Claims
- 1. A silicon nitride body having a composition consisting essentially of 2.0-2.8 weight % of Y.sub.2 O.sub.3, 0.4-1.0 weight % of Al.sub.2 O.sub.3 and balance substantially Si.sub.3 N.sub.4, the weight ratio of Y.sub.2 O.sub.3 /Al.sub.2 O.sub.3 being 2.5-7, said Si.sub.3 N.sub.4 being added as silicon nitride powder having an oxygen content of 0.8-1.1 weight %, a specific surface area of 9.varies.11 m.sup.2 /g, and metal impurity content of 200 ppm or less, said sintered body having a density of 3.0 g/cm.sup.3 or more, a structure in which the minor axes of grains are substantially 6 .mu.m or less, and a high-temperature strength of about 80 kg/mm.sup.2 or more.
- 2. The silicon nitride body of claim 1, wherein said composition consists essentially of 2.5 weight % of Y.sub.2 O.sub.3, 1.0 weight % of Al.sub.2 O.sub.3 and balance substantially Si.sub.3 N.sub.4, a weight ratio of Y.sub.2 O.sub.3 /Al.sub.2 O.sub.3 of 2.5, said Si.sub.3 N.sub.4 being added as silicon nitride powder having an oxygen content of 0.9 weight %, a specific surface area of 10 m.sup.2 /g, and a metal impurity content of 200 ppm or less, said sintered body having a density of 3.17 g/cm.sup.3, and having a structure in which the maximum value of minor axes of grains is 5.8 .mu.m.
- 3. The silicon nitride body of claim 1, wherein said composition consists essentially of 2.5 weight % of Y.sub.2 O.sub.3, 0.5 weight % of Al.sub.2 O.sub.3 and balance substantially Si.sub.3 N.sub.4, a weight ratio of Y.sub.2 O.sub.3 /Al.sub.2 O.sub.3 of 5.0, said Si.sub.3 N.sub.4 being added as silicon nitride powder having an oxygen content of 1.0 weight %, a specific surface are of 10 m.sup.2 /g, and a metal impurity content of 200 ppm or less, said sintered body having a density of 3.18 g/cm.sup.3, and having a structure in which the maximum value of minor axes of grains are 5.5 .mu.m.
- 4. A method of producing a silicon nitride sintered body having a structure in which the minor axes of grains are substantially 6 .mu.m or less, comprising the steps of:
- preparing a powder mixture consisting essentially of 2.0-2.8 weight % of Y.sub.2 O.sub.3 powder, 0.4-1.0 weight % of Al.sub.2 O.sub.3 powder and balance substantially silicon nitride powder, the weight ratio of Y.sub.2 O.sub.3 /Al.sub.2 O.sub.3 being 2.5-7, said silicon nitride powder having an oxygen content of 0.8-1.1 weight %, a specific surface area of 9-11 m.sup.2 /g, and a metal impurity content of 200 ppm or less; and
- sintering said powder mixture at a temperature of 1900.degree.-2100.degree. C. and a pressure of 5 kg/cm.sup.2 G or more in a nitrogen atmosphere, thereby producing a silicon nitride sintered body exhibiting a high-temperature strength of about 80 kg/mm.sup.2 or more.
Priority Claims (1)
Number |
Date |
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Kind |
63-211117 |
Aug 1988 |
JPX |
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CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of Ser. No. 07/398,478 filed Aug. 25, 1989, abandoned which is a continuation-in-part of copending application Ser. No. 07/393,381 filed on Aug. 14, 1989, now abandoned, entitled "SILICON NITRIDE SINTERED BODY HAVING EXCELLENT HIGH-TEMPERATURE STRENGTH AND METHOD OF PRODUCING THE SAME", the entire contents of which are hereby incorporated by reference.
US Referenced Citations (8)
Foreign Referenced Citations (5)
Number |
Date |
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0176315 |
Apr 1986 |
EPX |
0277753 |
Aug 1988 |
EPX |
49-21091 |
May 1974 |
JPX |
0185863 |
Aug 1988 |
JPX |
63-185863 |
Aug 1988 |
JPX |
Continuations (1)
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Date |
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Parent |
398478 |
Aug 1989 |
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Continuation in Parts (1)
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Number |
Date |
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393381 |
Aug 1989 |
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