High-packing silicon nitride powder and method for making

U.S. Patent Number: 5348919

Abstract: High-packing silicon nitride powder is prepared by reacting metallic silicon powder having a mean particle size of 1 to 10 .mu.m and a purity of at least 99% directly with nitrogen for forming silicon nitride powder, milling the silicon nitride powder in a dry attritor until the tap density exceeds 0.9 g/cm.sup.3 and the content of particles having an aspect ratio of up to 3 exceeds 95% by weight, and further milling the silicon nitride powder in a wet attritor for finely dividing coarse particles having a particle size of at least 2 .mu.m. The silicon nitride powder has a tap density of at least 0.9 g/cm.sup.3 and a mean particle size of 0.4 to 0.6 .mu.m and contains at least 95% by weight of particles having an aspect ratio of up to 3 and up to 5% by weight of coarse particles having a particle size of at least 2 .mu.m. The powder is moldable into a high density compact, from which a sintered part having improved dimensional precision and strength is obtained.

Inventors: Kuwabara; Haruyoshi (Gunma, JP), Otsuka; Akio (Gunma, JP), Maki; Yasuyuki (Annaka, JP), Kashida; Meguru (Annaka, JP)

Assignee: Shin-Etsu Chemical Co., Ltd. (Tokyo, JP)

Application Number: 08/077,425

Issued: 1994-09-20

Expired: 2006-09-20

Classes: 501/97.1 ; 423/344; 423/349; 423/409; 501/154; 501/94

Field of search: 501/94,96,97,154 264/65 423/324,344,349,351,353,385,406,409

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