Porous alumina-spinel ceramics for high temperature applications

In order to reduce energy costs, high-temperature insulation porous refractory ceramics have been subjected to increasing demands. Among the techniques used to produce these materials (such as the addition of foaming agents and organic compounds), the pore generation via phase transformation presents key aspects, such as easy processing and the absence of toxic volatiles. In this study, this technique was applied to produce porous ceramics by decomposing an aluminum–magnesium hydro-carbonate known as hydrotalcite (Mg6Al2(CO3)(OH)16·4H2O). It was found out that by using this complex compound, a large fraction of pores can be generated and kept at high temperatures (above 1300 °C) due to the in situ formation of spinel-like phases (MgAl2O4).