New Borothermal Reduction Route to Synthesize Submicrometric ZrB 2 Powders with Low Oxygen Content

The ZrB 2 powders with submicrometric particle size and low oxygen content were synthesized by a new borothermal reduction route using ZrO 2 and excess boron as raw materials. The conventional process only contained the borothermal reduction of ZrO 2 with boron at 1550°C. By exploring the mechanism of ZrB 2 particle coarsening during conventional process, a new borothermal reduction route was proposed. This route included the borothermal reduction of ZrO 2 with boron at 1000°C, washing by hot water, and the removal of residual boron oxides at 1550°C, namely, two‐step reduction plus intermediate water‐washing ( RWR ). Using conventional process, the particle size and oxygen content of ZrB 2 powder were about 2–3 μm and 0.68 wt%, respectively. Based on the new route, the particle size and oxygen content of ZrB 2 powder were about 0.4–0.7 μm and 0.40 wt%, respectively.