Mechanical properties and microstructure of TiB2–TiC composite ceramic cutting tool material

TiB₂–TiC composite ceramic cutting tool material was prepared by sintering during hot-pressing in vacuum. The effects of nano-scale Ni and Mo additives and sintering heating rate on mechanical properties and grain characteristics were investigated. TiB₂ and TiC grains exhibited prismatic and equiaxed shapes respectively. The diameter and aspect ratio of prismatic TiB₂ grains were influenced by nano-scale Ni/Mo additives. A higher heating rate could cause a higher aspect ratio of prismatic TiB₂ grains. The good mechanical properties of TN1((TiB₂–TiC)/Ni composite ceramic sintered at a heating rate of 50 °C/min) were ascribed to a relatively fine and homogenous microstructure. And a brittle B₄MoTi solid solution phase and wider distribution of grain size induced the lower flexural strength of TNM2((TiB₂–TiC)/(Ni,Mo) composite ceramic sintered at heating rate of 100 °C/min), but the higher aspect ratio of TiB₂ grains could prevent cracks from propagating and ameliorated the fracture toughness. The optimum resultant mechanical properties were obtained by (TiB₂–TiC)/Ni composite ceramic sintered at a heating rate of 50 °C/min.