Influence of the current flow on the SPS sintering of a Ni powder

A nickel powder with the particle size 4.3 μm has been sintered, using a SPS apparatus, by identical set temperature, heating rate, dwell time and pressure in different moulds: (a) with graphite die and punches, (b) with alumina die and graphite punches and (c) with graphite die and punches including alumina spacers between punches and powder. Although all set sintering parameters are identical, the microstructure of the resulted nickel specimens depends on the moulds. The bulk density is higher when an alumina die is used. On the contrary, the bulk microstructure does not seem to be influenced by the graphite foil presence, generally used between the system parts. The present paper is an attempt to correlate the bulk microstructure evolution with the electric and thermal characteristics of the moulds and graphite foil, and the resulted current flow.

Research highlights▶ Spark Plasma Sintering is a novel processing very attractive, which generates lots of research, either to understand involved mechanisms or to synthesize new materials. The present paper is an attempt to correlate the bulk microstructure evolution with the electric and thermal characteristics of the moulds and the resulted current flow in Spark Plasma Sintering.