STUDY ON THE STRUCTURE AND PROPERTIES OF TiB₂-TiC MULTIPHASE CERAMICS

By hot-pressing method, TiB₂-TiC multiphase ceramics were fabricated from TiB₂-TiC composites powders under the following sintering conditions: sintering temperature: 1700℃ and 1800℃, pressure: 30MPa, sintering time: 60min. The relative density, the hardness and fracture toughness of TiB₂-TiC multiphase ceramic at room temperature were 99.8%, 93.2HRA and 5.53MPa·m^1/2 respectively. The residual porosities and dislocation in sintered ceramics went against the performance. The microstructure of TiB₂-TiC multiphase ceramics from composite powders had smaller and more symmetrical grains than the TiB₂-TiC ceramics sintered from the mixtures of TiB₂ and TiC powders. The elements of B, C and Ti at the interface of TiB₂ and TiC were distributed gradually. There were no impurities at the interface and the bonds between phases were strong, which probably has relation to the higher properties of TiB 2-TiC multiphase ceramics. The growth of TiB₂ in different crystal directions was different in TiB₂-TiC multiphase ceramics.