Visualising dynamic passivation and localised corrosion processes occurring on buried steel surfaces under the effect of anodic transients

• A new method for visualising dynamic electrode processes is presented.
• The method is illustrated by measuring buried steel corrosion under anodic transients.
• The temporal and spatial resolutions of the wire beam electrode are demonstrated.
• A critical anodic transient duration is noted as the period for local depassivation.

A new method of visualising dynamically changing electrode processes has been demonstrated by mapping localised corrosion processes occurring on buried steel surfaces under the effect of anodic transients. Dynamically shifting external electrical interferences such as anodic transients are known to affect the efficiency of cathodic protection (CP) of underground pipelines; however unfortunately conventional techniques including electrochemical methods have difficulties in measuring such effects. In this paper we report that the wire beam electrode has necessary temporal and spatial resolutions required for measuring and visualising the dynamic effects of anodic transients on CP, passivation and localised corrosion processes occurring on buried steel surfaces. For the first time a critical anodic transient duration has been observed and explained as the incubation period for the breakdown of passivity and the initiation of localised corrosion.