Carbon Loss and Control for WC Synthesis through a Self-propagating High-Temperature WO3-Mg-C System

Mono-tungsten carbide (WC) synthesis via a cost-effective self-propagating high-temperature synthesis (SHS) process has attracted considerable research and development interest in recent years. The WO₃-Mg-C system is widely used in SHS owing to its intensive exothermic characteristics, making it ideal for this process. Excess carbon is required to increase carburization efficiency without the use of additives. However, excessive free carbon negatively affects synthesis quality. This study investigated the effects of excess carbon on a WO₃-Mg-C system and its effective control. To verify the hypothesized carbon-loss reaction induced by the carbothermal reduction of MgO, we decreased the combustion temperature (T_C) by adding diluents with different properties, such as NaCl and excess Mg. The decreased T_C and increased NaCl and MgO contents promoted particle refinement by suppressing particle growth during synthesis.