Electrochemical Corrosion Theory

Abstract

The driving force for corrosion is the potential difference developed by the corrosion cell

$${{E}_{\text{cell}}}=E_{\text{red}}^{\text{cat}}-E_{\text{red}}^{\text{anode}}$$

(2-17)

However, the cell potential does not correctly predict the corrosion rate, and it is the corrosion rate that is the essential determiner of a metal’s suitability in a corrosive environment. Logically, if the cell potential is small, the corrosion rate will be low. On the other hand, a large cell potential does not necessarily mean that the metal must corrode badly. It may passivate, for example, and corrode at an extremely low rate.