Electropolishing Mechanism of Ti-6Al-4V Alloy Fabricated by Selective Laser Melting

摘要

In this study, the electropolishing mechanism of Ti-6Al-4V alloy fabricated by selective laser meltingwas analysed by using the electrolyte of perchloric acid and glacial acetic acid. The influences ofelectropolishing time on the surface morphology and corrosion performance of the Ti-6Al-4Al alloywere investigated, with regard to the surface morphology, chemical compositions and corrosionbehaviours, using scanning electron microscopy, atomic force microscopy, X-ray photoelectronspectroscopy, potentiodynamic polarization and electrochemical impedance spectroscopy. The resultsshow that after electrochemical polishing, the surface of the Ti-6Al-4V alloy was covered with a thinlayer of oxide film composed of titanium, aluminium and vanadium oxides. The surface roughness ofthe Ti-6Al-4V alloy with an electropolishing time of 15 min was at its minimum, reaching an idealpolishing effect. The electropolishing mechanism of the Ti-6Al-4V alloy was the shedding of sphericalparticles on the alloy surface and the smoothing of prominent parts under the electrochemical reaction.As the electropolishing time increased, the corrosion resistance of the Ti-6Al-4V alloy in Ringer’ssolution initially increased then decreased. The increment in VOx content and oxidation of unstableand low-valence TiO, or Ti2O3 into stable and compact TiO2 in the oxide film triggered by prolongingpolishing time were found to enhance corrosion resistance.