Ti-6Al-4V合金激光熔覆γ-NiCrAlTi/TiC+TiWC_2/CrS+Ti_2CS高温自润滑耐磨复合涂层研究

Study on γ-NiCrAlTi/TiC+TiWC_2/CrS+Ti_2CS High-Temperature Self-Lubricating Wear Resistant Composite Coating on Ti-6Al-4V by Laser Cladding

为提高Ti-6Al-4V钛合金的摩擦学性能,以金属陶瓷NiCr-Cr3C2和自润滑颗粒WS2复合合金粉末为原料,采用激光熔覆技术在钛合金表面制备出了以硬质TiC和TiWC2为耐磨增强相、Ti2CS和CrS金属硫化物为自润滑相的高温自润滑耐磨复合涂层。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)分析了涂层的物相及显微组织结构;分别在室温、300℃和600℃时利用Si3N4陶瓷球对磨来测试涂层和基体的干滑动磨损性能,并分析了其磨损机理。结果表明:复合涂层的平均硬度为1005HV0.2,约为基体(360HV0.2)的3倍,从室温到600℃,由于增强相TiC、TiWC2和自润滑相CrS、Ti2CS的综合效应,复合涂层的摩擦系数和磨损率相比基体均显著降低,具有良好的高温自润滑耐磨性能。

To enhance the tribological behaviors of Ti-6Al-4V alloy, high-temperature self-lubricating wear resistant composite coatings reinforced with hard TiC and TiWC2 carbides, self-lubricating Ti2CS and CrS sulfides are fabricated by laser cladding. The phase compositions and microstructures are investigated by X-ray diffractometer （XRD）, scanning electron microscope （SEM） and energy dispersive spectrometer （EDS）, respectively. Sliding wear tests of the composite coating and substrate are conducted at ambient temperature, 300 ℃ and 600 ℃, with the Si3 N4 ceramic ball as the counter-body, and the corresponding wear mechanisms are discussed. Results indicate that the mean microhardness of the composite coating （1005 HV0.2 ） is about 2 times higher than that of substrate （360 HV0.2 ）. From ambient temperature to 600 ℃ , due to the combined effects of hard TiC and TiWC2 carbides and self-lubricating Ti2 CS and CrS sulfides, both the friction coefficient and wear rate of the composite coating decrease in comparison with the substrate. The composite coating has excellent high temperature self-lubricating and wear resistant properties.