Flat Glass Prestressing via Surface Composition Gradient
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Solution Overview
Problem
Current methods for compressively prestressing glass surfaces, such as chemical and thermal prestressing, require additional steps and significant engineering efforts, and there is a need for a more efficient method to achieve compressive prestressing during the glass production process.
Innovation Solution
A glass article with a composition that includes a core glass and surface glasses with specific thermal expansion coefficients, where the surface glass has a lower coefficient of thermal expansion than the core glass, allowing for compressive prestressing to be achieved through differences in thermal expansion during production, without the need for additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical prestressing is used to compressively prestress glass surfaces, then mechanical resistance is improved, but additional processing steps and engineering outlay are required
Solution Approach 1:
The glass composition is designed during the initial melting process to create a CTE gradient between surface and core, achieving compressive prestressing as an inherent property before any additional treatment. This preliminary design eliminates the need for subsequent chemical prestressing steps.
Solution Approach 2:
The invention changes the fundamental parameter of glass composition to achieve the desired effect. By adjusting the chemical composition to create different CTE values between surface and core regions, compressive prestressing is achieved through material property modification rather than additional processing steps.
2Strength
If thermal prestressing is used to compressively prestress glass surfaces, then mechanical resistance is improved, but additional processing steps and engineering outlay are required
Solution Approach 1:
The glass composition is designed during the initial melting process to create a CTE gradient between surface and core, achieving compressive prestressing as an inherent property before any additional treatment. This preliminary design eliminates the need for subsequent thermal prestressing steps.
Solution Approach 2:
The invention changes the fundamental parameter of glass composition to achieve the desired effect. By adjusting the chemical composition to create different CTE values between surface and core regions, compressive prestressing is achieved through material property modification rather than additional processing steps.
3Ease of manufacture
If a uniform glass composition is used, then manufacturing is simplified, but compressive prestressing cannot be achieved without additional steps
Solution Approach 1:
The glass article is designed with non-uniform local properties. The surface regions have a different chemical composition and CTE value compared to the core, creating localized characteristics that generate compressive prestressing while maintaining overall manufacturing efficiency.
Solution Approach 2:
The glass article functions as a composite material system with distinct surface and core regions having different chemical compositions. This composite structure, achieved through controlled composition gradients during melting, provides both the desired compressive prestressing and manufacturing efficiency.
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
This method enables the production of glass articles with compressive prestressing on the surface, enhancing mechanical resistance and safety without the need for additional chemical or thermal processing steps, thereby simplifying the production process and improving the glass's mechanical properties.
Implementation Method 1
the upper side surface glass having a CTEO which is lower by at least 0.6 ppm/K in comparison with the CTEK of the core glass... a compressive prestress σO on the upper side surface of at least 50 MPa is produced
Data Source
AI summary
The invention relates to glass articles, in particular flat glasses, in the case of which the surface material has gradient material properties as a result of targeted process control which in turn lead to compressive prestressing of the surface. The invention also relates to a method for producing the glass articles and the use thereof.