直流干扰对X80管线钢表面腐蚀行为的实验研究

为探究直流电流密度对X80管线钢的表面腐蚀行为,采用传统三电极体系与直流干扰源相结合的方式,建立了不同直流电流密度下X80管线钢在近中性NS4土壤模拟溶液中的电化学测试体系,得到了X80管线钢自腐蚀电位、极化曲线、电化学阻抗和腐蚀形貌特征。结果表明,直流电流密度对X80管线钢在NS4溶液中的腐蚀行为主要分为两个阶段:第一阶段为iDC=0~20 mA/cm^2时,此时主要为双电层和扩散层的形成过程,以全面腐蚀为主,腐蚀电流密度随直流电流密度的增大而增大,腐蚀产物主要为FeOOH;第二阶段为iDC≥50 mA/cm^2时,此时主要以点蚀为主,腐蚀电流密度基本不变,内层腐蚀产物主要以黑色Fe3O4为主。

Experimental Study on Surface Corrosion Behavior of X80 Pipeline Steel Influenced by Direct Current Interference

In order to explore the surface corrosion behavior of X80 pipeline steel caused by direct current(DC)density,the electrochemical test system of X80 pipeline steel in neutral soil simulated solution under different DC density is established by combining the traditional three-electrode and DC interference source,and the self-corrosion potential,polarization curve,electrochemical impedance and corrosion morphology characteristics of X80 pipeline steel are obtained.The results show that the corrosion behavior of X80 pipeline steel caused by DC density in NS4 solution is mainly divided into two stages.In the first stage,iDC=0~20 mA/cm^2,the stage is mainly the formation process of double electric layer and diffusion layer,and general corrosion plays the leading role.At this time,the corrosion current density increases with the increase of direct current density,and the corrosion product of the inner layer is mainly FeOOH.In the second stage,iDC≥50 mA/cm^2,pitting corrosion is the main corrosion and current density is basically unchanged,and black Fe3O4 is the main corrosion product in the inner layer.