Reaction Process of WC Prepared under a CO Atmosphere in a Fluidized Bed

Combined with thermodynamic analysis and various characterizations, such as X-ray diffraction, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and so on, the reaction process of WC prepared from WO2.72 in a fluidized bed has been investigated under a CO atmosphere in the range of 800–1000 °C. The phase analysis results indicate that WO2.72 undergoes different reaction paths to form tungsten carbide in different temperature ranges. Especially, when the reaction temperature is in the range of 900–950 °C, the reaction process follows the following reaction route: WO2.72 → WO2 → W2C → WC, while no W2C is produced in the reported literatures. XPS and TEM results show that solid carbon can be formed by the decomposition of carbon monoxide in both high- and low-temperature regions. The reaction process from WO2.72 to WO2 or W mainly depends on the gas–solid heterogeneous reaction in the initial stage. In the deep reduction or carbonization stage, both gas–solid heterogeneous reaction and solid-phase homogeneous reaction are included in the lower temperature region, while the formation of WC mainly depends on the homogeneous reaction between solid carbon and metallic tungsten in the higher temperature region.