Synthesis of nano-WC from water soluble raw materials: Effects of tungsten source and synthesis atmosphere on chemical and phase structure evolution

The chemical synthesis of WC from water-soluble precursors was studied. Ammonium paratungstate APT, ammonium metatungstate AMT as tungsten source and glycine as a carbon source were dissolved in water and spray-dried, and thermal synthesis in Ar and Ar-4 vol-% 4H2 atmospheres was performed. In order to understand the effects of the tungsten source and atmosphere on the synthesis steps, and chemical and phase structure, thermogravimetry (TGA) with Differential Scanning Calorimetry (DSC) and mass spectrometry was used togetherwith X-ray diffractometry and chemical analysis. The eventual goal is to produce pureWC phasewithout lower carbides and on the other hand without extra unreacted carbon. Due to the better solubility and subsequently more homogeneous nucleation of WC, AMT was found to be a more suitable precursor. Using AMT and glycine, 10-100 nmsizedWCwas synthesised at 1300 °C in both atmospheres. However, extra carbon was present in the product. New insights were gained into the reaction sequences.