Coated CMC Seal Assembly for Smooth High-Temperature Sealing
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Solution Overview
Problem
Ceramic matrix composite seals in gas turbine engines have poorer surface qualities due to undulations, residual porosity, and inherent roughness, which reduce sealing effectiveness.
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, with a thickness less than twice the seal thickness, to improve surface smoothness and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a ceramic matrix composite seal is used, then high temperature resistance is improved, but surface quality deteriorates due to undulations, residual porosity, and inherent roughness
Solution Approach 1:
The seal combines ceramic matrix composite material for high temperature resistance with a separate coating layer for surface quality. This composite structure allows each material to perform its specialized function - the CMC provides thermal resistance while the coating provides a smooth sealing surface.
Solution Approach 2:
The coating acts as an intermediary layer between the ceramic matrix composite seal and the sealing surface. It mediates the contradiction by providing a smooth interface for sealing while allowing the underlying CMC to maintain its high temperature resistance properties.
2Manufacturing precision
If a thick coating is applied to improve surface smoothness, then sealing effectiveness is improved, but the overall seal thickness increases beyond geometric requirements
Solution Approach 1:
The coating thickness is precisely controlled within a specific range (0.005-0.070 inches) to achieve the necessary surface smoothness for effective sealing while maintaining the overall seal thickness within geometric requirements. This parameter optimization resolves the contradiction between surface quality and dimensional constraints.
3Length of moving object
If the seal thickness is reduced to meet geometric requirements, then space constraints are satisfied, but the seal may lack sufficient structural integrity
Solution Approach 1:
The composite structure of CMC seal with coating layer provides enhanced strength-to-thickness ratio. The combination of materials delivers sufficient structural integrity even at reduced thicknesses, satisfying both geometric requirements and mechanical strength needs.
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 seal enhances sealing efficiency, wear characteristics, and thermal resistance, providing a better interface with surrounding surfaces while maintaining flexibility and meeting geometric requirements.
Implementation Method 1
improve surface smoothness and thermal resistance
Data Source
Figure 1~2
AI summary
A sealing assembly includes a first component (102), a second component (104), and a seal (100) sealing between the first component (102) and the second component (104). The seal (100) includes a coating (200). A thickness (Tseal) of the seal (100) is less than about twice the thickness (T) of the coating (200). A method of fabricating a ceramic matrix composite seal (100) is also disclosed.