Numerical Simulation of Transient Process for Corrosion Environment in Coating Crevice with Cathodic Protection

Potential, current distributions, the chemical and electrochemical environment in crevice are simulated by transient mathematical model for the system of coating crevices in NaCl solution with cathodic protection. The results indicated that the potential in crevice increases in positive direction and the total current density decreases, pH value in crevice rises monotonously at first and then reduces, but the chloride ion concentration decreases at first and then increases, oxygen concentration of solution reduces gradually and then tends to uniformity and conductivity enhances at first and then reduces with the increasing of crevice length. With the prolonging of polarization times, the potential in crevice decreases in negative direction, the total current density tends to uniformity; pH value in crevice rises and the chloride ion concentration decreases gradually, but oxygen concentration of solution reduces and conductivity enhances gradually. The comparing results between the theoretical and experimental data indicated that the mathematical model described transient process for corrosion environment with cathodic protection is feasible.