Real‐time monitoring of the degradation of metallic and organic coatings using electrical resistance sensors

摘要

>The development of new metallic coatings to protect steel, as well as the optimization of maintenance operations on site requires obtaining relevant corrosion data as function of the exposure conditions. In atmospheric and aggressive environments such as under accelerated corrosion tests or in coastal zones, electrical resistance (ER) sensors have demonstrated their ability to provide relevant real‐time corrosion data. Among the sensors commercially available, only single material such as steel, zinc, copper are proposed. However, even if this allows obtaining interesting corrosion data for such reference materials, these data are not representative of industrial systems, such as galvanized steel. Indeed, zinc‐based coatings can contain different alloying elements, e.g., aluminum and magnesium, which impact drastically their resistance to corrosion. In addition, with single material sensors, the influence of the galvanic coupling between the coating and the substrate, in the presence of a defect or a cut edge is not considered. In this study, hot dip galvanized, electrogalvanized, and painted steel ER sensors are exposed in accelerated corrosion tests. The results show that this method is very promising to (i) detect the red rust apparition; (ii) assess the corrosion resistance of industrial zinc and organic coatings; and (iii) obtain relevant data in real‐time along the exposure time.