Anisotropy of mesophase pitch-derived carbon foams

Carbon foams with uniform pore size were produced from mesophase pitch in a high-pressure chamber. The morphologies, crystal structure and mechanical properties of as-grown carbon foams, carbonized and graphitic foams were investigated. The microwave absorbing properties of carbon foam sandwich composites at 2-18 GHz were also examined. It was found that the extension of pores in the xz-plane direction (parallel to the direction of gravitational force) was larger than that in the xy-plane direction (perpendicular to the direction of gravitational force). The compressive strength and modulus of resultant foams in the xz-plane direction were higher than those in the xz-plane direction. Further, the reflection loss of the sandwich composites composed of xy-plane carbon foam slabs was lower than that of xz-plane composites. The results of this work showed that carbon foam was a kind of anisotropic material. (c) 2006 Elsevier Ltd. All rights reserved.