Shengjie Yu

A study of thermal insulation properties and microstructure of ultra-light 3D-carbon foam via direct carbonization of polymer foam

This paper describes the preparation of ultralight flexible carbon foam (FCF) by direct carbonization of commercial melamine foam (MF). The effect of carbonization temperature on microstructure characteristics and thermal properties in FCF were evaluated. The thermal conductivity of the samples at ambient temperature was measured using the heat flow tester and the thermal conductivity of the samples at various temperatures was measured using water flow plate method. The pore distribution and microstructure morphology of the MF sample and FCF samples were also measured by mercury intrusion porosimetry and SEM imaging, respectively. The results show that the 3D network architecture and the triangle fiber shape of the MF precursor were inherited by the resulting FCF samples despite of a great reduction in volume. The average pore diameter of FCF samples reaches a lowest value for carbonization temperature of 850 °C. The thermal conductivity of FCF samples is considered to be affected by the porosity characteristic of FCF samples. The higher pore diameter of FCF samples, the greater its thermal conductivity.

Effect of SiC Whiskers on the Microstructure and Thermal Conductivity of Carbon Foam

This paper describes the modification of ultralight flexible carbon foam by chemical vapor deposition (CVD) of silicon carbide whiskers (SiCw). The effect of SiC whiskers on the microstructure and the thermal conductivity of carbon foam were investigated by scanning electron microscopy (SEM) and laser flash diffusivity method in a Netzsch LFA427. The results show that the macro-pores (~30 μm) of the carbon foam were divided by the random distribution of SiC whiskers. The diameter of SiC whiskers decreased with decreasing catalyst concentration which resulted in the improved microstructure with a smaller pore diameter (4~6 μm) and a more homogeneous distribution of the pores. The carbon foam reinforced by SiCw exhibits better insulation performance than the pristine carbon foam when the temperature exceeds 200°C.