TaB2 powders synthesis by reduction of Ta2O5 with B4C

Abstract

This work reported the synthesis of submicrometric TaB2 powders by reduction of Ta2O5 using B4C in vacuum. The starting mixture with a molar ratio of B4C/Ta2O5=1.57 completely converted to a mixture of TaB2 and B2O3 at 1100°C, whereas that converted to a mixture of TaB2, Ta3B4 and minor TaB at 1550°C due to the boron loss resulting from the formation of gaseous boron-rich oxides. Microstructure observation showed the TaB2 and Ta3B4 particles had small equiaxed and large plate-like shapes, respectively. Excess B4C should be added to compensate for the boron loss. Phase-pure TaB2 powders with equiaxed shape were synthesized at 1550°C with a molar ratio of B4C/Ta2O5=1.90. The particle size and oxygen content of TaB2 powders were ~0.7µm and ~0.80wt%, respectively.