Effects of C particle size on the ignition and combustion characteristics of the SHS reaction in the 20 wt.% Ni-Ti-C system

C particle size plays an important role in the ignition and combustion characteristics of the SHS reaction in the 20 wt.% Ni-Ti-C system. When coarse C particles (similar to 38 and similar to 75 mu m) are used, the SHS reactions consist of two different combustion stages with different brightness intensity of the combustion wave; XRD results indicate that the first and second combustion stages mainly correspond to the formation of Ni-Ti compounds and TiC ceramics, respectively. However, the final reaction is incomplete with a few Ni-Ti compounds and unreacted C. In contrast, when the fine C particle (similar to 1 mu m) is used, the SHS reaction consists of only one combustion stage with high brightness intensity of the combustion wave; XRD result indicates that final products consist of TiC and Ni, without any intermediate phase. With the decrease of C particle size, the wave velocities increase, and the ignition time becomes shorter. In addition, the morphology of TiC particulate changes to near-spherical, as C particle size decreases.