微氧化对反应烧结碳化硅结构与性能的影响（英文）

Evolution of Reaction Bonded SiC Composite by Mild Oxidation: Microstructure and Mechanical Properties

以短切碳纤维为增强体,采用注浆成型和熔融硅渗透法制备了短纤维增强反应烧结碳化硅陶瓷,研究了微氧化对反应烧结碳化硅复合材料结构与性能的影响。结果表明:1 100℃微氧化处理,使反应烧结碳化硅复合材料表面形成了致密氧化硅薄膜,表面游离硅升华,同时,短纤维体积明显增加。微氧化处理使二氧化硅薄膜晶化产生方石英相,且方石英相含量随短纤维含量的增加而减少。微氧化产生的氧化硅薄膜能弥合材料表面微缺陷,当短纤维体积分数为30%时,反应烧结碳化硅的断裂韧性增加到5.8 MPa·m^(0.5)。

Reaction bonded silicon carbide （RBSC） ceramics were prepared by a combination of slip casting and liquid siliconinfiltration, with random chopped carbon fiber as reinforcement. In this study, the influence of mild oxidation on the microstructureand mechanical properties of random chopped fiber reinforced RBSC composite has been evaluated. The results show that the mildoxidation treatment led to the formation of silica layer, the gasification of liquid silicon and the oxidation of chopped fiber. Thesiliconized fiber underwent an obvious volume expansion during oxidation compared with that of the RBSC matrix. Crystallization ofsilica occurred at 1 100 ℃ on the material surface, and the content of cristobalite phase decreased with the increase of fiber content.Due to the microstructure evolution, a maximum fracture toughness of 5.8 MPa·m^0.5 was gained at the fiber volume fraction of 30%.