Low-temperature synthesis and sinterability of high-purity submicron TiB₂ powder via microwave-assisted carbothermal reduction

Microwave-assisted carbothermal reduction has been innovatively developed for the low-temperature synthesis of high-purity submicron TiB2 powders. The thermodynamic research of TiO2-B4C-C system and relevant reactions showed that suitable excess addition of B4C was required to compensate for the boron source evaporation loss. The effect of excess addition of B4C (0 -15 wt%) and synthesis temperature (1350 -1550 degrees C) on the phase composition, purity, and morphology of the products have been investigated. Submicron TiB2 powders (0.75 mu m) with high-purity (0.36% residual C and 0.53% O) were successfully synthesized at 1450 degrees C for 20 min under microwave assistance with TiO2, excess 5 wt% B4C, and carbon black. Additionally, the as-synthesized TiB2 powders after spark plasma sintering at 2000 degrees C for 15 min showed a relatively higher sinterability, namely increased at 7.7% relative density of sintered ceramic when compared with the commercially available powders owing to the lower O content and submicron-scale size.