| 摘要 |
PROBLEM TO BE SOLVED: To obtain a silicon nitride sintered compact in which fine particles of β-type silicon nitride are present at gaps in columnar crystal of α-type silicon nitride and which has high strength and excellent fracture toughness by adding a compound of a high melting point metal element, and to provide a method of producing the silicon nitride. SOLUTION: When the length of the longest particle in columnar particles 12 of the silicon nitride, having different lengths is defined as Lmax, and the length of the shortest particle is defined as Lmin, the value of Lmax/Lmin is >=20, and the value of Lmin is <=1 μm. Further, particles 13 of iron silicide and fine particles 14 of at least one high melting point metal element selected from Mo, Ta and W and/or at least one compound of the high melting point metal element are uniformly dispersed in the columnar particles 12 of the silicon nitride. The sizes of the particles 14 of the high melting point metal element and/or an oxide, a nitride or a silicide of the high melting point metal element are <=10 μm. |
