Microstructure, permeability and mechanical behaviour of ceramic foams

Abstract

This work is part of a model study aimed at upgrading the technique of creating porosity via the incorporation of organic particles used in traditional ceramics, exploring at the same time colloidal processing from coagulated slurries. The method described in another work, based on the manipulation of short-range repulsive (lubricating) hydration force and long-range attractive van der Waals force, was used to pack to a high density a bimodal mixture of submicron ceramic particles (matrix) and much larger organic particles (inclusions) during consolidation by pressure filtration of dispersed suspensions coagulated by added electrolyte. Investigations carried out to produce strong porous ceramic bodies, with a tailored pore structure, are described. The liquid-like rheology of the saturated consolidated body produced from the coagulated suspension explains the characteristic features observed after burn-up of the organic inclusions and sintering. The porous ceramic body reflects its processing history, which can be observed in its microstructure, mechanical behavior and gas permeability.