DYNAMIC MODELING OF MATERIAL AND PROCESS PARAMETER EFFECTS ON SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS OF TITANIUM CARBIDE CERAMICS

A dynamic, finite-difference model evaluation of titanium carbide (TiC) ceramic processing by self-propagation high-temperature synthesis (SHS) has revealed that material and process parameters have a significant influence on SHS reaction propagation kinetics. Examination of the effects of Ti:C stoichiometry variations and the presence of pre-reacted TiC diluents in the initial (Ti + C) reactant powder mix indicates that off-stoichiometric ratios and dilution additions tend to lower SHS reaction velocities. Increasing compact preheat temperatures, lowering powder particle sizes and raising compact packing densities, on the other hand, cause a significant increase in this reaction variable. Model results are supported by experimental studies on dilution, stoichiometry and preheat temperature effects on SHS velocity, and other literature data on packing density and particle size effects on this parameter. Simulations also suggest that effects of these initial conditions are due to their influence on adiabatic reaction temperatures and heat transfer patterns produced during the process. Critical selection of initial material and process conditions thus appears to be of vital importance during SHS processing of TiC ceramics.