High-Strength ZrC Ceramics Doped with Aluminum

High‐strength ZrC ceramics with relative density above 98% were prepared by reactive hot pressing of ZrC and Al at 1900°C. The reaction between ZrC and Al resulted in the formation of ZrC1−x, Zr3Al3C5 and Zr–Al compound such as AlZr3 and Al–C–Zr. The intermediate product AlZr3 below 1600°C and remained Al–C–Zr phase could form liquid phase and promoted the first stage of densification process. The improvement in densification behavior at higher temperatures (1800°C–1900°C) could be attributed to the formation of nonstoichiometric ZrC1−x. Adding 5 wt% and 7.5 wt% Al to ZrC, the formed ZrC0.85–Zr3Al3C5 and ZrC0.80–Zr3Al3C5 based ceramics had 3‐point bending strength as high as 757 ± 79 MPa and 967 ± 50 MPa, respectively, with hardness and fracture toughness being 16.2–18.3 GPa and 3.3–3.5 MPa m1/2, respectively.