反应烧结制备Si3N4/SiC复相陶瓷及其力学性能研究

以两种不同配比Y₂O₃/Al₂O₃ (A, 2:3; B, 3:1, 总量15 wt%)为烧结助剂, 通过添加不同质量分数的SiC粉体,反应烧结制备了高强度的氮化硅/碳化硅复相陶瓷。并对材料的相组成、相对密度、显微结构和力学性能进行了分析。结果表明: 在1700℃保温2 h情况下, 烧结助剂A 与B对应的样品中α-Si₃N₄相全部转化为β-Si₃N₄; 添加5wt% SiC, 烧结助剂A对应样品的相对密度达到最大值94.8%, 且抗弯强度为521.8 MPa, 相对于不添加SiC样品的抗弯强度(338.7 MPa)提高了约54.1%。SiC能有效改善氮化硅基陶瓷力学性能, 且Si₃N₄/SiC复相陶瓷断裂以沿晶断裂方式为主。

Mechanical Properties of Reaction-bonded Si3N4/SiC Composite Ceramics

With Y₂O₃:Al₂O₃ (A 2:3; B 3:1 total amount 15wt%) as sintering additives and SiC as the second phase, high flexural strength Si₃N₄/SiC composite ceramics were prepared via nitridation of Si powder. The phase composition, relative density, microstructure as well as mechanical properties were investigated. The experimental results showed that the α→β-Si₃N₄ phase transformation could be completed at 1700℃ for 2 h with sintering additives A or B. With the sintering additive A and 5wt% SiC addition, the maximum relative density of 94.8% and maximum flexural strength of 521.8 MPa were obtained for the Si₃N₄/SiC composite ceramics. As compared with the specimen without SiC addition which flexural strength was 338.7 MPa, flexural strength of the above mentioned Si₃N₄/SiC composite ceramics was improved by 54.1%. SiC powder can effectively improve the mechanical properties of the specimen and the fracture of Si₃N₄/SiC composite ceramics followed the typical intergranular fractural mode.