Mechanochemical synthesis of tungsten carbide powders induced by magnesiothermic reduction of WCl6 and Na2CO3 raw materials


Aytekin N. O. , Ağaoğulları D. , Öveçoğlu M. L.

MATERIALS RESEARCH EXPRESS, cilt.6, 2019 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 6 Konu: 9
  • Basım Tarihi: 2019
  • Doi Numarası: 10.1088/2053-1591/ab2c34
  • Dergi Adı: MATERIALS RESEARCH EXPRESS

Özet

The present study explains the synthesis of tungsten carbide (WC and W2C) powders from WCl6 and Na2CO3 containing blends via magnesiothermic reduction induced by mechanochemical reactions. Mechanochemical synthesis (MCS) was conducted at room temperature in a high-energy ball mill (SPEX (TM) 8000D Mixer/Mill) utilizing tungsten carbide vial/balls. A subsequent purification treatment using HCl and distilled water was applied on the mechanochemically synthesized (MCS'd) powders in order to leach out unwanted NaCl and MgO by-products. The optimum production conditions of tungsten carbide powders were examined in regard of MCS time and weight amounts of Na2CO3 and Mg reactants. Phase, microstructural and thermal characterizations of the MCS'd and leached powders were performed using x-ray diffractometer (XRD), stereo microscope (SM), scanning electron microscope/energy dispersive spectrometer (SEM/EDS), particle size analyzer (PSA), differential scanning calorimeter (DSC) and transmission electron microscope (TEM). Stoichiometric or 50 wt% excess Mg added WCl6 -Na2CO3-Mg mixtures resulted in the formation of both WC and W2C powders with an amount of WCl6, WO2Cl2 and W phases after MCS and leaching processes. However, WCl6 and WO2Cl2 were disappeared, and only W-2 C, WC and W phases were achieved from the 50 wt% excess Na2CO3 added WCl6-Na2CO3-Mg mixtures. The best results were obtained for the WCl6-Na-2 CO3-Mg mixtures with 70 wt% excess Na2CO3 which pure WC powders owning an 191 nm average particle size yielded after MCS for 5 h and leaching with 7 MHCl.