Thermodynamic research of the reaction mechanism for TiB2 synthesized by carbothermal reduction

The reaction mechanism of TiB 2 synthesized by carbothermal reduction is unclear due to a lack of thermodynamic research. In this work, the phase diagrams of TiO 2 -B 2 O 3 -C system were analyzed at a large temperature range (900–1800 °C), illustrating that Ti 4 O 7 , Ti 3 O 5 , and TiC were the main intermediate products. According to the Gibbs free energy minimum principle, the synthesis pathways of the main intermediate products and the target product TiB 2 were discussed, respectively. Based on the thermodynamic research, the reaction mechanism of TiO 2 -B 2 O 3 -C system was proposed and verified by experimental research at 900–1500 °C. X-ray-pure TiB 2 powder was synthesized at 1500 °C for 30 min and the possible reaction mechanism could be divided into three stages: TiO 2 (anatase)→TiO 2 (rutile)→Ti 3 O 5 , TiC →TiB 2 .