Electrochemical Reduction of Zirconium Oxide and Co-Deposition of Al-Zr Alloy from Cryolite Molten Salt

The electrochemical reduction of zirconium oxide in a molten salt of 2.4NaF·AlF3 (molar ratio = 2.4) was studied at 1273 K. Cyclic voltammetry results show that Zr(IV) ions are first reduced to an intermediate valence and, then, are co-deposited with aluminum to form an Al-Zr alloy. Potentiostatic electrolysis experiments were carried out at different potentials (−0.95 and −1.25 V) and at 1273 K, and the electrolysis products were characterized using SEM-EDS and XRD. The XRD analysis confirms that a mixture of cryolite molten salt and ZrO2 was electrodeposited at −0.95 V, while aluminum and Al3Zr were electrodeposited at −1.25 V. The SEM analysis shows that the aluminum and Al3Zr were in two different phases.