMoO?, M= Cu, Ni or Co) and the generation of highly active metal/carbide catalysts for CO? hydrogenation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rodriguez, Jose A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Xu, Wenqian [Brookhaven National Lab. (BNL), Upton, NY (United States); Ramirez, Pedro J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Univ. Central De Venezuela, Caracas (Venesuela); Stachiola, Dario [Brookhaven National Lab. (BNL), Upton, NY (United States); Brito, Joaquin L. [Inst. Venezolano de Investigaciones Cientificas, Caracas (Venezuela)

    2015-05-06T23:59:59.000Z

    A new approach has been tested for the preparation of metal/Mo?C catalysts using mixed-metal oxide molybdates as precursors. Synchrotron-based in situ time-resolved X-ray diffraction was used to study the reduction and carburization processes of Cu?(MoO?)?(OH)?, a-NiMoO? and CoMoO?•nH?O by thermal treatment under mixtures of hydrogen and methane. In all cases, the final product was ?-Mo?C and a metal phase (Cu, Ni, or Co), but the transition sequence varied with the different metals, and it could be related to the reduction potential of the Cu²?, Ni²? and Co²? cations inside each molybdate. The synthesized Cu/Mo?C, Ni/Mo?C and Co/Mo?C catalysts were highly active for the hydrogenation of CO?. The metal/Mo?C systems exhibited large variations in the selectivity towards methanol, methane and CnH?n?? (n > 2) hydrocarbons depending on the nature of the supported metal and its ability to cleave C-O bonds. Cu/Mo?C displayed a high selectivity for CO and methanol production. Ni/Mo?C and Co/Mo?C were the most active catalysts for the activation and full decomposition of CO?, showing high selectivity for the production of methane (Ni case) and CnH?n?? (n > 2) hydrocarbons (Co case).

  17. Electronic structure of the 4d transition metal carbides: Dispersed fluorescence spectroscopy of MoC, RuC, and PdC

    E-Print Network [OSTI]

    Morse, Michael D.

    C, RuC, and PdC Ryan S. DaBell,a) Raymond G. Meyer,b) and Michael D. Morsec) Department of Chemistry fluorescence studies of the diatomic molecules MoC, RuC, and PdC are reported. New states identified in Mo are observed by dispersed fluorescence in PdC. The ground state is found to be ... 2 4 12 2 , 1

  18. Method for fabricating hafnia films

    DOE Patents [OSTI]

    Hu, Michael Z [Knoxville, TN

    2007-08-21T23:59:59.000Z

    The present invention comprises a method for fabricating hafnia film comprising the steps of providing a substrate having a surface that allows formation of a self-assembled monolayer thereon via covalent bonding; providing an aqueous solution that provides homogeneous hafnium ionic complexes and hafnium nanoclusters wherein the aqueous solution is capable of undergoing homogeneous precipitation under controlled conditions for a desired period of time at a controlled temperature and controlled solution acidity for desired nanocluster nucleation and growth kinetics, desired nanocluster size, desired growth rate of film thickness and desired film surface characteristics. The method further comprising forming the self-assembled monolayer on the surface of the substrate wherein the self-assembled monolayer comprises a plurality of hydrocarbon chains cross-linked together along the surface of the substrate, the hydrocarbon chains being uniformly spaced from one another and wherein each of the hydrocarbon chains having a functional anchoring group at a first end of the chain covalently bonded with the surface of the substrate and each of the hydrocarbon chains having a functional terminating group projected away from the surface wherein the functional terminating group provides a bonding site for the hafnium film to grow; and exposing the substrate to the aqueous solution for a desired period of time at a controlled temperature wherein the hafnium ionic complexes and the hafnium nanoclusters are deposited on the bonding site of the functional terminating group thereby forming the hafnia film wherein the hafnium bonded to the hydrocarbons and to one another provide a uniform ordered arrangement defined by the uniform arrangement of the hydrocarbons.

  19. anaerobic ultramicrobacteria belonging: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Hugh's son. Silicon Carbide Specimen This specimen of silicon carbide, also known as carborundum or moissanite, was produced in an electric batch furnace at NC State College in the...

  20. antagonistic bacterium belonging: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Hugh's son. Silicon Carbide Specimen This specimen of silicon carbide, also known as carborundum or moissanite, was produced in an electric batch furnace at NC State College in the...

  1. The effect of inhibitors on material and mechanical properties of oxidized carbon-carbon composites 

    E-Print Network [OSTI]

    Elliott, Charles Howard

    1995-01-01T23:59:59.000Z

    The carbon-carbon laminates examined in this research program are two-dimensional, eight harness satin weaves with boron carbide (B4C) inhibitor particles and a multi-layer silicon carbide (SiC) coating. These inhibitor ...

  2. Acknowledgements: Special thanks are due for assistance from the Bhopal Group for

    E-Print Network [OSTI]

    Johnston P. A; Stan Vincent; Shailendra Yashwant

    1999-01-01T23:59:59.000Z

    Victims of the Union Carbide disaster attend a weekly meeting. c Greenpeace/YashwantToxic contaminants at the former Union Carbide factory site, Bhopal, India: 15 years after the Bhopal accident.

  3. anisotropic gas diffusion: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    2014 Keywords: Low-temperature combustion syn- thesis Tungsten carbide Electrocatalyst Gas diffusion electrode a b s t r a c t Tungsten carbide powder, which is used as the...

  4. Uranium Mill Tailings Remedial Action Project (UMTRAP), Slick Rock, Colorado, Revision 1. Volume 1, Calculations, Final design for construction

    SciTech Connect (OSTI)

    NONE

    1995-09-01T23:59:59.000Z

    Volume one contains calculations for: embankment design--embankment material properties; Union Carbide site--bedrock contours; vicinity properties--origin of contamination; North Continent and Union Carbide sites contaminated materials--excavation quantities; and demolition debris--quantity estimate.

  5. Thickness independent reduced forming voltage in oxygen engineered HfO{sub 2} based resistive switching memories

    SciTech Connect (OSTI)

    Sharath, S. U., E-mail: sharath@oxide.tu-darmstadt.de; Kurian, J.; Komissinskiy, P.; Hildebrandt, E.; Alff, L. [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Bertaud, T.; Walczyk, C.; Calka, P. [IHP, Im Technologiepark 25, 15236 Frankfurt Oder (Germany); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt Oder (Germany); Brandenburgische Technische Universität, Konrad-Zuse-Strasse 1, 03046 Cottbus (Germany)

    2014-08-18T23:59:59.000Z

    The conducting filament forming voltage of stoichiometric hafnium oxide based resistive switching layers increases linearly with layer thickness. Using strongly reduced oxygen deficient hafnium oxide thin films grown on polycrystalline TiN/Si(001) substrates, the thickness dependence of the forming voltage is strongly suppressed. Instead, an almost constant forming voltage of about 3?V is observed up to 200?nm layer thickness. This effect suggests that filament formation and switching occurs for all samples in an oxidized HfO{sub 2} surface layer of a few nanometer thickness while the highly oxygen deficient thin film itself merely serves as a oxygen vacancy reservoir.

  6. E-Print Network 3.0 - alkali metal oxides Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    , sodium carbide, turpentine, finely divided metals Calcium water, carbon dioxide, carbon tetrachloride... , and chlorinated hydrocarbons Carbon, activated calcium...

  7. THE EFFECT OF AIR-COOLING HEAT TREATMENTS ON THE STRUCTURE AND PROPERTIES OF Fe/4Cr/ 0.3C/2Mn ALLOY

    E-Print Network [OSTI]

    Rabe, T.H.

    2010-01-01T23:59:59.000Z

    high temperature (1100°-1150°C) to dissolve carbide structures entirely and then quickly cooled (hot water

  8. Assessment of China's Energy-Saving and Emission-Reduction Accomplishments and Opportunities During the 11th Five Year Plan

    E-Print Network [OSTI]

    Levine, Mark D.

    2010-01-01T23:59:59.000Z

    calcium carbide, coking, cement, coal, plate glass, pulp andcarbide 2 Mt Coking 80 Mt Cement 250 Mt Coal mining (

  9. Synthesis of nanocrystalline aluminum matrix composites reinforced with in situ devitrified Al-Ni-La amorphous particles

    E-Print Network [OSTI]

    Zhang, Zhihui H; Han, B Q; Witkin, D; Ajdelsztajn, L; Laverna, E J

    2006-01-01T23:59:59.000Z

    of nanocrystalline aluminum matrix composites reinforcedAbstract Nanocrystalline aluminum matrix composites wereamount of nanoscale aluminum oxide, nitride and carbide

  10. Electronic Transitions of CsC2, CsC2 -, and CsC4 in Neon Matrixes

    E-Print Network [OSTI]

    Maier, John Paul

    of the bulk metal carbides (e.g., ZrC has one of the highest melting points among known materials), laser by sputtering a graphite surface with Cs+ were mass-selected and trapped in neon matrixes at 6 K. The electronic of transition-metal carbides,22-24 lanthanide carbides,25 and Al2C2 -26 produced by laser ablation

  11. Above: On-axis field profiles of resistive, superconducting and all magnets, and bore-tube radius r = 7.5 (B/20T)- cm.

    E-Print Network [OSTI]

    McDonald, Kirk

    MAGNET SYSTEM FOR A MUON COLLIDER AND NEUTRINO FACTORY (TUPS053, IPAC11) The concept for a muon-production filled with tungsten-carbide pellets (~ 60% by volume, cooled by water) attenuate the radiation issuing.4 MW Superconducting magnets tungsten-carbide (WC) beads + water tungsten-carbide beads + water proton

  12. Production method for making rare earth compounds

    DOE Patents [OSTI]

    McCallum, R. William (Ames, IA); Ellis, Timothy W. (Ames, IA); Dennis, Kevin W. (Ames, IA); Hofer, Robert J. (Ames, IA); Branagan, Daniel J. (Ames, IA)

    1997-11-25T23:59:59.000Z

    A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g. a transition metal and optional boron), and a carbide-forming element (e.g. a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g. Nd.sub.2 Fe.sub.14 B or LaNi.sub.5) and a carbide of the carbide-forming element are formed.

  13. Production method for making rare earth compounds

    DOE Patents [OSTI]

    McCallum, R.W.; Ellis, T.W.; Dennis, K.W.; Hofer, R.J.; Branagan, D.J.

    1997-11-25T23:59:59.000Z

    A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g., a transition metal and optional boron), and a carbide-forming element (e.g., a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g., Nd{sub 2}Fe{sub 14}B or LaNi{sub 5}) and a carbide of the carbide-forming element are formed.

  14. Boron containing multilayer coatings and method of fabrication

    DOE Patents [OSTI]

    Makowiecki, Daniel M. (Livermore, CA); Jankowski, Alan F. (Livermore, CA)

    1997-01-01T23:59:59.000Z

    Hard coatings are fabricated from multilayer boron/boron carbide, boron carbide/cubic boron nitride, and boron/boron nitride/boron carbide, and the fabrication thereof involves magnetron sputtering in a selected atmosphere. These hard coatings may be applied to tools and engine and other parts, as well to reduce wear on tribological surfaces and electronic devices. These boron coatings contain no morphological growth features. For example, the boron and boron carbide used in forming the multilayers are formed in an inert (e.g. argon) atmosphere, while the cubic boron nitride is formed in a reactive (e.g. nitrogen) atmosphere. The multilayer boron/boron carbide, and boron carbide/cubic boron nitride is produced by depositing alternate layers of boron, cubic boron nitride or boron carbide, with the alternate layers having a thickness of 1 nanometer to 1 micrometer, and at least the interfaces of the layers may be of a discrete or a blended or graded composition.

  15. 2011 Minerals Yearbook U.S. Department of the Interior

    E-Print Network [OSTI]

    2011 Minerals Yearbook U.S. Department of the Interior U.S. Geological Survey ZIRCONIUM AND HAFNIUM mineral concentrates in 2011, excluding U.S. production, was about 1.62 million metric tons (Mt) compared with 1.25 Mt in 2010. The primary source of zirconium was the mineral zircon (ZrSiO4 ), principally found

  16. ORNL 2010-G00656/jcn UT-B IDs 200701908, 200701909, 200701910

    E-Print Network [OSTI]

    Comprising Hydrous Aluminum Oxide, U.S. Patent Application 12/683,925, filed January 7, 2010. Lead Inventor, Cerium, or Aluminum Oxide Gels and Spherules Technology Summary An internal gelatin process for preparing hydrous hafnium, cerium, or aluminum oxide microspheres was invented at ORNL. The invention is a type

  17. U.S. Department of the Interior U.S. Geological Survey

    E-Print Network [OSTI]

    Torgersen, Christian

    Graphite Peat Talc Beryllium Gypsum Perlite Tantalum Bismuth Hafnium Phosphate Rock Tellurium Boron Helium information on the USGS--the Federal source for science about the Earth, its natural and living resources--Reserves and Resources.....................193 Appendix D--Country Specialists Directory...............198 Mineral

  18. Iron and Steel Phosphate Rock

    E-Print Network [OSTI]

    Torgersen, Christian

    Kyanite Lead Lime Lithium Magnesium Manganese Mercury Mica Molybdenum Nickel Nitrogen Peat Perlite Graphite Peat Sulfur Beryllium Gypsum Perlite Talc Bismuth Hafnium Phosphate Rock Tantalum Boron Helium information on the USGS--the Federal source for science about the Earth, its natural and living resources

  19. U.S. Department of the Interior U.S. Geological Survey

    E-Print Network [OSTI]

    Fleskes, Joe

    Graphite Peat Talc Beryllium Gypsum Perlite Tantalum Bismuth Hafnium Phosphate Rock Tellurium Boron Helium information on the USGS--the Federal source for science about the Earth, its natural and living resources--Reserves and Resources.....................193 Appendix D--Country Specialists Directory...............197 Mineral

  20. Isotopic tracing (Sr, Nd, U and Hf) of continental and marine aerosols in an 18th century section of the Dye-3 ice core (Greenland)

    E-Print Network [OSTI]

    Stocker, Thomas

    sea salts strontium neodymium hafnium uranium Determining the sources and pathways of atmospheric and 234 U/238 U activity ratios close to seawater. Nd variations are significant (N6 units) and are decoupled from dust composition, indicating that the Nd composition of seawater is preserved in the ice

  1. Reassessment of relative oxide formation rates and molecular interferences on in situ lutetiumhafnium

    E-Print Network [OSTI]

    Devernal, Anne

    ­hafnium analysis with laser ablation MC-ICP-MS Justin L. Payne,*a Norman J. Pearson,b Kevin J. Grantb and Galen P Hf at levels up to 176 Yb/177 Hf ¼ 0.6 in solution mode. When using laser ablation sample. Introduction A challenge to accurate and precise isotope ratio measurements by laser ablation multiple

  2. ORIGINAL PAPER Zircon Hf isotope perspective on the origin of granitic rocks

    E-Print Network [OSTI]

    Siebel, Wolfgang

    Ó Springer-Verlag 2009 Abstract The petrogenetic potential of in situ laser ablation Hf isotope data Bohemian Massif Á Granitoid Á Hafnium isotopes Á Laser ablation ICP-MS Á Variscan Á Zircon Introduction the Hf isotopic composition of individual zircons in situ by laser ablation ICP-MS (Thirlwall and Walder

  3. Trapping in deep defects under substrate hot electron stress in TiN/Hf-silicate based gate stacks

    E-Print Network [OSTI]

    Misra, Durgamadhab "Durga"

    Trapping in deep defects under substrate hot electron stress in TiN/Hf-silicate based gate stacks N. Zaslavsky Abstract Substrate hot electron stress was applied on n+ -ringed n-channel MOS capacitors with TiN/Hf-silicate. Introduction Hafnium silicate based high-j gate dielectrics have been put forth as the leading candidates

  4. 2010 Minerals Yearbook U.S. Department of the Interior

    E-Print Network [OSTI]

    subsidiary of Australian company Iluka Resources Ltd.). DuPont produced zircon from its heavy-mineral sands2010 Minerals Yearbook U.S. Department of the Interior U.S. Geological Survey ZIRCONIUM AND HAFNIUM. In 2010, the global economy began to recover, and consumption of zirconium ores and concentrates increased

  5. Iron and Steel Phosphate Rock

    E-Print Network [OSTI]

    Torgersen, Christian

    Phosphate Rock Platinum Potash Pumice Quartz Crystal Rare Earths Rhenium Rubidium Salt Sand and Gravel Graphite Peat Sulfur Beryllium Gypsum Perlite Talc Bismuth Hafnium Phosphate Rock Tantalum Boron Helium on the USGS--the Federal source for science about the Earth, its natural and living resources, natural hazards

  6. aluminium oxide thin: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the SiO2 or Si-OH layer on the Si(1 0 0) substrate led to the site-selectivity of oxide thin film growth Boo, Jin-Hyo 25 Sub-micron grating fabrication on hafnium oxide thin-film...

  7. 2007 Minerals Yearbook U.S. Department of the Interior

    E-Print Network [OSTI]

    .S. Geological Survey from a voluntary survey of domestic operations. Of the 44 operations surveyed, 32 did concentrates are developed by a second voluntary survey of domestic mining operations. Of the two domestic2007 Minerals Yearbook U.S. Department of the Interior U.S. Geological Survey ZIRCONIUM AND HAFNIUM

  8. 2008 Minerals Yearbook U.S. Department of the Interior

    E-Print Network [OSTI]

    of domestic operations. of the 46 operations surveyed, 21 responded. data for nonrespondents were estimated concentrates were developed from a second voluntary survey of domestic mining operations. The two domestic2008 Minerals Yearbook U.S. Department of the Interior U.S. Geological Survey ZIRCONIUM AND HAFNIUM

  9. 2009 Minerals Yearbook U.S. Department of the Interior

    E-Print Network [OSTI]

    a voluntary survey of domestic operations. of the 41 operations surveyed, 20 responded. data concentrates were developed from a second voluntary survey of domestic mining operations. The two domestic2009 Minerals Yearbook U.S. Department of the Interior U.S. Geological Survey ZIRCONIUM AND HAFNIUM

  10. High-K Based Non-Volatile Memory Devices with the Light Emitting Application

    E-Print Network [OSTI]

    Lin, Chi-Chou

    2014-09-05T23:59:59.000Z

    The zirconium-doped hafnium oxide (ZrHfO) high-k gate dielectric films with and without the embedded nanocrystals have been studied for the applications of the nonvolatile memory and light emitting devices. By replacing the polycrystalline Si...

  11. Microwave-assisted pyrolysis of SiC and its application to joining

    SciTech Connect (OSTI)

    Ahmad, I.; Silberglitt, R. [FM Technologies, Inc., Fairfax, VA (United States); Shan, T.A. [George Mason Univ., Fairfax, VA (United States)] [and others

    1995-07-01T23:59:59.000Z

    Microwave energy has been used to pyrolyze silicon carbide from commercially available polycarbosilane precursor. The pyrolysis was performed on SiC surfaces having various surface treatments, to identify conditions which improve the wetting and adherence. Grinding and etching of the surfaces in hydrofluoric (HF) acid promotes the bonding of precursor derived ceramic to the SiC ceramic. Finally, the polycarbosilane precursor mixed with fine silicon carbide powder was used as the interlayer material to join silicon carbide specimens.

  12. Zone sintering of ceramic fuels

    DOE Patents [OSTI]

    Matthews, R. Bruce (Falls Church, VA); Chidester, Kenneth M. (Los Alamos, NM); Moore, H. Gene (Los Alamos, NM)

    1994-01-01T23:59:59.000Z

    Cold pressed UC.sub.2 fuel compacts are sintered at temperatures greater than about 1850.degree. C. while in contact with a sintering facilitator material, e.g., tantalum, niobium, tungsten or a metal carbide such as uranium carbide, thereby allowing for a reduction in the overall porosity and leaving the desired product, i.e., a highly dense, large-grained uranium dicarbide. The process of using the sintering facilitator materials can be applied in the preparation of other carbide materials.

  13. Joining of materials using laser heating

    DOE Patents [OSTI]

    Cockeram, Brian V.; Hicks, Trevor G.; Schmid, Glenn C.

    2003-07-01T23:59:59.000Z

    A method for diffusion bonding ceramic layers such as boron carbide, zirconium carbide, or silicon carbide uses a defocused laser beam to heat and to join ceramics with the use of a thin metal foil insert. The metal foil preferably is rhenium, molybdenum or titanium. The rapid, intense heating of the ceramic/metal/ceramic sandwiches using the defocused laser beam results in diffusive conversion of the refractory metal foil into the ceramic and in turn creates a strong bond therein.

  14. High temperature superconductor/diamond composite article, and method of making the same

    SciTech Connect (OSTI)

    Beetz, C.P. Jr.; Kirlin, P.S.

    1992-06-16T23:59:59.000Z

    This patent describes a multilayer superconducting thin film composite article. It comprises a carbon-containing substrate; an interlayer comprising a material selected from the group consisting of: zirconium; yttrium; niobium; zirconium carbide; yttrium carbide; niobium carbide; zirconium oxide; yttrium oxide; niobium oxide; platinum; iridium; gold; silver; palladium; and combinations of two or more of the foregoing materials; and an overlayer comprising a HTSC material.

  15. Simulation and analysis of particle-aided CVD

    SciTech Connect (OSTI)

    NONE

    1996-02-01T23:59:59.000Z

    This report describes particle-aided chemical vapor deposition. It is the goal to produce various composites of silicon carbides and to theoretically analyze the process.

  16. advanced fuel performance: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    for fuel cell 2 Silicon carbide performance as cladding for advanced uranium and thorium fuels for light water reactors MIT - DSpace Summary: There has been an ongoing...

  17. QUANTITATIVE STUDIES OF THERMAL SHOCK IN CERAMICS BASED ON A NOVEL TEST TECHNIQUE

    E-Print Network [OSTI]

    Faber, K.T.

    2013-01-01T23:59:59.000Z

    Silicon Carbide Division The Carborundum Co. Niagara Falls,of this research provided by the Carborundum Co. (K.T.F. and

  18. Vehicle Technologies Office Merit Review 2015: 88 Kilowatt Automotive...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    88 Kilowatt Automotive Inverter with New 900 Volt Silicon Carbide MOSFET Technology Vehicle Technologies Office Merit Review 2015: 88 Kilowatt Automotive Inverter with New 900 Volt...

  19. antireflection coating design: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    (OHNS) steel finding many applications in Manufacturing parts like Shaft, Gears and Tooling due to their excellent Mechanical properties. The continuous development of carbide...

  20. atomic spectrometric methods: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    spectrometric, and spectrochemical analysis of nuclear-grade boron carbide powder and pellets to determine compliance with specifications. 1.2 The analytical procedures appear in...

  1. absorption spectrometric method: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    spectrometric, and spectrochemical analysis of nuclear-grade boron carbide powder and pellets to determine compliance with specifications. 1.2 The analytical procedures appear in...

  2. Energy Blog | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    a Silicon Carbide (SIC) transistor which can be used to create solid state transformers capable of meeting the unique needs of the emerging smart grid. February 28, 2013...

  3. activated carbon composites: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    T300: C strength 4340 steel, carbon-carbon composite, and Carbon-Silicon Carbide composite were tested to examine materials. MATERIALS AND DESIRED DATA Carbon-Carbon...

  4. ammonium carbonates: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    T300: C strength 4340 steel, carbon-carbon composite, and Carbon-Silicon Carbide composite were tested to examine materials. MATERIALS AND DESIRED DATA Carbon-Carbon...

  5. Dispersion toughened ceramic composites and method for making same

    DOE Patents [OSTI]

    Stinton, D.P.; Lackey, W.J.; Lauf, R.J.

    1984-09-28T23:59:59.000Z

    Ceramic composites exhibiting increased fracture toughness are produced by the simultaneous codeposition of silicon carbide and titanium disilicide by chemical vapor deposition. A mixture of hydrogen, methyltrichlorosilane and titanium tetrachloride is introduced into a furnace containing a substrate such as graphite or silicon carbide. The thermal decomposition of the methyltrichlorosilane provides a silicon carbide matrix phase and the decomposition of the titanium tetrachloride provides a uniformly dispersed second phase of the intermetallic titanium disilicide within the matrix phase. The fracture toughness of the ceramic composite is in the range of about 6.5 to 7.0 MPa..sqrt..m which represents a significant increase over that of silicon carbide.

  6. a537 carbon steel: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    T300: C strength 4340 steel, carbon-carbon composite, and Carbon-Silicon Carbide composite were tested to examine materials. MATERIALS AND DESIRED DATA Carbon-Carbon...

  7. americium carbonates: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    T300: C strength 4340 steel, carbon-carbon composite, and Carbon-Silicon Carbide composite were tested to examine materials. MATERIALS AND DESIRED DATA Carbon-Carbon...

  8. affecting carbon tetrachloride: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    T300: C strength 4340 steel, carbon-carbon composite, and Carbon-Silicon Carbide composite were tested to examine materials. MATERIALS AND DESIRED DATA Carbon-Carbon...

  9. Bio-inspired tailored hydroxyapatite-based powder composites for dental applications

    E-Print Network [OSTI]

    Lin, Yen-Shan

    2012-01-01T23:59:59.000Z

    prepared by spark plasma sintering process. Micropor.E. A. Olevsky. “Spark plasma sintering of tantalum carbide”pressureless spark-plasma sintering”, Advance in Applied

  10. Tetrides and Pnictides for Fast-Ion Conductors, Phosphor-Hosts, Structural Materials and Improved Thermoelectrics

    E-Print Network [OSTI]

    Hick, Sandra Marie

    2013-01-01T23:59:59.000Z

    Synthesis of Lanthanide Doped Nitride Phosphors. in UC Inorganic MaterialsSynthesis of Alkaline Earth Carbides and Intercalation Compounds. in Florida Inorganic & Materials

  11. 2003 Peered Reviewed Archival Publications Chemical Engineering

    E-Print Network [OSTI]

    Mohaghegh, Shahab

    for methane reforming with carbon dioxide over a mixed-metal carbide catalyst. I&EC Research 42: 2712-2721. Li

  12. UO

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    success in this work will deepen our fundamental understanding of the nuclear energy materials. Background: The actinide (U, Np, Pu) oxides, nitrides, and carbides are of...

  13. Metal matrix composite of an iron aluminide and ceramic particles and method thereof

    DOE Patents [OSTI]

    Schneibel, J.H.

    1997-06-10T23:59:59.000Z

    A metal matrix composite comprising an iron aluminide binder phase and a ceramic particulate phase such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide is made by heating a mixture of iron aluminide powder and particulates of one of the ceramics such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide in a alumina crucible at about 1,450 C for about 15 minutes in an evacuated furnace and cooling the mixture to room temperature. The ceramic particulates comprise greater than 40 volume percent to about 99 volume percent of the metal matrix composite.

  14. Metal matrix composite of an iron aluminide and ceramic particles and method thereof

    DOE Patents [OSTI]

    Schneibel, Joachim H. (Maryville, TN)

    1997-01-01T23:59:59.000Z

    A metal matrix composite comprising an iron aluminide binder phase and a ceramic particulate phase such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide is made by heating a mixture of iron aluminide powder and particulates of one of the ceramics such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide in a alumina crucible at about 1450.degree. C. for about 15 minutes in an evacuated furnace and cooling the mixture to room temperature. The ceramic particulates comprise greater than 40 volume percent to about 99 volume percent of the metal matrix composite.

  15. Dispersion toughened ceramic composites and method for making same

    DOE Patents [OSTI]

    Stinton, David P. (Knoxville, TN); Lackey, Walter J. (Oak Ridge, TN); Lauf, Robert J. (Oak Ridge, TN)

    1986-01-01T23:59:59.000Z

    Ceramic composites exhibiting increased fracture toughness are produced by the simultaneous codeposition of silicon carbide and titanium disilicide by chemical vapor deposition. A mixture of hydrogen, methyltrichlorosilane and titanium tetrachloride is introduced into a furnace containing a substrate such as graphite or silicon carbide. The thermal decomposition of the methyltrichlorosilane provides a silicon carbide matrix phase and the decomposition of the titanium tetrachloride provides a uniformly dispersed second phase of the intermetallic titanium disilicide within the matrix phase. The fracture toughness of the ceramic composite is in the range of about 6.5 to 7.0 MPa.sqroot.m which represents a significant increase over that of silicon carbide.

  16. Tetrides and Pnictides for Fast-Ion Conductors, Phosphor-Hosts, Structural Materials and Improved Thermoelectrics

    E-Print Network [OSTI]

    Hick, Sandra Marie

    2013-01-01T23:59:59.000Z

    Binder, and B. Post, Rare earth metal disilicides. Journalof disilicides of heavy rare earth metals. Journal of theRefractory Carbides, Rare Earth Silicides, Metal Nitrides,

  17. Uranium Mill Tailings Remedial Action Project (UMTRAP), Slick Rock, Colorado, Revision 1, Volume 3. Calculations, Final design for construction

    SciTech Connect (OSTI)

    NONE

    1995-09-01T23:59:59.000Z

    Volume three contains calculations for: site hydrology--rainfall intensity, duration, and frequency relations; site hydrology-- probable maximum precipitation; erosion protection--rock quality evaluation; erosion protection--embankment top and side slope; erosion protection--embankment toe apron; erosion protection-- gradations and layer thicknesses; Union Carbide site--temporary drainage ditch design; Union Carbide site--retention basin sediment volume; Union Carbide site--retention basin sizing; Burro Canyon site temporary drainage--temporary drainage facilities; and Union Carbide site temporary drainage--water balance.

  18. Next Generation Power Electronics National Manufacturing Innovation...

    Broader source: Energy.gov (indexed) [DOE]

    Corporation (TX) - Transphorm, Inc. (CA) - United Si Carbide, Inc. (NJ) - Vacon Plc. (NC) Universities and Labs: - North Carolina State University (Lead) - Arizona State...

  19. TEMPERATURE-PROGRAMMED DESORPTION AND REACTION OF CO AND H2 ON ALUMINA-SUPPORTED RUTHENIUM CATALYST

    E-Print Network [OSTI]

    Low, Gordon Gongngai

    2011-01-01T23:59:59.000Z

    and R. Anderson, "The Fischer-Tropsch Related Synthesis",carbide theory of Fischer and Tropsch postulated that thereactions are still (Fischer-Tropsch synthesis) from CO and

  20. PRELIMINARY SURVEY OF WESTINGHOUSE ELECTRIC CORPORATION EAST...

    Office of Legacy Management (LM)

    OAK RIDGE NATIONAL LABORATORY operated by UNION CARBIDE CORPORATION for the DEPARTMENT OF ENERGY as part of the Formerly Utilized Sites-- Remedial Action Program WESTINGHOUSE...

  1. Bi-directional dc-dc Converter

    Broader source: Energy.gov (indexed) [DOE]

    Purpose of Work for FY08 1. Vehicle modeling, simulation, and operation voltages optimization. 2. DC-DC Power converter and control modeling. 3. Silicon Carbide device...

  2. BrickandMortar SelfAssembly Approach to Graphitic Mesoporous...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    percolation. 11 Carbon materials that are used for applications such as supercapacitor electrodes include activated carbon, carbide derived carbon, templated carbon, ...

  3. ct200914j 1..6

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CDC materials to enhance the SSA of electrodes as well as the capacitance of supercapacitor, by selective etching of metal carbides in a chlorine-containing environment....

  4. Energy Dissipation and Defect Generation for Nanocrystalline...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Defect Generation for Nanocrystalline Silicon Carbide. Abstract: Large-scale molecular dynamics simulations have been employed to study defect generation and primary damage...

  5. Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant

    DOE Patents [OSTI]

    LaCamera, Alfred F. (Trafford, PA)

    2002-11-05T23:59:59.000Z

    A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000.degree. C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.

  6. Thermodynamic study of the MWG system/components and measurement of the oxygen partial pressure in the heat source capsule

    SciTech Connect (OSTI)

    David, D.J.

    1980-06-23T23:59:59.000Z

    A thermodynamic study of the Milliwatt Generator heat source capsule was performed to determine the effects of the oxide fuel on container materials at elevated temperatures in order to evaluate the factors affecting embrittlement of T-111 alloy. The study indicates that relatively slow oxidation of the T-111 of the capsule occurs during pretreatment. Yttrium added to the /sup 238/PuO/sub 2/ fuel charge is functioning in its designed role as an oxygen getter and is stabilizing at an O/Pu ratio of 1.75. The free energy of formation of hafnium oxide has been measured and found to be -70632 cal/mole; this suggests that the ability of hafnium to strongly function as an oxygen getter may be largely determined by the kinetics, and the free energy may play a lesser role.

  7. High quality transparent conducting oxide thin films

    DOE Patents [OSTI]

    Gessert, Timothy A. (Conifer, CO); Duenow, Joel N. (Golden, CO); Barnes, Teresa (Evergreen, CO); Coutts, Timothy J. (Golden, CO)

    2012-08-28T23:59:59.000Z

    A transparent conducting oxide (TCO) film comprising: a TCO layer, and dopants selected from the elements consisting of Vanadium, Molybdenum, Tantalum, Niobium, Antimony, Titanium, Zirconium, and Hafnium, wherein the elements are n-type dopants; and wherein the transparent conducting oxide is characterized by an improved electron mobility of about 42 cm.sup.2/V-sec while simultaneously maintaining a high carrier density of .about.4.4e.times.10.sup.20 cm.sup.-3.

  8. Dispersion engineered high-Q silicon Nitride Ring-Resonators via Atomic Layer Deposition

    E-Print Network [OSTI]

    Riemensberger, Johann; Herr, Tobias; Brasch, Victor; Holzwarth, Ronald; Kippenberg, Tobias J

    2012-01-01T23:59:59.000Z

    We demonstrate dispersion engineering of integrated silicon nitride based ring resonators through conformal coating with hafnium dioxide deposited on top of the structures via atomic layer deposition (ALD). Both, magnitude and bandwidth of anomalous dispersion can be significantly increased. All results are confirmed by high resolution frequency-comb-assisted-diode-laser spectroscopy and are in very good agreement with the simulated modification of the mode spectrum.

  9. Amorphous metal alloy and composite

    DOE Patents [OSTI]

    Wang, Rong (Richland, WA); Merz, Martin D. (Richland, WA)

    1985-01-01T23:59:59.000Z

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  10. Method of drill bit manufacture and product

    SciTech Connect (OSTI)

    Miller, R.R.; Ault, J.E.; Barber, R.B. Jr.; Hampel, D.A.

    1984-06-12T23:59:59.000Z

    A method is claimed for making a drill bit and product resulting therefrom in which carbide elements are coated with carbide and nitride materials such as those of titanium as by chemical vapor deposition after which the elements are cast in molten steel.

  11. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOE Patents [OSTI]

    Corman, Gregory Scot (Ballston Lake, NY); Luthra, Krishan Lal (Schenectady, NY)

    1999-01-01T23:59:59.000Z

    A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  12. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOE Patents [OSTI]

    Corman, Gregory Scot (Ballston Lake, NY); Luthra, Krishan Lal (Schenectady, NY)

    2002-01-01T23:59:59.000Z

    A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  13. DEVELOPMENT AND ON-LINE TESTS OF DIFFERENT TARGET-ION SOURCE UNITS FOR PRODUCTION OF NUCLIDES FAR FROM STABILITY

    E-Print Network [OSTI]

    Titov, Anatoly

    as a general goal the development of a massive (up to 1 kg) uranium carbide target prototype for the third beams. For more than thirty years UCx targets have been explored for the production of a large set of neutron-rich and neutron-deficient heavy nuclei. The main line of uranium carbide target development

  14. Ceramic-bonded abrasive grinding tools

    DOE Patents [OSTI]

    Holcombe, Jr., Cressie E. (Farragut, TN); Gorin, Andrew H. (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN)

    1994-01-01T23:59:59.000Z

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  15. Ceramic-bonded abrasive grinding tools

    DOE Patents [OSTI]

    Holcombe, C.E. Jr.; Gorin, A.H.; Seals, R.D.

    1994-11-22T23:59:59.000Z

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  16. JOURNAL DE PHYSIQUE IV C2-633 Colloque C2, suppl. au Journal de Physique 11, Vol. 1, septembre 1991

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    temperature of about 850°C, respectively from butane and nitrogen and a mixture of titanium chloridesBans cedex 2, France Abstract : Titanium carbide and nitride coatings can be deposited at a moderate, by Ti metal. Under optimized deposition conditions, a very hard titanium carbide with a polynucleated

  17. Dispersion toughened silicon carbon ceramics

    DOE Patents [OSTI]

    Wei, G.C.

    1984-01-01T23:59:59.000Z

    Fracture resistant silicon carbide ceramics are provided by incorporating therein a particulate dispersoid selected from the group consisting of (a) a mixture of boron, carbon and tungsten, (b) a mixture of boron, carbon and molybdenum, (c) a mixture of boron, carbon and titanium carbide, (d) a mixture of aluminum oxide and zirconium oxide, and (e) boron nitride. 4 figures.

  18. Novel hard compositions and methods of preparation

    DOE Patents [OSTI]

    Sheinberg, Haskell (Los Alamos, NM)

    1983-08-23T23:59:59.000Z

    Novel very hard compositions of matter are prepared by using in all embodiments only a minor amount of a particular carbide (or materials which can form the carbide in situ when subjected to heat and pressure); and no strategic cobalt is needed. Under a particular range of conditions, densified compositions of matter of the invention are prepared having hardnesses on the Rockwell A test substantially equal to the hardness of pure tungsten carbide and to two of the hardest commercial cobalt-bonded tungsten carbides. Alternately, other compositions of the invention which have slightly lower hardnesses than those described above in one embodiment also possess the advantage of requiring no tungsten and in another embodiment possess the advantage of having a good fracture toughness value. Photomicrographs show that the shapes of the grains of the alloy mixture with which the minor amount of carbide (or carbide-formers) is mixed are radically altered from large, rounded to small, very angular by the addition of the carbide. Superiority of one of these hard compositions of matter over cobalt-bonded tungsten carbide for ultra-high pressure anvil applications was demonstrated.

  19. UPDATE ON SIC-BASED INVERTER TECHNOLOGY Abstract This paper presents a study of Silicon

    E-Print Network [OSTI]

    Tolbert, Leon M.

    UPDATE ON SIC-BASED INVERTER TECHNOLOGY Abstract ­ This paper presents a study of Silicon Carbide, Silicon carbide (SiC) I. INTRODUCTION The role of power electronics in the electrical energy conversion sector is increasing by the decade [1]. Also, with the growth of power electronics as the interface

  20. Ab initio Molecular Dynamics and Elastic Properties of TiC and TiN Nanoparticles A. V. Postnikov and P. Entel

    E-Print Network [OSTI]

    Entel, P.

    and vibrational modes are presented for titanium carbide and titanium nitride clusters of nearly stoichiometric of acoustic modes. INTRODUCTION Titanium carbide and nitride prepared as nanoparticles find many applications-principle calculations of vibration frequencies and patterns is a reliable and precision method to extract total energy