ABSTRACT
Abstract-Hydrolyzed silanes of the type (HO)3Si(CH2)3Y(CH2)3Si(OH)3, in which Y is a functional group, are water-soluble, ionized molecules, so it should be possible to deposit them on metals by electrodeposition. Various combinations of silane mixtures were tested at different voltages, pH values, bath concentrations and exposure times on panels of aluminum alloys. The corrosion resistance of silane-coated aluminum panels was investigated by DC polarization and electrochemical impedance spectroscopy techniques. The thickness of the silane films was measured by ellipsometry. Electrodeposition results in a more organized and uniform silane film with less porosity as compared to immersed films. The layer formed at the interface between the silane film and the metal oxide has a high ohmic resistance and low permeability to electrolyte. Especially the resistance to pitting corrosion is improved by the electrodeposition process as compared to the dipping process.
