Deposition and Characterization of a New Mixed Organic/Inorganic Cerium Containing Coating for the Corrosion Protection of Eletrogalvanized Steel

Protective coatings have been deposited on electrogalvanized steel by immersion in solutions containing 2-Butyne-1.4-diol propoxylate (C7H11O3), cerium nitrate, sodium nitrate and sodium sulphate for different immersion periods. The surface morphology and chemical composition of the coatings formed on the electrogalvanized steel were studied using field emission gun scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier Transform Infrared Spectroscopy. The corrosion resistance of the electrogalvanized steel prior to and after surface treatment was investigated by electrochemical impedance spectroscopy in 0.1 mol L-1 NaCl solution. The results were compared to the performance of a chromate conversion coating in the same solution. The coatings formed on the electrogalvanized steel surface showed the presence of a mixed organic/inorganic layer containing Ce2O3 and CeO2 which improved the corrosion resistance of the substrate and showed a superior corrosion resistance to that provided by a chromate conversion coating.