Influence of pulsed DC current and electric field on growth of carbide ceramics during spark plasma sintering

Abstract

The influence of the pulsed DC current and the electric field on the growth of TiC and ZrC layers using Spark Plasma Sintering was investigated at temperature ranging from 1373 to 1823 K. From the results of XRD and EDS analyses, the product layer formed between Ti and C was only TiC, and the layer between Zr and C was only ZrC. In all systems, the thickness and the growth rate constant of the product layers were enhanced in the system with the current compared to that in the system with the negligible current. The activation energy for the TiC layer growth was calculated to be 269 ± 3 kJ/mol in the system with the current, which is smaller than the activation energy of 273 ± 2 kJ/mol in the system with the negligible current. In the Zr-C system, these values were 205 ± 7 kJ/mol and 224 ± 1 kJ/mol, respectively. The increase in the growth of the TiC and ZrC layers was unaffected by the current direction and suggested that the increased point defect mobility by passing the current was a dominant cause of the enhanced growth.

Pulse Electric Current–Aided Reactive Sintering of High‐Purity Zr3Al3C5

“…As most of the intermediate phases (except Al 4 C 3 ), such as Zr–Al intermetallics, ZrC, Zr 2 Al 3 C 4 , as well as the targeted Zr 3 Al 3 C 5 phase are electrically conductive, the pulsed current passes through the sintered compact and clearly enhances the reaction kinetics. In addition, it has also been reported that the application of an external field leads to the elimination of surface oxides by electrical discharge and thus favor the activation of the surfaces of particles, which may also result in more vigorous reactions …”

“…The rapid heating rates and short dwelling times applied have been shown to inhibit grain growth which in turn accelerates densification. Bulk samples with improved properties can be realized as well . Furthermore, it is generally accepted that the electric current pulses applied during the process result in surface purification and activation of the particles.…”

Electric Current Activation of Sintering: A Review of the Pulsed Electric Current Sintering Process

“…The effect of current on reactivity in the PECS has been investigated 56,87–89 . The reaction between Mo foils and Si wafers was investigated under PECS conditions with and without a current passing through the multilayer ensemble 56 .…”

A methodology to investigate the intrinsic effect of the pulsed electric current during the spark plasma sintering of electrically conductive powders

“…The analysis of the few previously reported experimental results on this matter is not conclusive. In fact, an intrinsic effect of the application of a pulsed electric current have been experimentally observed only on the solid-state diffusion during steel plates boriding [21] and on reactivity during diffusion couples experiments [22][23][24]. On the other hand, by imposing the same temperature and mechanical pressure, similar densities and microstructures were observed in electrically conductive ceramic samples heated by either restricting the current to flow only through the powder or with current allowed to pass through both the graphite die and the powder [20].…”