Electrodeposition of aluminum-vanadium alloys from the aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt

摘要

The electrodeposition of Al-V alloys was investigated in the VCl_2-saturated 66.7-33.3 mole percent aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt at 353 K. Because the reduction of V(II) occurs at potentials considerably negative of the Al(III)/Al electrode reaction, Al-V alloys cannot be electrodeposited from this melt without the use of the additive, 1-ethyl-3-methylimidazolium tetrafluoroborate. In the presence of this additive, the vanadium content of electrodeposited alloys increased with increasing cathodic current density or more negative applied potentials. X-ray analysis of Al-V alloys that were electrodeposited on a rotating copper wire substrate indicated that these alloys did not form or contain an intermetallic compound, but were nonequilibrium or metastable solid solutions. The chloride-pitting corrosion properties of these alloys were examined in N_2-saturated aqueous NaCl by using a potentiodynamic polarization technique. Alloys containing ～10 a/o vanadium exhibited a pitting potential that was +0.3 V positive of that for pure aluminum. However, this pitting potential was inferior to that measured for aged Al-V alloys that were prepared by sputter deposition.