In Situ Synthesis of TiB2-TiC0.8-40vol%SiC by Hot Pressing
TiB2-TiC0.8-40vol%SiC multiphase ceramics were prepared by in-situ hotpressing sintering. The phase composition and microstructures of the materials were characterized by optical mic- oscope, X-ray diffraction and scanning electron microscopy. The effects of sintering temperature on the phases, microstructures and mechanical properties of the ceramics were investigated. The results show that density, bending strength and fracture toughness of the ceramics are increased with the elevation of sintering temperature (1800-1950°C). High densified TiB2-TiC0.8-40vol%SiC multipha- se ceramics and optimized microstructure is obtained by sintering at 1900°C, in which the uniform distribution of lath-shape TiB2 and bulk TiC0.8 grains can be observed obviously. Nano-SiC particles distributed dispersively in the TiB2 and TiC0.8 grains and at boundaries. The Vickers hardness, fract- ure toughness, flexural strength and electrical conductivity of the TiB2-TiC0.8-40vol%SiC multipha- se ceramics sintered at 1900°C are 24.055GPa, 8.27±1.0MPa∙m1/2, 516.69MPa and 2.2×106S∙m-1, respectively. However, up to 1950°C, TiB2 and TiC0.8 grains gradually grew up, the bending stren- gth of multiphase ceramics was decreased greatly. In addition, TiB2, TiC0.8 and SiC particles were incorporated together to improve the particulate strength and toughness of composite material by the synergistic mechanism effects among the crystal phases in the multiphase ceramics, such as crack deflection, grain’s pull-out and fine-grain toughening.