AZ31镁合金在Na2SO4溶液中的电化学腐蚀行为

将AZ31镁合金在pH6.1的0.1mol/L Na2 SO4溶液中长时间浸泡,利用X射线衍射(XRD)和扫描电子显微镜(SEM)分析不同浸泡时间腐蚀产物膜的相结构和形貌变化；利用阳极极化和电化学交流阻抗谱(EIS)测量技术研究AZ31镁合金腐蚀产物膜的形成过程及浸泡时间对合金耐蚀性能的影响规律.研究结果表明:AZ31镁合金在0.1mol/L NaSO4溶液中可形成固态的多孔氧化膜,腐蚀产物膜主要由MgSO4组成；随着浸泡时间的延长,腐蚀产物膜在合金表面的覆盖率和厚度逐渐增加,阳极极化曲线呈现类似于自钝化的现象,且自腐蚀电位逐渐升高,腐蚀电流密度减小,表明腐蚀产物膜对基体具有一定的保护作用；腐蚀产物成膜过程中的EIS均呈现两个容抗弧,具有两个时间常数,两个容抗弧的直径均随浸泡时间的增加而增大,同时相位角平台变宽,相位角提高,说明腐蚀产物膜的厚度越厚,对阻碍反应离子向基体扩散和迁移的影响越大.

Electrochemical Corrosion Behavior of AZ31 Magnesium Alloy in Na2 SO4 Solution

The microstructure and surface morphology of corrosion product films formed on a AZ31 magnesium alloy in 0.1 mol·L-1 Na 2 SO 4 solutions with pH 6.1 are studied by X-ray diffraction and scanning electron microscopy.The electrochemical corrosion behaviors of the AZ31 magnesium alloy is estimated by using anodic polarization measurements and electrochemical impedance spectroscopy.The results show that the porous corrosion product film of AZ31 magnesium alloy is consisted of MgSO 4.The anodic polarization curve of the corrosion product films shows self passivation-localized corrosion,and the self-corrosion current density I corr decreases compared with the original AZ31 magnesium alloy.The EIS of corrosion product films show two capacitive arcs.With prolonging immertion time,the diameters of the capacitive increase and the flat roof of the phase angle is broaden with increasing phase angle.