Preparation and characterization of tantalum carbide (TaC) ceramics

Tantalum carbide (TaC) ceramics without sintering additives or transition metals were consolidated within a sintering temperature range of 1350-1900 degrees C using a resistance-heated hot-pressing technique. Dense TaC ceramics having relative density values above 98 vol.% were obtained at temperatures exceeding 1375 degrees C, and only the TaC phase with stoichiometric or closely stoichiometric compositions was detected in the sintered bodies. The average grain size of the TaC grains increased significantly with sintering temperature. Young's modulus for dense, pure TaC ceramics (relative density > 98 vol.%) ranged from 531 to 549 GPa; a fully dense TaC ceramic was estimated to have a Young's modulus value of 558 GPa. The hardness of the dense TaC ceramic was similar to 14 GPa, regardless of the TaC average grain size, and the fracture toughness was similar to 4 MPa m(0.5). The electrical resistivity of the TaC ceramic was 0.36 mu Omega mat 20 degrees C and increased linearly with temperature. The thermal conductivity of the TaC ceramic, 27.9 W (m K)(-1) at 25 degrees C, increased with temperature. (C) 2015 Elsevier Ltd. All rights reserved.