Study of silane modified polyaniline coatings electropolymerized on zinc electroplated steel sheet

The effects of silane on the formation of polyaniline coatings electropolymerized on zinc-electroplated steel sheet have been investigated by chronopotentiometry technique. The morphology and thickness of polyaniline coatings are measured by SEM. Corrosion behaviors of chromating films and polyaniline coatings in 3.5% NaCl solution are studied by salt spray test and electrochemical impedance spectroscopy (EIS) method. Experimental results show that the anticorrosion properties of polyaniline coatings are close to that of chromating film because of its good shielding and inhibiting properties. From the FTIR and XPS data, the following conclusions can be obtained: (1) The doping level for the polyaniline films modified by 7-APS is increased and the oxidation level is reduced comparing with polyaniline films without modification, which are f 1% and 64% respectively; (2)There are four chemical environment: C-Si-O-Si, C-Sr-OH, C-Si-O-C, C-Si-O-Zn.