Discrete Finite-Element Simulation of Thermoelectric Phenomena in Spark Plasma Sintering

Realistic microstructures of compacted powders formed by spark plasma sintering or field-activated sintering technology were modeled using the discrete finite-element method. Two key thermoelectric characteristics were studied: (1) the effect of the electric current pattern, i.e., direct current (DC) and pulsed current, on temperature distributions in the compacted powders, and (2) the effect of compaction modes, i.e., isostatic compaction and uniaxial compaction, on conductivity. Simulations showed that, for the same electric power input, pulsed current offered faster heating and more uniform temperature distribution in the compact than did DC. Additionally, using uniaxial compaction, the effective conductivity of the compact in the compaction direction was higher than in the transverse direction, by as much as 20%. Experimental measurements confirmed the existence of anisotropy of conductivity in the compact.