Synthesis of a Fine (Ta0.8,Hf0.2)C Powder from Carbide or Oxide Powder Mixtures

Tantalum hafnium carbide ((Ta-0.8,Hf-0.2)C) powders were successfully synthesized using a modified spark plasma sintering (SPS) apparatus with TaC/HfC or Ta2O5/HfO2/C starting materials. The (Ta-0.8,Hf-0.2)C obtained from the carbides had a finer particle size of 220 nm, whereas those obtained from the oxides had less contamination during the milling process (0.35 wt%) than the other case. Particle coarsening of the solid-solution phase was effectively suppressed by using a modified SPS apparatus because of the fast heating/cooling rate. High-energy ball milling promoted a solid-solution reaction for the formation of (Ta-0.8,Hf-0.2)C by refining the size and inducing the homogeneous mixing of the starting materials. By the combination of the fast heating and high-energy ball milling, fine tantalum hafnium carbide powders with low contamination were successfully synthesized.