What's glass chemical tempered?

I. Definition and Advantages

Chemical tempered glass is a essentially type of prestressed glass. To boost its strength, we usually use chemical or physical methods to form compressive stress on the glass surface. When the glass bears external force, it first offsets the surface stress-this not only improves the load-bearing capacity but also enhances the glass' own wind pressure resistance, temperature resistance, impact resistance, and more.

There are four main advantages of chemical tempered glass:

1. Its strength is 5 to 10 times higher than that of ordinary glass. The bending strength is 3 to 5 times that of ordinary glass, and the impact strength is 5 to 10 times higher. While increasing strength, it also improves safety. Compared with glass of the same thickness, chemical tempering is obviously better than physical tempering in terms of strength.

2. Safety in use is the second major advantage of tempered glass. Its increased load-bearing capacity improves its fragile nature. The resistance to sudden temperature changes of chemical tempered glass is 2 to 3 times higher than that of ordinary glass. Generally, it can withstand a temperature difference of more than 150°C, which has a significant effect on preventing thermal breakage, and there is absolutely no spontaneous explosion.

3. Due to the different processing methods, tempered products have no deformation at all-they won't change the product shape, and there is no restriction on the product shape; all can be tempered. For example, curved, cylindrical, bottle-shaped, box-shaped, and flat-shaped glass can all be processed without deformation.

4. It has a significant tempering effect on ultra-thin products. The existing technology is very mature, and the tempering effect is excellent for glass with a thickness of 0.2 to 5.0 mm, without causing bending deformation.

II. Manufacturing Principle

Chemical tempered glass is produced using a low-temperature ion exchange process. The so-called low temperature refers to the range where the exchange temperature does not exceed the glass transition temperature, which is relative to the high-temperature ion exchange process that operates above the transition temperature and below the softening point.

The simple principle of the low-temperature ion exchange process is: in an alkali salt solution at around 400°C, the ions with smaller radii in the glass surface layer are exchanged with the ions with larger radii in the solution. For example, lithium ions in the glass are exchanged with potassium or sodium ions in the solution, and sodium ions in the glass are exchanged with potassium ions in the solution. The difference in the volume of alkali ions forms an embedded compressive stress on the glass surface.

The number of large ions embedded into the glass surface is proportional to the surface compressive stress, so the number of ion exchanges and the depth of the exchanged surface layer are the key indicators of the strengthening effect. Since the ion exchange layer proceeds uniformly, the chemical tempering glass method has a significant effect on strengthening thin glass, especially suitable for strengthening glass with a thickness of less than 5mm.

III. Application Scope

Chemical tempered glass is suitable for use in the following architectural and industrial scenarios: places that require weight reduction, while having certain requirements for impact strength, bending strength, and resistance to thermal shock. Examples include: mobile phone screen glass covers, computer and TV screen glass, space shuttles, fighter jet movable covers, kitchen cabinet glass, decorative glass, electronic panel glass, windows and ceilings of agricultural greenhouses, door and window glass of mobile houses, and so on.

With mature process technology, ultra-low energy consumption, and high-quality products, it has become a trend to use chemical tempering for more products.