PRODUCTION OF SILICON NITRIDE-BASED SINTERED BODY

摘要

PURPOSE:To secure original strength in any silicon nitride-based sintered body by setting the SiO atmosphere as the atmosphere in which the sintered body made of silicon nitride and a sintering auxiliary is heat-treated at the specified temp. and forming the specified amount of silicate glass on the surface of the sintered body. CONSTITUTION:A silicon nitride-based sintered body made of silicon nitride and a sintering auxiliary is heat-treated at 1300-1900 deg.C in the nonoxidative atmosphere contg. SiO. Thereby gaseous SiO is condensed into SiO2 on the surface of the sintered body at a time of high temp. or in a cooling stage. Simultaneously silicate glass is formed on the surface of the sintered body while allowing one part thereof to react with the sintering auxiliary component contained in the sintered body. At this time, weight increase of the sintered body after treatment is regulated to 0.2-7mg/cm<2> in order to form this silicate glass at proper thickness. The surface can be modified and original strength held by the sintered body can be sufficiently secured by this method regardless of the sintering auxiliary and the sintering conditions of the sintered body.