| 摘要 |
<p>Silicon nitride sintered bodies having particularly excellent strength and creep resistance at high temperature, in which a total amount of MgO and A?2O3 is more than 6% by weight and not more than 30% by weight and a weight ratio of MgO/A?2O3 is 4-19 and the remainder is mainly Si3N4 and at least one of magnesium sialon crystal represented by the general formula Mgx/2Si6-y+x/2A?y-xOyN8-y (0<x?y<8, preferably 0.9?x/y) and forsterite crystal represented by the formula Mg2SiO4 is contained as a second phase in addition to the main crystal of Si3N4, are produced by mixing a raw material powder of silicon nitride containing less than 2% by weight of oxygen with MgO and A?2O3 so that a total amount of MgO and A?2O3 is from 6% by weight to 30% by weight and a weight ratio of MgO/A?2O3 is 4-19, and firing the resulting mixture at a temperature of 1,650-1,850.degree.C in nitrogen or an inert gas atmosphere.</p> |
