In-situ synthesis and characterization of CeO2-TiO2 composite coatings on titanium substrate by micro-arc oxidation

Ceramic coatings were fabricated on titanium substrate by the micro-arc oxidation (MAO) treatment in compound electrolyte with different Ce(NO3)(3) contents (0, 1, 2, 3, and 4 g/L). To analyze the microstructure, phase structure, and elemental composition of the MAO coatings, scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS) were employed. The results displayed that the porous coatings were mainly composed of TiO2 and CeO2 from Ce(NO3)(3) in the electrolyte. As the concentration of Ce(NO3)(3) increased, the average thickness and density of the ceramic coatings increased obviously. The adhesion of the MAO coatings to the substrate increased firstly and then decreased. The electrochemical tests and cavitation experiments were applied to evaluate the corrosion resistance of the samples before and after MAO treatment. The optimal corrosion resistance was obtained when the concentration of Ce(NO3)(3) was 2 g/L in polarization cure and cavitation erosion tests. These results indicated that the MAO coatings with different Ce(NO3)(3) concentrations provide preferable protection for titanium substrate. Finally, the formation mechanism of the CeO2-TiO2 composite MAO coatings was proposed.