SiC-TiC composite powders were synthesised in argon atmosphere by a carbothermal reduction method using silica sol, TiO2, and different carbon sources (i.e., graphite and starch) as the raw materials. The effects of carbon source types and reaction temperatures on the phase composition, particle size distribution, and microstructure of SiC-TiC composite powders were investigated. The reaction mechanism of SiC-TiC composite powders was also discussed. Results showed that SiC-TiC composite powders can be synthesized under optimum conditions (i.e., 1600 o C for 2 hrs using graphite as carbon source and 1550 o C for 2 hrs using starch as carbon source). The SiC-TiC composite powders prepared at 1600 o C comprised a small amount of large-sized tabular grains, a large number of fine irregular rod-like and approximately spherical particles 200- 400 nm in size using graphite as carbon source. The SiC-TiC composite powders prepared at 1550 o C were composed of flaky particles, spherical particles (~ 100-200 nm), and whiskers (50-200 nm in diameter) using starch as carbon source. The growth mechanism of SiC whiskers synthesised in powder samples followed the vapor-solid mechanism.

Keywords: Graphite, Starch, SiC-TiC, Composite powders, Synthesis, Mechanism.