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

Abstract

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 N2 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.