Characterization of Thermal Conductivity of Carbon Fibers at Temperatures as Low as 10 K

Due to their excellent thermal structural properties, carbon fibers have been extensively applied in the fields of mechanical and aerospace engineering. Many studies have been conducted at room temperature or higher, yet the literature gives very few data on the measurement of thermophysical properties at very low temperatures. The thermal diffusivity of two kinds of carbon fibers was measured by the transient electrothermal technique at very low temperatures (down to 10 K) in the work, the ρCp followed the Debye T3 law dependence quite accurately in agreement with theoretical investigations at very low temperatures(< 10 K). The thermal diffusivity of carbon fiber almost increases linearly with decreasing temperature, but when the temperature drops down below 90 K, the thermal diffusivity rapidly decreases. The thermal expansion mismatch between the different materials present in carbon fibers may influence the change of thermal diffusivity. The relationship between the impurity concentration and the thermal transport of the carbon fibers is discussed.