氧-乙炔火焰喷涂Al-Mg3Sb2复相涂层的腐蚀磨损性能

Corrosion and wear properties of Al-Mg3Sb2 composite coatings prepared by oxy acetylene flame spraying

采用氧-乙炔火焰喷涂技术在AZ31B镁合金表面制备了不同组分的Al-Mg3Sb2复相涂层。利用SEM、XRD和显微硬度计分析了涂层的形貌、物相和硬度;采用腐蚀磨损试验仪测试了涂层在3.5%NaCl溶液中的腐蚀磨损性能;通过超景深三维显微镜测试了涂层的磨痕宽度、深度及磨损体积。结果表明：涂层的显微硬度随着金属间化合物Mg3Sb2（硬质相）的增多而增加;Mg3Sb2相的腐蚀倾向低于Al,因此涂层的开路电位随着Mg3Sb2相的增多而上升,加载之后,腐蚀产物膜被去除,涂层的开路电位下降,且下降的幅度随耐蚀相Mg3Sb2的增多而减少,卸载之后,由于Al的钝化作用,涂层的开路电位上升,其幅度随Al的增加而增加;涂层的摩擦系数随硬质相Mg3Sb2的增加而降低,涂层的磨损率也降低,20%Al涂层的体积磨损率为1.44 mm3·N-1·m-1,比纯Al涂层下降了88.01%;随Al含量的降低,涂层的磨痕由最初较严重的塑性变形逐渐转变为剥落坑。

Al-Mg3Sb2 composite coatings with different compositions were prepared on the surface of AZ31 B magnesium alloy by oxy acetylene flame spraying.The cross-section morphology,phases and microhardness of the coatings were analyzed by means of SEM,XRD and microhardness test.The corrosion and wear properties of the coatings in 3.5% Na Cl solution was investigated by electrochemical corrosion tribometer.The widths,depth and wear volume of the coatings were tested by ultra-deep field 3 D microscope.The results show that the average microhardness of the coatings increases with the increasing of intermetallic compound Mg3Sb2（hard phase）,and because the corrosion tendency of Mg3Sb2 phase is lower than that of Al,the open circuit potential of the coatings increases with the increasing of Mg3Sb2 content.After loading,the corrosion product films were removed and the open circuit potential of the coatings decreases,and the decreasing rate is reduced with the increasing of the corrosion resistance phase Mg3Sb2.After unloading,the open circuit potential of the coatings increases due to the passivation of Al,and the increasing rate rises with the increasing of Al.The friction coefficient of the coatings increases with the increasing of Mg3Sb2 content and the wear rates decrease.The wear rate of 20% Al coating is 1.44 mm3·N-1·m-1,which is 88.01% lower than that of pure Al coating.With the decreasing of Al content,the wear scar of the coatings changes from the initial severe plastic deformation to the spalling pit.