Highly electro-conductive B₄C–TiB₂ composites with three-dimensional interconnected intergranular TiB₂ network

To achieve lightweight B₄C-based composite ceramics with high electrical conductivities and hardness, B₄C–TiB₂ ceramics were fabricated by reactive spark plasma sintering (SPS) using B₄C, TiC, and amorphous B as raw materials. During the sintering process, fine B₄C–TiB₂ composite particles are firstly in situ synthesized by the reaction between TiC and B. Then, large raw B₄C particles tend to grow at the cost of small B₄C particles. Finally, small TiB₂ grains surround large B₄C grains to create a three-dimensional interconnected intergranular TiB₂ network, which is beneficial for an electro-conductive network and greatly improves the conductivity of the ceramics. The effect of the B₄C particle size on the mechanical and electrical properties of the ceramics was investigated. When the particle size of initial B₄C powders is 10.29 µm, the obtained B₄C–15 vol% TiB₂ composite ceramics exhibit an electrical conductivity as high as 2.79×10⁴ S/m and a density as low as 2.782 g/cm³, together with excellent mechanical properties including flexural strength, Vickers hardness (HV), and fracture toughness (K_IC) of 676 MPa, 28.89 GPa, and 5.28 MPa·m^1/2, respectively.