TC4表面单道与多道搭接激光熔覆自润滑涂层微观组织对比研究

Comparative Study of Self-lubricating Coatings Microstructure on TC4 Alloy Surface Prepared by Single-pass Laser Cladding and Multitrack Laser Cladding

在TC4表面预制Ni60/20%WS2粉末,分别采用单道与多道搭接激光熔覆技术制备了自润滑涂层。结果表明,多道搭接激光熔覆层比单道激光熔覆层更容易产生裂纹,开裂方向与扫描方向有一定夹角。多道搭接激光熔覆层和单道激光熔覆层的主要成分相同,都生成了润滑相、硬质相,但多道搭接激光熔覆层中的硬质相和润滑相分布的密度较小且组织较粗大。多道搭接激光熔覆层的显微硬度分布在800~1 000HV0.5之间,单道激光熔覆层的显微硬度分布在950~1 150HV0.5之间,前者显微硬度偏低一方面是由于单道激光熔覆层的细晶强化作用,另外一方面是因为多道搭接激光熔覆层的硬质相分布密度较低。

Ni60/20%WS2 powder was precast on surface of TC4 alloy,and self-lubricating coating was then prepared by respectively adopting single-pass laser and multitrack laser cladding technology.The result showed that multitrack laser cladding was more likely to produce crack,and the cracking direction had a certain angle with the scanning direction.The main ingredients of multitrack laser-clad coating and single-pass laser-clad coating were the same,all produced lubricating phase and hard phase.But the former had lower distribution density of lubricating phase and hard phase,and coarser alloy grains.The microhardness of multitrack laser-clad and single-pass laser-clad coatings was 800-1 000HV0.5and 950-1 150HV0.5respectively.The grain refinement strengthening effect and higher hard phase concentration of single-pass laser-clad coating results in a relatively high microhardness compared to multitrack laser-clad coating.