Mxene-toughened Al2O3 ceramic at high temperature

The process of toughening brittle ceramics is challenging but important for broadening their range of applications. Extensive studies on toughening brittle alumina (Al2O3) ceramics at room temperature have been conducted; however, significantly increasing their toughness at high temperatures remains a challenge. Here, we propose the use of two-dimensional Ti3C2Tx MXene ceramics with high thermal stability to effectively toughen Al2O3 ceramics at high temperatures via a nacre-like structure strategy. The fracture toughness (KJc) of the as-prepared MXene/Al2O3 nanocomposite at 1000 °C is 6.02 MPa m1/2, 2.4 times that of pure Al2O3 (2.51 MPa m1/2). Moreover, it maintains relatively high strength at 1000 °C (∼193 MPa). The toughening mechanisms - crack deflection, bifurcation and bridging effects - are obtained via in situ observation of crack propagation and finite element simulation. Our novel strategy provides a universal solution to improve the toughness of brittle ceramics at high temperatures and in some special environments.