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

Abstract

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.