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.