Alkali-free Glass Sheet Composition for High Rigidity
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Solution Overview
Problem
Glass sheets for organic EL devices and magnetic recording media face challenges in maintaining high Young's modulus and strain point while maintaining productivity and cost-effectiveness, as increasing these properties leads to decreased devitrification resistance and increased manufacturing costs, and they are prone to bending and deformation during high-speed rotation.
Innovation Solution
An alkali-free glass sheet with a specific composition range of SiO2, Al2O3, B2O3, Li2O+Na2O+K2O, MgO, CaO, SrO, and BaO, with controlled ratios, that achieves a Young's modulus of 83 GPa or more, a strain point of 730°C or more, and a liquidus temperature of 1350°C or less, allowing for high thermal stability and resistance to deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the Young's modulus and strain point of the glass sheet are increased to reduce deflection and thermal shrinkage, then the thermal stability and rigidity are improved, but the devitrification resistance decreases and the liquidus viscosity increases
Solution Approach 1:
The patent applies parameter changes by precisely adjusting the chemical composition parameters of the glass sheet. Specifically, it controls the content of SiO2 (64-72%), Al2O3 (12-16%), MgO (6-12%), CaO (3-9%), and other oxides within specific ranges to achieve the optimal balance between Young's modulus (83 GPa or more) and devitrification resistance. This compositional parameter optimization allows the glass to maintain high rigidity while preventing crystallization during heat treatment.
Solution Approach 2:
The patent employs composite materials by combining multiple oxide components in specific proportions. The glass sheet is formed as a composite system containing SiO2, Al2O3, MgO, CaO, B2O3, and other oxides, where each component contributes specific properties. This composite approach enables the simultaneous achievement of high Young's modulus, high strain point (730°C or more), and maintained devitrification resistance, resolving the contradiction between rigidity and crystallization resistance.
2Measurement precision
If the glass sheet is increased in size and reduced in thickness for high-resolution displays, then the display resolution is improved, but the glass sheet easily bends and manufacturing cost increases
Solution Approach 1:
The patent applies parameter changes by modifying the physical parameters of the glass sheet, specifically increasing the Young's modulus to 83 GPa or more and the strain point to 730°C or more. These parameter changes enhance the glass sheet's rigidity and thermal stability, enabling it to withstand bending during handling and manufacturing while maintaining the required thin thickness (0.5mm or less) and large size for high-resolution displays.
3Area of stationary object
If the glass sheet is increased in size and reduced in thickness, then the display size and resolution are improved, but the glass sheet is prone to bending and deformation during high-speed rotation
Solution Approach 1:
The patent applies parameter changes by increasing the Young's modulus to 83 GPa or more, which directly enhances the glass sheet's resistance to bending. This parameter change enables large-sized glass sheets (for high-resolution displays) to maintain their shape during high-speed rotation in magnetic recording media, preventing the bending and deformation that would otherwise occur.
4Reliability
If the liquidus viscosity of the glass sheet is increased to improve devitrification resistance, then the crystallization resistance is improved, but the meltability decreases and the forming temperature increases
Solution Approach 1:
The patent applies parameter changes by optimizing the chemical composition parameters, specifically controlling SiO2 (64-72%), Al2O3 (12-16%), MgO (6-12%), and CaO (3-9%) within precise ranges. This compositional optimization achieves the desired liquidus viscosity for devitrification resistance while maintaining acceptable meltability and forming temperature, resolving the contradiction between crystallization resistance and ease of manufacturing.
Data Source
AI summary
An alkali-free glass sheet of the present invention contains, as a glass composition, in mol %, from 64 to 72% of SiO2, from 12 to 16% of Al2O3, from 0 to 3% of B2O3, from 0 to 0.5% of Li2O+Na2O+K2O, from 6 to 12% of MgO, from 3 to less than 9% of CaO, from 0 to 2% of SrO, and from 0 to 1% of BaO, and the alkali-free glass sheet has a mol % ratio SrO/CaO of from 0 to 0.2, and a mol % ratio (MgO+CaO+SrO+BaO)×CaO/(SiO2×MgO) of from 0 to 0.3.