ABSTRACT To improve the corrosion resistance of the ceramic layer prepared by micro-arc oxidation (MAO) on magnesium alloy, a hydrophobic Mg-Al-Co layered double hydroxide (LDH) coating was fabricated on MAO coated AZ31 magnesium (Mg) alloy by using a simple in-situ growth method. The results showed that the LDH film covered the MAO coating tightly, and it sealed the micro-pores and cracks in the MAO coating successfully. As a result, the LDH film increased the water contact angle of MAO coating from 10.35° to ∼137.21°, and the hydrophobic LDH/MAO composite coating increased the E corr of MAO coating from –1.47 to –1.39 V/SCE and decreased the I corr by about two orders of magnitude. The electrochemical impedance spectroscopy results showed that the LDH/MAO composite coating achieved the largest dimension of capacitive loop and the highest impedance at low frequency compared to MAO coated and uncoated AZ31 Mg alloy. Therefore, the LDH/MAO composite coating could provide long-term protection for Mg substrate from corrosive environment due to its hydrophobic function, ion-exchange ability and barrier effect. This work has significant meaning to the applications of Mg alloys. GRAPHICAL ABSTRACT

中文翻译：

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Mg-Al-Co层状双氢氧化物涂层提高微弧氧化陶瓷层的耐蚀性

摘要 为了提高镁合金微弧氧化（MAO）制备的陶瓷层的耐腐蚀性能，在微弧氧化（MAO）涂层的 AZ31 镁（Mg）合金上制备了疏水性 Mg-Al-Co 层状双氢氧化物（LDH）涂层。一种简单的原位生长方法。结果表明，LDH薄膜紧密地覆盖了MAO涂层，成功地封闭了MAO涂层中的微孔和裂缝。结果，LDH 膜将 MAO 涂层的水接触角从 10.35° 增加到~137.21°，疏水性 LDH/MAO 复合涂层将 MAO 涂层的 E corr 从 –1.47 V/SCE 增加到 –1.39 V/SCE 并降低了我纠正了大约两个数量级。电化学阻抗谱结果表明，与MAO涂层和未涂层​​的AZ31镁合金相比，LDH/MAO复合涂层实现了最大尺寸的电容回路和最高的低频阻抗。因此，LDH/MAO复合涂层由于其疏水功能、离子交换能力和阻隔作用，可以为镁基体提供长期的腐蚀环境保护。该工作对镁合金的应用具有重要意义。图形概要