Doped Tin Oxide Thin Film Coating for Low-E Glass Durability
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Solution Overview
Problem
Low-E coatings incorporating silver layers face challenges such as limited durability, susceptibility to corrosion, and degradation during heat treatment, tempering, and bending, which affects their infrared reflecting properties and aesthetic appeal.
Innovation Solution
The introduction of an oxidizing chemical additive during pyrolytic deposition of doped tin oxide thin films enhances the optical and infrared reflecting properties, improving durability and resistance to heat treatment, and allowing for online deposition on heated glass ribbons, thus overcoming the limitations of silver-based coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver layers are used in low-E coatings, then high infrared reflectance is achieved, but chemical and mechanical durability deteriorates
Solution Approach 1:
The patent uses a composite structure with multiple thin film layers including metal oxide layers (such as tin oxide, zinc oxide, or indium oxide) combined with dielectric layers. This composite material approach replaces the single silver layer with a multi-layer system that provides both infrared reflectance and enhanced durability, eliminating the corrosion and degradation issues associated with pure silver coatings.
Solution Approach 2:
The patent changes the material parameters by transitioning from metallic silver to metal oxide materials with specific optical and mechanical properties. By adjusting the composition, thickness, and stacking sequence of the metal oxide and dielectric layers, the coating achieves comparable infrared reflectance to silver while providing superior chemical stability and mechanical strength.
2Productivity
If sputter deposited silver layers are used, then high performance solar control is achieved, but production time increases due to offline deposition requirement
Solution Approach 1:
The patent replaces the sputtering deposition process with a pyrolytic deposition process. Pyrolytic deposition allows for online coating application directly on the glass ribbon during the float glass manufacturing process, eliminating the need for separate offline sputtering equipment and operations. This substitution of the deposition mechanism enables continuous production and significantly reduces manufacturing time.
3Reliability
If silver layers are used in low-E coatings, then neutral color appearance is achieved, but aesthetic appeal deteriorates due to oxidation and reaction during heat treatment
Solution Approach 1:
The patent changes the chemical composition parameters by using metal oxides (tin oxide, zinc oxide, indium oxide) instead of metallic silver. These metal oxide materials have inherent resistance to oxidation and chemical reactions, maintaining their optical properties and neutral appearance even after exposure to high temperatures during heat treatment processes. The material parameter change from metal to metal oxide eliminates the aesthetic degradation problem.
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 method results in low-E thin film optical stacks with improved infrared reflecting properties, increased durability, and reduced production time, making them competitive with silver-based coatings in terms of performance and cost.
Implementation Method 1
pyrolytic deposition of doped tin oxide thin films
Implementation Method 2
pyrolytic deposition
Implementation Method 3
introduction of an oxidizing chemical additive during pyrolytic deposition
Implementation Method 4
reflecting and blocking emission of infrared (IR) radiation
Implementation Method 5
permit the passage of visible light
Data Source
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AI summary
The present invention provides low-E thin film optical stacks with improved optical and infrared reflecting properties and methods of making the same. More specifically, the present invention provides for a metal oxide thin film coating that exhibits lower emissivity values than its predecessor due to the inclusion of an oxidizer in the metal oxide deposition process, such as a strong acid such as nitric acid. The present invention also provides for a method that increases the coating efficiencies of the thin films described herein.