On the influence of carbide coating on the thermal conductivity and flexural strength of X (X = SiC, TiC) coated graphite/Al composites

The interface between graphite flakes (GF) and Al in composites significantly affects the interfacial thermal diffusion and mechanical property characteristics. Silicon carbide and titanium carbide coating have been introduced to the surface of GFs to investigate the thermal conductivity and flexural strength of GF/Al composites. Microstructural analysis demonstrates that the coating thickness of the SiC/TiC are about 268 nm and 329 nm, respectively. The experimental results show that (i) SiC coating on the GF and the reduction of particle size increase the thermal conductivity and flexural strength. Compared with the raw GF/Al composites, the thermal conductivity of the SiC coated GF/Al composites increases from 610 to 633 W (m K)(-1) when the volume fraction of GF reaches 70 vol% and the particle size of Al is about 20 mm. And the thermal conductivity of 70 vol% SiC GF/Al composites approaches 704 W (m K)(-1), when the size of Al powder decreases to 1 mm; (ii) TiC coating on the GF greatly increases the flexural strength of the composites, but decreases the thermal conductivity sharply. The bending strength of TiC-coated GF/Al composites approaches 103 MPa when the particle size of Al is about 1 mm, when the volume fraction of GF is 50 vol%. Additionally, the experimentally determined thermal conductivities are compared with the theoretically calculated values in this study.