Monitoring local spatial distribution of Mg2+, pH and ionic currents

Micro ion-selective electrode techniques can analyze concentration of particular ions at the solid-liquid interface from the side of solution being an alternative, or a complement, to methods based on potential and current changes across the interface. We report the successful application of ion-selective micro-electrodes for mapping local activity of Mg2+ and H+ (by scanning ion-selective electrode technique, SIET) as well as local ionic current density measurements (by scanning vibrating electrode technique, SVET) over the surface of Mg-based alloy in aqueous chloride-containing solution. The local concentration of Mg2+ ions dissolved due to corrosion from artificial defects and pH changes together with cathodic and anodic currents are measured by combination of two selective and one vibrating microelectrodes. Combination of these techniques in one experiment gives a powerful tool for investigation mechanisms and kinetics of electrochemical corrosion processes in micro-confined zones. (c) 2007 Elsevier B.V. All rights reserved.