| 摘要 |
PURPOSE:To obtain a sintered material of silicon nitride having excellent flex resistance and oxidation resistance at high temperature, by specifying contents of beta-Si3N4, Sc, Yb or Dy and excess oxygen and the grain boundary phase of beta-Si3N4 and making a sintered material. CONSTITUTION:A silicon nitride sintered material which is a sintered material comprising 85-99mol.% based on three components of beta-Si3N4, 1-5mol.% calculated as oxide M2O3 of a compound of at least one element (M) of Sc, Yb, Ho and Dy and excess oxygen (O) and having the molar ratio (number of mol. calculated as SiO2 of excess oxygen/number of mol. of M2O3) of 0.5-2 and has wollastonite or YAM as main crystal of grain boundary phase of beta-Si3N4, >=45kg/mm<2> high-temperature flex resistance (four points flex resistance at 1,400 deg.C) and <=0.2mg/cm<2> increase in weight by oxidation at middle temperature (1,000 deg.CX100hr). The amount of excess oxygen in the sintered material is controlled by setting a burning condition and wollastonite or YAM crystal is preferentially formed by setting the amount of excess oxygen in the above- mentioned range. |
