| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a silicon nitride sintered compact having a practically large mechanical strength and a small coefficient of thermal expansion, and small grinding resistance. <P>SOLUTION: This silicon nitride sintered compact is mainly composed of β-Si<SB>3</SB>N<SB>4</SB>, and it contains 5-30 vol% Si<SB>2</SB>N<SB>2</SB>O (silicon oxynitride) and 1-10 vol% β-RE<SB>2</SB>Si<SB>2</SB>O<SB>7</SB>(RE is an element in the group III of the periodical table). The sintered compact keeps a strong mechanical strength due to a composition composed mainly of β-Si<SB>3</SB>N<SB>4</SB>, and has a small grinding resistance due to a composition having 5-30 vol% Si<SB>2</SB>N<SB>2</SB>O and also has a small coefficient of thermal expansion of the grain boundary layer and a small residual stress in the sintered compact due to a composition having the range of 1-10 vol% β-RE<SB>2</SB>Si<SB>2</SB>O<SB>7</SB>, and further the sintered compact exhibits excellent processability allowing a smooth grinding process and the working of high dimensional accuracy due to its small grinding force. <P>COPYRIGHT: (C)2007,JPO&INPIT |
