Cellular ceramics via alkane phase emulsified powder suspensions

An innovative foaming method to produce macroporous cellular ceramics using surfactants as emulsion and wet foam stabilizers is established. The technology relies on the transition of a stabilized aqueous ceramic powder suspension containing a homogeneously dispersed alkane phase, here called emulsified suspensions, into cellular ceramics. The stabilization of the powder suspension and the emulsion is realized with particular emphasis on the interaction of both systems providing enduring stability. In contrast to the more conventional direct foaming methods, foaming is here provided by the evaporation of the emulsified alkane droplets. Hence, the droplets expansion kinetics is crucial in this technique as it will determinate the cell size of the cellular materials. The wet foams can be simply consolidated by the expansion of the droplets due to foaming and concurrent drying. Here, the particles network between bubbles plays an important role ensuring the high green stability. A strong ceramic cellular microstructure is reached during sintering.