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Title: Power mixture and green body for producing silicon nitride base & articles of high fracture toughness and strength

A powder mixture and a green body for producing a silicon nitride-based article of improved fracture toughness and strength. The powder mixture includes 9a) a bimodal silicon nitride powder blend consisting essentially of about 10-30% by weight of a first silicon mitride powder of an average particle size of about 0.2 .mu.m and a surface area of about 8-12m.sup.2 g, and about 70-90% by weight of a second silicon nitride powder of an average particle size of about 0.4-0.6 .mu.m and a surface area of about 2-4 m.sup.2 /g, (b) about 10-50 percent by volume, based on the volume of the densified article, of refractory whiskers or fibers having an aspect ratio of about 3-150 and having an equivalent diameter selected to produce in the densified articel an equivalent diameter ratio of the whiskers or fibers to grains of silicon nitride of greater than 1.0, and (c) an effective amount of a suitable oxide densification aid. The green body is formed from the powder mixture, an effective amount of a suitable oxide densification aid, and an effective amount of a suitable organic binder.
Inventors:
 [1];  [2];  [2]
  1. (Marlboro, MA)
  2. (Acton, MA)
Issue Date:
OSTI Identifier:
867991
Assignee:
GTE Laboratories Incorporated (Waltham, MA) ORNL
Patent Number(s):
US 5049530
Contract Number:
AC05-84OR21400
Research Org:
LOCKHEED MARTIN ENRGY SYST INC
Country of Publication:
United States
Language:
English
Subject:
power; mixture; green; producing; silicon; nitride; base; articles; fracture; toughness; strength; powder; nitride-based; article; improved; 9a; bimodal; blend; consisting; essentially; 10-30; weight; mitride; average; particle; size; surface; 8-12m; 70-90; 4-0; 2-4; 10-50; percent; volume; based; densified; refractory; whiskers; fibers; aspect; ratio; 3-150; equivalent; diameter; selected; produce; articel; grains; effective; amount; suitable; oxide; densification; formed; organic; binder; organic binder; nitride powder; effective amount; aspect ratio; fracture toughness; silicon nitride; consisting essentially; particle size; producing silicon; average particle; powder mixture; diameter ratio; improved fracture; silicon nitride-; silicon nitride-based; nitride-based article; nitride base; /501/