Alkali Aluminosilicate Glass Ion Exchange for Foldable Display Strength
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Solution Overview
Problem
Foldable display glasses experience reduced flaw-arresting effect and failure when bent due to the limitations of surface compressive layers, which are not effective for deep surface flaws under significant bending stresses.
Innovation Solution
Development of alkali aluminosilicate glasses that can be ion-exchanged to achieve ultra-high peak compressive stress of up to 1500 MPa, maintaining net compression and containing surface flaws even under tight bending radii, through immersion in a potassium salt ion exchange medium at controlled temperatures and times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chemically tempered glass is used to produce surface compressive layer, then flaw-arresting effect is achieved, but the effect is reduced when glass is bent due to deep surface flaws
Solution Approach 1:
The patent changes the chemical composition parameters of the glass, specifically increasing Al2O3 content to 17-23 mol% and controlling RO content to achieve 21-30 mol% total, which enables the glass to achieve ultra-high peak compressive stress of 1000-1500 MPa through ion exchange, resolving the contradiction between flaw-arresting capability and bending strength
Solution Approach 2:
The patent creates a composite ion-exchanged glass structure with a compressive layer containing exchanged alkali metal ions (e.g., potassium ions replacing sodium ions) that provides both flaw-arresting capability and enhanced bending resistance through the combination of chemical composition control and ion exchange treatment
2Strength
If surface compressive layer is applied to glass, then shallow flaws are arrested, but deep surface flaws cause failure under bending stress
Solution Approach 1:
The patent modifies the glass composition by increasing Al2O3 to 17-23 mol% and adjusting RO content to achieve optimal ion exchange characteristics that produce ultra-high compressive stress (1000-1500 MPa), which effectively arrests both shallow and deep surface flaws under bending conditions
Solution Approach 2:
The patent applies ion exchange treatment in advance to create a deep compressive layer that pre-compresses the glass surface, providing proactive protection against both shallow and deep flaws before bending stresses are applied during use
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 glasses exhibit high strength and fracture toughness, preventing fractures from applied stresses and maintaining integrity under bending, suitable for flexible and foldable display applications.
Implementation Method 1
The glasses described herein may be ion exchanged to achieve a peak compressive stress of about 1000 MPa or more, and up to about 1500 MPa
Data Source
AI summary
Alkali aluminosilicate glasses that may be ion exchanged to achieve ultra-high peak compressive stress. The glasses may be ion exchanged to achieve a peak compressive stress of at least about 1000 MPa and up to about 1500 MPa. The high peak compressive stress provides high strength for glasses with shallow flaw size distributions. These glasses have high Young's moduli, which correspond to high fracture toughness and improved failure strength and are suitable for high-strength cover glass applications that experience significant bending stresses in use such as, for example, as cover glass in flexible displays.