How Many Types of Temper Glass ?
What Is Tempered Glass ?
Tempered glass is also called strengthened glass. It uses physical or chemical methods to form a compressive stress layer on the glass surface. The glass itself has a high compressive strength and will not cause damage. When the glass is subjected to external forces, this pressure layer can offset part of the tensile stress and avoid the glass from breaking. Although the interior of the tempered glass is in a state of large tensile stress, there are no defects inside the glass and it will not cause damage, thereby achieving the purpose of improving the strength of the glass.
Tempered glass is a secondary processed product of flat glass. The processing of tempered glass can be divided into physical tempering and chemical tempering.
Next, let's first introduce these two tempering processes:
Physical tempering:
Physical tempered glass , also known as quenched tempered glass.
It is made by heating ordinary flat glass in a heating furnace to a temperature close to the softening temperature of the glass ( generally above 630°C, and some even to 700°C ), eliminating internal stress through its own deformation, and then removing the glass from the heating furnace. High-pressure cold air is blown to both sides of the glass with a multi-head nozzle to make it quickly and evenly cool to room temperature, and then tempered glass can be made.
This kind of glass is in a stress state of internal tension and external compression. Once it is partially damaged, stress release will occur, and the glass will be broken into countless small pieces. These small pieces have no sharp edges and are not easy to hurt people.
Chemical tempering:
Glass is tempered by changing the chemical composition of the surface of the glass to improve its strength. Generally, ion exchange is used for tempering.
The method is to immerse silicate Glass Containing alkali metal ions into molten lithium (Li+) salt, so that the Na+ or K+ ions on the surface of the glass are exchanged with Li+ ions, and a Li+ ion exchange layer is formed on the surface. Since the expansion coefficient of Li+ is smaller than that of Na+ and K+ ions, the outer layer shrinks less and the inner layer shrinks more during the cooling process.
When cooled to room temperature, the glass is also in a state of tension in the inner layer and compression in the outer layer. The effect is similar to that of physical tempered glass.
Perhaps, after reading this, you still don't quite understand the connection and difference between them.
So we conclude below table to directly see: Comparison of THERMAL TEMPERED GLASS and CHEMICALLY TEMPERED GLASS.
Glass : The Difference Between Thermal Tempered And Chemically Strengthen
| Thermal Tempered .VS. Chemically Strengthen | ||
| Thermal Tempered | Chemically Strengthen | |
| Processing temperature: | Temperature of 600℃-700℃ (close to the softening point of glass) | 400℃-450℃ |
| Processing principle : | Quenching, compressive stress is formed internally | Potassium and sodium ion replacement + cooling, also compressive stress |
| Processing thickness: | 0.15mm-50mm | 3.2mm-35mm |
| Surface stress value | 90Mpa-140Mpa | 450Mpa-650Mpa |
| Fragment status: | Granular | lumpy |
| Broken state: |  |  |
| Impact strength: | Glass thickness ≥6mm has advantages | Advantages of glass <6mm |
| Bending strength : | Chemical tempering is higher than physical tempering | |
| Optical properties: | Chemical tempering is better than physical tempering | |
| Surface roughness : | Chemical tempering is better than physical tempering | |
Okay, now we have learned that there are two types of tempering: Thermal Tempered and chemically Strengthen. Their principles, processing techniques, and applicable thickness types, and the final hardness they can achieve are all different. So you may have a question : How do I test tempered glass by myself ?
However, no matter which one, the ultimate goal achieved is the same: that is, to improve the surface hardness of the glass and make the glass more impact and shock resistant.
Tibbo Glass has been specialising in the production of Toughened Glass for over 20+ years, with toughening grades up to IK08/09/10. We specialise in the production ofelectrical and electronic glass, display cover glass, AG Glass, AR Glass, AF coated glass, ITO Coated Glass, FTO conductive glass and more. Any questions , please feel free to contact.