镁合金微弧氧化陶瓷层耐蚀性的电化学分析

ELECTROCHEMICAL ANALYSES OF CORROSION RESISTANCE OF MAGNESIUM ALLOY (MB8) TREATED BY MICRO-ARC OXIDIZATION

采用IM6e型电化学工作站,测试了镁合金微弧氧化后陶瓷层的电化学阻抗(EIS)、稳态电流/电位极化曲线(SteadyStateI/ERecording)以及Tafel斜率。结合测量结果对微弧氧化处理镁合金的耐蚀性进行分析。结果表明,经过微弧氧化处理后试样的电化学阻抗比未经处理原始试样的电化学阻抗高3个数量级。微弧氧化处理过程中存在一个最佳陶瓷层厚度,当超过或低于这个最佳厚度时,试样的耐蚀性都较差,只有达到这个最佳厚度时,试样的耐蚀性才是最佳的。

Electrochemical Workstation IM6e was used to measure the electrochemical impedance, steady state I-E polarization curves and Tafel slope of ceramic layer made by micro-arc oxidization of the magnesium alloy (MB8). The results showed that after the treatment of micro-arc oxidization the electrochemical impedance of the sample increased by 1000 times than that of the untreated sample. During the treatment of micro-arc oxidization, there was a best thickness of ceramic layer. As the thickness of ceramic layer was more or less than the best thickness, the corrosion resistance of the sample was rather poor. The sample showed the best corrosion resistance at the best thickness.