Densification behavior and mechanical properties of spark plasma-sintered ZrC-TiC and ZrC-TiC-CNT composites

Titanium carbide (TiC) and carbon nanotubes (CNTs) were introduced into zirconium carbide (ZrC) ceramics to improve the fracture toughness. ZrC-TiC and ZrC-TiC-CNT composites containing 0-30 vol.% TiC and 0.25-1 mass% CNT were prepared by spark plasma sintering at temperatures of 1750-1850 C for 300 s under a pressure of 40 MPa. Densification behavior, microstructure, and mechanical properties of the ZrC-based composites were investigated. Fully dense ZrC-TiC and ZrC-TiC-CNT composites with a relative density of more than 98 % were obtained. Vickers hardness of ZrC-based composites increased with increasing TiC content and the highest hardness was achieved with the addition of 20 vol.% TiC. Addition of CNTs up to 0.5 wt% significantly increased the fracture toughness of ZrC-based composites, whereas the addition of TiC did not have this effect.