Silicon nitride sintered body and process for producing the same

Details Silicon nitride sintered body and process for producing the same Silicon nitride sintered body and process for producing the same

1991-12-18

1992-12-22

Group, Karl

Compositions: ceramic

Ceramic compositions

Refractory

501 98, 264 65, C04B 3558

Patent

active

051734583

ABSTRACT:
Disclosed is a silicon nitride sintered body produced by subjecting a green compact of a mixed powder composed of 1) a silicon nitride powder having a percentage .alpha. crystallization of 93% or more and a mean grain diameter of 0.7 .mu.m or less and 2) 5 to 15% by weight in total of a first sintering aid selected from among rare earth element, yttrium oxide and lanthanide oxides and a second sintering aid consisting of aluminum oxide or nitride and at least one selected from among oxides and nitrides of Mg, Ca and Li, to primary sintering in a nitrogen gas atmosphere under a pressure of 1.1 atm or less at 1500.degree. to 1700.degree. C.; and subjecting the sintered body to secondary sintering in a nitrogen gas atmosphere under a pressure of 10 atm or more at the primary sintering temperature or below, thereby giving a sintered body wherein the relative density of the sintered body is 99% or more and the precipitation ratio of an .alpha.-Si.sub.3 N.sub.4 (including .beta.'-sialon) crystal phase ranges from 1:3 to 1:8 in terms of the peak intensity ratio in X-ray diffraction.

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patent: 5045513 (1991-09-01), Mizuno et al.
Mitomo, "Strengthening of Silicon Nitride Ceramics", Solids Handling Processing Industry, vol. 12, No. 12 pp. 27-32 (1989).

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