Preparation of high-hardness titanium oxycarbonitride ceramic and its composite with TiB2

Dense titanium oxycarbonitride (TCNO) ceramic and its composites with in-situ grown and direct-added TiB2 particles were prepared by powder sintering. The TCNO ceramic is a single-phase solid solution and its com-posites mainly contain TCNO phase and TiB2 phase. The in-situ grown TiB2 grains have an average size about 2.3 mu m and the plate-like morphology, and the direct-added TiB2 form spherical grains with the average grain size about 2.0 mu m. Meanwhile, the introduction of the secondary phase of TiB2 reduces the TCNO grain size. Compared to the hardness of pure TCNO ceramic about 27.7 GPa, the hardness of its composites is increased to above 30 GPa. The outstanding hardness of TCNO ceramic and its composites is attribute to the synergistic effect of solid-solution reinforcement and the introduction of secondary phase of TiB2.