Probing dynamic and localised corrosion processes on buried steel under coating disbondments of various geometries

摘要

A specially designed multi-electrode array has been utilised to visualise dynamic steel corrosion under disbonded coatings (CUD). The behaviour of CUD was found to be distinctively different under coating disbondments of different gap sizes and in saturated and non-saturated soils. In saturated soil, CUD behaved similarly as it usually does in electrolyte solutions, where CUD is mitigated by a cathodic protection induced high pH environment and a concentration polarisation mechanism. In non-saturated soil, CUD behaviour changed significantly with coating disbondment gap size. These observations have been explained by solution/soil distribution models proposed for coating disbondment of different geometries.