Abstract

Ultrafine TaC-5%Co composite powders were synthesized by spray conversion process using tantalum oxalate solution and cobalt nitrate hexahydrate(Co((NO_3)_2 . 6H_2O). The phase of Ta-Co oxide powders had amorphous structures after calcination below 500°C and changed Ta_2O_5, TaO_2 and CoTa_2O_6 phase by heating above 600°C. The calcined Ta-Co oxide powders were spherical agglomerates consisted of ultrafine primary particles <50 nm in size. By carbothermal reaction, the TaC phase began to form from 900°C. The complete formation of TaC could be achieved at 1050°C for 6 hours. The observed size of TaC-Co composite powders by TEM was smaller than 200 nm.

• Keywords: Tantalum oxalate;Tantalum carbide;Ultrafine;Synthesis;