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通过电弧喷涂/电火花沉积复合工艺在AZ91D镁合金表面制备了耐蚀性涂层。利用扫描电镜(SEM)、能谱分析仪(EDS)、电化学测试和浸泡实验等研究手段,研究了电弧喷涂/电火花沉积复合涂层的结构及耐腐蚀性能,并对涂层腐蚀机制进行了分析。结果表明:经电弧喷涂/电火花沉积复合处理后,E corr=-1.33 V,较基体和喷涂铝涂层试样分别正移约280,40 mV,腐蚀倾向性有所降低;点蚀电位为-0.704 V,较电弧喷涂铝涂层试样提高约60 mV,点蚀敏感性有所降低;电弧喷涂铝涂层试样的钝化电流i pass=4.6×10-3A·cm-2,电弧喷涂/电火花沉积处理试样的ipass=3.2×10-5A·cm-2,经电火花表面改性后,涂层钝化膜自修复能力大幅增强;在3.5%NaCl溶液中,经36 h浸泡试验后,电弧喷涂铝涂层试样表面出现直径达150μm的点蚀坑;而电弧喷涂/电火花沉积复合涂层表面仅出现直径约5~8μm的点蚀坑,涂层发生的主要为亚稳态点蚀。
The corrosion resistant coating was prepared on the surface of AZ91D magnesium alloy by arc spraying / EDM composite process. The structure and corrosion resistance of arc spraying / EDM composite coating were studied by means of scanning electron microscope (SEM), energy dispersive spectrometer (EDS), electrochemical test and immersion test. The corrosion mechanism of coating was also studied Analysis. The results show that the E corr = -1.33 V after the arc spraying / EDM treatment is about 280 and 40 mV more positive than that of the substrate and the sprayed aluminum coating, respectively. The corrosion potential decreases -0.704 V, which is about 60 mV higher than that of the arc-sprayed aluminum coating. The pitting sensitivity is reduced. The passivated current ipass = 4.6 × 10 -3 A · cm -2 of the arc-sprayed aluminum coating, The ipass = 3.2 × 10-5A · cm-2 after spraying / EDM treatment showed that the self-healing ability of the passivation film was greatly improved by EDM. In 3.5% NaCl solution, after 36 h After the immersion test, the pitting pits with a diameter of 150μm appeared on the surface of the arc-sprayed aluminum coating samples. However, the pitting pits with the diameter of about 5 ~ 8μm appeared on the surface of the arc spraying / EDM composite coating. Metastable Pitting.