交流电流密度对X70管道钢腐蚀行为的影响

为了研究交流干扰对埋地管道腐蚀行为的影响,通过失重法和电化学测量法相结合的方法,采用自行设计的交流干扰模拟装置进行室内试验,研究了不同交流干扰强度下X70钢在土壤模拟溶液中交流腐蚀行为的变化规律。通过对试验结果的分析,发现交流干扰下试样自腐蚀电位负向偏移,发生偏移原因为:给工作电极施加交流干扰,作用于电极反应上的法拉第电流相对于工作电极就是外加电流,会造成工作电极的极化,电极反应平衡被打破;腐蚀速率随交流电流密度增大而增大;交流腐蚀产物外层为疏松状的红棕色Fe_2O_3和棕黄色Fe_2O_3·H_2O,内层为黑色的Fe_3O_4,根据电极反应和腐蚀产物组成对交流腐蚀过程进行了推导。

Impact of Alternating Current Density on Corrosion Behavior of X70 Pipeline Steel

Combining weight-loss method with electrochemical measure nethod,the indoor simulation experiments were carried out by the selfdesigned alternating interference simulation device,and the change rule of alternating corrosion behavior of X70 steel in NS4 solution under alternating interference of different intensity was investigated.Moreover,by analyzing experimental results,it was discovered that there was negative offset of free corrosion potential of samples under alternating interference.The reason was shown as follows.When alternating interference was imposed to the working electrode,faradic current working on the electrode reaction was impressed current relative to the working electrode,which would polarize the working electrode and break the balance of the electrode reaction.Besides,corrosion rate increased with the increase of density of alternating current.In addition,the fa(c)ade of alternating corrosion products was loose,reddish brown Fe3O4 and brown Fe2O3 · H2O,and the interior of alternating corrosion products was black Fe3O4.At last,according to electrode reaction and composition of corrosion products,the process of alternating corrosion was derived.