| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a silicon nitride-based composite ceramic which has high strength and also has excellent thermal shock resistance. <P>SOLUTION: The composite ceramic comprises a silicon nitride-based ceramic as a matrix phase and, combined therewith, boron nitride as a dispersed phase, the proportion of the boron nitride being 2.5 to 10 vol.%. When the four-point bending strength as measured at 25°C in accordance with JIS R1601 is expressed by σ<SB>i</SB>and the four-point bending strength as measured after a thermal shock is applied thereto by quenching from 800°C or higher through dropping into 25°C water by the dropping-into-water method according to JIS R1615 is expressed by σ<SB>f</SB>, then the value of σ<SB>i</SB>is 400 MPa or higher and the ratio of σ<SB>f</SB>/σ<SB>i</SB>is 0.85 or higher. <P>COPYRIGHT: (C)2011,JPO&INPIT |
