Novel ceramic foams from crystals of AlCl3((Pr2O)-O-i) complex

In this paper we report a novel process for the production of ultralight ce llular ceramics. The foams are generated by the heat treatment of crystals of the aluminum chloride isopropyl ether complex [AlCl3((Pr2O)-O-i)]. The c rystals, which are the only foam precursor, are obtained from concentrated solutions of AlC3, (Pr2O)-O-i, and CH2Cl2. The foams consist of an arrangem ent of closed cells, 50-300 mu m in diameter, having cell walls approximate ly 1-2 mu m thick. An exceptionally high porosity is obtained ranging from 94 to 99%, and the cellular structure is retained during heating at 1500 de grees C. The foaming mechanism involves two consecutive nonhydrolytic sol-g el chemical reactions and physical processes including crystal dissociation , solvation, phase separation, and foaming, While other foaming mechanisms cited in the literature utilize one or more of the processes above, no anal og mechanism exists in the organic, ceramic, or metal foam production proce sses, The effectiveness of the process originates from an initial precursor which contains all the necessary foaming components in such a way that the application of mild heating accelerates its transformation to a solid, dry , ultralight foamed material.