2018 Volume 67 Issue 1 Pages 41-49
Recently, the authors reported the improved corrosion resistance of the electro-galvanized steel coated with epoxy resin organic layers by the simultaneous additions of flaky Al and particulate Ni powders for the use in fuel tanks. In order to understand the roles of Ni and Al powders in the coatings on the corrosion behavior of the coated electro-galvanized steel, the electro-galvanized steel was coated with epoxy resin layers containing either Ni or Al powders, and their corrosion behavior was examined by the corrosion immersion tests in aqueous solution containing formic acid, acetic acid and NaCl, potentiodynamic polarization measurements, electrochemical impedance spectroscopy （EIS）, and oxygen gas and water vapor permeation measurements. Both Ni and Al powders in the organic coatings accelerated the corrosion. The potentiodynamic polarization curves disclosed the increased anodic and cathodic currents and the EIS study showed the reduced coating resistance by the addition of Ni or Al powders. Findings in this study suggested that the improved corrosion resistance of the coatings containing both Al and Ni powders were not simply explained by the corrosion behavior of the coated steel containing only Ni or Al powders and a possible synergistic effect of Ni and Al powders in improving the corrosion resistance is discussed.