Potential Dependence of Localized Corrosion in Iron

Two passivating potentials, E_F1 and E_F2, can be observed for iron in chloride containing media. From the existence of these two passivating potentials the existence of two breakdown potentials follows: the first breakdown potential, E_b1, and the second breakdown potential E_b2. In the regions immediately positive to these potentials, the rate of localized corrosion (that is, the total current density and the number of pits) rises exponentially with the potential. According to the solution composition, the current density in the pits is potential independent or obeys the exponential dependence.