A direct electrochemical route from oxides to Ti-Si intermetallics

The titanium silicide intermetallics have been directly prepared from the mixture of titanium oxide (TiO2) and silicon oxide (SiO2) powder by using the solid-oxygen-ion-conducting membrane (SOM) electrolysis process. The electrochemical process was carried out in a molten flux CaCl2 at 950 degrees C with a potential of 3.5-4.0 V. The effects of the stoichiometry of the initial mixture on the electrolysis characteristics and the final product compositions were investigated. It has been found that the molar ratio of TiO2:SiO2 dominates the composition of final products. A single-phase suicide Ti5Si3 intermetallic was obtained when the TiO2:SiO2 molar ratio is 5:3; the TiSi was identified as the dominant phase with a minor amount of TiSi2 at TiO2:SiO2 molar ratio 1:1; three silicide phases, Ti5Si4, Ti5Si3 and TiSi, were found coexisting in the final product produced from TiO2-SiO2 mixture of molar ratio 5:4; the product of electrolysis consisted of the compound Ti5Si3 and the pure metal Ti as TiO2:SiO2 molar ratio equals to 3:1; and two silicide phases, TiSi and TiSi2, are formed as TiO2:SiO2 molar ratio equals to 1:2. The preliminary experimental results suggest that the electro-deoxidization process is fast and the current efficiency reached 75%. (C) 2010 Elsevier Ltd. All rights reserved.