| 摘要 |
PURPOSE:To obtain a silicon nitride-based sintered compact having excellent dimensional accuracy and, simultaneously, excellent in room-temperature strength and fracture toughness. CONSTITUTION:A formed body having a composition composed of 30-80wt.% of silicon nitride, 19.5-69.5wt.% of silicon and 0.5-30wt.% of one or more kinds of oxides of group IIIa elements in the Periodic Table is subjected to nitriding treatment in a nitrogen-containing atmosphere by nitriding of the silicon so that beta-silicon nitride content in total silicon nitride may become 15% to 50%, and further, the treated formed body is baked in a non-oxidizing atmosphere containing nitrogen to produce needle-like silicon nitride crystals. |
