The Role of Polarization In Electrochemical Corrosion^★

In its most practical aspects as well as in its fundamental mechanisms electrochemical corrosion is almost always associated with irreversible electrode phenomena. The multitude of factors involved in these phenomena may be defined as electrochemical polarization. Idealized schematic as well as actual polarization diagrams are discussed. Methods of correlating polarization with corrosion data such as weight loss are shown. A method for obtaining the contribution made by the polarization of each electrode reaction to the total polarization observed at an electrode is described along with the implications thereof in the evaluation of the true over-voltage values. In addition, other factors which may fall within a broad definition of polarization are treated. The relationship of the so-called IR drop or true ohmic resistance at metal liquid interfaces to polarization diagrams and to voltage concepts is discussed.