激光重熔等离子喷涂Al_2O_3–13%TiO_2涂层的组织结构

Microstructure of Plasma-sprayed Al_2O_3-13%TiO_2 Coating with Laser Remelting

采用等离子喷涂方法制备Al2O3–13%TiO2涂层,对涂层进行激光重熔处理。利用电子扫描显微镜(SEM)观察涂层断口组织,金相截面组织和金相表面组织形貌,分析激光重熔处理后涂层的凝固过程。结果表明:激光重熔处理,使涂层由块状结构转变为平行排列,垂直于基体方向生长的柱状晶和柱状枝晶结构。由于金属基体温度低、散热快,使得陶瓷涂层上下温差大,诱发了陶瓷晶粒的定向生长,这是使陶瓷晶粒垂直于基体生长的主要原因。

Al2O3-13 %TiO2 coating was prepared by two steps.The first step is plasma spraying and the second step is laser remelting.Fractured morphology,metallographic cross-section morphology and surface morphology of the coating were investigated by scanning electron microscopy（SEM）,solidification process of the coating after laser remelting was analysed.The results show that： after laser remelting,the structure of the coating with a massive morphology change into the parallel cellular and cellular dendritic crystal,perpendicular to the matrix.Metal matrix temperature is lower than the coating,heat dissipation is more quickly,making the temperature difference between the upper and lower ceramic coating,induced the growth of the ceramic grain orientation,Therefore,the growth direction of the ceramic perpendicular to the substrate.