Electrodeposition of Al-Cr-Ni Layer by Pulse Electrolysis in AlCl₃-EMIC Molten Salt

Abstract

To improve the oxidation resistance of TiAl intermetallic compounds under high temperature conditions, electrodeposition of an Al, Cr, and Ni layer was carried out by constant potential control or potential pulse control in AlCl₃-EMIC (1-ethyl-3-methyl-imidazolium chloride) ambient-temperature molten salt containing NiCl₂ and CrCl₂ at 338 K. The electrodeposition of Al, Cr, and Ni occurred at potentials lower than 0.0 V vs. A1/A1³⁺. Ni concentration in the deposit was about 9 at% at 0 V. However, it decreased with a decrease in potential to 1 at% at −0.2 V. The potential pulse technique enhanced the Ni concentration in the deposit to 20-27 at%. Cr concentration was also enhanced by pulse potential control: the concentration of Cr was raised to 15 at%. In all electrodeposits, sharp peaks corresponding to Al metal were detected with a relatively high background by XRD analysis. It is conceivable that deposit layers consisting of Al, Cr, and Ni may be amorphous.