Lateral size effect of reduced graphene oxide on properties of copper matrix composites

Graphene/copper composite using graphene oxide sheets with three kinds of lateral sizes (~0.92 μm, ~5.49 μm and ~13.73 μm) were prepared via molecular level mixing method and spark plasma sintering process. The lateral size effects of graphene on the structure, mechanical performance, thermal and electrical conductivities of the composites were investigated while the volume fraction of graphene remained 2.5 vol%. For microstructure, small-sized graphene sheets (denoted as SRGO) tend to distribute randomly in the composites while middle-sized (denoted as MRGO) and large-sized graphene sheets (denoted as LRGO) are prone to form the carbon-rich aggregate with micro-layered structure. MRGO/Cu composite has the highest tensile yield strength (663 MPa) while SRGO/Cu composite exhibits the most excellent thermal and electrical conductivities (334 W/(m × K), 82 %IACS) among the three composites. This work provides a better understanding the formation mechanism of hierarchical layered graphene/Cu composite and can further promote the development of architectural design of graphene based composites.