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

摘要

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.