摘要
油气管道采用涂层和阴极保护的方法防止腐蚀,涂层破损剥离处会形成微腐蚀环境,引起管线钢发生腐蚀事故。基于微电极技术研究X80钢在剥离涂层下的腐蚀行为,测量了不同阴极保护电位下X80钢在剥离涂层下NS4溶液中的局部开路电位、电化学阻抗谱和线性极化电阻。不外加阴极保护时,开口处电位最高,电荷转移电阻和线性极化电阻最小,腐蚀速率最快;外加-870 mV阴极保护电位时,开口处电位最低,试件未受到腐蚀,缝隙中间部位的电荷转移电阻和线性极化电阻较高,缝隙底部未受到阴极保护,腐蚀速率最快;外加-1000 mV阴极保护电位时,随着距开口距离的增大,电位正向移动,电荷转移电阻和线性极化电阻增大,缝隙内处于过保护状态。阴极保护电位不足时,试件在缝隙开口到底部的腐蚀行为存在差异性,增大阴极保护电位可使缝隙内免受腐蚀,但阴极保护电位过高会使缝隙内处于过保护状态。
Oil and gas pipelines use coating and cathodic protection methods to prevent corrosion,and a micro⁃corrosive environment will be formed where the coating is damaged and peeled off,causing pipeline steel corrosion accidents.The corrosion behavior of X80 steel under the disbonded coating was studied based on the microelectrode technique,and the local open circuit potential(OCP),electrochemical impedance spectroscopy(EIS)and the linear polarization impedance of X80 steel were measured in NS4 solution under the disbonded coating with differ⁃ent cathodic protection potentials.Results showed that when no cathodic protection was applied,the potential at the opening was the highest,the charge transfer resistance and linear polarization impedance were the smallest,and the corrosion rate was the fastest.When the cathodic protection potential of-870 mV was applied,the potential at the opening was the lowest and was not corroded,and the charge transfer resist⁃ance and linear polarization impedance were high in the middle of the gap and were not corroded,the bottom of the gap was not subjected to ca⁃thodic protection,and the corrosion rate was the fastest.When the cathodic protection potential of-1000 mV was applied,as the distance from the opening increased,the potential moved forward,the charge transfer resistance and linear polarization resistance increased,and the gap was over⁃protected state.When the cathodic protection potential was insufficient,the corrosion behavior of the specimen from the opening to the bottom of the gap was different.Besides,increasing the cathodic protection potential could prevent corrosion in the gap,but too high cathodic protection potential caused the gap in an over⁃protection state.
作者
胡正阳
孙东旭
马贵阳
刘超广
朱文浩
HU Zhengyang;SUN Dongxu;MA Guiyang;LIU Chaoguang;ZHU Wenhao(Key Laboratory of Oil and Gas Storage and Transportation Engineering in Liaoning Province,School of Petroleum and Natural Gas Engineering,Liaoning University of Petroleum and Chemical Technology,Fushun 113001,China)
出处
《材料保护》
CAS
CSCD
2023年第12期79-89,117,共12页
Materials Protection
基金
辽宁石油化工大学博士科研启动基金(2020XJJL⁃013)资助。
关键词
X80钢
剥离涂层
NS4溶液
腐蚀
阴极保护
X80 steel
disbonded coating
NS4 solution
corrosion
cathodic protection
