Electrochemical preparation of aluminium-nickel alloys by Under-Potential Deposition in molten fluorides

Mathieu Gibilaro (1) , Laurent Massot (1) , Pierre Chamelot (1) , Pierre Taxil (1)

1 LGC - Laboratoire de Génie Chimique

The electrochemical behaviour of AlF3 was investigated in LiF-CaF2 medium first with inert tungsten and then with reactive nickel electrodes. Cyclic voltammetry, square wave voltammetry and chronopotentiometry indicated that the reduction of Al(III) in Al(0) is a single-step process exchanging 3 electrons: Al(III) + 3e- = Al. The electrochemical reduction is controlled by the diffusion of AlF3 in the solution. On a nickel electrode, a depolarisation effect for Al(III) reduction was observed in cyclic voltammetry due to the formation of Al-Ni alloys when aluminium ions react with the nickel substrate. Galvanostatic and potentiostatic electrolyses on a nickel electrode led to the formation of four nickel aluminides characterised by SEM: AlNi3, AlNi, Al3Ni2 and Al3Ni. Layers with a uniform composition of AlNi3, AlNi and Al3Ni2 were prepared by varying the electrolysis potential, the current density and duration of intermetallic diffusion.

Mots clés: Molten Fuorides; Aluminium; Reactive Electrode; Aluminides; Under Potential Deposition.

Domaines: Génie des procédés; Génie chimique

Mathieu Gibilaro, Laurent Massot, Pierre Chamelot, Pierre Taxil. Electrochemical preparation of aluminium-nickel alloys by Under-Potential Deposition in molten fluorides. Journal of Alloys and Compounds, 2009, 471 (1-2), pp.412-420. ⟨10.1016/j.jallcom.2008.03.115⟩. ⟨hal-03572977⟩