Copper-Tin Alloy Float Bath Suppresses Tin Oxide Specks
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Solution Overview
Problem
The float glass manufacturing process using a tin bath results in defects due to the high vapor pressure of tin oxide, leading to top specks on the glass surface, particularly at high manufacturing temperatures for alkali-free glasses.
Innovation Solution
A tin alloy bath with a predetermined amount of copper (1-40 mass%) is used to reduce the vapor pressure and volatilization of tin, suppressing the formation of tin oxide defects by forming a stable copper-tin alloy that decreases the evaporation of tin and reduces the concentration of copper on the glass surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If pure tin is used for the molten metal bath in float glass manufacturing, then the glass can be formed at relatively low temperature, but the vapor pressure of tin is suppressed low leading to high tin oxide volatilization and top speck defects at high temperatures
Solution Approach 1:
The invention changes the chemical composition parameter of the molten metal bath by adding copper to tin, creating a tin-copper alloy bath. This compositional parameter change fundamentally alters the vapor pressure characteristics and oxidation behavior of the bath, enabling high-temperature processing without excessive tin oxide volatilization and top speck defects.
Solution Approach 2:
The invention uses a composite molten metal system consisting of tin and copper in specific proportions (60-95 wt% Sn, 5-40 wt% Cu). This composite alloy combines the beneficial properties of both metals: tin provides good glass forming characteristics while copper suppresses tin oxide volatilization and reduces top speck formation through modified vapor pressure and oxidation kinetics.
2Stability of the object's composition
If the manufacturing temperature is increased for alkali-free glass, then the glass viscosity is improved, but the vapor pressure of tin oxide increases causing more top specks
Solution Approach 1:
The invention modifies the thermal and chemical parameters of the molten metal bath by introducing copper, which changes the oxidation-reduction equilibrium and vapor pressure characteristics. This allows the system to maintain stable composition at high temperatures while suppressing harmful tin oxide volatilization that would otherwise occur with pure tin baths.
Solution Approach 2:
The invention converts the potential harm of high-temperature processing into a benefit by using copper addition to control the oxidation behavior. The copper modifies the vapor phase chemistry and reduces tin oxide volatility, transforming what would be a harmful high-temperature effect into a controllable and beneficial process condition for producing high-quality alkali-free glass.
3Object-affected harmful factors
If copper is added to the tin bath, then the vapor pressure of tin is reduced and top specks are suppressed, but the composition of the bath becomes more complex
Solution Approach 1:
The invention optimizes the compositional parameters within specific ranges (60-95 wt% Sn, 5-40 wt% Cu) to achieve the desired effect of suppressing tin oxide volatilization while maintaining practical operability. This parameter optimization balances the reduction of top speck defects with the simplicity of bath composition and handling.
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 use of a copper-containing tin alloy bath significantly reduces the number of top specks on the glass, producing high-quality float glass with improved ultraviolet transmittance, surface resistance, and antibacterial properties, while maintaining the desired thickness and flatness.
Implementation Method 1
the vapor pressure of tin can be suppressed low... vapor pressure of tin is high... by using a tin alloy bath in which a predetermined amount of copper is added to molten tin, a vapor pressure can be reduced as compared with a tin bath
Implementation Method 2
molten glass is continuously supplied to a horizontal bath surface of molten tin to form a ribbon-shaped glass
Implementation Method 3
The glass ribbon is then conveyed by conveying rolls (lift-out rolls)... A glass ribbon thus obtained is taken out by traction force of the lift-out rolls
Implementation Method 4
a plurality of lehr rolls are horizontally arranged inside the annealing furnace... the glass ribbon is conveyed to the side of the annealing furnace and is gradually cooled while moving in the annealing furnace
Data Source
AI summary
The present invention provides a tin alloy bath for a float bath, an apparatus for manufacturing a float glass, a method for manufacturing a float glass that can provide a high quality float glass in which defects due to coagulation and falling of a volatile tin component have been suppressed, and a float glass manufactured using those. The above-mentioned tin alloy bath for a float bath is a molten metal bath to be placed in the float bath for supplying molten glass to a liquid surface of the molten metal bath, thereby forming into a glass ribbon, and includes 1 mass % or more of copper with the remainder being unavoidable impurities and tin.