镁合金表面火焰喷涂及激光重熔Al-Si合金涂层的研究

Study of Flame Sprayed and Laser Remelted Al-Si Coatings on Magnesium Alloy

采用火焰喷涂及激光重熔工艺在镁合金基材表面制备了Al-Si合金涂层,考察了涂层激光重熔处理前后的组织及性能。结果表明:激光重熔处理前,涂层组织不够致密,涂层硬度较低;激光重熔后,涂层变得组织致密、均匀,元素扩散剧烈,界面呈冶金结合,涂层硬度可高达270HV。激光重熔处理使涂层和基材表面层都发生熔融,涂层厚度大幅增加。分析表明,激光重熔后涂层的组织非常致密,与其成分所对应的合金具有很窄的凝固温度范围即具有很好的铸造性能有关。研究结果表明采用火焰喷涂及激光重熔工艺在镁合金表面制备高质量Al基厚涂层可行。

Al-Si coatings on magnesium alloy substrate were prepared using flame spraying and laser-remelting technology.The microstructures and properties of the coatings before and after laser-remelting treatment were examined.The results show that the coatings prepared by merely flame spraying are not satisfactory coatings,with certain imperfections such as insufficiently dense microstructures and a lower hardness.After laser-remelting,a high quality coating was successfully developed.This coating presented many characterizations,such as dense and uniform microstructures,intensive element diffusion,good metallurgical bonding in interface,and a high hardness（HV270）.Moreover,the laser-remelting treatment made the top in substrate along with the coating melted and inter-fused,leading to a considerable increase in coating thickness.It is believed that the compact microstructure of the coating can be ascribed to the chemical composition in the coating,which corresponds to a very narrow solidification temperature range,i.e.excellent castability.The present results demonstrate the possibility of preparing superior Al-Si thick coatings on magnesium alloy through flame spraying and laser-remelting approaches.