Role of mechanical activation in SHS synthesis of TiC

The effect of the mechanical activation of the reactants on the self-propagating high-temperature synthesis (SHS) of titanium carbide was investigated. The SHS experiments were performed on two compositions, Ti50C50 and Ti70C30, which define the homogeneity range of the TiC equilibrium carbide. Milling times were progressively increased up to the time at which a combustion-like process ignites spontaneously under milling. The combustion peak temperature, wave velocity, and ignition temperature were markedly influenced by the degree of mechanical activation of the reactants. In particular the ignition temperature was observed to decrease from a temperature corresponding to the melting point of Ti to 500degreesC. The apparent activation energy for propagation of the combustion wave was also determined (similar to100 kJ . mol(-1)) and was found to be independent of both the degree of mechanical activation and the composition of the starting mixture. (C) 2004 Kluwer Academic Publishers.