Synthesis of ultrafine titanium carbonitride powders

Titanium-carbonitride-based materials are very hard materials with increasing technical importance. They are mainly used in composites with various metal carbides and/or metallic binders (cermets) for metal cutting operations. These applications call for the synthesis of titanium carbonitride powders with homogeneous chemical composition, as small as possible grain size and narrower grain size distribution. Nowadays on the market, only commercial submicrometric (0.5-2 um) powders are available. Starting from blends of nanosize commercial TiN or TiO2 powders mixed with different carbon powders (carbon black, active carbon), this study aimed to set up a low-cost process to synthesize fine and pure TiC1X NX powders with an X value close to 0.5. The morphology of the as-obtained powders and the progress of the reaction were investigated by scanning electron microscopy and X-ray diffraction. The stoichiometric parameter X was estimated on the basis of a TiC1X NX Raoultian solid solution together with Vegard's rule. The results are presented and discussed to assess relations between powder characteristics and processing conditions. The most encouraging results were obtained using a mixture TiN 10 wt%C (carbon black) processed at 1430 °C for 3 h under flowing argon. Regularly shaped particles with limited agglomeration ranged from 100 to 300 nm and an X value close to 0.5