Carburization of Tantalum Metal Powder Using Activated Carbon

TL;DR

Researchers used activated carbon to produce tantalum carbide powder, achieving high-quality results under vacuum conditions.

Contribution

The study demonstrates that activated carbon is more effective than graphite for carburizing tantalum metal powder.

Findings

Activated carbon significantly increased carbon uptake compared to graphite due to higher porosity and surface reactivity.

X-ray diffraction confirmed the progression of carbide phases from Ta to Ta2C and finally to TaC.

SEM analysis revealed fine particle formation on the surface with increased carbon content.

Abstract

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 Ta2O5, 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 Ta2C 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.

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