Electrodeposition and corrosion characterisation of micro- and nano-crystalline aluminium from AlCl3/1-ethyl-3-methylimidazolium chloride ionic liquid

This study reports on the electrodeposition of Al from AlCl3/1-ethyl-3-methylimidazolium chloride (EMIC) ionic liquid, with the aim at determination of the mechanism applied and correlation of deposition kinetics and coulombic current efficiency with the microstructure and corrosion behaviour of Al deposits. Cyclic voltammetry studies were conducted on both platinum and steel substrates with various scanning rates and reversal potentials. Potentiostatic electrodeposition experiments were applied to obtain functional Al layers on low carbon steel substrates and the effect of deposition potential on the deposit morphology and crystal size was investigated using SEM-EDX and XRD. Nano-crystalline Al deposits were obtained on low carbon steel substrates using polarisation potentials more negative to −600 mVvsAl, and the Al crystallite size was scaled down to 28 nm at −700 mVvsAl. Nano-crystalline deposits, with brighter and flatter surfaces, showed higher corrosion resistance in aqueous chloride solutions.