Synthesis of TiB₂-Tic composite powder by SHS reduction process

The mechanism of chemical reaction and microstructure formation process of B₂O₃TiO₂-Mg-C system were investigated in this paper. The results show that TiB₂-TiC ceramic powder can be obtained by SHS from B₂O₃-TiO₂-Mg-C system. The results of analysis of different thermal analysis (DTA) and X-ray diffraction (XRD) show the following thermal processes of B₂O₃TiO₂-Mg-C system: B₂O₃ is reduced to B and TiO₂ is reduced to Ti. Metal Mg is melted at 650°C. At 680°C the reaction between B and Ti nearly finish and the formation of TiC from the reaction of Ti and C begin. TiO₂ is reduced to element Ti step by step through the following way: TiO₂→TiO→Ti. TiB₂-TiC composite powder with particle size of 45 percent under 1 μm and 87 percent under 3 μm is obtained after MgO, the unwanted phase, was removed by leaching in hydrochloric acid. Results of SEM micrographs of TiB₂-TiC ceramic multiphase powder show that the particle size is much smaller than that of single phase TiB₂ or TiC produced by the same methods. The mole ratio of Ti and C in TiC is 1:0.7483.