Low temperature titania coatings for aluminium corrosion protection.

TiO2 coatings on AA6082 aluminium alloy were obtained at low temperature (80 and 100 °C) by sol-gel dip coating technique starting from titanium tetra-isopropoxide solution in ethyl alcohol, in presence of acetic acid with both functions of catalyst and chelating agent. The curing temperatures used for these coatings are extremely interesting and make such coatings suitable to incorporate additives such as organic inhibitors or nano particles. The coated samples were characterized by Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM/EDS), Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Electrochemical Impedance Spectroscopy (EIS). Compact coatings with a thickness of 500 nm consisting of amorphous and nearly stoichiometric titanium dioxide were obtained. EIS results revealed an effective corrosion protection of the substrate for more than 150 hours of immersion in 3.5 wt% NaCl aqueous solution