冷轧带钢电解清洗极板腐蚀机理和原因

采用线性电位扫描法研究了碳钢在不同脱脂剂浓度下的阳极极化过程，进一步研究了碳钢在不同不同脱脂剂浓度条件下、不同电位下的恒电位、恒电流电解行为，在此基础上对生产现场进行了考察。电化学实验表明：碳钢阳极极化过程依次经历活化区、钝化区、过钝化区及极限区；活化区基体活化溶解电流小，不影响电极寿命；过钝化区电极表面开始发生析氧反应；极限区析氧反应达到极限，使基体腐蚀反应大量发生，电极寿命降低；脱脂剂浓度越低、阳极电位越高，电极表面基体溶解反应速率越大，相应电极使用寿命越短。实际生产中，极板表面由于电流分布不均使其局部电流超过极限电流导致局部腐蚀发生，而电解槽内极板安装精度、电极表面气泡无法逸出、极板表面污泥淤积等都均会影响电流分布。

Analysis of corrosion mechanism and reason of electrode plates used in electrolytic cleaning to cold rolled strip

Anodic polarization process of carbon steel in alkali solution was studied by linear potential scan,and electrolysis behavior was also analyzed under differential alkali concentration and electric potential by electrolysis at constant potential and current test.On this basis,the production site was inspected.Electrochemical experiments showed anodic polarization process of carbon steel in solution included activated region,passive region,transpassive region,and terminal region.Matrix dissolution current was small,does not affect electrode life in active region.Oxygen evolution reaction occurred on electrode plates in transpassive region.Dissolution reaction of matrix would start in terminal region caused by limit of oxygen evolution reaction which resulting in short- lived of electrode plates.The lower the concentration of the degreasing agent,the higher the potential of the anode,the greater the dissolution of the electrode surface of the substrate the reaction rate,the shorter the service life of the electrode.A high incidence of localized corrosion occurred due to localized current exceeding limited current which was resulted by uneven current distribution,and installed inaccurate of plate in electrolytic cell will influences distribution of current but also hardly escape of bubble on the electrode surface and sludge depositing on the electrode plates.