| 摘要 |
PURPOSE:To obtain a high-strength calcined body excellent in thermal shock resistance with hardly any dispersion by specifying heat-treating conditions in subjecting a calcined sialon body to oxidation treatment and increasing the strength thereof. CONSTITUTION:A calcined sialon body is heated at 1000-1300 deg.C in an atmosphere containing oxygen gas for 10-30hr, further kept at 400-500 deg.C for 1-10min in an atmosphere containing oxygen gas and then cooled at >=50 deg.C/min rate. A stable oxide film is formed on the surface of the calcined body by the above- mentioned heating. Thereby, working cracks can be blunted or closed to improve strength, simultaneously enhance thermal shock resistance and raise quenching starting temperature. Furthermore, compressive stress is left on the surface by the afore-mentioned cooling and the strength can be nearly doubled as compared with that of the untreated substance. |
