Preparation of titanium diboride from the borothermic reduction of TiO2, TiOx(OH)y, or Ti(O-n-Bu)4-derived polymers

Abstract

The reaction between amorphous boron powder and TiO2, TiOx(OH)y or titanium-alkoxide derived polymers (B : Ti = 4 : 1) was studied at 25–1500°C in a flow of argon. The borothermic reduction of TiO2 resulted in formation of Ti2O3 and TiBO3 at 600°C; TiB2 was formed by further borothermic reduction of Ti2O3 and TiBO3 above 700°C; the overall reaction was found to be complete at 1300°C. The particle sizes of TiB2 powders obtained were directly related to the starting material used as the titania source. The largest particles were obtained when TiO2 powder was used as the starting material The particles were smaller when TiOx(OH)y powder was used, and the smallest particles were obtained when the partially-hydrolyzed Ti polymer, [BuOTiO1·5]n, was used as the titanium source. The pyrolysis chemistry of these precursors as well as the morphology of the pyrolysis products were studied by FT-IR, TGA, SEM, XRD, BET, elemental analyses and particle size analyses.