Thermal conductivity and mechanical properties of a flake graphite/Cu composite with a silicon nano-layer on a graphite surface

Abstract

The interface between graphite flakes (G_f) and Cu in composites significantly affects the interfacial thermal diffusion and mechanical property characteristics. Silicon (Si) coating has been introduced to the surface of the G_f to investigate the thermal conductivity and flexural strength of G_f/Cu composites. Microstructural analysis demonstrates that (i) the high thermal conductivity of G_f/Cu composites is attributed to the homogeneous dispersion and well-controlled alignment of G_f in the composite matrix and (ii) silicon coating on the G_f slightly decreases the thermal conductivity of the composites, but greatly improves the bending strength. Compared with the raw G_f/Cu composites, the thermal conductivity of the Si-coated G_f/Cu composites along the plane parallel to the graphite laminate decreases from 676 to 610 W (m⁻¹ K⁻¹) when the volume fraction of G_f reaches 70 vol%. The bending strength of Si-coated graphite/Cu composites is significantly enhanced and the maximum bending strength is 110 MPa when the volume fraction of graphite is 40%. Additionally, the experimentally determined thermal conductivity is compared with the theoretically calculated value in this study.