Solar Selective Coating Stack for High-Temperature Corrosion Resistance
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Solution Overview
Problem
Existing solar selective coatings for thermal solar collector systems face challenges in achieving long-term stability at high temperatures and in atmospheric environments, with issues such as corrosion, deterioration, and reduced optical properties over time, especially in CSP plants with vacuum tube systems that lack robustness and longevity.
Innovation Solution
A solar selective coating comprising a metallic adhesion layer with a refractory metal like molybdenum and titanium, configured in an amorphous disordered structure, which acts as a diffusion barrier, corrosion protector, and adhesion enhancer, forming a sandwich construction with absorber and antireflection stacks to maintain optical properties and extend lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multi-layered vacuum coating is used to achieve high solar radiation absorption and low infrared radiation loss, then optical properties are improved, but long-term stability at high temperatures and in atmospheric environments deteriorates due to corrosion and layer deterioration
Solution Approach 1:
A chromium oxide barrier layer is formed on the substrate surface before depositing the solar selective coating layers. This preliminary barrier layer prevents corrosion and deterioration of subsequent layers during high-temperature operation in atmospheric environments, ensuring long-term stability while maintaining optical performance
Solution Approach 2:
The coating system uses composite material structure combining chromium oxide barrier layer with metal nitride absorber layers (TiAlN, TiAlSiN). This composite structure provides both corrosion resistance from the oxide layer and high solar absorption with low thermal emittance from the nitride layers
2Productivity
If vacuum tube systems are used in CSP plants, then solar energy collection is improved, but robustness and longevity deteriorate due to lack of stability in harsh environments
Solution Approach 1:
The chromium oxide barrier layer creates a chemically inert environment at the substrate-coating interface, protecting the metal nitride layers from oxidation and deterioration when exposed to atmospheric conditions at high temperatures, thereby enhancing robustness and longevity
Solution Approach 2:
The barrier layer is deposited beforehand to prevent environmental degradation, allowing the vacuum tube system to maintain its optical and mechanical properties over extended periods in CSP plant operations
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 improved corrosion resistance, reduced thermal emittance, and enhanced absorption of solar radiation, leading to increased durability and efficiency of solar selective coatings in harsh environments, with reduced corrosion rates and maintained optical properties over 25 years.
Implementation Method 1
the adhesion layer can comprise a metallic layer comprising molybdenum and titanium... configured in an amorphous disordered structure, which acts as a diffusion barrier
Implementation Method 2
thermal solar collector systems comprise solar absorbers which convert solar radiation into heat through photo-thermal conversion
Implementation Method 3
The surface layer is generally configured to be spectrally selective absorbing with the aim of absorbing all solar radiation and to avoid loss of absorbed energy as infrared radiation
Data Source
AI summary
An exemplary solar selective coating can be provided to be deposited on a substrate. The exemplary solar selective coating can comprise an adhesion layer, an absorber stack comprising at least one absorber layer, and an antireflection stack which can comprise at least one antireflection layer, e.g., all provided in a sandwich configuration. The sandwich configuration can provide the adhesion layer deposited onto the substrate, the absorber stack deposited on the adhesion layer, and the antireflection stack deposited on the absorber stack. The adhesion layer can comprise a metallic layer comprising molybdenum and titanium.