Determination of microstructure and mechanical properties of graphene reinforced Al2O3-Ti(C, N) ceramic composites

Abstract

Al2O3-Ti(C, N) ceramic composites reinforced with graphene nano-platelets (GNPs) were fabricated via hot-pressing sintering (HP). The effects of GNPs content on the microstructure, mechanical properties, thermal conductivity and reinforcing mechanisms of the composites were investigated. To make GNPs dispersed homogeneously in ceramic matrix, N-Methyl-2-pyrrolidone (NMP) was used as dispersing media and alcohol solution of polyvinyl pyrrolidone was used as reference. Results show NMP is an effective dispersing media for powder mixing. The mechanical properties of Al2O3-Ti(C, N) composites are improved with the addition of GNPs, and when GNPs content is 0.4 wt%, significant improvements in fracture toughness (40.13%) and flexural strength (40.78%) are achieved in comparison with those of specimens without GNPs. However, there is no obvious effect of GNPs content change on the thermal conductivity of the composites when GNPs content is below 0.8 wt%. Many reinforcing mechanisms induced by GNPs are related to the interfacial bonding strength between GNPs and ceramic matrix. Pull-out of GNPs, crack deflection and branching are caused by weak interfaces between GNPs and matrix while crack bridging and alteration of fracture mode are caused by strong interfaces. Furthermore, interleaving distribution of weak and strong bonding interfaces between GNPs and matrix is essential for the reinforcement of ceramic composites.