Spectral Selective Coating via Atmospheric Sintering and Texturing
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Solution Overview
Problem
Current spectral selective coatings for concentrated solar power (CSP) systems face challenges in achieving high solar absorptance and low thermal emittance at high operating temperatures, with existing materials degrading due to thermal oxidation and being costly to produce, and requiring complex fabrication processes.
Innovation Solution
A method involving sintering metal particles under atmospheric pressure to form a sintered layer with submicron surface roughness on a substrate, which is then textured to enhance spectral selectivity, allowing for increased solar absorptance and reduced thermal emittance, while being cost-effective and stable at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spectral selective coatings (metals, oxides, cermets) are used, then solar absorptance and thermal emittance properties can be achieved, but the coatings degrade due to thermal oxidation at high operating temperatures
Solution Approach 1:
The patent uses a composite structure consisting of a porous底层 layer made from sintered metal or ceramic particles that provides oxidation resistance, combined with a顶层 spectral selective coating layer that provides the desired optical properties. This composite structure allows the底层 to protect against thermal oxidation while the顶层 maintains high solar absorptance and low thermal emittance at elevated temperatures.
2Manufacturing precision
If vacuum fabrication techniques are used to deposit spectral selective coatings, then precise control of layer thickness and coating quality can be achieved, but production costs increase significantly
Solution Approach 1:
The patent replaces complex vacuum deposition mechanical systems with a simpler atmospheric pressure sintering process. Metal or ceramic particles are suspended in a binder and applied to the substrate, then sintered at atmospheric pressure to form the coating layer. This substitution eliminates the need for expensive vacuum equipment while achieving adequate coating density and adhesion through the sintering process.
Solution Approach 2:
The patent changes the processing parameters from vacuum conditions to atmospheric pressure sintering. By controlling the sintering temperature, time, and atmosphere (e.g., using inert or reducing atmospheres), the process achieves proper densification and oxidation control without requiring vacuum equipment, thereby reducing manufacturing costs while maintaining coating quality.
3Reliability
If cermet layers are used to improve spectral selectivity, then solar absorptance increases and thermal emittance decreases, but the performance degrades due to thermal oxidation when exposed to air
Solution Approach 1:
The patent segments the coating into two functional layers: a porous底层 layer made from sintered particles that provides oxidation resistance and structural support, and a顶层 spectral selective layer (which can be cermet-based) that provides the desired optical properties. This segmentation allows each layer to specialize in its primary function without compromising the other.
Solution Approach 2:
The patent creates a composite structure where the porous sintered particle底层 serves as an oxidation-resistant substrate that supports the spectral selective coating. This composite approach allows the use of cermet materials in the顶层 for optimal spectral selectivity while the porous底层 protects against thermal oxidation through its controlled porosity and sintered structure.
4Object-affected harmful factors
If vacuum enclosures are implemented to protect receivers, then thermal oxidation effects are reduced, but design complexity and production cost increase
Solution Approach 1:
The patent extracts the oxidation protection function from the overall system design by incorporating it directly into the coating structure itself. The porous sintered particle底层 provides inherent oxidation resistance, eliminating the need for separate vacuum enclosure systems. This extraction simplifies the overall receiver design while maintaining protection against thermal oxidation.
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 significantly improves the spectral selectivity of CSP systems by increasing solar absorptance and reducing thermal emittance, maintaining stability above 580°C, and reducing production costs by eliminating the need for vacuum environments.
Implementation Method 1
sintering the particles under atmospheric pressure to form a sintered layer on the substrate
Implementation Method 2
texturing the sintered layer to provide a submicron surface roughness height on the sintered layer
Implementation Method 3
increasing its solar absorptance (α) in the solar spectral region (e.g., for wavelengths (λ)≤2 μm)
Implementation Method 4
lowering its thermal emittance (ε) in the infrared (IR) spectral region (e.g., for λ≥2 μm)
Data Source
AI summary
A method of forming a spectral selective coating is disclosed. The method may include providing particles on a substrate, wherein the particles include submicron particles. The method may farther include sintering the particles under atmospheric pressure to form a sintered layer an the substrate and texturing the sintered layer to provide a submicron surface roughness height on the sintered layer.