Resolution of the apparent experimental discrepancies observed between SVET and SECM for the characterization of galvanic corrosion reactions

Abstract

A new approach for studying the local distribution of anodic and cathodic sites in a corroding system using the scanning vibrating electrode technique (SVET) and scanning electrochemical microscopy (SECM) is presented. When zinc is coupled to iron, dissolution of the active metal occurs in a localized manner (e.g., pitting corrosion), allowing for cathodic sites to be developed on zinc. Local alkalization and oxygen consumption related to cathodic activity are detected above portions of the zinc surface using SECM. Anionic fluxes related to the generation of OH− ions could be measured on the zinc surface outside the corroding pit by rastering the SVET probe closer to the substrate.