Temporal series micrographs coupled with polarization curves to study pit formation under anodic polarization

This work presents the coupling of polarization curves and temporal series of in-situ micrographs during pit corrosion, thus allowing the current, the number of pits, and their area as a function of potential to be examined. Upon analyzing the data, it is possible to propose that the current slope changes are associated to the beginning of pit area growth without any change in their number. The pit potential is clearly correlated with the explosion in the number of pits. Finally, using the charge, the number of pits and their area, it was possible to estimate the mean pit depth and its growth law during the experiments.

► Pitting corrosion was investigated by coupled techniques. ► In situ optical microscopy allows to follow pit area and number. ► Polarization curve allows to follow current over the metal. ► Pitting potential is associated with an explosion in the number of pits. ► Crossing information from both techniques allows to estimate pit depth.