Surface Coatings of Solids

The properties of solid surfaces can be changed by coating while the rest of the material remains unchanged. Such coatings are numerous, and new applications are being continuously developed. 

A recent product called Sol-Gel (solution and gelling) coating has as its principle the following  

A solid surface is coated with a metal alkyl-oxide solution. 

The gel is exposed to high temperature, leaving behind a transparent coating. 

The alkyl oxide (Si[RO 4)w, is converted by a catalyst and, after dealkylation, it forms a polymer of (Si[OH]4) . On heating and dehydration, a coating of (Si[0]4)n is obtained. The thickness of the coating on aluminum (or other metal surface) can be 3 to 10 pm. 

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