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Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
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1

Synthesis and Characterization of Single Crystalline Hafnium Carbide Nanowires  

E-Print Network (OSTI)

transition metal carbide (TMC) nanowires has been reported, no HfC nanowires have been successfully syntheSynthesis and Characterization of Single Crystalline Hafnium Carbide Nanowires Jinshi Yuan,,§ Han carbide (HfC) is the most refractory compound known to mankind. A catalyst-assisted chemical vapor deposi

Qin, Lu-Chang

2

SIGNATURES OF THE s-PROCESS IN PRESOLAR SILICON CARBIDE GRAINS: BARIUM THROUGH HAFNIUM  

E-Print Network (OSTI)

SIGNATURES OF THE s-PROCESS IN PRESOLAR SILICON CARBIDE GRAINS: BARIUM THROUGH HAFNIUM Qing-Zhu Yin have been determined in a silicon carbide­rich sample of the Murchison carbonaceous chondrite, using carbide, silicon nitride, and various refractory oxides (e.g., Zinner 1998). Grains of silicon carbide (Si

Lee, Cin-Ty Aeolus

3

Development of single crystal filaments. Final report  

SciTech Connect

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.

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

1995-04-01T23:59:59.000Z

4

It's Elemental - The Element Hafnium  

NLE Websites -- All DOE Office Websites (Extended Search)

Lutetium Lutetium Previous Element (Lutetium) The Periodic Table of Elements Next Element (Tantalum) Tantalum The Element Hafnium [Click for Isotope Data] 72 Hf Hafnium 178.49 Atomic Number: 72 Atomic Weight: 178.49 Melting Point: 2506 K (2233°C or 4051°F) Boiling Point: 4876 K (4603°C or 8317°F) Density: 13.3 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 6 Group Number: 4 Group Name: none What's in a name? From the Latin word for the city of Copenhagen, Hafnia. Say what? Hafnium is pronounced as HAF-neeem. History and Uses: Hafnium was discovered by Dirk Coster, a Danish chemist, and Charles de Hevesy, a Hungarian chemist, in 1923. They used a method known as X-ray spectroscopy to study the arrangement of the outer electrons of atoms in

5

Formulation and method for preparing gels comprising hydrous hafnium oxide  

DOE Patents (OSTI)

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.

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

2013-08-06T23:59:59.000Z

6

E-Print Network 3.0 - alpha -particle-irradiated hafnium Sample...  

NLE Websites -- All DOE Office Websites (Extended Search)

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

7

Carbide and carbonitride surface treatment method for refractory metals  

DOE Patents (OSTI)

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.

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

1996-12-03T23:59:59.000Z

8

Hafnium nitride for hot carrier solar cells  

Science Journals Connector (OSTI)

Abstract Hot carrier solar cells is an attractive technology with the potential of reaching high energy conversion efficiencies approaching the thermodynamic limit of infinitely stacked multi-junction solar cells: 65% under one sun and 86% under maximally concentrated. The hot carrier solar cell is conceptually simple consisting of two key components: absorber and energy selective contacts. High efficiencies are achieved by minimising the energy lost to thermalisaton of hot photo-generated carriers while absorbing majority of the solar spectrum. For this to be achieved, energy selective contacts are required to allow the extraction of carriers fast enough at an energy level above the electronic band edge. It is critical for the absorber to be able to maintain a hot carrier population for a sufficiently long time period for the extraction of carriers while they are hot. Bulk materials with a large gap between acoustic and optical branches in the phonon dispersion are predicted to exhibit slow hot carrier thermalisation rates. Hafnium nitride is such a material with a large gap in its phonon dispersion and is identified as a potential material to be used as a hot carrier absorber. Hafnium nitride has been deposited using reactive sputtering and characterised to investigate material properties and carrier cooling rates.

Simon Chung; Santosh Shrestha; Xiaoming Wen; Yu Feng; Neeti Gupta; Hongze Xia; Pyng Yu; Jau Tang; Gavin Conibeer

2014-01-01T23:59:59.000Z

9

Microwave sintering of boron carbide  

DOE Patents (OSTI)

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.

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

1988-06-10T23:59:59.000Z

10

As-Received, Ozone Cleaned and Ar+ Sputtered Surfaces of Hafnium Oxide Grown by Atomic Layer Deposition and Studied by XPS  

SciTech Connect

In this study, X-ray photoelectron spectroscopy (XPS) characterization was performed on 47 nm thick hafnium oxide (HfO{sub 2}) films grown by atomic layer deposition using TEMA-Hf/H{sub 2}O at 250 C substrate temperature. HfO{sub 2} is currently being studied as a possible replacement for Silicon Oxide (SiO{sub 2}) as a gate dielectric in electronics transistors. XPS spectra were collected on a Physical Electronics Quantum 2000 Scanning ESCA Microprobe using a monochromatic Al K{sub a} X-ray (1486.7 eV) excitation source. The sample was analyzed under the following conditions: as received, after UV irradiation for five minutes, and after sputter cleaning with 2 kV Ar{sup +} ions for 180 seconds. Survey scans showed carbon, oxygen, and hafnium as the major species in the film, while the only minor species of argon and carbide was detected after sputtering. Adventitious carbon initially composed approximately 18.6 AT% of the surface, but after UV cleaning it was reduced to 2.4 AT%. This demonstrated that that the majority of carbon was due to adventitious carbon. However, after 2 kV Ar{sup +} sputtering there was still only trace amounts of carbon at {approx}1 AT%, Some of this trace carbon is now in the form of a carbide due to the interaction with Ar{sup +} used for sputter cleaning. Furthermore, the stoiciometric ratio of oxygen and hafnium is consistent with a high quality HfO{sub 2} film.

Engelhard, Mark H.; Herman, Jacob A.; Wallace, Robert; Baer, Donald R.

2012-06-27T23:59:59.000Z

11

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

E-Print Network (OSTI)

%; South Africa, 37%; China, 3%; Canada, 1%; and other, 2%. Zirconium, unwrought, including powder: France coatings, and sandblasting. The leading consumers of zirconium and hafnium metal are the nuclear energy Kingdom, 5%; and other, 9%. Tariff: Item Number Normal Trade Relations 12-31-08 Zirconium ores

12

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

E-Print Network (OSTI)

of hafnium metal was insignificant. Import Sources (1997-2000): Zirconium ores and concentrates: South Africa%; Germany, 7%; United Kingdom, 2%; and other, 9%. Tariff: Item Number Normal Trade Relations 12 Stockpile, the U.S. Department of Energy (DOE) held over 500 tons of zirconium in various forms. DOE also

13

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

E-Print Network (OSTI)

Sources (2002-05): Zirconium ores and concentrates: Australia, 57%; South Africa, 35%; China, 4%; Canada consumers of zirconium and hafnium metal are the nuclear energy and chemical process industries. Salient%; Japan, 4%; and other, 2%. Tariff: Item Number Normal Trade Relations 12-31-06 Zirconium ores

14

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

E-Print Network (OSTI)

of hafnium metal was insignificant. Import Sources (1998-2001): Zirconium ores and concentrates: South Africa%; Germany, 8%; United Kingdom, 3%; and other, 9%. Tariff: Item Number Normal Trade Relations 12,838 short tons) of zirconium ore (baddeleyite) during fiscal year 2002. The U.S. Department of Energy (DOE

15

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

E-Print Network (OSTI)

concentrates: South Africa, 52%; Australia, 43%; and other, 5%. Zirconium, unwrought, including powder: Japan. The leading consumers of zirconium metal and hafnium metal are the nuclear energy and chemical process, 58%; Australia, 24%; Germany, 11%; other, 7%. Tariff: Item Number Normal Trade Relations 12

16

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

E-Print Network (OSTI)

%; South Africa, 46%; China, 3%; Russia, 1%; and other, 1%. Zirconium, unwrought, including powder: France coatings, and sandblasting. The leading consumers of zirconium and hafnium metal are the nuclear energy, 21%; Canada, 8%; United Kingdom, 6%; and other, 5%. Tariff: Item Number Normal Trade Relations 12

17

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

E-Print Network (OSTI)

was insignificant. Import Sources (2008­11): Zirconium mineral concentrates: Australia, 52%; South Africa, 42. The leading consumers of zirconium metal and hafnium metal are the nuclear energy and chemical process: Item Number Normal Trade Relations 12­31­12 Zirconium ores and concentrates 2615.10.0000 Free

18

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

E-Print Network (OSTI)

concentrates: Australia, 49%; South Africa, 44%; and other, 7%. Zirconium, unwrought, including powder: Germany. The leading consumers of zirconium metal and hafnium metal are the nuclear energy and chemical process, 17%; United Kingdom, 5%; and other, 9%. Tariff: Item Number Normal Trade Relations 12-31-11 Zirconium

19

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

E-Print Network (OSTI)

%; South Africa, 32%; China, 4%; Canada, 2%; and other, 1%. Zirconium, unwrought, including powder: France coatings, and sandblasting. The leading consumers of zirconium and hafnium metal are the nuclear energy, 2%; Austria, 1%; and other, 1%. Tariff: Item Number Normal Trade Relations 12-31-07 Zirconium ores

20

Amorphous hafnium-indium-zinc oxide semiconductor thin film transistors  

Science Journals Connector (OSTI)

We reported on the performance and electrical properties of co-sputtering-processed amorphous hafnium-indium-zinc oxide (?-HfIZO) thin film transistors (TFTs). Co-sputtering-processed ?-HfIZO thin films have shown an amorphous phase in nature. ...

Sheng-Po Chang; San-Syong Shih

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Carbide and carbonitride surface treatment method for refractory metals  

DOE Patents (OSTI)

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.

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

1996-01-01T23:59:59.000Z

22

A look back at Union Carbides FIRST 20 Years in Nuclear Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

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 Company, operated...

23

A look back at Union Carbides FIRST 20 Years in Nuclear Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

Union Carbide in Nuclear Energy Note: Union Carbide Nuclear Division, which started out as Carbide and Carbon Chemicals Company, operated the Atomic Energy CommissionEnergy...

24

Aerogel-supported filament  

DOE Patents (OSTI)

The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces. 6 Figs.

Wuest, C.R.; Tillotson, T.M.; Johnson, C.V. III

1995-05-16T23:59:59.000Z

25

Oxygen and nitrogen diffusion in ?-hafnium from first principles  

SciTech Connect

We use a combination of density functional theory and multistate diffusion formalism to analyze the diffusion of oxygen and nitrogen in technologically important hafnium metal. Comparing the local density approximation and the Perdew-Burke-Ernzerhof version of the generalized gradient approximation, we find that a better description of the hafnium lattice in the latter results in the correct sequence of stable and transition states for oxygen interstitials leading to essentially quantitative agreement with experiment. For oxygen diffusion, we find an isotropic temperature-dependent diffusion coefficient of D=0.082e{sup ?2.04/k{sub B}T}cm{sup 2}s{sup ?1} utilizing interstitial sites with hexahedral and octahedral coordination. For the diffusivity of nitrogen, we find that an additional stable interstitial site, the crowdion site, exists and that the diffusion coefficient is D=0.15e{sup ?2.68/k{sub B}T}cm{sup 2}s{sup ?1}. Our results also reproduce the experimental observation that nitrogen diffusivity is lower than that of oxygen in hafnium.

O'Hara, Andrew; Demkov, Alexander A., E-mail: demkov@physics.utexas.edu [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

2014-05-26T23:59:59.000Z

26

Modified silicon carbide whiskers  

DOE Patents (OSTI)

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.

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

1991-05-21T23:59:59.000Z

27

Modified silicon carbide whiskers  

DOE Patents (OSTI)

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.

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

1991-01-01T23:59:59.000Z

28

Process for microwave sintering boron carbide  

DOE Patents (OSTI)

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.

Holcombe, C.E.; Morrow, M.S.

1993-10-12T23:59:59.000Z

29

Nanoscale Engineering Of Radiation Tolerant Silicon Carbide....  

NLE Websites -- All DOE Office Websites (Extended Search)

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

30

Process for microwave sintering boron carbide  

DOE Patents (OSTI)

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.

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

31

Chaperonin filaments: The archael cytoskeleton  

SciTech Connect

Chaperonins are multi-subunit double-ring complexed composed of 60-kDa proteins that are believed to mediate protein folding in vivo. The chaperonins in the hyperthermophilic archaeon Sulfolobus shibatae are composed of the organism`s two most abundant proteins, which represent 4% of its total protein and have an intracellular concentration of {ge} 3.0 mg/ml. At concentrations of 1.0 mg/ml, purified chaperonin proteins aggregate to form ordered filaments. Filament formation, which requires Mg{sup ++} and nucleotide binding (not hydrolysis), occurs at physiological temperatures under conditions suggesting filaments may exist in vivo. If the estimated 4,600 chaperonins per cell, formed filaments in vivo, they could create a matrix of filaments that would span the diameter of an average S. shibatae cell 100 times. Direct observations of unfixed, minimally treated cells by intermediate voltage electron microscopy (300 kV) revealed an intracellular network of filaments that resembles chaperonin filaments produced in vitro. The hypothesis that the intracellular network contains chaperonins is supported by immunogold analyses. The authors propose that chaperonin activity may be regulated in vivo by filament formation and that chaperonin filaments may serve a cytoskeleton-like function in archaea and perhaps in other prokaryotes.

Trent, J.D.; Kagawa, H.K.; Yaoi, Takuro; Olle, E.; Zaluzec, N.J.

1997-08-01T23:59:59.000Z

32

Carbide Precipitation in Steel Weld Metals  

E-Print Network (OSTI)

Carbide Precipitation in Steel Weld Metals www.msm.cam.ac.uk/phase-trans #12 diffusion into austenite Carbon diffusion into austenite and carbide precipitation in ferrite Carbide precipitation from austenite CASE 2: elimination of carbides #12;#12;#12;0.110.090.070.050.03 0.2 0.4 0.6 0.8 1

Cambridge, University of

33

Microwave processing for carbide ceramics  

SciTech Connect

The US Bureau of Mines (USBM) has developed a process for synthesizing carbide ceramics in a microwave-induced plasma (MIP). For example, the process forms tungsten carbide with only 0.04% free carbon impurity at an average particle size of 0.05 {mu}m. Starting materials are tungsten oxide, carbon, and carbon monoxide. Commercial methods to produce tungsten carbide require heating to 1,500 C for up to 7 hours. Using the USBM method, tungsten carbide can be produced in approximately 10 minutes using a 30 kW, 915 mHz microwave unit. The reaction is carried out in a short-circuited waveguide to create a standing wave. Reactants rest on a carbon pedestal inside a closed zirconia crucible filled with carbon monoxide. The crucible is place at a field maximum within the waveguide. The waveguide was filled with helium to protect the waveguide. A procedure for producing carbide on a larger scale is described. Other ceramic compounds have been produced using this method, including silicon carbide and titanium carbide.

Tolley, W.K.; Church, R.H. [Bureau of Mines, Salt Lake City, UT (United States). Salt Lake City Research Center

1995-08-01T23:59:59.000Z

34

Rheology of silicon carbide/vinyl ester nanocomposites  

E-Print Network (OSTI)

New York, 1999. SILICON CARBIDE/VINYL ESTER NANOCOMPOSITESRheology of Silicon Carbide/Vinyl Ester NanocompositesABSTRACT: Silicon carbide (SiC) nanoparticles with no

Yong, Virginia; Hahn, H. Thomas

2006-01-01T23:59:59.000Z

35

Silicon Carbide, SiC  

Science Journals Connector (OSTI)

Silicon carbide occurring naturally as hexagonal crystals and associated with diamond, graphite, and amorphous carbon was first reported in 1904/05 by Moissan as a component of the hydrochloric acid insoluble ...

Vera Haase; Gerhard Kirschstein; Hildegard List; Sigrid Ruprecht

1985-01-01T23:59:59.000Z

36

Hafnium metallocene compounds used as cathode interfacial layers for enhanced electron transfer in organic solar cells  

Science Journals Connector (OSTI)

We have used hafnium metallocene compounds as cathode interfacial layers for organic solar cells [OSCs]. A metallocene compound consists of...6, 6]-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl...

Keunhee Park; Seungsik Oh; Donggeun Jung; Heeyeop Chae

2012-01-01T23:59:59.000Z

37

Electron emitting filaments for electron discharge devices  

DOE Patents (OSTI)

Electrons are copiously emitted by a device comprising a loop-shaped filament made of lanthanum hexaboride. The filament is directly heated by an electrical current produced along the filament by a power supply connected to the terminal legs of the filament. To produce a filament, a diamond saw or the like is used to cut a slice from a bar made of lanthanum hexaboride. The diamond saw is then used to cut the slice into the shape of a loop which may be generally rectangular, U-shaped, hairpin-shaped, zigzag-shaped, or generally circular. The filaments provide high electron emission at a relatively low operating temperature, such as 1600/sup 0/C. To achieve uniform heating, the filament is formed with a cross section which is tapered between the opposite ends of the filament to compensate for nonuniform current distribution along the filament due to the emission of electrons from the filament.

Leung, K.N.; Pincosy, P.A.; Ehlers, K.W.

1983-06-10T23:59:59.000Z

38

Growth mode evolution of hafnium oxide by atomic layer deposition  

SciTech Connect

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 heightheight 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.

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

39

Atomic Layer Deposition of Insulating Hafnium and Zirconium Nitrides  

E-Print Network (OSTI)

author. E-mail: gordon@chemistry.harvard.edu. (1) Toth, L. E. Transition Metal Carbides and Nitrides homoleptic tetrakis(dialkylamido)- metal(IV) complexes and ammonia at low substrate temperatures (150-250 °C). The precursor vapors were alternately pulsed into a heated reactor, yielding 1.15-1.20 ? of metal nitride film

40

Combustion Synthesis of Silicon Carbide 389 Combustion Synthesis of Silicon Carbide  

E-Print Network (OSTI)

Combustion Synthesis of Silicon Carbide 389 X Combustion Synthesis of Silicon Carbide Alexander S velocity and 17 #12;Properties and Applications of Silicon Carbide390 reaction rate throughout the mixture by graphite during SHS of carbides. Local reaction initiation is typically accomplished by hot tungsten wire

Mukasyan, Alexander

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Classification of Carbide Distributions using ScaleSpace Methods Classification of Carbide Distributions using Scale  

E-Print Network (OSTI)

Classification of Carbide Distributions using Scale­Space Methods #12; Classification of Carbide­structure of the steel, which in turn influences the mechanical properties. Specifi­ cally, the distribution of carbide is essential, since cracks propagate within the carbide agglomerations. In current quality control

Lindeberg, Tony

42

3 Carbide Precipitation Carbides are largely responsible for the commercial failure of many of the early  

E-Print Network (OSTI)

.1. Transition carbides, such as and the various orthorhombic forms listed in Table 3.1, only form because Precipitation 64 Table 3.1 Carbides in bainite or in tempered bainite. Fe, M/C is the ratio of metal to car- bon3 Carbide Precipitation Carbides are largely responsible for the commercial failure of many

Cambridge, University of

43

Studies on the dynamics of limited filaments  

E-Print Network (OSTI)

A study on the dynamics of filaments in the presence of a diagnostic, conductive limiter is presented. Plasma filaments are coherent structures present in many fusion devices and transport a significant amount of particles ...

Bonde, Jeffrey David

2010-01-01T23:59:59.000Z

44

Composition and microstructure of zirconium and hafnium germanates obtained by different chemical routes  

SciTech Connect

The phase composition and morphology of zirconium and hafnium germanates synthesized by ceramic and co-precipitation routes were studied. The products were characterized using high-temperature X-ray diffraction analysis (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and thermal (TG/DTA) analysis. To investigate the phase composition and stoichiometry of compounds the unit cell parameters were refined by full-profile Rietveld XRD analysis. The morphology of products and its evolution during high-temperature treatment was examined by SEM analysis. It was stated that there is the strong dependence of the phase composition and morphology of products on the preparation route. The ceramic route requires a multi-stage high-temperature treatment to obtain zirconium and hafnium germanates of 95% purity or more. Also, there are strong diffusion limitations to obtain hafnium germanate Hf{sub 3}GeO{sub 8} by ceramic route. On the contrary, the co-precipitation route leads to the formation of nanocrystalline single phase germanates of stoichiometric composition at a relatively low temperatures (less than 1000 C). The results of quantitative XRD analysis showed the hafnium germanates are stoichiometric compounds in contrast to zirconium germanates that form a set of solid solutions. This distinction may be related to the difference in the ion radii of Zr and Hf. - Graphical abstract: The phase composition and morphology of zirconium and hafnium germanates synthesized by ceramic and co-precipitation routes were studied. It was stated that there is the strong dependence of the phase composition and morphology of products on the preparation route. Display Omitted - Highlights: Zr and Hf germanates were synthesized by ceramic and co-precipitation routes. The morphology of products depends on the synthesis parameters. Zirconium germanates forms a set of solid solutions. Hafnium germanates are stoichiometric compounds.

Utkin, A.V., E-mail: utkinalex@hotmail.com; Prokip, V.E.; Baklanova, N.I.

2014-01-15T23:59:59.000Z

45

Abrasive slurry composition for machining boron carbide  

DOE Patents (OSTI)

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.

Duran, Edward L. (Santa Fe, NM)

1985-01-01T23:59:59.000Z

46

Microstructure and properties of IN SITU toughened silicon carbide  

E-Print Network (OSTI)

IN SITU TOUGHENED SILICON CARBIDE LUTGARD C. DE JONGHE 1,2 ,In Situ Toughened Silicon Carbide Lutgard C. De Jonghe 1,2 ,USA ABSTRACT A silicon carbide with a fracture toughness as

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

2003-01-01T23:59:59.000Z

47

Detecting filaments at z=3  

E-Print Network (OSTI)

We present the detection of a filament of Ly-alpha emitting galaxies in front of the quasar Q1205-30 at z=3.04 based on deep narrow band imaging and follow-up spectroscopy obtained at the ESO NTT and VLT. We argue that Ly-alpha selection of high redshift galaxies with relatively modest amounts of observing time allows the detection and redshift measurement of galaxies with sufficiently high space densities that we can start to map out the large scale structure at z=2-3 directly. Even more interesting is it that a 3D map of the filaments will provide a new cosmological test for the value of the cosmological constant, Omega_Lambda.

J. P. U. Fynbo; P. Moller; B. Thomsen

2001-10-29T23:59:59.000Z

48

Method for making boron carbide cermets  

DOE Patents (OSTI)

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.

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

1987-11-03T23:59:59.000Z

49

Method for making boron carbide cermets  

DOE Patents (OSTI)

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.

Cline, Carl F. (Danville, CA); Fulton, Fred J. (Livermore, CA)

1987-01-01T23:59:59.000Z

50

Crystal Structure and Formation Energy of -carbide Using First  

E-Print Network (OSTI)

Crystal Structure and Formation Energy of -carbide Using First Principles CalculationsIntroduction · Martensite (') -carbide -carbide -carbide Cementite () · Silicon promotes the formation of -carbide below-456(2008) 900, 100s 200, 20s 250, 30 s Ms = 302(1.0 wt%Si), 293 (1.7 wt%Si) 1.0wt% Si : No -carbide 1.7wt% Si

Cambridge, University of

51

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

E-Print Network (OSTI)

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), ...

Gabert, Andrea Jennifer

2007-01-01T23:59:59.000Z

52

Mechanisms of tungsten carbide-cobalt nanoparticle-induced angiogenesis.  

E-Print Network (OSTI)

??Hard metal or cemented carbide consists of a powder mixture of 80 to 90% oftungsten carbide (WC) and 5 to 10% of metallic cobalt (Co). (more)

Zhu, Yingxue.

2010-01-01T23:59:59.000Z

53

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

NLE Websites -- All DOE Office Websites (Extended Search)

modeling of amorphous silicon carbide using a bond-order potential. Atomistic modeling of amorphous silicon carbide using a bond-order potential. Abstract: Molecular dynamics...

54

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Award-Winning Silicon Carbide Power Electronics (October 2012) Fact Sheet: Award-Winning Silicon Carbide Power Electronics (October 2012) Operating at high temperatures and with...

55

Amorphization of Silicon Carbide by Carbon Displacement. | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

of Silicon Carbide by Carbon Displacement. Amorphization of Silicon Carbide by Carbon Displacement. Abstract: We have used molecular dynamics simulations to examine the possibility...

56

Titanium Carbide Bipolar Plate for Electrochemical Devices  

SciTech Connect

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

LaConti, Anthony B.; Griffith, Arthur E.; Cropley, Cecelia C.; Kosek, John A.

1998-05-08T23:59:59.000Z

57

Measurement of birefringence inside a filament  

SciTech Connect

We quantified the ultrafast birefringence induced in the filament in an atomic gas by measuring the filament-induced polarization rotation of a probe pulse. Based on the dephasing of the probe's orthogonal polarization components in argon, the experiment was done at 1 atm by copropagating a linearly polarized 400-nm probe pulse with an 800-nm pump pulse which generated the filament. The probe's elliptical polarization states were shown under various initial pump-probe polarization schemes. These states were verified by comparing the filament-induced probe polarization rotation angle and the ellipticity of the probe polarization.

Yuan Shuai [Centre d'Optique, Photonique et Laser (COPL) et Departement de physique, de genie physique et d'optique, Universite Laval, Quebec, Quebec G1V 0A6 (Canada); State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Wang, Tie-Jun; Chin, See Leang [Centre d'Optique, Photonique et Laser (COPL) et Departement de physique, de genie physique et d'optique, Universite Laval, Quebec, Quebec G1V 0A6 (Canada); Kosareva, Olga; Panov, Nikolay; Makarov, Vladimir [International Laser Center and Faculty of Physics, Lomonosov Moscow State University, Moscow (Russian Federation); Zeng Heping [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

2011-07-15T23:59:59.000Z

58

Inter-filament Attractions Narrow the Length Distribution of Actin Filaments  

E-Print Network (OSTI)

We show that the exponential length distribution that is typical of actin filaments under physiological conditions dramatically narrows in the presence of (i) crosslinker proteins (ii) polyvalent counterions or (iii) depletion mediated attractions. A simple theoretical model shows that in equilibrium, short-range attractions enhance the tendency of filaments to align parallel to each other, eventually leading to an increase in the average filament length and a decrease in the relative width of the distribution of filament lengths.

David Biron; Elisha Moses; Itamar Borukhov; S. A. Safran

2004-06-13T23:59:59.000Z

59

The WSRT virgo filament survey  

E-Print Network (OSTI)

In the last few years the realization has emerged that the universal baryons are almost equally distributed by mass in three components: (1) galactic concentrations, (2) a warm-hot intergalactic medium (WHIM) and (3) a diffuse intergalactic medium. These three components are predicted by hydrodynamical simulations and are probed by QSO absorption lines. To observe the WHIM in neutral hydrogen, observations are needed which are deeper than log(N$_{HI}$)=18. The WHIM should appear as a Cosmic Web, underlying the galaxies with higher column densities. We have used the WSRT, to simulate a filled aperture by observing at very high hour angles, to reach very high column density sensitivity. To achieve even higher image fidelity, an accurate model of the WSRT primary beam was developed. This will be used in the joint deconvolution of the observations. To get a good overview of the distribution and kinematics of the Cosmic Web, a deep survey of 1500 square degrees of sky was undertaken, containing the galaxy filament extending between the Local Group and the Virgo Cluster. The auto-correlation data has been reduced and has an RMS of $\\Delta N_{HI} = 4.2\\times10^{16}$ cm$^{-2}$ over 20 kms$^{-1}$. Several sources have been tentatively detected, which were previously unknown, as well as an indication for diffuse intergalactic filaments.

Attila Popping; Robert Braun

2007-03-27T23:59:59.000Z

60

Classi cation of Carbide Distributions using Scale-Space Methods Classi cation of Carbide Distributions using Scale  

E-Print Network (OSTI)

Classi cation of Carbide Distributions using Scale-Space Methods #12;Classi cation of Carbide-structure of the steel, which in turn in uences the mechanical properties. Speci - cally, the distribution of carbide is essential, since cracks propagate within the carbide agglomerations. In current quality control

Lindeberg, Tony

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Manufacture of silicon carbide using solar energy  

DOE Patents (OSTI)

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.

Glatzmaier, Gregory C. (Boulder, CO)

1992-01-01T23:59:59.000Z

62

Radiation characteristics and optical properties of filamentous cyanobacterium Anabaena cylindrica  

Science Journals Connector (OSTI)

This study presents experimental measurements of the absorption and scattering cross sections and the spectral complex index of refraction of filamentous cyanobacteria. Filamentous...

Heng, Ri-Liang; Lee, Euntaek; Pilon, Laurent

2014-01-01T23:59:59.000Z

63

Chemical solution deposition of ferroelectric yttrium-doped hafnium oxide films on platinum electrodes  

SciTech Connect

Ferroelectric hafnium oxide films were fabricated by chemical solution deposition with a remnant polarization of >13 ?C/cm{sup 2}. The samples were prepared with 5.2?mol.?% yttrium-doping and the thickness varied from 18?nm to 70?nm. The hafnium oxide layer was integrated into a metal-insulator-metal capacitor using platinum electrodes. Due to the processing procedure, no thickness dependence of the ferroelectric properties was observed. To confirm the ferroelectric nature of the deposited samples, polarization, capacitance, and piezoelectric displacement measurements were performed. However, no evidence of the orthorhombic phase was found which has been proposed to be the non-centrosymmetric, ferroelectric phase in HfO{sub 2}.

Starschich, S.; Griesche, D.; Schneller, T.; Bttger, U. [Institut fr Werkstoffe der Elektrotechnik 2, RWTH Aachen University, Sommerfeldstrae 24, D-52074 Aachen (Germany); Waser, R. [Institut fr Werkstoffe der Elektrotechnik 2, RWTH Aachen University, Sommerfeldstrae 24, D-52074 Aachen (Germany); Peter Grnberg Institut 7, Forschungszentrum Jlich GmbH, D-52425 Jlich (Germany)

2014-05-19T23:59:59.000Z

64

Union Carbides 20 years in nuclear energy, part 2  

NLE Websites -- All DOE Office Websites (Extended Search)

magnetic separators were discontinued December 23, 1946, as production units. "1947 - Carbide Carbon Chemical Company replaced Tennessee Eastman Corporation as the operating...

65

Radiation effects on the electrical properties of hafnium oxide based MOS capacitors.  

SciTech Connect

Hafnium oxide-based MOS capacitors were investigated to determine electrical property response to radiation environments. In situ capacitance versus voltage measurements were analyzed to identify voltage shifting as a result of changes to trapped charge with increasing dose of gamma, neutron, and ion radiation. In situ measurements required investigation and optimization of capacitor fabrication to include dicing, cleaning, metalization, packaging, and wire bonding. A top metal contact of 200 angstroms of titanium followed by 2800 angstroms of gold allowed for repeatable wire bonding and proper electrical response. Gamma and ion irradiations of atomic layer deposited hafnium oxide on silicon devices both resulted in a midgap voltage shift of no more than 0.2 V toward less positive voltages. This shift indicates recombination of radiation induced positive charge with negative trapped charge in the bulk oxide. Silicon ion irradiation caused interface effects in addition to oxide trap effects that resulted in a flatband voltage shift of approximately 0.6 V also toward less positive voltages. Additionally, no bias dependent voltage shifts with gamma irradiation and strong oxide capacitance room temperature annealing after ion irradiation was observed. These characteristics, in addition to the small voltage shifts observed, demonstrate the radiation hardness of hafnium oxide and its applicability for use in space systems.

Petrosky, J. C. (Air Force Institute of Technology, Wright-Patterson Air Force Base, OH); McClory, J. W. (Air Force Institute of Technology, Wright-Patterson Air Force Base, OH); Bielejec, Edward Salvador; Foster, J. C. (Air Force Institute of Technology, Wright-Patterson Air Force Base, OH)

2010-10-01T23:59:59.000Z

66

On the phase formation of sputtered hafnium oxide and oxynitride films  

SciTech Connect

Hafnium oxynitride films are deposited from a Hf target employing direct current magnetron sputtering in an Ar-O{sub 2}-N{sub 2} atmosphere. It is shown that the presence of N{sub 2} allows for the stabilization of the transition zone between the metallic and the compound sputtering mode enabling deposition of films at well defined conditions of target coverage by varying the O{sub 2} partial pressure. Plasma analysis reveals that this experimental strategy facilitates control over the flux of the O{sup -} ions which are generated on the oxidized target surface and accelerated by the negative target potential toward the growing film. An arrangement that enables film growth without O{sup -} ion bombardment is also implemented. Moreover, stabilization of the transition sputtering zone and control of the O{sup -} ion flux without N{sub 2} addition is achieved employing high power pulsed magnetron sputtering. Structural characterization of the deposited films unambiguously proves that the phase formation of hafnium oxide and hafnium oxynitride films with the crystal structure of HfO{sub 2} is independent from the O{sup -} bombardment conditions. Experimental and theoretical data indicate that the presence of vacancies and/or the substitution of O by N atoms in the nonmetal sublattice favor the formation of the cubic and/or the tetragonal HfO{sub 2} crystal structure at the expense of the monoclinic HfO{sub 2} one.

Sarakinos, K.; Music, D.; Mraz, S.; Baben, M. to; Jiang, K.; Nahif, F.; Braun, A.; Zilkens, C.; Schneider, J. M. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 16, D-52056 Aachen (Germany); Konstantinidis, S. [Laboratoire de Chimie Inorganique et Analytique, Universite de Mons, Avenue Copernic 1, 7000 Mons (Belgium); Renaux, F.; Cossement, D. [Materia Nova Research Center, Avenue Copernic 1, 7000 Mons (Belgium); Munnik, F. [Forschungszentrum Dresden Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany)

2010-07-15T23:59:59.000Z

67

Transient analysis of silicon carbide power MOSFET.  

E-Print Network (OSTI)

??This thesis illustrates the transient performance of Silicon carbide (4H-SiC) Power MOSFET. Transient analysis enables the designer to understand the thermal stress the semiconductor device (more)

Pushpakaran, Bejoy

2012-01-01T23:59:59.000Z

68

Modelling Precipitation of Carbides in Martensitic Steels  

E-Print Network (OSTI)

embrittlement is one of the major factors responsible for failure. It is believed that carbide particles can act as hydrogen trapping sites, thus reducing the risk of embrittlement. The thesis begins with a review of the physical metallurgy of secondary...

Yamasaki, Shingo

69

Silver transport in CVD silicon carbide  

E-Print Network (OSTI)

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 ...

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

2004-01-01T23:59:59.000Z

70

Electroextraction of boron from boron carbide scrap  

SciTech Connect

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.

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

71

Silicon Carbide Power Semiconductor Devices in the Cleanroom...  

NLE Websites -- All DOE Office Websites (Extended Search)

Silicon Carbide Power Semiconductor Devices in the Cleanroom Silicon Carbide Power Semiconductor Devices in the Cleanroom Ron Olson 2012.10.04 I would like to introduce Zach Stum,...

72

Making Silicon Carbide Devices in the Cleanroom | GE Global Research  

NLE Websites -- All DOE Office Websites (Extended Search)

Silicon Carbide Devices in the Cleanroom Making Silicon Carbide Devices in the Cleanroom Ron Olson 2012.08.23 As the Wide Bandgap Process and Fab manager for the GE Global Research...

73

Silicon Carbides in the Cleanroom | GE Global Research  

NLE Websites -- All DOE Office Websites (Extended Search)

Clean Room: Silicon Carbides GE Global Research is working on nanoscale silicon carbide devices. Find out what we're doing. You Might Also Like 2-1-10-v-working-at-ge-resear...

74

Temperature Dependent Pspice Model of Silicon Carbide Power MOSFET  

E-Print Network (OSTI)

Temperature Dependent Pspice Model of Silicon Carbide Power MOSFET Yutian Cui1 Madhu Chinthavali2-- This paper provides a behavioral model in Pspice for a silicon carbide (SiC) power MOSFET rated at 1200 V

Tolbert, Leon M.

75

Lithium carbide is prospective material for breeder of fusion reactor  

Science Journals Connector (OSTI)

It is shown that lithium carbide is a prospective material for breeder of fusion reactor. The lithium carbide equivalent dose rate reaches...?5...Sv/h) one minute after the irradiation with fusion reactor neutron...

M. V. Alenina; V. P. Kolotov; Yu. M. Platov

2014-03-01T23:59:59.000Z

76

Deposition method for producing silicon carbide high-temperature semiconductors  

DOE Patents (OSTI)

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.

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

1987-01-01T23:59:59.000Z

77

Carbides composite surface layers produced by (PTA)  

SciTech Connect

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.

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

78

Joining of porous silicon carbide bodies  

DOE Patents (OSTI)

A method of joining two porous bodies of silicon carbide is disclosed. It entails utilizing an aqueous slip of a similar silicon carbide as was used to form the porous bodies, including the sintering aids, and a binder to initially join the porous bodies together. Then the composite structure is subjected to cold isostatic pressing to form a joint having good handling strength. Then the composite structure is subjected to pressureless sintering to form the final strong bond. Optionally, after the sintering the structure is subjected to hot isostatic pressing to further improve the joint and densify the structure. The result is a composite structure in which the joint is almost indistinguishable from the silicon carbide pieces which it joins.

Bates, Carl H. (Worcester, MA); Couhig, John T. (Worcester, MA); Pelletier, Paul J. (Thompson, CT)

1990-05-01T23:59:59.000Z

79

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

E-Print Network (OSTI)

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 for the overall transformation kinetics of niobium carbide precipitation in austenite that takes into account

Cambridge, University of

80

Master Thesis: Simulation of plastic deformation in cemented carbide inserts  

E-Print Network (OSTI)

Master Thesis: Simulation of plastic deformation in cemented carbide inserts Background Sandvik in cemented carbide, high-speed steel and other hard materials such as diamond, cubic boron nitride in cemented carbide inserts will be performed using the FEM software Ansys and AdvantEdge. The work

Haviland, David

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Laser Ablation Synthesis and Optical Characterization of Silicon Carbide Nanowires  

E-Print Network (OSTI)

Laser Ablation Synthesis and Optical Characterization of Silicon Carbide Nanowires Wensheng Shi Kong, SAR, China Silicon carbide (SiC) nanowires were synthesized at 900°C by the laser ablation and composite nanostructures,4 have been fabricated by this technique. Silicon carbide (SiC) is a wide

Zheng, Yufeng

82

PECVD Silicon Carbide Waveguides for Multichannel G. Pandraud  

E-Print Network (OSTI)

PECVD Silicon Carbide Waveguides for Multichannel Sensors G. Pandraud Kavli Institute of Nano Deposition (PECVD) Silicon Carbide (SiC) waveguides. Thin SiC films have been deposited onto Si substrates with a SiO2 film acting as a cladding layer around the carbide core. In the sensor, the evanescent tale

Technische Universiteit Delft

83

Filament velocity scaling laws for warm ions  

SciTech Connect

The dynamics of filaments or blobs in the scrape-off layer of magnetic fusion devices are studied by magnitude estimates of a comprehensive drift-interchange-Alfvn fluid model. The standard blob models are reproduced in the cold ion case. Even though usually neglected, in the scrape-off layer, the ion temperature can exceed the electron temperature by an order of magnitude. The ion pressure affects the dynamics of filaments amongst others by adding up to the interchange drive and the polarisation current. It is shown how both effects modify the scaling laws for filament velocity in dependence of its size. Simplifications for experimentally relevant limit regimes are given. These are the sheath dissipation, collisional, and electromagnetic regime.

Manz, P. [Physik-Department E28, Technische Universitt Mnchen, James-Franck-Str. 1, 85748 Garching (Germany) [Physik-Department E28, Technische Universitt Mnchen, James-Franck-Str. 1, 85748 Garching (Germany); Max-Planck-Institut fr Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Carralero, D.; Birkenmeier, G.; Mller, H. W.; Scott, B. D. [Max-Planck-Institut fr Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany)] [Max-Planck-Institut fr Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Mller, S. H. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego 92093 (United States)] [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego 92093 (United States); Fuchert, G. [Insitut fr Grenzflchenverfahrenstechnik und Plasmatechnologie, Universitt Stuttgart, 70569 Stuttgart (Germany)] [Insitut fr Grenzflchenverfahrenstechnik und Plasmatechnologie, Universitt Stuttgart, 70569 Stuttgart (Germany); Stroth, U. [Max-Planck-Institut fr Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany) [Max-Planck-Institut fr Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Physik-Department E28, Technische Universitt Mnchen, James-Franck-Str. 1, 85748 Garching (Germany)

2013-10-15T23:59:59.000Z

84

Reconnection of vortex filaments and Kolmogorov spectrum  

E-Print Network (OSTI)

The energy spectrum of the 3D velocity field, induced by collapsing vortex filaments is studied. One of the aims of this work is to clarify the appearance of the Kolmogorov type energy spectrum $E(k)\\varpropto k^{-5/3}$, observed in many numerical works on discrete vortex tubes (quantized vortex filaments in quantum fluids). Usually, explaining classical turbulent properties of quantum turbulence, the model of vortex bundles, is used. This model is necessary to mimic the vortex stretching, which is responsible for the energy transfer in classical turbulence. In our consideration we do not appeal to the possible "bundle arrangement" but explore alternative idea that the turbulent spectra appear from singular solution, which describe the collapsing line at moments of reconnection. One more aim is related to an important and intensively discussed topic - a role of hydrodynamic collapse in the formation of turbulent spectra. We demonstrated that the specific vortex filament configuration generated the spectrum $E...

Nemirovskii, Sergey K

2014-01-01T23:59:59.000Z

85

Infrared Radiation Filament And Metnod Of Manufacture  

DOE Patents (OSTI)

An improved IR radiation source is provided by the invention. A radiation filament has a textured surface produced by seeded ion bombardment of a metal foil which is cut to a serpentine shape and mounted in a windowed housing. Specific ion bombardment texturing techniques tune the surface to maximize emissions in the desired wavelength range and to limit emissions outside that narrow range, particularly at longer wavelengths. A combination of filament surface texture, thickness, material, shape and power circuit feedback control produce wavelength controlled and efficient radiation at much lower power requirements than devices of the prior art.

Johnson, Edward A. (Bedford, MA)

1998-11-17T23:59:59.000Z

86

High Q silicon carbide microdisk resonator  

SciTech Connect

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.

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

87

Prealloyed catalyst for growing silicon carbide whiskers  

DOE Patents (OSTI)

A prealloyed metal catalyst is used to grow silicon carbide whiskers, especially in the .beta. form. Pretreating the metal particles to increase the weight percentages of carbon or silicon or both carbon and silicon allows whisker growth to begin immediately upon reaching growth temperature.

Shalek, Peter D. (Los Alamos, NM); Katz, Joel D. (Niagara Falls, NY); Hurley, George F. (Los Alamos, NM)

1988-01-01T23:59:59.000Z

88

PWR cores with silicon carbide cladding  

SciTech Connect

The feasibility of using silicon carbide rather than Zircaloy cladding, to reach higher power levels and higher discharge burnups in PWRs has been evaluated. A preliminary fuel design using fuel rods with the same dimensions as in the Westinghouse Robust Fuel Assembly but with fuel pellets having 10 vol% central void has been adopted to mitigate the higher fuel temperatures that occur due to the lower thermal conductivity of the silicon carbide and to the persistence of the open clad-pellet gap over most of the fuel life. With this modified fuel design, it is possible to achieve 18 month cycles that meet present-day operating constraints on peaking factor, boron concentration, reactivity coefficients and shutdown margin, while allowing batch average discharge burnups up to 80 MWD/kgU and peak rod burnups up to 100 MWD/kgU. Power uprates of 10% and possibly 20% also appear feasible. For non-uprated cores, the silicon carbide-clad fuel has a clear advantage that increases with increasing discharge burnup. Even for comparable discharge burnups, there is a savings in enriched uranium. Control rod configuration modifications may be required to meet the shutdown margin criterion for the 20% up-rate. Silicon carbide's ability to sustain higher burnups than Zircaloy also allows the design of a licensable two year cycle with only 96 fresh assemblies, avoiding the enriched uranium penalty incurred with use of larger batch sizes due to their excessive leakage. (authors)

Dobisesky, J. P.; Carpenter, D.; Pilat, E.; Kazimi, M. S. [Center for Advanced Nuclear Energy Systems, Dept. of Nuclear Science and Engineering, Massachusetts Inst. of Technology, 77 Massachusetts Avenue 24-215, Cambridge, MA 02139-4307 (United States)

2012-07-01T23:59:59.000Z

89

16 - Applications of Refractory Carbides and Nitrides  

Science Journals Connector (OSTI)

Publisher Summary This chapter reviews the applications of refractory carbides and nitrides in each of the following industrial categories: (1) automotive and aerospace, (2) industrial machinery and equipment, (3) cutting and grinding tools, (4) armor, (5) nuclear, (6) semiconductor, and (6) optical. Many of the automotive and aerospace applications of refractory carbides and nitrides are of a structural and chemical nature, especially in applications involving high temperature and/or corrosive environments where most metals are no longer suitable. These applications are usually in the bulk form and are made possible by recent advances in processing technology. Relatively large parts can now be produced to near-net shape with little machining required. Applications of refractory carbides and nitrides are found extensively in machinery and equipment for protection against wear, erosion, and chemical attack. Both bulk materials and coatings are used. The most important bulk material is tungsten carbide sintered with a metallic binder that is usually cobalt. Cutting and grinding tools are a special case of wear and corrosion applications. Cutting tools have a sharp edge for the purpose of shaving and generating a material chip. This edge must remain sharp for the tool to perform properly. Grinding tools are different in that they have an abrasive-coated surface that generates a powder as opposed to the chip of a cutting tool.

Hugh O. Pierson

1996-01-01T23:59:59.000Z

90

Process for coating tungsten carbide with cobalt metal  

SciTech Connect

A process is described for coating tungsten carbide with cobalt metal, the process comprising: (a) forming an aqueous slurry of tungsten carbide having a particle size of no greater than - 100 mesh, and zinc metal powder; (b) adding ammonia to the slurry with the amount of the ammonia being sufficient so that the slurry is basic after the subsequent addition of cobalt chloride in step c; (c) adding to the resulting ammoniated slurry, a solution of cobalt chloride with agitation, to form a coating of partially reduced cobalt on the tungsten carbide; (d) removing the resulting cobalt coated tungsten carbide from the resulting liquor; and (e) heating the cobalt coated tungsten carbide in a reducing atmosphere to effect the essentially complete reduction of the cobalt and to produce a cobalt metal coating on the tungsten carbide, the coating making up no greater than about 15% of weight of the tungsten carbide.

Ritsko, J.E.; Lee, J.S.

1989-01-31T23:59:59.000Z

91

Processing and properties of extruded tungsten-hafnium and tungsten-steel composites  

SciTech Connect

The purpose of this study was to evaluate the processing behavior and properties of tungsten-hafnium (W-Hf) and W-steel composites produced by hot extrusion of canned powders. The W-Hf composite was consolidated by extrusion of blended powders with preheat temperatures over the temperature range of 1100 to 1400{degrees}C. All extrusions produced fully dense material which exhibits elongation of the tungsten phase within the hafnium matrix. The flow stress, as characterized by the extrusion constant, decreases with increasing temperature up to 1300{degrees}C and increases substantially at 1400{degrees}C as significant quantities of intermetallic phase are formed during preheating. The room-temperature (RT) hardness and compressive yield stress increase modestly with increased extrusion ratio and are not affected by extrusion temperature in the range 1100 to 1300{degrees}C. The microstructures are essentially fully recrystallized at the 1300{degrees}C preheat temperature and partially recrystallized at lower temperatures. Additionally, a mixture of tungsten and steel powder was consolidated to full density by hot extrusion at a 1000{degrees}C preheat temperature and a reduction ratio of 4.2. Increased reduction of the W-steel composite results in increased RT hardness.

Ohriner, E.K.; Sikka, V.K. [Oak Ridge National Lab., TN (United States); Kapoor, D. [Army Armament Research and Development Engineering Center, Dover, NJ (United States)

1995-02-01T23:59:59.000Z

92

Dynamics of filament formation in a Kerr medium  

SciTech Connect

We have studied the large-scale beam breakup and filamentation of femtosecond pulses in a Kerr medium. We have experimentally monitored the formation of stable light filaments, conical emission, and interactions between filaments. Three major stages lead to the formation of stable light filaments: First the beam breaks up into a pattern of connected lines (constellation), then filaments form on the constellations, and finally the filaments release a fraction of their energy through conical emission. We observed a phase transition to a faster filamentation rate at the onset of conical emission. We attribute this to the interaction of conical emissions with the constellation which creates additional filaments. Numerical simulations show good agreement with the experimental results.

Centurion, Martin [Physics Department, California Institute of Technology, Pasadena, California 91125 (United States); Pu Ye; Tsang, Mankei; Psaltis, Demetri [Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125 (United States)

2005-06-15T23:59:59.000Z

93

Dynamics of filament formation in a Kerr medium  

Science Journals Connector (OSTI)

We have studied the large-scale beam breakup and filamentation of femtosecond pulses in a Kerr medium. We have experimentally monitored the formation of stable light filaments, conical emission, and interactions between filaments. Three major stages lead to the formation of stable light filaments: First the beam breaks up into a pattern of connected lines (constellation), then filaments form on the constellations, and finally the filaments release a fraction of their energy through conical emission. We observed a phase transition to a faster filamentation rate at the onset of conical emission. We attribute this to the interaction of conical emissions with the constellation which creates additional filaments. Numerical simulations show good agreement with the experimental results.

Martin Centurion; Ye Pu; Mankei Tsang; Demetri Psaltis

2005-06-17T23:59:59.000Z

94

Filamentation Time Diagnosis of Thinning Troughs and Cutoff Lows  

Science Journals Connector (OSTI)

This paper analyzes synoptic-scale trough-thinning processes using a filamentation time diagnostic. The filamentation time diagnostic is derived from the potential vorticity equation expressed in spherical coordinates in the horizontal plane and ...

Yu-Ming Tsai; Hung-Chi Kuo; Wayne H. Schubert

2010-06-01T23:59:59.000Z

95

Submesoscale Cold Filaments in the Gulf Stream  

Science Journals Connector (OSTI)

A set of realistic, very high-resolution simulations is made for the Gulf Stream region using the oceanic model Regional Oceanic Modeling System (ROMS) to study the life cycle of the intense submesoscale cold filaments that form on the subtropical ...

Jonathan Gula; M. Jeroen Molemaker; James C. McWilliams

2014-10-01T23:59:59.000Z

96

Light sources based on semiconductor current filaments  

DOE Patents (OSTI)

The present invention provides a new type of semiconductor light source that can produce a high peak power output and is not injection, e-beam, or optically pumped. The present invention is capable of producing high quality coherent or incoherent optical emission. The present invention is based on current filaments, unlike conventional semiconductor lasers that are based on p-n junctions. The present invention provides a light source formed by an electron-hole plasma inside a current filament. The electron-hole plasma can be several hundred microns in diameter and several centimeters long. A current filament can be initiated optically or with an e-beam, but can be pumped electrically across a large insulating region. A current filament can be produced in high gain photoconductive semiconductor switches. The light source provided by the present invention has a potentially large volume and therefore a potentially large energy per pulse or peak power available from a single (coherent) semiconductor laser. Like other semiconductor lasers, these light sources will emit radiation at the wavelength near the bandgap energy (for GaAs 875 nm or near infra red). Immediate potential applications of the present invention include high energy, short pulse, compact, low cost lasers and other incoherent light sources.

Zutavern, Fred J. (Albuquerque, NM); Loubriel, Guillermo M. (Albuquerque, NM); Buttram, Malcolm T. (Sandia Park, NM); Mar, Alan (Albuquerque, NM); Helgeson, Wesley D. (Albuquerque, NM); O'Malley, Martin W. (Edgewood, NM); Hjalmarson, Harold P. (Albuquerque, NM); Baca, Albert G. (Albuquerque, NM); Chow, Weng W. (Cedar Crest, NM); Vawter, G. Allen (Albuquerque, NM)

2003-01-01T23:59:59.000Z

97

Flagellar Movement: A Sliding Filament Model  

Science Journals Connector (OSTI)

...sinus-oidal waves such as those which can be produced on a vibrating string. The bends, or bent regions, of the bendina waves have...demonstrated that the propa--ated waves which can be generated by oscillating one end of a passive elastic filament immersed in a viscous...

Charles J. Brokaw

1972-11-03T23:59:59.000Z

98

Diamond-silicon carbide composite and method  

DOE Patents (OSTI)

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.

Zhao, Yusheng (Los Alamos, NM)

2011-06-14T23:59:59.000Z

99

Tailoring the index of refraction of nanocrystalline hafnium oxide thin films  

SciTech Connect

Hafnium oxide (HfO{sub 2}) films were grown by sputter-deposition by varying the growth temperature (T{sub s}?=?25700?C). HfO{sub 2} films grown at T{sub s}?

Vargas, Mirella [Department of Metallurgical and Materials Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)] [Department of Metallurgical and Materials Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States); Murphy, N. R. [Materials and Manufacturing Directorate (RX), 3005 Hobson Way, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio 45433 (United States)] [Materials and Manufacturing Directorate (RX), 3005 Hobson Way, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio 45433 (United States); Ramana, C. V., E-mail: rvchintalapalle@utep.edu [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)

2014-03-10T23:59:59.000Z

100

Wake-up effects in Si-doped hafnium oxide ferroelectric thin films  

SciTech Connect

Hafnium oxide based ferroelectric thin films have shown potential as a promising alternative material for non-volatile memory applications. This work reports the switching stability of a Si-doped HfO{sub 2} film under bipolar pulsed-field operation. High field cycling causes a wake-up in virgin pinched polarization hysteresis loops, demonstrated by an enhancement in remanent polarization and a shift of negative coercive voltage. The rate of wake-up is accelerated by either reducing the frequency or increasing the amplitude of the cycling field. We suggest de-pinning of domains due to reduction of the defect concentration at bottom electrode interface as origin of the wake-up.

Zhou, Dayu, E-mail: zhoudayu@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China) [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Key Laboratory for Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024 (China); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Xu, Jin [Department of Electronic Engineering, Dalian Neusoft University of Information, Dalian 116023 (China)] [Department of Electronic Engineering, Dalian Neusoft University of Information, Dalian 116023 (China); Li, Qing; Guan, Yan [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)] [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Cao, Fei; Dong, Xianlin [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)] [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Mller, Johannes [Fraunhofer IPMS-CNT, Koengisbruecker Strasse 180, 01109 Dresden (Germany)] [Fraunhofer IPMS-CNT, Koengisbruecker Strasse 180, 01109 Dresden (Germany); Schenk, Tony; Schrder, Uwe [Namlab gGmbH/TU Dresden, Noethnitzer Strasse 64, 01187 Dresden (Germany)] [Namlab gGmbH/TU Dresden, Noethnitzer Strasse 64, 01187 Dresden (Germany)

2013-11-04T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

High-k (k=30) amorphous hafnium oxide films from high rate room temperature deposition  

SciTech Connect

Amorphous hafnium oxide (HfO{sub x}) is deposited by sputtering while achieving a very high k{approx}30. Structural characterization suggests that the high k is a consequence of a previously unreported cubiclike short range order in the amorphous HfO{sub x} (cubic k{approx}30). The films also possess a high electrical resistivity of 10{sup 14} {Omega} cm, a breakdown strength of 3 MV cm{sup -1}, and an optical gap of 6.0 eV. Deposition at room temperature and a high deposition rate ({approx}25 nm min{sup -1}) makes these high-k amorphous HfO{sub x} films highly advantageous for plastic electronics and high throughput manufacturing.

Li, Flora M.; Bayer, Bernhard C.; Hofmann, Stephan; Milne, William I.; Flewitt, Andrew J. [Department of Engineering, Electrical Engineering Division, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Dutson, James D.; Wakeham, Steve J.; Thwaites, Mike J. [Plasma Quest Ltd., Unit 1B, Rose Estate, Osborn Way, Hook, Hampshire RG27 9UT (United Kingdom)

2011-06-20T23:59:59.000Z

102

Boron-carbide-aluminum and boron-carbide-reactive metal cermets  

DOE Patents (OSTI)

Hard, tough, lightweight 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 consolidation step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modulus of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi.sqroot.in. These composites and methods can be used to form a variety of structural elements.

Halverson, Danny C. (Manteca, CA); Pyzik, Aleksander J. (Seattle, WA); Aksay, Ilhan A. (Seattle, WA)

1986-01-01T23:59:59.000Z

103

Design of duplex low-carbon steels with carbide forming elements  

E-Print Network (OSTI)

Molybdenum X3 a strong carbide forming element MoC). (in the form of alloy carbides. Molybdenum improves grain1) Niobium is a strong carbide forming element (NbC). The

Costello, Peter K.

2012-01-01T23:59:59.000Z

104

Laser Processing of Refractory Metal - Refractory Carbide Alloys.  

E-Print Network (OSTI)

??The objective of the present study was to laser process a refractory metal refractory carbide alloy based on W-Ti-C ternary system for severe service (more)

Rajput, Deepak

2008-01-01T23:59:59.000Z

105

Plasma Filamentation in the Rijnhuizen Tokamak RTP  

Science Journals Connector (OSTI)

Evidence for small scale magnetic structures in the Rijnhuizen tokamak RTP is presented. These are manifest through steps and peaks in the electron temperature and pressure, measured with multiposition Thomson scattering. During central electron cyclotron heating, several filaments of high pressure are found in the power deposition region. They live hundreds of microseconds. Near the sawtooth inversion radius a "step" in the temperature profile occurs. Further out, quasiperiodic structures are observed, in both Ohmic and heated discharges.

N. J. Lopes Cardozo; F. C. Schller; C. J. Barth; C. C. Chu; F. J. Pijper; J. Lok; A. A. M. Oomens

1994-07-11T23:59:59.000Z

106

Acceleration and vortex filaments in turbulence  

E-Print Network (OSTI)

We report recent results from a high resolution numerical study of fluid particles transported by a fully developed turbulent flow. Single particle trajectories were followed for a time range spanning more than three decades, from less than a tenth of the Kolmogorov time-scale up to one large-eddy turnover time. We present some results concerning acceleration statistics and the statistics of trapping by vortex filaments.

F. Toschi; L. Biferale; G. Boffetta; A. Celani; B. J. Devenish; A. Lanotte

2005-01-23T23:59:59.000Z

107

Reconnection of vortex filaments and Kolmogorov spectrum  

E-Print Network (OSTI)

The energy spectrum of the 3D velocity field, induced by collapsing vortex filaments is studied. One of the aims of this work is to clarify the appearance of the Kolmogorov type energy spectrum $E(k)\\varpropto k^{-5/3}$, observed in many numerical works on discrete vortex tubes (quantized vortex filaments in quantum fluids). Usually, explaining classical turbulent properties of quantum turbulence, the model of vortex bundles, is used. This model is necessary to mimic the vortex stretching, which is responsible for the energy transfer in classical turbulence. In our consideration we do not appeal to the possible "bundle arrangement" but explore alternative idea that the turbulent spectra appear from singular solution, which describe the collapsing line at moments of reconnection. One more aim is related to an important and intensively discussed topic - a role of hydrodynamic collapse in the formation of turbulent spectra. We demonstrated that the specific vortex filament configuration generated the spectrum $E(k)$ close to the Kolmogorov dependence and discussed the reason for this as well as the reason for deviation. We also discuss the obtained results from point of view of the both classical and quantum turbulence.

Sergey K. Nemirovskii

2014-04-19T23:59:59.000Z

108

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

NLE Websites -- All DOE Office Websites (Extended Search)

Nanocrystalline 3C Silicon Carbide to Heavy-Ion Irradiation. Response of Nanocrystalline 3C Silicon Carbide to Heavy-Ion Irradiation. Abstract: Nanostructured materials are...

109

E-Print Network 3.0 - americium carbides Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

The internal... have revealed numerous internal grains, mainly refractory carbides (TiC) but also a number of rare... phases such as kamacite, taenite, iron carbide...

110

E-Print Network 3.0 - advanced silicon carbide Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

Carnegie Mellon University Collection: Materials Science 26 3 Carbide Precipitation Carbides are largely responsible for the commercial failure of many of the early Summary:...

111

Preparation and electrocatalytic activity of tungsten carbide and titania nanocomposite  

SciTech Connect

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.

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

112

Potential of Silicon Carbide-Derived Carbon for Carbon Capture  

Science Journals Connector (OSTI)

Potential of Silicon Carbide-Derived Carbon for Carbon Capture ... In contrast to conventional carbons made from natural precursors, carbide derived carbons (CDCs),(8, 10-13) being synthesized from an inorganic source, have no polar functional groups and are composed of purely covalently bonded carbon. ...

S. K. Bhatia; T. X. Nguyen

2011-08-08T23:59:59.000Z

113

Molybdenum disilicide composites reinforced with zirconia and silicon carbide  

DOE Patents (OSTI)

Compositions 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.

Petrovic, John J. (Los Alamos, NM)

1995-01-01T23:59:59.000Z

114

The chemical vapor deposition of zirconium carbide onto ceramic substrates  

SciTech Connect

Zirconium carbide is an attractive ceramic material due to its unique properties such as high melting point, good thermal conductivity, and chemical resistance. The controlled preparation of zirconium carbide films of superstoichiometric, stoichiometric, and substoichiometric compositions has been achieved utilizing zirconium tetrachloride and methane precursor gases in an atmospheric pressure high temperature chemical vapor deposition system.

Glass, John A, Jr.; Palmisiano, Nick, Jr.; Welsh, R. Edward

1999-07-01T23:59:59.000Z

115

Nanostructured Molybdenum Carbide: Sonochemical Synthesis and Catalytic Properties  

E-Print Network (OSTI)

to be a useful technique to generate nanophase transition metals.7,8 Recently, molybdenum and tungsten carbides of metal salts.5,6 Sonochemical decomposition of transition metal carbonyl compounds has also been provenNanostructured Molybdenum Carbide: Sonochemical Synthesis and Catalytic Properties Taeghwan Hyeon

Suslick, Kenneth S.

116

Molybdenum disilicide composites reinforced with zirconia and silicon carbide  

DOE Patents (OSTI)

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.

Petrovic, J.J.

1995-01-17T23:59:59.000Z

117

Mechanism of Actin Filament Bundling by Fascin  

SciTech Connect

Fascin is the main actin filament bundling protein in filopodia. Because of the important role filopodia play in cell migration, fascin is emerging as a major target for cancer drug discovery. However, an understanding of the mechanism of bundle formation by fascin is critically lacking. Fascin consists of four {beta}-trefoil domains. Here, we show that fascin contains two major actin-binding sites, coinciding with regions of high sequence conservation in {beta}-trefoil domains 1 and 3. The site in {beta}-trefoil-1 is located near the binding site of the fascin inhibitor macroketone and comprises residue Ser-39, whose phosphorylation by protein kinase C down-regulates actin bundling and formation of filopodia. The site in {beta}-trefoil-3 is related by pseudo-2-fold symmetry to that in {beta}-trefoil-1. The two sites are {approx}5 nm apart, resulting in a distance between actin filaments in the bundle of {approx}8.1 nm. Residue mutations in both sites disrupt bundle formation in vitro as assessed by co-sedimentation with actin and electron microscopy and severely impair formation of filopodia in cells as determined by rescue experiments in fascin-depleted cells. Mutations of other areas of the fascin surface also affect actin bundling and formation of filopodia albeit to a lesser extent, suggesting that, in addition to the two major actin-binding sites, fascin makes secondary contacts with other filaments in the bundle. In a high resolution crystal structure of fascin, molecules of glycerol and polyethylene glycol are bound in pockets located within the two major actin-binding sites. These molecules could guide the rational design of new anticancer fascin inhibitors.

Jansen, Silvia; Collins, Agnieszka; Yang, Changsong; Rebowski, Grzegorz; Svitkina, Tatyana; Dominguez, Roberto (UPENN); (UPENN-MED)

2013-03-07T23:59:59.000Z

118

Hollow cylindrical plasma filament waveguide with discontinuous finite thickness cladding  

SciTech Connect

We have explored here a hollow cylindrical laser plasma multifilament waveguide with discontinuous finite thickness cladding, in which the separation between individual filaments is in the range of several millimeters and the waveguide cladding thickness is in the order of the microwave penetration depth. Such parameters give a closer representation of a realistic laser filament waveguide sustained by a long stable propagation of femtosecond (fs) laser pulses. We report how the waveguide losses depend on structural parameters like normalized plasma filament spacing, filament to filament distance or pitch, normal spatial frequency, and radius of the plasma filament. We found that for typical plasma parameters, the proposed waveguide can support guided modes of microwaves in extremely high frequency even with a cladding consisting of only one ring of plasma filaments. The loss of the microwave radiation is mainly caused by tunneling through the discontinuous finite cladding, i.e., confinement loss, and is weakly dependent on the plasma absorption. In addition, the analysis indicates that the propagation loss is fairly large compared with the loss of a plasma waveguide with a continuous infinite thickness cladding, while they are comparable when using a cladding contains more than one ring. Compared to free space propagation, this waveguide still presents a superior microwave transmission to some distance in the order of the filamentation length; thus, the laser plasma filaments waveguide may be a potential channel for transporting pulsed-modulated microwaves if ensuring a long and stable propagation of fs laser pulses.

Alshershby, Mostafa; Hao Zuoqiang; Lin Jingquan [School of Science, Changchun University of Science and Technology, Changchun 130022 (China)

2013-01-15T23:59:59.000Z

119

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

SciTech Connect

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,

Quets, J.; Alford, J.R.

1999-07-01T23:59:59.000Z

120

High temperature intermetallic binders for HVOF carbides  

SciTech Connect

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.

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

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Gas phase spectroscopy of alkali carbides: The pure rotational spectrum of KC ,,X 4  

E-Print Network (OSTI)

observation of potassium carbide, and of any alkali metal carbide species. The molecule was produced under d, and possible ways to better activate C­C and C­H bonds.1 Investigating metal carbide species also can lead- faces. Finally, it has recently been suggested that adding metal carbides to H2 may provide high energy

Ziurys, Lucy M.

122

High-rate chemical vapor deposition of nanocrystalline silicon carbide films by radio frequency thermal plasma  

E-Print Network (OSTI)

High-rate chemical vapor deposition of nanocrystalline silicon carbide films by radio frequency Semiconductor, Eden Prairie, MN, USA Received 10 July 2002; accepted 14 July 2002 Abstract Silicon carbide films; Nanomaterials; Silicon carbide; Thermal plasmas; Thin films; Si tetrachlorine precursor Silicon carbide has

Zachariah, Michael R.

123

J. Am. Cerum. SOC., 72 [5] 775-80 (1989) Processingof Boron Carbide-Aluminum Composites  

E-Print Network (OSTI)

J. Am. Cerum. SOC., 72 [5] 775-80 (1989) journal Processingof Boron Carbide-Aluminum Composites, Universityof California, Livermore, California 94550 The processing problems associated with boron carbide carbide, aluminum, processing, cermets.] I. Introduction ORON CARBIDE (B4C)+is a very hard (9.5+ in Mohs

Aksay, Ilhan A.

124

Rectification of evanescent heat transfer between dielectric-coated and uncoated silicon carbide plates  

E-Print Network (OSTI)

Rectification of evanescent heat transfer between dielectric-coated and uncoated silicon carbide://jap.aip.org/authors #12;Rectification of evanescent heat transfer between dielectric-coated and uncoated silicon carbide-infinite bodies of the dielectric-coated silicon carbide and uncoated silicon carbide. The permittivity

Fan, Shanhui

125

Route to transition metal carbide nanoparticles through cyanamide and metal oxides  

SciTech Connect

We have designed an efficient route to the synthesis of transition metal carbide nanoparticles starting from an organic reagent cyanamide and transition metal oxides. Four technologically important metal carbide nanoparticles such as tungsten carbide, niobium carbide, tantalum carbide and vanadium carbide were synthesized successfully at moderate temperatures. It is found that cyanamide is an efficient carburization reagent and that the metal oxides are completely transmitted into the corresponding carbide nanoparticles. A possible mechanism is proposed to explain the results of the reaction between cyanamide and the metal oxides.

Li, P.G. [Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou 310018 (China)], E-mail: peigangiphy@yahoo.com.cn; Lei, M.; Tang, W.H. [Department of Physics, Center for Optoelectronics Materials and Devices, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou 310018 (China)

2008-12-01T23:59:59.000Z

126

Computational Studies of Physical Properties of Boron Carbide  

SciTech Connect

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.

Lizhi Ouyang

2011-09-30T23:59:59.000Z

127

Novel synthesis of hafnium oxide nanoparticles by precipitation method and its characterization  

SciTech Connect

Highlights: ? HfO{sub 2} NPs were prepared by precipitation method. ? XRD and Raman analysis revealed the presence of monoclinic phase. ? The average particle size of HfO{sub 2} NPs is 20 nm. ? The method is a simple, low cost and eco-friendly approach. -- Abstract: Hafnium oxide nanoparticles (HfO{sub 2} NPs) have been successfully synthesized by means of a novel precipitation method and were characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), UVvisible, Fourier transform infrared (FTIR) and laser Raman spectroscopy. The XRD and Raman analysis revealed the presence of pure monoclinic HfO{sub 2} NPs. FESEM image showed that the HfO{sub 2} NPs were of spherical shape with an average particle size of about 20 nm. The optical band gap of the HfO{sub 2} NPs was found to be 6.12 eV. Advantages of this method were simple and low cost of synthesis of HfO{sub 2} NPs includes the small and narrow particle size distribution.

Ramadoss, Ananthakumar; Krishnamoorthy, Karthikeyan [Nanomaterials and System Lab, Department of Mechanical System Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of)] [Nanomaterials and System Lab, Department of Mechanical System Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Kim, Sang Jae, E-mail: kimsangj@jejunu.ac.kr [Nanomaterials and System Lab, Department of Mechanical System Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Department of Mechatronics Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of)

2012-09-15T23:59:59.000Z

128

Radiofrequency conical emission from femtosecond filaments in air  

SciTech Connect

We show that the broadband conical emission associated with filaments in air extends down to the radiofrequency region. This rf emission which originates from the longitudinal oscillation of charged ions formed during filamentation is strongly enhanced by the presence of a longitudinal static electric field.

Forestier, B.; Houard, A.; Durand, M.; Andre, Y. B.; Prade, B.; Mysyrowicz, A. [Laboratoire d'Optique Appliquee, ENSTA ParisTech, CNRS UMR 7639, Ecole Polytechnique, 91761 Palaiseau (France); Dauvignac, J.-Y.; Perret, F.; Pichot, Ch. [Laboratoire d'Electronique, Antennes et Telecommunications, CNRS UMR 6071, Universite Nice-Sophia Antipolis, 250 rue Albert Einstein, 06560 Valbonne (France); Pellet, M. [Ministere de la Defense, F-00457 Armees (France)

2010-04-05T23:59:59.000Z

129

ATP Hydrolysis Stimulates Large Length Fluctuations in Single Actin Filaments  

E-Print Network (OSTI)

ATP Hydrolysis Stimulates Large Length Fluctuations in Single Actin Filaments Evgeny B. Stukalin is investigated theoretically using a stochastic model that takes into account the hydrolysis of ATP filaments. It is found that the ATP hydrolysis has a strong effect on dynamic properties of single actin

130

GALAXY SPIN ALIGNMENT IN FILAMENTS AND SHEETS: OBSERVATIONAL EVIDENCE  

SciTech Connect

The properties of galaxies are known to be affected by their environment. One important question is how their angular momentum reflects the surrounding cosmic web. We use the Sloan Digital Sky Survey to investigate the spin axes of spiral and elliptical galaxies relative to their surrounding filament/sheet orientations. To detect filaments, a marked point process with interactions (the {sup B}isous model{sup )} is used. Sheets are found by detecting 'flattened' filaments. The minor axes of ellipticals are found to be preferentially perpendicular to hosting filaments. A weak correlation is found with sheets. These findings are consistent with the notion that elliptical galaxies formed via mergers, which predominantly occurred along the filaments. The spin axis of spiral galaxies is found to align with the host filament, with no correlation between spiral spin and sheet normal. When examined as a function of distance from the filament axis, a much stronger correlation is found in the outer parts, suggesting that the alignment is driven by the laminar infall of gas from sheets to filaments. When compared with numerical simulations, our results suggest that the connection between dark matter halo and galaxy spin is not straightforward. Our results provide an important input to the understanding of how galaxies acquire their angular momentum.

Tempel, Elmo [Tartu Observatory, Observatooriumi 1, 61602 Travere (Estonia)] [Tartu Observatory, Observatooriumi 1, 61602 Travere (Estonia); Libeskind, Noam I., E-mail: elmo@to.ee, E-mail: nlibeskind@aip.de [Leibniz-Institut fr Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)

2013-10-01T23:59:59.000Z

131

Purification, Ultrastructure, and Composition of Axial Filaments from Leptospira  

Science Journals Connector (OSTI)

...typical procaryotic nuclear region. The axial filament...FILAMENTS Denton DV-502 vacuum evaporator with carbon...tetramethylethylenediamine as accelerator in 12 ml of 0.05 M...typical procaryotic nuclear region (Fig. 4...glutaraldehyde-prefixed cells this nuclear region was not apparent...

Robert K. Nauman; Stanley C. Holt; C. D. Cox

1969-04-01T23:59:59.000Z

132

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

DOE Patents (OSTI)

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.

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

133

Separation of Nuclear Fuel Surrogates from Silicon Carbide Inert Matrix  

SciTech Connect

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

Dr. Ronald Baney

2008-12-15T23:59:59.000Z

134

Vacancy Hardening and Softening in Transition Metal Carbides and Nitrides  

SciTech Connect

The effects of vacancies on mechanical properties of the transition metal carbides and nitrides are studied using the ab initio pseudopotential approach. Calculated shear elastic stiffness and electronic structures show that the vacancy produces entirely different effects on the mechanical strength of groups IVb nitrides and Vb carbides. It is found that the occupation of shear-unstable metallic dd bonding states changes essentially in an opposite way for the carbides and nitrides in the presence of vacancies, resulting in different responses to shear stress. Our study provides an atomistic understanding of the anomaly in hardness for these substoichiometric materials.

Jhi, Seung-Hoon; Louie, Steven G.; Cohen, Marvin L.; Ihm, Jisoon

2001-04-09T23:59:59.000Z

135

The extreme nonlinear optics of gases and femtosecond optical filamentation  

SciTech Connect

Under certain conditions, powerful ultrashort laser pulses can form greatly extended, propagating filaments of concentrated high intensity in gases, leaving behind a very long trail of plasma. Such filaments can be much longer than the longitudinal scale over which a laser beam typically diverges by diffraction, with possible applications ranging from laser-guided electrical discharges to high power laser propagation in the atmosphere. Understanding in detail the microscopic processes leading to filamentation requires ultrafast measurements of the strong field nonlinear response of gas phase atoms and molecules, including absolute measurements of nonlinear laser-induced polarization and high field ionization. Such measurements enable the assessment of filamentation models and make possible the design of experiments pursuing applications. In this paper, we review filamentation in gases and some applications, and discuss results from diagnostics developed at Maryland for ultrafast measurements of laser-gas interactions.

Milchberg, H. M.; Chen, Y.-H.; Cheng, Y.-H.; Jhajj, N.; Palastro, J. P.; Rosenthal, E. W.; Varma, S.; Wahlstrand, J. K.; Zahedpour, S. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)

2014-10-15T23:59:59.000Z

136

Condensation of actin filaments pushing against a barrier  

E-Print Network (OSTI)

We develop a model to describe the force generated by the polymerization of an array of parallel biofilaments. The filaments are assumed to be coupled only through mechanical contact with a movable barrier. We calculate the filament density distribution and the force-velocity relation with a mean-field approach combined with simulations. We identify two regimes: a non-condensed regime at low force in which filaments are spread out spatially, and a condensed regime at high force in which filaments accumulate near the barrier. We confirm a result previously known from other related studies, namely that the stall force is equal to N times the stall force of a single filament. In the model studied here, the approach to stalling is very slow, and the velocity is practically zero at forces significantly lower than the stall force.

K. Tsekouras; D. Lacoste; K. Mallick; J. -F. Joanny

2011-10-06T23:59:59.000Z

137

Comparison Measurements of Silicon Carbide Temperature Monitors  

SciTech Connect

As part of the efforts initiated through the Advanced Test Reactor (ATR) National Scientific User Facility (NSUF) program to make Silicon Carbide (SiC) temperature monitors available, a capability was developed at the Idaho National Laboratory (INL) to complete post-irradiation evaluations of these monitors. INL selected the resistance measurement approach for detecting peak irradiation temperature from SiC temperature monitors. To demonstrate this new capability, comparison measurements were completed by INL and Oak Ridge National Laboratory (ORNL) on identical samples subjected to identical irradiation conditions. Results reported in this paper indicate that the resistance measurement approach can yield similar peak irradiation temperatures if appropriate equipment is used and appropriate procedures are followed.

J. L. Rempe; K. G. Condie; D. L. Knudson; L. L. Snead

2010-06-01T23:59:59.000Z

138

Asymmetric twins in rhombohedral boron carbide  

SciTech Connect

Superhard materials consisting of light elements have recently received considerable attention because of their ultrahigh specific strength for a wide range of applications as structural and functional materials. However, the failure mechanisms of these materials subjected to high stresses and dynamic loading remain to be poorly known. We report asymmetric twins in a complex compound, boron carbide (B{sub 4}C), characterized by spherical-aberration-corrected transmission electron microscopy. The atomic structure of boron-rich icosahedra at rhombohedral vertices and cross-linked carbon-rich atomic chains can be clearly visualized, which reveals unusual asymmetric twins with detectable strains along the twin interfaces. This study offers atomic insights into the structure of twins in a complex material and has important implications in understanding the planar defect-related failure of superhard materials under high stresses and shock loading.

Fujita, Takeshi, E-mail: tfujita@wpi-aimr.tohoku.ac.jp; Guan, Pengfei; Madhav Reddy, K.; Hirata, Akihiko; Guo, Junjie [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Chen, Mingwei, E-mail: mwchen@wpi-aimr.tohoku.ac.jp [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)

2014-01-13T23:59:59.000Z

139

UNION CARBIDE MZALS DIVISION tiiAGARA FALLS, NEW YDRK  

Office of Legacy Management (LM)

PRELIF",INARY SURVEY 0' PRELIF",INARY SURVEY 0' ELECTRDMET iORPDF.&TiCIN UNION CARBIDE MZALS DIVISION tiiAGARA FALLS, NEW YDRK Work performed by the Health and Safety Research Division Dak Ridge National Laboratory Oak Ridge, Tennessee 37830 OAK RIDGE NATIONAL LABORATORY operated by UNION CARBIDE CORPORATION for the DEPARTMENT OF ENERGY as part of the Fornierly Utilized Sites-- Remedial Action Program ,ELECTRD?'ISi 60RPOR:TION UNiON CARBIDE METALS DIVlSIOti NiASARA FALLS, NEA YORK At the requests o f the Department of Energy (DOE, then ERDA), a preliminary survey was performed at the former Electromet Plant (cur- rently Union Carbide Corporation - Metals Division plant) in Niagara Falls, Neh' York (see Fig. l), on August 24, 1976, to assess the radio- logical status 0 f those facilities utilized under~Manhattan Engineer

140

Surface roughening in ion implanted 4H-silicon carbide  

Science Journals Connector (OSTI)

Silicon carbide (SiC) devices have the potential to yield new components with functional capabilities that far exceed components based on silicon devices. Selective doping of SiC by ion implantation is an importa...

M. A. Capano; S. Ryu; J. A. Cooper Jr.; M. R. Melloch

1999-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

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

NLE Websites -- All DOE Office Websites (Extended Search)

along with a note that he thought I might be interested in this "old "glossy" on Union Carbide." He was right and I certainly appreciated him thinking of me. I found some really...

142

Rapid WolffKishner reductions in a silicon carbide microreactor  

E-Print Network (OSTI)

WolffKishner 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 ...

Newman, Stephen G.

2014-01-01T23:59:59.000Z

143

Cryogenic optical testing of sandwich-type silicon carbide mirrors  

Science Journals Connector (OSTI)

The experimental cryogenic performance of 160-mm-diameter silicon carbide (SiC) mirrors, one of which, a 700-mm-diameter mirror, is to be used as a primary mirror of the Japanese...

Kaneda, Hidehiro; Onaka, Takashi; Kawada, Mitsunobu; Murakami, Hiroshi

2003-01-01T23:59:59.000Z

144

Carbon monoxide-silicon carbide interaction in HTGR fuel particles  

Science Journals Connector (OSTI)

The corrosion of the coating-layers of silicon carbide (SiC) by carbon monoxide (CO) was observed in irradiated Triso-coated uranium dioxide particles, used in high-temperature gas-cooled reactors, by optical ...

Kazuo Minato; Toru Ogawa; Satoru Kashimura; Kousaku Fukuda

1991-05-01T23:59:59.000Z

145

Conductive two-dimensional titanium carbide clay with high...  

NLE Websites -- All DOE Office Websites (Extended Search)

MAX phases, which comprise a .70-member family of layered, hexagonal early-transition-metal carbides and nitrides 13 . To date, all MXenes have been produced by etching MAX...

146

Production of ozone and nitrogen oxides by laser filamentation  

SciTech Connect

We have experimentally measured that laser filaments in air generate up to 10{sup 14}, 3x10{sup 12}, and 3x10{sup 13} molecules of O{sub 3}, NO, and NO{sub 2}, respectively. The corresponding local concentrations in the filament active volume are 10{sup 16}, 3x10{sup 14}, and 3x10{sup 15} cm{sup -3}, and allows efficient oxidative chemistry of nitrogen, resulting in concentrations of HNO{sub 3} in the parts per million range. The latter forming binary clusters with water, our results provide a plausible pathway for the efficient nucleation recently observed in laser filaments.

Petit, Yannick; Henin, Stefano; Kasparian, Jerome; Wolf, Jean-Pierre [GAP Biophotonics, Universite de Geneve, 20 rue de l'Ecole de Medecine, CH1211 Geneve 4 (Switzerland)

2010-07-12T23:59:59.000Z

147

Understanding the Irradiation Behavior of Zirconium Carbide  

SciTech Connect

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.

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

2013-10-11T23:59:59.000Z

148

Nanostructured carbide catalysts for the hydrogen economy  

SciTech Connect

The above quote, taken from the executive summary of the Report from the US DOE Basic Energy Sciences Workshop held August 68, 2007,[1] places in context the research carried out at the University of California, Santa Barbara, which is reported in this document. The enormous impact of heterogeneous catalysis is exemplified by the Haber process for the synthesis of ammonia, which consumes a few % of the worlds energy supply and natural gas, and feeds as many as a third of the worlds population. While there have been numerous advances in understanding the process,[2] culminating in the awarding of the Nobel Prize to Gerhard Ertl in 2007, it is interesting to note that the catalysts themselves have changed very little since they were discovered heuristically in the the early part of the 20th century. The thesis of this report is that modern materials chemistry, with all the empirical knowledge of solid state chemistry, combined with cutting edge structural tools, can help develop and better heterogeneous catalysis. The first part of this report describes research in the area of early transition metal carbides (notably of Mo and W), potentially useful catalysts for water gas shift (WGS) and related reactions of use to the hydrogen economy. Although these carbides have been known to be catalytically useful since the 1970s,[3] further use of these relatively inexpensive materials have been plagued by issues of low surface areas and ill-defined, and often unreactive surfaces, in conjunction with deactivation. We have employed for the first time, a combination of constant-wavelength and time-of-flight neutron scattering, including a total scattering analysis of the latter data, to better understand what happens in these materials, in a manner that for the first time, reveals surface graphitic carbon in these materials in a quantitative manner. Problems of preparation, surface stability, and irreversible reactivity have become manifest in this class of materials that discourage us from pursuing these materials further.

Ram Seshadri, Susannah Scott, Juergen Eckert

2008-07-21T23:59:59.000Z

149

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)

-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

Rubloff, Gary W.

150

Formation of beads-on-a-string structures during break-up of viscoelastic filaments  

E-Print Network (OSTI)

Break-up of viscoelastic filaments is pervasive in both nature and technology. If a filament is formed by placing a drop of saliva between a thumb and forefinger and is stretched, the filaments morphology close to break-up ...

Bhat, Pardeep P.

151

Spin alignment of dark matter haloes in filaments and walls  

E-Print Network (OSTI)

The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter haloes are significantly correlated with each other and with the orientation of their host structures. The shape orientation is such that the halo minor axes tend to lie perpendicular to the host structure, be it a wall or filament. The orientation of the halo spin vector is mass dependent. Low mass haloes in walls and filaments have a tendency to have their spins oriented within the parent structure, while higher mass haloes in filaments have spins that tend to lie perpendicular to the parent structure.

Miguel A. Aragn-Calvo; Rien van de Weygaert; Bernard J. T. Jones; J. M. Thijs van der Hulst

2006-10-09T23:59:59.000Z

152

Apparatus for coating and impregnating filament with resin  

DOE Patents (OSTI)

The present invention is directed to an apparatus for evenly coating and impregnating a filament with binder material. Dimension control and repeatability of the coating and impregnating characteristics are obtained with the apparatus.

Robinson, S.C.; Pollard, R.E.

1986-12-17T23:59:59.000Z

153

Ultrastructure of the capitular filaments of Penicillus dumetosus (Chlorophyceae; Siphonales)  

E-Print Network (OSTI)

ULTRASTRUCTURE OF THE CAPITULAR FILAMENTS OF PENICILLUS DUMETOSUS (CHLOROPHYCEAE; SIPHONALES) A Thesis MICHAEL DOOLEY MCKENZIE Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE August 1974 Major Subject: Oceanography ULTRASTRUCTURE OF THE CAPITULAR FILAMENTS OF PENICILLUS DUMETOSUS (CHLOROPHYCEAE; SIPHONALES) A Thesis by MICHAEL DOOLEY MCKENZIE Approved as to style and content by: (Co-Chairman of ittee...

McKenzie, Michael Dooley

1974-01-01T23:59:59.000Z

154

Top-Down Fragmentation of a Warm Dark Matter Filament  

E-Print Network (OSTI)

We present the first high-resolution n-body simulations of the fragmentation of dark matter filaments. Such fragmentation occurs in top-down scenarios of structure formation, when the dark matter is warm instead of cold. In a previous paper (Knebe et al. 2002, hereafter Paper I), we showed that WDM differs from the standard Cold Dark Matter (CDM) mainly in the formation history and large-scale distribution of low-mass haloes, which form later and tend to be more clustered in WDM than in CDM universes, tracing more closely the filamentary structures of the cosmic web. Therefore, we focus our computational effort in this paper on one particular filament extracted from a WDM cosmological simulation and compare in detail its evolution to that of the same CDM filament. We find that the mass distribution of the halos forming via fragmentation within the filament is broadly peaked around a Jeans mass of a few 10^9 Msun, corresponding to a gravitational instability of smooth regions with an overdensity contrast around 10 at these redshifts. Our results confirm that WDM filaments fragment and form gravitationally bound haloes in a top-down fashion, whereas CDM filaments are built bottom-up, thus demonstrating the impact of the nature of the dark matter on dwarf galaxy properties.

Alexander Knebe; Julien Devriendt; Brad Gibson; Joseph Silk

2003-07-28T23:59:59.000Z

155

Elasticity, strength, and toughness of single crystal silicon carbide, ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous  

E-Print Network (OSTI)

Elasticity, strength, and toughness of single crystal silicon carbide, ultrananocrystalline diamond carbide 3C-SiC , ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon

Espinosa, Horacio D.

156

Phase Behavior of Pseudobinary Precious Metal?Carbide Systems  

SciTech Connect

Transition metal carbides exhibit a variety of interesting material properties, including electrochemical stability. When combined with precious metals, Ta and W carbides have shown promise as fuel cell electrode materials; yet, the phase behavior of these precious metal?carbide systems is largely unexplored. We investigated P-M-C phase behavior with P = Pt, Pd, and Ru and M = Ta and W using composition spread thin films. We attained limited control of the deposited carbide phase through variation of the sputter atmosphere and demonstrated decreased corrosion of W?C materials with increasing C content. A high-throughput X-ray diffraction and X-ray fluorescence experiment was employed for thin film characterization, which revealed solubility of Pt, Pd, and Ru in cubic WC. Density functional calculations of the lattice parameter dependence on carbon concentration enabled the determination of carbon concentration from the X-ray data as a function of transition metal stoichiometry. Our measurement of variations in the C stoichiometry and evolution of thin film texture with transition metal composition yielded surprising results. We detail how the combination of the composition spread technique, the high-throughput thin film characterization, and the density functional modeling of ternary carbide alloys provided a deep understanding of the chemical systems.

Gregoire, John M.; Tague, Michele E.; Smith, Eva H.; Dale, Darren; DiSalvo, Francis J.; Abrua, Hctor D.; Hennig, Richard G.; van Dover, R. Bruce

2010-01-01T23:59:59.000Z

157

Abundances of presolar silicon carbide grains in primitive meteorites determined by NanoSIMS  

E-Print Network (OSTI)

Abundances of presolar silicon carbide grains in primitive meteorites determined by NanoSIMS Jemma carbide (SiC) grains estimated from their noble gas components show significant variations in even

Nittler, Larry R.

158

Ordering of carbon atoms in boron carbide structure  

SciTech Connect

Boron carbide crystals have been obtained in the entire compositional range according to the phase diagram by self-propagating high-temperature synthesis (SHS). Based on the results of X-ray diffraction investigations, the samples were characterized by the unit-cell metric and reflection half-width in the entire range of carbon concentrations. A significant spread in the boron carbide unit-cell parameters for the same carbon content is found in the data in the literature; this spread contradicts the structural concepts for covalent compounds. The SHS samples have not revealed any significant spread in the unit-cell parameters. Structural analysis suggests that the spread of parameters in the literary data is related to the unique process of ordering of carbon atoms in the boron carbide structure.

Ponomarev, V. I., E-mail: i2212@yandex.ru; Kovalev, I. D.; Konovalikhin, S. V.; Vershinnikov, V. I. [Russian Academy of Sciences, Institute of Structural Macrokinetics and Materials Science (Russian Federation)

2013-05-15T23:59:59.000Z

159

Union Carbide pursuing direct conversion of methane to ethylene  

SciTech Connect

Union Carbide has begun developing an alternative source for ethylene. If a new program is successful, Carbide will be able to supplement present sources of ethylene by direct catalytic conversion of methane. The program also will provide an alternative means for possible future production of distillate motor fuels. Most ethylene consumed today is derived from dehydrogenation of ethane or propane. These sources are becoming increasingly tight, and alternatives are being sought by most polyethylene producers. Alternative sources have been on Carbide's research agenda at least since 1969, when the possibilities of converting methane were first examined. Following the Arab oil embargo of 1974 and the subsequent crude oil and natural gas price rises, most attention turned to coal conversion, at least in the U.S. However, inherent difficulties diminished the immediate prospects for utilizing coal as a source of fuels and petrochemical feedstocks.

Haggin, J.

1988-07-04T23:59:59.000Z

160

Pulsed energy synthesis and doping of silicon carbide  

DOE Patents (OSTI)

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.

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

1995-06-20T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Pulsed energy synthesis and doping of silicon carbide  

DOE Patents (OSTI)

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.

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

162

Structure-Property Relationship in Metal Carbides and Bimetallic Alloys  

SciTech Connect

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.

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

2014-03-04T23:59:59.000Z

163

A kinetic model of diamond nucleation and silicon carbide interlayer formation during chemical vapor deposition  

E-Print Network (OSTI)

A kinetic model of diamond nucleation and silicon carbide interlayer formation during chemical February 2005 Available online 7 April 2005 Abstract The presence of thin silicon carbide intermediate of carbon atoms into the silicon carbide layer and the morphology and orientation of the diamond film

Dandy, David

164

Journal of Statistical Physics A Free Energy Model of Boron Carbide  

E-Print Network (OSTI)

Journal of Statistical Physics A Free Energy Model of Boron Carbide --Manuscript Draft-- Manuscript Number: Full Title: A Free Energy Model of Boron Carbide Article Type: SI: Dedicated to M.E. Fisher, J.K. Percus and B. Widom Keywords: boron carbide; third law; first principles; thermodynamics Corresponding

Widom, Michael

165

-carbide in Alloy Steels: First-principles Jae Hoon Jang a  

E-Print Network (OSTI)

-carbide in Alloy Steels: First-principles Assessment Jae Hoon Jang a In Gee Kim a H. K. D. H that the silicon can enhance the formation of ­carbide; the mechanism of this effect is not understood words: Steels, -carbide, cementite, silicon, tempering There are two long­established reasons for adding

Cambridge, University of

166

New Silicon Carbide Schottky-gate Bipolar Mode Field Effect Transistor (SiC SBMFET)  

E-Print Network (OSTI)

New Silicon Carbide Schottky-gate Bipolar Mode Field Effect Transistor (SiC SBMFET) without PN. In this paper, we propose a novel Schottky-gate BMFET (SBMFET) using P- type 4H Silicon-Carbide 13,41, a wide, Silicon Carbide, Field effect transistor, Simulation. I. INTRODUCTION TH E BMFET operates in bipolar mode

Kumar, M. Jagadesh

167

Carbide-Derived Carbons for Adsorptive Removal of VOCs from Air Streams  

E-Print Network (OSTI)

Carbide-Derived Carbons for Adsorptive Removal of VOCs from Air Streams References 1. USEPA Literature Results Carbide-Derived Carbons Motivation Future Research · The effect of pore size and pore size decreasing removal cost is an advancement for the industry and the environment. Carbide-derived carbons (CDCs

Das, Suman

168

Shear-band structure in ballistically tested carbide-free bainitic steels  

E-Print Network (OSTI)

Shear-band structure in ballistically tested carbide-free bainitic steels L. C. D. Fieldinga , H. K recently been commercialised, with the steel structure consisting of carbide-free, nanostructured bainitic of the carbide-free mixtures of bainitic ferrite and retained austenite. It is with this in mind that bainitic

Cambridge, University of

169

In vitro cellular responses to silicon carbide nanoparticles: impact of physico-chemical  

E-Print Network (OSTI)

1 In vitro cellular responses to silicon carbide nanoparticles: impact of physico-chemical features of Nanoparticle Research 14, 10 (2012) 1143" DOI : 10.1007/s11051-012-1143-7 #12;2 Abstract Silicon carbide, and of the oxidation state of the surface on cellular H2O2 production. Keywords silicon carbide nanoparticles, laser

Paris-Sud XI, Université de

170

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

E-Print Network (OSTI)

Structural changes induced by heavy ion irradiation in titanium silicon carbide Authors J.C. Nappéa, UMR 8609, Bât. 108, 91405 Orsay, France ABSTRACT Carbide-type ceramics, which have remarkable at high temperature. The MAX phases, and more particularly titanium silicon carbide, are distinguished

Paris-Sud XI, Université de

171

Highpressure behavior of iron carbide (Fe7C3) at inner core conditions  

E-Print Network (OSTI)

Highpressure behavior of iron carbide (Fe7C3) at inner core conditions Mainak Mookherjee,1 Yoichi at high pressures have demonstrated that Fe7C3 iron carbide is a likely candidate for the Earth's inner behavior of iron carbide (Fe7C3) at inner core conditions, J. Geophys. Res., 116, B04201, doi:10

Steinle-Neumann, Gerd

172

Nano Res. 2012, 5(12): 896902896 Fabrication of Patterned Boron Carbide Nanowires and Their  

E-Print Network (OSTI)

Nano Res. 2012, 5(12): 896­902896 Fabrication of Patterned Boron Carbide Nanowires Large-area patterned boron carbide nanowires (B4C NWs) have been synthesized using chemical vapor for flexible cold cathode materials. KEYWORDS Boron carbide nanowires, patterned, field emission properties

Gao, Hongjun

173

Catalyst-Free Synthesis and Characterization of Metastable Boron Carbide Nanowires  

E-Print Network (OSTI)

Catalyst-Free Synthesis and Characterization of Metastable Boron Carbide Nanowires By Aruna Velamakanni, K. J. Ganesh, Yanwu Zhu, Paulo J. Ferreira, and Rodney S. Ruoff* 1. Introduction Boron carbide] Boroncarbidealsofindsapplicationintheaerospace industry as a rocket propellant.[4,5] Bulk boron carbide has a low fracture toughness which makes

174

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

E-Print Network (OSTI)

Towards new binary compounds: Synthesis of amorphous phosphorus carbide by pulsed laser deposition Available online 28 November 2012 Keywords: Phosphorus carbide Pulsed laser deposition X-ray photoelectron possible crystal structures of the as yet unknown phosphorus carbide as a function of composition

Bristol, University of

175

Modeling the interface area aspect ratio of carbide grains in WCCo composites  

E-Print Network (OSTI)

Modeling the interface area aspect ratio of carbide grains in WC­Co composites Xiaokun Yuan a Keywords: Cemented carbide Electron backscattered diffraction Interface area aspect ratio Five parameter analysis The average interface area aspect ratios of carbide grains in WC­Co composites are measured from

Rohrer, Gregory S.

176

Heavy Element Abundances in Presolar Silicon Carbide Grains from Low-Metallicity AGB Stars  

E-Print Network (OSTI)

Heavy Element Abundances in Presolar Silicon Carbide Grains from Low-Metallicity AGB Stars Peter explosions. Silicon carbide is the best studied presolar mineral. Based on its isotopic compositions the identified presolar minerals are diamond, silicon carbide (SiC), graphite, silicon nitride (Si3N4), corundum

177

Comments on "Effect of carbide distribution on the fracture toughness in the transition  

E-Print Network (OSTI)

Comments on "Effect of carbide distribution on the fracture toughness in the transition temperature´eriaux, UMR CNRS 7633 BP 87, 91003 Evry Cedex, France Abstract Critical cleavage stress values and carbide for the behavior of SA 508 steel. A new model based on the weakest link concept with the determined carbide size

Paris-Sud XI, Université de

178

DESIGN, MODELING, TESTING, AND SPICE PARAMETER EXTRACTION OF DIMOS TRANSISTOR IN 4H-SILICON CARBIDE  

E-Print Network (OSTI)

DESIGN, MODELING, TESTING, AND SPICE PARAMETER EXTRACTION OF DIMOS TRANSISTOR IN 4H-SILICON CARBIDE (DIMOS) transistor structure in 4H-Silicon Carbide (SiC) is presented. Simulation for transport Silicon carbide (SiC), a wide bandgap material, shows a tremendous potential for high temperature

Tolbert, Leon M.

179

Boron Carbide and Silicon Oxide Hetero-nanonecklaces via Temperature Modulation  

E-Print Network (OSTI)

Boron Carbide and Silicon Oxide Hetero-nanonecklaces via Temperature Modulation Jifa Tian, Xingjun ReceiVed April 23, 2008 ABSTRACT: Boron carbide and silicon oxide (BCSiO) hetero-nanonecklaces have been-500 nm silicon oxide nanoballs onto 20-30 nm boron carbide nanowires. Synthetic analysis shows that a two

Gao, Hongjun

180

Silicon Carbide Power Device Characterization for HEVs Burak Ozpineci1,3  

E-Print Network (OSTI)

Silicon Carbide Power Device Characterization for HEVs Burak Ozpineci1,3 burak@ieee.org Leon M: The emergence of silicon carbide- (SiC-) based power semiconductor switches, with their superior features material. Another material, silicon carbide (SiC), with superior properties compared with Si, is a good

Tolbert, Leon M.

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

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

E-Print Network (OSTI)

Microstructural changes induced by low energy heavy ion irradiation in titanium silicon carbide, and it was validated on irradiated silicon carbide. The swelling of Ti3SiC2 was estimated to 2.2 ±0 to these working conditions, non-oxide refractory ceramics are required as fuel cladding. Thus, carbides turn out

Boyer, Edmond

182

Epitaxy of Nanocrystalline Silicon Carbide on Si(111) at Room Temperature  

E-Print Network (OSTI)

Epitaxy of Nanocrystalline Silicon Carbide on Si(111) at Room Temperature Roberto Verucchi carbide (SiC) has unique chemical, physical, and mechanical properties. A factor strongly limiting Si or plastics that cannot withstand high temperatures. Silicon carbide (SiC) has unique properties that make

Alfè, Dario

183

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 lossless snubber to a design with a Silicon Carbide (SiC) diode without snubber. The theoretical of the Silicon Carbide (SiC) Schottky diodes (Infineon) changes the pictures completely. As will be detailed

184

7 Physical Model of Carbide Precipitation 2 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  

E-Print Network (OSTI)

Contents 7 Physical Model of Carbide Precipitation 2 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1 #12;Chapter 7 Physical Model of Carbide Precipitation 7.1 Introduction If the austempering process is held for prolonged periods of time precipitation of carbides from retained austenite occurs

Cambridge, University of

185

Characterization and Modeling of Silicon Carbide Power Devices and Paralleling Operation  

E-Print Network (OSTI)

Characterization and Modeling of Silicon Carbide Power Devices and Paralleling Operation Yutian Cui silicon carbide (SiC) power devices. The devices have been tested for both static and dynamic like silicon carbide (SiC) and gallium nitride (GaN) are becoming more attractive. SiC power devices

Tolbert, Leon M.

186

Effects of Silicon Carbide (SiC) Power Devices on HEV PWM Inverter Losses*  

E-Print Network (OSTI)

Effects of Silicon Carbide (SiC) Power Devices on HEV PWM Inverter Losses* Burak Ozpineci1,3 burak and Education Oak Ridge, TN 37831-0117 Abstract-The emergence of silicon carbide- (SiC-) based power, silicon carbide (SiC) with its superior properties compared with Si, is a good candidate to be used

Tolbert, Leon M.

187

DOI: 10.1002/chem.200901982 Template-Synthesized Porous Silicon Carbide as an Effective Host  

E-Print Network (OSTI)

DOI: 10.1002/chem.200901982 Template-Synthesized Porous Silicon Carbide as an Effective Host, especially those that can work more du- rably under harsh conditions. Silicon carbide (SiC) is a promising has been de- veloped for the fabrication of porous silicon carbide (SiC) by means of sin- tering

Bao, Xinhe

188

Integrated packaging allows for improvement in switching characteristics of silicon carbide devices  

E-Print Network (OSTI)

Integrated packaging allows for improvement in switching characteristics of silicon carbide devices will be available after the conference. Abstract Silicon Carbide devices can achieve very high switching speed-mode filtering). The consequences on the switching speed are discussed. 1. Introduction Silicon carbide (Si

Paris-Sud XI, Université de

189

SYSTEM IMPACT OF SILICON CARBIDE POWER DEVICES BURAK OZPINECI1,3  

E-Print Network (OSTI)

SYSTEM IMPACT OF SILICON CARBIDE POWER DEVICES BURAK OZPINECI1,3 , LEON M. TOLBERT1,2 , SYED K carbide- (SiC-) based power semiconductor switches, with their superior features compared with silicon, silicon carbide (SiC), with superior properties compared with Si, is a good candidate to be used

Tolbert, Leon M.

190

Accepted Manuscript Abundances of presolar silicon carbide grains in primitive meteorites deter-  

E-Print Network (OSTI)

Accepted Manuscript Abundances of presolar silicon carbide grains in primitive meteorites deter.R., Alexander, C.M., Orthous-Daunay, o-R., Franchi, I.A., Hoppe, P., Abundances of presolar silicon carbide of presolar silicon carbide grains in primitive meteorites determined by NanoSIMS Jemma Davidsona,1,* , Henner

Nittler, Larry R.

191

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

E-Print Network (OSTI)

Thermodynamic stability of oxide, nitride, and carbide coating materials in liquid Sn­25Li S of various oxides, carbides, and nitrides in Sn­Li is estimated as a function of lithium composition K most of the studied nitrides, carbides, and some oxides were found to be stable (DrG > 0). However

Ghoniem, Nasr M.

192

Carbon 41 (2003) 10961099 Effect of boron carbide particle addition on the  

E-Print Network (OSTI)

Carbon 41 (2003) 1096­1099 Effect of boron carbide particle addition on the thermomechanical behavior of carbon matrix silicon carbide particle composites a ,1 a , b b * ´Jorge Sanchez-Coronado , D, silicon carbide is used in combination with held at the maximum temperature for 1 h in a nitrogen carbon

Chung, Deborah D.L.

193

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

E-Print Network (OSTI)

Short- and intermediate-range structural correlations in amorphous silicon carbide: A molecular-range structural correlations in amorphous silicon carbide a-SiC are studied in terms of partial pair distributions.43.Dq, 61.43.Bn, 61.66.Dk, 81.05.Gc I. INTRODUCTION Silicon carbide SiC has been receiving increasing

Southern California, University of

194

Materials Science Forum, Vols. 426432, 2003, pp. 3542. Advances in the Kinetic Theory of Carbide Precipitation  

E-Print Network (OSTI)

Materials Science Forum, Vols. 426­432, 2003, pp. 35­42. Advances in the Kinetic Theory of Carbide Pembroke Street, Cambridge CB2 3QZ, U.K., www.msm.cam.ac.uk/phase­trans Keywords : Carbides, kinetics and reversion of carbides can determine the quality of steels. This paper is a review of efforts towards better

Cambridge, University of

195

Adhesion, stability, and bonding at metal/metal-carbide interfaces: Al/WC Donald J. Siegel  

E-Print Network (OSTI)

of adhesion between metals and transition metal carbides/nitrides based on Density Functional Theory(DFT)[14Adhesion, stability, and bonding at metal/metal-carbide interfaces: Al/WC Donald J. Siegel the nature of metal/carbide bonding. Based on the surface and interfacial free energies, we find that both

Adams, James B

196

Trends in elasticity and electronic structure of transition-metal nitrides and carbides from first principles  

E-Print Network (OSTI)

Trends in elasticity and electronic structure of transition-metal nitrides and carbides from first 2005 The elastic properties of selected transition-metal TM nitrides and carbides in B1 structure the transition-metal nitrides and carbides remain unclear and a challenge for engineering hard materials

Wu, Zhigang

197

Optical spectroscopy of tungsten carbide ,,WC... Shane M. Sickafoose, Adam W. Smith, and Michael D. Morse  

E-Print Network (OSTI)

transition-metal carbide, WC. A low-resolution scan revealed a five-member vibrational progression beginning to the isovalent molecule MoC and other transition-metal carbides. © 2002 American Institute of Physics. DOI: 10 this end, we have embarked on a study of the diatomic transition-metal carbides, and have al- ready

Morse, Michael D.

198

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

E-Print Network (OSTI)

with transition metals and yield inter- esting transition metal carbides.8­11 In a recent study12 it was reportedSynthesis, structure, and superconducting properties of tantalum carbide nanorods and nanoparticles 1997) Tantalum carbide nanorods and nanoparticles have been synthesized using a vapor-solid reaction

McHenry, Michael E.

199

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

E-Print Network (OSTI)

) that are otherwise difficult to produce (e.g., transition metal/borides, carbides, and nitrides).1,2 Many earlierCatalytically Assisted Self-Propagating High-Temperature Synthesis of Tantalum Carbide Powders Troy/carbon/tantalum carbide combustion synthesis system has been examined to determine the effects of transport agents

Wooldridge, Margaret S.

200

The growth mechanism of grain boundary carbide in Alloy 690  

SciTech Connect

The growth mechanism of grain boundary M{sub 23}C{sub 6} carbides in nickel base Alloy 690 after aging at 715 C was investigated by high resolution transmission electron microscopy. The grain boundary carbides have coherent orientation relationship with only one side of the matrix. The incoherent phase interface between M{sub 23}C{sub 6} and matrix was curved, and did not lie on any specific crystal plane. The M{sub 23}C{sub 6} carbide transforms from the matrix phase directly at the incoherent interface. The flat coherent phase interface generally lies on low index crystal planes, such as (011) and (111) planes. The M{sub 23}C{sub 6} carbide transforms from a transition phase found at curved coherent phase interface. The transition phase has a complex hexagonal crystal structure, and has coherent orientation relationship with matrix and M{sub 23}C{sub 6}: (111){sub matrix}//(0001){sub transition}//(111){sub carbide}, <112{sup }>{sub matrix}//<21{sup }10>{sub transition}//<112{sup }>{sub carbide}. The crystal lattice constants of transition phase are c{sub transition}=?(3)a{sub matrix} and a{sub transition}=?(6)/2a{sub matrix}. Based on the experimental results, the growth mechanism of M{sub 23}C{sub 6} and the formation mechanism of transition phase are discussed. - Highlights: A transition phase was observed at the coherent interfaces of M{sub 23}C{sub 6} and matrix. The transition phase has hexagonal structure, and is coherent with matrix and M{sub 23}C{sub 6}. The M{sub 23}C{sub 6} transforms from the matrix directly at the incoherent phase interface.

Li, Hui, E-mail: huili@shu.edu.cn [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Institute of Materials, Shanghai University, Shanghai 200072 (China); Xia, Shuang; Zhou, Bangxin [Institute of Materials, Shanghai University, Shanghai 200072 (China); Peng, Jianchao [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China)

2013-07-15T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride  

DOE Patents (OSTI)

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.

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

1995-01-01T23:59:59.000Z

202

Process for preparing fine grain titanium carbide powder  

DOE Patents (OSTI)

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.

Janey, Mark A. (Concord, TN)

1986-01-01T23:59:59.000Z

203

Process for forming silicon carbide films and microcomponents  

DOE Patents (OSTI)

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.

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

1999-01-01T23:59:59.000Z

204

Electronic states in epitaxial graphene fabricated on silicon carbide  

SciTech Connect

An analytical expression for the density of states of a graphene monolayer interacting with a silicon carbide surface (epitaxial graphene) is derived. The density of states of silicon carbide is described within the Haldane-Anderson model. It is shown that the graphene-substrate interaction results in a narrow gap of {approx}0.01-0.06 eV in the density of states of graphene. The graphene atom charge is estimated; it is shown that the charge transfer from the substrate is {approx}10{sup -3}-10{sup -2}e per graphene atom.

Davydov, S. Yu., E-mail: Sergei_Davydov@mail.ru [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)

2011-08-15T23:59:59.000Z

205

Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride  

DOE Patents (OSTI)

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.

Koc, R.; Glatzmaier, G.C.

1995-05-23T23:59:59.000Z

206

Process for forming silicon carbide films and microcomponents  

DOE Patents (OSTI)

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.

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

1999-01-19T23:59:59.000Z

207

Method for forming fibrous silicon carbide insulating material  

DOE Patents (OSTI)

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.

Wei, George C. (Oak Ridge, TN)

1984-01-01T23:59:59.000Z

208

Method for forming fibrous silicon carbide insulating material  

DOE Patents (OSTI)

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.

Wei, G.C.

1983-10-12T23:59:59.000Z

209

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

DOE Patents (OSTI)

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.

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

1985-05-06T23:59:59.000Z

210

ATP hydrolysis stimulates large length fluctuations in single actin filaments  

E-Print Network (OSTI)

Polymerization dynamics of single actin filaments is investigated theoretically using a stochastic model that takes into account the hydrolysis of ATP-actin subunits, the geometry of actin filament tips, the lateral interactions between the monomers as well as the processes at both ends of the polymer. Exact analytical expressions are obtained for a mean growth velocity and for dispersion in length fluctuations. It is found that the ATP hydrolysis has a strong effect on dynamic properties of single actin filaments. At high concentrations of free actin monomers the mean size of unhydrolyzed ATP-cap is very large, and the dynamics is governed by association/dissociation of ATP-actin subunits. However, at low concentrations the size of the cap becomes finite, and the dissociation of ADP-actin subunits makes a significant contribution to overall dynamics. Actin filament length fluctuations reach the maximum at the boundary between two dynamic regimes, and this boundary is always larger than the critical concentration. Random and vectorial mechanisms of hydrolysis are compared, and it is found that they predict qualitatively similar dynamic properties. The possibility of attachment and detachment of oligomers is also discussed. Our theoretical approach is successfully applied to analyze the latest experiments on the growth and length fluctuations of individual actin filaments.

Evgeny B. Stukalin; Anatoly B. Kolomeisky

2005-07-27T23:59:59.000Z

211

Solid-State Formation of Titanium Carbide and Molybdenum Carbide as Contcts for Carbon-Containing Semiconductors  

SciTech Connect

Metal carbides are good candidates to contact carbon-based semiconductors (SiC, diamond, and carbon nanotubes). Here, we report on an in situ study of carbide formation during the solid-state reaction between thin Ti or Mo films and C substrates. Titanium carbide (TiC) was previously reported as a contact material to diamond and carbon nanotubes. However, the present study shows two disadvantages for the solid-state reaction of Ti and C. First, because Ti reacts readily with oxygen, a capping layer should be included to enable carbide formation. Second, the TiC phase can exist over a wide range of composition (about 10%, i.e., from Ti{sub 0.5}C{sub 0.5} to Ti{sub 0.6}C{sub 0.4}), leading to significant variations in the properties of the material formed. The study of the Mo-C system suggests that molybdenum carbide (Mo{sub 2}C) is a promising alternative, since the phase shows a lower resistivity (about 45% lower than for TiC), the carbide forms below 900 {sup o}C, and its formation is less sensitive to oxidation as compared with the Ti-C system. The measured resistivity for Mo{sub 2}C is p=59 {mu}{Omega} cm, and from kinetic studies an activation energy for Mo{sub 2}C formation of E{sub a}=3.15+/-0.15 eV was obtained.

Leroy,W.; Detavernier, C.; van Meirhaeghe, R.; Kellock, A.; Lavoie, C.

2006-01-01T23:59:59.000Z

212

Method for homogenizing alloys susceptible to the formation of carbide stringers and alloys prepared thereby  

DOE Patents (OSTI)

A novel fabrication procedure prevents or eliminates the reprecipitation of segregated metal carbides such as stringers in Ti-modified Hastelloy N and stainless steels to provide a novel alloy having carbides uniformly dispersed throughout the matrix. The fabrication procedure is applicable to other alloys prone to the formation of carbide stringers. The process comprises first annealing the alloy at a temperature above the single phase temperature for sufficient time to completely dissolve carbides and then annealing the single phase alloy for an additional time to prevent the formation of carbide stringers upon subsequent aging or thermomechanical treatment.

Braski, David N. (Oak Ridge, TN); Leitnaker, James M. (Kingston, TN)

1980-01-01T23:59:59.000Z

213

Temperature dependency of MOSFET device characteristics in 4H-and 6H-silicon carbide (SiC)  

E-Print Network (OSTI)

Temperature dependency of MOSFET device characteristics in 4H- and 6H-silicon carbide (SiC) Md was arranged by Prof. A. Iliadis Abstract The advantages of silicon carbide (SiC) over silicon are significant; Silicon carbide; Temperature variation effect 1. Introduction Silicon carbide, a wide bandgap material

Tolbert, Leon M.

214

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

E-Print Network (OSTI)

carbide coatings using an axially fed DC-plasmatron S. Sharafata,U , A. Kobayashib , S. Chena , N 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

Ghoniem, Nasr M.

215

Effect of filament supports on emissive probe measurements  

SciTech Connect

We have constructed an emissive probe with a thin tungsten filament spot-welded across two nickel wires insulated with ceramic paint. We show that the ceramic supports covering the nickel wires have a large effect on the potential measurements in low-density plasmas. It is found that the potential measured by the emissive probe is more negative than the potential derived from a Langmuir probe current-voltage (I-V) characteristic curve when the plasma density is so low that the emitting filament remains immersed in the sheaths of the ceramic supports. The length of the filament L needs to be larger than about 2 Debye lengths (L > 2{lambda}{sub De}) in order to avoid the influence of the ceramic supports and to achieve reliable plasma potential measurements using emissive probes.

Wang, X.; Howes, C. T. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80309 (United States); NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309 (United States); Horanyi, M. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80309 (United States); NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Robertson, S. [NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States)

2013-01-15T23:59:59.000Z

216

Nuclear breeder reactor fuel element with silicon carbide getter  

DOE Patents (OSTI)

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.

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

1987-01-01T23:59:59.000Z

217

Epitaxial graphene on silicon carbide: Introduction to structured graphene  

E-Print Network (OSTI)

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

Paris-Sud XI, Université de

218

Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applicaitons  

SciTech Connect

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.

Z. Zak Fang, H. Y. Sohn

2009-03-10T23:59:59.000Z

219

Tungsten-yttria carbide coating for conveying copper  

DOE Patents (OSTI)

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.

Rothman, Albert J. (Livermore, CA)

1993-01-01T23:59:59.000Z

220

Surface Coating of Tungsten Carbide by Electric Exploding of Contact  

SciTech Connect

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.

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

2011-01-17T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Characterization of terahertz emission from a dc-biased filament in air  

SciTech Connect

We demonstrate that the terahertz emission from a dc-biased filament can be regarded as a sum of an elliptically polarized terahertz source (generated by a filament without external electric field) and a linearly polarized terahertz source induced by the external electric field applied to the filament. The peak frequency and linewidth of the linearly polarized terahertz source are related to the average plasma density of the filament.

Chen Yanping; Wang Tiejun; Marceau, Claude; Chin, See Leang [Centre d'Optique, Photonique et Laser (COPL), and Departement de Physique, de genie physique et d'optique, Universite Laval, Quebec, Quebec G1V 0A6 (Canada); Theberge, Francis; Chateauneuf, Marc; Dubois, Jacques [Defence Research and Development Canada-Valcartier, 2459 Pie-XI Blvd. North, Quebec, Quebec G3J 1X5 (Canada); Kosareva, Olga [International Laser Center, Physics Department, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation)

2009-09-07T23:59:59.000Z

222

Detection of an optical filament in the Monogem Ring  

E-Print Network (OSTI)

The Monogem Ring is a huge bright soft X-ray enhancement with a diameter of ~ 25$\\degr$. This 0.3 kpc distant structure is a peculiar Galactic supernova remnant in that it is obviously visible only in X-rays, due to its expansion into a region of extremely low ambient density: hence, practically no optical emission or a neutral HI shell was expected to be detectable. - Here we report on the discovery of a very faint arc-like nebula on a POSS II R film copy, at the south-eastern borders of the MR. Spectroscopy revealed this filament to have a very large [SII]$\\lambda$ 6716+6731/Halpha ratio of up to ~ 1.8, indicating shock excitation, and a low density of N_e thin (~ 1 arcmin), structured filament, stretching N-S. We believe that this filament belongs to the MR and became visible due to the interaction of the expanding remnant with a mild density increase in the interstellar medium. Only one other possible optical filament of the MR has been reported in the literature, but no spectrum was provided.

R. Weinberger; S. Temporin; B. Stecklum

2005-11-18T23:59:59.000Z

223

The role of filament activation in a solar eruption  

E-Print Network (OSTI)

Observations show that the mutual relationship between filament eruptions and solar flares cannot be described in terms of an unique scenario. In some cases, the eruption of a filament appears to trigger a flare, while in others the observations are more consistent with magnetic reconnection that produces both the flare observational signatures (e.g., ribbons, plasma jets, post-flare loops, etc.) and later the destabilization and eruption of a filament. We study an event which occurred in NOAA 8471, where a flare and the activation of (at least) two filaments were observed on 28 February 1999. By using imaging data acquired in the 1216, 1600, 171 and 195 \\AA\\ TRACE channels and by BBSO in the continnum and in H$\\alpha$, a morphological study of the event is carried out. Using TRACE 1216 and 1600 \\AA\\ data, an estimate of the "pure" Ly$\\alpha$ power is obtained. The extrapolation of the magnetic field lines is done using the SOHO/MDI magnetograms and assuming a potential field. The potential magnetic field ext...

da Costa, Fatima Rubio; Fletcher, Lyndsay; Romano, Paolo; Labrosse, Nicolas

2014-01-01T23:59:59.000Z

224

Detection of a redshift 3.04 filament  

E-Print Network (OSTI)

The filamentary structure of the early universe has until now only been seen in numerical simulations. Despite this lack of direct observational evidence, the prediction of early filamentary structure formation in a Cold Dark Matter dominated universe has become a paradigm for our understanding of galaxy assembly at high redshifts. Clearly observational confirmation is required. Lyman Break galaxies are too rare to be used as tracers of filaments and we argue that to map out filaments in the high z universe, one will need to identify classes of objects fainter than those currently accessible via the Lyman Break technique. Objects selected via their Ly-alpha emission, and/or as DLA absorbers, populate the faintest accessible part of the high redshift galaxy luminosity function, and as such make up good candidates for objects which will map out high redshift filaments. Here we present the first direct detection of a filament (at z=3.04) mapped by those classes of objects. The observations are the deepest yet to have been done in Ly-alpha imaging at high redshift, and they reveal a single string of proto-galaxies spanning about 5 Mpc (20 Mpc comoving). Expanding the cosmological test proposed by Alcock & Paczynski (1979), we outline how observations of this type can be used to determine Omega_Lambda at z=3.

P. Moller; J. U. Fynbo

2001-05-07T23:59:59.000Z

225

INTRODUCTION Neural intermediate filaments (NIF) containing one or more of  

E-Print Network (OSTI)

INTRODUCTION Neural intermediate filaments (NIF) containing one or more of five different types, NIF possess common structural features, including a conserved alpha-helical central rod domain of NIF in the presence of NF-L (Zackroff et al., 1982; Hisanaga and Hirokawa, 1988; Balin and Lee, 1991

Goldman, Robert D.

226

Evolution of Genes and Gene Networks in Filamentous Fungi  

E-Print Network (OSTI)

......................................................................................................................... 137 ix LIST OF FIGURES FIGURE Page 1 Phylogenetic tree assembled from fungi with sequenced genomes ........... 5 2... (subsistence on detritus) lifestyle, may explain such rapid amino acid divergence. Figs. 1 and 2 are phylogenetic trees for the filamentous fungi. Fig. 2 shows the 10 major classes of the 5 Fig. 1: Phylogenetic tree assembled from fungi with sequenced...

Greenwald, Charles Joaquin

2011-10-21T23:59:59.000Z

227

Quantitative Characterization of Filament Dynamics by Single-Molecule Lifetime  

E-Print Network (OSTI)

CHAPTER 29 Quantitative Characterization of Filament Dynamics by Single-Molecule Lifetime. Single-Molecule Lifetime Measurements A. Extract and Sample Preparation B. Microscopy C. Data Analysis Dynamics C. Connecting to Other Types of Measurements IV. Results and Conclusion References Abstract Single-molecule

Needleman, Daniel

228

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

SciTech Connect

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.

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

2014-09-01T23:59:59.000Z

229

SILICON CARBIDE CERAMICS FOR COMPACT HEAT EXCHANGERS  

SciTech Connect

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

DR. DENNIS NAGLE; DR. DAJIE ZHANG

2009-03-26T23:59:59.000Z

230

Diamond-Silicon Carbide Composite And Method For Preparation Thereof  

DOE Patents (OSTI)

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.

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

2005-09-06T23:59:59.000Z

231

Protective coating for alumina-silicon carbide whisker composites  

DOE Patents (OSTI)

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.

Tiegs, Terry N. (Lenoir City, TN)

1989-01-01T23:59:59.000Z

232

Preparation of silicon carbide film by a plasma focus device  

Science Journals Connector (OSTI)

Silicon carbide (SiC) films were grown on the silicon (100) substrate by a 20 kJ Mather-type dense plasma focus device. The preparation method and characterization data are presented. X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM) and nano-indentor were employed for the characterization of the samples obtained at different axial position of 50 mm, 90 mm, 130 mm and 170 mm, respectively. Polycrystalline 3CSiC were obtained at the position of 90 mm and 130 mm from XRD and FTIR spectra. SEM image showed that the silicon carbide films obtained at the position of 90 mm are porous on surface layer. Nano-indentor indicates that the film obtained at the position of 130 mm has the highest mechanical hardness.

Z.P. Wang; H.R. Yousefi; Y. Nishino; H. Ito; K. Masugata

2008-01-01T23:59:59.000Z

233

In situ transmission electron microscopy analysis of conductive filament during solid electrolyte resistance switching  

SciTech Connect

An in situ transmission electron microscopy (TEM) analysis of a solid electrolyte, Cu-GeS, during resistance switching is reported. Real-time observations of the filament formation and disappearance process were performed in the TEM instrument and the conductive-filament-formation model was confirmed experimentally. Narrow conductive filaments were formed corresponding to resistance switching from high- to low-resistance states. When the resistance changed to high-resistance state, the filament disappeared. It was also confirmed by use of selected area diffractometry and energy-dispersive x-ray spectroscopy that the conductive filament was made of nanocrystals composed mainly of Cu.

Fujii, Takashi; Arita, Masashi; Takahashi, Yasuo [Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814 (Japan); Fujiwara, Ichiro [Semiconductor Technology Academic Research Center, 3-17-2 Shinyokohama, Kohoku-ku, Yokohama 222-0033 (Japan)

2011-05-23T23:59:59.000Z

234

Photonic Crystal Cavities in Cubic Polytype Silicon Carbide Films  

E-Print Network (OSTI)

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 1250 - 1600 nm. Finally, we discuss possible applications in nonlinear optics, optical interconnects, and quantum information science.

Radulaski, Marina; Buckley, Sonia; Rundquist, Armand; Provine, J; Alassaad, Kassem; Ferro, Gabriel; Vu?kovi?, Jelena

2013-01-01T23:59:59.000Z

235

Process for growing silicon carbide whiskers by undercooling  

DOE Patents (OSTI)

A method of growing silicon carbide whiskers, especially in the .beta. form, using a heating schedule wherein the temperature of the atmosphere in the growth zone of a furnace is first heated to or beyond the growth temperature and then is cooled to or below the growth temperature to induce nucleation of whiskers at catalyst sites at a desired point in time which results in the selection.

Shalek, Peter D. (Los Alamos, NM)

1987-01-01T23:59:59.000Z

236

Carbide precipitation in gamma-TiAl alloys  

SciTech Connect

Carbide precipitation in gamma-TiAl is observed and found to involve the formation of coherent, rod-shaped perovskite precipitates as a metastable transition phase. At temperatures above 750 deg C, the formation of plate-shaped H-phase particles on dislocations and grain boundaries is accompanied by dissolution of the perovskite precipitate dispersions. This temperature regime includes possible service temperatures for gamma-TiAl-based alloys. 10 refs.

Chen, S.; Beaven, P.A.; Wagner, R. (GKSS-Forschungszentrum Geesthacht GmbH, (Germany))

1992-04-01T23:59:59.000Z

237

Ceramic composites reinforced with modified silicon carbide whiskers  

DOE Patents (OSTI)

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.

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

1990-01-01T23:59:59.000Z

238

15 - Processing of Refractory Carbides and Nitrides (Coatings)  

Science Journals Connector (OSTI)

Publisher Summary This chapter reviews the coating processes of refractory carbides and nitrides. Coatings of refractory carbides and nitrides have great industrial importance with a wide range of applications in semiconductors and other electronic components, in cutting tools, gas-turbine vanes and blades, precision bearings, punch sets, extruders, prostheses, and many other products. The surface of a material may be exposed to wear, corrosion, radiation, electrical or magnetic fields, and other phenomena and hence, it must have the ability to withstand these environments. This can be accomplished by coating the base material to obtain a composite in which the surface properties may be considerably different from those of the substrate. Chemical vapor deposition (CVD) and physical vapor deposition (PVD) belong to the class of vapor-transfer processes, which are atomistic in naturethat is, the deposition species are atoms or molecules or a combination of these. The coatings are also commonly known as thin-films when their thickness is less than 10 ?m. CVD is a versatile process that is well adapted to the production of all the refractory carbides and nitrides, not only as coatings but also as powders, bulk/monolithic components, and fibers. It may be defined as the deposition of a solid on a heated surface from a chemical reaction in the vapor phase.

Hugh O. Pierson

1996-01-01T23:59:59.000Z

239

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

SciTech Connect

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.

Vojvodic, Aleksandra

2012-05-11T23:59:59.000Z

240

High-Resolution Soft X-Ray Spectral Analysis in the CK Region of Titanium Carbide (TiC) using the DV-X alpha Molecular Orbital Method  

E-Print Network (OSTI)

of rock-salt structured metal carbides. K. Shimomura et al.in metals, such as metal carbides and carbon/metal alloys,the CK region of metal carbides, and analyzed the spectral

Shimomura, Kenta

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

High-Resolution Soft X-Ray Spectral Analysis in the CK Region of Titanium Carbide (TiC) using the DV-X alpha Molecular Orbital Method  

E-Print Network (OSTI)

in the CK Region of Titanium Carbide (TiC) using the DV-X?USA Keyword titanium carbide, soft X-ray spectroscopy,C K region of titanium carbide (TiC). The spectral profiles

Shimomura, Kenta

2010-01-01T23:59:59.000Z

242

ARC DISCHARGE SYNTHESIS AND MORPHOLOGY CONTROL OF EARLY TRANSITION METAL CARBIDE NANOPATICLES.  

E-Print Network (OSTI)

??This work is directed to the understanding of the synthesis and morphology control of early transition metal carbides. Chapter 1 gives an introduction to fcc (more)

Grove , David

2010-01-01T23:59:59.000Z

243

Electronic properties and reliability of the silicon dioxide / silicon carbide interface.  

E-Print Network (OSTI)

??Silicon carbide has been preferred over other wide band-gap semiconductors for high power applications because of its unique ability to grow a thermal oxide, challenges (more)

Rozen, John

2008-01-01T23:59:59.000Z

244

LASER METALLIZATION AND DOPING FOR SILICON CARBIDE DIODE FABRICATION AND ENDOTAXY.  

E-Print Network (OSTI)

??Silicon carbide is a promising semiconductor material for high voltage, high frequency and high temperature devices due to its wide bandgap, high breakdown electric field (more)

Tian, Zhaoxu

2006-01-01T23:59:59.000Z

245

Tunable carbon nanotube-tungsten carbide nanoparticles heterostructures by vapor deposition  

SciTech Connect

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.

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

246

E-Print Network 3.0 - amorphous silicon carbide Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

50, mai 1989 Summary: revetementdans le substrat. Abstract - Cuttingtools made of A1203+TiC, silicon nitride,carbide, and stabi- lized... with Tic, silicon nitride,...

247

Synthesis of uranium nitride and uranium carbide powder by carbothermic reduction  

SciTech Connect

Uranium nitride and uranium carbide are being considered as high burnup fuels in next generation nuclear reactors and accelerated driven systems for the transmutation of nuclear waste. The same characteristics that make nitrides and carbides candidates for these applications (i.e. favorable thermal properties, mutual solubility of nitrides, etc.), also make these compositions candidate fuels for space nuclear reactors. In this paper, we discuss the synthesis and characterization of depleted uranium nitride and carbide for a space nuclear reactor program. Importantly, this project emphasized that to synthesize high quality uranium nitride and carbide, it is necessary to understand the exact stoichiometry of the oxide feedstock. (authors)

Dunwoody, J.T.; Stanek, C.R.; McClellan, K.J.; Voit, S.L.; Volz, H.M. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Hickman, R.R. [NASA Marshall Space Flight Center, Huntsville, Alabama (United States)

2007-07-01T23:59:59.000Z

248

E-Print Network 3.0 - alternative lmfbr carbide Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

illustrating the rich behavior of carbo-nitride materials. The early transition metal carbides and nitrides... the calculations re- ported here were performed with the...

249

STUDYING INTERCLUSTER GALAXY FILAMENTS THROUGH STACKING gmBCG GALAXY CLUSTER PAIRS  

SciTech Connect

We present a method to study the photometric properties of galaxies in filaments by stacking the galaxy populations between pairs of galaxy clusters. Using Sloan Digital Sky Survey data, this method can detect the intercluster filament galaxy overdensity with a significance of {approx}5{sigma} out to z = 0.40. Using this approach, we study the g - r color and luminosity distribution of filament galaxies as a function of redshift. Consistent with expectation, filament galaxies are bimodal in their color distribution and contain a larger blue galaxy population than clusters. Filament galaxies are also generally fainter than cluster galaxies. More interestingly, the observed filament population seems to show redshift evolution at 0.12 < z < 0.40: the blue galaxy fraction has a trend to increase at higher redshift; such evolution is parallel to the ''Butcher-Oemler effect'' of galaxy clusters. We test the dependence of the observed filament density on the richness of the cluster pair: richer clusters are connected by higher density filaments. We also test the spatial dependence of filament galaxy overdensity: this quantity decreases when moving away from the intercluster axis between a cluster pair. This method provides an economical way to probe the photometric properties of filament galaxies and should prove useful for upcoming projects like the Dark Energy Survey.

Zhang Yuanyuan; Dietrich, Joerg P.; McKay, Timothy A.; Nguyen, Alex T. Q. [Department of Physics, University of Michigan, Ann Arbor, MI (United States); Sheldon, Erin S. [Brookhaven National Laboratory, Upton, NY (United States)

2013-08-20T23:59:59.000Z

250

Submitted to ApJ Letters, June 29, 2005 Are Presolar Silicon Carbide Grains from Novae Actually from Supernovae?  

E-Print Network (OSTI)

Submitted to ApJ Letters, June 29, 2005 Are Presolar Silicon Carbide Grains from Novae Actually stellar nucleosynthesis and mixing. The best-studied presolar phase, silicon carbide (SiC), exhibits

Nittler, Larry R.

251

PII S0016-7037(01)00802-X Volatilization kinetics of silicon carbide in reducing gases: An experimental study with  

E-Print Network (OSTI)

PII S0016-7037(01)00802-X Volatilization kinetics of silicon carbide in reducing gases occurring hexagonal sili- con carbide ( -SiC), and -SiC, the cubic form, are occasion- ally reported

Grossman, Lawrence

252

General Multiobjective Force Field Optimization Framework, with Application to Reactive Force Fields for Silicon Carbide  

E-Print Network (OSTI)

Fields for Silicon Carbide Andres Jaramillo-Botero,* Saber Naserifar, and William A. Goddard, III: (1) the ReaxFF reactive force field for modeling the adiabatic reactive dynamics of silicon carbide specific force field parameters for tripod metal templates, tripodMO(CO)3, using the root mean square

Goddard III, William A.

253

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

SciTech Connect

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.

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

2014-05-27T23:59:59.000Z

254

Four-point probe characterization of 4H silicon carbide N. Chandra a,  

E-Print Network (OSTI)

Four-point probe characterization of 4H silicon carbide N. Chandra a, , V. Sharma a , G.Y. Chung b carbide Four-point probe Thermionic-field emission Contact resistance a b s t r a c t We report on four

Schroder, Dieter K.

255

Electronic structure and pairwise interactions in substoichiometric transition metal carbides and nitrides  

E-Print Network (OSTI)

1001 Electronic structure and pairwise interactions in substoichiometric transition metal carbides observations expéri- mentales. Abstract 2014 In substoichiometric transition metal carbides and nitrides This paper is devoted to the study of the ordering processes in substoichiometric transition metal carbi- des

Paris-Sud XI, Université de

256

carbides. The multiphase/polytypic region can be expected to occur also in the nitrides because  

E-Print Network (OSTI)

in valence electron concentration where sev- eral phases of the 3d, 4d, and 5d transition metal carbides have, Transition Metal Carbides and Nitrides (Academic Press, New York, 1971). 6. C. Maerky, M.-O. Guillou, J. L is predicted to be substantially enhanced over that of traditional transition metal car- bide/nitride coatings

Shen, Guoyin

257

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

E-Print Network (OSTI)

a possibility of replacing precious metal anode catalysts with transition metal compounds for hydrogen oxidation density of states of tungsten carbides resembles that of noble metal platinum.4,5 FundamentalNanostructured tungsten carbide catalysts for polymer electrolyte fuel cells X. G. Yanga and C. Y

258

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

E-Print Network (OSTI)

transition metals, rare earths and actinides react with carbon and nitrogen to form metallic carbides experimental evidence for short and long-range ordering of point defects in metallic transition metal, rareCOMPOUNDS. ORDER AND DISORDER IN CARBIDES AND NITRIDES Ch. H. DE NOVION and V. MAURICE SESI, C

Paris-Sud XI, Université de

259

Irradiation and annealing of p-type silicon carbide  

SciTech Connect

The development of the technology of semiconductor devices based on silicon carbide and the beginning of their industrial manufacture have made increasingly topical studies of the radiation hardness of this material on the one hand and of the proton irradiation to form high-receptivity regions on the other hand. This paper reports on a study of the carrier removal rate (V{sub d}) in p-6H-SiC under irradiation with 8 MeV protons and of the conductivity restoration in radiation- compensated epitaxial layers of various p-type silicon carbide polytypes. V{sub d} was determined by analysis of capacitance-voltage characteristics and from results of Hall effect measurements. It was found that the complete compensation of samples with the initial value of Na - Nd ? 1.5 10{sup 18} cm{sup ?3} occurs at an irradiation dose of ?1.1 10{sup 16} cm{sup ?2}. It is shown that specific features of the sublimation layer SiC (compared to CVD layers) are clearly manifested upon the gamma and electron irradiation and are hardly noticeable under the proton and neutron irradiation. It was also found that the radiation-induced compensation of SiC is retained after its annealing at ?1000C. The conductivity is almost completely restored at T ? 1200C. This character of annealing of the radiation compensation is independent of a silicon carbide polytype and the starting doping level of the epitaxial layer. The complete annealing temperatures considerably exceed the working temperatures of SiC-based devices. It is shown that the radiation compensation is a promising method in the technology of high-temperature devices based on SiC.

Lebedev, Alexander A.; Bogdanova, Elena V.; Grigor'eva, Maria V.; Lebedev, Sergey P. [A.F. Ioffe Physical-Technical Institute, St. Petersburg, 194021 (Russian Federation); Kozlovski, Vitaly V. [St. Petersburg State Polytechnic University, St. Petersburg, 195251 (Russian Federation)

2014-02-21T23:59:59.000Z

260

PROPERTIES OF DEFECTS AND IMPLANTS IN Mg+ IMPLANTED SILICON CARBIDE  

SciTech Connect

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.

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

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Method of fabricating silicon carbide coatings on graphite surfaces  

DOE Patents (OSTI)

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.

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

1994-07-26T23:59:59.000Z

262

Method of fabricating silicon carbide coatings on graphite surfaces  

DOE Patents (OSTI)

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.

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

1994-01-01T23:59:59.000Z

263

Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature  

E-Print Network (OSTI)

Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature Simone film crystal growth of silicon carbide (SiC), a semiconductor syn- thesized to replace silicon in harsh

Alfè, Dario

264

Brittle dynamic fracture of crystalline cubic silicon carbide ,,3C-SiC... via molecular dynamics simulation  

E-Print Network (OSTI)

Brittle dynamic fracture of crystalline cubic silicon carbide ,,3C-SiC... via molecular dynamics for three low-index crack surfaces, i.e., 110 , 111 , and 100 , in crystalline cubic silicon carbide 3C Institute of Physics. DOI: 10.1063/1.2135896 I. INTRODUCTION Potential applications of silicon carbide Si

Southern California, University of

265

CHIN.PHYS.LETT. Vol. 25, No. 9 (2008) 3463 Probing Field Emission from Boron Carbide Nanowires  

E-Print Network (OSTI)

CHIN.PHYS.LETT. Vol. 25, No. 9 (2008) 3463 Probing Field Emission from Boron Carbide Nanowires, Sun Yat-sen University, Guangzhou 510275 (Received 10 March 2008) High density boron carbide nanowires together suggest that boron carbide nanowires are promising candidates for electron emission nanodevices

Gao, Hongjun

266

A Comparison of Mechanical Properties of Three MEMS Materials -Silicon Carbide, Ultrananocrystalline Diamond, and Hydrogen-Free Tetrahedral  

E-Print Network (OSTI)

A Comparison of Mechanical Properties of Three MEMS Materials - Silicon Carbide investigated the mechanical properties of three new materials for MEMS/NEMS devices: silicon carbide (SiC) from mechanical, electrical, and tribological properties such as silicon carbide (SiC), ultrananocrystalline

Espinosa, Horacio D.

267

Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline  

E-Print Network (OSTI)

Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline and amorphous silicon carbide Priya Vashishta,a Rajiv K. Kalia Silicon carbide SiC has been proposed for a wide range of technological applications

Southern California, University of

268

Chem.Mater. 1996,7, 1419-1421 1419 Encapsulation of Iron Carbide in Carbon Nanocapsules  

E-Print Network (OSTI)

Chem.Mater. 1996,7, 1419-1421 1419 Encapsulation of Iron Carbide in Carbon Nanocapsules Nikolai S Manuscript Received April 24, 1995@ Whiskers of iron carbide encased in carbon shells have been prepared from microscopy. The iron carbide whiskers range in length from 300 to 500 nm, and their widths are approximately

Wang, Zhong L.

269

Accepted to Diamond and Related Materials A kinetic model of diamond nucleation and silicon carbide interlayer formation during  

E-Print Network (OSTI)

Accepted to Diamond and Related Materials A kinetic model of diamond nucleation and silicon carbide Engineering, Colorado State University, Fort Collins, CO, USA Abstract The presence of thin silicon carbide diffusion of carbon atoms into the silicon carbide layer, and the morphology and orientation of the diamond

Dandy, David

270

Materials Science and Engineering A245 (1998) 293299 The wettability of silicon carbide by AuSi alloys  

E-Print Network (OSTI)

Materials Science and Engineering A245 (1998) 293­299 The wettability of silicon carbide by Au. Keywords: Wettability; Contact angle; Liquid metals; Silicon carbide 1. Introduction The interface properties of silicon carbide­liquid metals (wetting, adhesion, contact interaction) are im- portant

Grigoriev, Alexei

271

By Earle B. Amey Tungsten's unique high-temperature in Metal Bulletin (London). ferrotungsten, carbide powder blends, and  

E-Print Network (OSTI)

). ferrotungsten, carbide powder blends, and properties can be utilized advantageously in the As a result properties of its carbide continue to scrap, and sodium tungstate and away from the provide important items increased in all imported tungsten materials. the cemented carbide end-use sectors that A summary

272

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

E-Print Network (OSTI)

of Silicon Carbide Power Electronics for Modern Wind Turbine Full Scale Frequency Converter Hui Zhang, Member and fast switching speeds, silicon carbide (SiC) power electronics are considered for use in power), silicon carbide (SiC), wind generation. I. INTRODUCTION VARIABLE speed capability allows a wind turbine

Tolbert, Leon M.

273

Improvement of pin-type amorphous silicon solar cell performance by employing double silicon-carbide p-layer structure  

E-Print Network (OSTI)

Improvement of pin-type amorphous silicon solar cell performance by employing double silicon-carbide Received 30 October 2003; accepted 18 November 2003 We investigated a double silicon-carbide p-layer structure consisting of a undiluted p-type amorphous silicon-carbide (p-a-SiC:H) window layer and a hydrogen

Kim, Yong Jung

274

Midinfrared Index Sensing of pL-Scale Analytes Based on Surface Phonon Polaritons in Silicon Carbide  

E-Print Network (OSTI)

Carbide Burton Neuner III, Dmitriy Korobkin, Chris Fietz, Davy Carole,§ Gabriel Ferro,§ and Gennady Shvets at the silicon carbide/analyte interface in the Otto configuration. Attenuated total reflectance measurements carbide gratings.3 Resonant techniques are often needed for sensing because, e.g., weak vibrational modes

Texas at Austin, University of

275

Bond-order potential for transition metal carbide cluster for the growth simulation of a single-walled carbon nanotube  

E-Print Network (OSTI)

Bond-order potential for transition metal carbide cluster for the growth simulation of a single for transition metal carbide cluster is developed in the form of the bond-order type potential function-order potential; Carbon nanotube; transition metal carbide cluster *Corresponding Author. Fax: +81-3-5841-8653 E

Maruyama, Shigeo

276

Characterization of new Co and Ru on -WC catalysts for Fischer-Tropsch reaction. Influence of the carbide surface state.  

E-Print Network (OSTI)

[8]. Among the group VI transition metal carbides, the hexagonal tungsten carbide WC is a remarkable proceeds on supported transition metal catalysts, Co or Fe on oxide supports generally Al2O3 or SiO2 [1 of the carbide surface state. A. Griboval-Constant(1) *, J.-M. Giraudon(1) , I. Twagishema(1) , G. Leclercq(1

Paris-Sud XI, Université de

277

First-Principles Study of MetalCarbide/Nitride Adhesion: Al/VC vs. Al/VN Donald J. Siegel  

E-Print Network (OSTI)

-oxide ce- ramics. Within this class, the transition metal carbides and ni- trides are a particularly knowledge, there have been only three studies of adhesion between metals and transition metal carbidesFirst-Principles Study of Metal­Carbide/Nitride Adhesion: Al/VC vs. Al/VN Donald J. Siegel

Adams, James B

278

Characterization of new Co and Ru on -WC catalysts for Fischer-Tropsch reaction. Influence of the carbide surface state.  

E-Print Network (OSTI)

of the metallic particles [8]. Among the group VI transition metal carbides, the hexagonal tungsten carbide WC monoxide and hydrogen. FT synthesis proceeds on supported transition metal catalysts, Co or Fe on oxide of the carbide surface state. A. Griboval-Constant(1) *, J.-M. Giraudon(1) , I. Twagishema(1) , G. Leclercq(1

Paris-Sud XI, Université de

279

Field effect in epitaxial graphene on a silicon carbide substrate Sarnoff Corporation, CN5300, Princeton, New Jersey 08543  

E-Print Network (OSTI)

deposition on the surfaces of transition metal or transition metal carbide single crystals, and the physical on a graphitized SiC surface, as opposed to highly conductive metal and metal carbide substrates that require1 Field effect in epitaxial graphene on a silicon carbide substrate Gong Gua) Sarnoff Corporation

Feenstra, Randall

280

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Award-Winning Silicon Carbide Power Electronics Award-Winning Silicon Carbide Power Electronics (October 2012) Fact Sheet: Award-Winning Silicon Carbide Power Electronics (October 2012) Operating at high temperatures and with reduced energy losses, two silicon carbide power electronics (PE) projects were awarded the prestigious R&D 100 Award. This technology was funded as a Small Business Innovation Research project as part of DOE's Energy Storage Program effort to develop and commercialize a new generation of PE systems. PE systems are a critical part of all energy storage systems, interfacing the energy storage device and the load (the end user) and often accounting for greater than 25% of the overall storage system cost. Fact Sheet: Award-Winning Silicon Carbide Power Electronics (October 2012)

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Influence of interlayer trapping and detrapping mechanisms on the electrical characterization of hafnium oxide/silicon nitride stacks on silicon  

SciTech Connect

Al/HfO{sub 2}/SiN{sub x}:H/n-Si metal-insulator-semiconductor capacitors have been studied by electrical characterization. Films of silicon nitride were directly grown on n-type silicon substrates by electron cyclotron resonance assisted chemical vapor deposition. Silicon nitride thickness was varied from 3 to 6.6 nm. Afterwards, 12 nm thick hafnium oxide films were deposited by the high-pressure sputtering approach. Interface quality was determined by using current-voltage, capacitance-voltage, deep-level transient spectroscopy (DLTS), conductance transients, and flatband voltage transient techniques. Leakage currents followed the Poole-Frenkel emission model in all cases. According to the simultaneous measurement of the high and low frequency capacitance voltage curves, the interface trap density obtained for all the samples is in the 10{sup 11} cm{sup -2} eV{sup -1} range. However, a significant increase in this density of about two orders of magnitude was obtained by DLTS for the thinnest silicon nitride interfacial layers. In this work we probe that this increase is an artifact that must be attributed to traps existing at the HfO{sub 2}/SiN{sub x}:H intralayer interface. These traps are more easily charged or discharged as this interface comes near to the substrate, that is, as thinner the SiN{sub x}:H interface layer is. The trapping/detrapping mechanism increases the capacitance transient and, in consequence, the DLTS measurements have contributions not only from the insulator/substrate interface but also from the HfO{sub 2}/SiN{sub x}:H intralayer interface.

Garcia, H.; Duenas, S.; Castan, H.; Gomez, A.; Bailon, L. [Departamento de Electricidad y Electronica, E.T.S.I. Telecomunicacion, Universidad de Valladolid, Campus 'Miguel Delibes', 47011 Valladolid (Spain); Toledano-Luque, M.; Prado, A. del; Martil, I.; Gonzalez-Diaz, G. [Departamento de Fisica Aplicada III (Electricidad y Electronica), Facultad de Ciencias Fisicas, Universidad Complutense, 28040 Madrid (Spain)

2008-11-01T23:59:59.000Z

282

Submicron carbon filament cement-matrix composites for electromagnetic interference shielding  

SciTech Connect

Carbon filaments of diameter 0.1 mm were found to be a much more effective additive than conventional carbon fibers of diameter 10 mm in providing cement pastes capable of electromagnetic interference shielding. With 0.54 vol. % filaments and a shield thickness of 4 mm, a shielding effectiveness of 30 dB was attained at 1--2 GHz. However, the filaments were less effective than the fibers for reinforcing and for providing strain sensing cement-matrix composites.

Fu, X.; Chung, D.D.L. [State Univ. of New York, Buffalo, NY (United States). Composite Materials Research Lab.] [State Univ. of New York, Buffalo, NY (United States). Composite Materials Research Lab.

1996-10-01T23:59:59.000Z

283

Complete genome sequence of the filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus  

Science Journals Connector (OSTI)

The genome sequence of the filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus shows numerous distinctive features that may shine light on the origin and early evolution of photosynthesis.

Kuo-Hsiang Tang; Kerrie Barry; Olga Chertkov; Eileen Dalin; Cliff S Han; Loren J Hauser; Barbara M Honchak; Lauren E Karbach; Miriam L Land; Alla Lapidus; Frank W Larimer; Natalia Mikhailova; Samuel Pitluck; Beverly K Pierson; Robert E Blankenship

2011-06-29T23:59:59.000Z

284

Lateral downflows in sunspot penumbral filaments and their temporal evolution  

E-Print Network (OSTI)

We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited spectropolarimetric scans of the Fe I 6173 A line taken with the CRISP instrument at the Swedish 1-m Solar Telescope. We compute Dopplergrams from the observed intensity profiles using line bisectors and filter the resulting velocity maps for subsonic oscillations. Lateral downflows appear everywhere in the center-side penumbra as small, weak patches of redshifts next to or along the edges of blueshifted flow channels. These patches have an intermittent life and undergo mergings and fragmentations quite frequently. The lateral downflows move together with the hosting filaments and react to their shape variations, very much resembling the evolution of granular convection in the quiet Sun. There is a good relation between brightness and velocity of the flow structures in the center-side penumbra, wi...

Pozuelo, S Esteban; Rodriguez, J de la Cruz

2015-01-01T23:59:59.000Z

285

Coal fly ashcarbide lime bricks: An environment friendly building product  

Science Journals Connector (OSTI)

Abstract Coal fly ash and carbide lime are industrial by-products of coal combustion in thermal power plants and of manufacture of acetylene gas, respectively, available in profusion in southern Brazil. Research has been carried out to search for possible use of such materials to produce environmental friendly bricks that have high compressive strength. This study aims to evaluate strength controlling parameters of coal fly ashcarbide lime mixtures, as well as to show that porosity/carbide lime (?/Lv) ratio (corresponding to porosity divided by the volumetric carbide lime content) can be used to predict compressive strength (qu). The controlling parameters evaluated here are carbide lime content, porosity, curing temperature, curing time and porosity/carbide lime ratio. A number of unconfined compression tests were carried out. The results show that a power function adapts better the relation qu versus ?/Lv, in which Lv is adjusted by an exponent (in this case 0.11) for all coal fly ashcarbide lime mixtures studied. Equations that control the compressive strength for each curing period and curing temperature examined can be formulated using this unique ratio. Preferred strategies for varying ranges of qu are also proposed based on the energy required for heating, considering distinct curing periods and temperatures.

Nilo Cesar Consoli; Ceclia Gravina da Rocha; Rodrigo Beck Saldanha

2014-01-01T23:59:59.000Z

286

Targeted Genomic Deletion of the Lens-Specific Intermediate Filament Protein CP49  

E-Print Network (OSTI)

Targeted Genomic Deletion of the Lens-Specific Intermediate Filament Protein CP49 Azita Alizadeh,1, by blocking expression of the fiber cell­specific beaded filament protein CP49. METHODS. The first exon of the mouse CP49 gene was deleted by using targeted genomic deletion techniques. Gene deletion was assessed

Clark, John

287

RecA-mediated SOS induction requires an extended filament conformation but no ATP hydrolysis  

E-Print Network (OSTI)

RecA-mediated SOS induction requires an extended filament conformation but no ATP hydrolysis filament on single-stranded DNA and hydrolyzes ATP. The RecA K72R (recA2201) muta- tion eliminates in the presence of ATP. Strains with this mutation do not undergo SOS induction in vivo. We have combined the K72R

Cox, Michael M.

288

Metallic photonic-band-gap filament architectures for optimized incandescent lighting Sajeev John and Rongzhou Wang  

E-Print Network (OSTI)

Metallic photonic-band-gap filament architectures for optimized incandescent lighting Sajeev John occur 3,4 . Tra- ditionally incandescent lighting filaments, despite being driven from equilibrium the blackbody spectrum. This suggests the pos- sibility of higher efficiency incandescent lighting, through

John, Sajeev

289

Method for silicon carbide production by reacting silica with hydrocarbon gas  

DOE Patents (OSTI)

A method is described for producing silicon carbide particles using a silicon source material and a hydrocarbon. The method is efficient and is characterized by high yield. Finely divided silicon source material is contacted with hydrocarbon at a temperature of 400.degree. C. to 1000.degree. C. where the hydrocarbon pyrolyzes and coats the particles with carbon. The particles are then heated to 1100.degree. C. to 1600.degree. C. 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.

Glatzmaier, Gregory C. (Boulder, CO)

1994-01-01T23:59:59.000Z

290

SANS and TEM studies of carbide precipitation and creep damage in type 304 stainless steel  

SciTech Connect

Small-angle neutron scattering (SANS) and transmission electron microscopy (TEM) studies were performed to characterize the carbide (M/sub 23/C/sub 6/) precipitation and creep damage induced in type 304 stainless steel in the primary creep stage. The size distribution of matrix carbides evaluated from SANS analyses was consistent with TEM data, and the expected accelerated kinetics of precipitation under applied stress was confirmed. Additional SANS measurements after the postcreep solution annealing were made in order to differentiate cavities from the carbides. Potential advantages and difficulties associated with characterization of creep-induced cavitation by the SANS techniques are discussed.

Yoo, M.H.; Ogle, J.C.; Schneibel, J.H.; Swindeman, R.W.

1984-01-01T23:59:59.000Z

291

Initiation of a passivated interface between hafnium oxide and In(Ga)As(0 0 1)-(4x2)  

SciTech Connect

Hafnium oxide interfaces were studied on two related group III rich semiconductor surfaces, InAs(0 0 1)-(4x2) and In{sub 0.53}Ga{sub 0.47}As(0 0 1)-(4x2), via two different methods: reactive oxidation of deposited Hf metal and electron beam deposition of HfO{sub 2}. The interfaces were investigated with scanning tunneling microscopy and spectroscopy (STS). Single Hf atom chemisorption sites were identified that are resistant to oxidation by O{sub 2}, but Hf islands are reactive to O{sub 2}. After e{sup -} beam deposition of <<1 ML of HfO{sub 2}, single chemisorption sites were identified. At low coverage (<1 ML), the n-type and p-type HfO{sub 2}/InGaAs(0 0 1)-(4x2) interfaces show p-type character in STS, which is typical of clean InGaAs(0 0 1)-(4x2). After annealing below 200 deg. C, full coverage HfO{sub 2}/InGaAs(0 0 1)-(4x2) (1-3 ML) has the surface Fermi level shifted toward the conduction band minimum for n-type InGaAs, but near the valence band maximum for p-type InGaAs. This is consistent with the HfO{sub 2}/InGaAs(0 0 1)-(4x2) interface being at least partially unpinned, i.e., a low density of states in the band gap. The partially unpinned interface results from the modest strength of the bonding between HfO{sub 2} and InGaAs(0 0 1)-(4x2) that prevents substrate atom disruption. The fortuitous structure of HfO{sub 2} on InAs(0 0 1)-(4x2) and InGaAs(0 0 1)-(4x2) allows for the elimination of the partially filled dangling bonds on the surface, which are usually responsible for Fermi level pinning.

Clemens, Jonathon B.; Bishop, Sarah R.; Kummel, Andrew C. [Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Dr., 0358, La Jolla, California 92093-0358 (United States); Lee, Joon Sung [Department of Chemistry and Biochemistry/Materials Science and Engineering Program, University of California, San Diego, 9500 Gilman Dr., 0358, La Jolla, California 92093-0358 (United States); Droopad, Ravi [Department of Physics, Texas State University-San Marcos, San Marcos, Texas 78666 (United States)

2010-06-28T23:59:59.000Z

292

Role of ATP-hydrolysis in the dynamics of a single actin filament  

E-Print Network (OSTI)

We study the stochastic dynamics of growth and shrinkage of single actin filaments taking into account insertion, removal, and ATP hydrolysis of subunits either according to the vectorial mechanism or to the random mechanism. In a previous work, we developed a model for a single actin or microtubule filament where hydrolysis occurred according to the vectorial mechanism: the filament could grow only from one end, and was in contact with a reservoir of monomers. Here we extend this approach in several ways, by including the dynamics of both ends and by comparing two possible mechanisms of ATP hydrolysis. Our emphasis is mainly on two possible limiting models for the mechanism of hydrolysis within a single filament, namely the vectorial or the random model. We propose a set of experiments to test the nature of the precise mechanism of hydrolysis within actin filaments.

Padinhateeri Ranjith; Kirone Mallick; Jean-Francois Joanny; David Lacoste

2010-01-07T23:59:59.000Z

293

Autonomous Motility of Active Filaments due to Spontaneous Flow-Symmetry Breaking  

E-Print Network (OSTI)

We simulate the nonlocal Stokesian hydrodynamics of an elastic filament which is active due a permanent distribution of stresslets along its contour. A bending instability of an initially straight filament spontaneously breaks flow symmetry and leads to autonomous filament motion which, depending on conformational symmetry, can be translational or rotational. At high ratios of activity to elasticity, the linear instability develops into nonlinear fluctuating states with large amplitude deformations. The dynamics of these states can be qualitatively understood as a superposition of translational and rotational motion associated with filament conformational modes of opposite symmetry. Our results can be tested in molecular-motor filament mixtures, synthetic chains of autocatalytic particles, or other linearly connected systems where chemical energy is converted to mechanical energy in a fluid environment.

Gayathri Jayaraman; Sanoop Ramachandran; Somdeb Ghose; Abhrajit Laskar; M. Saad Bhamla; P. B. Sunil Kumar; R. Adhikari

2012-10-10T23:59:59.000Z

294

Silicon carbide tritium permeation barrier for steel structural components.  

SciTech Connect

Chemical vapor deposited (CVD) silicon carbide (SiC) has superior resistance to tritium permeation even after irradiation. Prior work has shown Ultrametfoam to be forgiving when bonded to substrates with large CTE differences. The technical objectives are: (1) Evaluate foams of vanadium, niobium and molybdenum metals and SiC for CTE mitigation between a dense SiC barrier and steel structure; (2) Thermostructural modeling of SiC TPB/Ultramet foam/ferritic steel architecture; (3) Evaluate deuterium permeation of chemical vapor deposited (CVD) SiC; (4) D testing involved construction of a new higher temperature (> 1000 C) permeation testing system and development of improved sealing techniques; (5) Fabricate prototype tube similar to that shown with dimensions of 7cm {theta} and 35cm long; and (6) Tritium and hermeticity testing of prototype tube.

Causey, Rion A. (Sandia National Laboratories, Livermore, CA); Garde, Joseph Maurico; Buchenauer, Dean A. (Sandia National Laboratories, Livermore, CA); Calderoni, Pattrick (Idaho National Laboratory); Holschuh, Thomas, Jr.; Youchison, Dennis Lee; Wright, Matt; Kolasinski, Robert D. (Sandia National Laboratories, Livermore, CA)

2010-09-01T23:59:59.000Z

295

High surface area silicon carbide-coated carbon aerogel  

SciTech Connect

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.

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

2014-01-14T23:59:59.000Z

296

DECODING THE MESSAGE FROM METEORITIC STARDUST SILICON CARBIDE GRAINS  

SciTech Connect

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.

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

297

Decoding the message from meteoritic stardust silicon carbide grains  

E-Print Network (OSTI)

Micron-sized stardust grains that originated in ancient stars are recovered from meteorites and analysed using high-resolution mass spectrometry. The most widely studied type of stardust is silicon carbide (SiC). Thousands of these grains have been analysed 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 carry 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 modelling of dust condensation in stellar winds as function of the metallicity.

Lewis, Karen M; Gibson, Brad K; Pilkington, Kate

2013-01-01T23:59:59.000Z

298

Electron Spin Decoherence in Silicon Carbide Nuclear Spin Bath  

E-Print Network (OSTI)

In this paper, we study the electron spin decoherence of single defects in silicon carbide (SiC) nuclear spin bath. We find that, although the natural abundance of $^{29}\\rm{Si}$ ($p_{\\rm{Si}}=4.7\\%$) is about 4 times larger than that of $^{13}{\\rm C}$ ($p_{\\rm{C}}=1.1\\%$), the electron spin coherence time of defect centers in SiC nuclear spin bath in strong magnetic field ($B>300~\\rm{Gauss}$) is longer than that of nitrogen-vacancy (NV) centers in $^{13}{\\rm C}$ nuclear spin bath in diamond. The reason for this counter-intuitive result is the suppression of heteronuclear-spin flip-flop process in finite magnetic field. Our results show that electron spin of defect centers in SiC are excellent candidates for solid state spin qubit in quantum information processing.

Li-Ping Yang; Christian Burk; Mattias Widmann; Sang-Yun Lee; Jrg Wrachtrup; Nan Zhao

2014-09-16T23:59:59.000Z

299

Advanced Measurements of Silicon Carbide Ceramic Matrix Composites  

SciTech Connect

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.

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

2012-08-01T23:59:59.000Z

300

Force generation by Myosin II Filaments in Compliant Networks  

E-Print Network (OSTI)

Myosin II isoforms with varying mechanochemistry and filament size interact with filamentous actin (F-actin) networks to generate contractile forces in cells. How their properties control force production in environments with varying stiffness is poorly understood. Here, we incorporated literature values for properties of myosin II isoforms into a cross-bridge model. Similar actin gliding speeds and force-velocity curves expected from previous experiments were observed. Motor force output on an elastic load was regulated by two timescales--that of their attachment to F-actin, which varied sharply with the ensemble size, motor duty ratio, and external load, and that of force build up, which scaled with ensemble stall force, gliding speed, and load stiffness. While such regulation did not require force-dependent kinetics, the myosin catch bond produced positive feedback between attachment time and force to trigger switch-like transitions from short attachments and small forces to high force-generating runs at threshold parameter values. Parameters representing skeletal muscle myosin, non-muscle myosin IIB, and non-muscle myosin IIA revealed distinct regimes of behavior respectively: (1) large assemblies of fast, low-duty ratio motors rapidly build stable forces over a large range of environmental stiffness, (2) ensembles of slow, high-duty ratio motors serve as high-affinity cross-links with force build-up times that exceed physiological timescales, and (3) small assemblies of low-duty ratio motors operating at intermediate speeds may respond sharply to changes in mechanical context--at low forces or stiffness, they serve as low affinity cross-links but they can transition to effective force production via the positive feedback mechanism described above. These results reveal how myosin isoform properties may be tuned to produce force and respond to mechanical cues in their environment.

Samantha Stam; Jon Alberts; Margaret L. Gardel; Edwin Munro

2014-07-08T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

PRELIMINARY SURVEY OF THE UNION CARBIDE CORPORATION METALS DIVISION PLANT, NIAGARA FALLS, NEW YORK  

Office of Legacy Management (LM)

e e - .' N"lr 7% PRELIMINARY SURVEY OF THE UNION CARBIDE CORPORATION METALS DIVISION PLANT, NIAGARA FALLS, NEW YORK Work performed by the Health and Safety Research Division Oak Ridge Natjonal Laboratory Oak Ridge, Tennessee 37830 December 1980 OAK RIDGE NATIONAL LABORATORY operated by UNION CARBIDE CORPORATION for the DEPARTMENT OF ENERGY as part of the Formerly Utilized Sites-- Remedial Action Program PRELIMINARY SURVEY OF THE UNION CARBIDE CORPORATION METALS DIVISION PLANT, NIAGARA FALLS, NEW YORK B. A. Berven and R. W. Doane Introduction On September 2;, 1980, two representatives from Oak Ridge National Laboratory visited Union Carbide Corporation's Metal Division Plant (UCC-MD) in Niagara Falls, New York. The purpose of the visit was to

302

Analysis of silicon carbide based semiconductor power devices and their application in power factor correction  

E-Print Network (OSTI)

cannot handle. The requirements include higher blocking voltages, switching frequencies, efficiency, and reliability. Material technologies superior to Si are needed for future power device developments. Silicon Carbide (SiC) based semiconductor devices...

Durrani, Yamin Qaisar

2005-11-01T23:59:59.000Z

303

Preliminary study of neutron absorption by concrete with boron carbide addition  

SciTech Connect

Concrete has become a conventional material in construction of nuclear reactor due to its properties like safety and low cost. Boron carbide was added as additives in the concrete construction as it has a good neutron absorption property. The sample preparation for concrete was produced with different weight percent of boron carbide powder content. The neutron absorption rate of these samples was determined by using a fast neutron source of Americium-241/Be (Am-Be 241) and detection with a portable backscattering neutron detector. Concrete with 20 wt % of boron carbide shows the lowest count of neutron transmitted and this indicates the most neutrons have been absorbed by the concrete. Higher boron carbide content may affect the concrete strength and other properties.

Abdullah, Yusof, E-mail: yusofabd@nuclearmalaysia.gov.my; Yusof, Mohd Reusmaazran; Zali, Nurazila Mat; Ahmad, Megat Harun Al Rashid Megat; Yazid, Hafizal [Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Ariffin, Fatin Nabilah Tajul; Ahmad, Sahrim [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Hamid, Roszilah [Department of Civil and Structural Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Mohamed, Abdul Aziz [College of Engineering, Universiti Tenaga National, Jalan Ikram-Uniten, 43000 Kajang, Selangor (Malaysia)

2014-02-12T23:59:59.000Z

304

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

E-Print Network (OSTI)

This report presents a survey of the author's internship experience with Union Carbide Corporation's Texas City plant during the period July 1, 1980 through May 15, 1981. The ten and one-half month internship was spent as an engineering...

Tippett, Donald Dwight, 1947-

2013-03-13T23:59:59.000Z

305

High-Temperature Oxidation Resistance of Refractory Silicon NitrideSilicon Carbide Materials  

Science Journals Connector (OSTI)

Silicon nitride and carbide are promising materials for use as refractories; they are highly resistant to mineral acids and alkalis, have a high melting point, and are thermally very stable [1].

I. N. Godovannaya; O. I. Popova

1972-01-01T23:59:59.000Z

306

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

DOE Patents (OSTI)

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.

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

2004-07-20T23:59:59.000Z

307

E-Print Network 3.0 - aluminide-bonded carbide ceramics Sample...  

NLE Websites -- All DOE Office Websites (Extended Search)

R. Begleyw Summary: include TBCs on superalloys, EBCs on sili- con-based ceramics, or TiCNbN coatings on cemented carbide... with Diffusion Aluminide Bond Coatings,'' Mater....

308

E-Print Network 3.0 - aluminium carbides Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

temperatures. In the industrialproduction of A1203on cemented carbide cutting tools... TiCA1,03 interfaces have shown that aluminium oxide samples with good adhesionare Article...

309

Characteristics of 6H-silicon carbide PIN diodes prototyping by laser doping  

Science Journals Connector (OSTI)

Silicon carbide PIN diodes have been fabricated using a direct-write laser-doping technique that reduces defect generation compared to the conventional ion-implantation technique. Nitrogen and aluminum were su...

Z. Tian; N. R. Quick; A. Kar

2005-01-01T23:59:59.000Z

310

Measurements of the Motion of Plasma Filaments in a Plasma Ball  

SciTech Connect

Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ~106 cm/sec at the driving frequency of ~26 kHz, and drift upward through the ball at ~1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.

M. Campanell, J. Laird, T. Provost, S. Vasquez, S.J. Zweben

2010-01-26T23:59:59.000Z

311

Effect of WC/TiC grain size ratio on microstructure and mechanical properties of WCTiCCo cemented carbides  

E-Print Network (OSTI)

of TiC powder as 1 lm. The microstructures of sintered WC­TiC­10 wt%Co cemented carbides were than that expected by modified Hall­Petch type equation. Transverse rupture strength of WC­20TiC­10 wt for decades [1]. Generally, cemented carbides are based on the WC­Co and some cubic carbide such as TiC, Ta

Hong, Soon Hyung

312

Biofuels production from hydrotreating of vegetable oil using supported noble metals, and transition metal carbide and nitride.  

E-Print Network (OSTI)

?? The focus of this research is to prepare non-sulfided hydrotreating catalysts, supported noble metal and transition metal carbide/ nitride, and evaluate their hydrocracking activities (more)

Wang, Huali

2012-01-01T23:59:59.000Z

313

Developing a High Thermal Conductivity Fuel with Silicon Carbide Additives  

SciTech Connect

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 1,377C, 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 1,300C:

Ronald baney; James Tulenko

2012-11-20T23:59:59.000Z

314

USE OF SILICON CARBIDE MONITORS IN ATR IRRADIATION TESTING  

SciTech Connect

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 200C and 800C. 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.

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

2012-07-01T23:59:59.000Z

315

Silicon Carbide Photonic Crystal Cavities with Integrated Color Centers  

E-Print Network (OSTI)

The recent discovery of color centers with optically addressable spin states in 3C silicon carbide (SiC) similar to the negatively charged nitrogen vacancy center in diamond has the potential to enable the integration of defect qubits into established wafer scale device architectures for quantum information and sensing applications. Here we demonstrate the design, fabrication, and characterization of photonic crystal cavities in 3C SiC films with incorporated ensembles of color centers and quality factor (Q) to mode volume ratios similar to those achieved in diamond. Simulations show that optimized H1 and L3 structures exhibit Q as high as 45,000 and mode volumes of approximately (\\lambda/n). We utilize the internal color centers as a source of broadband excitation to characterize fabricated structures with resonances tuned to the color center zero phonon line and observe Q in the range of 900-1,500 with narrowband photoluminescence collection enhanced by up to a factor of 10. By comparing the Q factors obser...

Calusine, Greg; Awschalom, David D

2014-01-01T23:59:59.000Z

316

Nano-precipitation in hot-pressed silicon carbide  

SciTech Connect

Heat treatments at 1300 degrees C, 1400 degrees C, 1500 degrees C, and 1600 degrees C in Ar were found to produce nanoscale precipitates in hot-pressed silicon carbide containing aluminum, boron, and carbon sintering additives (ABC-SiC). The precipitates were studied by transmission electron microscopy (TEM) and nano-probe energy-dispersive X-ray spectroscopy (nEDS). The precipitates were plate-like in shape, with a thickness, length and separation of only a few nanometers, and their size coarsened with increasing annealing temperature, accompanied by reduced number density. The distribution of the precipitates was uniform inside the SiC grains, but depleted zones were observed in the vicinity of the SiC grain boundaries. A coherent orientation relationship between the precipitates and the SiC matrix was found. Combined high-resolution electron microscopy, computer simulation, and nEDS identified an Al4C3-based structure and composition for the nano-precipitates. Most Al ions in SiC lattice exsolved as precipitates during the annealing at 1400 to 1500 degrees C. Formation mechanism and possible influences of the nanoscale precipitates on mechanical properties are discussed.

Zhang, Xiao Feng; Sixta, Mark E.; Chen, Da; De Jonghe, Lutgard C.

2000-05-16T23:59:59.000Z

317

Silicon Carbide Photonic Crystal Cavities with Integrated Color Centers  

E-Print Network (OSTI)

The recent discovery of color centers with optically addressable spin states in 3C silicon carbide (SiC) similar to the negatively charged nitrogen vacancy center in diamond has the potential to enable the integration of defect qubits into established wafer scale device architectures for quantum information and sensing applications. Here we demonstrate the design, fabrication, and characterization of photonic crystal cavities in 3C SiC films with incorporated ensembles of color centers and quality factor (Q) to mode volume ratios similar to those achieved in diamond. Simulations show that optimized H1 and L3 structures exhibit Q as high as 45,000 and mode volumes of approximately $(\\lambda/n)^{3}$. We utilize the internal color centers as a source of broadband excitation to characterize fabricated structures with resonances tuned to the color center zero phonon line and observe Q in the range of 900-1,500 with narrowband photoluminescence collection enhanced by up to a factor of 10. By comparing the Q factors observed for different geometries with finite-difference time-domain simulations, we find evidence that nonvertical sidewalls are likely the dominant source of discrepancies between our simulated and measured Q factors. These results indicate that defect qubits in 3C SiC thin films show clear promise as a simple, scalable platform for interfacing defect qubits with photonic, optoelectronic, and optomechanical devices.

Greg Calusine; Alberto Politi; David D. Awschalom

2014-05-20T23:59:59.000Z

318

ETOILE Regulates Developmental Patterning in the Filamentous Brown Alga Ectocarpus siliculosus  

Science Journals Connector (OSTI)

...initially obtained from the automated annotation of the E...mutant leads to the rapid induction of the branching...filament. Computational modeling allowed the simulation of the etl mutant phenotype...Segregation genetics Computer Simulation Crosses, Genetic Genes...

Aude Le Bail; Bernard Billoud; Sophie Le Panse; Sabine Chenivesse; Bénédicte Charrier

2011-04-08T23:59:59.000Z

319

Diamond growth with CF4 addition inhot-filament chemical vapour deposition  

Science Journals Connector (OSTI)

Tetrafluoromethane (CF4) was added to standard CH4/H2 mixtures ... in hot-filament-assisted chemical vapour deposition. CF4 concentrations in the range of 0.3% ... a small fraction (CF4 was thermally di...

E. J CORAT; V. J TRAVA-AIROLDI; N. F LEITE; M. C. A NONO

320

The splitted laser beam filamentation in interaction of laser and an exponential decay inhomogeneous underdense plasma  

SciTech Connect

The splitted beam filamentation in interaction of laser and an exponential decay inhomogeneous underdense plasma is investigated. Based on Wentzel-Kramers-Brillouin (WKB) approximation and paraxial/nonparaxial ray theory, simulation results show that the steady beam width and single beam filamentation along the propagation distance in paraxial case is due to the influence of ponderomotive nonlinearity. In nonparaxial case, the influence of the off-axial of {alpha}{sub 00} and {alpha}{sub 02} (the departure of the beam from the Gaussian nature) and S{sub 02} (the departure from the spherical nature) results in more complicated ponderomotive nonlinearity and changing of the channel density and refractive index, which led to the formation of two/three splitted beam filamentation and the self-distortion of beam width. In addition, influence of several parameters on two/three splitted beam filamentation is discussed.

Xia Xiongping; Yi Lin [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Xu Bin [Department of Mathematics and Information Sciences, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Lu Jianduo [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Hubei Province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081 (China)

2011-10-15T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

The cytoskeleton is composed of polymeric filaments that provide architectural support and also participate  

E-Print Network (OSTI)

migration, and the out- growth of cellular processes (Schmit and Lambert 1988; Tanaka and Kirschner 1991 are interrelated, such that the dynamics of one type of filament can affect the dynam- ics of the other (Lin

Baas, Peter W.

322

Magnetism in hafnium dioxide  

Science Journals Connector (OSTI)

Thin films of HfO2 produced by pulsed-laser deposition on sapphire, yttria-stabilized zirconia, or silicon substrates show ferromagnetic magnetization curves with little hysteresis and extrapolated Curie temperatures far in excess of 400K. The moment does not scale with film thickness, but in terms of substrate area it is typically in the range 150400?Bnm?2. The magnetization exhibits a remarkable anisotropy, which depends on texture and substrate orientation. Pure HfO2 powder develops a weak magnetic moment on heating in vacuum, which is eliminated on annealing in oxygen. Lattice defects are the likely source of the magnetism.

J. M. D. Coey; M. Venkatesan; P. Stamenov; C. B. Fitzgerald; L. S. Dorneles

2005-07-22T23:59:59.000Z

323

HUBBLE SPACE TELESCOPE OBSERVATIONS OF DUSTY FILAMENTS IN HERCULES A: EVIDENCE FOR ENTRAINMENT  

SciTech Connect

We present U-, V-, and I-band images of the host galaxy of Hercules A (3C 348) obtained with HST/WFC3/UVIS. We find a network of dusty filaments which are more complex and extended than seen in earlier Hubble Space Telescope (HST) observations. The filaments are associated with a faint blue continuum light (possibly from young stars) and faint H{alpha} emission. It seems likely that the cold gas and dust has been stripped from a companion galaxy now seen as a secondary nucleus. There are dusty filaments aligned with the base of the jets on both eastern and western sides of the galaxy. The morphology of the filaments is different on the two sides-the western filaments are fairly straight, while the eastern filaments are mainly in two loop-like structures. We suggest that despite the difference in morphologies, both sets of filaments have been entrained in a slow-moving boundary layer outside the relativistic flow. As suggested by Fabian et al., magnetic fields in the filaments may stabilize them against disruption. We consider a speculative scenario to explain the relation between the radio source and the shock and cavities in the hot intracluster medium seen in the Chandra data. We suggest that the radio source originally ({approx}60 Myr ago) propagated along a position angle of {approx}35 Degree-Sign where it created the shock and cavities. The radio source axis changed to its current orientation ({approx}100 Degree-Sign ) possibly due to a supermassive black hole merger and began its current epoch of activity about 20 Myr ago.

O'Dea, C. P.; Kharb, P. [School of Physics and Astronomy, and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 84 Lomb Memorial Dr., Rochester, NY 14623 (United States); Baum, S. A. [Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 84 Lomb Memorial Dr., Rochester, NY 14623 (United States); Tremblay, G. R. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Muenchen (Germany); Cotton, W. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Perley, R. [National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 (United States)

2013-07-01T23:59:59.000Z

324

Fine-scale structures and material flows of quiescent filaments observed by New Vacuum Solar Telescope  

E-Print Network (OSTI)

Study on the small-scale structures and material flows of solar quiescent filaments is very important for understanding the formation and equilibrium of solar filaments. Using the high resolution H{\\alpha} data observed by the New Vacuum Solar Telescope (NVST), we present the structures of the barbs and the material flows along the threads across the spine in two quiescent filaments on 2013 September 29 and on 2012 November 2, respectively. During the evolution of the filament barb, several parallel tube-shaped structures formed and the width of the structures ranges from about 2.3 Mm to 3.3 Mm. The parallel tube-shaped structures merged together accompanied with the material flows from the spine to the barb. Moreover, the boundary between the barb and surrounding atmosphere is very neat. The counter-streaming flows were not found to appear alternately in the adjacent threads of the filament. However, the large-scale patchy counter-streaming flows are detected in the filament. The flows in one patch of the fi...

Yan, X L; Xiang, Y Y; Yang, L H

2015-01-01T23:59:59.000Z

325

Influence Of Ultrasonic Waves On The Formation Of High Pores Silicon Carbide  

SciTech Connect

The Challenge to produce a quality Silicon Carbide that combination high surface area is promising and this material can be used in many application such as Hydrogen storage materials. Synthesis of high surface area carbon materials by selective etching of Silicon Carbide with choric acid while exposing ultrasonic wave have been made.Powder Of Sic (surface area 17.8 m{sup 2}/g) was treated in the chloric acetic as well as their mixture of various compositions and various time exposure of ultrasonic waves. Surface area and pore size can be controlled by temperature and concentration composition of Chloric and time exposure of ultrasonic wave.The resultant carbon and carbon-silicon carbide composite powders were characterized X-ray diffraction and Electron microscope. To determine a conversion degree of silicon carbide due to influence of the ultrasonic wave, the samples were annealed in open air at 1000 deg. C. There by carbon component of the carbon/silicon carbide composite was completely oxidized. The analysis of the samples shows the strong influence of time exposure of ultrasonic waves on the formation of pores.

Toana, Musfirah C. F. [Physics Dept. University of Tadulako (Indonesia); Soegijono, B.; Hikam, M. [Physics Dept. University of Indonesia (Indonesia)

2009-09-14T23:59:59.000Z

326

The interaction of polarized microwaves with planar arrays of femtosecond laser-produced plasma filaments in air  

SciTech Connect

The interaction of polarized microwaves with subwavelength arrays of parallel plasma filaments, such as those produced by the propagation of high-power femtosecond laser pulses in ambient air, was investigated by calculating the reflection and transmission coefficients as a function of the incidence angles using the finite-difference time-domain (FDTD) method. The time evolution of these coefficients was calculated and compared with experiments. It is found that the plasma filaments array becomes transparent when the polarization of the microwave radiation is perpendicular to the filaments axis, regardless the incidence angle of the microwave with respect to the filaments, except near grazing incidence. Increasing the filaments electron density or diameter, or decreasing the electron collision frequency or filaments spacing, decreases the transmission and increases the reflection. Transmission decreases when increasing the number of filament layers while reflection remains unchanged as the number of filament layers exceeds a given number ({approx}3 in our case). Transmission slightly increases when disorder is introduced in the filament arrays. The detailed calculation results are compared with those obtained from the simple birefringent slab model, which provides a convenient framework to calculate approximately the properties of filament arrays.

Marian, Anca; El Morsli, Mbark; Vidal, Francois; Payeur, Stephane; Kieffer, Jean-Claude [INRS-Energie, Materiaux et Telecommunications, Universite du Quebec, Varennes, Quebec J3X 1S2 (Canada); Chateauneuf, Marc; Theberge, Francis; Dubois, Jacques [Defense R and D Canada Valcartier, Quebec G3J 1X5 (Canada)

2013-02-15T23:59:59.000Z

327

The role of oxygen in hydrogen sensing by a platinum-gate silicon carbide gas sensor: An ultrahigh vacuum study  

E-Print Network (OSTI)

The role of oxygen in hydrogen sensing by a platinum-gate silicon carbide gas sensor: An ultrahigh conditions that elucidate the role of oxygen in the functioning of silicon carbide field-effect gas sensors hydrogen-depleted state; competition between hydrogen oxidation and hydrogen diffusion to metal/ oxide

Tobin, Roger G.

328

Materials Science and Engineering A244 (1998) 138144 The vacuum hot pressing behavior of silicon carbide fibers coated  

E-Print Network (OSTI)

carbide fibers coated with nanocrystalline Ti­6Al­4V Joseph M. Kunze *, Haydn N.G. Wadley Intelligent (VHP) of silicon carbide monofilaments coated with nanocrystalline Ti­6Al­4V has been studied. During micromechanical contact analysis for a metal coated fiber. Final stage densification was analyzed by modifying

Wadley, Haydn

329

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

E-Print Network (OSTI)

.V. All rights reserved. 1. Introduction Transition metal carbides (TMCs), typically including all 3 d ele- ments and 4 d/5 d elements of groups 3­6 early transition metals, possess unique physical and chemicalStructural and electronic properties of cobalt carbide Co2C and its surface stability: Density

Li, Weixue

330

Damages induced by heavy ions in titanium silicon carbide: effects of nuclear and electronic interactions at room temperature  

E-Print Network (OSTI)

, of general formula Mn+1AXn where n = {1,2,3}, M is an early transition metal, A is an A-group (mostly IIIADamages induced by heavy ions in titanium silicon carbide: effects of nuclear and electronic Thanks to their refractoriness, carbides are sensed as fuel coating for the IVth generation of reactors

Paris-Sud XI, Université de

331

13C and 15N N.M.R. in thorium carbides and carbonitrides J. L. Boutard (*),  

E-Print Network (OSTI)

) of 8.4 (i.e. ThCo.6No.4). In transition metal carbides and nitrides, a similar but more pronounced in the corresponding transition metal systems since y(ThC) = 2.12 m845 13C and 15N N.M.R. in thorium carbides and carbonitrides J. L. Boutard (*), SFMA, DECPu, Centre

Paris-Sud XI, Université de

332

DOE - Office of Legacy Management -- Union Carbide and Carbon Co - TN 10  

Office of Legacy Management (LM)

Carbide and Carbon Co - TN 10 Carbide and Carbon Co - TN 10 FUSRAP Considered Sites Site: Union Carbide and Carbon Co (TN.10) Designated Name: Alternate Name: Location: Evaluation Year: Site Operations: Site Disposition: Radioactive Materials Handled: Primary Radioactive Materials Handled: Radiological Survey(s): Site Status: This site is one of a group of 5 FUSRAP considered sites for which records are available that provide a reasonably complete historical account of their operations and relationship, if any, with MED/AEC operations. However, additional analyses of these historical records, and more recent documentation of decisions concerning the authority and other considerations related to the elimination of these sites from further consideration under FUSRAP is warranted. These analyses will provide the

333

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

DOE Patents (OSTI)

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.

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

2013-01-22T23:59:59.000Z

334

Glycerol electrooxidation on highly active Pd supported carbide/C aerogel composites catalysts  

Science Journals Connector (OSTI)

The nanosized carbide supported on carbon aerogel composites have been synthesized by polycondensation of resorcinol and formaldehyde (RF) method in the presence of sodium tungstate and sodium molybdate. The materials are characterized by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy (EDS), and cyclic voltammetry. The Pd nanoparticles supported on binary-carbide and carbon aerogel composites (Pd@WC-Mo2C/C) for glycerol oxidation are investigated for the first time. The Pd@WC-Mo2C/C as electrocatalyst shows a superior activity toward the glycerol oxidation in terms of the peak current density, which is almost two times higher than that of Pd/C and show better poison-resistant ability. The binary transition-metal carbide will be the potential catalyst support for the direct alcohol fuel cells.

Xiaofei Zhang; Pei Kang Shen

2013-01-01T23:59:59.000Z

335

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

E-Print Network (OSTI)

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.

Vojvodic, Aleksandra

2009-01-01T23:59:59.000Z

336

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Silicon Carbide Technology Breakthrough Silicon Carbide Technology Breakthrough Silicon carbide (SiC) is a semiconductor material under rapid development for use in power electronic (PE) systems due to its unique material and electronic properties. SiC potentially offers several advantages over conventional silicon (Si) for use in PE devices. Comparatively, individual SiC devices (in theory) can endure temperatures up to 600°C (standard Si PE devices are typically limited to 150°C), withstand more voltage, tolerate a larger current density, and operate at a higher frequency. This augmented performance of SiC devices in turn leads to PE devices that are significantly more energy efficient in their operation. Research and development is ongoing to produce SiC PE products with higher currents

337

Carbide-Derived Nanoporous Carbon and Novel Core-Shell Xinqi Chen, Donald R. Cantrell, Kevin Kohlhaas, Sasha Stankovich, James A. Ibers,  

E-Print Network (OSTI)

of metal carbides by halogens. In this process, metal is extracted preferentially by the halogenCarbide-Derived Nanoporous Carbon and Novel Core-Shell Nanowires Xinqi Chen, Donald R. Cantrell, 2005. ReVised Manuscript ReceiVed NoVember 29, 2005 Carbide-derived carbon (CDC) nanowires (NWs) have

338

Published in 'Silicon Carbide, III-Nitrides and Related Materials', Year: 1998, pp: 829-832 Periodical: Materials Science Forum Vols. 264-268  

E-Print Network (OSTI)

Published in 'Silicon Carbide, III-Nitrides and Related Materials', Year: 1998, pp: 829@scientific.net © 1998 by Trans Tech Publications Ltd., Switzerland, http://www.ttp.net #12;Published in 'Silicon Carbide Publications Ltd., Switzerland, http://www.ttp.net #12;Published in 'Silicon Carbide, III-Nitrides and Related

Steckl, Andrew J.

339

Nuclear Instruments and Methods in Physics Research A 562 (2006) 380388 Modeling solid-state boron carbide low energy neutron detectors  

E-Print Network (OSTI)

carbide low energy neutron detectors C. Lundstedta,b , A. Harkena,c , E. Daya,c , B.W. Robertsona,c , S types of solid-state boron carbide detector. These results provide the basis for distinguishing between-section. At the University of Nebraska, Lincoln (UNL), a semiconducting form of boron carbide has been developed over

340

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)

­Au alloy catalyst resist carbide formation? Y.-F. Han, D. Kumar, C. Sivadinarayana, A. Clearfield, and D October 2003; accepted 24 February 2004 The formation of Pd carbide (PdCx) during the synthesis of vinyl­Au/SiO2; XRD. 1. Introduction The formation of carbides over supported Pd catalysts was first reported

Goodman, Wayne

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Formation energy of -carbide using ab initio calculations Seung-Woo Seo, You Young Song, In Gee Kim, H. K. D. H. Bhadeshia  

E-Print Network (OSTI)

Formation energy of -carbide using ab initio calculations Seung-Woo Seo, You Young Song, In Gee Kim(Fe,Mn)3C with an anti-perovskite structure, known as -carbide, is easily found in strong, low is enhanced by the precipitation of -carbide, which is coherent with austenite, causes a shear band induced

Cambridge, University of

342

In vitro cellular responses to silicon carbide particles manufactured through the Acheson process: impact of physico-chemical features on pro-inflammatory and pro-  

E-Print Network (OSTI)

1 In vitro cellular responses to silicon carbide particles manufactured through the Acheson process ROS: Reactive Oxygen Species SiC: Silicon carbide SSA: Specific Surface Area TNF: Tumor Necrosis carbide (SiC) an industrial-scale product manufactured through the Acheson process, is largely employed

Paris-Sud XI, Université de

343

Published in 'Silicon Carbide and Related Materials -1999', Year: 2000, pp: 273-276 Periodical: Materials Science Forum Vols. 338-342  

E-Print Network (OSTI)

Published in 'Silicon Carbide and Related Materials - 1999', Year: 2000, pp: 273-276 Periodical@scientific.net © 2000 by Trans Tech Publications Ltd., Switzerland, http://www.ttp.net #12;Published in 'Silicon Carbide., Switzerland, http://www.ttp.net #12;Published in 'Silicon Carbide and Related Materials - 1999', Year: 2000

Steckl, Andrew J.

344

Molecular dynamics simulations of hydrogen bombardment of tungsten carbide surfaces P. Trskelin,1 N. Juslin,1 P. Erhart,2 and K. Nordlund1  

E-Print Network (OSTI)

Molecular dynamics simulations of hydrogen bombardment of tungsten carbide surfaces P. Träskelin,1 and tungsten carbide WC is of interest both due to the use of hydrogen-containing plasmas in thin. INTRODUCTION Tungsten carbide WC exhibits extraordinary hardness and temperature resistance. It has long been

Nordlund, Kai

345

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

E-Print Network (OSTI)

Journal of Physics and Chemistry of Solids 67 (2006) 2512­2516 Crystal chemistry of layered carbide structure of a layered ternary carbide, Ti3(Si0.43Ge0.57)C2, was studied with single-crystal X structure 1. Introduction Layered carbides and nitrides, or the so-called Mn+1AXn (MAX) phases, where n is 1

Downs, Robert T.

346

Electronic and dynamic studies of boron carbide nanowires D. N. McIlroy, Daqing Zhang, Robert M. Cohen, and J. Wharton  

E-Print Network (OSTI)

Electronic and dynamic studies of boron carbide nanowires D. N. McIlroy, Daqing Zhang, Robert M and vibrational properties of boron carbide nanowires grown by plasma-enhanced chemical vapor deposition have been. The NEXAFS spectra are equivalent to corresponding spectra of single-crystal (B4C) boron carbide, consistent

Gilbert, Pupa Gelsomina De Stasio

347

Phosphorus carbides: theory and experiment F. Claeyssens, G. M. Fuge, N. L. Allan, P. W. May and M. N. R. Ashfold  

E-Print Network (OSTI)

Phosphorus carbides: theory and experiment F. Claeyssens, G. M. Fuge, N. L. Allan, P. W. May and M ratios 3 has served to trigger further research into new `phosphorus carbide' materials. Theoretical) The electronic structure and stability of different crystalline phosphorus carbide PxCy phases have been studied

Bristol, University of

348

Published in 'Silicon Carbide, III-Nitrides and Related Materials', Year: 1998, pp: 1149-1152 Periodical: Materials Science Forum Vols. 264-268  

E-Print Network (OSTI)

Published in 'Silicon Carbide, III-Nitrides and Related Materials', Year: 1998, pp: 1149@scientific.net © 1998 by Trans Tech Publications Ltd., Switzerland, http://www.ttp.net #12;Published in 'Silicon Carbide Publications Ltd., Switzerland, http://www.ttp.net #12;Published in 'Silicon Carbide, III-Nitrides and Related

Steckl, Andrew J.

349

ELSEVIER Joumal of Organometallic Chemistry 520 (1996) 227-230 The Union Carbide catalyst(Cp Cr + SiO2),  

E-Print Network (OSTI)

ELSEVIER Joumal of Organometallic Chemistry 520 (1996) 227- 230 o oumal Chemistry The Union Carbide-chemisches lnstitutder TUMfinchen,85747Garching,Germany Received 27 February 1996 Abstract The Union Carbide catalyst characteristics. Keywords: Solid-state NMR spectroscopy; Union Carbide catalyst; Chromium; Chromocenes

Bluemel, Janet

350

Solid phosphorus carbide? Frederik Claeyssens,a Neil L. Allan,*a Paul W. May,a Pablo Ordejnb and Josep M. Olivab  

E-Print Network (OSTI)

Solid phosphorus carbide? Frederik Claeyssens,a Neil L. Allan,*a Paul W. May,a Pablo Ordejónb The electronic structure of different phosphorus carbide solid phases with stoichiometry P4C3 is studied using these films `doped DLC'--instead, they have been termed `amorphous phosphorus carbide'. For many semiconductor

Bristol, University of

351

The near-edge structure in energy-loss spectroscopy: many-electron and magnetic effects in transition metal nitrides and carbides  

E-Print Network (OSTI)

in transition metal nitrides and carbides This article has been downloaded from IOPscience. Please scroll down-loss spectroscopy: many-electron and magnetic effects in transition metal nitrides and carbides A T Paxton, M van energies are systematically overestimated by 4.22 ± 0.44 eV in twelve transition metal carbides

Paxton, Anthony T.

352

Electronic structure of the 4d transition metal carbides: Dispersed fluorescence spectroscopy of MoC, RuC, and PdC  

E-Print Network (OSTI)

Electronic structure of the 4d transition metal carbides: Dispersed fluorescence spectroscopy of Mo transition metal carbides is also provided. © 2001 American Institute of Physics. DOI: 10.1063/1.1316042 I, and astrochemistry. Within the 4d se- ries, the diatomic transition metal carbides have aroused considerable interest

Morse, Michael D.

353

Constraints on (Omega_m,Omega_Lambda) using distributions of inclination angles for high redshift filaments  

E-Print Network (OSTI)

In this paper we present a scale free method to determine the cosmological parameters (Omega_m, Omega_Lambda). The method is based on the requirement of isotropy of the distribution of orientations of cosmological filaments. The current structure formation paradigm predicts that the first structures to form are voids and filaments, causing a web-like structure of the matter distribution at high redshifts. Recent observational evidence suggests that the threads, or filaments, of the cosmic web most easily are mapped in Ly-alpha emission. We describe how such a 3D map can be used to constrain the cosmological parameters in a way which, contrary to most other cosmological tests, does not require the use of a standard rod or a standard candle. We perform detailed simulations in order to define the optimal survey parameters for the definition of an observing programme aimed to address this test, and to investigate how statistical and observational errors will influence the results. We conclude that observations should target filaments of comoving size 15-50 Mpc in the redshift range 2-4, and that each filament must be defined by at least four Ly-alpha emitters. Detection of 20 filaments will be sufficient to obtain a result, while 50 filaments will make it possible to place significant new constraints on the values of Omega_m and Omega_Lambda permitted by the current supernova observations. In a future paper we study how robust these conclusions are to systematic velocities in the survey box.

M. Weidinger; P. Moller; J. P. U. Fynbo; B. Thomsen; M. P. Egholm

2002-05-24T23:59:59.000Z

354

Influence of interface compounds on interface bonding characteristics of aluminium and silicon carbide  

SciTech Connect

The interface plays an important role in improving the mechanical properties of metal matrix composites. Hence, it is essential to evaluate interface bonding of Aluminium/Silicon carbide. The interface bonding of Aluminum/Silicon carbide samples were prepared by various processing temperatures at constant holding time. The interface compounds at the interface were evaluated by an energy dispersive spectroscope and diffusion length of compounds was calculated by Arrhenius equation. The interface structure was analyzed by a scanning electron microscope. The interface characteristics were evaluated by tensile test and microhardness test.

Sozhamannan, G.G., E-mail: sozhan30@yahoo.co.in [Department of Mechanical Engineering, College of Engineering, Anna University Chennai, Chennai-600025 (India); Prabu, S. Balasivanandha [Department of Mechanical Engineering, College of Engineering, Anna University Chennai, Chennai-600025 (India)

2009-09-15T23:59:59.000Z

355

Design and Testing of a Boron Carbide Capsule for Spectral Tailoring in Mixed-Spectrum Reactors  

SciTech Connect

A boron carbide capsule has been designed and used for spectral-tailoring experiments at the TRIGA reactor at Washington State University. Irradiations were conducted in pulsed mode and in continuous operation for up to 4 hours. A cadmium cover was used to reduce thermal heating. The neutron spectrum calculated with MCNP was found to be in good agreement with reactor dosimetry measurements using the STAY'SL computer code. The neutron spectrum resembles that of a fast reactor. Design of a capsule using boron carbide enriched in {sup 10}B shows that it is possible to produce a neutron spectrum similar to {sup 235}U fission.

Greenwood, Lawrence R.; Wittman, Richard S.; Pierson, Bruce D.; Metz, Lori A.; Payne, Rosara F.; Finn, Erin C.; Friese, Judah I.

2012-03-01T23:59:59.000Z

356

Cyanophycin Mediates the Accumulation and Storage of Fixed Carbon in Non-Heterocystous Filamentous Cyanobacteria from Coniform Mats  

E-Print Network (OSTI)

Thin, filamentous, non-heterocystous, benthic cyanobacteria (Subsection III) from some marine, lacustrine and thermal environments aggregate into macroscopic cones and conical stromatolites. We investigate the uptake and ...

Liang, Biqing

357

THE SPIN AND ORIENTATION OF DARK MATTER HALOS WITHIN COSMIC FILAMENTS  

SciTech Connect

Clusters, filaments, sheets, and voids are the building blocks of the cosmic web. Forming dark matter halos respond to these different large-scale environments, and this in turn affects the properties of galaxies hosted by the halos. It is therefore important to understand the systematic correlations of halo properties with the morphology of the cosmic web, as this informs both about galaxy formation physics and possible systematics of weak lensing studies. In this study, we present and compare two distinct algorithms for finding cosmic filaments and sheets, a task which is far less well established than the identification of dark matter halos or voids. One method is based on the smoothed dark matter density field and the other uses the halo distributions directly. We apply both techniques to one high-resolution N-body simulation and reconstruct the filamentary/sheet like network of the dark matter density field. We focus on investigating the properties of the dark matter halos inside these structures, in particular, on the directions of their spins and the orientation of their shapes with respect to the directions of the filaments and sheets. We find that both the spin and the major axes of filament halos with masses approx<10{sup 13} h {sup -1} M{sub sun} are preferentially aligned with the direction of the filaments. The spins and major axes of halos in sheets tend to lie parallel to the sheets. There is an opposite mass dependence of the alignment strength for the spin (negative) and major (positive) axes, i.e. with increasing halo mass the major axis tends to be more strongly aligned with the direction of the filament, whereas the alignment between halo spin and filament becomes weaker with increasing halo mass. The alignment strength as a function of the distance to the most massive node halo indicates that there is a transit large-scale environment impact: from the two-dimensional collapse phase of the filament to the three-dimensional collapse phase of the cluster/node halo at small separation. Overall, the two algorithms for filament/sheet identification investigated here agree well with each other. The method based on halos alone can be easily adapted for use with observational data sets.

Zhang Youcai; Yang Xiaohu; Lin Weipeng [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Partner Group of MPA, Nandan Road 80, Shanghai 200030 (China); Faltenbacher, Andreas; Springel, Volker [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Strasse 1, 85748 Garching (Germany); Wang Huiyuan, E-mail: yczhang@shao.ac.c [Key Laboratory for Research in Galaxies and Cosmology, Center for Astrophysics, University of Science and Technology of China, 230026 (China)

2009-11-20T23:59:59.000Z

358

Filament-strung stand-off elements for maintaining pane separation in vacuum insulating glazing units  

DOE Patents (OSTI)

A vacuum insulating glazing unit (VIGU) comprises first and second panes of transparent material, first and second anchors, a plurality of filaments, a plurality of stand-off elements, and seals. The first and second panes of transparent material have edges and inner and outer faces, are disposed with their inner faces substantially opposing one another, and are separated by a gap having a predetermined height. The first and second anchors are disposed at opposite edges of one pane of the VIGU. Each filament is attached at one end to the first anchor and at the other end to the second anchor, and the filaments are collectively disposed between the panes substantially parallel to one another. The stand-off elements are affixed to each filament at predetermined positions along the filament, and have a height substantially equal to the predetermined height of the gap such that the each stand-off element touches the inner surfaces of both panes. The seals are disposed about the edges of the panes, enclosing the stand-off elements within a volume between the panes from which the atmosphere may be evacuated to form a partial vacuum.

Bettger, Kenneth J; Stark, David H

2013-08-20T23:59:59.000Z

359

An Excursion Set Model of the Cosmic Web: The Abundance of Sheets, Filaments, and Halos  

Science Journals Connector (OSTI)

We discuss an analytic approach for modeling structure formation in sheets, filaments, and knots. This is accomplished by combining models of triaxial collapse with the excursion set approach: sheets are defined as objects that have collapsed along only one axis, filaments have collapsed along two axes, and halos are objects in which triaxial collapse is complete. In the simplest version of this approach, which we develop here, large-scale structure shows a clear hierarchy of morphologies: the mass in large-scale sheets is partitioned up among lower mass filaments, which themselves are made up of still lower mass halos. Our approach provides analytic estimates of the mass fraction in sheets, filaments, and halos and its evolution, for any background cosmological model and any initial fluctuation spectrum. In the currently popular ?CDM model, our analysis suggests that more than 99% of the cosmic mass is in sheets, and 72% in filaments, with mass larger than 1010M? at the present time. For halos, this number is only 46%. Our approach also provides analytic estimates of how halo abundances at any given time correlate with the morphology of the surrounding large-scale structure and how halo evolution correlates with the morphology of large-scale structure.

Jiajian Shen; Tom Abel; H. J. Mo; Ravi K. Sheth

2006-01-01T23:59:59.000Z

360

An Excursion Set Model of the Cosmic Web: the Abundance of Sheets, Filaments And Halos  

SciTech Connect

We discuss an analytic approach for modeling structure formation in sheets, filaments and knots. This is accomplished by combining models of triaxial collapse with the excursion set approach: sheets are defined as objects which have collapsed along only one axis, filaments have collapsed along two axes, and halos are objects in which triaxial collapse is complete. In the simplest version of this approach, which we develop here, large scale structure shows a clear hierarchy of morphologies: the mass in large-scale sheets is partitioned up among lower mass filaments, which themselves are made-up of still lower mass halos. Our approach provides analytic estimates of the mass fraction in sheets, filaments and halos, and its evolution, for any background cosmological model and any initial fluctuation spectrum. In the currently popular {Lambda}CDM model, our analysis suggests that more than 99% of the mass in sheets, and 72% of the mass in filaments, is stored in objects more massive than 10{sup 10}M{sub {circle_dot}} at the present time. For halos, this number is only 46%. Our approach also provides analytic estimates of how halo abundances at any given time correlate with the morphology of the surrounding large-scale structure, and how halo evolution correlates with the morphology of large scale structure.

Shen, Jiajian; /Penn State U., Astron. Astrophys.; Abel, Tom; /KIPAC, Menlo Park; Mo, Houjun; /Massachusetts U., Amherst; Sheth, Ravi; /Pennsylvania U.

2006-01-11T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Diffusion and impurity segregation in hydrogen-implanted silicon carbide  

SciTech Connect

Diffusion and segregation behavior of hydrogen and oxygen in silicon carbide subjected to H implantation and subsequent annealing were studied with a number of analytical techniques including Secondary Ion Mass Spectrometry (SIMS), Rutherford backscattering spectrometry in channeling geometry, field emission scanning electron microscopy, optical microscopy, cross-sectional transmission electron microscopy, and atomic force microscopy. H{sup +} implantation was carried out with energies of 200?keV, 500?keV, or 1?MeV to doses of 1??10{sup 16}, 1??10{sup 17}, or 2??10{sup 17} ion/cm{sup 2}, and thermal treatment was conducted in flowing argon for 1 to 2 h at temperatures of 740, 780, 1000, or 1100?C. The process of migration and eventual loss of hydrogen in a point defect regime is postulated to proceed to a large extent through ionized vacancies. This conclusion was derived from the observed substantial difference in H mobilities in n- vs. p-type SiC as the population of ionized vacancies is governed by the Fermi-Dirac statistics, i.e., the position of the Fermi level. For higher doses, a well defined buried planar zone forms in SiC at the maximum of deposited energy, comprising numerous microvoids and platelets that are trapping sites for hydrogen atoms. At a certain temperature, a more or less complete exfoliation of the implanted layer is observed. For a 1?MeV implant heated to 1100?C in nominally pure argon, SIMS profiling reveals a considerable oxygen peak of 10{sup 16} O atoms/cm{sup 2} situated at a depth close to that of the peak of the implanted H{sup +}. Similarly, 1100?C annealing of a 200?keV implant induces the formation of a thin oxide (4?nm), located at the interface between the implanted layer and the substrate as evidenced by both SIMS and HRTEM. The measurements were taken on the part of the sample that remained un-exfoliated. In view of a lack of convincing evidence that a hexagonal SiC might contain substantial amounts of oxygen, further investigation is under way to elucidate its presence in the irradiation-damaged films.

Barcz, A., E-mail: barcz@ite.waw.pl [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Kozubal, M.; Ratajczak, J.; Go?aszewska, K. [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Jakie?a, R.; Dyczewski, J.; Wojciechowski, T. [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Celler, G. K. [Institute for Advanced Materials, Devices, and Nanotechnology (IAMDN)/Department of Materials Science and Engineering, Rutgers University, New Brunswick, New Jersey 08901 (United States)

2014-06-14T23:59:59.000Z

362

2.04 - Processing of Silicon Carbide-Based Ceramics  

Science Journals Connector (OSTI)

Abstract The history of the success of the covalently bonded compound silicon carbide (SiC) started more than a century ago (1893) with the synthesis of raw SiC by Edward Goodrich Acheson. Though even today Acheson's process is still current, other synthesis methods have also been developed for the production of SiC powders, whiskers, platelets, and fibers. Due to its low chemical reactivity, it turned out to be difficult to develop methods and processes for the production of SiC-based ceramics. In the past, many approaches for processing SiC have been attempted with specific benefits and limitations in each case. Today a large spectrum of SiC-based ceramics manufactured by a wide variety of processing techniques exists. In order to get a systematic overview over the complex set of SiC-based ceramics, they can be divided into three groups. The first group includes porous ceramics with relatively coarse SiC particles bonded in a matrix of amorphous aluminum silicate. These SiC-based ceramics may be compared with the well-known traditional silicate ceramics in terms of processing technique via sintering in air and corresponding microstructure evolution. Some grinding tools, refractory bricks and foam filters belong to this silicate bonded SiC-based ceramics. The second group is sintered as well, but the focus of attention is more sharply directed toward keeping the intrinsic characteristics of SiC as a polycrystalline ceramic material. Typically they are sintered in protective atmospheres utilizing solid-state, liquid-phase or vapor-phase (evaporation-condensation) mechanisms. However, some of the desired properties can sometimes only be achieved by using pressure-assisted sintering techniques such as axial hot pressing, hot isostatic pressing or field-assisted sintering. This group of sintered SiC-based ceramics also contains some advanced modifications such as in situ toughened or nanostructured ceramics. The third group uses three reaction bonding processes for consolidation, namely liquid-solid, gas phase, and polymer-derived reaction bonding, in order to reduce the maximum consolidation temperature and to increase densification with the aim to achieve low-to-zero shrinkage. All reaction bonding approaches result in untoughened SiC ceramics like nitride bonded, chemical vapor infiltrated silicon, carbon bonded, and ex situ toughened ceramic matrix composites (i.e. carbon and SiC fiber-reinforced ceramics). Through reaction bonding, paper and even natural products like wood can be converted into SiC-based ceramics.

Jochen Kriegesmann

2014-01-01T23:59:59.000Z

363

Transport study of hafnium(IV) and zirconium(IV) ions mutual separation by using Tri-n-butyl phosphate-xylene-based supported liquid membranes  

SciTech Connect

A Hf transport study through supported liquid membranes has been carried out to determine flux and permeability data for this metal ion. Tri-n-butyl phosphate (TBP)-xylene-based liquid membranes supported in polypropylene hydrophobic microporous film have been used. These data for hafnium and the previous data for zirconium have furnished the Zr to Hf flux ratio (S) as a function of nitric acid and TBP concentrations of the order of 12 in a single stage at room temperature. Optimum conditions for the separation of these two metal ions appear to 5-6 TBP mol/dm{sup 3} HNO{sub 3}, concentrations {le} 2.93 mol/dm{sup 3}, and 10C. The value of S from an aqueous solution containing 2.4% Hf with respect to Zr has been found to be >125 at 10C and 1.78 mol/dm{sup 3} TBP concentration in the membrane. The technique appears to be feasible for purification of Zr respect to Hf or vice versa.

Chaudry, M.A.; Ahmed, B. (Pakistan Inst. of Nuclear Science and Technology, Islamabad (Pakistan))

1992-02-01T23:59:59.000Z

364

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

SciTech Connect

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.

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

365

Genetic Regulation of Differentiated Microbial Filaments | U.S. DOE Office  

Office of Science (SC) Website

Genetic Regulation of Differentiated Microbial Filaments Genetic Regulation of Differentiated Microbial Filaments Biological and Environmental Research (BER) BER Home About Research Facilities Science Highlights Searchable Archive of BER Highlights External link Benefits of BER Funding Opportunities Biological & Environmental Research Advisory Committee (BERAC) News & Resources Contact Information Biological and Environmental Research U.S. Department of Energy SC-23/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3251 F: (301) 903-5051 E: sc.ber@science.doe.gov More Information » September 2012 Genetic Regulation of Differentiated Microbial Filaments Discovering how a microbe makes complex structures to perform complex functions. Print Text Size: A A A Subscribe FeedbackShare Page

366

Generation of long-lived underdense channels using femtosecond filamentation in air  

E-Print Network (OSTI)

Using femtosecond laser pulses at 800 and 400 nm, we characterize the formation of underdense channels in air generated by laser filamentation at the millijoule-energy level by means of transverse interferometry. We find that using tight focusing conditions, filamentation generates a supersonic shock wave and that the resulting low-density channel lasts for more than 90 ms. Comparison of these results with hydrodynamic simulations using an Eulerian hydrodynamic code gives an good agreement and allows us to estimate the initial gas temperature at $\\sim1000$ K. The influence of experimental parameters such as the focusing conditions for the ultrashort laser pulse, its polarization or the wavelength used is then studied and linked to previous characterizations of filamentation-generated plasma columns.

Point, Guillaume; Couairon, Arnaud; Mysyrowicz, Andr; Houard, Aurlien

2014-01-01T23:59:59.000Z

367

Catalytic hydrodenitrogenation of indole over molybdenum nitride and carbides with different structures  

E-Print Network (OSTI)

-derived feedstocks, is one of the hydropuri®- cation processes in the oil re®nery industry. These hydrotreating as commercial hydrotreating catalysts for more than 40 years. In recent years, however, these catalysts and carbides are superior to or compar- able to commercial hydrotreating catalysts. Recently Suslick et al. [11

Suslick, Kenneth S.

368

On the development of ice-templated silicon carbide scaffolds for nature-inspired structural materials  

E-Print Network (OSTI)

received most interest as a means to produce porous scaffolds by using ice as a template for complexOn the development of ice-templated silicon carbide scaffolds for nature-inspired structural of ceramic scaffolds using the ice-templating, or freeze casting, technique provides a relatively simple

Ritchie, Robert

369

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

SciTech Connect

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.

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

370

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

SciTech Connect

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 processingstructureproperties relationships facilitates tuning of the carbon material to the requirements of a certain application.

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

2011-01-01T23:59:59.000Z

371

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

E-Print Network (OSTI)

June 2014 Keywords: Low-temperature combustion syn- thesis Tungsten carbide Electrocatalyst Gas burning on the environment, and reduce dependence on fossil fuels, development of pure electric and fuel of highly efficient low-cost electrode catalysts for the oxygen reduction cathode, metaleair batteries have

Volinsky, Alex A.

372

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

E-Print Network (OSTI)

monitoring, solid-oxide fuel cells, and coal gasification, require operation at much higher temperatures thanSulfur surface chemistry on the platinum gate of a silicon carbide based hydrogen sensor Yung Ho to hydrogen sulfide, even in the presence of hydrogen or oxygen at partial pressures of 20­600 times greater

Tobin, Roger G.

373

Mechanical properties of WC10Co cemented carbides sintered from nanocrystalline spray conversion processed powders  

E-Print Network (OSTI)

Mechanical properties of WC±10Co cemented carbides sintered from nanocrystalline spray conversion as the spray conversion process [2]. The WC particle sizes in powders fabricated by the spray conversion: microstructural parameters such as WC grain size, Co mean free path and WC/WC contiguity; chemical factors

Hong, Soon Hyung

374

Characterizations of WC-10Co nanocomposite powders and subsequently sinterhip sintered cemented carbide  

SciTech Connect

Ultrafine WC-Co cemented carbides, combining high hardness and high toughness, are expected to find broad applications. In this study, WC-10Co-0.4VC-0.4Cr{sub 3}C{sub 2} (wt.%) nanocomposite powders, whose average grain size was about 30 nm, were fabricated by spray pyrolysis-continuous reduction and carbonization technology. The as-prepared nanocomposite powders were characterized and analyzed by chemical methods, scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET analysis and atomic force microscopy (AFM). Furthermore, 'sinterhip' was used in the sintering process, by which ultrafine WC-10Co cemented carbides with an average grain size of 240 nm were prepared. The material exhibited high Rockwell A hardness of HRA 92.8, Vickers hardness HV{sub 1} 1918, and transverse rapture strength (TRS) of 3780 MPa. The homogeneously dispersed grain growth inhibitors such as VC, Cr{sub 3}C{sub 2} in nanocomposite powder and the special nonmetal-metal nanocomposite structure of WC-10Co nanocomposite powder played very important roles in obtaining ultrafine WC-10Co cemented carbide with the desired properties and microstructure. There was an abundance of triple junctions in the ultrafine WC-10Co cemented carbide; these triple junctions endowed the sintered specimen with high mechanical properties.

Shi, X.L. [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122Luoshi Road, Wuhan 430070 (China)]. E-mail: sxl071932@126.com; Shao, G.Q. [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122Luoshi Road, Wuhan 430070 (China); Duan, X.L. [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122Luoshi Road, Wuhan 430070 (China); Xiong, Z. [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122Luoshi Road, Wuhan 430070 (China); Yang, H. [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122Luoshi Road, Wuhan 430070 (China)

2006-12-15T23:59:59.000Z

375

Structure and chemistry of a metal cluster with a four-coordinate carbide carbon atom  

SciTech Connect

Molecular metal clusters with carbide carbon atoms of low coordination number have been prepared; they are the anionic (HFe/sub 4/C(CO)/sub 12//sup -/) and (Fe/sub 4/C(CO)/sub 12//sup 2 -/) clusters. An x-ray crystallographic analysis of a tetraaminozinc salt of the latter has established a butterfly array of iron atoms with the carbide carbon atom centered above the wings of the Fe/sub 4/ core. Each iron atom was bonded to three peripheral carbonyl ligands. The distances from the carbide carbon to iron were relatively short, particularly those to the apical iron atoms (1.80 A average). Protonation of the anionic carbide clusters reversibly yielded HFe/sub 4/(CH)(CO)/sub 12/, and methylation of the dianion gave (Fe/sub 4/(CC(O)CH/sub 3/)(CO)/sub 12//sup -/). Oxidation of (Fe/sub 4/C(CO)/sub 12//sup 2 -/) yielded the coordinately unsaturated Fe/sub 4/C(CO)/sub 12/ cluster, which was extremely reactive. Hydrogen addition to this iron cluster was rapid below 0/sup 0/C, and a C-H bond was formed in this transformation.

Davis, J.H. (Argonne National Lab., IL); Beno, M.A.; Williams, J.M.; Zimmie, J.A.; Tachikawa, M.; Muetterties, E.L.

1981-02-01T23:59:59.000Z

376

Thin Film Solid-State Reactions Forming Carbides as Contact Materials for Carbon-Containing Semiconductors  

SciTech Connect

Metal carbides are good candidates to contact carbon-based semiconductors (SiC, diamond, and carbon nanotubes). Here, we report on an in situ study of carbide formation during the solid-state reaction between thin films. The solid-state reaction was examined between 11 transition metals (W, Mo, Fe, Cr, V, Nb, Mn, Ti, Ta, Zr, and Hf) and an amorphous carbon layer. Capping layers (C or TiN) of different thicknesses were applied to prevent oxidation. Carbide formation is evidenced for nine metals and the phases formed have been identified (for a temperature ranging from 100 to 1100 C). W first forms W{sub 2}C and then WC; Mo forms Mo{sub 2}C; Fe forms Fe{sub 3}C; Cr first forms metastable phases Cr{sub 2}C and Cr{sub 3}C{sub 2-x}, and finally forms Cr{sub 3}C{sub 2}; V forms VC{sub x}; Nb transforms into Nb{sub 2}C followed by NbC; Ti forms TiC; Ta first forms Ta{sub 2}C and then TaC; and Hf transforms into HfC. The activation energy for the formation of the various carbide phases has been obtained by in situ x-ray diffraction.

Leroy,W.; Detavernier, C.; Van Meirhaeghe, R.; Lavoie, C.

2007-01-01T23:59:59.000Z

377

Ternary rare earth and actinoid transition metal carbides viewed as carbometalates  

SciTech Connect

Ternary carbides A{sub x}T{sub y}C{sub z} (A=rare earth metals and actinoids; T=transition metals) with monoatomic species C{sup 4-} as structural entities are classified according to the criteria (i) metal to carbon ratio, (ii) coordination number of the transition metal by carbon atoms, and (iii) the dimensionality of the anionic network [T{sub y}C{sub z}]{sup n-}. Two groups are clearly distinguishable, depending on the metal to carbon ratio. Those where this ratio is equal to or smaller than 2 may be viewed as carbometalates, thus extending the sequence of complex anions from fluoro-, oxo-, and nitridometalates to carbometalates. The second group, metal-rich carbides with metal to carbon ratios equal to or larger than 4 is better viewed as typical intermetallics (''interstitial carbides''). The chemical bonding properties have been investigated by analyzing the Crystal Orbital Hamilton Population (COHP). The chemical bonding situation with respect to individual T-C bonds is similar in both classes. The main difference is the larger number of metal-metal bonds in the crystal structures of the metal-rich carbides.

Dashjav, Enkhtsetseg [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany); Kreiner, Guido [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany); Schnelle, Walter [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany); Wagner, Frank R. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany); Kniep, Ruediger [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Strasse 40, D-01187 Dresden (Germany)], E-mail: Kniep@cpfs.mpg.de; Jeitschko, Wolfgang [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Wilhelm-Klemm-Strasse 8, D-48149 Muenster (Germany)], E-mail: jeitsch@uni-muenster.de

2007-02-15T23:59:59.000Z

378

FROM DUSTY FILAMENTS TO MASSIVE STARS: THE CASE OF NGC 7538 S  

SciTech Connect

We report on high-sensitivity and high angular resolution archival Submillimeter Array observations of the large ({approx}15,000 AU) putative circumstellar disk associated with the O-type protostar NGC 7538 S. Observations of the continuum resolve this putative circumstellar disk into five compact sources, with sizes {approx}3000 AU and masses {approx}10 M{sub Sun }. This confirms the results of recent millimeter observations made with CARMA/BIMA toward this object. However, we find that most of these compact sources eject collimated bipolar outflows, revealed by our silicon monoxide (SiO J = 5-4) observations, and confirm that these sources have a (proto)stellar nature. All outflows are perpendicular to the large and rotating dusty structure. We propose therefore that, rather than being a single massive circumstellar disk, NGC 7538 S could instead be a large and massive contracting or rotating filament that is fragmenting at scales of 0.1-0.01 pc to form several B-type stars, via the standard process involving outflows and disks. As in recent high spatial resolution studies of dusty filaments, our observations also suggest that thermal pressure does not seem to be sufficient to support the filament, so that either additional support needs to be invoked or else the filament must be in the process of collapsing. A smoothed particle hydrodynamics numerical simulation of the formation of a molecular cloud by converging warm neutral medium flows produces contracting filaments whose dimensions and spacings between the stars forming within them, as well as their column densities, strongly resemble those observed in the filament reported here.

Naranjo-Romero, Raul; Zapata, Luis A.; Vazquez-Semadeni, Enrique [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Morelia 58090 (Mexico); Takahashi, Satoko [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Palau, Aina [Institut de Ciencies de l'Espai (CSIC-IEEC), Campus UAB-Facultat de Ciencies, Torre C5-parell 2, E-08193 Bellaterra (Spain); Schilke, Peter [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany)

2012-09-20T23:59:59.000Z

379

Stabilization of the filamentation instability and the anisotropy of the background plasma  

SciTech Connect

The interaction of a relativistic electron beam with an anisotropic Maxwellian plasma is investigated, with a focus on the stabilization condition for the filamentation instability. It is found that this condition is very sensitive to the anisotropy degree of the background plasma so that the investigation of the beam instability may not be easily decoupled from the state of the background plasma in typical fusion conditions. Furthermore, regardless of the plasma isotropy, filamentation can no longer be suppressed when the beam density exceeds a threshold value that is determined.

Bret, A.; Deutsch, C. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Laboratoire de Physique des Gaz et des Plasmas (CNRS-UMR 8578), Universite Paris XI, Batiment 210, 91405 Orsay cedex (France)

2006-02-15T23:59:59.000Z

380

Robustness of the filamentation instability for asymmetric plasma shells collision in arbitrarily oriented magnetic field  

SciTech Connect

The filamentation instability triggered when two counter streaming plasma shells overlap appears to be the main mechanism by which collisionless shocks are generated. It has been known for long that a flow aligned magnetic field can completely suppress this instability. In a recent paper [Phys. Plasmas 18, 080706 (2011)], it was demonstrated in two dimensions that for the case of two cold, symmetric, relativistically colliding shells, such cancellation cannot occur if the field is not perfectly aligned. Here, this result is extended to the case of two asymmetric shells. The filamentation instability appears therefore as an increasingly robust mechanism to generate shocks.

Bret, A. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain and Instituto de Investigaciones Energticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain)] [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain and Instituto de Investigaciones Energticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain)

2013-10-15T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Observations of the filamentation of high-intensity laser-produced electron beams  

SciTech Connect

Filamented electron beams have been observed to be emitted from the rear of thin solid targets irradiated by a high-intensity short-pulse laser when there is low-density plasma present at the back of the target. These observations are consistent with a laser-generated beam of relativistic electrons propagating through the target, which is subsequently fragmented by a Weibel-like instability in the low-density plasma at the rear. These measurements are in agreement with particle-in-cell simulations and theory, since the filamentation instability is predicted to be dramatically enhanced when the electron beam density approaches that of the background plasma.

Wei, M.S.; Beg, F.N.; Dangor, A.E.; Gopal, A.; Tatarakis, M.; Krushelnick, K. [Blackett Laboratory, Imperial College London SW7 2BZ (United Kingdom); Clark, E.L.; Evans, R.G. [Blackett Laboratory, Imperial College London SW7 2BZ (United Kingdom); Plasma Physics Department, AWE plc, Aldermaston, Reading RG7 4PR (United Kingdom); Ledingham, K.W.D. [Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Plasma Physics Department, AWE plc, Aldermaston, Reading RG7 4PR (United Kingdom); McKenna, P. [Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Norreys, P.A. [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 OQX (United Kingdom); Zepf, M. [Department of Physics, The Queen's University, University Road, Belfast BT7 1NN (United Kingdom)

2004-11-01T23:59:59.000Z

382

StefanBoltzmann law for the tungsten filament of a light bulb: Revisiting the experiment  

Science Journals Connector (OSTI)

A classical laboratory experiment to verify the Stefan-Boltzmann radiation law with the tungsten filaments of commercial incandescent lamps has been fully revisited collecting a fairly large amount of data with a computer-controlled four-channel power supply. In many cases the total power dissipated by the lamp is well described by a sum of two power-law terms with one exponent very close to 4 as predicted by the radiation law and the other very close to 1 as for simple heat conduction. This result was true even for filament surfaces with a shiny metallic appearance whose emissivity should vary with temperature.

2013-01-01T23:59:59.000Z

383

Control filamentous bulking caused by chlorine-resistant Type 021N bacteria through adding a biocide CTAB  

Science Journals Connector (OSTI)

Filamentous bulking sludge due to excessive growth of filamentous bacteria is a serious operational problem in activated sludge plants. The addition of chemicals is one of widespread ways to control filamentous bulking. In this study, filamentous bulking in a continuous activated sludge system was found to be mainly caused by Eikelboom Type 021N filamentous bacteria likely due to low substrate concentration gradients. These Type 021N bacteria were found to be resistant to chlorination, maintaining cell integrity at a dosage of up to 80mgCl/gSS. An alternative biocidal agent, cetyltrimethyl ammonium bromide (CTAB), exhibited a much stronger biocidal effect on these filaments, which significantly improved sludge settleability. Type 021N with filamentous index of 5 was selectively killed, but floc-formers recovery their activity after CTAB termination. The study implied that CTAB might have more penetration capacity to cell wall of chlorine-resistant Type 021N bacteria. We therefore suggest the penetration property of filament cell wall should be considered or tested before the selection of biocide type in practice.

Jianhua Guo; Yongzhen Peng; Zhongwei Wang; Zhiguo Yuan; Xiong Yang; Shuying Wang

2012-01-01T23:59:59.000Z

384

Thermo-mechanical Characterization of Metal/Polymer Composite Filaments and Printing Parameter Study for Fused Deposition Modeling in the 3D Printing Process  

Science Journals Connector (OSTI)

New metal/polymer composite filaments for fused deposition modeling (FDM) processes were developed in order to observe the thermo-mechanical properties of the new filaments. The acrylonitrile butadiene styrene (A...

Seyeon Hwang; Edgar I. Reyes; Kyoung-sik Moon

2014-10-01T23:59:59.000Z

385

DOI: 10.1002/cphc.200900615 From Branched Networks of Actin Filaments to Bundles  

E-Print Network (OSTI)

DOI: 10.1002/cphc.200900615 From Branched Networks of Actin Filaments to Bundles Yifat Brill- ses. Cell movement is driven by the dynamic growth of polar actin networks of various structures,[1 containing the lamellipodium, but lacking the nucleus, micro- tubules and other organels can perform movement

Ben-Shaul, Avinoam

386

FILAMENTOUS FLOWER Controls the Formation and Development of Arabidopsis Inflorescences and Floral Meristems  

Science Journals Connector (OSTI)

...leafy (lf y), and unusual floral organs (ufo), filamentous structures are formed...CAULIFLOWER (CAL), UNUSUAL FLORAL ORGANS (UFO), two flowering-time loci (FT and FWA...meristem identity genes, AP1, FIL, CAL, UFO, FT, and FWA, and analyzed structural...

Shinichiro Sawa; Toshiro Ito; Yoshiro Shimura; Kiyotaka Okada

387

Fossil evidence for spin alignment of Sloan Digital Sky Survey galaxies in filaments  

Science Journals Connector (OSTI)

......and so we briefly review what has been achieved using other, more standard, methods. We also review the theoretical motivation...identification. We plan to use the edge-on...these filaments. The plan of the paper is to review the theoretical notions......

Bernard J. T. Jones; Rien van de Weygaert; Miguel A. Aragn-Calvo

2010-10-21T23:59:59.000Z

388

Role of ATP-Hydrolysis in the Dynamics of a Single Actin Filament Padinhateeri Ranjith,  

E-Print Network (OSTI)

Role of ATP-Hydrolysis in the Dynamics of a Single Actin Filament Padinhateeri Ranjith, * Kirone, and ATP hydrolysis of subunits either according to the vectorial mechanism or to the random mechanism and by comparing two possible mechanisms of ATP hydro- lysis. Our emphasis is mainly on two possible limiting

Lacoste, David

389

Heat transfer in sunspot penumbrae. Origin of dark-cored penumbral filaments  

E-Print Network (OSTI)

Context: Observations at 0.1" have revealed the existence of dark cores in the bright filaments of sunspot penumbrae. Expectations are high that such dark-cored filaments are the basic building blocks of the penumbra, but their nature remains unknown. Aims: We investigate the origin of dark cores in penumbral filaments and the surplus brightness of the penumbra. To that end we use an uncombed penumbral model. Methods: The 2D stationary heat transfer equation is solved in a stratified atmosphere consisting of nearly horizontal magnetic flux tubes embedded in a stronger and more vertical field. The tubes carry an Evershed flow of hot plasma. Results: This model produces bright filaments with dark cores as a consequence of the higher density of the plasma inside the tubes, which shifts the surface of optical depth unity toward higher (cooler) layers. Our calculations suggest that the surplus brightness of the penumbra is a natural consequence of the Evershed flow, and that magnetic flux tubes about 250 km in diameter can explain the morphology of sunspot penumbrae.

B. Ruiz Cobo; L. R. Bellot Rubio

2008-10-07T23:59:59.000Z

390

Coiled-coil intermediate filament stutter instability and molecular unfolding Melis Arslana  

E-Print Network (OSTI)

Coiled-coil intermediate filament stutter instability and molecular unfolding Melis Arslana , Zhao of the discontinuities in the dimer's coiled-coil region is the so-called `stutter' region. The stutter is a region where-tempered metadynamics that for the coil2 domain of vimentin IFs the stutter is more stable in a non

Buehler, Markus J.

391

Eruptions of Two Coupled Filaments Observed by SDO, GONG and STEREO  

E-Print Network (OSTI)

On 2012 July 11, two solar filaments were observed in the northeast of the solar disk and their eruptions due to the interaction between them are studied by using the data from the Solar Dynamics Observatory (SDO), Solar TErrestrial RElations Observatory (STEREO) and Global Oscillation Network Group (GONG). The eastern filament (F1) first erupted toward the northeast. During the eruption of F1, some plasma from F1 fell down and was injected to the North-East part of another filament (F2), and some plasma of F1 fell down to the northern region close to F2 and caused the plasma to brighten. Meanwhile, the North-East part of F2 first started to be active and rise, but did not erupt finally. Then the South-West part of F2 erupted successfully. Therefore, the F2's eruption is a partial filament eruption. Two associated CMEs related to the eruptions were observed by STEREO/COR1. We find two possible reasons that lead to the instability and the eruption of F2. One main reason is that the magnetic loops overlying the...

Xue, Z K; Qu, Z Q; Xu, C L; Zhao, L

2014-01-01T23:59:59.000Z

392

Intermittent Divertor Filaments in the National Spherical Torus Experiment and Their Relation to Midplane Blobs  

SciTech Connect

While intermittent filamentary structures, also known as blobs, are routinely seen in the low-field-side scrape-off layer of the National Spherical Torus Experiment (NSTX) (Ono et al 2000 Nucl. Fusion 40 557), fine structured filaments are also seen on the lower divertor target plates of NSTX. These filaments, not associated with edge localized modes, correspond to the interaction of the turbulent blobs seen near the midplane with the divertor plasma facing components. The fluctuation level of the neutral lithium light observed at the divertor, and the skewness and kurtosis of its probability distribution function, is similar to that of midplane blobs seen in D?; e.g. increasing with increasing radii outside the outer strike point (OSP) (separatrix). In addition, their toroidal and radial movement agrees with the typical movement of midplane blobs. Furthermore, with the appropriate magnetic topology, i.e. mapping between the portion of the target plates being observed into the field of view of the midplane gas puff imaging diagnostic, very good correlation is observed between the blobs and the divertor filaments. The correlation between divertor plate filaments and midplane blobs is lost close to the OSP. This latter observation is consistent with the existence of magnetic shear disconnection due to the lower X-point, as proposed by Cohen and Ryutov (1997 Nucl. Fusion 37 621).

R.J. Maqueda, D.P. Stotler and the NSTX Team.

2010-05-19T23:59:59.000Z

393

Amyloid-Like Adhesins Produced by Floc-Forming and Filamentous Bacteria in Activated Sludge  

Science Journals Connector (OSTI)

...and Filamentous Bacteria in Activated Sludge Published ahead of print on 11 January...importance to the floc properties in activated sludge wastewater treatment plants (WWTP...abundance of amyloid adhesins in activated sludge flocs from different WWTP and the identity...

Poul Larsen; Jeppe Lund Nielsen; Daniel Otzen; Per Halkjr Nielsen

2008-01-11T23:59:59.000Z

394

Self-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons to Fibrils  

E-Print Network (OSTI)

Self-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons, San Francisco, California 94143, United States *S Supporting Information ABSTRACT: Enamel matrix self-assembly tested if amelogenin, the main enamel matrix protein, can self-assemble into ribbon-like structures

Sali, Andrej

395

Plasma density inside a femtosecond laser filament in air: Strong dependence on external focusing  

E-Print Network (OSTI)

Plasma density inside a femtosecond laser filament in air: Strong dependence on external focusing­16 . The plasma generation balances the self-focusing effect and leads to a limited peak intensity 17­19 along, Germany Received 10 March 2006; published 27 September 2006 Our experiment shows that external focusing

Becker, Andreas

396

HINODE OBSERVATIONS OF COHERENT LATERAL MOTION OF PENUMBRAL FILAMENTS DURING AN X-CLASS FLARE  

SciTech Connect

The X-3.4 class flare of 2006 December 13 was observed with a high cadence of 2 minutes at 0.2 arcsec resolution by HINODE/SOT FG instrument. The flare ribbons could be seen in G-band images also. A careful analysis of these observations after proper registration of images shows flare-related changes in penumbral filaments of the associated sunspot for the first time. The observations of sunspot deformation, decay of penumbral area, and changes in magnetic flux during large flares have been reported earlier in the literature. In this Letter, we report lateral motion of the penumbral filaments in a sheared region of the delta-sunspot during the X-class flare. Such shifts have not been seen earlier. The lateral motion occurs in two phases: (1) motion before the flare ribbons move across the penumbral filaments and (2) motion afterward. The former motion is directed away from expanding flare ribbons and lasts for about 4 minutes. The latter motion is directed in the opposite direction and lasts for more than 40 minutes. Further, we locate a patch in adjacent opposite polarity spot moving in opposite direction to the penumbral filaments. Together these patches represent conjugate footpoints on either side of the polarity inversion line, moving toward each other. This converging motion could be interpreted as shrinkage of field lines.

Gosain, S.; Venkatakrishnan, P.; Tiwari, Sanjiv Kumar [Udaipur Solar Observatory, Physical Research Laboratory, P.O. Box 198, Dewali, Badi Road, Udaipur 313001, Rajasthan (India)

2009-12-01T23:59:59.000Z

397

Experimental observation of a traveling plasma grating formed by two crossing filaments in gases  

SciTech Connect

The spatial motion and effective duration of a traveling plasma grating formed by two interfering femtosecond laser filaments in gases is characterized by its Doppler effect imparted on a probe pulse. The shift velocity determined experimentally agrees with the theoretical calculations.

Durand, Magali [Laboratoire d'Optique Appliquee, ENSTA ParisTech-Ecole Polytechnique-CNRS, 91761 Palaiseau (France); ONERA, Chemin de la Huniere, 91761 Palaiseau (France); Liu Yi; Forestier, Benjamin; Houard, Aurelien; Mysyrowicz, Andre [Laboratoire d'Optique Appliquee, ENSTA ParisTech-Ecole Polytechnique-CNRS, 91761 Palaiseau (France)

2011-03-21T23:59:59.000Z

398

Condensation of FtsZ filaments can drive bacterial cell division  

E-Print Network (OSTI)

Condensation of FtsZ filaments can drive bacterial cell division Ganhui Lana , Brian R. Danielsb-ring undergoes a condensation transition from a low- density state to a high-density state and generates the condensation transition, but does not directly generate forces. In vivo fluorescence measurements show that Fts

Sun, Sean

399

Fine Control of THz radiation from filamentation by molecular lensing in air  

E-Print Network (OSTI)

with peak field amplitude as high as 400 kV/cm has been reported with this method using tightly focused with a transmission line model. After the formation of a plasma column by the first filament, which remains for a few to the mutual conductance and inductance, these two parallel plasma columns can be viewed as a transmission line

Paris-Sud XI, Université de

400

Emergent multicellular life cycles in filamentous bacteria owing to density-dependent population dynamics  

Science Journals Connector (OSTI)

...filament lengths is reached. The corresponding pie-charts indicate the fraction of single...In figure-3 f, the box plots and the pie charts show the proportion of short and...capacity. As for the simulation results, the pie charts illustrate three length classes...

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


401

Sec. 2.1 Filaments in the cell 21 PART I -RODS AND ROPES  

E-Print Network (OSTI)

, individual filaments may be relatively straight or highly convoluted, reflecting, in part, their resistance, such as their bending or stretching resistance; the two chapters making up the remainder of Part I consider how, and may themselves be constructed of more elementary chemical units. For example, the monomeric unit

Boal, David

402

Growth, microstructure and electrical properties of sputter-deposited hafnium oxide (HfO2) thin films grown using HfO2 ceramic target  

SciTech Connect

Hafnium oxide (HfO?) thin films have been made by radio-frequency (rf) magnetron-sputtering onto Si(100) substrates under varying growth temperature (Ts). HfO? ceramic target has been employed for sputtering while varying the Ts from room temperature to 500?C during deposition. The effect of Ts on the growth and microstructure of deposited HfO? films has been studied using grazing incidence x-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), and high-resolution scanning electron microscopy (HR-SEM) coupled with energy dispersive x-ray spectrometry (EDS). The results indicate that the effect of Ts is significant on the growth, surface and interface structure, morphology and chemical composition of the HfO? films. Structural characterization indicates that the HfO? films grown at Ts<200 ?C are amorphous while films grown at Ts>200 ?C are nanocrystalline. An amorphous-to-crystalline transition occurs at Ts=200 ?C. Nanocrystalline HfO? films crystallized in a monoclinic structure with a (-111) orientation. XPS measurements indicated the high surface-chemical quality and stoichiometric nature of the grown HfO? films. An interface layer (IL) formation occurs due to reaction at the HfO?-Si interface for HfO? films deposited at Ts>200 ?C. The thickness of IL increases with increasing Ts. XPS and EDS at the HfO?-Si cross-section indicate the IL is a (Hf, Si)-O compound. The electrical characterization using capacitance-voltage measurements indicate that the dielectric constant decreases from 25 to 16 with increasing Ts.

Aguirre, B.; Vemuri, R. S.; Zubia, David; Engelhard, Mark H.; Shutthanandan, V.; Kamala Bharathi, K.; Ramana, Chintalapalle V.

2011-01-01T23:59:59.000Z

403

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

SciTech Connect

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.

Salas, E.; Jimnez Riobo, R. J.; Jimnez-Villacorta, F.; Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientficas, Cantoblanco, 28049 Madrid (Spain)] [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientficas, Cantoblanco, 28049 Madrid (Spain); Snchez-Marcos, J. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientficas, Cantoblanco, 28049 Madrid (Spain) [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientficas, Cantoblanco, 28049 Madrid (Spain); Dept. Qumica-Fsica Aplicada, Universidad Autnoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Muoz-Martn, A.; Prieto, J. E.; Joco, V. [Centro de Microanlisis de Materiales, Universidad Autnoma de Madrid, Cantoblanco, 28049 Madrid (Spain)] [Centro de Microanlisis de Materiales, Universidad Autnoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

2013-12-07T23:59:59.000Z

404

Effect of liquid phase composition on the microstructure and properties of (W,Ti)C cemented carbide cutting tools  

E-Print Network (OSTI)

comprises metal carbides (2­10 vol%), such as VC, ZrC, NbC, TaC, TiC, SiC, Cr3C2, and ThC2; this constituent, which controls the grain size and en- hance the metal carbides formations, is used to decrease the rate of refractory transition metals such as titanium. However, when alloying is attempted, the solid solubili- ties

Hong, Soon Hyung

405

[TiII] and [NiII] emission from the strontium filament of eta Carinae  

E-Print Network (OSTI)

We study the nature of the [TiII] and [NiII] emission from the so-called strontium filament found in the ejecta of eta Carinae. To this purpose we employ multilevel models of the TiII and NiII systems which are used to investigate the physical condition of the filament and the excitation mechanisms of the observed lines. For the TiII ion, for which no atomic data was previously available, we carry out ab initio calculations of radiative transition rates and electron impact excitation rate coefficients. It is found that the observed spectrum is consistent with the lines being excited in a mostly neutral region with an electron density of the order of $10^7$ cm$^{-3}$ and a temperature around 6000 K. In analyzing three observations with different slit orientations recorded between March~2000 and November~2001 we find line ratios that change among various observations, in a way consistent with changes of up to an order of magnitude in the strength of the continuum radiation field. These changes result from different samplings of the extended filament, due to the different slit orientations used for each observation, and yield clues on the spatial extent and optical depth of the filament. The observed emission indicates a large Ti/Ni abundance ratio relative to solar abundances. It is suggested that the observed high Ti/Ni ratio in gas is caused by dust-gas fractionation processes and does not reflect the absolute Ti/Ni ratio in the ejecta of \\etacar. We study the condensation chemistry of Ti, Ni and Fe within the filament and suggest that the observed gas phase overabundance of Ti

M. A. Bautista; H. Hartman; T. R. Gull; N. Smith; K. Lodders

2006-06-12T23:59:59.000Z

406

LINE PROFILES OF CORES WITHIN CLUSTERS. I. THE ANATOMY OF A FILAMENT  

SciTech Connect

Observations are revealing the ubiquity of filamentary structures in molecular clouds. As cores are often embedded in filaments, it is important to understand how line profiles from such systems differ from those of isolated cores. We perform radiative transfer calculations on a hydrodynamic simulation of a molecular cloud in order to model line emission from collapsing cores embedded in filaments. We model two optically thick lines, CS(2-1) and HCN(1-0), and one optically thin line, N{sub 2}H{sup +}(1-0), from three embedded cores. In the hydrodynamic simulation, gas self-gravity, turbulence, and bulk flows create filamentary regions within which cores form. Though the filaments have large dispersions, the N{sub 2}H{sup +}(1-0) lines indicate subsonic velocities within the cores. We find that the observed optically thick line profiles of CS(2-1) and HCN(1-0) vary drastically with viewing angle. In over 50% of viewing angles, there is no sign of a blue asymmetry, an idealized signature of infall motions in an isolated spherical collapsing core. Profiles that primarily trace the cores, with little contribution from the surrounding filament, are characterized by a systematically higher HCN(1-0) peak intensity. The N{sub 2}H{sup +}(1-0) lines do not follow this trend. We demonstrate that red asymmetric profiles are also feasible in the optically thick lines, due to emission from the filament or one-sided accretion flows onto the core. We conclude that embedded cores may frequently undergo collapse without showing a blue asymmetric profile, and that observational surveys including filamentary regions may underestimate the number of collapsing cores if based solely on profile shapes of optically thick lines.

Smith, Rowan J.; Shetty, Rahul; Klessen, Ralf S. [Zentrum fuer Astronomie der Universitaet Heidelberg, Institut fuer Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Stutz, Amelia M., E-mail: rowanjsmith.astro@googlemail.com [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)

2012-05-01T23:59:59.000Z

407

Explicit mean-field radius for nearly parallel vortex filaments in statistical equilibrium  

E-Print Network (OSTI)

Geophysical research has focused on flows, such as ocean currents, as two dimensional. Two dimensional point or blob vortex models have the advantage of having a Hamiltonian, whereas 3D vortex filament or tube systems do not necessarily have one, although they do have action functionals. On the other hand, certain classes of 3D vortex models called nearly parallel vortex filament models do have a Hamiltonian and are more accurate descriptions of geophysical and atmospheric flows than purely 2D models, especially at smaller scales. In these ``quasi-2D'' models we replace 2D point vortices with vortex filaments that are very straight and nearly parallel but have Brownian variations along their lengths due to local self-induction. When very straight, quasi-2D filaments are expected to have virtually the same planar density distributions as 2D models. An open problem is when quasi-2D model statistics behave differently than those of the related 2D system and how this difference is manifested. In this paper we study the nearly parallel vortex filament model of Klein, Majda, Damodaran in statistical equilibrium. We are able to obtain a free-energy functional for the system in a non-extensive thermodynamic limit that is a function of the mean square vortex position $R^2$ and solve \\emph{explicitly} for $R^2$. Such an explicit formula has never been obtained for a non-2D model. We compare the results of our formula to a 2-D formula of \\cite{Lim:2005} and show qualitatively different behavior even when we disallow vortex braiding. We further confirm our results using Path Integral Monte Carlo (Ceperley (1995)) \\emph{without} permutations and that the Klein, Majda, Damodaran model's asymptotic assumptions \\emph{are valid} for parameters where these deviations occur.

Timothy D. Andersen; Chjan C. Lim

2006-11-19T23:59:59.000Z

408

Nonlinear-optical and structural properties of nanocrystalline silicon carbide films  

SciTech Connect

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.

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

409

Fischer-Tropsch Synthesis: Characterization and Reaction Testing of Cobalt Carbide  

SciTech Connect

Hydrogenation of carbon monoxide was investigated for cobalt carbide synthesized from Co{sub 3}O{sub 4} by CO carburization in a fixed-bed reactor. The cobalt carbide synthesized was characterized by BET surface area, X-ray diffraction, scanning electron microscopy, X-ray absorption near edge spectroscopy, and extended X-ray absorption fine structure spectroscopy. The catalysts were tested in the slurry phase using a continuously stirred tank reactor at P = 2.0 MPa, H{sub 2}/CO = 2:1 in the temperature range of 493-523 K, and with space velocities varying from 1 to 3 Nl h{sup -1} g{sub cat}{sup -1}. The results strongly suggest that a fraction of cobalt converts to a form with greater metallic character under the conditions employed. This was more pronounced on a Fischer-Tropsch synthesis run conducted at a higher temperature (523 versus 493 K).

Khalid S.; Mohandas J.C.; Gnanamani M.K.; Jacobs G.; Ma W.; Ji Y.; Davis B.H.

2011-08-15T23:59:59.000Z

410

Gelcasting of CRYSTAR{reg_sign} silicon carbide ceramics. CRADA final report  

SciTech Connect

This Cooperative Research and Development Agreement (CRADA) was undertaken to assess the applicability the gelcasting process for forming ceramic green bodies using Saint-Gobain/Norton Industrial Ceramics Corporation`s proprietary CRYSTAR{reg_sign} silicon carbide powder. A gelcasting process, specifically tailored to Saint-Gobain/Norton`s powder composition, was developed and used successfully to form green bodies for property evaluation. This preliminary evaluation showed that the gelcast material had characteristics and properties comparable to Norton`s baseline material. Wafer carrier molds were received from Norton for gelcasting a complex-shaped configuration with CRYSTAR{reg_sign} silicon carbide. Gelcasting experiments showed that Norton`s standard plaster of paris molds were incompatible with the gelcasting process. Mold surface treatments and the use of alternative castable mold materials were investigated, however, a successful process was not identified. The highest quality parts were cast in either glass or aluminum molds.

Nunn, S.D.; Willkens, C.A.

1998-12-31T23:59:59.000Z

411

Corrosion of silicon carbide hot gas filter candles in gasification environment  

Science Journals Connector (OSTI)

Abstract Reliable cleaning of the fuel gas is required to meet the environmental regulations and to prevent corrosion and erosion of downstream components. The aggressive process environment in biomass-gasification power generation systems or in biofuels production systems can cause corrosion in ceramic hot gas filter candles used to clean the fuel gas. Therefore, to improve the reliability and durability of filters, the influence of steam, ash, and alkaline (earth) metals on the corrosion processes was studied for silicon carbide filter candles fabricated by Pall Schumacher. Exposures with biomass and lignite ashes caused a macroscopically expansion as well as microstructural effects that were analysed by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) spectroscopy. All effects are discussed and it is shown that the employment of silicon carbide filter candles in water vapour containing, alkali-rich gasification environment at high temperature is problematic.

Sarah Schaafhausen; Elena Yazhenskikh; Steffen Heidenreich; Michael Mller

2014-01-01T23:59:59.000Z

412

UNVEILING A NETWORK OF PARALLEL FILAMENTS IN THE INFRARED DARK CLOUD G14.225-0.506  

SciTech Connect

We present the results of combined NH{sub 3} (1,1) and (2,2) line emission observed with the Very Large Array and the Effelsberg 100 m telescope of the infrared dark cloud G14.225-0.506. The NH{sub 3} emission reveals a network of filaments constituting two hub-filament systems. Hubs are associated with gas of rotational temperature T{sub rot} {approx} 15 K, non-thermal velocity dispersion {sigma}{sub NT} {approx} 1 km s{sup -1}, and exhibit signs of star formation, while filaments appear to be more quiescent (T{sub rot} {approx} 11 K and {sigma}{sub NT} {approx} 0.6 km s{sup -1}). Filaments are parallel in projection and distributed mainly along two directions, at P.A. {approx} 10 Degree-Sign and 60 Degree-Sign , and appear to be coherent in velocity. The averaged projected separation between adjacent filaments is between 0.5 pc and 1 pc, and the mean width of filaments is 0.12 pc. Cores within filaments are separated by {approx}0.33 {+-} 0.09 pc, which is consistent with the predicted fragmentation of an isothermal gas cylinder due to the {sup s}ausage{sup -}type instability. The network of parallel filaments observed in G14.225-0.506 is consistent with the gravitational instability of a thin gas layer threaded by magnetic fields. Overall, our data suggest that magnetic fields might play an important role in the alignment of filaments, and polarization measurements in the entire cloud would lend further support to this scenario.

Busquet, Gemma [INAF-Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, I-00133 Roma (Italy); Zhang, Qizhou; Ho, Paul T. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Palau, Aina; Girart, Josep M. [Institut de Ciencies de l'Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre C-5 parell, E-08193 Bellaterra, Catalunya (Spain); Liu, Hauyu Baobab [Academia Sinica Institute of Astronomy and Astrophysics, Taipei, Taiwan (China); Sanchez-Monge, Alvaro [INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-05125 Firenze (Italy); Estalella, Robert [Departament d'Astronomia i Meteorologia, Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona, Catalunya (Spain); De Gregorio-Monsalvo, Itziar [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Pillai, Thushara [Caltech Astronomy Department, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Wyrowski, Friedrich [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Santos, Fabio P.; Franco, Gabriel A. P., E-mail: gemma.busquet@iaps.inaf.it [Departamento de Fisica-ICEx-UFMG, Caixa Postal 702, 30.123-970 Belo Horizonte-MG (Brazil)

2013-02-20T23:59:59.000Z

413

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

E-Print Network (OSTI)

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.

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

2013-11-30T23:59:59.000Z

414

Irradiation creep of nano-powder sintered silicon carbide at low neutron fluences  

SciTech Connect

The irradiation creep behavior of nano-powder sintered silicon carbide was investigated using the bend stress relaxation method under neutron irradiation up to 1.9 dpa. The creep deformation was observed at all temperatures ranging from 380 to 1180 C mainly from the irradiation creep but with the increasing contributions from the thermal creep at higher temperatures. Microstructural observation and data analysis were performed.

Koyanagi, Takaaki [ORNL; Shimoda, Kazuya [Kyoto University, Japan; Kondo, Sosuke [Kyoto University, Japan; Hinoki, Tatsuya [Kyoto University, Japan; Ozawa, Kazumi [ORNL; Katoh, Yutai [ORNL

2014-01-01T23:59:59.000Z

415

Laser-enhanced diffusion of nitrogen and aluminum dopants in silicon carbide  

Science Journals Connector (OSTI)

The diffusivities of different types of dopant atoms in silicon carbide wafers are generally very low. Nd:YAG and excimer lasers have been used to dope silicon carbide with nitrogen and aluminum, respectively. Mathematical models have been presented for the temperature distributions in the wafers to understand the diffusion mechanisms in the laser doping process. Since the silicon carbide substrate reaches its peritectic temperature (3100K) at irradiances of 80.6 and 61MW/cm2 for Nd:YAG and excimer lasers, respectively, lower irradiances were used to achieve solid-state diffusion. The Nd:YAG laser doping process doped nitrogen to a depth of 800nm; the KrF excimer laser doping process produced aluminum dopant depths of 200 and 450nm for different numbers of laser pulses. Two distinct diffusion regions, near-surface and far-surface regions, were identified in the dopant concentration profiles, indicating different diffusion mechanisms in these two regions. The effective diffusion coefficients of nitrogen and aluminum were determined for both regions and found to be 2.4נ10?5 and 9.2נ10?6cm2/s in the near- and far-surface regions for nitrogen, respectively, and 1.2נ10?5 and 1.3נ10?6cm2/s in the near- and far-surface regions for aluminum, respectively. The calculated diffusivities are at least six orders of magnitude higher than the typical values for nitrogen and aluminum, which indicate that the laser doping process enhances significantly the diffusion of dopants in silicon carbide.

Z. Tian; N.R. Quick; A. Kar

2006-01-01T23:59:59.000Z

416

The microstructure and hardness of silicon carbide synthesized by plasma pressure compaction  

Science Journals Connector (OSTI)

Using fine powders of silicon and carbon, silicon carbide was synthesized and compacted using the technique of plasma pressure compaction (P2C). The test samples were obtained by consolidating the powder particles at temperatures of 1400 and 1800C. Microhardness measurements revealed an increase with an increase in temperature of compaction and increased hold time. The conjoint influence of temperature and time of hold at temperature on microstructural development and hardness is presented and discussed.

B.G. Ravi; O.A. Omotoye; T.S. Srivatsan; M. Petrorali; T.S. Sudarshan

2000-01-01T23:59:59.000Z

417

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

DOE Patents (OSTI)

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.

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

1991-02-19T23:59:59.000Z

418

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

DOE Patents (OSTI)

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.

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

1991-01-01T23:59:59.000Z

419

Effect of phosphorus on cleavage fracture in -carbide N. I. Medvedeva,1,2 R. A. Howell,2 D. C. Van Aken,2 and J. E. Medvedeva2  

E-Print Network (OSTI)

Effect of phosphorus on cleavage fracture in -carbide N. I. Medvedeva,1,2 R. A. Howell,2 D. C. Van of the phosphorus effect on ideal cleavage energy and critical stress in -carbide, Fe3AlC, a precipitate the cleavage characteristics of -carbide. We show that strong anisotropy of the Fe-P bonds in Fe3 Al,P C under

Medvedeva, Julia E.

420

Evaluation of Codisposal Viability for TH/U Carbide (Fort Saint Vrain HTGR) DOE-Owned Fuel  

SciTech Connect

There are more than 250 forms of US Department of Energy (DOE)-owned spent nuclear fuel (SNF). Due to the variety of the spent nuclear fuel, the National Spent Nuclear Fuel Program has designated nine representative fuel groups for disposal criticality analyses based on fuel matrix, primary fissile isotope, and enrichment. The Fort Saint Vrain reactor (FSVR) SNF has been designated as the representative fuel for the Th/U carbide fuel group. The FSVR SNF consists of small particles (spheres of the order of 0.5-mm diameter) of thorium carbide or thorium and high-enriched uranium carbide mixture, coated with multiple, thin layers of pyrolytic carbon and silicon carbide, which serve as miniature pressure vessels to contain fission products and the U/Th carbide matrix. The coated particles are bound in a carbonized matrix, which forms fuel rods or ''compacts'' that are loaded into large hexagonal graphite prisms. The graphite prisms (or blocks) are the physical forms that are handled in reactor loading and unloading operations, and which will be loaded into the DOE standardized SNF canisters. The results of the analyses performed will be used to develop waste acceptance criteria. The items that are important to criticality control are identified based on the analysis needs and result sensitivities. Prior to acceptance to fuel from the Th/U carbide fuel group for disposal, the important items for the fuel types that are being considered for disposal under the Th/U carbide fuel group must be demonstrated to satisfy the conditions determined in this report.

H. radulescu

2001-09-28T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Non-equilibrium self-assembly of a filament coupled to ATP/GTP hydrolysis  

E-Print Network (OSTI)

We study the stochastic dynamics of growth and shrinkage of single actin filaments or microtubules taking into account insertion, removal, and ATP/GTP hydrolysis of subunits. The resulting phase diagram contains three different phases: a rapidly growing phase, an intermediate phase and a bound phase. We analyze all these phases, with an emphasis on the bound phase. We also discuss how hydrolysis affects force-velocity curves. The bound phase shows features of dynamic instability, which we characterize in terms of the time needed for the ATP/GTP cap to disappear as well as the time needed for the filament to reach a length of zero, i.e., (to collapse) for the first time. We obtain exact expressions for all these quantities, which we test using Monte Carlo simulations.

Padinhateeri Ranjith; David Lacoste; Kirone Mallick; Jean-Francois Joanny

2008-09-12T23:59:59.000Z

422

Spindles and active vortices in a model of confined filament-motor mixtures  

E-Print Network (OSTI)

Robust self-organization of subcellular structures is a key principle governing the dynamics and evolution of cellular life. In fission yeast cells undergoing division, the mitotic spindle spontaneously emerges from the interaction of microtubules, motor proteins and the confining cell walls, and asters and vortices have been observed to self-assemble in quasi-two dimensional microtubule-kinesin assays. Their is no clear microscopic picture of the role of the active motors driving this pattern formation, and the relevance of continuum modeling to filament-scale structures remains uncertain. Here we present results of numerical simulations of a discrete filament-motor protein model confined to a pressurised cylindrical box. Stable spindles, nematic configurations, asters and high-density semi-asters spontaneously emerge, the latter pair having also been observed in cytosol confined within emulsion droplets. State diagrams are presented delineating each stationary state as the pressure, motor speed and motor de...

Head, David A; Gompper, Gerhard

2011-01-01T23:59:59.000Z

423

Sensitivity of propagation and energy deposition in femtosecond filamentation to the nonlinear refractive index  

E-Print Network (OSTI)

The axial dependence of femtosecond filamentation in air is measured under conditions of varying laser pulsewidth, energy, and focusing f-number. Filaments are characterized by the ultrafast z-dependent absorption of energy from the laser pulse and diagnosed by measuring the local single cycle acoustic wave generated. Results are compared to 2D+1 simulations of pulse propagation, whose results are highly sensitive to the instantaneous (electronic) part of the nonlinear response of $N_2$ and $O_2$. We find that recent measurements of the nonlinear refractive index ($n_2$) in [J.K. Wahlstrand et al., Phys. Rev. A. 85, 043820 (2012)] provide the best match and an excellent fit between experiments and simulations.

Rosenthal, E W; Jhajj, N; Zahedpour, S; Wahlstrand, J K; Milchberg, H M

2014-01-01T23:59:59.000Z

424

Transcriptomic and physiological insights into the robustness of UASB granule-prevalent long filamentous cells of Methanosaeta harundinacea  

Science Journals Connector (OSTI)

...quantitative reverse transcription PCR indicated that transcription of the genes involved in aceticlastic methanogenesis and energy metabolism was upregulated 1.2- to 10.3-fold in long filaments, while those for the methyl-oxidative shunt were upregulated...

Liguang Zhou; Haiying Yu; Guomin Ai; Bo Zhang; Songnian Hu; Xiuzhu Dong

2014-11-14T23:59:59.000Z

425

3D Simulations of Plasma Filaments in the Scrape Off Layer: A Comparison with Models of Reduced Dimensionality  

E-Print Network (OSTI)

This paper presents simulations of isolated 3D filaments in a slab geometry obtained using a 3D reduced fluid code. First, systematic scans were performed to investigate how the dynamics of a filament are affected by its amplitude, perpendicular size and parallel extent. The perpendicular size of the filament was found to have a strong influence on its motions, as it determined the relative importance of parallel currents to polarisation and viscous currents, whilst drift-wave instabilities were observed if the initial amplitude of the blob was increased sufficiently. Next, the 3D simulations were compared to 2D simulations using different parallel closures; namely, the sheath dissipation closure, which neglects parallel gradients, and the vorticity advection closure, which neglects the influence of parallel currents. The vorticity advection closure was found to not replicate the 3D perpendicular dynamics and overestimated the initial radial acceleration of all the filaments studied. In contrast, a more satis...

Easy, Luke; Omotani, John; Dudson, Benjamin; Havl?kov, Eva; Tamain, Patrick; Naulin, Volker; Nielsen, Anders H

2014-01-01T23:59:59.000Z

426

Automated Technique For Comparison Of Magnetic Field Inversion Lines With Filament Skeletons From The Solar Feature Catalogue  

Science Journals Connector (OSTI)

We present an automated technique for comparison of magnetic field inversion-line maps from SOHO/MDI magnetograms with solar ... component labelling are used to identify nearest inversion lines to filament skelet...

S. S. Ipson; V. V. Zharkova; S. Zharkov; A. K. Benkhalil; J. Aboudarham

2005-05-01T23:59:59.000Z

427

Deposition of device quality, low hydrogen content, amorphous silicon films by hot filament technique using ``safe`` silicon source gas  

DOE Patents (OSTI)

A method is described for producing hydrogenated amorphous silicon on a substrate by flowing a stream of safe (diluted to less than 1%) silane gas past a heated filament. 7 figs.

Mahan, A.H.; Molenbroek, E.C.; Nelson, B.P.

1998-07-07T23:59:59.000Z

428

Identification of coronal holes and filament channels in SDO/AIA 193\\r{A} images via geometrical classification methods  

E-Print Network (OSTI)

In this study, we describe and evaluate shape measures for distinguishing between coronal holes and filament channels as observed in Extreme Ultraviolet (EUV) images of the Sun. For a set of well-observed coronal hole and filament channel regions extracted from SDO/AIA 193\\r{A} images we analyze their intrinsic morphology during the period 2011 to 2013, by using well known shape measures from the literature and newly developed geometrical classification methods. The results suggest an asymmetry in the morphology of filament channels giving support for the sheared arcade or weakly twisted flux rope model for filaments. We find that the proposed shape descriptors have the potential to reduce coronal hole classification errors and are eligible for screening techniques in order to improve the forecasting of solar wind high-speed streams from coronal hole observations in solar EUV images.

Reiss, M; Rotter, T; Hofmeister, S J; Veronig, A M

2014-01-01T23:59:59.000Z

429

Filaments of the radio cosmic web: opportunities and challenges for SKA  

E-Print Network (OSTI)

The detection of the diffuse gas component of the cosmic web remains a formidable challenge. In this work we study synchrotron emission from the cosmic web with simulated SKA1 observations, which can represent an fundamental probe of the warm-hot intergalactic medium. We investigate radio emission originated by relativistic electrons accelerated by shocks surrounding cosmic filaments, assuming diffusive shock acceleration and as a function of the (unknown) large-scale magnetic fields. The detection of the brightest parts of large ($>10 \\rm Mpc$) filaments of the cosmic web should be within reach of the SKA1-LOW, if the magnetic field is at the level of a $\\sim 10$ percent equipartition with the thermal gas, corresponding to $\\sim 0.1 \\mu G$ for the most massive filaments in simulations. In the course of a 2-years survey with SKA1-LOW, this will enable a first detection of the "tip of the iceberg" of the radio cosmic web, and allow for the use of the SKA as a powerful tool to study the origin of cosmic magneti...

Vazza, Franco; Bonafede, Annalisa; Brggen, Marcus; Gheller, Claudio; Braun, Robert; Brown, Shea

2015-01-01T23:59:59.000Z

430

Protein-Nanocrystal Conjugates Support a Single Filament Polymerization Model in R1 Plasmid Segregation  

SciTech Connect

To ensure inheritance by daughter cells, many low-copy number bacterial plasmids, including the R1 drug-resistance plasmid, encode their own DNA segregation systems. The par operon of plasmid R1 directs construction of a simple spindle structure that converts free energy of polymerization of an actin-like protein, ParM, into work required to move sister plasmids to opposite poles of rod-shaped cells. The structures of individual components have been solved, but little is known about the ultrastructure of the R1 spindle. To determine the number of ParM filaments in a minimal R1 spindle, we used DNA-gold nanocrystal conjugates as mimics of the R1 plasmid. Wefound that each end of a single polar ParM filament binds to a single ParR/parC-gold complex, consistent with the idea that ParM filaments bind in the hollow core of the ParR/parC ring complex. Our results further suggest that multifilament spindles observed in vivo are associated with clusters of plasmidssegregating as a unit.

Choi, Charina L.; Claridge, Shelley A.; Garner, Ethan C.; Alivisatos, A. Paul; Mullins, R. Dyche

2008-07-15T23:59:59.000Z

431

Robustness of the filamentation instability in arbitrarily oriented magnetic field: Full three dimensional calculation  

SciTech Connect

The filamentation (Weibel) instability plays a key role in the formation of collisionless shocks which are thought to produce Gamma-Ray-Bursts and High-Energy-Cosmic-Rays in astrophysical environments. While it has been known for long that a flow-aligned magnetic field can completely quench the instability, it was recently proved in 2D that in the cold regime, such cancelation is possible if and only if the field is perfectly aligned. Here, this result is finally extended to a 3D geometry. Calculations are conducted for symmetric and asymmetric counter-streaming relativistic plasma shells. 2D results are retrieved in 3D: the instability can never be completely canceled for an oblique magnetic field. In addition, the maximum growth-rate is always larger for wave vectors lying in the plan defined by the flow and the oblique field. On the one hand, this bears consequences on the orientation of the generated filaments. On the other hand, it certifies 2D simulations of the problem can be performed without missing the most unstable filamentation modes.

Bret, A., E-mail: antoineclaude.bret@uclm.es [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain and Instituto de Investigaciones Energticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain)

2014-02-15T23:59:59.000Z

432

genBRDF: Synthesizing Novel Analytic BRDFs with Genetic Programming Figure 1: Comparison of BRDFs modeling the tungsten carbide material from the MERL BRDF database. Each scene consists of a sphere  

E-Print Network (OSTI)

of BRDFs modeling the tungsten carbide material from the MERL BRDF database. Each scene consists that remains between state-of-the-art analytic BRDFs and measured data in the case of tungsten carbide

Weimer, Westley

433

Process for the production of hydrogen and carbonyl sulfide from hydrogen sulfide and carbon monoxide using a metal boride, nitride, carbide and/or silicide catalyst  

SciTech Connect

Hydrogen and carbonyl sulfide are produced by a process comprising contacting gaseous hydrogen sulfide with gaseous carbon monoxide in the presence of a metal boride, carbide, nitride and/or silicide catalyst, such as titanium carbide, vanadium boride, manganese nitride or molybdenum silicide.

McGuiggan, M.F.; Kuch, P.L.

1984-05-08T23:59:59.000Z

434

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

E-Print Network (OSTI)

of hydrocarbon dissociation on transition metal (TM) sur- faces represents a challenging way to its synthesisGrowth of Dome-Shaped Carbon Nanoislands on Ir(111): The Intermediate between Carbidic Clusters coupled carbidic carbon and a quasi-free-standing graphene layer, can provide information for a rational

Alfè, Dario

435

The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers  

SciTech Connect

Silicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6{trademark} silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess carbon was added during the CVD process. The concentration, homogeneity, and distribution of carbon were measured using energy dispersive x-ray spectroscopy (SEM/EDS). The effect of excess carbon on the tensile strength, elastic modulus, and the crystallographic and microstructural properties of CVD silicon carbide fibers was investigated using tensile testing, x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Marzik, J V; Croft, W J; Staples, R J; MoberlyChan, W J

2006-12-05T23:59:59.000Z

436

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

SciTech Connect

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.

Buss, R.J.

1997-02-01T23:59:59.000Z

437

On the genesis of molybdenum carbide phases during reduction-carburization reactions  

SciTech Connect

Molybdenum carbide has been prepared according to the carbothermal reduction method. Carbon black substrate was used as C-source whereas a H{sub 2}-flow was the reducing agent. Two different H{sub 2} consumption steps were identified during the carburization treatment. The low temperature step is related to the reduction of Mo{sup 6+}-to-Mo{sup 4+}, the higher temperature process accounts for the deep reduction of Mo{sup 4+}-to-metal Mo{sup 0} and its subsequent reaction with C to form the Mo-carbide. The influences of the maximum carburization temperature, carburization time, gas hourly space velocity regarding Mo-loading, heating rate and temperature of Ar pre-treatment were analyzed. All these conditions are interrelated to each other. Thus, the carburization process ends at 700 Degree-Sign C when Mo-loading is 10 wt%, however Mo-loading higher than 10 wt% requires higher temperatures. Carburization temperatures up to 800 Degree-Sign C are needed to fulfill Mo-carbide formation with samples containing 50 wt% Mo. Nevertheless, Ar pre-treatment at 550 Degree-Sign C and slow heating rates favor the carburization, thus requiring lower carburization temperatures to reach the same carburization level. - Graphical Abstract: H{sub 2}-consumption profile (TPR) during the molybdenum carburization process, XRD patterns of the reduced Mo-samples after carburization and TEM-micrographs with two different enlargement of the samples with 5, 20 and 50 wt% Mo. Highlights: Black-Right-Pointing-Pointer Control of carburization variables: tailor the reduced/carbide Mo-phases (single/mixture). Black-Right-Pointing-Pointer Mo carburization in two stages: (1) Mo{sup 6+}-Mo{sup 4+}; (2) Mo{sup 4+}-Mo{sup 0} and, at once, MoC. Black-Right-Pointing-Pointer The carburization process is faster than Mo{sup 4+} reduction. Black-Right-Pointing-Pointer XPS probed: reduced Mo particles show core-shell structure. Black-Right-Pointing-Pointer Core: reduced Mo (Mo{sub 2}C, MoO{sub 2} and/or Mo{sup 0}); Shell: 2-3 nm of MoO{sub 3}.

Guil-Lopez, R., E-mail: rut.guil@icp.csic.es [Grupo de Energia y Quimica Sostenibles, ICP-CSIC, Marie Curie 2, Cantoblanco, 28049-Madrid (Spain); Nieto, E. [Grupo de Energia y Quimica Sostenibles, ICP-CSIC, Marie Curie 2, Cantoblanco, 28049-Madrid (Spain); Departamento de Tecnologia Quimica y Energetica, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933-Mostoles (Spain); Botas, J.A. [Departamento de Tecnologia Quimica y Energetica, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933-Mostoles (Spain); Fierro, J.L.G., E-mail: jlgfierro@icp.csic.es [Grupo de Energia y Quimica Sostenibles, ICP-CSIC, Marie Curie 2, Cantoblanco, 28049-Madrid (Spain)

2012-06-15T23:59:59.000Z

438

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

E-Print Network (OSTI)

Ni S Al Zr V Mn Co Mg, Cu, Mo Quantity (Weight 4) by Chemical Analysis 98 ' 5 0. 6 0. 2 0. 03 0. 60 Quantity (ppm) by Spectrographic Analysis 400 170 130 35 15 150 300 70 250 25 10 10 is smaller than for the silicon carbide... 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...

Oakeson, David Oscar

1992-01-01T23:59:59.000Z

439

All-optical coherent population trapping with defect spin ensembles in silicon carbide  

E-Print Network (OSTI)

Divacancy defects in silicon carbide have long-lived electronic spin states and sharp optical transitions, with properties that are similar to the nitrogen-vacancy defect in diamond. We report experiments on 4H-SiC that investigate all-optical addressing of spin states with the zero-phonon-line transitions. Our magneto-spectroscopy results identify the spin $S=1$ structure of the ground and excited state, and a role for decay via intersystem crossing. We use these results for demonstrating coherent population trapping of spin states with divacancy ensembles that have particular orientations in the SiC crystal.

Olger V. Zwier; Danny O'Shea; Alexander R. Onur; Caspar H. van der Wal

2014-11-06T23:59:59.000Z

440

Electronic Structure and Chemical Bonding of Amorphous Chromium Carbide Thin Films  

E-Print Network (OSTI)

The microstructure, electronic structure, and chemical bonding of chromium carbide thin films with different carbon contents have been investigated with high-resolution transmission electron microscopy, electron energy loss spectroscopy and soft x-ray absorption-emission spectroscopies. Most of the films can be described as amorphous nanocomposites with non-crystalline CrCx in an amorphous carbon matrix. At high carbon contents, graphene-like structures are formed in the amorphous carbon matrix. At 47 at% carbon content, randomly oriented nanocrystallites are formed creating a complex microstructure of three components. The soft x-ray absorption-emission study shows additional peak structures exhibiting non-octahedral coordination and bonding.

Magnuson, Martin; Lu, Jun; Hultman, Lars; Jansson, Ulf; 10.1088/0953-8984/24/22/225004

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Formation of graphene layers by vacuum sublimation of silicon carbide using a scanning heat source  

SciTech Connect

The kinetics of surface graphitization during dissociative vacuum evaporation of silicon carbide, under the effect of a scanning heat source, is studied. A model of the process is developed. The model provides a means for theoretically treating the dynamics of formation and the number of residual carbon atomic layers. The vapor stoichiometric coefficient which ensures the minimization of the number of structural defects in graphene, is optimized at the sublimation temperature: {theta} = 1/{eta}(T{sub max}). The proposed method can be used as a basis for graphene production technology.

Dmitriev, A. N.; Cherednichenko, D. I., E-mail: cheredni@fep.tti.sfedu.ru [Southern Federal University, Taganrog Technological Institute (Russian Federation)

2011-12-15T23:59:59.000Z

442

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

SciTech Connect

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.

Hain, T. C.; Hertel, T. [Institute of Physical and Theoretical Chemistry, Julius-Maximilian University of Wrzburg, 97074 Wrzburg (Germany); Fuchs, F.; Astakhov, G. V., E-mail: astakhov@physik.uni-wuerzburg.de [Experimental Physics VI, Julius-Maximilian University of Wrzburg, 97074 Wrzburg (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 Wrzburg, 97074 Wrzburg (Germany); Bavarian Center for Applied Energy Research (ZAE Bayern), 97074 Wrzburg (Germany)

2014-04-07T23:59:59.000Z

443

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

SciTech Connect

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.

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

444

A visible light-sensitive tungsten carbide/tungsten trioxde composite photocatalyst  

SciTech Connect

A photocatalyst composed of tungsten carbide (WC) and tungsten oxide (WO{sub 3}) has been prepared by the mechanical mixing of each powder. Its photocatalytic activity was evaluated by the gaseous isopropyl alcohol decomposition process. The photocatalyst showed high visible light photocatalytic activity with a quantum efficiency of 3.2% for 400-530 nm light. The photocatalytic mechanism was explained by means of enhanced oxygen reduction reaction due to WC, which may serve as a multielectron reduction catalyst, as well as the photogeneration of holes in the valence band of WO{sub 3}.

Kim, Young-ho [Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Irie, Hiroshi [Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Hashimoto, Kazuhito [Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2008-05-05T23:59:59.000Z

445

Mechanical Instability and Ideal Shear Strength of Transition Metal Carbides and Nitrides  

SciTech Connect

The ideal shear strength of transition metal carbides and nitrides is calculated with the use of the ab initio pseudopotential density functional method. The microscopic mechanism that limits the ideal strength is studied using full atomic and structural relaxation and the results of electronic structure calculations. It is shown that plasticity in perfect crystals can be triggered by electronic instabilities at finite strains. Our study explicitly demonstrates that the ideal strength in these materials is limited by the elastic instability which is in turn initiated by electronic instabilities. The potential application of alloy hardening due to the onset of instabilities at different strains is also discussed.

Jhi, Seung-Hoon; Louie, Steven G.; Cohen, Marvin L.; Morris, J. W.

2001-08-13T23:59:59.000Z

446

JOURNAL DE PHYSIQUE Colloque C2,supplkment au n o 3, Tome 40, mars 1979,page C2-627 DETERMINATION OF RETAINED AUSTENITE IN STEELS ALLOYED WITH CARBIDE FORMERS  

E-Print Network (OSTI)

OF RETAINED AUSTENITE IN STEELS ALLOYED WITH CARBIDE FORMERS E. Kuzmann, L. Domonkos. M. Kocsis, S for the quantitative determination of the retained austenite in steels alloyed with carbide forming elements. By means of this method, the disturbing effect of the paramagnetic carbides containing iron can be eliminated

Paris-Sud XI, Université de

447

Solar-to-Hydrogen Photovoltaic/Photoelectrochemical Devices Using Amorphous Silicon Carbide as the Photoelectrode  

SciTech Connect

We report the use of hydrogenated amorphous silicon carbide (a-SiC:H) prepared by plasma enhanced chemical vapor deposition (PECVD) as the photoelectrode in an integrated 'hybrid' photoelectrochemical (PEC) cell to produce hydrogen directly from water using sunlight. Results on the durability of hydrogenated amorphous silicon carbide (a-SiC:H) photoelectrodes in an electrolyte are presented. In a pH2 electrolyte, the a-SiC:H photoelectrode exhibits excellent stability for 100 hour test so far performed. A photocurrent onset shift (anodically) after a 24- or 100-hour durability test in electrolyte is observed, likely due to changes in the surface chemical structure of the a-SiC:H photoelectrode. It is also observed that a thin SiOx layer native to the air exposed surface of the a-SiC:H affects the photocurrent and the its onset shift. Finally, approaches for eliminating the external bias voltage and enhancing the solar-to-hydrogen efficiency in a PV/PEC hybrid structure to achieve {>=} 10% are presented.

Hu, J.; Zhu, F.; Matulionis, I.; Kunrath, A.; Deutsch, T.; Kuritzky, L.; Miller, E.; Madan, A.

2008-01-01T23:59:59.000Z

448

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

SciTech Connect

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.

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

449

Irradiation-induced effects of proton irradiation on zirconium carbides with different stoichiometries  

SciTech Connect

Zirconium carbide (ZrC) is being considered for utilization in deep burn TRISO fuel particles for hightemperature, gas-cooled reactors. Zirconium carbide has a cubic B1 type crystal structure along with a very high melting point (3420 ?C), exceptional hardness and good thermal and electrical conductivities. Understanding the ZrC irradiation response is crucial for establishing ZrC as an alternative component in TRISO fuel. Until now, very few studies on irradiation effects on ZrC have been released and fundamental aspects of defect evolution and kinetics are not well understood although some atomistic simulations and phenomenological studies have been performed. This work was carried out to understand the damage evolution in float-zone refined ZrC with different stoichiometries. Proton irradiations at 800 ?C up to doses of 3 dpa were performed on ZrCx (where x ranges from 0.9 to 1.2) to investigate the damage evolution. The irradiation-induced defects, such as density of dislocation loops, at different stoichiometries and doses which were characterized by transmission electron microscopy (TEM) is presented and discussed.

Y. Huang; B.R. Maier; T.R. Allen

2014-10-01T23:59:59.000Z

450

Portraits of some representatives of metal boride carbide and boride silicide compounds  

SciTech Connect

Different ternary alkaline-earth and rare-earth metal boron carbide and silicide compounds are examined using the solid-state language of Zintl-Klemm concept, band structures, and density of states, in order to show that the topology of the non-metal sub-lattice is highly dependent on the electron count. It is also shown that the chemistry of rare-earth metal-boron-silicon does not parallel that of rare-earth metal-boron-carbon. B-C bonds are easily formed in the latter, leading to a large variety of different structural arrangements, whereas Si-B bonds are hardly observed in the former, except in insertion compounds. - Graphical abstract: Some ternary alkaline-earth and rare-earth metal boron carbide and silicide compounds are examined using the solid-state language of Zintl-Klemm concept, band structures, and density of states, in order to show that the topology of the non-metal sub-lattice is highly dependent on the electron count.

Ben Yahia, Mouna [Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511 CNRS-Universite de Rennes 1-ENSC Rennes, Institut de Chimie de Rennes, F-35042 Rennes (France); Roger, Jerome [Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511 CNRS-Universite de Rennes 1-ENSC Rennes, Institut de Chimie de Rennes, F-35042 Rennes (France); Rocquefelte, Xavier [Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511 CNRS-Universite de Rennes 1-ENSC Rennes, Institut de Chimie de Rennes, F-35042 Rennes (France); Gautier, Regis [Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511 CNRS-Universite de Rennes 1-ENSC Rennes, Institut de Chimie de Rennes, F-35042 Rennes (France); Bauer, Joseph [Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511 CNRS-Universite de Rennes 1-ENSC Rennes, Institut de Chimie de Rennes, F-35042 Rennes (France); Guerin, Roland [Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511 CNRS-Universite de Rennes 1-ENSC Rennes, Institut de Chimie de Rennes, F-35042 Rennes (France); Saillard, Jean-Yves [Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511 CNRS-Universite de Rennes 1-ENSC Rennes, Institut de Chimie de Rennes, F-35042 Rennes (France); Halet, Jean-Francois [Laboratoire de Chimie du Solide et Inorganique Moleculaire, UMR 6511 CNRS-Universite de Rennes 1-ENSC Rennes, Institut de Chimie de Rennes, F-35042 Rennes (France)]. E-mail: halet@univ-rennes1.fr

2006-09-15T23:59:59.000Z

451

Method for preparing configured silicon carbide whisker-reinforced alumina ceramic articles  

DOE Patents (OSTI)

A ceramic article of alumina reinforced with silicon carbide whiskers suitable for the fabrication into articles of complex geometry are provided by pressureless sintering and hot isostatic pressing steps. In accordance with the method of the invention a mixture of 5 to 10 vol. % silicon carbide whiskers 0.5 to 5 wt. % of a sintering aid such as yttria and the balance alumina powders is ball-milled and pressureless sintered in the desired configuration in the desired configuration an inert atmosphere at a temperature of about 1800.degree. C. to provide a self-supporting configured composite of a density of at least about 94% theoretical density. The composite is then hot isostatically pressed at a temperature and pressure adequate to provide configured articles of at least about 98% of theoretical density which is sufficient to provide the article with sufficient strength and fracture toughness for use in most structural applications such as gas turbine blades, cylinders, and other components of advanced heat engines.

Tiegs, Terry N. (Lenoir City, TN)

1987-01-01T23:59:59.000Z

452

Complete Genome Sequence of the Filamentous Anoxygenic Phototrophic Bacterium Chloroflexus aurantiacus  

SciTech Connect

Chloroflexus aurantiacus is a thermophilic filamentous anoxygenic phototrophic (FAP) bacterium, and can grow phototrophically under anaerobic conditions or chemotrophically under aerobic and dark conditions. According to 16S rRNA analysis, Chloroflexi species are the earliest branching bacteria capable of photosynthesis, and Cfl. aurantiacus has been long regarded as a key organism to resolve the obscurity of the origin and early evolution of photosynthesis. Cfl. aurantiacus contains a chimeric photosystem that comprises some characters of green sulfur bacteria and purple photosynthetic bacteria, and also has some unique electron transport proteins compared to other photosynthetic bacteria.

Tang, Kuo-Hsiang [Washington University, St. Louis; Barry, Kerrie [U.S. Department of Energy, Joint Genome Institute; Chertkov, Olga [Los Alamos National Laboratory (LANL); Dalin, Eileen [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Hauser, Loren John [ORNL; Honchak, Barbara M [Washington University, St. Louis; Karbach, Lauren E [Washington University, St. Louis; Land, Miriam L [ORNL; Lapidus, Alla L. [Joint Genome Institute, Walnut Creek, California; Larimer, Frank W [ORNL; Mikhailova, Natalia [U.S. Department of Energy, Joint Genome Institute; Pitluck, Sam [Joint Genome Institute, Walnut Creek, California; Pierson, Beverly K [University of Puget Sound, Tacoma, WA

2011-01-01T23:59:59.000Z

453

Infrared pulse characterization using four-wave mixing inside a few cycle pulse filament in air  

SciTech Connect

We demonstrate a four-wave mixing (FWM) technique to measure near- and mid-infrared (IR) laser pulse shapes in time domain. Few cycle 800?nm laser pulses were synchronized with the IR pulse and focused colinearly to generate a plasma filament in air. Second harmonic radiation around 400?nm was generated through FWM, with a yield proportional to the IR pulse intensity. Excellent signal to noise ratio was observed from 2.1??m to 18??m. With proper phase stabilization of the IR beam, this technique is a promising step toward direct electric field sensing of near-IR pulses in air.

Marceau, Claude, E-mail: claude.marceau.2@ulaval.ca; Thomas, Steven; Kassimi, Yacine; Gingras, Guillaume; Witzel, Bernd [Centre d'Optique, Photonique et Laser, Pavillon d'optique-photonique Qubec (Qubec), Universit Laval, Qubec G1V 0A6 (Canada)

2014-02-03T23:59:59.000Z

454

Sulfur-Emission-Free Process of Molybdenum Carbide Synthesis by Lime-Enhanced Molybdenum Disulfide Reduction with Methane  

Science Journals Connector (OSTI)

Sulfur-Emission-Free Process of Molybdenum Carbide Synthesis by Lime-Enhanced Molybdenum Disulfide Reduction with Methane ... Molybdenite (MoS2) concentrate is the major mineral for molybdenum extraction. ... This understanding is critical for practical application of this reaction to produce Mo2C in an economic and green process. ...

Samad Ghasemi; Mohammad Hasan Abbasi; Ali Saidi; Jae Yul Kim; Jae Sung Lee

2011-10-28T23:59:59.000Z

455

Deposition of high-density silicon carbide coatings by fluidized-bed pyrolysis of chlorinated silane derivatives  

Science Journals Connector (OSTI)

Comparative analysis of the processes for preparation of high-density silicon carbide coatings by the fluidized-bed pyrolysis of the SiCl4 + CH4 + H2 + Ar and CH3SiCl3 + H2 + Ar mixtures on pyrocarboncoated zirco...

S. D. Kurbakov; T. A. Mireev

2009-04-01T23:59:59.000Z

456

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

E-Print Network (OSTI)

jet will disrupt the pool, unless mitigated by a splash suppressor. A SOLENOID CAPTURE SYSTEM Collider (MC) Comments Beam Power 4 MW No existing target system will survive at this power Ep 8 GeV yieldAbove: Power deposition in the superconducting magnets and the tungsten-carbide + water shield

McDonald, Kirk

457

Theoretical Analysis of the Adsorption of Late Transition Metal Atoms on the (001) Surface of Early Transition Metal Carbides  

SciTech Connect

The interaction of atoms of Groups 9, 10, and 11 with the (001) surface of TiC, ZrC, VC, and {delta}-MoC has been studied by means of periodic density functional calculations using slab models. The calculated values of the adsorption energy are rather large, especially for Groups 9 and 10 elements (E{sub ads} = 3-6 eV), but without clear trends along the series. Nevertheless, the analysis of the interaction at different sites indicates that the adsorbed atoms will be relatively mobile. Many of the admetals are electronically perturbed upon interaction with the carbide surfaces. Co, Ni, Cu, and Rh adatoms get positively or negatively charged, depending on the nature of the carbide substrate. Ir, Pd, Pt, and Au adatoms are always negatively charged. An analysis of the Bader charges for the most stable sites provides strong evidence that the most negative charge on the adatoms corresponds to the interaction with ZrC, followed by TiC. In the case of VC and {delta}-MoC, the charge on the adsorbed atoms may be slightly positive and of the same order for both carbides. The effect of the underlying carbide is large, with ZrC and TiC being predicted as the supports with the largest effect on the electronic structure of the adsorbed atoms with direct implications for the use of these systems in catalysis.

Rodriguez, J.A.; Gmez, T.; Florez, E.; Illas, F.

2010-01-28T23:59:59.000Z

458

Remote generation of high-energy terahertz pulses from two-color femtosecond laser filamentation in air  

SciTech Connect

We experimentally investigated the dynamic behavior of remote terahertz (THz) generation from two-color femtosecond laser-induced filamentation in air. A record-high THz pulse energy of 570 nJ at frequency below 5.5 THz was measured by optimizing the pump parameters at a controllable remote distance of 16 m, while super-broadband THz (<300 THz) pulse energy was up to 2.8 {mu}J. A further energy-scaling possibility was proposed. By analyzing simultaneously the fluorescence from both neutral N{sub 2} and N{sub 2}{sup +} in the filament, we found that the enhancement of THz radiation was due principally to guiding of the weak second-harmonic pulse inside the filament of the first strong fundamental pulse.

Wang, T.-J.; Daigle, J.-F.; Yuan, S.; Chin, S. L. [Centre d'Optique, Photonique et Laser (COPL) and Departement de physique, de genie physique et d'optique, Universite Laval, Quebec, Quebec G1V 0A6 (Canada); Theberge, F.; Chateauneuf, M.; Dubois, J.; Roy, G. [Defence Research and Development Canada-Valcartier, 2459 Pie-XI Boulevard North, Quebec, Quebec G3J 1X5 (Canada); Zeng, H. [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

2011-05-15T23:59:59.000Z

459

Observational evidence of torus instability as trigger mechanism for coronal mass ejections: the 2011 August 4 filament eruption  

E-Print Network (OSTI)

Solar filaments are magnetic structures often observed in the solar atmosphere and consist of plasma that is cooler and denser than their surroundings. They are visible for days -- and even weeks -- which suggests that they are often in equilibrium with their environment before disappearing or erupting. Several eruption models have been proposed that aim to reveal what mechanism causes (or triggers) these solar eruptions. Validating these models through observations represents a fundamental step in our understanding of solar eruptions. We present an analysis of the observation of a filament eruption that agrees with the torus instability model. This model predicts that a magnetic flux rope embedded in an ambient field undergoes an eruption when the axis of the flux rope reaches a critical height that depends on the topology of the ambient field. We use the two vantage points of SDO and STEREO to reconstruct the three-dimensional shape of the filament, to follow its morphological evolution and to determine its...

Zuccarello, Francesco P; Mierla, Marilena; Poedts, Stefaan; Rachmeler, Laurel A; Romano, Paolo; Zuccarello, Francesca

2014-01-01T23:59:59.000Z

460

Intensity clamping measurement of laser filaments in air at 400 and 800 nm  

SciTech Connect

Molecular N{sub 2} fluorescence excited by laser filaments formed from laser pulses at 400 and 800 nm propagating in air is investigated. A comparison showed that, when excited with 400 nm photons, the fluorescence from the first negative band of N{sub 2}{sup +} was enhanced by a factor of 6.4 while that of the second positive band of neutral N{sub 2} remained relatively constant. The enhanced N{sub 2}{sup +} signal is attributed to a more efficient inner-shell multiphoton process (to the B{sup 2{Sigma}}{sub u}{sup +} state) at 400 nm leaving a larger population of N{sub 2}{sup +} ions in the excited state. On the other hand, the stable fluorescence from neutral N{sub 2} is due to the fact that the plasma density is more or less the same at both wavelengths. Using these results, a theoretical model is developed to determine the clamped intensities of the laser filaments at 400 and 800 nm.

Daigle, J.-F.; Hosseini, S.; Wang, T.-J.; Kamali, Y.; Chin, S. L. [Centre d'Optique, Photonique et Laser (COPL) and Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1V 0A6 (Canada); Jaron-Becker, A.; Becker, A. [JILA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440 (United States); Roy, G. [Defence Research and Development Canada-Valcartier, 2459 Pie-XI Boulevard North, Quebec, Quebec G3J 1X5 (Canada)

2010-08-15T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Oil filaments produced by an impeller in a water stirred thank  

E-Print Network (OSTI)

In this video, the mechanism followed to disperse an oil phase in water using a Scaba impeller in a cylindrical tank is presented. Castor oil (viscosity = 500 mPas) is used and the Reynolds number was fixed to 24,000. The process was recorded with a high-speed camera. Initially, the oil is at the air water interface. At the beginning of the stirring, the oil is dragged into the liquid bulk and rotates around the impeller shaft, then is pushed radially into the flow ejected by the impeller. In this region, the flow is turbulent and exhibits velocity gradients that contribute to elongate the oil phase. Viscous thin filaments are generated and expelled from the impeller. Thereafter, the filaments are elongated and break to form drops. This process is repeated in all the oil phase and drops are incorporated into the dispersion. Two main zones can be identified in the tank: the impeller discharge characterized by high turbulence and the rest of the flow where low velocity gradients appear. In this region surface f...

Sanjuan-Galindo, Rene; Ascanio, Gabriel; Zenit, Roberto

2010-01-01T23:59:59.000Z

462

Fused-filament 3D printing (3DP) for fabrication of tablets  

Science Journals Connector (OSTI)

Abstract The use of fused-filament 3D printing (FF 3DP) to fabricate individual tablets is demonstrated. The technology permits the manufacture of tablets containing drug doses tailored to individual patients, or to fabrication of tablets with specific drug-release profiles. Commercially produced polyvinyl alcohol (PVA) filament was loaded with a model drug (fluorescein) by swelling of the polymer in ethanolic drug solution. A final drug-loading of 0.29% w/w was achieved. Tablets of PVA/fluorescein (10mm diameter) were printed using a 3D printer. It was found that changing the degree of infill percentage in the printer software varied the weight and volume of the printed tablets. The tablets were mechanically strong and no significant thermal degradation of the active occurred during printing. Dissolution tests were conducted in modified Hanks buffer. The results showed release profiles were dependent on the infill percentage used to print the tablet. The study indicates that FF 3DP has the potential to offer a new solution for fabricating personalized-dose medicines or unit dosage forms with controlled-release profiles. In addition, the low cost of FDM printers means the paradigm of extemporaneous or point-of-use manufacture of personalized-dose tablets is both feasible and attainable.

Alvaro Goyanes; Asma B.M. Buanz; Abdul W. Basit; Simon Gaisford

2014-01-01T23:59:59.000Z

463

A theoretical study of the incandescent filament lamp performance under voltage flicker  

SciTech Connect

Incandescent filament lamp flicker, produced by voltage fluctuation, is a power quality problem that caused engineering concern since the onset of electrical illumination technology. The flicker phenomenon was analyzed and explained in early studies. Standards dealing with acceptable flicker levels are well known, nevertheless, today the discussion about flicker continues to be a top priority topic due to the fact that steady-state and transient voltage waveform distortion is a growing problem in low and medium voltage systems. In many situations voltage flicker is caused by subharmonics and interharmonics of voltage. Cycloconverters, welders and arc furnaces, eccentrically operating tools and integral cycle controlled power equipment are notorious for producing voltage flicker. The goal of this paper is to provide solid mathematical basis for the analytical modeling of incandescent filament lamp flicker when the voltage is nonsinusoidal. A mathematical model that enables the evaluation of the luminous flux modulation caused by noninteger harmonics (subharmonics and interharmonics) is presented. Three situations are detailed: square-wave voltage modulation, sinusoidal modulation and the case of noninteger harmonics with nearly contiguous frequencies.

Peretto, L. [Univ. of Bologna (Italy)] [Univ. of Bologna (Italy); Emanuel, A.E. [Worcester Polytechnic Inst., MA (United States)] [Worcester Polytechnic Inst., MA (United States)

1997-01-01T23:59:59.000Z

464

B2223 High Temperature Superconductor Wires in Silver Sheath, Filament Diameter Effect on Critical Temperature and Current Density  

Science Journals Connector (OSTI)

B2223 High Temperature Superconductor (HTSC) has been prepared as a pellet by solid state reaction. Then, HTSC wires were fabricated from the prepared superconductor using powder in tube (PIT) method utilizing silver as the tube material. Superconductor powder was packed in the pure silver tube of about 4.5mm diameter, and 50mm long. The prepared wires are of three types; with monofilament MOF, 9 multifilament core (9MF) and 81 filaments core(81MF). Several cycles of mechanical are drawing and rolling process performed to the starting silver tube of 0.4cm diameter and 5cm length and 0.35mm thickness to minimize the filament diameter. The average filament diameter of MoC with 0.7mm SC core which was produce by the first step of drawing, the second 9 MF wire with nine multifilament wire of 0.175mm diameter for each filament,while the 81MFC wire filament diameter was about 25?m for each filament measured with an optical microscope. All the three types of wires were with same outer diameter of 0.9mm. Tc critical temperature for superconductivity is measured for the pellet and wires using four point probes techniques. The critical temperature for the pellet is 110 K, for the monofilament MOF is 112.5 K and for 9 filaments 9MF was found is 117K; while the Tc the 81MF was 119.5K. The critical current density for the 9MF and 81MF wires were found higher than that of the monofilament MOF in spite of the smaller filament diameters of the 9 MF and 81MF. X-ray diffraction pattern shows the high Tc phase of B2223 compounds in addition to low phase, of B2212 compounds. The I-V curves for the three different wires show higher current density for 81 MF wire, while the optical microscope picture shows more grains alignment . MOC and 9 MF wires show misalignment grains.

Akram R. Jabur

2012-01-01T23:59:59.000Z

465

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

SciTech Connect

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.

Nixdorf, R.D.

1999-04-01T23:59:59.000Z

466

OAK RIDGE NATIONAL LABORATORY OPER*TEO BY UNION CARBIDE CORPORATION  

Office of Legacy Management (LM)

~$ ., . .Y.' ~$ ., . .Y.' ~. : ' : ,,, OAK RIDGE NATIONAL LABORATORY OPER*TEO BY UNION CARBIDE CORPORATION NUCLEAR DIVISION ' . ' : .m POST OFFICE BOX X OAK RIDGE, TENNESSEE ,X,0 ,. June 20, 1980 .~ ,, M r. Arthur J. 'Whitman Environmental and Safety 'Engineering Division U.S. Department of Energy ,) Washington, Oit. 20545 ., Dear Art: Soil Sample Analysis, City of Woburn Landfill, Woburn, Massachusetts ,,During a.radiological survey of the old.and new city of Woburn landfills (i-e: trip report.to Woburn, Massachusetts, A. J. Whitman to W . E. Mott, Gecember 7, 1979), six,soil. samples were collected and analyzed by gamma spectrometry and neutron absorption methods. The results of,these analyses'are given. below. ,.~ ,. 226Ra "'Th 238u - pci/g pciJcJ pci/g Sampl .y

467

I' I OAK RIDGE NATIONAL LABORATORY OPERATED B Y UNION CARBIDE CORPORATION  

Office of Legacy Management (LM)

/ / I' I OAK RIDGE NATIONAL LABORATORY OPERATED B Y UNION CARBIDE CORPORATION NUCLEAR DIVISION POST OFFICE BOK X OAK RIDGE, TENNESSEE 37830 August 21, 1979 Department of Energy, Oak Ridge Operations Attention: E. L. Keller, Director for Technical Services Division Post Office Box E Oak Ridge, Tennessee 37830 Gentlemen: Formerly Utilized Site-Remedial Action Program - Post Decontamination Radiological Survey of a portion of the Former Kellex Laboratory Site, Jersey City, New Jersey Decontamination of three (3) small land areas on the Levco portion of the former Kellex Laboratory site was completed by the Tobar Construction Company during the week ending August 11, 1979. Health physics and environmental monitoring services during clean-up operations were provided

468

ESS 2012 Peer Review - Experimental Investigation of Silicon Carbide Power Device Reliability - Robert Kaplar, SNL  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Experimental Investigation Experimental Investigation of Silicon Carbide Power Device Reliability September 27, 2012 Robert Kaplar, David Hughart, Sandeepan DasGupta, Matthew Marinella, Mark Smith, and Stanley Atcitty The authors gratefully acknowledge the support of Dr. Imre Gyuk of the United States Department of Energy, Office of Electricity Delivery and Energy Reliability, Energy Storage Program * Wide-bandgap semiconductors have material properties that make them theoretically superior to Silicon for power device applications * Lower power loss and reduced cooling requirements would increase the efficiency and reduce the size and complexity of power conversion systems linking energy storage to the grid, thus reducing overall system cost * However, wide-bandgap materials and devices are far less mature

469

SILICON CARBIDE MICRO-DEVICES FOR COMBUSTION GAS SENSING UNDER HARSH CONDITIONS  

SciTech Connect

A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen containing species in chemically reactive, high temperature environments. Robust metallization and electrical contacting techniques have been developed for device operation at elevated temperatures. To characterize the time response of the sensor responses in the millisecond range, a conceptually new apparatus has been built. Software has been developed to cope with the requirements of fast sensor control and data recording. In addition user friendly software has been developed to facilitate use of the SiC sensors for industrial process control applications.

Ruby N. Ghosh; Peter Tobias; Roger G. Tobin

2004-04-01T23:59:59.000Z

470

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

DOE Patents (OSTI)

A method for the preparation of thin, free-standing metal oxide films which are useful as nuclear accelerator target materials. 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.

Quinby, Thomas C. (Kingston, TN)

1985-01-01T23:59:59.000Z

471

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

DOE Patents (OSTI)

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.

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

1994-01-01T23:59:59.000Z

472

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

DOE Patents (OSTI)

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.

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

1994-11-01T23:59:59.000Z

473

Near-Field Radiative Heat Transfer between Metamaterials coated with Silicon Carbide Film  

E-Print Network (OSTI)

In this letter, we study the near-field radiative heat transfer between two metamaterial substrates coated with silicon carbide (SiC) thin films. It is known that metamaterials can enhance the near-field heat transfer over ordinary materials due to excitation of magnetic plasmons associated with s polarization, while strong surface phonon polariton exists for SiC.By careful tuning of the optical properties of metamaterial it is possible to excite electrical and magnetic resonance for the metamaterial and surface phonon polaritons for SiC at different spectral regions, resulting in the enhanced heat transfer. The effect of the SiC film thickness at different vacuum gaps is investigated. Results obtained from this study will be beneficial for application of thin film coatings for energy harvesting.

Basu, Soumyadipta; Wang, Liping

2014-01-01T23:59:59.000Z

474

Quantum-confined single photon emission at room temperature from Silicon carbide tetrapods  

E-Print Network (OSTI)

Controlled engineering of isolated solid state quantum systems is one of the most prominent goals in modern nanotechnology. In this letter we demonstrate a previously unknown quantum system namely silicon carbide tetrapods. The tetrapods have a cubic polytype core (3C) and hexagonal polytype legs (4H) a geometry that creates a spontaneous polarization within a single tetrapod. Modeling of the tetrapod structures predict that a bound exciton should exist at the 3C 4H interface. The simulations are confirmed by the observation of fully polarized and narrowband single photon emission from the tetrapods at room temperature. The single photon emission provides important insights towards understanding the quantum confinement effects in non-spherical nanostructures. Our results pave the way to a new class of crystal phase nanomaterials that exhibit single photon emission at room temperature and therefore are suitable for sensing, quantum information and nanophotonics.

Castelletto, Stefania; Magyar, Andrew P; Gentle, Angus; Gali, Adam; Aharonovich, Igor

2014-01-01T23:59:59.000Z

475

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

E-Print Network (OSTI)

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.

Radulaski, Marina; Mller, Kai; Lagoudakis, Konstantinos G; Zhang, Jingyuan Linda; Buckley, Sonia; Kelaita, Yousif A; Alassaad, Kassem; Ferro, Gabriel; Vu?kovi?, Jelena

2014-01-01T23:59:59.000Z

476

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

E-Print Network (OSTI)

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.

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

2014-12-08T23:59:59.000Z

477

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

SciTech Connect

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.

Valentn, 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

478

Use of Silicon Carbide as Beam Intercepting Device Material: Tests, Issues and Numerical Simulations  

E-Print Network (OSTI)

Silicon Carbide (SiC) stands as one of the most promising ceramic material with respect to its thermal shock resistance and mechanical strengths. It has hence been considered as candidate material for the development of higher performance beam intercepting devices at CERN. Its brazing with a metal counterpart has been tested and characterized by means of microstructural and ultrasound techniques. Despite the positive results, its use has to be evaluated with care, due to the strong evidence in literature of large and permanent volumetric expansion, called swelling, under the effect of neutron and ion irradiation. This may cause premature and sudden failure, and can be mitigated to some extent by operating at high temperature. For this reason limited information is available for irradiation below 100C, which is the typical temperature of interest for beam intercepting devices like dumps or collimators. This paper describes the brazing campaign carried out at CERN, the results, and the theoretical and numeric...

Delonca, M; Gil Costa, M; Vacca, A

2014-01-01T23:59:59.000Z

479

Evaluation of microstructural damage and alteration of polytypes to determine the aging of silicon carbide  

SciTech Connect

Irradiated silicon carbide (SiC) exhibits higher carrier content but a decrease in conductivity with increased irradiation. It was theorized that this conflicting data was due to structural damage due to irradiation. This theory was supported by the fact that non-irradiated 50{mu}m thick SiC is transparent for visible light and the higher the irradiation dose, the material of the same thickness became less transparent. However, changes in microscopy and polyforms observed by transmission electron microscopy in SiC due to irradiation were minor. Although existence of different polymorphs of SiC was documented, direct proof of the proposed theory has not yet been achieved.

Koenig, T. W.; Mishra, B.; Olson, D. L. [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401 (United States); Meshi, L.; Foxman, Z.; Landau, A. [Ben-Gurion University of the Negev at Beer-Sheva, P.O.B. 653 Beer Sheva, 84105 (Israel); Riesterer, J. L.; Kennedy, J. R. [Advanced Test Reactor, Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

2013-01-25T23:59:59.000Z

480

Standard test methods for chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade boron carbide  

E-Print Network (OSTI)

1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade boron carbide powder and pellets to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Sections Total Carbon by Combustion and Gravimetry 7-17 Total Boron by Titrimetry 18-28 Isotopic Composition by Mass Spectrometry 29-38 Chloride and Fluoride Separation by Pyrohydrolysis 39-45 Chloride by Constant-Current Coulometry 46-54 Fluoride by Ion-Selective Electrode 55-63 Water by Constant-Voltage Coulometry 64-72 Impurities by Spectrochemical Analysis 73-81 Soluble Boron by Titrimetry 82-95 Soluble Carbon by a Manometric Measurement 96-105 Metallic Impurities by a Direct Reader Spectrometric Method 106-114

American Society for Testing and Materials. Philadelphia

2004-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "filament hafnium carbide" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

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

SciTech Connect

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.

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

1994-12-31T23:59:59.000Z

482

Effect of nanosilicon carbide on the carbonisation process of coal tar pitch  

Science Journals Connector (OSTI)

Abstract The study describes the effect of silicon carbide (SiC) nanopowder on the process of coal tar pitch thermal decomposition during heat treatment to a temperature of 2000C. The influence of nanosized SiC powder on the pyrolysis mechanism of carbonisation product yield, as well as structural and microstructural parameters of carbon obtained via carbonisation and further heating up to 2000C was studied. The results show that the incorporation of a suitable amount of ceramic nanopowder into the liquid coal tar pitch results in a decrease in the crystallite sizes of carbon residue, while further heating up to 2000C gives rise to two carbon phases, differing in crystallinity and interplanar distance between graphene layers. The SiC addition enhances the formation of well-ordered graphite domains in comparison with those present within a pure carbon matrix.

Danuta Mikociak; Anna Magiera; Grzegorz Labojko; Stanislaw Blazewicz

2014-01-01T23:59:59.000Z

483

Interaction of noble-metal fission products with pyrolytic silicon carbide  

SciTech Connect

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain layers of pyrolytic carbon and silicon carbide, which act as a miniature pressure vessel and form the primary fission product barrier. Of the many fission products formed during irradiation, the noble metals are of particular interest because they interact significantly with the SiC layer and their concentrations are somewhat higher in the low-enriched uranium fuels currently under consideration. To study fission product-SiC interactions, particles of UO/sub 2/ or UC/sub 2/ are doped with fission product elements before coating and are then held in a thermal gradient up to several thousand hours. Examination of the SiC coatings by TEM-AEM after annealing shows that silver behaves differently from the palladium group.

Lauf, R.J.; Braski, D.N.

1982-01-01T23:59:59.000Z

484

Stress testing on silicon carbide electronic devices for prognostics and health management.  

SciTech Connect

Power conversion systems for energy storage and other distributed energy resource applications are among the drivers of the important role that power electronics plays in providing reliable electricity. Wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) will help increase the performance and efficiency of power electronic equipment while condition monitoring (CM) and prognostics and health management (PHM) will increase the operational availability of the equipment and thereby make it more cost effective. Voltage and/or temperature stress testing were performed on a number of SiC devices in order to accelerate failure modes and to identify measureable shifts in electrical characteristics which may provide early indication of those failures. Those shifts can be interpreted and modeled to provide prognostic signatures for use in CM and/or PHM. Such experiments will also lead to a deeper understanding of basic device physics and the degradation mechanisms behind failure.

Kaplar, Robert James; Brock, Reinhard C.; Marinella, Matthew; King, Michael Patrick; Smith, Mark A.; Atcitty, Stanley

2011-01-01T23:59:59.000Z

485

Dynamics of a vesicle as a cell mimic: Effects of interior structure, cross-membrane transport, and interaction with filaments  

E-Print Network (OSTI)

Dynamics of a vesicle as a cell mimic: Effects of interior structure, cross-membrane transport, and interaction with filaments The biological membrane is, in essence, a thermodynamically-nonequilibrium lipid bilayer [6, 30, 34, 43, 47] with a variety of molecular motors, ion pumps, or channels residing within [19

Young, Yuan N.

486

Non-filamentated ultra-intense and ultra-short pulse fronts in three-dimensional Raman seed amplification  

SciTech Connect

Ultra-intense and ultra-short laser pulses may be generated up to the exawatt-zetawatt regime due to parametric processes in plasmas. The minimization of unwanted plasma processes leads to operational limits which are discussed here with respect to filamentation. Transverse filamentation, which originally was derived for plane waves, is being investigated for seed pulse propagation in the so called ?-pulse limit. A three-dimensional (3D) three-wave-interaction model is the basis of the present investigation. To demonstrate the applicability of the three-wave-interaction model, the 1D pulse forms are compared with those obtained from 1D particle in cell and Vlasov simulations. Although wave-breaking may occur, the kinetic simulations show that the leading pumped pulse develops a form similar to that obtained from the three-wave-interaction model. In the main part, 2D and 3D filamentation processes of (localized) pulses are investigated with the three-wave-interaction model. It is shown that the leading pulse front can stay filamentation-free, whereas the rear parts show transverse modulations.

Lehmann, G.; Spatschek, K. H. [Institut fr Theoretische Physik, Heinrich-Heine-Universitt Dsseldorf, D-40225 Dsseldorf (Germany)] [Institut fr Theoretische Physik, Heinrich-Heine-Universitt Dsseldorf, D-40225 Dsseldorf (Germany)

2014-05-15T23:59:59.000Z

487

Observations of the filamentation of high-intensity laser-produced electron beams M. S. Wei,1  

E-Print Network (OSTI)

be necessary for actual ignition experiments, the required laser needs to have energies of tens of kObservations of the filamentation of high-intensity laser-produced electron beams M. S. Wei,1 F. N Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 OQX, United Kingdom 5

Strathclyde, University of

488

Quantum Hasimoto transformation and nonlinear waves on a superfluid vortex filament under the quantum local induction approximation  

E-Print Network (OSTI)

The Hasimoto transformation between the classical LIA (local induction approximation, a model approximating the motion of a thin vortex filament) and the nonlinear Schr\\"odinger equation (NLS) has proven very useful in the past, since it allows one to construct new solutions to the LIA once a solution to the NLS is known. In the present paper, the quantum form of the LIA (which includes mutual friction effects) is put into correspondence with a type of complex nonlinear dispersive partial differential equation (PDE) with cubic nonlinearity (similar in form to a Ginsburg-Landau equation, with additional nonlinear terms). Transforming the quantum LIA in such a way enables one to obtain quantum vortex filament solutions once solutions to this dispersive PDE are known. From our quantum Hasimoto transformation, we determine the form and behavior of Stokes waves and a standing 1-soliton solution under normal and binormal friction effects. The soliton solution on a quantum vortex filament is a natural generalization of the classical 1-soliton solution constructed mathematically by Hasimoto (which motivated subsequent real-world experiments). The quantum Hasimoto transformation is useful when normal fluid velocity is relatively weak, so for the case where the normal fluid velocity is dominant we resort to other approaches. We consider the dynamics of the tangent vector to the vortex filament directly from the quantum LIA, and this approach, while less elegant than the quantum Hasimoto transformation, enables us to study waves primarily driven by the normal fluid velocity.

Robert A. Van Gorder

2014-11-19T23:59:59.000Z

489

Surface hardening of Fe-based alloy powders by Nd:YAG laser cladding followed by electrospark deposition with WC-Co cemented carbide  

Science Journals Connector (OSTI)

This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by integrating laser cladding and the electrospark deposition processes. Specimens of...

Jiansheng Wang; Huimin Meng; Hongying Yu; Zishuan Fan; Dongbai Sun

2010-08-01T23:59:59.000Z

490

Filamentation of magnetosonic wave and generation of magnetic turbulence in laser plasma interaction  

SciTech Connect

This paper presents a theoretical model for the magnetic turbulence in laser plasma interaction due to the nonlinear coupling of magnetosonic wave with ion acoustic wave in overdense plasma. For this study, dynamical equations of magnetosonic waves and the ion acoustic waves have been developed in the presence of ponderomotive force due to the pump magnetosonic wave. Slowly converging and diverging behavior has been studied semi-analytically, this results in the formation of filaments of the magnetosonic wave. Numerical simulation has also been carried out to study nonlinear stage. From the results, it has been found that the localized structures become quite complex in nature. Further, power spectrum has been studied. Results show that the spectral index follows (?k{sup ?2.0}) scaling at smaller scale. Relevance of the present investigation has been shown with the experimental observation.

Modi, K. V., E-mail: kvmodi.iitd@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Mechanical Engineering Department, Government Engineering College Valsad, Gujarat 396001 (India); Tiwary, Prem Pyari, E-mail: prempyari@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Department of Physics and Computer Science, Dayal Bagh Educational Institute (Deemed University), Dayal Bagh, Agra 282005 (India); Singh, Ram Kishor, E-mail: ram007kishor@gmail.com; Sharma, R. P., E-mail: rpsharma@ces.iitd.ac.in [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Satsangi, V. R. [Department of Physics and Computer Science, Dayal Bagh Educational Institute (Deemed University), Dayal Bagh, Agra 282005 (India)

2014-10-15T23:59:59.000Z

491

Thick-to-Thin Filament Surface Distance Modulates Cross-Bridge Kinetics in Drosophila Flight Muscle  

SciTech Connect

The demembranated (skinned) muscle fiber preparation is widely used to investigate muscle contraction because the intracellular ionic conditions can be precisely controlled. However, plasma membrane removal results in a loss of osmotic regulation, causing abnormal hydration of the myofilament lattice and its proteins. We investigated the structural and functional consequences of varied myofilament lattice spacing and protein hydration on cross-bridge rates of force development and detachment in Drosophila melanogaster indirect flight muscle, using x-ray diffraction to compare the lattice spacing of dissected, osmotically compressed skinned fibers to native muscle fibers in living flies. Osmolytes of different sizes and exclusion properties (Dextran T-500 and T-10) were used to differentially alter lattice spacing and protein hydration. At in vivo lattice spacing, cross-bridge attachment time (t{sub on}) increased with higher osmotic pressures, consistent with a reduced cross-bridge detachment rate as myofilament protein hydration decreased. In contrast, in the swollen lattice, t{sub on} decreased with higher osmotic pressures. These divergent responses were reconciled using a structural model that predicts t{sub on} varies inversely with thick-to-thin filament surface distance, suggesting that cross-bridge rates of force development and detachment are modulated more by myofilament lattice geometry than protein hydration. Generalizing these findings, our results suggest that cross-bridge cycling rates slow as thick-to-thin filament surface distance decreases with sarcomere lengthening, and likewise, cross-bridge cycling rates increase during sarcomere shortening. Together, these structural changes may provide a mechanism for altering cross-bridge performance throughout a contraction-relaxation cycle.

Tanner, Bertrand C.W.; Farman, Gerrie P.; Irving, Thomas C.; Maughan, David W.; Palmer, Bradley M.; Miller, Mark S. (IIT); (Vermont); (BU)

2012-09-19T23:59:59.000Z

492

Design and testing of a boron carbide capsule for spectral-tailoring in mixed-spectrum reactors  

SciTech Connect

A boron carbide capsule has been designed and used for spectral-tailoring experiments at the TRIGA reactor at Washington State Univ.. Irradiations were conducted in pulsed mode and in continuous operation for up to 4 h. A cadmium cover was used to reduce thermal heating. The neutron spectrum calculated with the Monte Carlo N-particle transport code was found to be in good agreement with reactor dosimetry measurements using the STAY'SL computer code. The neutron spectrum resembles that of a fast reactor. The design of a capsule using boron carbide fully enriched in {sup 10}B shows that it is possible to produce a neutron spectrum similar to that of {sup 235}U fission. (authors)

Greenwood, L.R.; Wittman, R. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Pierson, B.P. [Univ. of Michigan, Ann Arbor, MI 48109 (United States); Metz, L.A.; Payne, R.; Finn, E.C.; Friese, J.I. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

2011-07-01T23:59:59.000Z

493

Electric Discharge Sintering and Joining of Tungsten Carbide--Cobalt Composite with High-Speed Steel Substrate  

SciTech Connect

Simultaneous electro discharge sintering of high strength structure of tungsten carbide-cobalt composite and connection it with high-speed steel substrate is investigated and suitable operating parameters are defined. Tungsten carbide-cobalt and high-speed steel joining was produced by the method of high voltage electrical discharge together with application of mechanical pressure to powder compact. It was found that the density and hardness of composite material reach its maximum values at certain magnitudes of applied pressure and high voltage electrical discharge parameters. We show that there is an upper level for the discharge voltage beyond which the powder of composite material disintegrates like an exploding wire. Due to our results it is possible to determine optimal parameters for simultaneous electro discharge sintering of WC-Co and bonding it with high-speed steel substrate.

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

2011-01-17T23:59:59.000Z

494

SILICON CARBIDE MICRO-DEVICES FOR COMBUSTION GAS SENSING UNDER HARSH CONDITIONS  

SciTech Connect

A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen containing species in chemically reactive, high temperature environments. For these capacitive sensors we have determined that the optimum sensor operating point in terms of sensor lifetime and response time is at midgap. Detailed measurements of the oxide leakage current as a function of temperature were performed to investigate the high temperature reliability of the devices. In addition, robust metallization and electrical contacting techniques have been developed for device operation at elevated temperatures. To characterize the time response of the sensor responses in the millisecond range, a conceptually new apparatus has been built. Using laser induced fluorescence imaging techniques we have shown that the gas underneath the sensor can be completely exchanged with a time constant under 1 millisecond. Ultrahigh vacuum studies of the surface chemistry of the platinum gate have shown that sensor deactivation by adsorbed sulfur is a possible problem. Investigations on the chemical removal of sulfur by catalytic oxidation or reduction are continuing.

Ruby N. Ghosh; Peter Tobias; Roger G. Tobin

2004-10-01T23:59:59.000Z

495

Heavy Element Abundances in Presolar Silicon Carbide Grains from Low-Metallicity AGB Stars  

E-Print Network (OSTI)

Primitive meteorites contain small amounts of presolar minerals that formed in the winds of evolved stars or in the ejecta of stellar explosions. Silicon carbide is the best studied presolar mineral. Based on its isotopic compositions it was divided into distinct populations that have different origins: Most abundant are the mainstream grains which are believed to come from 1.5-3 Msun AGB stars of roughly solar metallicitiy. The rare Y and Z grains are likely to come from 1.5-3 Msun AGB stars as well, but with subsolar metallicities (0.3-0.5x solar). Here we report on C and Si isotope and trace element (Zr, Ba) studies of individual, submicrometer-sized SiC grains. The most striking results are: (1) Zr and Ba concentrations are higher in Y and Z grains than in mainstream grains, with enrichments relative to Si and solar of up to 70x (Zr) and 170x (Ba), respectively. (2) For the Y and Z grains there is a positive correlation between Ba concentrations and amount of s-process Si. This correlation is well explain...

Hoppe, P; Vollmer, C; Groener, E; Heck, P R; Gallino, R; Amari, S; 10.1071/AS08033

2009-01-01T23:59:59.000Z

496

Recent advances and issues in development of silicon carbide composites for fusion applications  

SciTech Connect

Radiation-resistant advanced silicon carbide composites (SiC/SiC) have been developed as a promising candidate of the high-temperature operating advanced fusion DEMO reactor. With the completion of the proof-of-principle phase in development of nuclear-grade SiC/SiC, the R&D on SiC/SiC is shifting toward the more pragmatic phase, i.e., industrialization of component manufactures and data-basing. In this paper, recent advances and issues in 1) development of component fabrication technology including joining and functional coating, e.g., a tungsten overcoat as a plasma facing barrier, 2) recent updates in characterization of non-irradiated properties, e.g., strength anisotropy and chemical compatibility with solid lithium-based ceramics and lead-lithium liquid metal breeders, and 3) irradiation effects were specifically reviewed. Importantly high-temperature neutron irradiation effects on microstructural evolution, thermal and electrical conductivities and mechanical properties including the fiber/matrix interfacial strength were specified under various irradiation conditions, indicating seemingly very minor influence on the composite performance in the design tempera