Corrosion Resistance of in-Situ Phosphatizing Organic Coating Modified with Rare Earth Oxide Nanoparticles

In-situ phosphatizing organic coating is a one-step self-phosphatizing process, in which the formation of metal phosphate layer on the substrate surface and the curing of organic paint coating take place simultaneously, instead of multi-step metal pretreatment process. In the present research, the impact of three rare earth oxide nanoparticles on corrosion resistance of in-situ phosphatizing organic coatings formed on 6061-T6 aluminum alloy was investigated by polarization curve and electrochemical impedance spectroscopy (EIS). The results indicated that the small amounts of rare earth oxide nanoparticles can effectively improve the corrosion resistance of the in-situ phosphatizing organic coating in 3.5%NaCl solution. The influencing degree of rare earth oxide nanoparticles on the corrosion resistance of the in-situ phosphatizing organic coating follows the order of lanthanum oxide > yttrium oxide < cerium oxide nanoparticles.