Coated Ceramic Matrix Composite Seal for Porosity-Limited Sealing
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Solution Overview
Problem
Ceramic matrix composite seals in gas turbine engines have poorer surface qualities due to undulations and residual porosity, which reduce their sealing effectiveness compared to metallic seals.
Innovation Solution
A sealing assembly with a ceramic matrix composite seal coated with a machinable coating, comprising materials like rare earth silicates, yttria-stabilized zirconia, and mullite, applied to both sides and edges of the seal to improve surface smoothness and thermal resistance, with a thickness less than twice that of the seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic matrix composite seals are used, then thermal resistance is improved, but surface quality deteriorates due to undulations and residual porosity
Solution Approach 1:
The patent applies a coating layer composed of different materials (e.g., ceramic materials, metallic materials, or composite materials) onto the ceramic matrix composite seal. This composite structure combines the thermal resistance benefits of the CMC substrate with the surface smoothing benefits of the coating, resolving the contradiction between thermal performance and surface quality.
Solution Approach 2:
The coating is applied selectively to the sealing surfaces of the CMC seal, providing localized surface improvement where it is most needed for sealing contact, while maintaining the bulk thermal properties of the CMC material. This allows surface quality to be enhanced without compromising overall thermal resistance.
2Manufacturing precision
If a coating is applied to the seal, then surface smoothness is improved, but device complexity increases
Solution Approach 1:
The patent specifies that the coating thickness should be less than twice the thickness of the seal itself, and preferably within a specific range (e.g., 0.002 to 0.020 inches). This parameter control ensures the coating provides sufficient surface smoothing without creating excessive complexity or affecting the seal's functional performance.
3Reliability
If the seal thickness is reduced, then sealing efficiency is improved, but structural integrity deteriorates
Solution Approach 1:
The coating layer acts as a reinforcement layer that compensates for the reduced thickness of the CMC seal. The composite structure of the coated seal provides both the thin profile needed for effective sealing and the structural strength required to maintain integrity, resolving the contradiction between sealing efficiency and structural integrity.
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 coated ceramic matrix composite seals exhibit enhanced sealing efficiency, thermal resistance, and wear characteristics, improving their ability to mate effectively with surrounding surfaces and withstand high temperatures.
Implementation Method 1
A seal with a coating. Thermal resistance is enhanced by the coating
Data Source
AI summary
A sealing assembly includes a first component, a second component, and a seal sealing between the first component and the second component. The seal includes a coating. A thickness of the seal is less than about twice the thickness of the coating. A method of fabricating a ceramic matrix composite seal is also disclosed.