Porous magnesium oxide (MgO) ceramic layers were prepared on AZ31 magnesium alloy via microarc oxidation (MAO) and sustained hydrothermal treatment at 90°C for 18 h in alkaline zinc nitrate solution with varying Al³⁺ concentrations. Increasing the Al³⁺ concentration advanced the formation of layered double hydroxide (LDH) films on the MgO ceramic layers, enabling the sealing of micropoles and cracks via in situ growing. Electrochemical and immersion test results indicated that the MAO/hydrothermal treatment‐prepared LDH/MgO composite coatings achieved increased corrosion resistance than single MAO ceramic layers, due to the sealing effect and ion‐exchange capacity of LDHs. Furthermore, as Al³⁺ concentration in hydrothermal solution increased, the anticorrosion properties of the composite coatings were enhanced. Concludingly, LDH/MgO composite coatings could provide augmented long‐term anticorrosion protection for magnesium alloys compared with single MAO ceramic layers.

中文翻译：

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水热溶液中Al3 +浓度对AZ31镁合金上MgO陶瓷层微结构和耐蚀性能的影响

通过微弧氧化（MAO）在AZ31镁合金上制备多孔氧化镁（MgO）陶瓷层，并在Al ³⁺浓度不同的碱性硝酸锌溶液中于90°C持续水热处理18 h 。Al ³⁺浓度的增加促进了MgO陶瓷层上层状双氢氧化物（LDH）膜的形成，从而可以通过原位生长来密封微极和裂纹。电化学和浸没测试结果表明，由于LDH的密封作用和离子交换能力，与单层MAO陶瓷层相比，MAO /水热处理制备的LDH / MgO复合涂层具有更高的耐腐蚀性。此外，作为Al ³⁺随着热液浓度的增加，复合涂层的防腐性能增强。最后，与单个MAO陶瓷层相比，LDH / MgO复合涂层可以为镁合金提供增强的长期防腐保护。