Electropolishing of Al and Al alloys in AlCl 3 /trimethylamine hydrochloride ionic liquid

We have investigated the electropolishing (EP) of aluminum (Al) and its alloys in an ionic liquid composed of anhydrous aluminum chloride and trimethylamine hydrochloride. The EP mechanism of Al was investigated by linear sweep voltammetry. The optimum conditions for EP of Al and Al alloys including the ionic liquid components, current density and polishing time were systematically explored. Moreover, the microstructure and chemical compositions of Al before and after EP were measured by SEM, AFM, XPS and XRD, respectively. Compared to EP in strong acid solution, EP of Al in this ionic liquid can achieve the equivalent polishing effect with less mass loss. Importantly, the polishing ability of this ionic liquid remains stable even after EP for 50cycles. The corrosion resistance of electropolished Al is drastically enhanced due to the formation of the compact passive layer on the mirror-like bright surface.