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为探索铬酸盐钝化膜提高锌镀层耐蚀性的机理和研究其发生黑变的初期腐蚀现象， 对电镀锌钢板黑变的动力学规律进行了研究。以湿热实验中镀锌层表面明度差随时间变化的关系来表征钝化和未钝化试片腐蚀的速度， 发现钝化后的镀锌层的腐蚀规律符合Ｗａｇｎｅｒ 方程， 未钝化的镀锌层的腐蚀规律符合对数方程， 并求出了相应的腐蚀反应的活化能。钝化使腐蚀反应的活化能提高了一个数量级以上。实验结果表明该腐蚀是由于氧的向内扩散和锌离子的向外扩散， 钝化膜的存在影响了腐蚀的历程。
In order to explore the mechanism of chromate passivation film to improve the corrosion resistance of zinc coating and study the initial blackening phenomenon, the kinetics of blackening of electrogalvanized steel was studied. The corrosion rate of passivated and unpassivated specimens was characterized by the relationship of brightness difference of galvanized surface with time in the wet heat test. It was found that the corrosion law of passivated galvanized coating accords with Wagner equation, unpassivated galvanized The corrosion law of the layer accords with the logarithmic equation, and the activation energy of the corresponding corrosion reaction is obtained. Passivation increases the activation energy of the corrosion reaction by more than an order of magnitude. The experimental results show that the corrosion is due to the inward diffusion of oxygen and the outward diffusion of zinc ions. The existence of passivation film influences the corrosion process.