籽晶添加对氮化硅陶瓷显微结构与力学性能的影响

Microstructure and Mechanical Performance of Silicon Nitride Ceramics with Seeds Addition

以不同配比的Y2O3-Al2O3为烧结助剂,通过添加3wt%的单分散β-Si3N4籽晶,采用气压烧结制备了氮化硅陶瓷,并对所得材料的相组成、密度、室温和高温力学性能及显微结构进行了研究.结果表明:不同烧结助剂配比的α-Si3N4粉体在1800℃保温2 h即全部转化为β-Si3N4,且各烧结体的相对密度都达到了97%以上.在6wt%Y2O3和4.5wt%Al2O3为烧结助剂时,添加3wt%籽晶的样品其室温强度和1200℃高温强度分别提高了20%和16%,断裂韧性提高了8%.

With Y2O3：Al2O3 of different weight ratios as sintering additives and 3wt% β-Si3N4 seeds addition,silicon nitride ceramics were prepared by gas pressure sintering.The phase composition,density,microstructure,room temperature as well as elevated temperature mechanical properties were investigated.The experimental results indicated that the α→β phase transformation of silicon nitride would be finished at 1800℃ for 2 h,and the densities of all specimens were over 97% of theoretical density.Compared with the specimen without seeds addition,the room temperature bending strength,the elevated temperature flexural strength at 1200℃ and the fracture toughness of the specimen with 6wt%Y2O3-4.5wt%Al2O3and 3wt% β-Si3N4seeds addition can be improved by 20%,16% and 8%,respectively.