Process Study on Preparation of TiC by Reduction–Carburization of TiO2 in CH4-Ar Mixed Gas

Methane (CH4) was employed as a carbon source for the reduction and carburization of TiO2 via a gas-phase infiltration process to synthesize titanium carbide (TiC). The highly reactive and diffusible carbon species derived from CH4 decomposition enable a significant reduction in both reaction time and temperature compared with conventional carbothermal reduction methods. The phase evolution during the CH4-driven reduction–carburization of TiO2 was analyzed, and the effects of CH4 volume fraction, reaction temperature, and reaction time on the carburization efficiency were systematically investigated, with the phase composition and microstructure of the products also characterized. The optimal conditions in a CH4-Ar system were found to be 10%CH4–90%Ar at 1270 °C for 8 h, yielding a carburization efficiency of 79.1% for TiO2 pellets. Increasing the CH4 proportion led to more severe carbon deposition, with deposited carbon adhering to the pellet surface and clogging the internal pores. Raising the temperature promoted the reduction–carburization reaction, but excessive acceleration of CH4 cracking above 1270 °C caused carbon accumulation on the TiO2 surface, forming a carbon shell that lowered the carburization efficiency. Prolonging the reaction time was beneficial for achieving a higher degree of carburization.