Effect of processing time on microstructure of surface and corrosion resistance of coatings resulting from plasma electrolytic oxidation on titanium alloy in hydroxyapatite nano-particles electrolyte

This study investigated the effect of coating processing time on the microstructure of surface and corrosion resistance of coatings resulting from Plasma Electrolytic Oxidation (PEO) on the substrate of TiAl6V4 alloy. The coating processes in hydroxyapatite nano-powder electrolytic were carried out under the condition of constant voltage of 600 V and three different times of 125, 250, and 350 seconds. Studying the microstructure of coatings identified that the coating formed in 125 (s) had a more compact and steady structure with fine surface cavities and less porosity. The X-ray diffraction pattern of coating demonstrates that this coating consists of oxide phases of titanium (rutile and anatase) and hydroxyapatite. Moreover, the study of corrosion resistance of coatings by potentiodyna.mic polarization and electrochemical impedance spectroscopy in corrosive solution of chloride sodium 3.5% showed that the coating formed in 125 s had the most significant corrosion resistance potential and the least I-Corr and, thus, the highest resistance to corrosion. (C) 2020 Sharif University of Technology. All rights reserved.