| Processing routes to make oxide ceramic foams of porosity more than 70% with pore sizes in the range of 0.1-4 mm are reviewed. Microstructures and mainly characteristics of pores produced by incorporation of fugitives, infiltration through 3D-preforms, direct casting of foams are compared. Emphasis has been given to the versatile processes with use of natural additives, which allow in controlling microstructural features while improving the desired mechanical property. The critical step in setting of ceramic foam through direct casting foaming process, i.e. stabilization of bubbles during consolidation, is being highlighted emphatically with use of water soluble additives. |
