Dry and wet corrosion behaviour of AISI 304 stainless steel coated by sol-gel ZrO2-CeO2 films

ZrO2-CeO2 coatings were deposited on 304 stainless steel substrates by dip coating in alkoxide solution. The coatings were transparent and continuous at thicknesses below about 700 nm. The films were used as barriers against oxidation for 304 stainless steel at high temperature. The best performance (no oxidation up to 16 h at 750 degrees C) was obtained with a coating approximately 1 mu m thick. The corrosion resistance of the coated samples in an aggressive electrolyte (15 wt.% HCl solution) was studied by electrochemical impedance spectroscopy, a technique frequently used to test the protective properties of organic and metallic coatings on metals. The protective action of the deposited coatings was discussed as a function of the film thickness and quality.