KINETICS AND PHASE EVOLUTION DURING CARBOTHERMAL SYNTHESIS OF TITANIUM CARBIDE FROM CARBON-COATED TITANIA POWDER

Kinetics and phase evolution of the TiC formation process by carbother mal reduction of carbon-coated titania (TiO2) powder were investigated using TGA, XRD, and chemical analysis. The TiC synthesis in the prese nt work proceeded via forming titanium oxycarbide (TiCxOy) followed by its purification toward titanium carbide (TiC). The formation of TiCx Oy was achieved via two routes. The uniformly coated pyrolytic carbon on fine titania particles formed the first TiCxOy phase at temperature of 1000 degrees C. The additional TiCxOy formed from Ti3O5 as tempera ture increased. The activation energy of the additional TiCxOy formati on process was calculated to be 278.1 kJ/mole. The resultant TiC powde rs prepared at 1550 degrees C for 4 h in flowing argon showed fine par ticle size (0.1-0.3 mu m), oxygen content of 0.57 wt%, lattice paramet er of 4.331 Angstrom, uniform particle shape, and loose agglomeration between particles. (C) 1997 Elsevier Science Limited.