Novel synthesis of ZrB2 powder by low temperature direct molten salt reaction

Zirconium diboride (ZrB2) powder was successfully synthesized at low temperature via a novel direct molten salt reaction (DMSR) route using K2ZrF6, KBF4 and Al. The influence of temperature (600–900 °C), reaction time (1, 2 and 4 h) and molar ratio of Al/salt (1, 2 and 10) on the morphology and purity of the product was studied. The obtained samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The average size of ZrB2 particles is more than 1 μm with hexagonal plate-like morphology. The role of Al is crucial for synthesis of ZrB2 and the yield of product depends directly on the Al content. Results in terms of purity and morphology of the products reveal that a temperature of 800 °C, a reaction time of 2 h and a 10:1 M ratio of Al to salt were the optimum synthesis conditions. Under these conditions, hexagonal plate-like ZrB2 powder was synthesized.