Densification, Mass Loss, and Mechanical Properties of Low-Temperature Pressureless-Sintered Si3N4 with LiYO2 Additive: The Effects of Additive Content and Annealing

The effects of annealing on the residual Li content, microstructure, and mechanical properties of pressureless-sintered LiYO2-Si3N4 were investigated. The bending strength and fracture toughness of the as-fabricated specimens were fair (similar to 640 MPa, similar to 5.5MPa root m), in spite of the sintering at a low temperature (1600 degrees C). The strength, Young's modulus, and hardness were improved up to 697 MPa, 284 GPa, and 13.9 GPa, respectively, by annealing treatments. Residual Li could be reduced to 0.008 wt% by annealing at 1650 degrees C in Ar. Si3N4 could be sintered at a low temperature to give materials with a relatively low elastic modulus but reasonable strength values.