| Summary: | In this study, TiN–TiB<sub>2</sub>–hBN composite ceramics were prepared via reactive hot pressing using TiN and amorphous B powders as raw materials. Different sintering temperatures and composition ratios were studied. The results show that the 70 vol% TiN–17.6 vol% TiB<sub>2</sub>–12.4 vol% hBN ceramic composites obtained ideal comprehensive properties at 1600 °C. The relative density, Vickers hardness, bending strength, and fracture toughness were 99%, 11 GPa, 521 MPa, and 4.22 MPa·m<sup>1/2</sup>, respectively. Densification was promoted by the highly active reaction product TiB<sub>2</sub>, and the structural defects formed in the grains. Meanwhile, the good interfacial bonding between TiN and TiB<sub>2</sub> grains and the uniform dispersion of ultrafine hBN in the matrix contributed to the excellent bending strength. Moreover, the toughening mechanism of crack deflection and grain pull-out improved the fracture toughness.
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