Stabilization of silica sols derived from an inexpensive, fully inorganic precursor and their use

An amorphous, aluminosilicate-based mineral has been dissolved in acidic water and water–ethanol solutions, respectively, for subsequent use as a binder for inorganic fiber mats. In this communication, the focus is put on the stability of the sols towards subsequent gelation, an important parameter for potential commercialization of the process. The sols were characterized by determination of the dissolution time, elemental analysis, viscosity, and contact angle measurements. Dried gels were characterized by TG-IR and sprayed and gelled sols by light microscopy, respectively. It was found that the addition of ethanol to the sol resulted in a pronounced increase of the gel time, and consequently the time-window for sol processability was widened.