Self-propagating high-temperature synthesis of TiCxNy-TiB2 ceramics from a Ti-B4C-BN system

An experimental study on direct formation of TiCxNy-TiB2 ceramics by self-propagating high-temperature synthesis (SHS) was conducted using a Ti-B4C-BN system. The effects of the C/(C + N) ratio on the combustion behavior and reaction products were investigated. Experimental characterizations of quenched samples show that the combustion reaction started with the formation of highly substoichiometric TiNy and TiB due to the solid-state reaction between Ti and BN; and then the TiNy precursor and TiB dissolved back into the titanium melt, forming the Ti-B-N liquid, which in turn transformed to the Ti-B-N-C liquid due to the dissolution of the carbon atoms diffused away from B4C. Finally, the TiCxNy and TiB2 particles are formed from the melt through the dissolution-precipitation mechanism.