Fundamental investigations on the spark plasma sintering/synthesis process III. Current effect on reactivity

The solid-state reactivity between layers of Si and Mo was investigated under spark plasma sintering (SPS) conditions. The primary product phase was MoSi2 with Mo5Si3 as a minor phase. The thickness of the primary phase showed no dependence on the direction of the current in the SPS. However, the growth rate of the product phase showed a strong dependence on the current. The activation energy for the formation of the product under the influence of the current was calculated to be 468 kJ mol-1, which was in general agreement with reported values for growth in the absence of a current, suggesting the absence of mechanism change due to the influence of the current. The results are interpreted in terms of mass transport enhanced reaction due to the current. Investigations of the temperature, power, and displacement parameters in the SPS were made for cases of simultaneous synthesis and sintering of B4C and MoSi2.