Infrared absorber, method for manufacturing same, blackbody radiation device, and radiative cooling device
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Solution Overview
Problem
Existing infrared absorbers suffer from high reflectance, making them unsuitable for applications requiring low reflectance and high absorptance, such as radiative cooling devices and blackbody radiation devices, due to issues with carbon nanotube breakage and pigment scattering.
Innovation Solution
An infrared absorber is designed with a carbon black absorption layer and a pigment-free resin surface layer featuring a light trapping structure with microscopic projections, reducing hemispherical total reflectance to 0.2% or less in the 5 μm to 15 μm wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aligned carbon nanotubes are used to achieve high emissivity, then infrared absorptance is improved, but structural stability deteriorates due to breakage by physical contact
Solution Approach 1:
The invention changes the material parameters from carbon nanotubes to carbon black particles embedded in resin, and changes the surface structure from smooth to micro-protrusions. This combination achieves high infrared absorptance (emissivity ≥99.5%) while maintaining structural stability and resistance to physical contact damage.
Solution Approach 2:
The invention uses a composite structure consisting of carbon black particles dispersed in a resin matrix, combined with a micro-protrusion surface structure. This composite approach achieves the high infrared absorption properties needed while providing mechanical robustness that carbon nanotubes alone cannot provide.
2Reliability
If pigments are added to the surface layer to enhance absorption, then infrared absorptance is improved, but scattering increases causing infrared rays to leak out
Solution Approach 1:
The invention applies different properties to different layers: the absorption layer contains carbon black for high absorption, while the surface layer uses pigment-free resin to minimize scattering. The micro-protrusions on the surface are specifically designed to trap infrared rays without causing scattering, allowing the system to achieve high absorptance without the harmful scattering effects that would result from adding pigments to the surface layer.
3Ease of manufacture
If a simple flat surface is used, then manufacturing ease is improved, but infrared reflectance remains high
Solution Approach 1:
The invention replaces the flat surface with a micro-protrusion structure, where the curved surfaces of the protrusions help to trap infrared rays through multiple internal reflections. This curved surface geometry significantly reduces infrared reflectance compared to a flat surface, while the protrusions can be formed using conventional molding techniques, maintaining reasonable manufacturing ease.
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 absorber effectively captures and absorbs infrared rays over a wide wavelength range, minimizing reflectance and scattering, enhancing performance in radiative cooling and blackbody radiation applications.
Implementation Method 1
the light trapping structure of the surface layer propagates infrared rays to the inside of the surface layer
Implementation Method 2
the carbon black particles in the absorber absorb infrared rays over a wide wavelength range
Implementation Method 3
the surface layer is substantially pigment-free, thus preventing infrared rays from leaking out due to scattering by pigments near the surface of the surface layer
Data Source
AI summary
Provided are an infrared absorber having extremely low reflectivity in the wavelength band of infrared rays, a method for manufacturing the same, a black-body radiation device, and a radiative cooling device. Provided is an infrared absorber 10 provided with: an absorption layer 11 comprising carbon black and a resin; and, on the absorption layer 11, a surface layer 12 that comprises a resin including essentially no pigment and that has an optical confinement structure 13 in which a plurality of minute projections are formed on the surface thereof, the hemispherical total reflectivity of the infrared absorber 10 in infrared wavelengths of 5-15 μm being 0.2% or less. Further provided are a method for manufacturing the infrared absorber, a black-body radiation device, and a radiative cooling device.