Crack tolerant TaC–SiC ceramics prepared by spark plasma sintering

To achieve the densification of tough tantalum carbide ceramics at low sintering temperature, we reported a preparation of TaC ceramics by spark plasma sintering with SiC as the sintering aid and graphene platelet (GPL) as the reinforcement. The effects of GPL contents on the densification, grain growth and mechanical properties of the TaC–SiC/GPL composites were evaluated. Due to the surface reactions between SiC and TaC particles, relative density of the composite increased to 99.3% at GPL content of 1.0 wt%. The GPLs wrapped around the grains and acted as barriers for mass diffusion, therefore inhibiting grain growth. The flexural strength of the composite increased at first and reached maximum value of 570 MPa at the GPL content of 1.0 wt%; the fracture toughness reached the peak value of 5.8 MPa m1/2 at the GPL content of 1.5 wt%. Bending, bridging and pullout of GPLs were considered as the main toughening mechanisms. Thus, this work provides a new guide for the fabrication of TaC ceramics with high density and high fracture strength.