Nano‐Hafnium Diboride Powders Synthesized Using a Spark Plasma Sintering Apparatus
Nano‐hafnium diboride powder was synthesized by boro/carborthermal reduction process of HfO2 using a spark plasma sintering (SPS) apparatus. The agglomerated product was found to be 1–2 μm
in size, which was composed with small primary particles of 100–200 nm in size. The particle size of HfO2 played an important role to produce the nano‐boride powder. In addition, the grain growth of HfB2
could be effectively suppressed by using SPS due to the fast heating rate. The synthesized powder had a low oxygen content (~0.66 wt%). Excessive B4C and C were necessary during the boro/carborthermal reduction in HfO2
process because of the volatilization of boron as a form of B2O3 and the reduction in residual HfO2.