Ion Exchangeable Alkali Boroaluminosilicate Glass for Float Forming
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Solution Overview
Problem
Conventional damage-resistant glasses lack sufficient impact resistance and efficient ion exchange capabilities, particularly in achieving high Vickers indentation crack initiation loads and maintaining chemical durability while being suitable for float forming processes.
Innovation Solution
Alkali boroaluminosilicate glasses with specific compositions, including SiO2, Al2O3, B2O3, and alkali oxides, are formulated and ion exchanged to create a compressive layer with high Vickers indentation crack initiation loads, enhanced thermal properties, and compatibility with float forming processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional damage-resistant glass compositions are used, then the glass can be formed via float process, but the Vickers indentation crack initiation load is insufficient (below 12 kgf)
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass, specifically adjusting the ratios of SiO2 (65-75 wt%), Al2O3 (5-15 wt%), B2O3 (10-20 wt%), and alkali oxides (5-15 wt%), to achieve both high crack initiation load (>12 kgf) and float processability. This compositional parameter optimization resolves the contradiction between strength and manufacturability.
Solution Approach 2:
The patent creates a composite glass system combining multiple oxide components (silica, alumina, boria, and alkali oxides) in specific proportions. This composite composition provides synergistic effects where each component contributes to different properties: SiO2 for strength, B2O3 for ion exchange capability, and alkali oxides for processability, thereby achieving both high Vickers load resistance and float process compatibility.
2Strength
If the glass composition is optimized for high crack initiation load, then impact resistance improves, but ion exchange capability and chemical durability may be compromised
Solution Approach 1:
The patent creates different functional zones within the glass structure through controlled ion exchange. The surface layer develops high compressive stress for impact resistance, while the bulk composition (with 10-20 wt% B2O3 and 5-15 wt% alkali oxides) maintains ion exchange capability. This local differentiation of properties resolves the contradiction between surface strength and bulk ion exchangeability.
Solution Approach 2:
The patent carefully balances the chemical composition parameters, particularly maintaining B2O3 content at 10-20 wt% and alkali oxides at 5-15 wt%, which provides optimal ion exchange kinetics while supporting high crack initiation load. The specific parameter range ensures both impact resistance and ion exchange capability are achieved simultaneously.
3Productivity
If the glass contains high levels of alkali oxides for fast ion exchange, then ion exchange speed increases, but chemical durability and structural stability decrease
Solution Approach 1:
The patent optimizes the alkali oxide content to a specific range (5-15 wt%) rather than using high concentrations. This parameter control enables sufficient ion exchange speed for practical applications while maintaining chemical durability and structural stability. The balanced composition prevents excessive network disruption that would occur with higher alkali oxide levels.
Solution Approach 2:
The patent creates a composite oxide network where SiO2 (65-75 wt%) and Al2O3 (5-15 wt%) provide structural stability and chemical durability, while B2O3 (10-20 wt%) and controlled alkali oxides (5-15 wt%) enable fast ion exchange. This composite structure resolves the contradiction between ion exchange speed and chemical stability by distributing different functions to different components.
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 resulting glasses exhibit improved damage resistance, achieving Vickers indentation crack initiation loads of at least 12 kgf, along with suitable thermal properties and ion exchange performance, making them suitable for consumer applications and float forming technologies.
Implementation Method 1
when strengthened by ion exchange
Implementation Method 2
capable of being formed into sheets via a float process
Data Source
AI summary
Alkali boroaluminosilicate glasses with high resistance to crack initiation and damage due to sharp impact are provided. The glass compositions have melting and forming temperatures that allow forming the glass into sheets via float-based processes while still allowing for the glass to be efficiently ion exchanged. The glass compositions contain MgO, and when ion exchanged, have a Vickers indentation crack initiation load of at least about 10-15 kgf.