Paint with low light reflectivity
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Solution Overview
Problem
Current low reflectivity coatings, such as those using carbon nanotubes, are expensive, easily damaged, and pose safety hazards due to their physical nature, while existing alternatives fail to achieve the required low total hemispherical reflectance and are not suitable for industrial and scientific applications where low reflectivity is crucial.
Innovation Solution
A method of coating a substrate with a suspension of dye and binder, where the dye to binder ratio is greater than 40 wt%, applied as a low-density coating with a density of up to 0.75 g/cm³, and optionally subjected to plasma etching to further reduce reflectivity, creating a hydrophobic layer for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If carbon nanotubes are used to create low reflectivity coating, then optical absorption is improved, but cost increases and mechanical durability deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of the coating by using amorphous carbon deposited at low energy (electron beam or ion beam) with controlled ion-to-neutral ratios. This produces a porous, low-density carbon structure with superior optical absorption properties while being more cost-effective and mechanically durable than carbon nanotube coatings.
Solution Approach 2:
The patent creates a coating that copies the optical absorption function of carbon nanotubes but uses a different material structure (amorphous carbon with controlled porosity) that is more practical for industrial applications, eliminating the need for complex nanotube synthesis while achieving comparable or superior performance.
2Loss of energy
If carbon nanotubes are used for low reflectivity coating, then optical absorption is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent changes the deposition parameters by using low energy electron or ion beams with controlled ion-to-neutral ratios, creating an amorphous carbon structure with optimized porosity and density that provides both superior optical absorption and enhanced mechanical durability compared to carbon nanotube coatings.
3Loss of energy
If carbon nanotubes are used in coating, then optical absorption is improved, but safety hazards increase
Solution Approach 1:
The patent replaces the hazardous carbon nanotube material with a safer amorphous carbon coating that can be deposited directly onto substrates. This eliminates the need to handle and process carbon nanotube powders, removing the associated health and safety risks while maintaining the optical absorption function.
4Ease of manufacture
If existing alternative coatings are used, then cost is reduced, but optical absorption deteriorates
Solution Approach 1:
The patent achieves superior optical absorption at lower cost by changing the deposition methodology to low energy electron or ion beam techniques with controlled ion-to-neutral ratios. This produces a porous amorphous carbon structure that outperforms conventional coatings while being more economical than carbon nanotube production.
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 achieves a total hemispherical reflectance of 1% or less in the visible spectrum, providing a cost-effective, damage-resistant, and non-hazardous coating suitable for sensitive applications, with improved optical absorption and scatter properties.
Implementation Method 1
depositing a coating of amorphous carbon onto a substrate by a low energy electron beam or ion beam
Implementation Method 2
The coating has a density of less than 1.0 g/cm³, preferably from 0.1 to 0.75 g/cm³, which contributes to its light scattering and absorption properties
Implementation Method 3
capable of substantially uniform optical absorption over a wide area
Data Source
AI summary
A method of coating a substrate includes the steps of: (i) providing a suspension of dye and a binder in a solvent, wherein the ratio of dye to binder is greater than 40 wt % and the dye is uniformly dispersed in the solvent; (ii) spray-coating the suspension onto the substrate with the majority of the solvent evaporating during the spray coating step to result in a coating of dye and binder on the substrate having a density of up to 0.75 gcm-3; and (iii) continuing step (ii) until the coating thickness is at least 30 micrometres; wherein the dye does not include any carbon nanotubes.