Synthesis and corrosion resistance of SiO2-TiO2-ZrO2-Bi2O3 coatings spin-coated on Ti6Al4V alloy

Abstract

This report shows the synthesis and corrosion resistance of SiO2-TiO2-ZrO2-Bi2O3 coatings deposited by means of spin-coating on Ti6Al4V alloy. The sols were prepared from a mixture of organic precursors, tetraethoxysilane (TEOS) 98%, titanium tetrabutoxide (TBT) 97%, Zirconium (IV) butoxide (TBZ) 80% in 1-butanol solution, and bismuth nitrate pentahydrate Bi (NO3)3 * 5H2O. The coatings were evaluated via potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in an electrolytic solution of 3.5% wt NaCl + 0.5 M H2SO4. The rheology and pH of the prepared sols were studied through rheology, pH as a function of time, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) analysis. The coatings were characterized via X-ray diffraction (XRD), scanning electron microscopy equipped with dispersive energy spectroscopy (SEMEDX), X-ray fluorescence (XRF), and adhesion measurements. The results showed that the films add good corrosion resistance to the metal substrate, decreasing current densities up to one order of magnitude.