Low temperature consolidation for fine-grained zirconium carbide from nanoparticles with ZrH2 as sintering additive

Zirconium carbide (ZrC0.84O0.13) nanopowders were consolidated using plasma activated sintering with 0-8 wt% ZrH2 as the sintering additive to improve the sinterability. Compared with pure ZrC sintering, ZrH2 additive led to the higher sintering kinetics and lower sintering temperature. This improvement was attributed to the increased carbon-vacancy concentration in the non-stoichiometric ZrC in the presence of ZrH2 additive during the sintering process. Fully dense and fine-grained ZrC ceramics (1.3 ± 0.2 μm) were achieved at 1650 °C with 6 wt.% ZrH2. The final product exhibited the Vicker's hardness of 21.2 ± 1.0 GPa and fracture toughness of 2.2 ± 0.3 MPa m1/2.