Advanced Powder Technology, Vol.29, No.10, 2447-2455, 2018
Synthesis of metastable cubic tungsten carbides by electrical explosion of tungsten wire in liquid paraffin
This paper describes experiments addressing the synthesis of WC1 x (metastable cubic tungsten carbide). The experiments involved exploding tungsten wires of different diameters by passing high-current electric pulses through them. This was done while the wire was immersed in a liquid-paraffin media. The explosion was studied using a high-speed video camera and by analysis of the voltage and current signals. The different stages of the wire explosion were explained based on an analysis of the recorded signals and simple thermodynamic considerations. In most of the experiments, the wire was sublimated, and the formation of carbide particles occurred due to a chemical reaction between the explosion products and the paraffin, as well as the rapid condensation of the vapors. The synthesized powders were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA). It was found that, regardless of the experimental conditions, the WC1 x phase contained approximately 42.5 at.% carbon. If the energy injected into the wire was not sufficient to completely evaporate the tungsten, large particles consisting of WC, W2C, and W phases were formed via the liquid-state diffusion mechanism. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.