基体改性对SiC/SiC复合材料高温抗氧化性能的影响

Influence of Matrix Modification on the Oxidation Resistance of SiC/SiC Composites

采用先驱体浸渍-裂解工艺结合三种基体改性方式制备了SiC/SiC复合材料,通过形貌分析和力学性能测试,分析了基体改性对Si C/SiC复合材料高温抗氧化性能的影响。研究表明,经1200℃静态空气氧化100h后,三种基体改性的复合材料弯曲强度几乎没有下降,氧化200h后,弯曲强度保留率均可达到80%;氧化300h后,复合材料内部结构没有氧化现象,表面区域界面层的氧化程度降低。改性基体中的B元素氧化生成液相封填SiC涂层表面,延缓了SiC涂层的氧化进程,并阻止氧化介质进入复合材料内部,保护纤维和界面层,从而使SiC/SiC复合材料的长时静态高温抗氧化性能明显提高。

SiC/SiC composites were prepared by precursor infiltration and pyrolysis process combined with three matrix modification methods.The effect of matrix modification on the high temperature oxidation resistance of SiC/SiC composites was analyzed by morphology analysis and mechanical property test.The results showed that the flexural strength of the matrix-modified composites hardly decreases after 100h static oxidation at 1200℃.After 200h oxidation,the retention rates of flexural strength reached 80%.After 300h oxidation,the internal structure of the composites was not oxidized and the oxidation degree of the interface layer in the surface area decreases.The B element in the modified matrix was oxidized to form liquid phase to seal the surface of SiC coating,which delayed the oxidation process of SiC coating,preventing the oxidation medium from entering the interior of the compo-site and protects the fiber and interface layer,so that the long-term static oxidation resistance of SiC/SiC composites was improved significantly.