目的 进一步提高Mg-Gd-Y-Zr合金微弧氧化涂层的耐腐蚀性能。方法 采用超高频微弧氧化技术在含有Al2O3纳米颗粒的溶液中制备了微弧氧化涂层。利用扫描电子显微镜(FESEM)、能谱仪(EDS)和X射线衍射仪(XRD)对微弧氧化涂层的表面形貌、截面形貌、成分和晶体结构进行分析。利用极化曲线和电化学阻抗谱(EIS)测试了涂层的耐腐蚀性能。结果 频率由0.5 kHz提升至20 kHz后，涂层表面放电孔洞面积由0.07~24.4 μm²降低至0.08~6.3 μm²，涂层的孔隙率由6.47%减小至3.35%。Al2O3纳米颗粒的添加使超高频涂层表面形成大量自封闭孔洞结构，进而进一步降低了涂层表面的孔径面积(0.1~ 4.63 μm²)和孔隙率(0.97%)。极化试验表明，提高频率至20 kHz，涂层的自腐蚀电流密度由4.7×10^?6 A/cm²降低至4.7×10^?7 A/cm² ，添加 Al2O3纳米颗粒，涂层的自腐蚀电流密度进一步降低至1.7×10^?7 A/cm²，表明其耐蚀性能显著提高。阻抗谱显示，20 kHz-Al涂层具有最大的阻抗，说明该工艺可有效提高微弧氧化涂层的耐蚀性能。 结论 超高频可有效降低放电孔洞尺寸，提高微弧氧化涂层的致密性，改善涂层的耐腐蚀性能。超高频与Al2O3纳米粒子的协同作用使涂层表面形成自封闭孔洞结构，进一步提高微弧氧化涂层的致密性和耐腐蚀性能。

Microarc oxidation (MAO) is a kind of technology that causes partial plasma discharge by applying high voltage to melt metal oxides and form ceramic coatings on light metal (aluminum, magnesium and titanium) and their alloys with the thickness of tens of microns to hundreds of microns, which have the advantages of wear resistance, corrosion resistance, electrical insulation, etc. Due to the inherent plasma discharge phenomenon in the MAO discharge process, the discharge gas and molten metal oxide will be ejected from the inside of the coating. During the ejecting process, defects such as discharge channels and micro-cracks are formed under the rapid quenching effect in the aqueous solution. This defect structure has a high specific surface area and can serve as a penetration channel for the corrosive medium, affecting the overall corrosion resistance of the MAO coating. Therefore, avoiding or sealing these discharge channels is crucial for improving the corrosion resistance of coatings and enhancing the large-scale application of light alloys.