Solar selective coating for mid-high temperature solar thermal applications
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Solution Overview
Problem
Current solar selective coatings for metal substrates face challenges in simplifying production techniques without compromising stability and efficiency, particularly in achieving high absorptance and emittance while maintaining durability and resistance to corrosion across a range of temperatures.
Innovation Solution
A solar selective coating comprising AlTiN or AlTiSiN layers deposited via reactive magnetron sputtering on stainless steel or copper substrates, with specific atomic compositions and layer thicknesses, to achieve high thermal stability and solar selectivity, and a process involving a double layer configuration of absorber and semi-absorber layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional multilayer solar selective coatings are used, then absorptance and emittance efficiency can be achieved, but the production process becomes complex and costly
Solution Approach 1:
The patent combines multiple functional layers (absorber layer, semi-absorber layer, and protective layer) into an integrated coating system where AlTiN and AlTiSiN layers serve both optical and protective functions simultaneously, reducing the need for separate complex layers while maintaining high absorptance (>0.97) and emittance efficiency
Solution Approach 2:
The patent uses composite AlTiN-AlTiSiN coating structures where different material compositions are combined to achieve optimized optical properties and thermal stability. The specific atomic percentage ranges (Al: 25-40%, Ti: 15-40%, N: 20-45%, Si: 0.5-5%) create a composite material system that simplifies production while maintaining manufacturing precision for solar thermal applications
2Reliability
If coating layers are optimized for high thermal stability, then durability improves, but production complexity increases
Solution Approach 1:
The patent optimizes specific compositional parameters within defined ranges (Al: 25-40 at.%, Ti: 15-40 at.%, N: 20-45 at.%, Si: 0.5-5 at.%) to achieve high thermal stability up to 900°C in vacuum and 650°C in air. By controlling these parameters rather than adding complex structural layers, the patent maintains durability while avoiding excessive production complexity
Solution Approach 2:
The patent applies different material compositions to different layers (absorber layer vs. semi-absorber layer) with specific AlTiN and AlTiSiN formulations optimized for their respective functions. The absorber layer uses specific composition ranges for maximum solar absorption, while the semi-absorber layer uses optimized compositions for thermal stability and protection, achieving localized optimization without overall system complexity
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 coatings with absorptance greater than 0.97, thermal stability up to 900°C in vacuum and 650°C in air, and enhanced durability and corrosion resistance, while simplifying the production process.
Implementation Method 1
A solar selective coating comprising AlTiN or AlTiSiN layers deposited via reactive magnetron sputtering on stainless steel or copper substrates
Data Source
AI summary
The present invention relates to a solar selective coating for a metal substrate comprising at least one absorber layer and at least one semi-absorber layer selected from the structures of AlTiN and AlTiSiN. In preferred embodiments, the solar selective coating according to the present invention is a double layer coating with AlTiN—AlTiN or AlTiSiN—AlTiSiN formation. The process for producing the coating includes a step of treatment of the metal substrate with a reactive magnetron sputtering system.