How is tempered glass tempered?

Tempered glass is actually a kind of prestressed glass. In order to improve the strength of glass, chemical or physical methods are usually used to form compressive stress on the glass surface. When the glass is subjected to external force, the surface stress is first offset, thereby improving the bearing capacity and enhancing the resistance of the glass itself. Wind pressure, cold and heat, shock, etc.

1. Physical tempering method

The principle of the physical tempering method is to heat the glass to a suitable temperature and then cool it quickly, causing the glass surface to shrink sharply and produce compressive stress. The middle layer of the glass cools slowly, and it is too late to shrink, so tensile stress is formed, which makes the glass obtain higher strength. Generally speaking, the higher the cooling strength, the greater the strength of the glass.

2. Chemical toughening method

The chemical tempering method refers to a tempering method that changes the composition of the glass surface through a chemical method and increases the surface lamination stress to increase the mechanical strength and thermal stability of the glass. Because it strengthens glass through ion exchange, it is also called ion exchange enhancement method. According to the type of ion exchange and the temperature of ion exchange, it can be divided into ion exchange methods below the transition point and ion exchange methods above the transition point temperature.

The principle of the chemical enhancement method is to change the surface composition of the glass according to the mechanism of ion diffusion. The glass is immersed in a high-temperature molten salt at a certain temperature. The alkali metal ions in the glass and the alkali metal ions in the molten salt are caused by diffusion. Mutual exchange occurs, resulting in "crowding" phenomenon, causing compressive stress on the glass surface, thereby increasing the strength of the glass.