Cordierite-based porous ceramic samples were successfully prepared using a mixture composed of waste silica fumes, bauxite and talc via a polymeric sponge replica technique. Firstly, the optimum sintering conditions (in terms of sintering temperature and time) for acquiring as much of the cordierite phase with the absence of undesirable ones were determined for a dense mixture compact. The results revealed that a sintering temperature of 1350 oC and a sintering time of 2 h were the most appropriate conditions during cordierite synthesis. Secondly, the key role for the successful fabrication of a porous ceramic body via replica method is to prepare a well-dispersed suspension from the mixture of raw materials. Here the optimum conditions for preparing a well-dispersed suspension in terms of type and concentration of additives as well as suspension pH were evaluated. The using of 0.2% sodium silicate and a suspension pH of 8 were found to be the most favorable conditions for obtaining a well-dispersed suspension. Thirdly, in order to prepare porous cordierite, polyurethane foam was impregnated with a well-dispersed suspension and sintered at the optimum conditions conducted for a dense cordierite sample. The porous cordierite produced was found to possess 46.4% total porosity. The porosity was comprised of large and small interconnected pore surrounded by a web of ceramic. This structure is suitable for applications in filtering purposes.

Keywords: Silica fumes, Cordierite, Porous structure, Rheology, Well-dispersed suspension, Replica method.