News Detail
Advanced Chemical Tempering: The Secret Behind Mohs 9-Level Surface Hardness in Glass
Chemical tempering has emerged as a cutting-edge glass strengthening method, pushing surface performance far beyond conventional thermal tempering. While traditional tempered glass reaches surface hardness levels of 6–7 on the Mohs scale, chemically tempered glass can achieve Mohs 9, rivaling the hardness of sapphire.
1. What Is Chemical Tempering?
Unlike thermal tempering—which relies on rapid heating and cooling—chemical tempering involves immersing the glass in a molten salt bath, typically potassium nitrate (KNO₃), at around 400–450°C. During the process, smaller sodium ions in the glass are replaced by larger potassium ions, creating deep surface compression.
2. Why It Reaches Mohs 9 Hardness
The ion exchange creates a densely packed atomic surface layer. This compression dramatically improves the glass’s resistance to:
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Scratching (Mohs 9 = nearly scratch-proof by anything but diamond)
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Impact and bending forces
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Thermal and mechanical stress fractures
While the core of the glass remains unchanged, the outer layer behaves like an ultra-hard shield, perfect for high-wear applications.
3. Applications of Chemically Tempered Glass
Because of its enhanced surface properties and preserved optical clarity (no warping or distortion), chemically strengthened glass is widely used in:
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Smartphone screens and touch panels
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High-end watch crystals
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Aerospace instrumentation
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Precision optical devices and lab glassware
Conclusion
Chemical tempering transforms standard glass into an ultra-durable, scratch-resistant material with surface hardness up to Mohs level 9. This advanced process delivers the ideal balance of strength, clarity, and performance for industries that demand the highest surface protection.
