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采用化学气相反应法和料浆刷涂反应法,在石墨表面制备了Mo5Si3-MoSi2/SiC复合涂层,借助X射线衍射仪、扫描电镜及能谱等分析手段,研究了涂层的结构;通过恒温抗氧化实验及热力学分析,重点研究了涂层的高温抗氧化行为。结果表明:在1823 K的氧化氛围中,复合涂层中的Mo5Si3、MoSi2组元易氧化生成MoO3气体并导致涂层失重;而氧化初期(0~6 h)涂层试样的增重则主要与SiC的惰性氧化主导有关。由于复合涂层各组元在高温下都能氧化生成SiO2玻璃,使涂层具有良好的高温抗氧化及热震性能;经20 h、16次循环热震实验后,涂层试样的氧化失重率只有3.78%。
Mo5Si3-MoSi2 / SiC composite coatings were prepared on graphite by chemical vapor-phase reaction and slurry brushing reaction. The structure of coatings was studied by means of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Thermostatic oxidation experiments and thermodynamic analysis, focusing on the high temperature oxidation of the coating behavior. The results show that the Mo5Si3 and MoSi2 components in the composite coating easily oxidize to form MoO3 gas and lead to weight loss in the oxidizing atmosphere of 1823 K, while the weight loss of the coatings during the initial oxidation (0-6 h) is mainly And SiC inert oxidation dominated. As the components of the composite coating can be oxidized to SiO2 glass at high temperature, the coating has good high temperature oxidation resistance and thermal shock resistance. After 20 h and 16 cycles of thermal shock test, the oxidation loss The rate is only 3.78%.