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 °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 silicide 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%.