Development and mechanical characterization of novel ceramic foams fabricated by gel-casting

Porous ceramic materials are of considerable interest for a variety of chemical and industrial applications in extremely harsh conditions, particularly at very high temperatures for long times. A modified gelcasting process employing agar as a natural gelling agent and polyethylene spheres as pore formers was exploited to produce porous ceramic bodies. Alumina and alumina-ZrO2 (AZ) powders were used to prepare samples having a porosity of about 65-70-75 vol%. The composite powder was produced by a surface modification route, i.e. by coating a well dispersed alphaalumina powder with a zirconium chloride aqueous solution. Upon thermal treatment, ultra-fine tetragonal zirconia grains formed on the surface of the alumina particles. SEM observations and image analysis were used to characterize the microstructure of porous samples and uniaxial compressive tests were used to measure their mechanical behavior. Corresponding author: Jean-­‐Marc Tulliani, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Torino -­‐ Italy. Tel: +39(0)11 564 47 00. Fax: +39(0)11 564 46 64. E-­‐mail: [email protected]