Scanning microelectrochemical characterization of the effect of polarization on the localized corrosion of 304 stainless steel in chloride solution

Abstract

Corrosion processes occurring on stainless steel 304 surfaces under anodic polarization have been characterized using scanning electrochemical microscopy (SECM) and the scanning vibrating electrode technique (SVET), complemented with conventional potentiodynamic polarization curves. Stable pit formation has been detected by SVET on the samples as result of surface modification under electrochemical control, which may include the previous electrochemical reduction of passive oxide layer if the media is not aggressive enough to induce pitting at small overpotentials. Additionally, the sample generation – tip collection operation mode of the SECM has enabled the detection of local release of iron (II) ions, as well as their conversion to iron (III), both processes being greatly affected by the potential applied to the substrate