The effects of different molten salt composition on morphology and purity of ZrB2 powder obtained via direct molten salt reaction method

Abstract

Zirconium Diboride (ZrB2) powder was synthesized at low temperature via a Direct Molten Salt Reaction (DMSR) method. The influence of different salt compositions including eutectic mixture of (KF-NaF), (KF-KCl) and (KCl-NaCl) on the morphology and purity of the reaction products was studied. The obtained samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Furthermore, the formation mechanism of ZrB2 was investigated by DTA/TG. The results show that alongside eutectic mixture of chloride salt, ZrB2 powder can be obtained with eutectic mixture of fluoride salt. In addition, obtained ZrB2 powder without additional salt has hexagonal prism morphology, whereas ZrB2 particles prepared with eutectic mixture of fluoride salt have higher purity and particle size and hexagonal morphology as well. Synthesized ZrB2 Powder in chlorofluoride salt has lower particle size and purity and non-uniform morphology. Synthesized ZrB2 powder is different from starting material in term of morphology and particle size therefore the dissolution–precipitation mechanism may play a dominant role on the synthesis of ZrB2 during DMSR process.