The Chemical tempering of glass is obtained by immersing the glasses to be treated in a bath of molten salts of potassium at temperatures higher than 400°C. The potassium ions (K+), contained in the salt, are to replace the sodium ions (Na+) with smaller diameter contained in the glass surface, determining the establishment of compressive stresses over the entire surface and over the edges.
The properties of mechanical resistance to bending of a chemically tempered glass are higher by five to ten times compared to those of a thermally tempered glass subjected to the same force. This particular production process also increases the impact resistance: a thermally tempered glass has an impact strength with a steel ball, which is almost twice that of normal glass, while the impact resistance of a chemically tempered glass is five times that of normal glass and ensures absolute flatness without distortion. You can chemically temper all types of normal “float” glass. The color green will undergo ion exchange inferior to others. Coated glass and glass with a chemical composition different from conventional grades of glass are not normally hardenable. The parameters of the chemical tempering process may vary depending on the type of glass and the specific tempering requests.
By the chemical tempering it is possible to temper glass with thickness min 0,5 mm and also glass with particular geometric shape, maintaining a high optical quality. This feature allows the use of tempered glass in various fields such as automotive, electronics, architectural, aeronautical, naval and military.