Producing Large Complex-Shaped Ceramic Particle Stabilized Foams

Highly porous ceramic foams can be produced by combining particle stabilized foams and gelcasting concepts. Sulfonate-type surfactants are selected to weakly hydrophobize the alumina surface and stabilize air bubbles in suspensions containing gelcasting additives, polyvinyl alcohol (PVA), and 2,5-dimethoxy-2,5-dihydrofurane (DHF). The aim of this work was to prepare large complex-shaped ceramic foam objects with homogeneous microstructure and high porosity. A key to avoiding drying cracks is to strengthen the wet green body via gelcasting. The influence of the amount of gelcasting additives on the mechanical strength of the ceramic foam green bodies is investigated as well as the effect of using cross-linking agent versus the addition of just a binder. The presence of a cross-linked polymeric network within the green body increases its mechanical strength and minimizes crack formation during drying.