Synthesis of TiC–TiB ₂ composite powders via carbothermal reduction and its reaction mechanism

Titanium carbide–titanium diboride (TiC–TiB2) composite powders were synthesised through a carbothermal reduction method by using titanium dioxide, boric acid, and different carbon sources (namely, carbon black, sucrose, and glucose) as starting materials. The thermal decomposition behaviour of the precursors was studied by thermogravimetry–differential thermal analyser. Phase compositions and morphologies of the synthesised products were characterised by X-ray diffractometer and scanning electron microscope. When n(Ti):n(B):n(C) = 1.0:2.5:5.0, the blended stock mainly formed TiB2 with sucrose or glucose as a carbon source, whereas the stock produced TiC when carbon black was the source. At an optimum reaction temperature, the particles of the powders synthesised from carbon black as a carbon source were the smallest at approximately 100 nm. With increasing amount of boric acid in the precursor, the morphologies of the samples changed into less spherical particles, and more flaky grains and small particles with irregular structures were observed.