Alumina Refractory Grain Control for Glass Overflow Blocks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Alkali alumino-silicate glasses formed using zircon-based glass overflow forming blocks face issues with gas bubble formation, grain defects, and contamination due to ZrO2 nodules, leading to reduced refractory lifetime and glass property degradation.
Innovation Solution
Development of an alumina-based refractory object with specific grain size and aspect ratio control, incorporating dopants like Ta2O5 and sintering agents to create a stable interface, reducing porosity and creep rate, and forming a Mg-Al oxide layer to act as a diffusion barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zircon-based glass overflow forming blocks are used, then glass formation is achieved, but gas bubbles and ZrO2 solid nodules contaminate the glass and reduce refractory lifetime
Solution Approach 1:
The patent removes zircon material from the refractory composition entirely, replacing it with alumina-based materials. This extraction eliminates the source of ZrO2 nodules and gas bubbles that contaminate the glass, while maintaining the refractory's structural integrity and functionality through alternative material selection.
Solution Approach 2:
The patent employs composite refractory materials combining alumina with specific additives (CaO, MgO, SiO2, Al2O3) to create a multi-phase structure that resists glass contamination. This composite approach provides both mechanical strength and chemical stability, preventing the formation of harmful ZrO2 nodules while extending refractory service life.
2Ease of manufacture
If zircon material is used in glass overflow forming block, then glass can be formed, but zircon dissociates into ZrO2 and SiO2 causing erosion and contamination
Solution Approach 1:
The patent fundamentally changes the chemical composition parameters of the refractory material, transitioning from zircon (ZrSiO4) to alumina-based compositions with controlled amounts of CaO, MgO, SiO2, and Al2O3. This parameter change eliminates the dissociation reaction that produces harmful ZrO2 nodules while maintaining the refractory's ability to support glass formation.
Solution Approach 2:
The patent converts the potential harm of material dissociation into a benefit by selecting alumina-based materials that undergo stable phase transitions at high temperatures. The controlled formation of spinel phases and other stable compounds actually enhances the refractory's resistance to glass erosion while preventing contamination.
3Productivity
If high SiO2 content is present in zircon material, then glass formation is facilitated, but gas bubbles form as SiO2 dissolves into the glass
Solution Approach 1:
The patent introduces MgO and CaO as intermediary substances that act as buffers between the refractory structure and the glass melt. These intermediaries form stable spinel and calcium silicate phases that control silicon release, preventing sudden SiO2 dissolution that would generate gas bubbles while maintaining steady glass formation.
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 alumina-based refractory objects exhibit improved stability, reduced defects, and extended lifespan, maintaining glass quality and refractory integrity during the glass production process.
Implementation Method 1
an amount of a dopant sufficient to keep an averaged grain size of the alumina-containing grains in the sintered ceramic material from increasing more than 500% during a sintering operation
Implementation Method 2
forming a Mg-Al oxide layer to act as a diffusion barrier
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A refractory object can include at least 10 wt% Al2O3. In an embodiment, the refractory object can further include a dopant including an oxide of a rare earth element, Ta, Nb, Hf, or any combination thereof. In another embodiment, the refractory object may have a property such that the averaged grain size does not increase more than 500% during sintering, an aspect ratio less than approximately 4.0, a creep rate less than approximately 1.0x10-5 µm/(µm x hr), or any combination thereof. In a particular embodiment, the refractory object can be in the form of a refractory block or a glass overflow forming block. The glass overflow forming block can be useful in forming an Al-Si-Mg glass sheet. In a particular embodiment, a layer including Mg-Al oxide can initially form along exposed surfaces of the glass overflow forming block when forming the Al-Si-Mg glass sheet.