Nano/microstructures and mechanical properties of Al2O3-WC-TiC ceramic composites incorporating graphene with different sizes

Graphene additives with different sizes were employed to strengthen and toughen Al2O3-WC-TiC ceramic composites. The effect of graphene sizes on interfacial characteristics, microstructures and mechanical properties was investigated. The results indicated that the interfacial chemistry reaction products and sizes of the products were subject to graphene sizes. With the increase of graphene thickness, the interfacial reaction products between graphene and Al2O3 changed from Al4O4C to Al4C3 and the sizes of products were increased. Based on first-principles calculation results, it has been found that Al4O4C and Al4C3 interfacial phases contributed to the formation of the strong-weak staggered interfaces in ceramic composites. Graphene with low thickness and large lateral size was more beneficial to improve mechanical properties of ceramic composites. Especially, the flexural strength and fracture toughness of the composite incorporating single layer graphene were increased by 67.59% and 54.10%, respectively, compared to the composite without graphene. The strong-weak staggered interfaces induced by graphene were responsible for the improved flexural strength and fracture toughness.