C/SiC表面SiC涂层氧化的显微CT无损检测与分析

对C/SiC复合材料表面SiC涂层在1300 ℃干氧和湿氧环境中退火处理60 h, 利用显微CT技术对高温氧化后的SiC涂层进行无损检测。通过重构SiC涂层不同深度的氧化形貌, 并利用SEM、EDS和XRD进行辅助验证, 得到沿SiC涂层表面和厚度方向的氧化形貌。结果表明: 显微CT能有效地检测氧化后SiC涂层中存在的氧化产物SiO₂及其氧化深度, 其在表面及深度方向均呈非均匀分布; 在干氧环境中SiC涂层的氧化面积沿着涂层的深度方向呈减少趋势, 而在湿氧环境中SiC涂层的氧化面积沿着涂层的深度方向呈先增加后递减的趋势, 验证了C/SiC复合材料表面SiC涂层在干氧和湿氧中不同的氧化机制。 

Nondestructive testing and analysis of SiC coating on surface of C/SiC composites after oxidation with Micro CT

The SiC coatings on the surface of C/SiC composites which were annealed in the dry and wet oxidizing environment at 1300 ℃ for 60 h were examined nondestructively using X-ray microtomography (Micro CT). The oxidation morphology along the coating surface and depth direction was investigated by reconstructing images of different depth SiC coatings assisted with SEM, EDS and XRD. The results demonstrate that Micro CT is applicable to distinguish the oxidation products of SiO₂ in the SiC coating and the oxidation depth. Oxidation products SiO₂ along the SiC coating surface and depth direction is non-uniform distribution. With increasing depth of the coating, the oxidized area percentage of the coating decreases in the dry oxidizing environment; and first increases and then decreases in the wet oxidizing environment. The different oxidation mechanisms of SiC coatings in the dry and wet oxidizing environment are confirmed by Micro CT.