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构建了埋地管线钢在鹰潭土壤模拟溶液中的矩形缝隙剥离涂层模型,采用原位电化学测量方法对剥离区的X80钢进行电化学交流阻抗谱(EIS)表征,并对其腐蚀行为进行了研究.结果表明.腐蚀初期剥离区各位置的电化学反应特征相同、EIS由高频容抗弧和低频感抗弧组成.随着腐蚀反应进行,高频容抗弧半径增大.低频感抗弧消失.距漏点不同距离的X80钢试样的腐蚀程度有所区别:漏点处和剥离区底部的腐蚀最严重.为吸氧腐蚀和阳极溶解所致;剥离区中部腐蚀较弱,去除腐蚀产物的X80钢表面出现明显的点蚀坑,点蚀倾向加重,腐蚀类型由全面腐蚀向局部腐蚀转变.根据EIS规律和实验结果.剥离区的腐蚀进程可分为氧耗尽、阴离子迁移和腐蚀扩展3个阶段.
A rectangular slit peeling coating model of buried pipeline steel in Yingtan soil simulation solution was constructed. Electrochemical AC impedance spectroscopy (EIS) was used to characterize the X80 steel in the peeled zone by in-situ electrochemical measurement, and its corrosion behavior The results show that the electrochemical reaction characteristics of the stripping zone are the same at the initial stage of corrosion, and the EIS consists of a high-frequency capacitive reactance arc and a low-frequency inductive reactance arc.As the corrosion reaction proceeds, the high-frequency capacitive reactance arc increases and the low frequency inductive reactance arc disappears. X80 steel samples with different distances from the leak point have different degrees of corrosion: the leak point and the bottom of the stripping zone have the most serious corrosion, which is caused by oxygen absorption corrosion and anodic dissolution; the corrosion in the middle of the stripping zone is weak and the corrosion products are removed X80 steel surface pitting pits obvious pitting corrosion aggravate the type of corrosion from the full corrosion to local corrosion changes.According to the EIS law and experimental results in the stripping zone corrosion process can be divided into oxygen depletion, anion migration and corrosion expansion 3 A stage.