摘要
目的明确交流杂散电流对埋地管线防腐层剥离和破损处防腐层下腐蚀的影响规律及其导致防腐层剥离的作用机理。方法通过基于COMSOL Multiphysics有限元仿真、交流阻抗谱分析及三维体式显微镜观测等方法,研究在格尔木土壤模拟溶液中,交流杂散电流干扰下,X70钢表面3PE防腐层剥离处的防腐层下腐蚀及剥离机理。结果由于防腐层破损点和剥离区域的存在,使得防腐层的防护性能明显降低,交流杂散电流在初始预留剥离处的X70钢表面呈不均匀分布,破损点处所分布电流密度明显高于剥离区边缘处。杂散电流引起的腐蚀反应主要集中在防腐层破损点处,而处于预留剥离区域下方的X70钢表现出缝隙腐蚀的现象。防腐层破损点处的腐蚀坑深度随电流密度的增加而逐渐变深,而当交流电流密度由0A/m^2增加到100 A/m^2时,防腐层剥离面积明显增大,此后,当电流密度继续增大,剥离面积基本保持不变。当施加的交流电流密度相同时,随着防腐层剥离面积的减小,杂散电流造成的防腐层剥离面积增大,X70钢试样上的最大腐蚀坑略微加深。结论造成防腐层剥离的交流杂散电流存在临界电流密度值,使得防腐层剥离面积达到最大且之后保持不变。防腐层初始剥离面积较小时,交流电所造成的X70钢腐蚀及防腐层剥离行为更为严重。
The work aims to clarify the influence of stray alternating current(AC)on the corrosion under the anticorrosive coating caused by peeling and damage of buried steel pipeline corrosion coating and the mechanism of action leading to peeling of coating.COMSOL Multiphysics simulations,AC impedance spectroscopy analysis and three-dimensional microscope were used to study the corrosion mechanism and stripping behavior of X70 high-strength pipeline steel at 3PE coating stripping under AC stray current in Golmud soil simulation solution.The protective performance of the coating was significantly reduced due to the presence of damage points and stripping areas in the coating.The stray current was unevenly distributed on the surface of X70 steel in the initial reserved stripping area,and the current density at the breakage point was significantly higher than that at the edge of the stripping area.The corrosion reaction caused by stray currents was mainly concentrated at the damage point of the coating,while the X70 steel under the reserved peeling zone showed crevice corrosion phenomenon.Corrosion pit depth at the damage point of the coating gradually became deeper as the current density increased,but when the AC current density increased from 0 A/m2 to 100 A/m2,the peeling area of the anti-corrosion coating increased significantly.After that,when the current density continued to increase,the peeling area remained basically unchanged.When the applied alternating current density was the same,the peeling area of the anti-corrosion layer increased as the peeling area of the reserved anti-corrosion layer decreased,and the maximum corrosion pit on the X70 steel sample slightly deepened.There is a critical current density in the delamination area of coatings caused by AC stray currents and such density can result in and keep maximum stripping area.When the initial stripping area of coating is smaller,corrosion and coating stripping of X70 steel caused by AC stray current are more serious.
作者
王新华
王祖全
陈迎春
宋旭婷
徐成
WANG Xin-hua;WANG Zu-quan;CHEN Ying-chun;SONG Xu-ting;XU Cheng(School of Mechanical Engineering and Applied Electronics Technology,Beijing University of Technology,Beijing 100124,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2018年第11期142-150,共9页
Surface Technology
基金
国家自然科学基金(51471011)
北京工业大学"日新人才"培养计划~~
关键词
交流杂散电流
X70管线钢
防腐层剥离
缝隙腐蚀
临界电流密度
AC stray current
X70 pipeline steel
coating delamination
crevice corrosion
critical current density
