Synthesis of Submicron-Sized TiB₂ Powders by Reaction of TiC, B₄C, and Ca in Molten CaCl₂

Submicron-sized TiB₂ powders (300 nm-1 μm) were prepared by the reaction of TiC, B₄C, and Ca assisted by molten CaCl₂. The optimal reaction procedure (1200 °C and 25 wt.% CaCl₂ + 25 wt.% Ca) was obtained by exploring the effects of the boronization reaction temperature and the addition of an amount of CaCl₂. It was found that the introduction of CaCl₂ not only promoted the reaction but also effectively inhibited the volatilization of excess Ca. Furthermore, SEM images of the products showed that the morphology and particle size of TiB₂ were inherited from the carbothermal reduction product TiC, which was dominated by the "template/growth" mechanism. The process of the boronization reaction was that B atoms migrated from B₄C and replaced the C atoms in the lattice of TiC.