The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 28, 2002
Filed:
Nov. 19, 1999
Bernard H. Kear, Whitehouse Station, NJ (US);
Shih-Chieh Liao, Chung-Li, TW;
William E. Mayo, Edison, NJ (US);
Rutgers, The State University of New Jersey, New Brunswick, NJ (US);
Abstract
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.