Abstract
The electrochemical oxidation of Ti3+ ions in LiCl-KCl eutectic melt at 470°C occurs in two different ways according to the current densities. In our experimental conditions (concentration of Ti3+ ions 0.11 mol kg−1) for potentials lower than −0.48 V (vs chlorine electrode) and current densities lower than 10 mA cm−2 soluble Ti4+ ions are formed, whereas, for higher potentials solid K2 TiCl6 precipitates at the electrode resulting in a partial passivation of the electrode. Both reactions have been studied by means of impedance measurements which have shown the reversibility of the electrochemical reaction (k 0=0.25 cm s−1; α=0.3) and the porosity of the K2 TiCl6 layer electrochemically formed. The thickness of this layer has been estimated from the amount of electricity involved in the reaction and from the resistance and the capacitance characterising the deposit, measured at high frequencies. This comparison shows that the deposit is composed of a very thin (∼0.1 μm) barrier layer covered by a very thick (∼70 μm) porous external layer.
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D. Ferry, E. Noyon and G. Picard,J. Less common Metals 97 (1984) 331.
D. M. Ferry, G. S. Picard and B. L. Tremillon,J. Electrochem. Soc. 135 (1988) 1443.
D. M. Ferry, G. S. Picard and B. Tremillon,Trans. Instn Min. Metall. Sect. C 97 (1988) C21.
J. H. Mui and S. N. Flengas,Can. J. Chem. 10 (1962) 997.
F. Seon, G. Picard and B. Tremillon,Electrochim. Acta 28 (1983) 209.
A. J. Bard and L. R. Faulkner, in ‘Electrochemical Methods, Fundamentals and Applications’, John Wiley, New York (1980).
E. Warburg,Wied. Ann 67 (1899) 493;Drud. Ann 6 (1901) 125.
E. Chassaing, F. Basile and G. Lorthioir, in ‘Titanium '80, Science and Technology’, Proceedings of the 4th International Conference on Titanium, Kyoto, Japan, May, 19–22 (edited by H. Kimura and O. Izumi) (1980).
R. de Levie,Electrochim. Acta 9 (1964) 1231.
CRC Handbook of Chemistry and Physics, 69th edition, CRC Press (1988–89).
J. Vereecken, H. Terryn, B. van der Linden, ‘Comptes Rendus du 3ème Forum sur les Impédances Electrochimiques’, Montrouge, France (1988).
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Ferry, D.M., Picard, G.S. Impedance spectroscopy of the Ti(IV)/Ti(III) redox couple in the molten LiCl-KCl eutectic melt at 470°C. J Appl Electrochem 20, 125–131 (1990). https://doi.org/10.1007/BF01012481
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DOI: https://doi.org/10.1007/BF01012481