AZ31镁合金的电化学腐蚀行为

Electrochemical Corrosion Behaviors of AZ31 Magnesium Alloys

采用阳极极化和电化学阻抗谱(EIS)技术研究了AZ31镁合金的电化学腐蚀行为.阳极极化结果表明:AZ31镁合金在中性NaCl溶液中发生活化溶解,随Cl-浓度增加,腐蚀速率增加;在不同pH溶液中,随pH值增大发生由活化溶解向自钝化的转变,临界值为pH=10.5.电化学阻抗谱结果表明:在Ecorr-100 mV电位下,阻抗谱由单一容抗弧组成,等效电路为Rs(QRt),表征析氢反应过程;在Ecorr电位和Ecorr+100 mV电位下,阻抗谱由高频容抗弧和低频感抗弧组成,等效电路为Rs(QRt(LRL)),感抗弧的出现表明电极反应过程中存在中间产物Mg+.

The electrochemical behavior of AZ31 Mg alloy was investigated by measuring, anodic polarization curves and electrochemical impedance spectroscopy（EIS）. The results of anodic polarization indicated that AZ31 alloy dissolves in the NaC1 solutions with pH of 7, and corrosion rates of the AZ31 Mg alloy increase with C1^- concentrations. In different pH values solutions, the transformation from the active dissolution to the passivation is taken place for AZ31 Mg alloy at a critical pH value of 10.5. At a cathodic potential, the EIS shows only a capacitive loop in the high frequency range accounts for hydrogen evolution, and the equal circuit is Rs （QRt）. At the corrosion potential and an anodic potential, the EIS consists of two loops, one capacitive in the high frequency range and another inductive in the low frequency range ＇which indicates intermediate products Mg^＋ , and the equal circuit is Rs （ QRt （LRL） ）.