SILICON NITRIDE POWDER FOR PRODUCING SILICON NTRIDE-BASED SINTERED BODY, SILICON NITRIDE-BASED SINTERED BODY AND ITS PRODUCTION

摘要

PURPOSE: To obtain a silicon nitride-based sintered body having a dense texture and high fracture toughness and strength at a low sintering temperature compared with the case of using conventional β-silicon nitride powder produced by a direct nitriding process as a raw material. CONSTITUTION: This silicon nitride-based sintered body having high fracture toughness and strength can be produced by using a β-silicon nitride composed of backed powder of a nitrogen-containing silane compound and/or an amorphous silicon nitride powder, containing >=80wt.% of β-silicon nitride and 0.05-2.0wt.% (in terms of metallic element concentration) of a rare earth compound and having an average particle diameter controlled to 0.1-0.5μm and an aspect ratio controlled to <=2.5, incorporating the β-silicon nitride powder with 0.2-6wt.% of one or more kinds of oxides selected from among magnesium oxide, aluminum oxide and oxides of the group IIIa element of the periodic table, forming the mixture and baking the formed product in a nitrogen- containing inert gas atmosphere under 1-100atm at 1600-1900 deg.C until the bulk density reaches >=95wt.% of the theoretical density.