Tempered Oven Door Glass Composition for Pyrolysis Heat Resistance
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Solution Overview
Problem
Current pyrolysis oven doors face challenges with internal glass sheets that are prone to deformation and safety concerns due to high thermomechanical stresses, low thermal expansion coefficients, and limited chemical resistance, particularly at high temperatures.
Innovation Solution
A domestic oven door design featuring an internal glass sheet with a specific chemical composition (55-70% SiO2, 12-25% Al2O3, 0-0.5% B2O3, 0-2% Li2O, 0-5% Na2O+K2O, 0-10% MgO, 0-15% CaO, 0-15% SrO, 0-15% BaO, 0-5% ZnO, 0-3% TiO2, 0-4% ZrO2) and multiple glass sheets separated by air gaps, with intermediate sheets enhancing thermal insulation and airflow, and thermally tempered to improve safety and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If borosilicate glass is used for the internal glass sheet, then the glass can withstand high temperatures, but it deforms at high temperatures reducing air gap thickness and degrades thermal insulation
Solution Approach 1:
The patent changes the chemical composition parameters of the glass by eliminating boron oxide and adjusting the ratios of silica, alumina, and other oxides. This parameter change enables the glass to maintain dimensional stability at high temperatures while retaining temperature resistance, resolving the contradiction between temperature resistance and dimensional stability.
Solution Approach 2:
The patent creates a composite glass material by combining multiple oxide components (silica, alumina, magnesia, lime, etc.) in specific proportions. This composite composition provides both high-temperature resistance and dimensional stability, overcoming the limitations of conventional borosilicate glass.
2Stability of the object's composition
If borosilicate glass is used for the internal glass sheet, then the glass has low thermal expansion coefficients, but it is more difficult to achieve large stress differences during thermal tempering
Solution Approach 1:
The patent modifies the chemical composition parameters to achieve an optimal balance between thermal expansion coefficient and glass transition temperature. By eliminating boron oxide and adjusting the composition of other oxides, the glass can maintain low thermal expansion while having a sufficiently high glass transition temperature to enable large stress differences during thermal tempering, thereby improving strength.
3Temperature
If borosilicate glass is used for the internal glass sheet, then the glass withstands high temperatures, but it does not fragment if broken posing safety concerns
Solution Approach 1:
The patent changes the chemical composition to eliminate boron oxide and optimize the ratio of network formers and modifiers. This composition adjustment enables the glass to shatter into small, non-sharp fragments when broken, maintaining temperature resistance while improving safety by eliminating the hazard of large sharp fragments.
4Area of stationary object
If the internal glass sheet has large surface area, then it provides better viewing, but it is subject to higher thermomechanical stresses
Solution Approach 1:
The patent uses a composite glass composition with optimized ratios of silica, alumina, and other oxides to create a material that can withstand high thermomechanical stresses. This composite material enables the glass sheet to have a large surface area for better viewing while maintaining sufficient strength to resist the increased thermomechanical stresses associated with larger areas.
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 solution provides enhanced thermomechanical resistance, hydrolytic resistance, and chemical resistance to acids and bases, while ensuring the glass sheets break into non-sharp fragments upon impact, improving safety and maintaining effective thermal insulation.
Implementation Method 1
the internal glass sheet being thermally tempered
Implementation Method 2
their very low thermal expansion coefficients make it more difficult to achieve large stress differences between the glass core and surface during thermal tempering
Implementation Method 3
said sheets of glass being held together, generally using a metal frame, and separated by an air gap. This configuration makes it possible to limit the temperature at the level of the external sheet of glass
Data Source
Figure 1
AI summary
Invention relates to a domestic oven door (1) comprising an internal glass sheet (3) intended to be the glass sheet closest to the chamber of said oven and an external glass sheet (2), said glass sheets (2, 3) being securely fastened together and being separated by at least one air gap, said internal glass sheet (3) having a chemical composition that comprises the following constituents, by weight content, in the following ranges: SiO2, 55-70%; A12O3, 12-25%; B2O3, 0-0.5%, especially 0%; Li2O, 0-2%; Na2O + K2O, 0-5%, especially 0-1%; MgO, 0-10%; CaO, 0-15%; SrO, 0-15%; BaO, 0-15%; ZnO, 0-5%; RO, 5-25% where RO = MgO + CaO + SrO + BaO + ZnO; TiO2, 0-3%; and ZrO2, 0-4%.