AM60压铸镁合金表面微弧氧化陶瓷层的耐蚀性电化学分析

Electrochemical Analysis of Corrosion Resistance of Micro-arc Oxidized Die-casting Magnesium Alloy AM60

为了探索AM60压铸镁合金微弧氧化陶瓷层的耐蚀性，采用IM6e型电化学工作站，测量了不同表面状态下制备10μm、20pm及30pm三种厚度微弧氧化陶瓷层在3．5％NaCl溶液中的电化学极化曲线，并对其进行了Tafel斜率分析。结果表明：微弧氧化处理，可以使AM60压铸镁合金的腐蚀电流密度降低2～4个数量级；压铸镁合金在原始表面状态下进行微弧氧化，其腐蚀电流密度随着处理厚度的增加而降低，厚度为30μm试样的腐蚀电流密度较低；对压铸镁合金处理前进行打磨，可以进一步降低腐蚀电流密度，在微弧氧化陶瓷层厚度为20μm时获得最低的腐蚀电流密度。

The effect of the surface state of micro-arc oxidation （MAO） films on corrosion resistance of die-casting AM60 Magnesium alloys in 3.5% NaCl solution was investigated by means of polarization curve measured with IM6e electrochemistry workstation. The thickness of MAO films samples was 10μm, 20μm and 30μm respectively. The Tafel slopes were analyzed. The results showed that the Icorr was decreased by a factor of 100 to 10000 times due to MAO treatment. The Icorr of samples decreased with the increase of thickness of the films, when the surface of samples was not polished. A lower Icorr could be obtained when the thickness of the films was 30μm The Icorr of oxide films could be decreased further more by surface polishing, and the lowest Icorr could be obtained when the thickness of the films was 20μm.