Thermal conductivity of graphite flakes–SiC particles/metal composites

A new family of high thermal conductivity composites, produced through infiltration of a metallic alloy into preforms of mixtures of graphite flakes and either ceramic or carbon materials (in the form of particles or short fibers), has been recently developed. Composites microstructure roughly consists of alternating layers of flakes and metal-particles composite. The present work focuses on graphite flakes–SiC particles/Al–12 wt%Si composites. The effects that the relative amounts of the components, as well as the average diameter of SiC particles (varied over the range 13–170 μm), have on the thermal conductivity are investigated. The experimental results are analyzed by means of two model microstructures: (i) alternating layers of flakes and metal-particle composite, and, (ii) oriented discs (graphite flakes) randomly distributed in a metal-particle composite matrix. Fitting experimental data by means of these model microstructures leads to reasonable values of the thermal conductivity of graphite flakes along the transversal and longitudinal directions.