Rapid sintering of TiB₂ ceramics using Co as sintering aid under high pressure condition

The improved TiB₂ ceramics were obtained in sintering process at the pressure of 5.5 GPa and temperature of 1550 °C in presence of metallic Co powder. The effect of Co content (ranging from 0 wt.% to 10.0 wt.%) on the phase composition, density, microstructure, Vickers hardness and thermal conductivity of TiB₂ ceramics was analyzed. A small amount of new phase Co₂B has been created in the reaction of TiB₂ and Co. The relative density of sintered TiB₂ ceramics reached 98.1 %. When the mass fraction of Co increased, the porosity increased, while the hardness first increased and then decreased. The maximal Vickers hardness values were equal to 33.3 GPa or 28.2 GPa when the used load was of 4.9 N or 9.8 N, respectively. The highest reached value of thermal conductivity was 88.9 W˙m⁻¹ ˙ K⁻¹. The dense TiB₂ ceramics with improved hardness and thermal conductivity were ascribed to the high pressure sintering method and Co sintering aid. High pressure sintering method provides a new way for the preparation of ceramics materials.