| 摘要 |
PROBLEM TO BE SOLVED: To provide a silicon nitride sintered compact which exhibits sufficient wear resistance at its surface after being ground or polished and which is preferably worked when being subjected to working such as grinding and polishing and enables the enhancement of the production efficiency. SOLUTION: A gradient layer having a thickness of 100 to 500 μm of the components of a sintering aid, in which the content of at least one of cation elements being components of the sintering aid is nearly continuously decreased in the depth direction from the surface of a sintered body, is formed on the surface layer part of a silicon nitride-based sintered compact having such a texture that silicon nitride-based main phases are bound with grain boundary phases mainly comprising the components of the sintering aid. In the case that such gradient of the components of the sintering aid is formed, the amount of the components of the sintering aid is increased in only the surface layer part to be eliminated of the sintered compact, thereby workability of the sintered compact is improved, and the efficiency in working and finishing processes such as grinding or polishing is markedly enhanced. Further, so long as the surface layer part is removed, an internal layer part which is low in volume ratio of the components of the sintering aid, namely, the grain boundary phases and more hard than the surface layer part is exposed to the surface, and thereby the wear resistance is sufficiently secured. |
