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

SiCw-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 SiCw-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. SiCw-SiC foams have a density of 0.11 <= p <= 0.12 g/cm(3), porosity >= 96% and a thermal conductivity at room temperature between 0.040 and 0.075 W/m.K. Thermal conductivity of the SiCw-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.