目的 提高镁合金微弧氧化膜层的耐蚀性。方法 在锆盐体系电解液中对AZ91D镁合金进行微弧氧化处理，通过调节二次电压对AZ91D镁合金微弧氧化膜层的孔隙进行封闭，采用XRD、SEM和电化学测试分别对微弧氧化膜层的物相、表面形貌和耐蚀性进行了研究。结果 二次电压对膜层的相成分没有影响，主要相组成为MgO、MgF2、ZrO2、Mg2Zr5O12。随着二次电压的升高，膜层表面放电微孔孔径先减小后增大，孔隙率先降低后升高。与没有二次电压相比，施加二次电压的腐蚀电流降低2~3个数量级，极化电阻升高1~2个数量级，耐蚀性明显提高，且当二次电压为160 V时，膜层的极化电阻最高，耐蚀性最好。结论 二次电压能够对AZ91D镁合金微弧氧化膜层的孔隙进行封闭，进而阻止腐蚀液通过微孔进入基体，提高膜层的耐蚀性。

The work aims to improve corrosion resistance of micro-arc oxide film of magnesium alloy. Micro-arc oxidization was performed to AZ91D magnesium alloy, and holes in micro-arc oxide film of AZ91D magnesium alloy were sealed by adjusting secondary voltage. Phase, surface morphology and corrosion resistance of the micro-arc oxide film were investigated by means of XRD, SEM and electrochemical test. The film was mainly composed of MgO, MgF2, ZrO2 and Mg2Zr5O12, which were not affected by the secondary voltage. With the increase of secondary voltage, diameter and porosity of discharge micropores on the film first decreased and then increased. Compared with that not subject to secondary voltage, corrosion current decreased by 2~3 orders of magnitude, polarization resistance increased by 1~2 orders of magnitude and corrosion resistance improved significantly when the secondary voltage was applied. At the secondary voltage of 160 V, polarization resistance of the film was the highest and the corrosion resistance was the best. Secondary voltage can seal the pores in micro-arc oxide film of AZ91D magnesium alloy to prevent corrosive liquid from entering into the substrate through micropores and improve corrosion resistance of the film.