Preparation of graphite flakes/Al with preferred orientation and high thermal conductivity by squeeze casting

Abstract

High thermal conductive graphite flakes/Al composites were prepared by optimized squeeze casting technique with higher molten temperature and lower infiltration pressure. The characterization and thermal conductivity (TC) of graphite flakes/Al composites were investigated. The graphite flakes/Al composite prepared from 70 vol. % natural graphite has a high TC as high as 714 W/m K, as well as a high thermal diffusivity of 388 mm2/s in the plane parallel to the graphite layers. However, the compressive and flexural strengths in direction perpendicular to the graphite layers are limited to 17.6 and 16.9 MPa, respectively. Microstructural analysis demonstrates that the graphite flakes/Al composites have a typical structural anisotropy derived from the three-dimensional layered arrangement of the highly oriented graphite flakes. Meanwhile transmission electron microscope observations further illustrate that the formation of a tightly-adhered amorphous layer interface between graphite flakes and Al matrix without Al4C3 reaction product, which is contributed to the excellent thermal conductive of graphite flakes/Al composites.