REACTION OF TIO2-AL-C IN THE COMBUSTION SYNTHESIS OF TIC-AL2O3 COMPOSITE

Reaction mechanisms and the thermal structure in the reaction zone during the combustion of TiO2, Al, and C to form TIC-Al2O3 composite were studied. The reaction between each component was studied and the combustion wave structure and real-time temperature profile were analyzed. Titanium aluminide species, present in the aluminothermic reduction of TiO2, did not occur in the presence of C, because of the high thermodynamic stability of TiC. The activation energies of the exothermic reaction in the 3TiO(2)-4Al-3C system were determined by DSC analysis. This suggests that the combustion reaction is mainly controlled by carbon diffusion through solid TiC. The combustion wave was observed to propagate in an unstable mode. The temperature profiles in the reaction zone were of the sawtooth type and the products were of layered structure.