US 6,982,070 B2
Process for synthesizing spinel type silicon nitride powders
Toshimori Sekine, Ibaraki (Japan); Hongliang He, Ibaraki (Japan); and Takamichi Kobayashi, Ibaraki (Japan)
Assigned to National Institute for Materials Science, Ibaraki (Japan)
Filed on Mar. 29, 2002, as Appl. No. 10/108,379.
Prior Publication US 2003/0186800 A1, Oct. 02, 2003
This patent is subject to a terminal disclaimer.
Int. Cl. C01B 21/68 (2006.01)
U.S. Cl. 423—344 2 Claims
 
1. A process for synthesizing spinel type silicon nitride powders of a high pressure phase by stress-pressing low-pressure phase silicon nitride powders with shock waves, comprising:
mixing raw powders having a particle size of 10 μm or less of α-, β- or amorphous silicon nitride, each of which is a low pressure phase, with non-nitrified metal powders at a ratio of 50 weight % or more, to form a powder mixture consisting of α-, β-, or amorphous silicon nitride and metal powders,
forming a compact with porosity of 50% or less and 10% or more by pressing the powder mixture,
subjecting said compact to shock wave compression treatment at a pressure of 20 GPa or more, and
removing non-nitrified metal powders to recover the spinel type silicon nitride powders.