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利用电弧喷涂和热扩散技术在AZ91D镁合金表面制备了复合涂层;采用扫描电镜、XRD衍射分析仪、动电位极化曲线测试等方法对复合涂层的微观形貌、相结构组成及在3.5%Na Cl溶液中的腐蚀行为进行研究与探讨。结果表明,AZ91D镁合金喷涂铝涂层经固态扩散锌处理后,获得了均匀致密的复合涂层,XRD结果显示,涂层由Zn-Al金属间化合物Zn Al2O4、Mg2Zn11及Al、Zn构成;极化曲线结果显示,复合涂层的自腐蚀电位正移到-1.36V,较AZ91D镁合金基体及铝涂层试样分别正移了约230、130m V;复合涂层自腐蚀电流密度4.7×10-5A·cm-2,较基材自腐蚀电流密度3.9×10-4A·cm-2降低。动电位极化曲线测试结果显示,形成的复合涂层组织极大地提高了AZ91D镁合金表面的耐腐蚀性能。
The composite coating was prepared on the surface of AZ91D magnesium alloy by arc spraying and thermal diffusion. The microstructure and phase structure of the composite coating were characterized by scanning electron microscopy, X-ray diffraction (XRD) and potentiodynamic polarization curve test. % Na Cl solution in the corrosion behavior of research and discussion. The results show that the AZ91D magnesium alloy sprayed aluminum coating obtained by solid state diffusion zinc coating uniform and dense composite coating, XRD results show that the coating is composed of Zn-Al intermetallic compounds Zn Al2O4, Mg2Zn11 and Al, Zn composition; The results show that the self-corrosion potential of the composite coating is shifting to -1.36V, which is about 230,130mV more positive than that of AZ91D magnesium alloy substrate and aluminum coating respectively. The self-corrosion current density of the composite coating is 4.7 × 10 -5A · cm-2, which is lower than the self-corrosion current density of 3.9 × 10-4A · cm-2. The results of potentiodynamic polarization test showed that the composite coating formed by this method greatly improved the corrosion resistance of AZ91D magnesium alloy.