【摘要】 高Al含量(～2.3%，质量分数)再生镁合金由于含有较多第二相杂质而表现出较差的耐蚀性，因此往往需要对其进行表面处理才能进一步应用。本工作在高Al含量再生镁合金表面进行了一种新型微弧氧化(MAO)工艺处理，在未向电解液中引入任何颗粒的情况下，生成了水滑石膜层(LDH)，从而实现了一步制备得到MAO/LDH复合膜层。利用扫描电子显微镜和能谱仪，对合金基体和MAO处理后样品的表面及截面进行分析；利用电化学测试和析氢实验，表征基体和MAO处理后材料的耐蚀性能。结果表明，MAO层呈现出具有均匀元素分布特征的双层结构，MAO层沉积物表面呈现出典型LDH的规整纳米结构，MAO层厚度约为2.72μm，主要构成为MgO。LDH层厚度约为60 nm，富Mg、O、P、Al，经TEM分析确定其为Mg-Al LDH。利用本方法处理后的样品与裸基体相比表现出良好的耐蚀性，析氢速率相对于裸基体降低了约96.52%，自腐蚀电流密度降低了3个数量级。本文为镁合金表面一步法制备MAO/LDH复合膜层提供了一种可行的方案。更多还原

【Abstract】 Recycled Mg-alloys with high Al content(～2.3%) exhibit undesirable corrosion resistance due to their high second phase impurities, thus proper surface treatment is required for practical applications. In this work, a novel micro-arc oxidation(MAO) process was applied to a high-Al recycled Mg-alloy, while without introducing any extra particles into the electrolyte, a layered double hydroxide(LDH) film was formed, enabling the one-step fabrication of a MAO/LDH composite film. The surface and cross-sectional morphologies of the alloys with MAO/LDH film were analyzed using scanning electron microscopy(SEM) and energy-dispersive spectroscopy(EDS), and their corrosion performance was also assessed by electrochemical tests and hydrogen evolution measurement. It is revealed that the MAO/LDH composite layer exhibits a dual-layer structure with uniform elemental distribution. The inner MAO layer with a thickness of ～2.72 μm mainly consists of MgO whereas the outer layer, confirmed as Mg-Al LDH via TEM analysis, shows a thickness of ～60 nm, which is rich in Mg, O, P, and Al. Compared to the bare Mg-alloy, the MAO/LDH-coated Mg-alloy demonstrated significantly enhanced corrosion resistance: the hydrogen evolution rate was reduced by 28-fold, and the free-corrosion current density decreased by three orders of magnitude. This study provides a feasible strategy for one-step fabrication of MAO/LDH composite coatings on Mg-alloys, offering insights into improving the corrosion resistance of recycled Mg-alloys with high impurity content.更多还原