Densification kinetics and mechanical properties of tantalum carbide.

Sintering kinetics and densification of tantalum carbide (TaC) based ultra-high temperature ceramics (UHTC) processed using spark plasma sintering (SPS) were investigated. Samples sintered in the temperature ranging from 1600 °C to 2300 °C for 15 min under uniaxial pressure of 50 MPa showed increasing densification (~77% to 99% from 1600 °C to 2300 °C) accompanied by substantial grain growth (~0.57 μm to ~4.05 μm). Below 1900 °C, the densification mechanism was grain-boundary sliding with an apparent activation energy of 97.3 ± 10.2 kJ/mol. However above 1900 °C, the activation energy was found to be 232.7 ± 19.6 kJ/mol with grain boundary diffusion to be an active densification mechanism. The flexural strength (from 161.3 ± 10.4 MPa to 326.5 ± 10.5 MPa) and elastic modulus (from 375.7 ± 3.1 GPa 535.4 ± 4.7 GPa) was observed to increase with the increasing sintering temperature. The study explicitly establishes that the dense bulk TaC ceramic can be produced by SPS in a shorter time and lower sintering temperature, while maintaining the compositional stoichiometry. [ABSTRACT FROM AUTHOR]