Formation of tough interlocking microstructure in ZrB2-SiC-based ultrahigh-temperature ceramics by pressureless sintering

A self-reinforced ultrahigh-temperature ceramic (UHTC) with elongated ZrB2 grains has been successfully densified by pressureless sintering using commercially available ZrB2, SiC, and WC powders as raw materials. Benefiting from the unique interlocking microstructure, this material had improved strength (518 +/- 10 MPa) and higher fracture toughness (6.5 +/- 0.2 MPa m(1/2)) compared to ZrB2-SiC ceramics prepared by pressureless sintering. This work provides a new route for tailoring the microstructure and mechanical properties of UHTCs.