Novel Synthesis of ZrB 2 Powder Via Molten‐Salt‐Mediated Magnesiothermic Reduction

Zirconium diboride ( ZrB 2 ) powder was synthesized at a low temperature via a molten‐salt‐mediated reduction route using ZrO 2 , Na 2 B 4 O 7 and Mg powders as starting raw materials. By using appropriately excessive amounts of Mg and Na 2 B 4 O 7 to compensate for their evaporation losses, ZrO 2 could be completely converted into ZrB 2 after 3 h at 1200°C. In addition, the formation of undesirable Mg 3 B 2 O 6 could be effectively avoided. As‐prepared ZrB 2 powders were phase pure, 300–400 nm in size and generally well dispersed. SEM images showed that to a large extent the reactively formed ZrB 2 retained the morphology and size of the starting ZrO 2 . The salt melt formed from MgCl 2 and Na 2 B 4 O 7 at test temperatures is believed to be responsible for the reduced synthesis temperature and good dispersion of the final ZrB 2 product powder.