High-temperature characterization of self-reinforced Si3N4 with additives Y2O3 and La2O3

High-temperature strength and fracture toughness ,oxidation behavior ,and thermal shock of the SR Si3N4 with Y2O3 and La2O3 as complex additives are investigated. The research results show that the strength does not decrease until 1400 degrees C; the fracture toughness, while, increases with temperature rising and presents peak value at 1350 degrees C. The oxidation behavior obeys parabolic law, and the oxidation procedure is mainly controlled by diffusion of additive ions. The high oxidation resistance of this material is primary due to the presence of refractory Y3+ and La3+ at intergranular glass phase. The thermal shock experiments show that the damage of strength is far larger than that of fracture toughness.