Thermal, mechanical and self-destruction properties of aluminum reinforced carbon foam

Abstract

Carbon foam has been developed by templating method with phenolic resin and coal tar pitch as matrix precursor and polyurethane foam as a sacrificial template. For improving thermal and mechanical properties, aluminum (Al) powder with 2–8 wt% was added into the impregnation mixture. Carbonization at 1273 K in inert environment under the cover of coke breeze produced Al4C3 in situ and AlN by substitution reaction. Various thermal and mechanical tests showed a density of 0.50–0.58 g/cm3, open porosity of 64–68 %, thermal conductivity of 0.043–0.385 W/mK and a compressive strength of 17–32 MPa for the samples containing 0–6 wt% Al. Scanning electron microscope was used to evaluate the pore morphology, distribution of Al in the porous network and an approximate pore size distribution which came out to be in the range of 2–200 μm. X-ray mapping showed a homogeneous dispersion of Al with some agglomerates into the ball shape. Carbon foam with 8 wt% Al showed self-destruction in 14 days after 15 days of manufacturing. The destruction started from core and proceeded towards outer surface resulting in a core–shell effect. X-ray diffraction analysis confirmed the destruction due to the formation of Al4C3 and reaction with atmospheric moisture forming Al(OH)3. This property can be further explored to be applied in the field of composite tooling for advanced carbon fiber reinforced composites. The tool will lose strength after certain time, facilitating in easy removal from the complex shape composites.