| 摘要 |
PURPOSE:To obtain a silicon nitride sintered compact capable of developing the strength at low temperatures by preventing oxidation at the low temperatures while maintaining the high strength at high temperatures and a method for producing the aforementioned sintered compact. CONSTITUTION:A silicon nitride sintered compact having a grain boundary phase composed of a rare earth element (Re)-Si-O-N is heat-treated at 700-1000 deg.C in an oxidizing atmosphere and then heat-treated at 900-1350 deg.C in an inert atmosphere other than nitrogen to crystallize only the grain boundary on the surface of the sintered compact into crystals having the same X-ray diffraction pattern as that of JCPDS card No.21-1458 while directly maintaining the interior of the sintered compact as the grain boundary phase composed of the rare earth element (Re)-Si-O-N. |
