Tin-Controlled Soda-Lime-Silica Glass for High Redox Ratios
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Solution Overview
Problem
Existing methods for making soda-lime-silica glasses with high redox ratios are limited by the type of heating system or furnace used, and can result in silica stone formation and undesirable amber coloration due to the use of carbon to increase redox ratio.
Innovation Solution
A method involving a molten tin bath support during glass forming, with controlled cooling and force application, and the use of tin and/or tin compounds to maintain a high redox ratio regardless of furnace type, while minimizing sulfur and iron presence to prevent amber coloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If carbon is used to increase redox ratio, then redox ratio is improved, but silica stone formation and amber coloration occur
Solution Approach 1:
The patent changes the chemical composition parameters by strictly limiting carbon content to less than 0.003 wt% and sulfur content to less than 0.003 wt%, while controlling iron content between 0.03-3.0 wt%. This parameter control prevents the formation of silica stones and amber coloration while maintaining the desired redox ratio of 0.2-0.6 through alternative means.
Solution Approach 2:
The patent converts the potential harm of carbon and sulfur (which cause silica stone formation and amber coloration) into a benefit by establishing strict upper limits for these elements. By controlling them to extremely low levels, the patent eliminates the harmful effects while maintaining processability and achieving the desired optical properties through controlled iron content and redox ratio.
2Illumination intensity
If iron content is increased to achieve high iron glass, then color intensity is improved, but visible light transmittance decreases
Solution Approach 1:
The patent optimizes the iron content parameter within a specific range of 0.03-3.0 wt% and controls the redox ratio between 0.2-0.6 to achieve the desired balance. By precisely controlling these parameters and limiting carbon and sulfur to less than 0.003 wt% each, the patent achieves both adequate color intensity and high visible light transmittance without the trade-off that would normally exist.
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
Achieves high redox ratio soda-lime-silica glasses with aesthetically desirable blue edge color and high visible light transmittance, avoiding silica stone formation and amber tint, applicable to various glassmaking processes.
Implementation Method 1
The redox ratio of the glass is increased by the addition of tin alone, and/or in combination with other additives, to the glass batch materials and/or molten glass
Implementation Method 2
the tin side of the glass is supported on a molten tin bath during forming of the glass
Implementation Method 3
flowing the molten glass onto a molten tin bath; moving the molten glass on the surface of the molten tin bath, while controllably cooling the glass
Data Source
AI summary
A method of making glass having a basic soda-lime-silica glass portion, and a colorant portion, the colorant portion including total iron as Fe2O3 in the range of at least 0.00 to no more than 0.02 weight percent, a redox ratio in the range of 0.35 to 0.6, and tin metal providing tin in an amount within the range of greater than 0.005 to 5.0 weight percent; the glass product has a tin side and an opposite air side, said tin side of the glass having a higher concentration of tin than the air side, the air side having a uniform concentration of tin from the air side of the glass product towards the tin side of the glass product.