A Novel Approach to Enhance the Mechanical Strength and Electrical and Thermal Conductivity of Cu-GNP Nanocomposites

Copper/graphene nanoplatelet (GNP) nanocomposites were produced by a wet mixing method followed by a classical powder metallurgy technique. A qualitative evaluation of the structure of graphene after mixing indicated that wet mixing is an appropriate dispersion method. Thereafter, the effects of two post-processing techniques such as repressing–annealing and hot isostatic pressing (HIP) on density, interfacial bonding, hardness, and thermal and electrical conductivity of the nanocomposites were analyzed. Density evaluations showed that the relative density of specimens increased after the post-processing steps so that after HIPing almost full densification was achieved. The Vickers hardness of specimens increased considerably after the post-processing techniques. The thermal conductivity of pure copper was very low in the case of the as-sintered samples containing 2 to 3 pct porosity and increased considerably to a maximum value in the case of HIPed samples which contained only 0.1 to 0.2 pct porosity. Electrical conductivity measurements showed that by increasing the graphene content electrical conductivity decreased.