Distinction between general and pitting corrosion based on the nonlinear dynamical response of passive iron surfaces perturbed chemically by halides

We report on different types of current oscillations induced by fluoride and chloride species in the Fe|H2SO4 electrochemical system. On the basis of the nonlinear dynamical response of the system, certain criteria are deduced, which allow the distinction between general and pitting corrosion. We use a point defect model (PDM) for the description of the iron oxide film along with the formation of surface complexes between the oxide iron cations and halides in order to explain the difference between general and pitting corrosion.