Carbon foam derived from various precursors

Abstract

A series of carbon foams was developed by using low-cost precursors, such as coal, coal tar pitch and petroleum pitch. The properties of the resultant carbon foams cover a wide range, e.g., bulk density, 0.32-0.67 g/cm3, compressive strength, 2.5-18.7 MPa, isotropic and anisotropic microstructure, etc. The investigation of foaming mechanism and the relationship between properties and structure indicate that the fluidity and dilatation of the foaming precursors significantly affect the foaming performance and foam structure. Raw coal samples were foamed directly without pretreatment in this work. However, for the pitch based foaming precursor, a thermal pretreatment is necessary to adjust its thermoplastic properties to meet the foaming requirement. The mechanical strength of carbon foam is found to be related to not only the foam cell structure, but also the fluidity and anisotropic domain size of the foaming precursors. In addition, the micro and mesopore structure in carbon foam matrix was investigated by gas adsorption and it was found that it also affects the strength of carbon foam and is related to the fluidity of foaming precursor. © 2005 Elsevier Ltd. All rights reserved.