TiC-xNi CERMETS MADE BY SHS/QP METHOD—Ⅰ. STUDY ON THE COMBUSTION PROCESS

SHS/QP technique as a new method is aneasy and economical way, which combines SHS and dynamic consolidation to fabricate full density composites in a single processing operation. So, a thorough underst anding of the SHS process and the optimization of the pressing pattern are of the same importance. With the increase of metal contents in TiC-xNi, both the adiabatic and measured combustion temperatures decrease. Because of the heat loss and the industrial raw powders used in the experiment, the measured combustion temperatures are lower than the adiabatic temperatures. Maximum value on the propagating curve is observed at the Ni content about 20mol%, owing to the melting of Ni. Expansion of the sample after SHS is observed. Both combustion temperatures and propagating rates decrease with the add of diluent. By Novozhihov equation, the calculated activation energy for SHS of TiC-20mol% Niis 166kJ/mol, close to that of the Ti and Creaction in the high temperatureregion, which indicates a solution and precipitation controlled mechanism. By CFQ method, the structure formation mechanism of SHS TiC-20mol% Ni was proposed.