炭/炭复合材料用SiC-Glass涂层的高温氧化机理

采用包埋法和预涂-烧结法相结合的组合工艺在炭/炭(C/C)复合材料表面制得SiC-Glass复合涂层, 并借助X射线衍射仪(XRD)和扫描电镜(SEM)对该复合涂层进行了表征, 研究了涂层C/C试样在不同温度下的氧化动力学规律。结果表明: 复合涂层具有双层结构, 包埋SiC内层由β-SiC相和少量游离硅相组成, 外层由MoSi₂颗粒掺杂的硼硅酸盐玻璃构成; 内外层之间结合紧密; 在1300~1600℃的空气气氛中, SiC-Glass涂层表现出良好的抗氧化性能, 其氧化激活能为118.1kJ/mol, 氧化主要受控于氧在Glass层中的体扩散速率; 在1600℃空气气氛中氧化65h后, SiC-Glass涂层C/C试样的氧化失重率仅为1.02%。 

Oxidation mechanism of SiC-Glass coating for protecting carbon/carbon composites from oxidation at high temperatures

An SiC-Glass multi-layer coating was fabricated on the carbon/carbon (C/C) composites by using the pack cementation technique and the precoating-sintering process. The as-prepared multi-layer was characterized by XRD and SEM analyses. The oxidation kinetics of the coated C/C samples was also investigated at different temperatures. The results indicate that the multi-coating is composed of two layers. The inner layer consist of β-SiC phase and a small quantity of silicon phase. The outer layer is a borosilicate glass layer modified by MoSi2 particles. Additionally, the multi-coating has good interface bonding between the two layers. The experimental data of the oxidation tests show that the SiC-Glass coating exhibits an excellent oxidation resistance in air in the temperature range from 1300℃ to 1600℃, and the oxidation activation energy of the coated C/C is 118.1 kJ/mol. After oxidation at 1600℃ in air for 65 hours, the mass loss of the SiC-Glass coated sample is only 1.02%.