Electropolishing with Low Mass Loss for Additive Manufacturing of Ti6Al4V in Zinc Chloride-Urea Deep-Eutectic Solvent

Abstract

A novel electropolishing approach for Ti6Al4V was developed involving a zinc chloride (ZnCl2)-urea deep-eutectic polishing system, with current density of 0.6 A cm−2, temperature of 90 °C, stirring speed of 260 rpm, and polishing time of 10 min. The system achieved a polished surface with 73% reduction in surface roughness. Compared with other electropolishing processes, the system decreased material mass loss rate following electropolishing of titanium alloys, making it suitable for surface polishing of additively or conventionally melt-cast fabricated titanium alloys. Using the deep-eutectic solvent for electropolishing of Ti6Al4V not only improves surface hydrophobicity, but also enhances electrochemical corrosion resistance. Furthermore, compared with electropolishing behaviour in green nonaqueous solvents, a similar electropolishing mechanism occurred in deep-eutectic solvents, but the electropolishing efficiency in the ZnCl2-urea deep-eutectic system was higher, and its surface mass loss become lower than that of the sodium chloride-glycol electropolishing systems. The developed system provided a new approach for surface finishing of titanium alloys and has great potential for engineering applications.

Electrochemical Polishing of Ti and Ti6Al4V Alloy in Non-Aqueous Solution of Sulfuric Acid

“…The price of choline chloride is eight times higher than that of H 2 SO 4 . Despite the need to use lower temperatures, due to the risk of overheating the methanol, using a H 2 SO 4 -based electrolyte is way cheaper than a DES; hence, more companies would be interested in this kind of solution [ 29 , 35 , 36 ].…”