Radar Absorbing Coating Using Carbon Nanotubes
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Solution Overview
Problem
Existing EM field absorbing compositions, particularly those used as radar absorbing coatings, face challenges in achieving effective absorption while maintaining a lightweight structure, as they often require high volumes of magnetic particulates, leading to increased weight and material costs for large surface areas.
Innovation Solution
A composition combining 0.1-3% volume/volume carbon nanotubes with 15-30% volume/volume micron-sized magnetic particulates in a non-conductive binder, allowing for reduced magnetic particulate content and minimal point contact, which reduces weight without compromising radar absorbance, achieved through the use of non-magnetized carbon nanotubes and a suitable binder system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high volumes of magnetic particulates are used in EM field absorbing compositions, then radar absorbance is improved, but weight increases significantly
Solution Approach 1:
The patent combines carbon nanotubes with magnetic particulates to create a composite absorbing composition. The carbon nanotubes form a conductive network that enhances EM field absorption while allowing reduction of magnetic particulate content from conventional levels (50-70 vol%) to lower levels (15-30 vol%), thereby reducing weight while maintaining or improving radar absorbance performance
Solution Approach 2:
The patent changes the physical state and distribution parameters of the absorbing materials by using nanoscale carbon tubes instead of conventional fillers. This parameter change enables the creation of a percolating network at low concentrations that provides effective EM absorption pathways, allowing weight reduction while maintaining performance
2Reliability
If high volumes of magnetic particulates are used in EM field absorbing compositions, then radar absorbance is improved, but material costs increase
Solution Approach 1:
The composite system synergistically combines carbon nanotubes and magnetic particulates where the carbon nanotubes provide conductive pathways for EM field dissipation. This allows the magnetic particulate content to be reduced from conventional high levels (50-70 vol%) to lower levels (15-30 vol%), directly reducing material quantity and cost while maintaining absorption effectiveness
Solution Approach 2:
The carbon nanotubes act as an intermediary that facilitates EM field absorption through their conductive network. This intermediary mechanism allows the system to achieve effective absorption with fewer magnetic particulates, reducing both quantity and cost of the more expensive magnetic material
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
This composition achieves significant weight savings of several hundred kilograms for large surface areas while maintaining effective radar absorbance, controlling permittivity without affecting permeability, and ensuring adherence and flow during application.
Implementation Method 1
an electromagnetic radiation absorbing composition comprising an admixture of carbon nanotubes present in the range of from 0.1 to 3 v/v% dried, magnetic particulates with an average longest dimension of at least 1 micron, present in the range of from 15 to 30%v/v dried, in a non-conductive binder
Implementation Method 2
The addition of the carbon nanotube particulates to a magnetic particulate loaded composition allows a means of providing a very low mass method of controlling the permittivity without affecting the permeability of the composition
Implementation Method 3
magnetic particulates with an average longest dimension of at least 1 micron, present in the range of from 15 to 30%v/v dried
Data Source
AI summary
EM field absorbing compositions, particularly lightweight magnetic and carbon loaded compositions. The composition finds particular use as a radar absorbing coating for structures. There are further provided coated surfaces comprising the composition, methods of absorbing EM radiation, and methods of use of such a composition, such that a surface coated in the composition is capable of absorbing EM radiation. An electromagnetic radiation absorbing composition comprising an admixture of carbon nanotubes present in the range of from 0.1 to 10 v/v% dried, magnetic particulates with an average longest dimension of at least 1 micron,, present in the range of from 1 to 60%v/v dried, in a non-conductive binder..; preferably the iron particulates are present in the range of from 15-30%v/v.