Effect of Procedure Time on Microstructure and Corrosion Behavior of ZrTiO4/ZrO2 Nanocomposite Coatings by Plasma Electrolytic Oxidation (PEO) Applied on the Ti-6Al-4V Substrate

Abstract

In this research, the effect of PEO procedure time on the distinct properties of coatings such as morphology, chemical composition, roughness and corrosion has been studied. A scanning electron microscopy equipped with an energy dispersive spectroscopy was used to study the microstructure of the coatings. In addition, x-ray diffraction (XRD) and roughness meter were used to evaluate the chemical composition and roughness of the coatings, respectively. The corrosion properties of coatings have been also studied by polarization and electrochemical impedance experiments in the Hank's physiological solution. The results of microstructural analysis showed that rising the time of the coating procedure resulted in an increase in the size of porosity, thickness and roughness. The results of the XRD pattern showed that all coatings were composed of two phases of zirconia and zirconium titanate and that the change in time of coating did not alter the chemical composition of the coating. In the case of corrosion resistance of coatings, the most corrosion potential (611 mV) with the least corrosion current density (18.50 nA/cm²) in the coating created at the end of the third step of coating (10 minutes) resulted in the most corrosion resistance (0.602 MΩ.cm²).