为提高C/C复合材料在高温富氧环境中的抗氧化性能,采用两步刷涂+化学气相沉积法在C/C复合材料表面制备含Si3N4、MoSi2、TaC等添加剂的ZrB2-SiC基多层复合陶瓷涂层.利用XRD和SEM等分析测试手段研究涂层的物相组成和微观结构,并分析讨论涂层在900和1500℃的等温抗氧化机理.结果表明:利用两步刷涂+化学气相沉积法制备的ZrB2-SiC基复合陶瓷涂层整体厚度约为200μm.Si3N4、MoSi2可很好地促进ZrB2-SiC基氧阻挡层的高温烧结,使涂层致密化,并提高涂层在900℃的抗氧化性能;与之相比,TaC则不能很好地发挥致密化作用,对涂层在900℃时抗氧化性能的提高有限.在900℃时,ZrB2-SiC基陶瓷涂层的氧化过程主要受氧在涂层孔隙等缺陷中的扩散所控制,添加剂主要通过改变涂层的致密化程度来影响涂层的抗氧化性能.在1500℃氧化过程中,涂层抗氧化性能恶化,但致密的化学气相沉积SiC封填层的引入可显著改善涂层在1500℃时的抗氧化性能,涂层表面生成了完整的含有ZrO2和ZrSiO4等高熔点颗粒的SiO2玻璃态氧化膜,为基体提供有效的氧化防护.%To improve the anti-oxidation performance of C/C composites under high temperature and oxygen enriched environment, ZrB2-SiC based ceramic coatings with Si3N4, MoSi2 and TaC addition were prepared by two-step slurry painting+chemical vapor deposition (CVD). Phase composition and microstructure of the as-prepared coating were investigated by using X-ray diffractometry and scan electron microscopy, and the isothermal anti-oxidation mechanism at 900℃ and 1500℃ were also analyzed and discussed. The conclusions are as follows, the thickness of the as-prepared ZrB2-SiC based composite ceramic coating is about 200μm. The densification and the anti-oxidation properties of the coating can be improved by the addition of Si3N4 and MoSi2, effectively. While the anti-oxidation properties of the coating can not be improved by the addition of TaCeffectively at 900℃. At 900℃, the oxidation process of ZrB2-SiC ceramic coating was mainly controlled by the diffusion of oxygen in pore and other defects in the coating. The anti-oxidation property of coating can be improved by the addition by affecting the density of coating. In the oxidation process of 1500℃, the oxidation resistance of the coating decreases. The introduction of the compact structure of CVD SiC sealing layer can improve the oxidation resistance significantly. At 1500℃, in oxidation process, SiO2 glassy oxide film with ZrO2 and ZrSiO4 on the coating is generated, this can provide effective oxidation protection for the substrate.
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