In this study, laser-assisted plasma electrolytic oxidation (Laser/PEO) coating was prepared on AZ31B magnesium alloy for corrosion protection, due to insufficient corrosion protection caused by the inherent defects, cracks and poor quality of PEO coatings. The plasma discharge evolution, morphological characteristics, elemental composition during coating growth were characterized by high-speed camera, SEM, EDX, XRD and XPS, respectively. Meanwhile, Mott Schottky (M-S) curves, potentiodynamic polarization (PDP) curves and electrochemical impedance spectroscopy (EIS) tests characterized the oxygen vacancy defects and corrosion resistance of the coatings. The results demonstrated that laser-assisted irradiation not only induced plasma discharge on the anode surface, but also limited the plasma discharge size in the post-processing stage, which significantly increased the proportion of corrosion-resistant phase MgSiO (the proportion of MgSiO increased from 23.70% to 39.22%), thickness and density in the coating, and obviously reduced the oxygen vacancy defects and microcracks in the coating. As a result, the corrosion resistance of the Laser/PEO coating (9.29(±0.76)×10 A·cm) was further enhanced in comparation with the PEO coating (3.06(±0.19)×10 A·cm).

中文翻译：

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AZ31B镁合金激光辅助等离子体电解氧化(PEO)复合涂层的生长机理及耐蚀性能

【摘要】：针对AZ31B镁合金PEO涂层固有的缺陷、裂纹和质量差导致的腐蚀防护不足的问题,在AZ31B镁合金上制备激光辅助等离子体电解氧化(Laser/PEO)涂层进行腐蚀防护。分别采用高速相机、SEM、EDX、XRD 和 XPS 对涂层生长过程中的等离子体放电演化、形貌特征和元素组成进行了表征。同时，通过莫特肖特基（MS）曲线、动电位极化（PDP）曲线和电化学阻抗谱（EIS）测试表征了涂层的氧空位缺陷和耐腐蚀性能。结果表明，激光辅助辐照不仅在阳极表面引发等离子体放电，而且在后处理阶段限制了等离子体放电尺寸，使得耐腐蚀相MgSiO的比例显着增加（MgSiO的比例从23.70%~39.22%)，镀层厚度和致密性明显提高，镀层氧空位缺陷和微裂纹明显减少。结果，与PEO涂层（3.06（±0.19）×10 A·cm）相比，激光/PEO涂层（9.29（±0.76）×10 A·cm）的耐腐蚀性进一步增强。