Graphene Nanosheets along Grain Boundaries in a Zirconia-Toughened Alumina Ceramic Significantly Improve Fracture Strength

Bioinspired interfacial structures in materials, such as nacre-inspired masonry structures and bionic mechanical interlocking structures, can produce unique effects that enable unprecedented material mechanical properties. However, the smooth interface in ceramic materials is known to elicit weakening effects on mechanical properties, easily causing catastrophic damage in industrial production. Here, inspired by the suture structure of fish, zirconia-toughed alumina (ZTA) is fabricated with a bioinspired suture structure interface by introducing a graphene nanosheet (GNS) through tailoring the interfacial atomic diffusive rate on a ZTA composite, and its effect on fracture strength is measured. The results show that the flexural strength of ZTA modified by 0.14% GNS is 865.4 MPa, which is 60.2% higher than that of ZTA without GNS modification. Subsequently, the local grain boundary slip resistance on the suture interface is calculated using finite element simulation, which reveals that the suture interface of the Al2O3 matrix had higher resistance values than the smooth interface under applied load, which could improve the hardness, flexural strength, and fracture toughness. This unique suture interface intensifies the interface strength and essentially improves the force transmission. This work provides guidance for bionic optimization of the grain boundary structure of structural ceramics and a new idea for the structural design of high-strength and -toughness ceramics.