Introduction and Discussion of Cathodic Protection Mechanisms

Three cathodic protection mechanisms are introduced in detail, including mitigation of anodic dissolution, immunity and passivation. The deficiencies in these mechanisms are expounded. It is point out that the “open circuit potential” in the theory of mitigation of anodic dissolution should be “equilibrium electrode potential”, and the mechanism of immunity is similar to the mechamism of mitigation of anodic dissolution. In view of the doubts about the passivation mechanism of cathodic protection, it is still necessary to evaluate the applicability of the mechanism through the study of metal surface state and interface characteristics between metal and electrolyte under cathodic protection.