Mo5Si3-MoSi2/SiC复合涂层的高温抗氧化行为分析

Analysis on the oxidation behavior of Mo5Si3-MoSi 2/SiC multi-coating at high temperature

  • 摘要: 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%。

     

    Abstract: To improve the anti-oxidation property of graphite at high temperature,an Mo5Si3-MoSi2/SiC multi-coating was prepared by the chemical vapor reaction (CVR) and slurry method. The structure of the ulti-coating was studied by XRD,SEM and EDS analysis,and the oxidation behavior of the multi-coating at high emperature was investigated by the isothermal oxidation test and thermodynamics calculation. The results show that the Mo5Si3 and MoSi2 phases in the multi-coating are prone to produce the reactions of forming the MoO3 gas in air at 1823 K and result in the mass loss,while the mass gain in the initial oxidation stage (0~6 h) is primarily attributed to the dominating passive oxidation of SiC. As the main phases of the multi-coating can oxidize and form the SiO2 glass at high temperature,it enables the coating to have the excellent anti-oxidation ability and thermal shock resistance. After oxidation in air at 1823 K for 20 h and thermal cycling between 1823 K and room temperature 16 times,the mass loss of the coated sample is only 3.78%.

     

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