Aluminium electrodeposition fron ionic liquid: effect of deposition temperature and sonication

Since their discovery, ionic liquids (IL) have attracted a wide interest for their potential use as medium for many chemical processes, which vary from extraction, to catalysis, to organic synthesis. Their use as electrochemical media allowed the electrodeposition of metal that are impossible to reduce in aqueous media.
In particular, the first generation ILs (the so called chloroaluminated ILs) have made possible the deposition of Aluminium from his chloride salt. Despite the discovery of this process in the nineties, nowadays aluminium electrodeposition from chloroaluminate ILs still maintains a number of open issues regarding both fundamental and  technological aspects.
The present communication aims to shed some light about the aluminium electrodeposition process as concerns the effect of deposition parameters. Thick Al-coatings (20 μm) were electrodeposited on brass substrate at different temperature, potential and stirring conditions. The so obtained coatings were investigated by means of optical and electronic microscope (Figure 1), rugosimetry and X-ray diffraction to asses their morphology and phase composition. Finally, with the intent to correlate the coating structures with their corrosion properties, electrochemical corrosion tests (Open Circuit Potential, Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy) were performed.