Chemical vapor deposition of carbon on particulate TiO2 from CH4 and subsequent carbothermal reduction for the synthesis of nanocrystalline TiC powders

The present study aims to investigate chemical vapor deposition of carbon from CH4 on TiO2 particles and to establish optimal conditions for the synthesis of nanocrystalline TiC powders. Mass measurements, XRD, HR-TEM and SEM were used to characterize the products at various stages of the reactions. Oxide particles gained mass rapidly at 1300 K under CH4 atmosphere and were coated with thin pyrolytic carbon layers of 10-20 nm. XRD analysis showed that the coated powders consisted of C, TiO2 and titanium sub-oxides. The powders containing ∼33 ± 2 wt% carbon were used for the carbothermal reduction of TiO2 to TiC at 1600-1800 K under Ar flow. Lattice constant and mass loss of the samples increased to the levels of TiC with temperature and time. Nearly pure TiC powders with a mean particle size of ∼125 nm were synthesized at 1750-1800 K within 30 min.