(Hf0.99Ta0.01)B2-based ceramics prepared by pressureless sintering with boron additive

Abstract

HfB2-based ceramics were fabricated by pressureless sintering with the combination of TaB2/B. It was found that the incorporation of TaB2 reduced the particle size of the HfB2-based powders prepared by borothermal reduction, but the densification of pressureless sintered HfB2 ceramics was slightly improved (from 63.2% to 69.4%). It was revealed that the combination of TaB2 and 5 wt% B could dramatically improve the sinterability of HfB2 ceramics. In combination of TaB2 and B, the relative density of HfB2-based ceramics increased significantly from 63.2% to 92.3%, and further reached to 97.2% with increasing fraction of TaB2. Finally, (Hf0.99Ta0.01)B2-5 wt% B ceramics displayed the favorable mechanical properties (Hardness: 18.1 ± 0.6 GPa).