Architecting micron SiC particles on diamond surface to improve thermal conductivity and stability of Al/diamond composites

In this paper, a new method to synthesize micron silicon carbide (SiC) particles on the diamond surface at low temperature was proposed, namely, the micron SiC particles had been synthesized by aluminum-silicon (Al-Si) mixed powders and vacuum annealing technology. Continuity and formation mechanism of the SiC particles were studied. The continuity of the SiC particles is affected by annealing temperature and the mass fraction of silicon (Si) in Al-Si mixed powders. When the mass fraction of Si in Al-Si powders is 70 wt.% and the annealing temperature is 800°C, SiC particles with a continuous structure can be synthesized. Aluminum carbide (Al4C3) as the indispensable intermediate phase plays a crucial role in promoting the formation of SiC particles at low temperature. The Al/diamond composite with high thermal conductivity of 711 W·m−1·K−1 was obtained by introducing SiC particles with a continuous structure. Meantime, the continuous SiC layer effectively inhibited the formation of Al4C3 at the interface of the composite, and only 0.5 wt.% of Al4C3 was detected by gas chromatography. This study provides a novel practical way for surface coating engineering on diamond particles, which can be used to improve thermal conductivity and inhibit the interfacial Al4C3 of Al/diamond composites.