On the titanium carbide TiC synthesis from oxycarbide Ti2OC

Titanium carbide synthesis from oxycarbide Ti2OC following equation: Ti2OC + 2 C --> 2 TiC + CO is the ultimate step in the industrial process of carbothermic reduction of titanium dioxide. There is not really one solid/solid reaction but two simultaneous solid/gaz reactions Ti2OC + CO --> 2 TiC + O-2 2 C + O-2 double left right arrow 2 CO with an apparent activation energy of 492 +/- 12 kJ.mol(-1). The reaction mechanism is governed by a diffusionnal process whose limiting step is probably the centripetal diffusion of carbon inside the oxycarbide grains. Their composition slowly slides towards that of carbide during the reaction, but no morphological change is observed, except the growth of the cubic lattice parameter from that of the oxycarbide (0.4295 nm) to that of the carbide (about 0.432 nm) which remains always slightly sub-stoechiometric.