Capacitor Electrical Discharge Consolidation of Metallic Powders—A Review

Abstract

Manufacturing metallic materials from elemental or alloyed powders is an option in many industrial processes. Nevertheless, the traditional powder metallurgy processing including furnace sintering is at times detrimental for the microstructure attained in the powders. Alternative sintering processes based on the use of electricity and the energy obtained by the Joule effect in powder particles can be quick enough to avoid microstructural changes. In particular, when the energy is stored in a capacitor and then discharged, the heating process is extremely quick, lasting milliseconds or even microseconds. This process, generally known as electrical discharge consolidation, has been applied to a wide variety of metallic materials, easily preserving the original microstructure of the powders. Both porous or homogeneous and highly densified material can be obtained, and without losing the desired properties of the consolidated material. A general overview of the process and applications, as well as the results obtained by different research groups around the world, have been reviewed in this manuscript.

Ultrahigh Temperature Flash Sintering of Binder-Less Tungsten Carbide within 6 s

“…Initial attempts were performed by applying a straight 6 kA electric discharge using a single step for 6 s. By doing so, the pressed particles were ejected out of the die because of their low electrical conductivity. Presumably, such 6 kA discharge could not effectively flow across the powder (due to the presence of an oxide layer on the particles surface) [49] causing uneven heating. Under these conditions the voltage limit of 12 V was reached.…”

Effect of Holding Time on Densification, Microstructure and Selected Properties of Spark Plasma Sintered AA7075-B4C Composites

“…Additionally, a shorter holding time allows the preservation of a finer microstructure [ 25 ]. In this technique, a pulsed DC current (Joule heating) combined with a simultaneously applied compaction pressure, contributes to the fast densification of the powders [ 26 ]. While SPS involves a lower sintering temperature than conventional techniques, spark discharges can be generated in the gaps between the powder particles, which enhance the evaporation of oxides due to a locally high temperature increase on the surface of the powder particles, mainly at the heating stage.…”

“…While SPS involves a lower sintering temperature than conventional techniques, spark discharges can be generated in the gaps between the powder particles, which enhance the evaporation of oxides due to a locally high temperature increase on the surface of the powder particles, mainly at the heating stage. This facilitates the neck formation necessary for effective bonding between the aluminum particles [ 26 , 27 , 28 ].…”

Wear and Corrosion Resistance of AlSi10Mg–CP–Ti Metal–Metal Composite Materials Produced by Electro-Sinter-Forging

“…Among powder metallurgical techniques, Electro-sinter-forging (ESF) [16,17], a single pulse electro-discharge sintering (EDS) technique [18], was shown to be effective in producing a Ti-AlSi10Mg metal-metal composite [19]. By properly tuning the process parameters, densities up to theoretical ones are achievable without intermetallic phases.…”