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

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.