| 摘要 |
PURPOSE:To obtain a heat-resistant sintered material having excellent high- temperature strength by mixing alpha-silicon nitride as a main component with yttrium oxide, aluminum oxide, etc., at specific ratios and sintering the obtained powdery raw material in nitrogen atmosphere to form a crystal phase of a high-melting compound in the grain boundary. CONSTITUTION:alpha-Silicon nitride used as a main component is mixed with 1-10mol% of yttrium oxide powder and 1-10mol% of powder selected from aluminum oxide, neodymium oxide, lanthanum oxide and cerium oxide. The mixture is further incorporated with <=0.5mol% of metal oxide, metal nitride or metal carbide. The mixed powdery raw material is sintered in an HIP oven in nitrogen atmosphere of 100-300kgf/cm<2> pressure at 1700-2000 deg.C for 1-20hr and cooled to 1300 deg.C at a cooling rate of about 5-10 deg.C/min to obtain a sintered material containing the main phase consisting of beta-silicon nitride crystal and the grain boundary phase of the main phase composed mainly of crystal phase containing an element selected from yttrium, aluminum, neodymium, etc. |
