Thermal Characterization of Silicon Carbide Nanowire Films

This paper reports on thermal characterization of SiC nanowire films on alumina substrate. The SiC nanowires films were synthesized via carbothermal reduction by thermal evaporation of silica and graphite powders using a high temperature alumina tube furnace. Structural characterization showed that nanowires have a core-shell structure, with a core of single crystal SiC of ∼50 nm in diameter and an amorphous shell of silicon oxide of ∼10 nm in thickness. Prior thermal measurements as-deposited SiC nanowires were compacted into more dense films via capillary coalescence. The effective thermal conductivity in the direction perpendicular to the film was determined employing a steady-state experimental method in conjunction with one-dimensional heat transfer modeling. Preliminary results suggest that these films have a very low thermal conductivity, in the range of 0.1W/mK. The low thermal conductivity may be due to intrinsic structure of the nanowire film such as porosity and large number of interfaces between the SiC nanowire core and its outer oxide layer as well as thermal contact resistance at nanowires junctions.