Preparation of silicon carbide reticulated porous ceramics

Commercial polyurethane sponges with cell size of ≈11 pores per inch were chosen to produce SiC-based reticulated porous ceramic (RPC) by the replication process. The dispersion of mixed powders (SiC, Al 2O 3, bentonite) in aqueous media using silica sol as a binder was studied by zeta potential and viscosity/rheological measurements. The pH value of the optimum dispersion was found to be around pH 10 for the mixtures. The optimum condition of the slurry suitable for impregnating the polymeric sponge was obtained. Effects of coating parameters including the separation between the rollers and the number of passes on the coating quality and macrostructure of RPCs were studied in detail. Flexural strength data of the sintered bodies were compared to a theoretical model. A statistical evaluation was carried out on the flexural strength data of the sintered bodies using Weibull statistics.