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

The influence of the pulsed DC current and the electric field oil 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. (C) 2008 The Ceramic society of Japan. All rights reserved.