Alkali-free glass composition for thin display substrates
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Solution Overview
Problem
Conventional alkali-free glass with high specific elastic modulus has issues such as high density, poor clarity, low thermal expansion coefficient, and poor solubility, making it unsuitable for thin glass substrates in large displays.
Innovation Solution
An alkali-free glass composition comprising SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO, optimized to achieve a high specific elastic modulus, suitable strain point, low density, and appropriate thermal expansion coefficient, with specific ranges for each component to enhance clarity and solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional alkali-free glass with high specific elastic modulus is used, then deflection and warpage are suppressed, but density increases and clarity deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition ratios of multiple oxides (SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO) to achieve a specific balance that simultaneously improves specific elastic modulus and clarity. The compositional parameters are optimized within defined ranges to resolve the contradiction between strength and optical properties.
Solution Approach 2:
The patent uses composite materials by combining multiple oxide components in specific proportions to create a glass composition that achieves both high specific elastic modulus and good clarity. The composite nature of the glass, formed by integrating different oxide materials, allows simultaneous optimization of mechanical and optical properties.
2Weight of moving object
If glass plate thickness is reduced to decrease display weight, then weight decreases, but deflection due to own weight increases
Solution Approach 1:
The patent changes the material parameters by optimizing the glass composition to achieve a high specific elastic modulus. This allows the glass to maintain sufficient mechanical strength and deflection resistance even when the plate thickness is reduced, thereby enabling weight reduction without sacrificing structural integrity.
Solution Approach 2:
The patent applies preliminary anti-action by pre-optimizing the glass composition to have high specific elastic modulus before the glass plate is manufactured. This preliminary optimization counteracts the inherent weakness of thin plates, preventing excessive deflection due to own weight even at reduced thickness.
3Stability of the object's composition
If strain point is increased to reduce deformation at high temperature, then thermal stability improves, but density increases and solubility deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the compositional ratios of multiple oxides to achieve a strain point within the optimal range of 690-710°C. This compositional optimization simultaneously maintains good solubility and thermal stability, resolving the contradiction between these two properties.
Data Source
AI summary
To provide an alkali-free glass having a high specific elastic modulus, a suitable strain point, a low density, a not too low thermal expansion coefficient, a good clarity and a good solubility.An alkali-free glass, which comprises, as represented by mol % based on oxides, SiO2: 62 to 70%, Al2O3: 11 to 14%, B2O3: 3 to 6%, MgO: 7 to 10%, CaO: 3 to 9%, SrO: 1 to 5% and BaO: 0 to 1%, wherein [SiO2]+0.7[Al2O3]+1.2[B2O3]+0.5[MgO]+0.4[CaO]−0.25[SrO]−0.88[BaO] is at least 85, [SiO2]+0.45[Al2O3]+0.21[B2O3]−0.042[MgO]+0.042[CaO]+0.15[SrO]+0.38[BaO] is from 72 to 75, 0.4[SiO2]+0.4[Al2O3]+0.25[B2O3]−0.7[MgO]−0.88[CaO]−1.4[SrO]−1.7[BaO] is at most 19, the specific modulus is at least 32 MN·m/kg, the strain point is from 690 to 710° C., the density is at most 2.54 g/cm3, the average thermal expansion coefficient at from 50 to 350° C. is at least 35×10−7/° C., and the temperature T2 at which the glass viscosity reaches 102 dPa·s is from 1,610 to 1,680° C.