Carburization of Tantalum Metal Powder Using Activated Carbon.

Tantalum carbide (TaC) is a highly refractory material with a melting point of 4153 K, making it attractive for applications requiring excellent hardness and thermal stability. In this study, we investigated the carburization behavior of high-purity tantalum metal powder synthesized by magnesium thermal reduction of TaO, using activated carbon and graphite as carbon sources under high vacuum. Carburization was conducted at 1100-1400 °C for durations of 5-20 h. Carbon contents were analyzed via combustion analysis, and activation energies were calculated based on Arrhenius plots. The results showed that the activated carbon significantly enhanced carbon uptake compared to graphite due to its higher porosity and surface reactivity. The formation and transformation of carbide phases were confirmed via X-ray diffraction, revealing a progression from Ta to TaC and eventually to single-phase TaC with increasing carbon content. Scanning electron microscopy (SEM) analysis showed that fine particles formed on the surface as carbon content increased, indicating local nucleation of TaC. Although the theoretical carbon content of stoichiometric TaC (6.22 wt.%) was not fully achieved, the near-theoretical lattice parameter (4.4547 Å) was approached. These findings suggest that activated carbon can serve as an effective carburizing agent for the synthesis of TaC under vacuum conditions.