Tempered Glass Sheet Compressive Stress Layer Design
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Solution Overview
Problem
Tempered glass sheets used as cover glasses in touch panel displays, such as smartphones, are prone to breakage when dropped due to insufficient strength, and existing lithium aluminosilicate glasses face challenges in achieving a balance between compressive stress depth and chemical stability.
Innovation Solution
A tempered glass sheet with a specific glass composition ranging from 50% to 80% SiO2, 8% to 25% Al2O3, and controlled ratios of other oxides, subjected to ion exchange treatment to create a compressive stress layer with a depth of 50 μm to 200 μm and a compressive stress value of 200 MPa to 1000 MPa, enhancing chemical stability and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the glass composition is designed to increase the compressive stress value of the compressive stress layer, then the strength of the tempered glass sheet is improved, but the chemical stability is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass composition parameters (SiO2: 50-80%, Al2O3: 8-25%, B2O3: 0-10%, Li2O: 3-15%, Na2O: 3-21%, K2O: 0-10%, MgO: 0-10%, ZnO: 0-10%, P2O5: 0-15%) to achieve a balanced glass structure that provides sufficient compressive stress while maintaining chemical stability. This systematic parameter optimization resolves the contradiction between strength and chemical stability.
2Reliability
If the glass composition is designed to increase the depth of layer of the compressive stress layer, then the breakage probability is reduced, but the compressive stress value may be reduced excessively
Solution Approach 1:
The patent uses parameter changes by optimizing the glass composition to control both the depth of layer and compressive stress value of the compressive stress layer. The specific compositional ranges enable the glass to form a compressive stress layer with appropriate depth while maintaining sufficient compressive stress, thereby reducing breakage probability without excessively reducing strength.
3Strength
If the glass composition is unbalanced, then the compressive stress value can be increased, but devitrified stones are liable to be generated at the time of forming
Solution Approach 1:
The patent applies parameter changes by establishing balanced glass composition ranges that prevent devitrification during forming while maintaining sufficient compressive stress value. The controlled proportions of network formers (SiO2, B2O3, P2O5) and network modifiers (Li2O, Na2O, K2O, MgO, ZnO) ensure proper glass structure formation without generating devitrified stones, thus resolving the contradiction between strength and ease of manufacture.
4Stability of the object's composition
If the glass composition is designed to improve chemical stability, then the acid resistance is improved, but the ion exchange performance may be reduced
Solution Approach 1:
The patent uses parameter changes by carefully balancing the glass composition to achieve both chemical stability and good ion exchange performance. The specific ranges of network formers and modifiers create a glass structure that is chemically stable yet sufficiently reactive for ion exchange treatment, resolving the contradiction between chemical stability and ion exchange performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces the breakage probability of the glass when dropped by increasing the compressive stress layer depth and maintaining chemical stability, while also improving ion exchange performance and acid resistance.
Implementation Method 1
when a glass sheet to be tempered, which is formed of the lithium aluminosilicate glass, is immersed in a molten salt containing NaNO3 to ion exchange a Li ion in the glass with a Na ion in the molten salt
Data Source
AI summary
The present invention provides a tempered glass sheet having a compressive stress layer in a surface thereof, the tempered glass sheet including as a glass composition, in terms of mol %, 50% to 80% of SiO2, 8% to 25% of Al2O3, 0% to 10% of B2O3, 3% to 15% of Li2O, 3% to 21% of Na2O, 0% to 10% of K2O, 0% to 10% of MgO, 0% to 10% of ZnO, and 0% to 15% of P2O5.