Zircon-Compatible Glass Composition for Down-Draw Manufacturing
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Solution Overview
Problem
Current fusion-draw processes for ion-exchangeable glasses result in zirconia inclusions due to the reaction between zircon refractory lining and molten glass, leading to cosmetic defects and strength issues, particularly in thin glass sheets used in electronic devices.
Innovation Solution
A glass composition with a viscosity of 3.5 kPa·s at 35 kpoise, where the breakdown temperature of zircon to form zirconia is higher than the glass formation temperature, preventing zirconia inclusion formation, comprising 61-75 mol% SiO2, 7-15 mol% Al2O3, 0-12 mol% B2O3, 9-21 mol% Na2O, 0-4 mol% K2O, 0-7 mol% MgO, and 0-3 mol% CaO, with a breakdown margin calculated to ensure zirconia-free glass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If zircon refractory lining is used in fusion-draw process, then glass can be manufactured, but zirconia inclusions form in the glass
Solution Approach 1:
The patent modifies the glass composition parameters (specifically adding Al2O3 and adjusting SiO2 content) to change the chemical reactivity between glass and zircon refractory, thereby preventing zirconia inclusion formation while maintaining manufacturability
Solution Approach 2:
Al2O3 acts as an intermediary substance that modifies the interaction between glass and zircon refractory, creating a protective effect that prevents direct reaction and zirconia inclusion formation
2Ease of manufacture
If zircon refractory lining is used in fusion-draw process, then glass can be manufactured, but glass strength is compromised
Solution Approach 1:
Changing the glass composition parameters (Al2O3 content 7-15 mol%, SiO2 content 61-75 mol%) to achieve a breakdown margin that prevents zirconia inclusion formation, thereby maintaining glass strength while enabling manufacturing
3Ease of manufacture
If zircon refractory lining is used in fusion-draw process, then glass can be manufactured, but cosmetic defects occur in thin glass sheets
Solution Approach 1:
The patent adjusts glass composition parameters to achieve a breakdown margin greater than zero, which prevents zirconia inclusion formation and eliminates cosmetic defects in thin glass sheets while maintaining manufacturing 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
The glass is substantially free of fusion line zirconia defects, maintaining strength and cosmetic quality, suitable for electronic device applications, and can be ion-exchanged to produce compressive layers or central tension within the glass.
Implementation Method 1
The glass has a temperature T35kp at which the viscosity of the glass is 3500 Pa·s and a breakdown margin Tmargin=Tbreakdown−T35kp greater than zero, where Tbreakdown is a temperature at which zircon breaks down to form zirconia
Implementation Method 2
The glass is ion-exchangeable to produce a compressive layer on a glass surface or central tension within the glass
Data Source
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AI summary
A glass that is down-drawable and ion exchangeable. The glass has a temperature T35kp at which the viscosity is 35 kilopoise. T35kp is less than the breakdown temperature Tbreakdown of zircon.