CORROSÃO LOCALIZADA DO ALUMÍNIO EM MEIOS AERADOS E EM MEIOS COM BAIXO TEOR OXIGÊNIO: ESTUDO E COMPARAÇÃO POR MEIO DE CURVAS DE POLARIZAÇÃO

LOCALIZED CORROSION OF ALUMINUM IN AERATED ENVIRONMENTS AND IN ENVIRONMENTS WITH LOW OXYGEN CONTENT: STUDY AND COMPARISON THROUGH POLARIZATION CURVES. In this study, the influence of deaeration on the electrochemical behavior of aluminum was studied by polarization techniques. The advantages of deaeration for the evaluation of localized corrosion on aluminum are discussed. The influence of the corrosive environment with low oxygen contents on the electrochemical response of aluminum was evaluated by anodic and cathodic potentiodynamic polarization curves. The polarization tests were carried out in chloride solutions followed by optical and scanning electron microscopy characterization. It was observed that deaeration of the solution significantly influences the electrochemical behavior of aluminum, as predicted by corrosion kinetics theories. For the cathodic curves, a decrease in the limiting current density for the oxygen reduction reaction (ORR) was observed for low oxygen solutions, while the “apparent” initiation of the hydrogen evolution reaction (HER) was shifted to higher potentials. In the anodic curves, a common passive behavior was not observed in aerated conditions, however, at the corrosion potential, localized pitting was observed indicating that the material was already above the breakdown potential (Ebr). In the low oxygen content solution, however, a passive region with a breakdown potential, was observed on the anodic curves.