Rutgers, The State University of New Jersey

Shih-Chieh Liao

Bernard H Kear

William E Mayo

A hot pressing method involves the simultaneous application of high pressure (1.5-8 GPa) at a relatively low temperature (0.2-0.6 T ) High compaction pressure causes particle deformation, such that the green density increases with pressure up to a maximum at about 8 GPa. Low sintering temperature mitigates grain growth during the consolidation process. Another factor that promotes densification is the occurrence of a pressure-induced phase transformation (typically from a metastable structure to a more stable structure), accompanied by a significant reduction in free volume for example greater than about 1 to about 2 vol. %. Such transformation-assisted consolidation has been successfully applied to produce sintered oxide and non-oxide bulk nanocrystalline ceramics having a grain size less than 100 nm, starting with even finer-scale ceramic nanopowders. Under appropriate high pressure conditions, a sintered grain size can be realized that is actually smaller than the original powder particle size.

Growing community of inventors

Chung-Li, Taiwan

Shih-Chieh Liao