Enhanced through-plane thermal conductivity and mechanical properties of vertically aligned graphene nanoplatelet@graphite flakes reinforced aluminum composites

Graphite flakes reinforced aluminum matrix (Gr/Al) composites with high thermal conductivity , low thermal expansion and low bulk density have been widely studied. However, the application of Gr/Al composites has been limited due to the low through-plane thermal conductivity as well as poor mechanical properties . In this work, the vertically aligned graphene nanoplatelet (GNP) was initially grown on the surfaces of Gr flakes (Gr(GNP)) by chemical vapor deposition (CVD), and then the Gr(GNP)/Al composites were consolidated by vacuum hot-pressing technique. By this way, the through-plane thermal conductivity and mechanical strength are jointly enhanced. With GNP content increases up to 3.3 vol%, the through-plane thermal conductivity can be improved by 96.8% due to the establishment of through-plane heat-conducting channels. Meanwhile, because of the strengthening effect of GNP on the interface region, the flexural strength can be strongly enhanced by 122%. However, with the further increase of GNP content, the through-plane thermal conductivity and flexural strength begin to decline due to the agglomeration of GNP, but are still higher than that of Gr/Al composite.