Investigation on corrosion behaviour of polymeric coatings on weathering steel under 3.5% NaCl Solution

Abstract

Abstract Construction of columns and bridges for sea transportation, where corrosion resistance is a major factor, is the most common use of weathering steel, it is a low carbon alloy steel. Under the correct environmental circumstances, weathering steel develops an adherent protective coating on its surface. Patina is the protective layer that develops on the surface of weathering steel. It protects against further corrosion occurring to the structure. Since these weathering steels are repeatedly exposed to a wet environment, their corrosion resistance decreases. Our research focuses on investigations of the coatings used on weathering steel to increase its corrosion resistance in marine conditions. The coatings applied on the substrate were poly urea, polyurethane, epoxy and black enamel. Immersion test, salt spray test and potentio-dynamic test were performed on the coated samples to determine how they would react to various conditions. The depth of the corrosion on the coatings was confirmed by the profilometry test. Based on corrosion tests, the conclusion that polyurea is the best coating, followed by polyurethane, black enamel, and epoxy, based on the corrosion studies.