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Advances in Molten Salts

ISSN:
1-56700-142-4 (Print)

Chemical and electrochemical behaviour of titanium oxide and complexes in cryolite-alumina melts

S.V. Devyatkin
Institute of General and Inorganic Chemistry NANU, Palladin pr. 32/34, Kiev, Ukraine

J-C. Poignet
Laboratoire d'Electrochimie et de Physico-chimie des Materiaux et des Interfaces, ENSEEG, Domaine Universitaire, B.P.75, 38402 St. Martin d'Heres, France

J. Bouteillon
LEPMI, ENSEEG, Domaine Universitaire, BP 75, Saint Martin d'Heres, France

Abstract

In the present paper the possibility of in-situ production of aluminium-titanium alloys in aluminium electrolysis cells is discussed. Thermodynamic calculations showed, that TiO2 is reduced to lower titanium oxides both by carbon anode and aluminium cathode, leading to the passivation of both the electrode surfaces. CaTiO3 was found to be the best form to introduce TiO2 into the melt, preventing passivation of electrodes. Linear voltammetry experiments proved, that in cryolite-alumina melt with TiO2 addition the process is taking place in 2 steps: Ti(IV)+e → Ti(III) + 3e → Ti(0), while with addition of MgTi03 or CaTi03 deposition of Ti takes place in one irreversible step: Ti(IV) + 4e → Ti(0). Finally CaTiO3 dissolved in the cryolite-alumina melts is suggested to be the best candidate to produce aluminium-titanium alloys from the aluminium electrolysis cells.