Preparation, microstructure, and compressive strength of carbon foams derived from sucrose and kaolinite

Carbon foams were successfully fabricated from sucrose and kaolinite clay by thermo-foaming method using aluminum nitrate as the blowing agent. The phases, pore structure, and compressive strength were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and mechanical test, respectively. The foams had porous structure with spherical open cells of size in the range of 400–1000 µm, dense struts, and interconnected voids of size in the range of 100–600 µm. Both smooth and coarse types of voids are observed. Mullite and cristobalite, products of the clay mineral, are concentrated more on the strut and cell walls. The ultimate compressive strength evolution is found to be in correlation with the amount of voids and the microcracking in the carbon foams.