Sintering and densification mechanisms of tantalum carbide ceramics

Dense tantalum carbide (TaC) ceramics were prepared using TaC nanopowder via spark plasma sintering (SPS). The effects of the sintering temperature and applied pressure on the densification and grain growth behaviour of TaC ceramics were investigated. The results showed that high temperature and pressure promoted sintering densification, while their increase caused an increase in the grain size of TaC ceramics. A highly dense TaC ceramic (-97.19%) with a fine grain size of 2.67 mu m was obtained by sintering at 1800 degrees C for 10 min under 80 MPa. The Vickers hardness, Young's modulus and fracture toughness were 15.60 GPa, 512.66 GPa and 3.59 MPa.m1/2, respectively. The densification kinetics were investigated using a creep deformation model. Diffusion and grain boundary sliding were proven to be the dominant densification mechanisms based on the stress and grain size exponents combined with the microstructural characteristics. The apparent activation energy of the mechanism controlling densification was 252.94 kJ/mol.

Automated summary

Dense tantalum carbide ceramics were prepared via spark plasma sintering, with high temperature and pressure promoting sintering densification but also resulting in increased grain size. The ceramics achieved high density and fine grain size when sintered at 1800 degrees C for 10 minutes under 80 MPa, with Vickers hardness, Young's modulus, and fracture toughness values of 15.60 GPa, 512.66 GPa, and 3.59 MPa∙m1/2, respectively. The dominant densification mechanisms were diffusion and grain boundary sliding, with an apparent activation energy of 252.94 kJ/mol.