Abstract
Highly oriented graphite-based composites have attracted great attention because of their high thermal conductivity (TC), but the low mechanical properties caused by the inhomogeneous distribution and discontinuity of reinforcements restrict the wide applications. Herein, continuous SiC ceramic skeleton reinforced highly oriented graphite flake (SiC/GF) composites were successfully prepared by combining vacuum filtration and spark plasma sintering. The effect of SiC concentration on the microstructure, flexural strength, and thermophysical properties of the composites was investigated. The GF grains in the composites exhibited high orientation with a Lotgering factor of > 88% when the SiC concentration was ⩽ 30 wt%, and the SiC skeleton became continuous with the SiC concentration reaching 20 wt%. The formation of continuous SiC skeleton improved the flexural strength of the composites effectively while keeping the TC in a high level. Especially, the composites with 30 wt% SiC exhibited the flexural strength up to 105 MPa, and the specific TC reaching 0.118 W·m2·K−1·kg·1. The composites with excellent flexural strength and thermophysical properties showed significant promise for thermal management applications.
Highlights
Nowadays, the intelligent electronic devices have been developed towards high power density and miniaturization direction, which arouses urgent requirement for the thermal management materials (TMMs) with excellent performance [1,2,3,4]
A small number of pores can be observed in the skeleton reinforced highly oriented graphite flake (SiC/graphite flake (GF)) composites when the SiC concentration is lower than 50 wt%
As the concentration of SiC increases, the number of pores gradually reduces and the pores disappear in the SiC50/GF composite, which demonstrates that the increase of SiC concentration is beneficial to the densification of the composites
Summary
The intelligent electronic devices have been developed towards high power density and miniaturization direction, which arouses urgent requirement for the thermal management materials (TMMs) with excellent performance [1,2,3,4]. Its CTE of about 4 × 10−6 K−1 [26,27], much lower than that of GF in through-plane direction (28 × 10−6 K−1), can introduce tensile stress in GF along this direction and reduce the CTE of the composites [17] This improves the reliability of SiC reinforced GF composites as TMMs for electronic devices after repetitive thermal cycles. Preparing 3D continuous SiC skeleton reinforced highly oriented GF composites is an appealing approach to synergistically optimize the mechanical and thermophysical properties of highly oriented graphite-based composites. Thereby, the 3D continuous SiC skeleton can be successfully introduced in the highly oriented GF matrix, and the anisotropic SiC/GF composites with high strength and specific TC in plane direction were achieved. The effect of SiC weight fraction on the microstructure, flexural strength, and thermophysical properties of the composites were systematically investigated
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