Synthesis of ultrafine TaC-5Â wt.% Co composite powders by the spray-carbothermal process

Ultrafine tantalum carbide (TaC)-5 wt.% Co composite powders were synthesized by a spray-carbothermal process, which includes (i) preparation of precursor powder by spray drying of a liquid solution of tantalum oxalate and cobalt nitrate hexahydrate, (ii) calcination to evaporate volatile components in the precursor powder and synthesis of nanostructured tantalum-cobalt composite oxides and (iii) ball milling with carbon, and subsequent carbothermal reaction in hydrogen. The formation temperature of TaC in this process (1050 °C) is significantly lower than that in the conventional method (1500 °C). The observed particle size of TaC-Co composite powders was smaller than 200 nm.