Multi-layer Coated Glass Substrate Infrared Reflectivity
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Solution Overview
Problem
Current heat reflective coatings on glass substrates are limited in their ability to effectively reflect infrared wavelengths between 1000 nm to 5000 nm and 5000 nm to 21,000 nm, and they degrade quickly in heated applications due to mismatched expansion characteristics and thickness constraints.
Innovation Solution
A multi-layered coating system on glass substrates, comprising metal oxides with adjustable thickness, chemical composition, and refractive index, applied via pyrolytic deposition to enhance reflectivity across the desired wavelength ranges, ensuring durability and compatibility with high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single layer pyrolytic coatings are applied to maximize heat reflection, then reflectivity in certain wavelength ranges improves, but the coating thickness must be increased which causes mismatch in expansion characteristics with the glass substrate leading to degradation
Solution Approach 1:
The patent divides the coating into multiple layers (typically 3-7 layers) with alternating high and low refractive indices. Each layer has optimized thickness of 50-200 nm, well below the 350 nm threshold that causes expansion mismatch. This segmentation allows the coating to achieve high reflectivity through optical interference effects rather than relying on excessive thickness, thereby maintaining durability while improving heat reflection across multiple wavelength ranges simultaneously.
2Reliability
If coating thickness is increased to improve heat reflection in single layer coatings, then reflectivity improves, but durability degrades due to expansion mismatch between coating and substrate
Solution Approach 1:
The patent employs composite multi-layer structures combining materials with different refractive indices (e.g., TiO2/SiO2, ZnO/SiO2, SnO2/SiO2). This composite approach enables optimized optical interference patterns that enhance heat reflection efficiency across specific wavelength ranges (visible 400-700 nm, near-IR 700-2500 nm, mid-IR 2500-5000 nm) while keeping each layer thin (50-200 nm) to prevent expansion mismatch and maintain coating durability.
3Loss of energy
If multi-layered coatings are used to optimize reflectivity across multiple wavelength ranges, then heat reflection performance improves, but device complexity increases
Solution Approach 1:
The patent systematically varies key parameters including refractive index (alternating high/low), layer thickness (50-200 nm each), and number of layers (3-7 layers) to optimize reflectivity across different wavelength ranges. By controlling these parameters, the multi-layer coating achieves superior heat reflection performance in visible (400-700 nm), near-IR (700-2500 nm), and mid-IR (2500-5000 nm) ranges while maintaining manageable structural complexity through standardized layer configurations and thickness ranges.
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 multi-layered coating system significantly improves reflectivity across the 700 nm to 21,000 nm range, including both visible and infrared wavelengths, while maintaining durability and preventing color reflection, thus addressing the limitations of existing coatings.
Implementation Method 1
Each of the plurality of layers exhibits reflection of infrared light... the number of layers used can address the range from 1000 nm to 5000 nm and allows for optimization in the range of 5000 nm to 21,000 nm
Implementation Method 2
The coating layers of the present disclosure are applied via pyrolytic deposition
Data Source
AI summary
The present disclosure provides a coated glass or glass-ceramic substrate, wherein at least two coating layers are applied to each side of the substrate. Each of the coating layers comprises one or more metal oxides, and optionally a dopant. The dopant can be a halogen or post transition metal. The coated substrate can have two coating layers on each side, three coating layers on each side, or two coating layers on one side and three coating layers on the other side. The properties of each of the coating layers are adjusted so that the coated substrate can reflect infrared light in targeted wavelength ranges. The properties that can be adjusted include the number of coating layers, the coating layer thickness, the coating layer composition, the index of refraction of each coating layer, and the location of each coating layer according to their index of refraction.