Synthesis of WC-8Co cermet powder in WO3-Co3O4-C system by in situ carbothermic solid reduction method under hydrogen atmosphere: (phase, microstructural and thermodynamic analysis)

WC-Co cermets are among the advanced engineering materials that are considered for their special properties such as abrasion resistance and high hardness. The aim of this study was to determine the optimal amount of carbon in raw materials and industrial production of WC-8Co cermet powder from metal oxides WO3, Co3O4 and activated carbon by solid carbothermic reduction method in situ and under a hydrogen gas atmosphere. The main challenge in this case is the incomplete formation of tungsten carbide and the fact that tungsten remains free in the mixture of materials, which is related to the lack of carbon in the composition of raw materials and the need to add more carbon compared to its stoichiometric amount. Therefore, it is necessary to change the amount of carbon experimentally. For this purpose, the raw materials were homogenized in 5 different ratios with different amounts of activated carbon as the main variable in a mixer for 3 hours. The powder samples were then subjected to carbothermic reduction at 1200oC for 3 h at a heating rate of 10 oC.min⁻¹ and subjected to a hydrogen atmosphere at a pressure of 1 atmosphere. According to the results of phase studies and X-ray dispersion spectroscopy and microstructural studies of the sample electron microscope with the combination (10.108gr WO3, 10.90gr Co3O4 and 58.62gr C) show the best conditions in terms of the obtained phases. The hydrogen atmosphere applied in the furnace acts both as a facilitator of the reduction process and as a protective layer against re-oxidation of the products. In this case, the majority phase is tungsten carbide, which is placed next to small amounts of cobalt as the adhesive phase. So that the results of scanning electron microscope image also confirm this and the average number of composite particles in this case is about 100 microns.