Nano/microstructures and mechanical properties of Al2O3-TiC ceramic composites reinforced with Al2O3@RGO nanohybrids

A simple self-assembly method was applied for the successful synthesis of reduced graphene oxide-encapsulated alumina (Al2O3@RGO) nanohybrids with core-shell structures which were then added as nanofiller into a matrix of Al2O3-TiC to fabricate corresponding ceramic composites. Microstructural analysis revealed that RGO sheets were homogeneously dispersed in the matrix and bonded to grains to form a 3D RGO network. The formed unique structure forced RGO sheets to closely bond and strongly attach to matrix grains, effectively increasing load transfer efficiency and contact surface area between matrix and RGO sheets. Analysis of interface charac-teristics revealed that the interfacial phase Al2OC was generated by a localized carbothermic reduction process. Based on first-principles calculations, Al2OC interfacial phase was found to contribute to the generation of weak and strong hybrid interfaces in composites. The weak and strong hybrid interfaces could not only effectively promote the transfer of loads from the matrix to RGO sheets but also induce conventional toughening mecha-nisms. In summary, addition of Al2O3@RGO nanohybrids effectively improved the dispersion level of RGO in ceramic as well as interfacial bonding strength between these sheets and matrix, thereby improving overall mechanical characteristics of Al2O3-TiC ceramic composites.