Performance Assessment of Differently Dried Coating Systems for Potential Application in the Power Transformer Industry

Many companies in the power transformer industry are striving to speed up the drying process of coatings, which is why alternative drying methods are constantly being explored while maintaining the same coating protection properties. The infrared (IR) drying of protective coatings is a potential solution for their higher productivity, but has not yet been extensively investigated. In this paper, two solvent-borne coating systems, with and without zinc in the primer, from two different manufacturers, dried by infrared radiation and under atmospheric conditions, were studied. The coating systems consisted of epoxy primer, epoxy intermediate coat, and polyurethane topcoat. Anti-corrosion performance of the coatings was characterized using a salt spray chamber, pull-off adhesion testing, electrochemical impedance spectroscopy (EIS) investigation, and open circuit potential (OCP) measurement. All samples were analyzed using stereo microscope. A scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDX) for detailed study and chemical composition determination was used. The results showed that infrared technology notably reduced coating drying times while maintaining or improving anticorrosion performance properties compared to the coatings dried under atmospheric conditions.