Occurrence of Salt Films during Initiation and Growth of Corrosion Pits

Abstract

The purpose of this investigation is to employ simple transport laws to gain a perspective of events which occur during early stages of pit initiation and growth. The initiation of pits on the surface of passive metals undoubtedly occurs at flaws in the passive surface film. At the moment of pit initiation, the flaws would be expected to be very small, on the order of the passive film thickneses. Calculations indicate that the current density to such small regions would tend to be exceedingly high and that a salt film is therefore likely to form at very early stages of initiation of pit growth.