INFLUENCE OF REACTANT CHARACTERISTICS ON THE MICROSTRUCTURES OF COMBUSTION-SYNTHESIZED TITANIUM CARBIDE

The influence of reactant characteristics on morphological -development through the stages of combustion synthesis was investigated using a titanium-carbon system. The effect of the characteristics of a variety of carbons (carbon blacks, graphites, and cokes) and a variety of titanium powders on the density and microstructure of combusted and uncombusted sample compacts was studied. The size of the titanium particles had a relatively small influence on the density of the final (TiC) product but had a significant effect on its microstructure. The structure of the carbon blacks (as judged by the n-dibutyl phthalate absorption number, DBP) had a direct influence on the density of the uncombusted and combusted samples: low-structure carbon blacks resulted in higher densities for both cases. Products made with natural graphites had higher densities than those made with synthetic graphites. The surface area of carbon and graphite reactant powders had less influence on the density of the product than on its network morphology. Cored structures in TiC products made from certain carbon and graphite powders were observed and are explained in terms of their ash (oxide) content.