Design of Ti-6Al-4V alloy surface properties by galvanostatic electrochemical treatment in a deep eutectic solvent Ethaline

This study demonstrates the possibility of the design of Ti-6Al-4V alloy surface properties by galvanostatic electrochemical treatment in a deep eutectic solvent Ethaline (a eutectic mixture of choline chloride and ethylene glycol in molar ratio 1:2, respectively) at the temperature of 25 °C. A short-time anodic treatment in Ethaline in a wide range of current densities (2–50 mA cm−2) provides formation of surface oxide films with controllable chemical composition, roughness and wettability, improved corrosion resistance and with biologically-inspired topography. It was found that a unique feature of this electrolyte in comparison with traditional acidic ones is that oxidation is not observed during electrochemical processing of titanium alloy. It was shown that formation of microrough structure on Ti-6Al-4V alloy surfaces is observed at relatively low current densities (2–15 mA cm−2) of the electrochemical treatment; formation of nanorough structure occurs at higher current densities (20–50 mA cm−2). It was found that all treated samples did not demonstrate any cytotoxic effect and have good cells adhesion and cells viabilities. Bacterial resistance of Ti-6Al-4V alloy samples can be controllably adjusted and increased by the surface leveling in Ethaline at high current densities.