A356铝合金的表面改性与耐磨及耐蚀性能研究

Study on surface modification and wear and corrosion resistance of A356 aluminum alloy

为了提升A356铝合金的表面耐磨耐蚀性能,采用等离子喷涂的方法在A356铝合金基体表面制备了4种高熵合金涂层(FeCoCrNi和FeCoCrNi+Mn/Cu/Ti),对比分析了各等离子喷涂涂层的物相组成、显微形貌、硬度、耐磨和耐蚀性能。结果表明4种等离子喷涂涂层中都可见面心立方固溶体和氧化物的衍射峰。在FeCoCrNi中加入Cu/Ti后,涂层中还出现了Cu/Ti的衍射峰。4种等离子喷涂涂层厚度都介于210~300μm,涂层与基体界面以机械结合为主。4种等离子喷涂涂层的硬度、平均摩擦系数都高于A356铝合金基体,磨损率从低至高顺序为:FeCoCrNi(涂层Ⅰ)<FeCoCrNiTi(涂层Ⅳ)<FeCoCrNiMn(涂层Ⅱ)<FeCoCrNiCu(涂层Ⅲ)<基体。相较A356铝合金基体,涂层的腐蚀电位发生正向移动,腐蚀电流密度和点蚀电位减小,Nyquist圆弧半径、阻抗模值|Z|0.01 Hz和电荷转移电阻Rct增大。4种等离子喷涂涂层的耐蚀性能都优于A356铝合金基体,且涂层Ⅳ的耐腐蚀性能最好。

In order to improve the surface wear resistance and corrosion resistance of A356 aluminum alloy,four kinds of high entropy alloy coatings(FeCoCrNi and FeCoCrNi+Mn/Cu/Ti)were prepared on the surface of A356 aluminum alloy by plasma spraying.The phase composition,microstructure,hardness,wear resistance and corrosion resistance of plasma spraying coatings were compared and analyzed.The results show that the four kinds of plasma spraying coatings all have the diffraction peaks of face centered cubic solid solution and oxide,when the element Cu/Ti is added to FeCoCrNi,the Cu/Ti diffraction peaks also appear in the coatings.The thickness of the four plasma spraying coatings is between 210μm and 300μm,and the interface between the coating and the substrate is mainly mechanical.The hardness and average friction coefficient of the four plasma spraying coatings are higher than that of A356 aluminum alloy substrate,the order of wear rate from low to high is:FeCoCrNi(coating I)<FeCoCrNiTi(coating IV)<FeCoCrNiMn(coating II)<FeCoCrNiCu(coating III)<substrate.Compared with A356 aluminum alloy substrate,the corrosion potential of coating shifted forward,and the corrosion current density and pitting potential decreased,the Nyquist arc radius,impedance modulus|Z|_(0.01)Hz and charge transfer resistance Rct increased.The corrosion resistance of the four plasma spraying coatings is better than that of A356 aluminum alloy substrate,and the corrosion resistance of coatingⅣis the best.