Technology and Corrosion Inhibition Properties of Mo-Ce Composite Passivation Films on Galvanized Sheet

The corrosion resistance of passive films was examined by Pb(Ac)2 titration test.Studied by L18(37) orthogonal test and single factor tests,the optimal composite passivation technology of molybdate and cerium salt is: passivation solution concentration 8 g/L,pH 6,passivation time 90 s,passivation temperature 45 ℃,drying time 65 min,drying temperature 30 ℃,raw material mole ratio 1∶1.5.Under the optimal conditions the Pb(Ac)2 titration test could achieve 40s.Electrochemical polarization curves and electrochemical impendence spectroscopy showed that the composite passivation film could improve the corrosion resistance of zinc coating and single cerium salt or molybdate salt conversion films markedly,mostly due to the influence on the anodic reactions in the corrosion process.