摘要

Core-shell-structured nanocapsules with a copper core encapsulated in a carbon shell (Cu-C) were synthesized by a direct-current arc-discharge method. Morphological and microstructural characterization showed that the Cu-C consisted of a nanosized Cu core and carbon shell, with the carbon shells containing 6 to 15 ordered graphitic layers and amorphous carbon that effectively shield the metallic Cu core from oxidation. A thermally conductive composite was successfully fabricated using a silica gel matrix incorporated with Cu-C filler. The Cu-C nanoparticles were homogeneously dispersed in the silica gel. The effects of Cu-C on the thermal conductivity, electrical resistivity, and coefficient of thermal expansion (CTE) of the composite were investigated. For composites with 6.16 vol.%, 11.04 vol.%, 16.70 vol.%, and 23.34 vol.% Cu-C content, the thermal conductivity at 50A degrees C was 0.32 W/(m K) to 0.77 W/(m K), the electrical resistivity was 1.98 x 10(9), 3.48 x 10(7), 302, and 1 Omega m, respectively, while the CTE at 200A degrees C was 3.79 x 10(-4) K-1 to 3.44 x 10(-4) K-1. The results reveal that the ordered graphitic shells in the Cu-C increased both the thermal and electrical conduction, but decreased the CTE by preventing the Cu cores from expanding.