Graphene Nanosheets\nalong Grain Boundaries in a Zirconia-Toughened\nAlumina Ceramic Significantly Improve Fracture Strength

Bioinspired interfacial structures in materials, such\nas nacre-inspired\nmasonry structures and bionic mechanical interlocking structures,\ncan produce unique effects that enable unprecedented material mechanical\nproperties. However, the smooth interface in ceramic materials is\nknown to elicit weakening effects on mechanical properties, easily\ncausing catastrophic damage in industrial production. Here, inspired\nby the suture structure of fish, zirconia-toughed alumina (ZTA) is\nfabricated with a bioinspired suture structure interface by introducing\na graphene nanosheet (GNS) through tailoring the interfacial atomic\ndiffusive rate on a ZTA composite, and its effect on fracture strength\nis measured. The results show that the flexural strength of ZTA modified\nby 0.14% GNS is 865.4 MPa, which is 60.2% higher than that of ZTA\nwithout GNS modification. Subsequently, the local grain boundary slip\nresistance on the suture interface is calculated using finite element\nsimulation, which reveals that the suture interface of the Al<sub>2</sub>O<sub>3</sub> matrix had higher resistance values than the\nsmooth interface under applied load, which could improve the hardness,\nflexural strength, and fracture toughness. This unique suture interface\nintensifies the interface strength and essentially improves the force\ntransmission. This work provides guidance for bionic optimization\nof the grain boundary structure of structural ceramics and a new idea\nfor the structural design of high-strength and -toughness ceramics.