Analysis on Calcination Process of WC-Co Precursor Powder

In this paper, calcination of WC-Co precursor powders with different Co contents prepared by solution technique was investigated. Thermal analysis was carried out. The precursor powders after calcination process were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A mechanism of calcination of the precursor powder was proposed and substantiated by the experimental data. The mechanism was that carbon in Sample C (WC-3 wt.% Co) after calcination was provided only by the pyrolysis of soluble starch, while carbon in Sample A (WC-12 wt.% Co) was provided not only by the pyrolysis of soluble starch but also by the pyrolysis of methyl in acetate cobalt. The main phase after calcination was the mixture of WO3, CoO, and C. Moreover, ultrafine WC-Co composite powder was obtained after fast reduction-carbonization treatment. The morphology of WC-Co powder is hollow spherical granular structure where individual particles are cemented in the form of agglomerated ball and the mean particle size is 177 nm.