Preparation of TiC powders and coatings by electrodeoxidation of solid TiO 2 in molten salts

Abstract

Porous TiC nanoparticles have been synthesised from sintered pellets comprising a powder mixture of TiO₂ and graphite by electrodeoxidation in molten CaCl₂–NaCl eutectic. Electrolysis was conducted at 850°C in argon at an applied constant voltage of 3·1 V. The formation of TiC from the oxides/C mixture occurred at less cathodic potentials than those for electrodeoxidation of TiO₂ to titanium metal. No titanium metal was observed during electrolysis, as confirmed by XRD. These findings were consistent with the thermodynamic predictions. It was found that CaTiO₃ was formed during electrolysis and all the titanium oxides disappeared after 4 h electrolysis in a eutectic CaCl₂–NaCl melt at 850°C, leaving CaTiO₃/C/TiC mixtures behind at the cathode. It was also found that the formed CaTiO₃ was electrodeoxidised to form TiC by prolonged electrolysis. The present results further demonstrated that an adhesive layer of Ti_0·55C_0·45 was formed on graphite substrates by electrodeoxidation of TiO₂ on the substrates.