硼化钛对无压烧结碳化硼结构和性能的影响

B₄C-TiB₂ multi-phase ceramics were prepared in a pressureless vacuum sintering-furnace at different temperatures with TiB₂ added into B₄C matrix as a second phase substance, and C and Si as sintering aids. The density, hardness, bending strength and fracture toughness of the samples were determined. The influences of composition ratio of B₄C-TiB₂ and sintering temperature on the microstructure and mechanical properties of the multiphase ceramics were investigated by X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy. The toughening mechanism of ceramics was discussed. The results show that the optimum density and comprehensive mechanical properties of the multiphase ceramics (i.e., the relative density of 94.59%, the Rockwell hardness of 87.62, the bending strength of 182MPa, and the fracture toughness of 3.97 MPa•m^1/2 can be obtained at a sintering temperature of 2200℃ and TiB₂ content of 30%. The TiB₂ particles can effectively nail the grain boundary, inhibit the growth of B₄C grains and play a role in fine-grain strengthening. The TiB₂ and laminated graphite phase hinder the crack growth, thus improving the fracture toughness.