| 摘要 |
PURPOSE:To relatively readily obtain a highly tough calcined compact of silicon nitride, by forming and calcining a mixed powder, consisting essentially of silicon nitride powder and containing a calcining assistant containing MgO as a component and specific dispersed particles. CONSTITUTION:A mixed powder, consisting essentially of silicon nitride powder having <=5mu average particle diameter and containing calcining assistant in an amount of 0.2-5vol.% expressed in terms of MgO and 1-50vol.% dispersed particles of one or more of nitrides, carbides of group IVa elements and solid solutions thereof having 1.5-10mu average particle diameter and >=6X10<-6>/ deg.C thermal expansion coefficient is formed and calcined to afford the aimed calcined compact. If the average particle diameter of the silicon nitride powder to be used exceeds 5mu, improvement in toughness is not recognized. The preferred average particle diameter is <=3mu, especially <=1mu. TiN, TiC, ZrN, ZrC, HfN, HfC, etc., are cited as the dispersed particles. |
