目的 在镁合金表面制备磷酸盐-高锰酸盐化学转化膜，以提高镁合金的耐蚀性能。方法 以磷酸盐与高锰酸盐为转化处理液，在镁合金表面制备出化学转化膜，进而采用SEM、EDAX、XRD及电化学测试方法研究了转化温度、转化液pH值和转化时间对转化膜形貌、成分、厚度、结构和耐蚀性的影响。结果 磷酸盐-高锰酸盐转化膜呈深紫色，由Mg、P、Mn和O元素组成，膜层表面存在网状裂纹，厚度为4~18 μm，转化膜的耐蚀性随转化温度、pH值、转化时间的增加呈现先增加后降低的变化规律。结论 磷酸盐-高锰酸盐转化膜由镁的磷酸盐组成。磷酸盐-高锰酸盐转化处理的最佳工艺条件为：转化温度40 ℃，转化液pH=3.5和转化时间15 min。经磷酸盐-高锰酸盐化学转化处理后，镁合金的耐蚀性能得到了明显的提高。

The work aims to improve the corrosion resistance of magnesium alloy by preparing phosphate-permanganate conversion coating on the surface of magnesium alloy. The chemical conversion coating on the surface of magnesium alloy was prepared with phosphate-permanganate as conversion electrolyte. Effects of conversion temperature, pH value and conversion time on the surface morphology, chemical composition, thickness, structure and corrosion resistance of the conversion coating were studied by scanning electron microscopy (SEM), energy dispersion analyzer of X-ray (EDAX), X-ray diffraction (XRD) and electrochemical test. The phosphate-permanganate conversion coating was dark violet and 4~18 μm thick. It consisted of Mg, P, Mn and O elements with purple appearance and micro cracks. The corrosion resistance of conversion coating first increased and then decreased as the conversion temperature, pH value and conversion time increased. The phosphate- permanganate conversion coating is composed of magnesium phosphate. Optimum processing conditions are as follows: conversion temperature of 40 ℃, pH value of 3.5 and conversion time of 20 min. After chemical conversion treatment by phosphate-permanganate conversion electrolyte, the corrosion resistance of magnesium alloy is greatly improved.