Evaluation of the behaviour of particulate polymeric coatings in a corrosive environment. Influence of the concentration of metal particles

In this work pretreated steel specimens were coated by a spinning process with particulate polymeric composites consisting of an epoxy resin (DOW 331) and iron powder. Applied coatings were roughly 70 μm thick and the contained quantity of iron particles was varied (7.5, 15, 30% wt./wt.). The effect of the presence of iron particles in the coatings as well as the influence of their concentration on the evaluation of the coatings' behaviour in a corrosive environment (3.5% NaCI) was studied. Electrochemical impedance spectroscopy, corrosion potential, corrosion current density (Tafel) and dielectric measurements were performed. Minor differences in the anticorrosive behaviour of the coatings were observed irrespective of the iron content in the coating. Effective resistance inhibition action of the composite coatings was diminished with the increase of exposure time to the corrosive environment being in all cases very close to that of the pure epoxy resin coating