剥离涂层下X70钢阴极极化效果试验研究

Experimental Study of Cathodic Polarization Effect on X70 Steel Under Disbonded Coating

在总结现有国内外相关研究试验装置与试验研究方法的基础上,自行设计组装了新的试验装置,该试验装置能够较好地模拟工程实际中发生轴向涂层缺陷的埋地管道的腐蚀介质环境;同时通过开路电位测试,针对模拟破损、剥离涂层下的金属基体,就通电点通电、调压、断电、断电后再通电过程中表面的电位分布进行了试验研究。结果表明,阴极极化的增大在一定程度上增大缝隙深处极化效果的同时,也增大了缝隙内部的电位梯度;此外,阴极保护停运会造成缝隙内部金属短时间内腐蚀的发生,以及阴极保护再启动后阴极极化效果的降低。

The experimental apparatus required in this study was designed,based on the study of the relative experimental apparatus and the experimental methods used at home and abroad.The corrosive environment of the metal substrate under disbonded coatings was simulated well with the designed experimental apparatus.The distribution changes of the potentials on the working electrode surfaces during the periods of energizing,voltage regulating,power failure,energizing after power failure were studied by open circuit potential testing and surface observing.The results showed that the increase of cathodic polatization can increase not only the polarization effect in the deep of crevice,but also the potential gradient along the crevice.During the period of cathodic protection outage,corrosion would happen in a short time,and the protective effect would decline when cathodic protection restarted.