激光熔覆Al_2O_3-TiO_2涂层的工艺与性能研究

Process Analysis and Properties of Laser Cladding Al_2O_3-TiO_2 Coating

在钛合金（Ti-6Al-4V）表面利用激光熔覆技术进行了直接熔覆Al_2O_3-13wt%TiO_2涂层的工艺研究。利用光学显微镜（OM）、扫描电子显微镜（SEM）和显微硬度计研究了激光熔覆Al_2O_3-TiO_2涂层工艺参数对熔覆涂层质量的影响,分析了熔覆过程中涂层熔池的对流现象、涂层的显微组织和显微硬度分布情况。当激光功率在2 200~2 800 W的范围内,扫描速度为500mm/min时,获得了界面结合良好的Al_2O_3-TiO_2涂层,且涂层的内部组织均匀,不存在明显的裂纹和气孔。经激光熔覆的Al_2O_3-TiO_2涂层表现出明显的流线型特征,其中的未熔颗粒分布均匀,大多以流线形式分布在涂层内部,对涂层起到了一定的增强作用。钛合金基材的硬度为360~390HV0.3,激光熔覆涂层的显微硬度为1 000~1 300 HV0.3,达到了基体硬度的3倍左右。

In this paper,Al_2O_3-13wt%TiO_2coating preparation process were studied,which were prepared on titanium alloy（Ti-6Al-4V）by directly laser cladding.Optical microscope（OM）,Scanning electron microscope（SEM）and Vickers microhardness tester were used to identify the effect of coating process parameters on the quality of cladding coating and analyzed the convection in the cladding molten pool.The microstructure and microhardness of the coating were also investigated.When the laser power in the range of 2 200~2 800 W,scanning speed of 500mm/min,obtained a good interface bonding Al_2O_3-TiO_2 coating and uniform microstructure without obvious cracks and pores.The coatings exhibited significantly streamlined features.The unmelted particles tend to distribution as streamline formula in the coating,which enhanced the mechanical behavior of the coating.The microhardness of the substrate is 360~390HV0.3,while the coatings reach 1 000~1 300 HV0.3,which is about three times than that of the substrate.