Novel sustainable silicothermic synthesis of phase-pure TiB2 fine powder

Abstract Phase pure TiB2 powder of 100–400 nm was synthesized at 1100 °C via a novel sustainable silicothermic reduction technique using TiO2, Na2B4O7 and Si powders as starting materials. By introducing sodium salts as source of Na2O into the reactant mixture, the original water-insoluble byproduct SiO2, which is hard eliminated from resultant product in the conventional silicothermic reduction process, was transformed into water-soluble Na2Si2O5, making it much easy to remove it from the reacted mass via simple hot water washing. Consequently, a ‘‘post reduction’’ leaching process with a strong acid, generally required by the conventional metallothermic processes, was successfully avoided, and the relevant environmental concerns could be alleviated. Moreover, the aqua Na2Si2O5 could be readily recycled and used as a precursor for preparing many other types of valuable materials. Evaporation loss of silicon in the reduction process was dominated by SiO (g) resultant from the interactions between Si, SiO2 and Na2Si2O5 at test temperatures. By using 5 wt% excessive Si, TiO2 and Na2B4O7 were completely converted into TiB2 at 1100 °C.