Deep Compressive Layer Chemically Strengthened Glass
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Solution Overview
Problem
Chemically strengthened glasses face challenges in maintaining survivability under tensile stresses and deep flaws, especially when subjected to contact with hard or sharp surfaces, as existing technologies do not effectively provide sufficient compressive stress profiles to prevent fracture.
Innovation Solution
The development of chemically strengthened glass articles with deep compressive layers extending up to 125 μm, featuring specific compressive stress profiles with slopes ranging from -0.4 MPa/μm to -3.0 MPa/μm, achieved through ion exchange processes that create alkali aluminosilicate glasses with controlled compressive stress distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemically strengthened glass uses traditional compressive stress profiles, then manufacturing is simpler, but survivability under tensile stress and deep flaws is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the compressive stress profile parameters, specifically implementing a linear portion with controlled slope (ma) extending to a specific depth (da) within the glass article. This controlled parameter adjustment creates optimal stress distribution that enhances survivability under tensile stress and deep flaws without overly complicating the manufacturing process.
Solution Approach 2:
The patent implements local quality by creating different stress profile characteristics at different depths within the glass. The compressive stress profile has a specific linear portion extending from the surface to depth da with slope ma, while other regions have different characteristics. This localized stress optimization improves reliability where needed most while maintaining manufacturing feasibility.
2Reliability
If chemically strengthened glass increases depth of compression to arrest deep flaws, then resistance to deep flaws improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses parameter changes to define the depth of compression (DOC) as a specific proportion of glass thickness (0.1t ≤ DOC ≤ 0.25t), rather than requiring absolute precision. The linear portion depth (da) is set equal to DOC, and the slope (ma) is constrained within a range (−0.4 MPa/μm ≥ ma ≥ −3.0 MPa/μm). These parameter specifications provide manufacturing flexibility while ensuring adequate flaw arrest capability.
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
These glass articles exhibit improved resistance to fracture and survivability by arresting deep flaws and minimizing the likelihood of flaw growth under external stresses, enhancing their performance in drop tests and bending conditions.
Implementation Method 1
achieved through ion exchange processes that create alkali aluminosilicate glasses with controlled compressive stress distributions
Data Source
AI summary
Chemically strengthened glass articles having at least one deep compressive layer extending from a surface of the article to a depth of compression DOC of at least about 125 μm within the glass article. The compressive stress profile includes a single linear segment or portion extending from the surface to the depth of compression DOC. Alternatively, the compressive stress profile may include an additional portion extending from the surface to a relatively shallow depth and the linear portion extending from the shallow depth to the depth of compression.