Glass surface improvements by chemical reactions and thin film deposition

Abstract

Surface properties of primary glass are mainly a function of composition, method of forming and chemical interaction with an environment containing reactive gases such as H2O, CO2 or SO2. In the float glass process, different reactions will occur on the surface contacting the metal bath. Subsequent contact with water, detergents and packaging materials may further influence the surface condition of primary glass. Practical processes for improvement of glass surface properties are based on ion exchange reactions in the surface layer of the glass, or on surface reactions leading to deposition of thin films of various materials on the glass surface. Ion exchange reactions are involved in chemical strengthening processes and in dealkalization of glass surfaces for improved chemical resistance. Large-scale technologies have been developed for deposition of thin films on glass surfaces for improvement of chemical, mechanical and optical properties. The technically most important methods are vacuum deposition, sputtering, chemical vapor deposition, pyrolytic reactions, powder coating, dip coating and wet chemical film deposition. Depending on the desired function, the deposited films may consist of monolayers or multilayers of metals, oxides, nitrides, polymers or combinations of different materials. Glass surface preparation, adhesion and durability under various environmental conditions are also key factors for the performance of the coated glass.