| 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 chromium carbide. 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.% chromium carbide powder having 1.5-10mu average particle diameter is formed and calcined to afford the aimed calcined compact. If the average particle diameter of the silicon nitride powder to be used exceeds 5 P, improvement in toughness is not recognized. The preferred average particle diameter is <=3mu, especially <=1mu. If the amount of the calcining assistant is <0.2vol.%, calcining effects are hardly obtained. If the amount exceeds 5vol.%, strength is deteriorated. MgO, MgAl2O4, MgSiO4, MgSiO3, Mg(OH)2, cordierite, etc., are cited as the calcining assistant used. |
