石墨基体等离子喷涂TiC涂层耐烧蚀性能研究

Investigation into Ablation-Resistant Properties of TiC Coating Deposited by Plasma-Spraying for Graphite Substrate

采用等离子喷涂方法在石墨基体上制备出较为致密的Mo黏结层和TiC耐烧蚀涂层,利用SEM,XRD表征氧乙炔烧蚀试验前后涂层的表面形貌与相结构.结果表明:随着烧蚀距离减小,涂层质量烧蚀率呈现先增加后减小的趋势,最终趋于稳定;随着烧蚀时间增大,致密化区域快速增大,涂层质量烧蚀率略有增加.烧蚀过程中涂层经历了点状熔融、线形连接、网状连接和完全致密4个过程.TiC涂层在高温燃流作用下氧化生成TiO2并熔融,在燃流冲刷和表面张力作用下发生黏性流动,形成TiO2致密层,从而减小了机械剥落,降低了涂层质量烧蚀率.

The comparatively dense Mo bonding layer and TiC ablation-resistant layer was deposited by plasma spraying on graphite substrate.The morphology and the phase structure of coatings,tested with and without oxy-acetylene ablation,were characterized and compared by SEM and XRD.Results indicated that with decreasing the ablation distance,the coating mass ablation rate increased at the initial stage and then decreased,thus finally tended towards stability.As the ablation time increased,the densification region rapidly increased,while the coating mass ablation rate only slightly increased.The ablation process was composed of four stages,namely point-like fusion,linear connection,net connection and perfect densification.Ablated with high temperature fuel flow,the surface TiC layer was transformed to molten TiO2.Due to the surface tension and viscous flow,a dense TiO2 layer was finally formed,whereupon reducing the mechanical denudation as well as mass ablation rate.