Lecture
Low–cost, highly porous Al2O3–SiO2-CaO ceramic foam were prepared by a novel and simple reactive foaming process. Green bodies were produced by mixing aluminium and SiO2 powders in an aqueous solution of sodium silicate and Ca(OH)2 and sintered in two steps: the first one was carried out by spark plasma (t=20 min, T= 800 C), , exploiting the oxygen exhchange reaction between the aluminium with the surrounding silicate matrix and the second one in conventional furnace, thus oxidizing the . The foams microstructures were characterized by SEM, XRD and X-ray microtomography (μ-CT), revealing open interconnected porosity and bimodal pore size distribution. For the presintered samples, EDS revealed the occurrence of the oxygen exchange reaction between metal and oxide, revealing an interpenetrated pattern Si-Al2O3 pattern. Lastly, the mechanical performance of the produced foams was evaluated by compressive test and indicated that by increasing the amount of SiO2 powder in the formulation, the amount of defects within the cell is reduced thus leading to stronger foams.
