Rare Earth Cerium Passivation Technology of Galvanized Steel

The technology of rare earth cerium conversion coating for galvanized steel was studied by a single factor experiment to get the optimized passivation parameters when the concentration of Ce(NO3) was 30 g·L-1, H2O2 was 20 mL·L-1, pH=3.5 and passivated at 40℃ for 60s. The corrosion resistance was examined by weight loss test, neutral salt spray test and electrochemical impedance spectroscopy. The results showed that the corrosion impedance of the pretreated sample was significantly improved, the corrosion rate was decreased by one order of magnitude, and the anti-white rust time was 46h. Scanning electron microscopy (SEM) observation showed that the conversion coating covered the surface of zinc compactly.