Synthesis of Ultra-fine ZrB{sub}2 Powder by Borothermal Reaction under High Heating Rate

摘要

Ultra-fine zirconium diboride (ZrB{sub}2) powders have been synthesized by borothermal reduction reaction, using zirconium oxychloride (ZrOCl{sub}2·8H{sub}2O) as the precursors of zirconia. The thermodynamic variation in the amorphous ZrO{sub}2-B system was studied by thermogravimetric and differential thermal analysis (TG-DTA). The precursors containing amorphous ZrO{sub}2 and B were heat-treated under a high heating rate. It is shown that the borothermal reaction can be completed at a relatively low temperature (～950°C) and short duration (～5min) under a heating rate of 200°C/min. The synthesized powders have an average crystalline size of 300nm with oxygen content less than 2.62wt%.