Coated Glass Stress Profile for Scratch and Strength
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Solution Overview
Problem
Strengthened glass-based articles face challenges in maintaining reliability and flexural strength due to steep stress profiles, especially when hard, brittle coatings are applied, which can deteriorate their performance under drop-induced damage and scratches.
Innovation Solution
A coated glass-based article with a laminated structure featuring a glass substrate and a coating with a higher Young's modulus than the substrate, having a designed stress profile with a steep tangent at the surface and a shallow tangent deeper within, achieved through modified ion exchange processes and covalent bonding of cladding substrates, providing enhanced resistance to deep flaws and scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hard, brittle coatings are applied to strengthened glass-based articles, then scratch resistance is improved, but flexural strength performance deteriorates
Solution Approach 1:
The patent modifies the stress profile parameters of the glass substrate by controlling the ion exchange process to create a specific compressive stress distribution. This engineered stress profile compensates for the stress introduced by hard coatings, maintaining flexural strength while enabling scratch resistance. The stress profile is characterized by a compressive region extending to a controlled depth with specific stress magnitudes at different depths.
Solution Approach 2:
The patent creates a composite structure consisting of the glass substrate with engineered stress profile and the hard coating layer. The glass substrate serves as the base material with tailored mechanical properties, while the coating provides surface hardness. The interface between these materials is designed to ensure compatibility and prevent failure, achieving both scratch resistance and maintained flexural strength.
2Stress or pressure
If steep stress profiles are used in strengthened glass, then surface compressive stress is maximized, but reliability under drop-induced damage decreases
Solution Approach 1:
The patent applies different stress characteristics to different depth regions of the glass substrate. The surface region has high compressive stress for scratch resistance, while the deeper regions have gradually reducing stress to avoid brittleness. This localized stress distribution optimizes both surface performance and overall reliability, preventing catastrophic failure under drop-induced damage.
3Ease of manufacture
If standard ion exchange processes are used, then manufacturing simplicity is maintained, but sensitivity to initial flaw populations increases
Solution Approach 1:
The patent modifies the ion exchange process parameters, including temperature, time, and chemical composition, to create an engineered stress profile that reduces sensitivity to initial flaws. These parameter changes are implemented within existing manufacturing capabilities, maintaining relative simplicity while significantly improving reliability by creating a stress distribution that prevents flaw propagation.
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 optimized stress profile significantly increases the glass-based article's strength protection against deep flaws and maintains flexural strength, improving mechanical reliability and scratch resistance compared to standard ion-exchanged or laminated glass-based articles.
Implementation Method 1
In strengthened glass-based articles, such as chemically strengthened glass articles, compressive stress is highest or at a peak at the glass surface and reduces from a peak value moving away from the surface
Implementation Method 2
the glass-based core substrate sandwiched between a glass-based first cladding substrate and a glass-based second cladding substrate, the first cladding substrate bonded to the first side and the second cladding substrate bonded to the second side by a covalent bond
Data Source
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AI summary
Coated glass-based articles and methods of manufacture disclosed. An article comprises a chemically strengthened glass-based core substrate having a first surface and a second surface, a chemically strengthened glass-based first cladding substrate having a third surface directly bonded to the first surface to provide a first core-cladding interface and a chemically strengthened glass-based second cladding substrate having a fourth surface directly bonded to the second surface to provide a second core-cladding interface, wherein the core substrate is bonded to the first cladding substrate and the second cladding substrate, and there is a coating on the first cladding substrate.