不同添加剂对镀锌层钼酸盐钝化膜腐蚀电化学性能的影响

Effect of Additives on Electrochemical Behavior of Molybdate Passivation Film on Galvanizing Coating

利用塔菲尔(Tafel)极化曲线和电化学交流阻抗谱,研究了不同添加剂单乙醇胺、硝酸铈、植酸和羟己叉基二膦酸对镀锌层钼酸盐钝化膜腐蚀电化学性能的影响,并与加速腐蚀试验结果进行了对比。结果表明,添加剂的加入明显改变了钝化膜层的自腐蚀电位,使钼酸盐钝化膜的耐腐蚀性明显增强,且钝化膜的阻抗谱呈明显单一的容抗弧,腐蚀过程受电化学控制。

Tafel polarization curves and electrochemical impedance spectra (EIS) were recorded to investigate the effect of several additives including mono ethanol amine, cerium nitrate, plant acid, and hydroxy sub-hexyl diphosphine acid on the electrochemical behavior of molybdate passivation film on galvanizing coating. The electrochemical test results were compared with those of accelerated corrosion test as well. It was found that the introduction of the additives led to obvious change in the open-circuit potential and significant increase in the corrosion resistance of the molybdate passivation film. Moreover, the electrochemical impedance spectra of the passivation films showed single capacity arc line, indicating that the corresponding corrosion processes were controlled by electrochemical step.