Comparing Strategies to Probe Self-Healing of Defects in Coated Metals

摘要

The self-healing ability of anticorrosive coatings has become an important issue, particularly among systems that line-up as substitutes to chromate based anticorrosive systems. Different ways are being experimented to probe self-healing properties but in many cases it is difficult to distinguish whether true self-healing conferred by the coating, or just passivity phenomena due to addition of inhibitors to the solution, is taking place. Moreover, the experimental protocols used to check self-healing in new systems were not tested with systems known to have self-healing properties. In this work we compare different strategies to check the self-healing of defects in new systems (namely hybrid sol-gel coatings on aluminium alloys) and in commercial chromate-containing coatings, systems generally accepted to possess self-healing ability. The experimental techniques used were electrochemical impedance spectroscopy and micro-electrochemical techniques including the scanning vibrating electrode technique.