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 degrees 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 degrees 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 degrees C-1900 degrees C) could be attributed to the formation of nonstoichiometric ZrC1-x. Adding 5wt% and 7.5wt% Al to ZrC, the formed ZrC0.85-Zr3Al3C5 and ZrC0.80-Zr3Al3C5 based ceramics had 3-point bending strength as high as 757 +/- 79MPa and 967 +/- 50MPa, respectively, with hardness and fracture toughness being 16.2-18.3GPa and 3.3-3.5MPam(1/2), respectively.