交流干扰对剥离涂层下管线钢腐蚀行为的影响

摘要

The effects of AC interference on the corrosion behavior of X80 steel under disbonded coatings were investigated using electrochemical tests and corrosion morphology observation.The results showed that when there was no AC interference,with the prolongation of test time,only the self-corrosion potentials (Ecorr) of the samples at the damaged point and 4 cm away from the damaged point fluctuated slightly,and Ecorr of the samples far away from the damaged point had no change,and were basically in a stable state.After AC interference was applied,Ecorr of the samples shifted negatively with the increase of the AC interference voltage.The closer to the damaged point,the greater the influence of AC interference on the Ecorr of the samples.The corrosion current density (Jcorr) of the sample at each point first decreased and then increased,and the Jcorr of the sample at the damaged point changed greatly.AC interference increased the corrosion tendency and corrosion rate of the samples under the disbonded coating,and the corrosion rate of the sample at the damaged point was affected greatly,and the corrosion morphology was localized corrosion.%采用电化学试验和腐蚀形貌观察研究了交流干扰对剥离涂层下X80钢腐蚀行为的影响.结果表明:无交流干扰时,随着试验时间的延长,只有涂层破损点处及距离破损点4 cm处试样的自腐蚀电位出现了小幅波动,而远离破损点处试样的自腐蚀电位变化很小,基本处于稳定状态;腐蚀电流密度均有逐渐增大的趋势,且破损点处试样的腐蚀电流密度远远高于其他位置的.施加交流干扰后,随着交流干扰电压的增大,缝隙内金属的自腐蚀电位均有负移的趋势,且离破损点越近,试样的自腐蚀电位受交流干扰的影响越大,缝隙内各点试样的腐蚀电流密度均先减小后增大,破损点处试样的腐蚀电流密度变化较大.交流干扰增加了剥离涂层下试样的腐蚀倾向性及腐蚀速率,且破损点处试样的腐蚀速率受其影响较大,腐蚀形态为局部腐蚀.