目的 在C/C复合材料表面制备SiC涂层，提高C/C复合材料抗烧蚀性能。方法 采用真空等离子喷涂技术在C/C复合材料表面制备纯Si涂层，在惰性气氛保护下对涂层高温热处理，纯Si涂层与C元素在高温下反应，原位生成SiC涂层。利用电弧加热器在不同烧蚀温度下，分别考核涂层的驻点烧蚀性能，并采用OM、SEM、EDS和XRD等对烧蚀前后的微观形貌和物相成分进行分析。结果 在C/C复合材料表面制备了致密的SiC涂层，涂层中没有明显的裂纹存在，并在涂层下方产生较深的渗透区域，深度超过涂层厚度。制备的SiC涂层在1400 ℃下烧蚀50 s，涂层完整，具有良好的驻点烧蚀性能；在1600 ℃和1650 ℃下烧蚀50 s，涂层部分剥落，C/C复合材料基体产生烧蚀。结论 SiC涂层在高温下氧化成SiO2玻璃态膜，并覆盖在C/C复合材料表面，对基体具有良好的保护作用。随着烧蚀温度的提高，在超音速气流的冲刷下，由于热膨胀系数不匹配和SiC主动氧化的原因，涂层在烧蚀面边缘出现剥落，且剥落现象越来越严重，涂层失去对C/C基体的保护作用，烧蚀性能下降。

The work aims to improve ablation resistance of C/C composites by preparing SiC coating on C/C composites. A pure Si coating was prepared on C/C composites by adopting vacuum plasma spraying (VPS) technology and then SiC coating was generated in situ by performing high-heat treatment in inert atmosphere as pure Si coating reacted with C element at high temperature. The stagnation point ablation property of coating was evaluated on arc heater at different temperature. Microstructure and phase composition of the coating before and after ablation were characterized with optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometer. A compact SiC coating free from obvious cracks was prepared on C/C composites. Deep permeation zone was present beneath the coating and the depth exceeded coating thickness. As-prepared SiC coating was complete and of good stagnation point ablation property as the coating has been ablated at 1400 ℃ for 50 s. However, local coating peeled off at 1600 ℃ and 1650 ℃ after 50 s ablation to make the C/C composites ablated. The SiO2 glassy scale covering the surface of C/C composites is formed on SiC coating at high temperature, which can protect the C/C substrates. As the ablation temperature rises, provided with erosion of hyper-sonic flow, mismatched thermal expansion and active SiC oxidation, the temperature increasingly peels off along edges of ablated surface and cannot protect C/C substrate any more, so that ablation resistance of the coating decreases.