Sintering of nano structural WC with cobalt matrix synthesised from soluble raw materials

Nano sized tungsten carbide WC powder was synthesised using water soluble raw materials. Ammonium metatungstate AMT and glycine were applied as tungsten and carbon sources. They were dissolved in water and spray-dried before thermal synthesis in argon atmosphere. The particle size was in average 50 nm and grain size was in average 12-13 nm. The synthesized nano size tungsten carbide powder and commercial submicron and micron tungsten carbide powders were mixed with cobalt powder with a ratio of 80:20 by weight. The powders were consolidated by spark plasma sintering under vacuum at 1180ºC. The effect of powder properties and phase structure on sintering mechanism was investigated. Mechanical and microstructure evaluation of the sintered compacts were carried out by dynamic indentation, electron microscopy and X-ray diffraction. The influence of grain growth of the carbides on mechanical properties was evaluated. The decomposition of fine carbides was also investigated.