含缺陷涂层X80钢热影响区的电化学阻抗分析

为了进一步探讨X80钢涂层缺陷对耐土壤腐蚀性能及使用寿命的影响,将有无涂层缺陷的X80钢浸泡在玉门土壤模拟溶液中,采用电化学方法分析了其电化学阻抗谱。结果表明:无缺陷涂层的X80钢具有良好的防腐蚀效果;线缺陷涂层在不同测试期内的阻抗谱曲线都呈现为具有2个时间常数的双容抗弧特征;存在涂层缺陷时,外界腐蚀性介质会到达基体,使之腐蚀,随着腐蚀时间的延长,腐蚀产物会在缺陷处堆积;阴极反应形成的OH-增加会促使局部碱性环境的形成,进而导致X80钢涂层与基体界面剥离,发生缝隙腐蚀。

Electrochemical Impedance Spectroscopy Analysis of Heat-Affected Zone of X80 Steel with Coating Defect

The electrochemical impedance spectroscopy (EIS) and corrosion immersion test of the coating specimen on X80 steel in Yumen simulated soil solution were conducted.Results showed that the coating specimen without defects performed excellent corrosion inhibition performance.The electrochemical impedance spectroscopy of the coating with line defects presented double capacitive arc with two time constants.When the surface defects existed in the coating,the external corrosion medium could diffuse to the interface between coating and steel substrate,which led to corrosion.As the corrosion time extended,the corrosion products would accumulate in the defects.Furthermore,the increase of OH-caused by cathodic reaction could induce the formation of local alkaline environment,which resulted in the peeling of interface between coating and substrate and promoting the crevice corrosion.