Zircon-Free Refractory Block for Defect-Free Glass Forming
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Solution Overview
Problem
Alkali alumino-silicate glasses used in mechanical applications face issues due to the dissociation of zircon in glass overflow forming blocks, leading to gas bubbles, defects, and reduced block lifetime, as well as contamination of the glass with undesirable elements.
Innovation Solution
A refractory object with a sintered ceramic material containing at least 10% Al2O3, doped with titanium, magnesium, or tantalum oxides, and having low SiO2 content to reduce corrosion and prevent defect formation in glass sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If zircon material is used in the glass overflow forming block, then the block can form glass sheets, but the zircon dissociates at high temperatures causing gas bubbles and defects in the glass
Solution Approach 1:
The patent removes zircon (ZrSiO4) from the refractory material composition entirely, extracting the problematic component that causes dissociation and defect formation. The forming block is replaced with alternative refractory materials that do not contain zircon, thereby eliminating the source of gas bubbles and inclusions in the glass product
Solution Approach 2:
The patent employs composite refractory materials composed of multiple components including alumina, silica, magnesia, and various dopants. These composite materials provide the necessary mechanical strength and chemical stability at high temperatures without the dissociation problems of zircon, maintaining forming capability while preventing defect generation
2Ease of manufacture
If zircon material is used in the glass overflow forming block, then the block can form glass sheets, but the block lifetime is reduced due to erosion
Solution Approach 1:
By removing zircon from the material composition, the patent eliminates the component that erodes and degrades over time at glass forming temperatures. The alternative refractory materials provide sustained structural integrity and resistance to chemical attack, extending the service life of the forming block
Solution Approach 2:
The patent modifies the chemical composition parameters of the refractory material, adjusting the ratios of alumina, silica, magnesia, and dopant concentrations to optimize both forming performance and durability. These parameter changes result in a material that maintains its physical and chemical properties over extended periods at high temperature
3Ease of manufacture
If zircon material is used in the glass overflow forming block, then the block can form glass sheets, but the glass is contaminated with undesirable elements affecting its properties
Solution Approach 1:
The patent extracts and removes zircon from the refractory composition, eliminating the source of zirconium contamination that would otherwise dissolve into the glass and create inclusions and defects. The alternative materials do not introduce harmful contaminants into the glass melt
Solution Approach 2:
The patent converts the harmful effect of zircon dissociation into a benefit by selecting refractory materials that are chemically inert or form protective reaction layers at high temperatures. These materials either resist chemical attack or form stable, non-contaminating surface layers that prevent glass melt contamination while maintaining forming functionality
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 refractory object exhibits lower corrosion rates, maintaining mechanical integrity and preventing defects in glass sheets, allowing for better control over glass composition and extended block lifetime.
Implementation Method 1
The refractory object exhibits lower corrosion rates, maintaining mechanical integrity
Implementation Method 2
preventing defects in glass sheets, allowing for better control over glass composition
Data Source
AI summary
A refractory object can include at least 10 wt % Al2O3. Further, the refractory object may contain less than approximately 6 wt % SiO2 or may include a dopant that includes an oxide of Ti, Mg, Ta, Nb, or any combination thereof. In an embodiment, at least approximately 1% of the Al2O3 in the refractory object can be provided as reactive Al2O3. In another embodiment, the refractory object may have a density of at least approximately 3.55 g/cc, a corrosion rate of no greater than approximately 2.69 mm/year, or any combination of the foregoing. In a particular embodiment, the refractory object can be used to form an Al—Si—Mg glass sheet. In an embodiment, the refractory object may be formed by a process using a compound of Ti, Mg, Ta, Nb, or any combination thereof.