Composition and structure of Al–Sn alloys formed by constant potential electrolysis in an AlCl3–NaCl–KCl–SnCl2 molten salt

To form Al–Sn alloys for bearing materials, molten salt electrolysis was performed in an AlCl3–NaCl–KCl molten salt containing SnCl2 at 423 K. The voltammogram showed that the cathodic reduction of the Sn ions started at a potential of 0.5 V vs. Al/Al(III) in the molten salt showing that deposition of pure Sn was possible at 0.5 V. Co-deposition of Al and Sn occurred at potentials more negative than 0.1 V. The co-deposit was composed a solid solution of Al and Sn. The ratio of the Sn in the electrodeposits decreased with the potential from 100 at.% at 0.2 V to 19 at.% at −0.3 V. In the structural observations, electrodeposits with an alternate stacked structure of Al and Sn is obtained at −0.075 V.

► Al–Sn alloys were electrodeposited in AlCl3–NaCl–KCl molten salt containing SnCl4.
► Composition of Al–Sn alloys changed by electrolysis potential.
► The stripe structure deposits of Al and Sn was formed at 75 mV vs. Al/Al(III).