INFLUENCE OF SILANE γ-APS PRE-FILM ON PASSIVATION OF GALVANIZED STEEL BY RARE EARTH LANTHANUM
硅烷γ-APS协同稀土镧钝化镀锌钢板的研究

The sample of galvanized steel was firstly coated with a thin self-assembled monolayer of silane (γ-APS)and then immersed in a rare earth solution to get a complex coating. The corrosion resistance of which was studied by means of electrochemical impedance spectroscopy and neutral salt spray.The results showed that the pre-coating of silane improved the corrosion resistance of the sample significantly.Atomic force microscope observation showed that the complex coating was much uniform and denser. Analysis results of X-ray energy dispersive spectroscopy showed that the complex coating was composed of N,O,Si,Fe,Zn,La,and the relative mole fraction of La of the complex coating was nearly three times higher than that of the single rare earth coating.The results also shown that the silane pre-coating was beneficial to the deposition of rare earth coating,the silane had a synergistic effect with the rare earth coating,therewith improved the anticorrosion performance of the complex coating.The formation and the corrosion protection mechanism of the complex coating were discussed.