CORROSION POTENTIAL2

"The corrosion is a spontaneous, dynamic phenomena with electrode reactions taking place and a current flowing. Consequently, both reactions are polarized and their potentials approach each other; as a matter of fact, they must become equal to preserve a single potential for the metal. However, the two reactions are not necessarily equally polarized. The overpotential of the two electrode reactions will be generally different, and their values will be dictated by the requirement that the electrode potentials be equal (at the ""corrosion potential"") at one, uniquely defined current (the corrosion current). See the Tafel equation for a relation between overpotential and current. (The ir drops in the solution and the metal are ignored in the above discussion, this is justified by the close proximity of the anodic and cathodic areas on the corroding metal.) "