Evaluation of Corrosion Resistance of Organosilane/Fluorine Titanate Composite Passivation Film on Galvanized Steel Sheet and Analysis of Mechanism of Film-Formation and Corrosion Resistance

gamma -(2,3-glycidoxy) propyl trimethoxy silane (KH560) and gamma -methacryloxypropyl tri-methoxy silane (KH570) were mixed with fluorine titanate modified by 30% H(2)O(2) to afford a composite passivation fluid. Resultant fluid was then used for passivation of galvanized steel sheet. In the meantime, organosilane passivation film was also prepared on the steel surface for a comparative study. The molecular structure of as-prepared passivation films was analyzed by means of infrared spectrometry. Besides, the corrosion resistance of the passivation films was evaluated based on measurements of Tafel polarization curves and alternating current electrochemical impedance spectra as well as neutral salt-spray test and saline water immersion test. Results indicated that as-prepared organosilane/ fluorine titanate composite passivation film was more compact than the siliane passivation film, and the former possessed better corrosion resistance. After 72 h of salt-spray test, the surface of composite passivation film