| 摘要 |
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</SUB>(Pr<SUP>i</SUP><SUB>2</SUB>O) complex. The decomposition of the initial precursor produces polymerizing species dissolved in liquid isopropyl chloride. The solvent and growing AlO<SUB>x</SUB>Cl<SUB>y</SUB>(OPr<SUP>i</SUP>)<SUB>z </SUB>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.
|
