Kinetic approach to the carbothermic reduction of titanium dioxide

Kinetics of the titanium carbide synthesis by titania carbothermic reduction between 1470 and 1670 K, points out successively three reactions: (i) the fast reduction of the dioxide into the suboxide Ti3O5 up to a progress coefficient α = 0.17; (ii) the oxycarbide Ti2OC formation with c.f.c. structure (a 4.295 angstroms) for progress coefficient α like 0.17-1, involving the following steps: 2 Ti3O5↔6 TiO+2 O2, 6 TiO+3 CO↔3 Ti2OC+3 O2, 5 O2+5 C&rarr5 CO2, and 5 CO2+5 C↔10 CO; (iii) the carbide formation resulting from the substitution of oxygen by carbon, according to a slow diffusional process within the oxycarbide grains.