Thermal properties of in situ grown graphene reinforced copper matrix laminated composites

Copper micro-flakes were encapsulated with in situ catalytically grown graphene and then assembled into graphene/Cu (Gr/Cu) laminated composite under pressure at high temperature. The thermal conductivity (TC) and coefficient of thermal expansion (CTE) of the composites were investigated systematically. Although in situ catalytic growth graphene can avoid structural damage in a usual mechanical alloying process and is beneficial for improving interfacial bonding, the Gr/Cu laminated composites show decreased TC in both directions compared to the pure Cu matrix prepared by the same process. The composites exhibit anisotropic thermal properties owing to their laminated architecture and two-dimensional character of graphene. Given a volume fraction of graphene, the cross-plane TC of the Gr/Cu composite is lower than the in-plane TC because of more multilayer-graphene/copper interfaces and low cross-plane TC of graphene. Although the fraction of graphene is only 0.75 vol%, the Gr/Cu composite has a significantly lower cross-plane CTE than the pure Cu matrix in a wide temperature range. (C) 2018 Elsevier B.V. All rights reserved.