Electropolishing and Mirror-like Preparation of Titanium in Choline Chloride-Ethylene Glycol Mixture Liquid

This report presents simple, rapid and an efficient electropolishing of Ti metal in choline chloride-based ionic liquid (so called Ethaline) at 20 °C. This electrolyte is relatively benign and environmentally friendly which is desirable for electropolishing. Potentiostatic method was applied to Ti electropolishing in this electrolyte. Under an electrochemical condition of 6–10 V for 30 min. and at 20 °C, a promising electropolishing process was performed without obvious gas evolution. To characterize the electropolished surface, atomic force microscope (AFM) and scanning electron microscope (SEM) were used. The achieved an apparent mirror-like finished surface with an average surface roughness (Ra) was 5.7 nm which is considerably different from that of unpolished one (Ra = 118.8 nm). The microscopic results showed leveling and brightening of the surface of Ti by carrying out the current procedure. This electrolyte provides sufficient environment to dominate the mass transport mechanism which is responsible for reduction in the surface roughness.