Si_3N_4-MgO-Al_2O_3的SPS制备及其力学性能

Preparation and Mechanical Property of Si_3N_4-MgO-Al_2O_3 by Spark Plasma Sintering Technique

利用氧化镁（MgO）和氧化铝（Al2O3）作为烧结助剂，采用放电等离子烧结（SPS）方法制备α-Si3N4陶瓷材料。讨论了SPS方法制备氮化硅材料的烧结行为和烧结机理，分析了烧结助剂添加量和烧结温度等影响因素与材料致密度的关系，利用XRD分析了样品的物相组成，SEM观察了样品断口的显微结构，并且测试了样品的力学抗弯强度。结果表明：当烧结温度为1300～1500℃，烧结助剂含量为6％-10％时，可以制备出致密度变化范围为64％～96％的α-Si3N4陶瓷材料；当烧结助剂含量为10％时，材料在1400℃即可烧结致密，致密度可达到95％以上。烧结机理为SPS低温液相烧结。材料的力学强度为50-403MPa，并且与密度关系密切。

In the present study, α-SiaN4 was prepared by using spark plasma sintering （SPS） technique with MgO and Al2O3 as the sintering additives. The SPS sintering behavior and mechanism were discussed. The relationship between the content of sintering additives, sintering temperature and relative densities of the samples was analyzed. The phase composition was analyzed by XRD, the microstructure of the fracture surface was observed by SEM and the bending strength was tested by three-point method. The results show that when the sintering temperature is 1300-1500℃ and the content of sintering additives is 6%-10%, the relative density of sintered samples is between 64% and 96% ; when the sintering temperature reaches 1400℃ and the content of sintei＇ing additives is 10%, the samples could be fully dense sintered with the relative density up to 95%. The sintering mechanism is found to be liquid phase sintering. The bending strength of the sintered samples is 50 -403MPa and had close relation with the relative density.