Solar Mirror Coating Structure for Heat-Treated Silver Reflectors
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Solution Overview
Problem
Conventional mirror technologies for concentrated solar power systems face issues with environmental concerns due to wet chemical waste disposal and limitations in processing high-temperature treatments, which affect the longevity and reflectivity of silver-coated mirrors.
Innovation Solution
A reflective article comprising a transparent glass substrate with an inorganic basecoat, a primary reflective coating, an anti-corrosion coating, and a protective coating, allowing for enhanced reflectivity and durability while enabling heat treatment without damaging the silver layer, thus reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If wet chemical process is used to deposit silver coating, then reflectivity is improved, but environmental harm increases due to waste disposal
Solution Approach 1:
The patent replaces the wet chemical deposition process with a physical vapor deposition process (sputtering). This substitution eliminates the need for chemical solutions and waste disposal while achieving comparable or superior silver coating reflectivity. The sputtering process uses physical bombardment with ions to deposit silver atoms onto the glass substrate, thereby resolving the environmental harm issue.
Solution Approach 2:
The patent changes the deposition method from chemical precipitation to physical vapor deposition, fundamentally altering the process parameters. This parameter change transitions the system from a chemical-based process with waste streams to a physical process with minimal environmental impact, while maintaining the desired optical properties of the silver coating.
2Illumination intensity
If silver layer is deposited to achieve high reflectivity, then optical performance is improved, but temperature resistance deteriorates due to damage at high temperatures
Solution Approach 1:
The patent applies a protective coating layer over the silver layer before the glass undergoes heat treatment. This preliminary protective action prevents direct exposure of the silver to high temperatures that would cause damage. The protective layer acts as a barrier, allowing the glass to be heat-treated at temperatures above the silver's damage threshold without compromising the reflective coating.
Solution Approach 2:
The protective coating serves as an intermediary between the silver layer and the high-temperature environment. This intermediary layer absorbs or blocks the thermal stress and chemical attack that would otherwise directly affect the silver, enabling the system to withstand temperatures that would normally damage the reflective coating.
3Reliability
If copper layer is added to protect silver from corrosion, then durability is improved, but environmental harm increases due to wet chemical waste
Solution Approach 1:
The patent replaces the wet chemical copper deposition process with a physical vapor deposition process. This substitution eliminates the environmental harm associated with copper waste disposal while maintaining the protective function. The copper layer is deposited through sputtering, providing corrosion protection without requiring chemical solutions or generating hazardous waste streams.
4Reliability
If multiple coating layers are added to protect silver, then reliability is improved, but device complexity increases
Solution Approach 1:
The protective coating layer performs multiple functions simultaneously: it protects the silver from oxidation and corrosion, acts as a barrier during heat treatment processes, and can contribute to the overall optical properties of the mirror. This multi-functionality reduces the need for separate specialized layers, thereby limiting the increase in complexity while maintaining comprehensive protection.
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 a reflective article with improved durability and reflectivity, enabling heat treatment and reducing environmental concerns by using inorganic coatings that enhance the longevity and performance of solar mirrors.
Implementation Method 1
A basecoat is formed over at least a portion of the second major surface. A primary reflective coating is formed over at least a portion of the basecoat.
Implementation Method 2
A primary reflective coating is formed over at least a portion of the basecoat, wherein the primary reflective coating comprises at least one metal selected from platinum, iridium, osmium, palladium, aluminum, gold, copper, silver
Implementation Method 3
An inorganic protective coating is formed over at least a portion of the primary reflective coating, wherein the protective coating comprises a material selected from silica, alumina, or a mixture of silica and alumina
Implementation Method 4
Mirrors having high reflectance of solar radiation are used for 'concentrated solar thermal power' (CSTP) installations
Data Source
AI summary
A reflective article, such as a solar mirror, includes a highly transparent substrate having a first major surface and a second major surface. At least one reflective coating is formed over at least a portion of one of the surfaces, e.g., the second major surface (or, alternatively, the first major surface). The reflective coating includes at least one metallic layer. An encapsulation structure can be formed over at least a portion of the second reflective coating.