摘要
Silicon nitride ceramics as structural materials for engines need a combination of both high strength and high fracture toughness at elevated temperatures. Several recent studies show that the rare-earth oxides additive can improve the high temperature strength of Si3N4, and the bend strength of Si3N4 with Y2O3, and La2O3 additives maintains from room temperature up to 1300℃. However, the effect of rareearth oxides on high temperature fracture toughness of Si3N4 has not yet been reported. In the present work, fracture toughness tests were performed at 20 to
