Thermal shock resistance silicon nitride sintered body and a method of manufacturing the same

摘要

PURPOSE:To obtain a silicon nitride sintered compact having strength at high temp. practically equivalent to the strength at ordinary temp. and excellent in thermal shock resistance by providing a sintered compact composed essentially of silicon nitride and compounds of rare earth elements and also forming pore aggregates of specific structure in this sintered compact. CONSTITUTION:A green compact is prepared by mixing raw materials consisting of silicon nitride powder, rare earth oxide powder, and carbide powder, and this green compact is calcined in a nitrogen atmosphere to decompose carbide, by which, in the resulting sintered compact, pores of =10mum are formed and also pore aggregates composed of the above-mentioned pores of 30-100mum diameter are formed at a rate of =10 pieces/mm2. It is preferable that a surface layer consisting of 5-100-mum silicioxide of rare earth element and silicon oxide is formed on the surface of the resulting sintered compact by subjecting this calcined compact to heat treatment at 1000-1500 deg.C in an oxygen-incorporating atmosphere since strength can be improved and also thermal shock resistance can be improved to a greater extent.