Corrosion protection of mild steel by coating with TiO2 thin films co-doped with NiO and ZrO2 in acidic chloride environments

A series of TiO2 thin films co-doped with NiO and ZrO2 coatings was prepared by sol-gel and dip-coating techniques for the corrosion protection of mild steel substrates. The crystalline phase, morphology and composition of the coatings were achieved by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDAX) and fourier transform infrared spectroscopy (FTIR). Texture properties of prepared coated samples were investigated by N-2 adsorption-desorption isotherms. The corrosion protection performance was investigated in 3.5% NaCl + 1.0 M HCl solution by electrochemical impedance spectroscopy and potentiodynamic measurements. Results show that, the prepared coatings offer good anti-corrosion protection to mild steel in the studied acidic chloride solution, with the degree of protection depending on number of coating layers (thickness) and co-dopant content in the coatings. SEM/EDAX investigations reinforce the possibility of protecting mild steel against corrosion through the formation of a protective layer of NiO/TiO2 and co-doped NiO-ZrO2/TiO2 using coatings. (C) 2016 Elsevier B.V. All rights reserved.