抄録
Room temperature transverse-rupture strength and microstructure of Si3N4-MgO compacts sintered in nitrogen were mainly investigated as a function of sintering temperature and MgO content (0-30%).
The strength reached a maximum, when compacts containing 5 -10%MgO were sintered in nitrogen of l00kPa at 1973K. The Mg2SiO4 phase as the binder of Si3N4 particles was observed to have an identical crystallographic orientation in a wide region (named as a domain). The shrinkage pore acting as a fracture source was found to lie on the domain boundaries. The result of fractography showed that, even in the compact free from defects as fracture sources, the strength would not exceed the value of about 0.9GPa.
