Preparation and thermal insulation analysis of SiC_w-SiC foam with hollow skeletons via carbon foam template CVI method

SiC_w-SiC foams with hollow skeleton were synthesized by a simple procedure that consisted of the chemical vapor infiltration (CVI) and oxidation process. Flexible carbon foam was employed as CVI template. A typical structure of SiC_w-SiC foams consisting of SiC supporter with hollow skeleton structure accompanying numerous crooked SiC whiskers was obtained after burning out carbon skeleton of the carbon foam during oxidation process. SiC_w-SiC foams have a density of 0.11 ≤ ρ ≤ 0.12 g/cm³, porosity ≥ 96% and a thermal conductivity at room temperature between 0.040 and 0.075 W/m·K. Thermal conductivity of the SiC_w-SiC foams moderately increased with elevation of temperature, indicating that these foams with larger amount of whiskers exhibit excellent thermal insulation property at elevated temperature.