高功率光纤激光器熔覆Ni60A合金的显微组织及高温摩擦磨损特性

摘要

为获得耐磨性能优异的Ni60A合金涂层，采用高功率光纤激光熔覆系统制备出无裂纹Ni60A涂层。利用OM、SEM、XRD、EDS及显微硬度仪等分析测试手段，分别对熔覆层显微组织形貌、相组成、相分布、微区成分及显微硬度进行测定与分析；利用HT-500型磨损试验机研究不同载荷下熔覆层高温干摩擦磨损特性，理论计算体积磨损率；利用SEM和EDS分析磨损机理。结果表明：熔覆层组织主要由柱状γ­Ni固溶体枝晶、层片状Ni­Ni3B共晶、胞状M23C6和颗粒状CrB组成；涂层平均显微硬度为560HV0.2，远高于基材的显微硬度220HV0.2；施加载荷为3 N时，熔覆层摩擦因数最低、磨损率最小，其值分别为0.82和4.8×10-5 mm3/(N∙m)，主要磨损机制为轻度磨粒磨损和氧化磨损。%The crack­free Ni60A coating was fabricated by fiber laser cladding system to obtain good wear­resisting Ni60A coating. The microstructure morphology, phase constitution, phase distribution, the micro­zone composition and microhardness of the coating were measured and analyzed by OM, SEM, XRD, EDS and microhardness tester, respectively. The high temperature tribological behaviors under different applied loads were studied by HT-500 wear­testing machine, and volume abrasion rates were calculated. The wear mechanism was analyzed by SEM and EDS. The results indicate that microstructure of the coating consists of columnar γ­Ni dendrite, lamellar Ni­Ni3B eutectic, cellular M23C6 eutectic and granular CrB. The microhardness of the coating is 560HV0.2, which is far higher than that of the substrate (220HV0.2). At an applied load of 3 N, the friction coefficient and wear rate of the coating are all the minimum, separately with values of 0.82 and 4.8×10-5 mm3/(N∙m), and the wear mechanism mainly includes mild abrasive wear and oxidation wear.