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

The reaction mechanism of TiB2 synthesized by carbothermal reduction is unclear due to a lack of thermodynamic research. In this work, the phase diagrams of TiO2-B2O3-C system were analyzed at a large temperature range (900-1800 degrees C), illustrating that Ti4O7, Ti3O5, 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 TiB2 were discussed, respectively. Based on the thermodynamic research, the reaction mechanism of TiO2-B2O3-C system was proposed and verified by experimental research at 900-1500 degrees C. X-ray-pure TiB2 powder was synthesized at 1500 degrees C for 30 min and the possible reaction mechanism could be divided into three stages: TiO2(anatase)-> TiO2(rutile)-> Ti3O5, TiC -> TiB2.