THE ATMOSPHERIC CORROSION OF IRON - A DISCUSSION OF THE PHYSICOCHEMICAL FUNDAMENTALS OF THIS OMNIPRESENT CORROSION PROCESS - INVITED REVIEW

In this review the physico-chemical fundamentals of the atmospheric corrosion of iron are discussed, as they result from a number of electrochemical and spectroscopic techniques, which have been applied in order to analyze the corrosion mechanism of the atmospheric corrosion during wet-dry-wet transitions. - After wetting a dry corroded metal surface the cathodic partial reaction of the corrosion process is given by the reduction of Fe3+- to Fe2+-states within the lattice of γ-FeOOH. If the corrosion potential is rather negative, then also magnetite is formed. As a consequence of the formation of Fe2+ states the electronic conductivity of oxide crystals close to the metal/oxide interface is increased. This results in an acceleration of the kinetics of the oxygen reduction.