| 摘要 |
PURPOSE:To improve the strength of an Si3N4 sintered body at high temp. and the static fatigue characteristics especially at >=900 deg.C by forming the grain boundary phase of the sintered body contg. Y2O3, MgO and ZrO2 mainly with a J-phase solid soln. and by specifying the relation between the amt. of the solid phase and the amt. of Y2O3. CONSTITUTION:The grain boundary phase of an Si3N4 sintered body based on Si3N4 and contg. at least Y2O3, MgO and ZrO2 is formed mainly with a J-phase solid soln. and the relation between the amt. (y) of the J-phase solid soln. at the grain boundary and the amt. (x) of Y2O3 added is allowed to satisfy an inequality 0.65x<=y<=(X+2). Extremely superior mechanical strength, oxidation resistance and static fatigue characteristics, especially static fatigue characteristics at >=900 deg.C are obtd. |
