| 摘要: |
| 碳 / 碳(C / C)复合材料表面涂层在制备与服役过程中易出现裂纹、凹坑和孔洞等缺陷，使涂层失去完整性而极易导致防护失效，目前常用的解决方法为更换整体涂层，成本高、工艺复杂、耗时长，因此快速高效的涂层轻微缺陷修复技术是解决这一难题的有效途径。通过大气等离子焰流在 C / C 复合材料表面 SiC-ZrB2 (SZ)涂层表面预先构造缺陷，采用异丙醇以及高温下性能稳定的含硼聚氮硅烷胶粘剂作为修复剂，以 SiC-ZrB2粉末作为改性填料，Al2O3作为烧结助剂，对 SZ 涂层缺陷进行修复，研究修复前后涂层的微观结构演变与烧蚀防护性能。结果表明：经等离子焰流烧蚀后，未修复的 SZ 涂层试样中心出现圆形凹坑缺陷，裸露出 C / C 复合材料基底；而对于修复后的涂层试样，修复剂热解生成的 SiBCN 陶瓷和改性陶瓷填料均匀覆盖于缺陷处，使涂层保持较高完整性，且在氧乙炔烧蚀下生成致密的 SiO2玻璃膜可有效阻挡氧扩散，保护 C / C 复合材料免受机械冲蚀；修复后的涂层试样在氧乙炔焰流下烧蚀 60 s 后线烧蚀率与质量烧蚀率分别为 0.65 μm / s 和?0.28 mg / s， 相比于未修复涂层试样分别降低了 83.54%和 129.47%，修复后涂层的抗烧蚀性能得到显著提升。 |
| 关键词: C / C 复合材料 SiC-ZrB2涂层 缺陷修复 抗烧蚀性能 |
| DOI：10.11933/j.issn.1007?9289.20220218003 |
| 分类号:TB332 |
| 基金项目:国家自然科学基金资助项目(52125203) |
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| Defect Repair and Ablation Resistance of the Damaged SiC-ZrB2 Coating for C / C Composites |
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WANG Weiyan, FU Qiangang, HU Dou, XIE Wei, LIU Tianyu
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Shaanxi Province C / C Composites Technology Research Center, Northwestern Polytechnical University, Xi’ an 710072 , China
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| Abstract: |
| Defects such as cracks, pits and holes, appear in the coatings of carbon / carbon (C / C) composite materials during the preparation and service process, which make coatings lose their integrity and lead to protection failure. Replacing the integral coating as a commonly used solution is expensive, complicated and time-consuming. Therefore, a fast and efficient repairing technology for minor defects on coatings is an effective way to solve this problem. Defects are pre-fabricated on the surface of SiC-ZrB2 (SZ) coated C / C composites by supersonic atmospheric plasma flame. To repair the defects of the SZ coating, isopropanol and boron-containing polynitrosilane adhesive with stable performance at high temperatures are used as repairing agents. SiC-ZrB2 and Al2O3 are used as modified filler and sintering aid, respectively. The microstructure and ablation resistance of the coating before and after repair are studied. The results show that circular pit defects appear in the center of the coating sample after plasma flame ablation, exposing the C / C composite substrate. For the coating sample after repair, SiBCN ceramics and modified ceramic fillers generated by the pyrolysis of the repair agent cover the defects evenly, and thus the coating sample maintains high integrity. A dense SiO2 glass film can be formed under oxyacetylene ablation, which effectively blocks oxygen diffusion and protect C / C composites from mechanical erosion. The repaired coating sample shows a better ablation resistance under oxyacetylene flame flow. After ablated for 60 s, its line ablation rate and mass ablation rate are 0.65 μm / s and -0.28 mg / s, respectively, which decrease by 83.54% and 129.47% compared with the unrepaired coating samples, suggesting that the ablation resistance of the repaired coating is significantly improved the unrepaired coating samples, suggesting that the ablation resistance of the repaired coating is significantly improved |
| Key words: C / C composites SiC-ZrB2 coating defect repair ablation resistance |
