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The densification behavior of zirconium nitride powder is investigated for various temperature and pressure conditions imposed by spark plasma sintering and high voltage electric discharge consolidation techniques. The crystal structure, chemical composition, porosity, and grain size of the powders and processed specimens are analyzed by X-ray diffraction, scanning electron microscopy, and energydispersive X-ray spectroscopy. The outcomes of the two considered consolidation techniques are comparatively assessed. Vickers micro-hardness of the processed ZrN specimens is investigated, and hardness dependence on porosity is analyzed. The densification mechanism of ZrN consolidated by spark plasma sintering is revealed by applying the constitutive equation of the continuum theory of sintering, and it turns out to be a similar mechanism to hot pressing. Application of the sintering constitutive equations shows that the mechanism of ZrN densification by high voltage electric discharge consolidation method depends on the magnitude of the applied voltage.

This paper reviews research articles published in the former USSR and post-soviet countries on the consolidation of powder materials using electric current that passes through the powder sample and/or a conductive die-punch set-up. Having been published in Russian, many of the reviewed papers are not included in the mainstream electronic databases of the scientific articles and thus are not known to the scientific community. The present review is aimed at filling this information gap. In the paper, the electric current-assisted sintering techniques based on high- and low-voltage approaches are presented. The main results of the theoretical modeling of the processes of electromagnetic field-assisted consolidation of powder materials are discussed. Sintering experiments and related equipment are described and the major experimental results are analyzed. Sintering conditions required to achieve the desired properties of the sintered materials are provided for selected material systems. Tooling materials used in the electric current-assisted consolidation set-ups are also described.