激光熔覆NiCoCrAlY/HfB2复合涂层结构及高温摩擦学性能

摘要

利用激光熔覆技术在纯钛表面制备了NiCoCrAlY/HfB2复合涂层.用XRD和SEM分析了涂层的组成和组织结构,在SRV - IV微动摩擦磨损试验机上对涂层不同温度下的摩擦磨损性能进行对比测试,采用SEM和三维表面轮廓仪对磨损后试样、对偶球和磨屑的形貌进行了分析.结果表明:NiCoCrAlY/HfB2复合涂层主要组成为NiTi、HfB2、TiB2、Co3Ti、CrTi4和Hf3Ni7相,复合涂层与基材冶金结合,涂层晶体结构主要为块状晶.涂层的平均显微硬度约为850HV0.2,是基材硬度的4.25倍.在20℃、100℃、300℃和500℃摩擦测试温度下涂层的摩擦因数和磨损率随温度的升高而减小,复合涂层的磨损率在10-4～10-5 mm3/Nm数量级,具有较好的高温耐磨性能,涂层的磨损机制主要为磨粒磨损和黏着磨损.%NiCoCrAlY/HfB2 composite coating was prepared on pure Ti substrate using laser cladding technology. The composition and microstructure of the fabricated coating was analyzed by XRD and SEM. The tribological properties of NiCoCrAlY/HfB2 coating were examined by SRV-IV tester at different temperature. The morphologies of the worn surface and debris were analyzed by SEM and three dimensional non-contact surface mapping. The results show that NiCoCrAlY/Hflfe composite coating is mainly composed of NiTi, HfB2, TiB2, CO3Ti, CrTi4 and Hf3Ni7 phases, and the composite coating is metallurgically bonded to the substrate. The microhardness of the coating is about 850 HV0.2, which is 4. 25 times as much as the pure Ti substrate. Under the temperature of 20 ℃ ,100 ℃ ,300 ℃ and 500 ℃, NiCoCrAlY/HfB2 composite coating represents excellent wear resistance, the wear rate of which is 10-4-10-5mm3/Nm order of magnitude. The friction coefficient and wear rate of the NiCoCrAlY/HfB2 composite coating all decreased with increasing temperature. The wear mechniasim of composite coating is dominated by abrasive wear and adhesion wear.