SUPERPLASTIC SILICON NITRIDE SINTERED COMPACT AND ITS PRODUCTION

摘要

PURPOSE: To produce a superplastic silicon nitride sintered compact capable of providing a highly tough sintered compact by the superplastic working. CONSTITUTION: This superplastic silicon nitride sintered compact is constituted of >=85 and <=98vol.% β type silicon nitride grains and >=2 and <=15vol.% grain boundary phase and has >=95% relative density. The silicon nitride grains comprise >=93 and <=99.5wt.% matrix grains having <=0.3μm average grain diameter and >=0.5 and <=7wt.% nuclear grains having the average grain diameter of >=2 and <=7 times the average grain diameter of the matrix grains.