Enhancing the mechanical and thermophysical properties of highly oriented graphite flake composites by formation of a uniform three dimensional tungsten carbide skeleton reinforcement

Tungsten carbide (WC) reinforced highly oriented graphite flake composites were obtained using a combined process of surface-coating and spark plasma sintering techniques. Uniform and continuous three-dimensional WC skeleton was formed in the samples with WC concentration higher than 7 vol%, rendering the resulting dense composites light, mechanical strong, high thermal conductive and with low thermal expansion. The skeleton architecture played a role of thermal expansion constraint which remarkably reduced the thermal expansion from 28 × 10⁻⁶ K⁻¹ for highly oriented graphite matrix to ~5 × 10⁻⁶ K⁻¹ for the composite with 26 vol% WC in the direction parallel to the sintering pressure. Concurrently, the composite with 26 vol% WC exhibited bending strength up to ~95 MPa, thermal conductivity up to ~381 W·m⁻¹·K⁻¹ in direction perpendicular to the sintering pressure. The created highly oriented graphite-based composites with uniform 3D ceramic reinforcement are expected to be applied in thermal management of current demanding situation.