CMC Radome Coating and Attachment for Stable RF Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current silicon nitride radomes for high-speed vehicles are brittle, costly to process, limit design flexibility, and have high RF transmission loss and thermal vulnerability, with permanent bond joints that hinder repair and inspection.
Innovation Solution
A radome formed with a ceramic matrix composite (CMC) shell and a fluid impervious coating, allowing for easier processing, attachment, and RF stability, with fastener attachment for maintenance and thermal expansion accommodation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silicon nitride is used for radome construction, then the radome provides structural protection, but the material becomes brittle and difficult to process
Solution Approach 1:
The patent transitions from monolithic silicon nitride to a composite structure consisting of a CMC shell bonded to a metallic backshell. The CMC provides thermal and RF performance while the metal backshell provides structural strength and facilitates attachment/removal operations, resolving the contradiction between structural protection and ease of manufacture.
2Temperature
If monolithic silicon nitride is used, then the radome provides thermal resistance, but the material becomes vulnerable to thermal shock
Solution Approach 1:
The CMC material combines ceramic thermal resistance with composite toughness, while the metallic backshell provides thermal mass and shock resistance. This composite approach maintains thermal resistance while eliminating the thermal shock vulnerability of monolithic silicon nitride.
3Strength
If permanent bond joints are used to attach the radome, then the attachment is secure, but repair and inspection become impossible
Solution Approach 1:
The radome is segmented into a CMC shell and a metallic backshell that can be independently attached and removed. This segmentation allows the backshell to serve as a removable access cover, enabling repair and inspection while maintaining secure attachment during operation.
Solution Approach 2:
The attachment system transitions from permanent to dynamic/reversible. The metallic backshell can be attached and removed as needed, allowing the system to switch between secure attachment mode and maintenance access mode, resolving the contradiction between attachment security and ease of repair.
4Reliability
If silicon nitride is used, then the radome provides RF transparency, but transmission loss increases at high speeds
Solution Approach 1:
The CMC material maintains RF transparency while exhibiting lower dielectric losses than silicon nitride at high temperatures. When the vehicle travels at high speeds and heats the radome, the CMC composition (e.g., alumina, silica, cordierite) maintains stable RF transmission characteristics, reducing energy loss.
Data Source
AI summary
In a first example, a radome includes a shell including a ceramic matrix composite, the shell forming a first hole at a forward end of the shell and a second hole at an aft end of the shell. The radome also includes a fluid impervious coating on the shell. In a second example, a vehicle includes a main body, the radome, and an attachment assembly that couples the radome to the main body. In a third example, a method includes forming a shell comprising a ceramic matrix composite using a wet layup process, applying a fluid impervious coating onto the shell, and curing the shell and the fluid impervious coating.