Synthesis of TiC-TiB2 composite powders from carbon coated TiO2 precursors

Submicron TiC-TiB2 composite powders were synthesized by carbo/borothermal reductions from a novel carbon coated TiO2 precursors method. Reactants were also mechanically mixed for comparison. Precursors and conventionally mixed powders were reacted from 1100 to 1500 °C for 2 h in flowing argon at 1 L/min. Phase evolution, thermodynamic analysis, microstructures, and surface areas were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET) surface area analyzer, respectively. Products synthesized from precursors had high purity of TiC-TiB2 mixture, fine particle size, narrow size distribution, regular shape, loose agglomeration, and high surface area. Powders with different compositions were also prepared by controlling the ratio between reactants. The sintering tests demonstrated that produced powders can be sintered to a 99.6% relative density using 5 wt% nickel additives at 1550 °C for 2 h in flowing argon atmosphere.