Properties of B₄C-TiB₂ ceramics prepared by spark plasma sintering

By doping titanium hydride (TiH₂) into boron carbide (B₄C), a series of B₄C+x wt% TiH₂ (x = 0, 5, 10, 15, and 20) composite ceramics were obtained through spark plasma sintering (SPS). The effects of the sintering temperature and the amount of TiH₂ additive on the microstructure, mechanical and electrical properties of the sintered B₄C-TiB₂ composite ceramics were investigated. Powder mixtures of B₄C with 0-20 wt% TiH₂ were heated from 1400 ^°C to 1800 ^°C for 20 min under 50 MPa. The results indicated that higher sintering temperatures contributed to greater ceramic density. With increasing TiH₂ content, titanium diboride (TiB₂) formed between the TiH₂ and B₄C matrix. This effectively improved Young's modulus and fracture toughness of the composite ceramics, significantly improving their electrical properties: the electrical conductivity reached 114.9 Scm ^-1 at 1800 ^°C when x = 20. Optimum mechanical properties were obtained for the B₄C ceramics sintered with 20 wt% TiH₂, which had a relative density of 99.9 0.1%, Vickers hardness of 31.8 GPa, and fracture toughness of 8.5 MPa m^{1 / 2}. The results indicated that the doping of fine Ti particles into the B₄C matrix increased the conductivity and the fracture toughness of B₄C.