Ti6Al4V合金激光原位合成自润滑复合涂层高温摩擦学性能

为提高Ti6Al4V合金的高温摩擦学性能,采用激光熔覆技术在其表面原位合成多相混杂金属基高温自润滑耐磨复合涂层,熔覆粉末的成分为Ni60-16.8%TiC-23.2%WS_2(质量分数,下同),系统地研究复合涂层的显微组织、物相结构及其在20,300,600,800℃下的摩擦学性能和相关磨损机理。结果表明:复合涂层的显微硬度(701.88HV_0.5)约为基体(350 HV_0.5)的2倍;由于原位合成固体润滑相(Ti_2SC/TiS/NiS/TiO/TiO_2/NiCr_2O_4/Cr_2O_3)和硬质相(W,Ti)C_1-x/TiC/Cr_7C_3的协同作用,复合涂层的耐磨减摩性能明显优于基体。随着温度升高,涂层和基体的摩擦因数和磨损率均呈下降趋势,在800℃时复合涂层和基体的摩擦因数分别为0.32和0.43,磨损率分别为1.80×10^-4,2.92×10^-5mm/Nm。在800℃下塑性变形、分层和氧化磨损为基体主要磨损机理,复合涂层以氧化磨损和轻微的黏着磨损为主。

High temperature tribological properties of laser in-situ synthesized self-lubricating composite coating on Ti6Al4V alloy

In order to improve the high temperature tribological properties of Ti6Al4V alloy, multi-phase hybrid metal matrix high-temperature self-lubricating anti-wear composite coating was in-situ synthesized by laser clad with the powder precursor of Ni60-16.8%TiC-23.2%WS 2(mass fraction, the same below). The microstructure, phase composition and tribological properties as well as the corresponding wear mechanisms of the composite coating at 20, 300, 600, 800℃ were analyzed systematically. The results show that the microhardness of the composite coating (701.88HV 0.5 ) is about two-fold of the substrate (350HV 0.5 ). Due to the synergetic effect of the in-situ synthesized solid lubricants Ti 2SC/TiS/NiS/TiO/TiO 2/NiCr 2O 4/Cr 2O 3 and hard phases (W,Ti)C 1 -x /TiC/Cr 7C 3, both the wear resistant and friction reducing capabilities of the composite coating are better than that of the substrate. With the increase of temperature, the friction coefficient and wear rates of the composite coating and the substrate all exhibit decreasing trend, i.e., the friction coefficient of the composite coating and substrate are 0.32, 0.43 and wear rates are 1.80×10 -4 , 2.92×10 -5 mm/Nm at 800℃, respectively. The main wear mechanisms of substrate are mainly plastic deformation and delamination as well as oxidation wear, while the composite coating is predominated by the oxidation wear and slight adhesive wear at 800℃.