Ceramics-Silikáty 55, (3) 240 - 245 (2011)

Alumina foam was prepared by the direct foaming method. The foam was stabilized by in situ partially hydrophobized particles of Al₂O₃. Dodecylbenzenesulphonic acid was used for hydrophobization and it also acted as a foaming agent. The composition of the starting suspensions (Al₂O₃, boehmite, dodecylbenzenesulphonic acid and water) were varied according to factorial design. The resulting properties observed were: foam ratio, foam shrinkage on drying and sintering, bulk density and porosity of ceramic foams, average pore size and compressive strength. The final properties of foams dependent on statistically significant factors (boehmite, dodecylbenzenesulphonic acid) were evaluated by common software. The foam ratio decreased and the bulk density of the alumina foams increased with increasing quantity of the dodecylbenzenesulphonic acid (0.1-0.2 wt.%). Bulk density of alumina foams ranged from 88 to 155 kg/m³ and average pore size reached 111 μm to 215 μm depending on the quantity of the dodecylbenzenesulphonic acid. The microstructure of ceramic foams reached high porosities ranging from 96 to 98 %. The compressive strength of the alumina foams increased with increasing quantity of boehmite (1-3 wt.%) and it reached values of 333 kPa.