Critical assessment 8: Outstanding issues in electropulsing processing

Abstract

The processing of materials using electrical pulses utilises effects other than resistive heating to stimulate changes in their microstructure and hence the properties. The direct effect of electropulsing has not, however, been fully understood. There remain issues that delay the industrialisation of the method and there are gaps in the scientific understanding of mechanisms. The thermodynamic description of electropulsing is based on a few oversimplified geometric models. The corresponding kinetic description remains qualitative and less than helpful in stimulating applications. The role of electropulsing in multiphase materials where the magnetic permeabilities of the phases are different has not been explored. Experiments on electropulse induced powder sintering reveal effects that are not related to resistive heating, but their origin has yet to be identified. Similar uncertainties apply to the mechanisms for electrically induced crystal rotation and texture evolution. Electropulse induced particle reconfiguration in liquid suspensions is a new field that is promising in helping to clean melts from insulating oxides. These, and other aspects connected with applications and scaling are critically assessed.