The sol-gel process is a versatile solution process for making advanced materials, including ceramics and organic-inorganic hybrids. In general, the sol-gel process involves the transition of a solution system from a liquid "sol" (mostly colloidal) into a solid "gel" phase. Utilizing the sol-gel process, it is possible to fabricate advanced materials in a wide variety of forms: ultrafine or spherical shaped powders, thin film coatings, fibers, porous or dense materials, and extremely porous aerogel materials. An overview of various sol-gel processes is illustrated above in a graphical form.
The starting materials used in the preparation of the "sol" are usually inorganic metal salts or metal organic compounds such as metal alkoxides. In a typical sol-gel process, the precursor is subjected to a series of hydrolysis and polymerization reactions to form a colloidal suspension, or a "sol". Further processing of the "sol" makes it possible to make materials in different forms.
Durable thin films with a variety of properties can be deposited on a substrate by spin-coating or dip-coating. When the "sol" is cast into a mold, a "wet gel" will form. With further drying and heat treatment, the "gel" is converted into dense materials. If the liquid in a wet "gel" is extracted under a supercritical condition, a highly porous and extremely low-density material called "aerogel" is obtained. As the viscosity of a "sol" is adjusted into a given viscosity range, fibers can be drawn from the "sol". Ultrafine and uniform powders are formed by precipitation, spray pyrolysis, or emulsion techniques.
In offering a Total Sol-Gel Solution, Chemat supplies precursors and equipment specifically suited for sol-gel processing, together with the R&D Services to assist customers in developing entire systems for production of unique advanced materials.
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