Fabrication of Highly Dense Si₃N₄ Ceramics without Additives by High Pressure Sintering

Abstract

Silicon nitride (Si₃N₄) is one of Candidate materials for the engineering caraniics which can be used at high temperatures. The mechanical strengthsof hotpressed or sintered Si₃N₄ cera.; inics containing some amount of additives, however, , are deteriorated at elevated temperatures. To improve the, high temperature strength of Si₃N₄ ceramics, an attempt to consolidate Si₃N₄ without additives was made by high pressure sintering technique. Scanning, electron mic rographs of fracture surfaces of the sintered bodies showed the bodies had finely grained and fully selfbonded microstructures. Vickers microhardness of selfbonded sintered bodies were 310N/m² at room temperature and 174 N/m² at 1200°C.