| 摘要: |
| 为了提高C/SiC复合材料耐高温性能，采用泥浆浸渍裂解与真空化学气相沉积(CVD)在材料表面制备了SiC/ CVD SiC复合涂层，通过XRD、SEM分析了涂层组成与结构；研究了复合涂层的高温抗氧化(700~1 500 ℃)和抗热震性能。结果表明，泥浆浸渍法制备的SiC涂层具有一定的封孔效果，可使材料开孔率下降，但高温抗氧化效果并不佳， 1 200 ℃氧化10 min后材料弯曲强度保留率下降明显仅有86%。CVD SiC涂层结构致密，与SiC封孔涂层结合较好，在700~1 500 ℃具有较好的抗氧化效果，随着氧化温度的升高，氧化后涂层完好，表面O元素逐渐增加，材料失重率缓慢增加但不大于0.5%，且材料性能并未下降。涂层材料在1 200 ℃-10 min 短时热震5次后材料弯曲强度保留率仍有95%以上，且未出现开裂、剥落等热震损伤。在1 200 ℃-30 min长时热震10次后，涂层材料基本被完全氧化，材料失去保护作用，弯曲强度下降至90%左右。 |
| 关键词: C/SiC复合材料 涂层 氧化 抗热震性能 |
| DOI： |
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| 基金项目:国防基础科研计划（JCKYS2020603C016） |
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| Study on Oxidation Resistance and Thermal Shock Resistance of SiC/CVD SiC Composite Coating |
| LIU Qian,CHEN Sian,PAN Yong |
| (Key Laboratory of New Ceramic Fibers and Composites, National University of Defense Technology;Beijing Institute of Near Space Vehicle System Engineering) |
| Abstract: |
| In order to improve the high temperature of C/SiC composites, the SiC/CVD SiC composite coatings were prepared by mud impregnation cracking and vacuum chemical vapor deposition(CVD).The composition and structure of the coating were analyzed by XRD and SEM.The oxidation resistance and thermal shock resistance of the composite coating at high temperature(700~1 500 ℃) were investigated. Results show that the SiC coating prepared by slurry impregnation method has a certain hole sealing effect, and this can decrease the opening rate of the composite,but the effect of high temperature anti-oxidation is not good. The bending strength retention rate is only 86%, and decreases significantly after oxiding 10 minutes at 1 200 ℃.The structure of CVD SiC coating is compact combined well with SiC sealing coating. The composite coatings have good effect on the oxidation resistance. With the increase of oxidation temperature, the element of O on the surface increase gradually, the weight loss rate of the composite increases slowly but not exceeds 0.5%, but the properties of composite does not decrease , and the coating is still compact.After 5 times short-term thermal shocks at 1 200 ℃ for 10 minutes，the retention rate of bending strength is still more than 95%, and there is no thermal shock damage such as cracking and spalling. After 10 times of long-term thermal shockat 1 200 ℃ for 30 minutes，the coating material is almost completely oxidized, losing its protective effect, and the bending strength decreases to about 90%. |
| Key words: C/SiC composites Coating Oxidation Thermal shock resistance |