Some microelectrochemical methods for the investigation of passivity and corrosion

Abstract

Abstract Microelectrochemical approaches using a microcapillary cell (MCC), scanning electrochemical microscopy (SECM), and in situ ellipsomicroscopy for studying heterogeneous passive or corroding surfaces of materials are reviewed. An MCC can be used to investigate the localized behavior of a site of interest on a material by various electrochemical methods, including electrochemical impedance spectroscopy. SECM has often been used for imaging corroding surfaces or passive films on materials. Moreover, the use of a liquid-phase ion gun, a mode of SECM that forms a local aggressive environment at the solution/material interphase, can reveal the depassivation mechanism and kinetics of the surface of a material. The heterogeneous growth or degradation of a thin passive film on a material has been monitored using in situ ellipsomicroscopy, and a depassivation site has been successfully found before a film breakdown is initiated. These microelectrochemical methods are useful for monitoring the heterogeneous distribution of a passive film and for investigating the heterogeneity of the passivity of materials.