Effects of graphene content on the microstructure and properties of copper matrix composites

Copper matrix composites reinforced with graphene nanoplatelets (GNPs) were prepared via molecularlevel mixing process and spark plasma sintering process. The impacts of graphene content on microstructure, mechanical performance, thermal diffusivity, electrical conductivity and tribological properties of the composites were investigated. For microstructure, GNPs distributed randomly in composites with low graphene concentration (no more than 0.8 vol.%), but aligned in the direction perpendicular to the consolidation force when graphene concentration was above 2.0 vol.%. The mechanical performance of copper was strengthened evidently by the graphene addition. However, the strengthen effects were firstly enhanced and then deteriorated by increasing graphene content. Thermal diffusivity showed a constant decrease with the increase of graphene content. Anisotropy thermal performance was obtained by composites with graphene alignment. Furthermore, graphene addition showed little negative impact on electrical conductivity but dramatically improved tribological performance. (C) 2015 Elsevier Ltd. All rights reserved.