The effect of concentration and source of calcium ions on anticorrosion properties of Ca-doped TiO2 bioactive sol-gel coatings

Titanium dioxide (TiO2) coating with an enhanced anticorrosion properties and bioactivity was developed by doping it with calcium ions through a sol-gel method. The effect of annealing temperature, anions, as well as calcium ions concentration on microstructural and anticorrosion properties of Ca-doped TiO2 coatings have been investigated. The phase composition and morphology of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The corrosion resistance of M30NW biomedical alloy coated with Ca-doped TiO2 coatings was evaluated using electrochemical methods in conditions similar to the normal physiological environments (PBS solution, pH 7.4, temperature of 37 °C). The obtained results show that the annealing temperature and the source of calcium ions influence the anticorrosion properties of Ca-doped TiO2 coatings. The best anticorrosion properties were registered for coatings with the highest concentration of Ca ions. At the same time all the examined coatings presented good bioactivity in SBF solution test.