ALD Ceramic Carbon-Carbon Seal Ring for Oxidation and Porosity
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Solution Overview
Problem
Gas turbine engine components, particularly seals, experience wear due to exposure conditions, affecting their lifetime and effectiveness, and existing solutions fail to adequately address oxidation and sub-surface porosity issues at elevated temperatures.
Innovation Solution
A carbon-carbon composite seal ring with a monoaluminum phosphate binder layer and a ceramic layer applied via atomic layer deposition, which fills sub-surface porosity and provides oxidation resistance, is used to enhance the sealing system's durability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon-carbon composite seal rings are used to reduce wear, then wear resistance is improved, but oxidation resistance deteriorates at elevated temperatures
Solution Approach 1:
The patent applies a multi-layer composite coating structure on carbon-carbon composite seal rings, combining binder layers (such as boron phosphate or zinc phosphate) with ceramic layers (such as silicon carbide or silicon nitride). This composite structure provides both wear resistance from the carbon-carbon base material and oxidation resistance from the ceramic outer layer, resolving the contradiction between wear resistance and oxidation resistance at elevated temperatures.
2Ease of manufacture
If conventional coating methods are used, then manufacturing simplicity is maintained, but sub-surface porosity cannot be effectively filled
Solution Approach 1:
The patent replaces conventional mechanical coating methods with atomic layer deposition (ALD), a vapor-phase deposition technique that enables molecular-level control of coating application. ALD allows the coating to conformally deposit and fill sub-surface porosity through vapor diffusion, achieving complete pore filling that mechanical methods cannot accomplish, while maintaining manufacturing feasibility through automated processing.
3Reliability
If the ceramic layer is applied thickly to fill porosity, then porosity filling is improved, but coating stress and delamination risk increase
Solution Approach 1:
The patent segments the coating into multiple thin sub-layers deposited sequentially through ALD, rather than applying a single thick layer. Each sub-layer is deposited at controlled thickness (e.g., 1-10 nanometers per cycle), allowing gradual filling of porosity while minimizing thermal stress accumulation and preventing delamination. The binder layer and ceramic layer are also segmented into separate functional layers, with the binder providing stress management and the ceramic providing oxidation protection.
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 solution significantly improves the oxidation resistance and wear characteristics of the carbon-carbon composite seal rings, extending their lifetime and maintaining sealing effectiveness even at elevated temperatures.
Implementation Method 1
The solution significantly improves the oxidation resistance and wear characteristics of the carbon-carbon composite seal rings
Implementation Method 2
applying a ceramic layer over the binder layer on at least one surface of the seal by atomic layer deposition
Implementation Method 3
The solution significantly improves the oxidation resistance and wear characteristics of the carbon-carbon composite seal rings
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3E
AI summary
A sealing system includes a shaft (50), a rotor (102) configured to rotate with respect to the shaft (50), and a carbon-carbon composite seal ring (100) arranged around the shaft (50) such that it seals against the rotor (102). The carbon-carbon composite seal ring (100) includes a monoaluminum phosphate binder layer disposed on at least one surface of the carbon-carbon composite seal ring (100) and a ceramic layer disposed over the monoaluminum phosphate binder layer on the least one surface of the carbon-carbon composite seal ring (100). A method of manufacturing a seal (100) is also disclosed.