High Young’s Modulus Alkali Glass for Sharp-Contact Resistance
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Solution Overview
Problem
Existing glasses and glass-based articles used in electronic devices are vulnerable to damage from accidental drops and flexural stresses, particularly when they have a low Young's modulus and are susceptible to sharp contact failures.
Innovation Solution
A glass composition comprising 52-62 mol. % SiO2, 9-11.5 mol. % Al2O3, 18.3-26 mol. % MgO, 0-6 mol. % Na2O, 5.3-15 mol. % Li2O, and less than 2.6 mol. % CaO, which can be ion-exchanged to create a compressive stress layer and a central tension region, enhancing mechanical properties like Young's modulus and fracture toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If thin glass is used to reduce material costs and device profile, then manufacturing cost and device thickness are improved, but the glass becomes more susceptible to flexural and sharp contact failures
Solution Approach 1:
The patent changes the chemical composition parameters of the glass by incorporating specific amounts of lithium oxide (5-20 mol%) and magnesium oxide (10-30 mol%) along with aluminum oxide (5-15 mol%) to achieve a Young's modulus of at least 86 GPa, thereby improving strength while maintaining thin dimensions
Solution Approach 2:
The patent creates a composite glass structure through ion-exchange process that combines a compressive stress layer (formed by replacing lithium ions with larger alkali ions) with a central tension region, resulting in a multi-layered composite structure that enhances overall strength and resistance to failure
2Strength
If ion-exchange is performed to introduce compressive stress layer and strengthen the glass, then resistance to flexural failure is improved, but the glass remains vulnerable to dynamic sharp contacts
Solution Approach 1:
The patent modifies the base glass composition parameters before ion-exchange by adding specific amounts of magnesium oxide (10-30 mol%) and aluminum oxide (5-15 mol%) to achieve a Young's modulus of at least 86 GPa, which provides inherent resistance to sharp contact failures that complements the compressive stress layer formed by ion-exchange
Solution Approach 2:
The patent creates a composite structure combining two strengthening mechanisms: the compressive stress layer formed by ion-exchange (replacing lithium ions with larger alkali ions) and the high Young's modulus matrix material (achieved through specific MgO and Al2O3 content), resulting in a multi-functional composite that resists both flexural failure and dynamic sharp contacts
3Strength
If high magnesium oxide content is used to increase Young's modulus, then mechanical strength is improved, but glass formation and processing may be affected
Solution Approach 1:
The patent optimizes the magnesium oxide content to 10-30 mol% (specifically 18.3-26 mol% in some embodiments) and balances it with aluminum oxide (5-15 mol%, specifically 9-11.5 mol%) and lithium oxide (5-20 mol%, specifically 5.3-15 mol%) to achieve the desired Young's modulus while maintaining proper glass formation and processing characteristics
Solution Approach 2:
The patent differentiates the functional roles of various oxide components in the glass matrix: magnesium oxide primarily contributes to Young's modulus and mechanical strength, aluminum oxide provides structural network formation and stability, and lithium oxide enables ion-exchange capability. This localized functional assignment allows each component to be optimized for its specific purpose while maintaining overall glass formability
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 glass composition achieves high Young's modulus and fracture toughness, reducing the likelihood of damage from impacts and improving manufacturability, while maintaining processability.
Implementation Method 1
ion-exchanging the glass-based substrate in a first molten salt bath to form a glass-based article, wherein the glass-based article comprises a compressive stress layer extending from a surface of the glass-based article to a depth of compression
Data Source
AI summary
A glass comprising 52-62 mol. % SiO2; 9-11.5 mol. % Al2O3; 18.3-26 mol. % MgO; 0-6 mol. % Na2O; 5.3-15 mol. % Li2O; and less than 2.6 mol. % CaO. A glass-based article comprising a compressive stress layer extending from a surface of the glass-based article to a depth of compression; a central tension region; and a composition at a center of the glass-based article comprising the glass. A method for ion-exchanging a glass-based substrate, the method comprising ion-exchanging the glass-based substrate in a first molten salt bath to form a glass-based article wherein the glass-based article comprises a compressive stress layer extending from a surface of the glass-based article to a depth of compression, the glass-based article comprises a central tension region, and the glass-based substrate comprises the glass.