Burning velocities in catalytically assisted self-propagating high-temperature combustion synthesis systems

The current work presents an experimental study of catalytically assisted s elf-propagating high-temperature synthesis (SHS) of the tantalum/carbon mat erial system. The effects of controlled amounts of two gas-phase transport agents (carbon dioxide and vaporized iodine) were examined. The gas-phase t ransport agents resulted in burning velocities 2 to 4 times faster than bur ning velocities observed in comparable catalytically assisted and unassiste d Ta/C SHS systems. The gas-phase transport agents clearly augment the comb ustion synthesis process. The burning velocities of the catalytically assis ted, non-melting SHS systems were found to be strong functions of particle size, pressure and the amount of gas-transport agent present. The results a re compared with previous studies of both catalytically assisted and unassi sted Ta/C SHS, and discussed in the context of proposed transport mechanism s. (C) 2001 by The Combustion Institute.