Rutgers, The State University of New Jersey

William E Mayo

Bernard H Kear

Richard James Mammone

Joseph Wilder

Adam B Fineberg

Shih-Chieh Liao

Mark C Croft

Zwi Kalman

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.

High pressure and low temperature sintering of nanophase ceramic powders

Energy dispersive x-ray diffraction spectra are obtained from numerous volume elements within an object. A feature set such as a set of cepstrum coefficients is extracted from each spectrum and classified by a trained classifier such as a neural network to provide an indication of whether or not contraband such as explosives is present in the volume element. Indications for adjacent volume elements are evaluated in conjunction with one another, as by an erosion process, to suppress isolated indications and thereby suppress false alarms.

Analysis methods for energy dispersive X-ray diffraction patterns

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Edison, NJ, United States of America

William E Mayo