Silicon nitride sintered body and method for producing same

摘要

There is obtained, by mixing oxide raw material powders, compacting the mixture and sintering the compact, a silicon nitride sintered body mainly composed of silicon nitride and having a grain boundary phase wherein crystals represented by Yb2Si2O7 and a Zr3Yb4O12 are present in the grain boundary phase and molar ratio ZrO2/Yb2O3 in terms of ZrO2 and Yb2O3 is 2/98 to 75/25 and the total amount of ZrO2 and Yb2O3 is 1-40% by weight of the sintered body.