Production of fire clay porous structure with no aligned macro porosity from water-based slurry by freeze casting process: A new approach

Abstract Despite the directional growing of ice crystals, fire clays structures with non-allied macroscopically porosity were prepared using a water-based freeze casting process. Pores were generated subsequently by sublimation of the columnar ice during freeze casting. By sintering this green body, a fire clay with the amount of porosity as high as 74% was obtained. Initially, the cell size and size distribution of the fire clay foams could be efficiently adjusted by the control of some parameters such as type of fire clay and gelatin content. The influence of each parameter on the properties of the obtained structures were investigated. The analysis suggests as useful this route as a new approach to produce spherical porous ceramics by freeze casting. The characteristics (morphology, strength, chemical and thermal resistance) of the foams suggest that they could be employed in applications as thermal insulation and soundproofing materials.