The cellular structure, in alkali activated metakaolin-based suspensions, foamed by intensive mechanical stirring, is stabilised by the viscosity increase caused by gelation, in a condition of ‘inorganic gel casting’. The approach is so flexibile that it may be applied to mixtures embedding fillers, such as reactive γ-Al₂O₃ powders, playing a fundamental role upon ceramic conversion. The present study is dedicated to highly porous cordierite foams, obtained including talc as further component, and applying a heat treatment at 1200-1250 °C, in air. A key intermediate step is represented by the removal of Na⁺ ions from ‘green’ foams, by ion exchange in ammonium nitrate solution (24 h), before ceramization. Direct ceramization is also feasible, if the gelation is achieved by reaction with tetra-methyl-ammonium hydroxide, instead of NaOH. The new gels are effective in yielding phase-pure cordierite, otherwise feasible, with NaOH activation, by means of much longer ion exchange treatment (120 h).

在“无机凝胶浇铸”条件下，通过剧烈的机械搅拌而发泡的碱活化的偏高岭土基悬浮液中的细胞结构通过胶凝引起的粘度增加而得以稳定。该方法是这样flexibile它可以被施加到嵌入的混合物的填料，如反应性的γ-Al _2成ö _3成粉末，在打陶瓷转换根本性的作用。本研究致力于高孔隙度的堇青石泡沫，该泡沫包括滑石粉作为其他成分，并在空气中于1200至1250°C的温度下进行了热处理。关键的中间步骤是除去Na ⁺陶瓷化之前，通过在硝酸铵溶液中进行离子交换（24小时），从“绿色”泡沫中提取离子。如果通过与氢氧化四甲基铵而不是NaOH反应实现凝胶化，则直接陶瓷化也是可行的。新的凝胶可有效地产生相纯的堇青石，否则可通过更长的离子交换处理（120小时）来活化NaOH。