FREQUENCY AND TIME-RESOLVED MEASUREMENTS AT ROTATING-RING-DISK ELECTRODES FOR STUDYING LOCALIZED CORROSION

By conferring frequency and time resolution of the rotating ring-disk electrode technique, original information can be obtained on the mecha nism of corrosion processes involving the formation of intermediate, p assive, or corrosion product layers. The methodology that allows the m easurement of the actual flux of chemical species generated by a local ized corrosion site is described which takes into account the usual pa rameters of RRDE and the location of the active spot on the disk surfa ce. Application to pitting corrosion of iron by Cl- in sulfuric and ph osphoric acids reveals important features of the early transient event s in the pit life.