On Joule heating during spark plasma sintering of metal powders

Joule heating as a primary heating source mechanism was probed during spark plasma sintering (SPS) of pure metal powders (Fe, Ni and Cu). Resistance to electric path was estimated from voltage–current measurements obtained online during these experiments. Resistance was observed to saturate at the same value irrespective of the type of metal powder, after attaining a sintering temperature of ∼0.3Tm. This saturation in resistance is attributed primarily to the Joule heating that occurs at the graphite-foil and punch in an SPS system.