Evaluation of the Synergetic Effect of MIO and Aluminum Flake Pigments on Coating Resistance by EIS and Salt Spray

Anti-corrosive pigments are added to coatings to improve the coating resistance against corrosion. Electrochemical impedance spectroscopy(EIS) and salt spray are two common methods for evaluation of the anticorrosion performance of coatings. In this study, a mixture of aluminum flake and micaceous iron oxide pigments with different proportions were employed in epoxy based coatings and their corrosion resistances were studied with EIS and salt spray tests. The alignment of the pigments was evaluated with a scanning electron microscope (SEM). The results indicated that the alignment of the pigments is an important factor in anticorrosive performance of the coatings and although both of the pigments individually have a considerable effect on the improvement of the anti-corrosive performance of the coatings, but when a mixture of the pigments was employed the results were better than each of them singly. The best corrosion resistance was observed in the sample which the ratio of the aluminum pigment to MIO pigment was 9 to 1. J. Color Sci. Tech. 1(2009), 227-236.© Institute for Colorants, Paint and Coatings.