Reaction of TiC with SiCl4 vapor with formation of SiC-TiC composites

The reaction of TiC grains with SiCl4 vapor was carried out in Ar at 1000-1600 degrees C to produce TiC-SiC composite powders. The compositions of these powders were controlled by controlling the conversion to SiC, which depends on the reaction temperature, The phases formed by the solid-gas reaction were identified by X-ray analysis (XRD) and the molar ratio of SiC to TiC in the powder was estimated from the area ratios of the respective XRD peaks. The reaction begins at about 1100 degrees C and its rate increases with temperature to 1600 degrees C, at which 92% SiC is formed. The morphology of the TiC-SiC composites was observed by scanning electron microscopy and transmission electron microscopy and a reaction mechanism is deduced from the above results and thermodynamic considerations. TiC-SiC composites were densified by spark plasma sintering at 1750 degrees C and 40 MPa to the relative density 92-96% and a Vickers hardness of 1700-1900 Hv. (C) 2009 Published by Elsevier Ltd.