Chemical treatment is the most widely used and effective method for imparting scratch resistance to glass, leveraging ion-exchange processes that fundamentally alter the surface chemistry of the glass to create a compressive layer that resists scratch propagation. This technology is at the heart of most high-performance scratch-resistant glass products on the market today.

The ion-exchange process, also known as chemical strengthening, involves immersing glass in a molten salt bath, typically containing potassium nitrate, at temperatures around 400°C to 450°C. During this process, smaller sodium ions in the glass surface are replaced by larger potassium ions from the salt bath. The presence of larger ions in the surface creates compressive stresses that make the glass more resistant to scratch and impact damage. The depth of the compressive layer, known as the depth of layer (DOL), is a critical parameter that determines the scratch resistance and strength of the glass.

Recent innovations in chemical strengthening include the development of glasses with a non-zero varying sodium concentration extending from the surface to a depth of the glass article, combined with a compressive layer extending from the surface to a spike depth of 4 to 8 micrometers and a molar ratio of potassium oxide to sodium oxide averaged over a distance of 0.4 micrometers from the surface that is from 0.6 to 1.6. This precise control over surface chemistry enables manufacturers to optimize scratch resistance while maintaining other critical properties such as optical clarity and impact resistance.

Chemical treatment is particularly important for thin glass applications, where mechanical strengthening methods are less effective. SCHOTT AS 87 eco is an ultra-thin aluminosilicate glass with extremely high levels of bending and impact strength and superior scratch resistance, achieved through chemical strengthening. The growing demand for thin, lightweight glass in consumer electronics and automotive displays is driving innovation in chemical strengthening technologies. For more information on chemical treatment for scratch-resistant glass, visit Scratch Resistant Glass Market Report.

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