A facile synthesis method for in situ composites of TiB₂/B₄C and ZrB₂/B₄C

In situ composite particles of titanium diboride/boron carbide (TiB₂/B₄C) and zirconium diboride/boron carbide (ZrB₂/B₄C) were synthesized from low-cost boric acid and sucrose-based precursor solution with the addition of titanium (IV) ethoxide and zirconium oxynitrate, respectively. The reaction was conducted at 1650 °C for 90 min under Ar (240 L/h) + H₂ (10 L/h) gas flow. The characterization of the resultant powders was performed in terms of phases in particles and their microstructures and elemental mapping. The particles synthesized from Ti-based precursor comprised hexagonal TiB₂ platelets and polyhedral B₄C particles while those synthesized from Zr-based precursor comprised equiaxed polyhedral ZrB₂ particles with slightly elongated polyhedral B₄C particles. As Ti and Zr concentrations increased in the precursor solution, the hexagonal lattice parameters of B₄C and its corresponding lattice volume decreased. Additionally, the results provide evidence that the solid solubility of C in TiB₂ and ZrB₂ phases is relatively low.