A process for foaming ceramic foams, in which the ceramic foams are
produced from a precursor or a mixture of precursors which contain at
least one ceramic-forming element and liberates at least one volatile
reaction product during an inorganic gelation process. In one embodiment,
foaming is based on a precursor containing crystals of the
AlCl.sub.3(Pr.sup.i.sub.2O) complex. The decomposition of the initial
precursor produces polymerizing species dissolved in liquid isopropyl
chloride. The solvent and growing AlO.sub.xCl.sub.y(OPr.sup.i).sub.z
species are mixed homogeneously so that the boiling point of the solution
is raised above the boiling point of the pure isopropyl chloride.
Polymerization takes place in the liquid until a critical polymer size is
attained, whereupon a phase separation into polymer rich and solvent rich
regions occurs. Since the expelled solvent is suddenly above its boiling
point, bubbles start forming instantly. Foam stabilization takes place as
a result of gelation in the polymer rich regions which comprise the cell
walls in the foam. The net result of the process is a gelled ultra light
foam.