Porous and Dense Composites from Sol-Gel

Abstract

The sol-gel method has been widely studied recently for the preparation of bulk glasses, thin films, and porous solids.¹ One of its advantages as a process for the fabrication of ceramics is the possibility of the use of low temperatures. Another advantage is the fact that liquid solutions are mixed and, hence, good homogeneity is easily achieved. In this paper, the preparation of one type of composite based on the dispersion of solid particles in a sol-gel matrix is described. A second type of composite utilizing the connective pores of the sol-gel matrix has also been made by the impregnation of organic monomers followed by polymerization. These are thus oxide-organic polymer composites. Finally, results are presented for “triphasic” composites made by the impregnation of polymers into a porous two-phase composite of the first group. These three types of composite are described by figure 1. It should be mentioned that other composites have also been made by the exploitation of the uniqueness of the sol-gel technique. These include glass-ceramics², “diphasic” glass-ceramics³, “diphasic” ceramic-metal xerogels⁴ , ceramic-ceramic composites⁵, and moisture sensitive glasses⁶.