炭/炭复合材料MoSi_2/SiC高温抗氧化复合涂层的制备及其结构

Preparation and structure of a MoSi_(2)/SiC high temperature anti-oxidative gradient coating for carbon/carbon composites

采用两段式包埋法工艺可制得涂层结构合理的复合梯度涂层,从里到外涂层结构为:S iC过渡层→S iC致密层→M oS i2/S iC双相层→以M oS i2为主的外层。随着制备工艺中高温阶段保温时间的延长,涂层表面以M oS i2为主的薄层越连续。涂层与基体的结合以化学结合为主,并有机械结合,结合强度高。用正硅酸四乙酯对涂层表面进行封闭处理,凝胶形成的S iO2可充填涂层表面裂纹并覆盖在涂层表面。在1 500℃高温空气中氧化,未封闭处理的涂层试样表现为氧化失重,封闭处理后的试样氧化增重。

An appropriately structured gradient coating on the surface of C/C composites, consisting of, from inner to outer, a SiC transiting layer, a SiC compacting layer, a MoSi2/SiC double phase layer and a MoSi2-containing outer layer, was prepared by a two-stage coating method. As the holding time at high temperature stage is increased, the MoSi2 outer layer becomes more continuous. The adhesion between the coating and the composites is mainly caused by a metallurgical bond and a mechanical bond. The surface of the coating is sealed by Si（ OC2H5 ）4, and SiO2 gel fills the cracks in the coating and covers it. Oxidation of the specimen with an unsealed coating causes mass loss, while the specimen with the sealed coating shows a mass gain in air at 1 500℃.