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Title: Compaction of Ceramic Microspheres, Spherical Molybdenum Powder and Other Materials to 3 GPa

Abstract

Pressure-volume relationships were measured at room temperature for eight granular materials and one specimen of epoxy foam. The granular materials included hollow ceramic microspheres, spherical molybdenum powder, Ottawa sand, aluminum, copper, titanium and silicon carbide powders and glassy carbon spheres. Measurements were made to 0.9 GPa in a liquid medium press for all of the granular materials and to 3 GPa in a solid medium press for the ceramic microspheres and molybdenum powder. A single specimen of epoxy foam was compressed to 30 MPa in the liquid medium press. Bulk moduli were calculated as a function of pressure for the ceramic microspheres, the molybdenum powder and three other granular materials. The energy expended in compacting the granular materials was determined by numerically integrating pressure-volume curves. More energy was expended per unit volume in compacting the molybdenum powder to 1 GPa than for the other materials, but compaction of the ceramic microspheres required more energy per gram due to their very low initial density. The merge pressure, the pressure at which all porosity is removed, was estimated for each material by plotting porosity against pressure on a semi-log plot. The pressure-volume curves were then extrapolated to the predicted merge pressures andmore » numerically integrated to estimate the energy required to reach full density for each material. The results suggest that the glassy carbon spheres and the ceramic microspheres would require more energy than the other materials to attain full density.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
899097
Report Number(s):
UCRL-TR-219532
TRN: US0703545
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CARBON; CERAMICS; COMPACTING; COPPER; GRANULAR MATERIALS; MICROSPHERES; MOLYBDENUM; POROSITY; SAND; SILICON CARBIDES; TITANIUM

Citation Formats

Carlson, S R, Bonner, B P, Ryerson, F J, and Hart, M M. Compaction of Ceramic Microspheres, Spherical Molybdenum Powder and Other Materials to 3 GPa. United States: N. p., 2006. Web. doi:10.2172/899097.
Carlson, S R, Bonner, B P, Ryerson, F J, & Hart, M M. Compaction of Ceramic Microspheres, Spherical Molybdenum Powder and Other Materials to 3 GPa. United States. doi:10.2172/899097.
Carlson, S R, Bonner, B P, Ryerson, F J, and Hart, M M. Fri . "Compaction of Ceramic Microspheres, Spherical Molybdenum Powder and Other Materials to 3 GPa". United States. doi:10.2172/899097. https://www.osti.gov/servlets/purl/899097.
@article{osti_899097,
title = {Compaction of Ceramic Microspheres, Spherical Molybdenum Powder and Other Materials to 3 GPa},
author = {Carlson, S R and Bonner, B P and Ryerson, F J and Hart, M M},
abstractNote = {Pressure-volume relationships were measured at room temperature for eight granular materials and one specimen of epoxy foam. The granular materials included hollow ceramic microspheres, spherical molybdenum powder, Ottawa sand, aluminum, copper, titanium and silicon carbide powders and glassy carbon spheres. Measurements were made to 0.9 GPa in a liquid medium press for all of the granular materials and to 3 GPa in a solid medium press for the ceramic microspheres and molybdenum powder. A single specimen of epoxy foam was compressed to 30 MPa in the liquid medium press. Bulk moduli were calculated as a function of pressure for the ceramic microspheres, the molybdenum powder and three other granular materials. The energy expended in compacting the granular materials was determined by numerically integrating pressure-volume curves. More energy was expended per unit volume in compacting the molybdenum powder to 1 GPa than for the other materials, but compaction of the ceramic microspheres required more energy per gram due to their very low initial density. The merge pressure, the pressure at which all porosity is removed, was estimated for each material by plotting porosity against pressure on a semi-log plot. The pressure-volume curves were then extrapolated to the predicted merge pressures and numerically integrated to estimate the energy required to reach full density for each material. The results suggest that the glassy carbon spheres and the ceramic microspheres would require more energy than the other materials to attain full density.},
doi = {10.2172/899097},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jan 27 00:00:00 EST 2006},
month = {Fri Jan 27 00:00:00 EST 2006}
}

Technical Report:

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  • Pressure-volume relationships were measured for unexpanded Expancel microspheres, epoxy foam and one specimen of crushed foam powder. The specimens were jacketed in tin canisters and compressed at ambient temperature and low strain rates to 3 GPa in a solid medium press. Pressures were corrected for friction, and specimen volumes were calculated relative to a nickel standard. The pressure-volume curves for each material show large volume reductions at pressures below 0.1 GPa. The curves stiffen sharply at or near full density. Relatively little volume reduction is observed above 0.1 GPa, and most is recovered on unloading. The energy expended in compressingmore » the materials to 3 GPa and the energy recovered on unloading were determined by numerically integrating the pressure-volume curves. The net energy, which includes absorbed energy, was found to be small. Compressibilities and bulk moduli were determined from the slopes of the pressure-volume curves. The Expancel bulk modulus above 0.1 GPa was found to be similar to that of isopentane. The pressure-volume data were fit to a model from the ceramics literature (Kawakita and Ludde, 1970). The model fits provided estimates of the initial specimen porosities and room pressure bulk moduli.« less
  • A structural compaction model is used to correlate NSWC quasi-static compaction data on porous beds of six (6) different materials, i.e., four (4) ball powders, melamine, and Teflon. Initial densities of the porous beds ranged from 44 percent solid theoretical maximum density (TMD) to 70 percent TMD. Maximum compacted densities were about 90 percent TMD except for Teflon which was compacted to approximately 98 percent TMD. Pressures calculated by the model, plotted as a function of percent TMD, agree well with the NSWC data.
  • With the exception of elevated-temperature tests, the evaluation of dispersion hardening agents added to molybdenum by dry blending was completed. Of the three refractory oxides added in various concentrations by weight TiO/sub 2/ raised the recrystallization temperature by 100/sup o/F over that obtained with ZrO/sub 2 and Al2/O/sub 3/ additions. These latter additions apparently had no effect on raising the recrystallization temperature above that of unalloyed molybdenum. Icreasing percentages of oxide additions had an inverse effect on room temperature formability of as-rolled sheet. A stress-relief anneal improved formability. Wet-doping methods (22 variations) of adding dispersion hardening agents are in processmore » based on the purest raw material paramolybdate. In addition to the three additives mentioned previously, ThO/sub 2/, Cr/sub 2/O/sub 3/, Ti, and ZrO/sub 2/ + Ti are under investigation. In the development of process specifications, the effect of variations in sintered density on edge cracldng in sheet was illustrated. The sintered density of the slab prior to rolling apparently had no effect on the control of finished sheet properties. The finished sheet properties were a result of the rolling schedule. The trend reported previously, that sintered density increased with increasing slab size, was shown to exist. However, since the variations were small and with those experienced from lot to lot, the study was discontin ued. Further work was done on unalloyed molybdenum in optimizing the rolling procedure and setting up test equipment for material evaluation. In the powder-rolling feasibility study, some 5- to 10-mil molybdenum sheet was produced which had room-temperature propertles comparable to sheet produced by standard techniques. Investigation continued on finding an optimum metal powder, proper rolling speeds and powder flow, sintering, and rerolling. Further attempts were made at producing a Mo-0.5% Ti alloy by adding TiHi/sub 2//sub ./ (auth)« less
  • Sound high density cylinders of graphite were made by cold compacting finely ground artificial graphite at pressures of 60 tsi. Cylinders could be made only if the graphite used was 50% finer than 10 microns and freshly ground. Storage of the powder in moist atmospheres or heating of the powder reduced its compacting properties. Uranium and thorium metal powders and uranium and thorium oxide up to 60 wt % equivalent metals were added to the graphite and sound cylinders made from the mixtures. The compacts were heated to high temperatures (up to 2800 deg C) to convert the metals ormore » oxides to carbides which rapidly hydrolyze in moist air. Measurements of compressive strength and density changes and investigation of the properties of the compacts of thermal cycling were made. Compacts made from metal powders are considered satisfactory for use as fuel for a High Temperature Gas Cooled reactor system provided their irradiation stability is satisfactory. (auth)« less