Low temperature fabrication from nano-size ceramic powders. Final report
- National Inst. of Standards and Technology (MSEL), Gaithersburg, MD (United States). Ceramics Div.
- Rutgers Univ., Piscataway, NJ (United States)
- AFOSR, Washington, DC (United States)
Understanding of compaction and rheology of ceramic powders is needed for production of defect-free greenware. High pressure and lubricating media (liq. N{sub 2}, pentane) were used for increased green body density. High green densities could be achieved with nanosize Si nitride and {gamma} alumina. A pressure/temperature system was built which uses an Instron screw-driven press and a piston/cylinder die. Max random packing density of 57 {plus_minus} 2% theoretical was achieved for dry compaction of Si nitride at 2.5 GPa and RT; compaction under liq. N{sub 2} gave 64 {plus_minus} 2%. Dry compaction of alumina was 64% theoretical at 2.5 GPa. Pressureless sintering of Si nitride green compacts did not result in further densification. Hot pressing increased the hardness. In alumina, increased compaction pressure enhances the {gamma}-{alpha} transition and increases the densification upon heat treatment. It is difficult to obtain dense material without coarsened pore/grain microstructure. SANS showed alumina results similar to those found for materials made by inert-gas-condensation. Theoretical studies were also made to model the compaction process. Future studies are outlined.
- Research Organization:
- Oak Ridge National Lab., TN (United States); National Inst. of Standards and Technology (MSEL), Gaithersburg, MD (United States). Ceramics Div.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 54245
- Report Number(s):
- ORNL/SUB--92-22041/02; ON: DE95010995
- Country of Publication:
- United States
- Language:
- English
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