Environmental Barrier Coating with Porous Transition Layer
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Solution Overview
Problem
High-temperature materials used in applications like gas turbine engines face significant degradation due to reactive species such as water vapor, leading to surface recession and mass loss, and existing environmental barrier coatings (EBCs) can suffer from spallation caused by gaseous reaction products, limiting their utility and integrity.
Innovation Solution
The implementation of a porous transition layer between the substrate and the sealing layer, along with strategically placed openings to allow gaseous species to escape, and a hermetic sealing layer that can flow to seal defects, enhances the protection of the substrate by preventing detrimental species from reaching the surface and mitigating gas bubble buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional EBC systems are applied to silicon-bearing materials, then protection against water vapor degradation is provided, but spallation occurs due to gaseous reaction products building up under the coating
Solution Approach 1:
The patent introduces a porous transition layer between the substrate and the hermetic sealing layer. This porous layer allows gaseous reaction products to escape through its pore structure, preventing pressure buildup that would cause spallation. The porous material serves as a pressure relief pathway while still providing environmental protection.
Solution Approach 2:
The porous transition layer acts as an intermediary between the substrate and the hermetic sealing layer. It mediates the conflict between needing a hermetic barrier and allowing gas escape by providing a transitional zone that facilitates controlled gas release while maintaining overall coating integrity.
2Object-affected harmful factors
If a hermetic sealing layer is applied to prevent contact between environment and substrate, then protection against reactive species is improved, but gaseous reaction products cannot escape causing spallation
Solution Approach 1:
The hermetic sealing layer is applied over a porous transition layer that allows gas escape. The porous structure provides pathways for gaseous reaction products to leave the system, preventing bubble buildup while the hermetic layer continues to block environmental reactive species from reaching the substrate.
Solution Approach 2:
The coating system is segmented into multiple functional layers: a porous transition layer for gas escape and a hermetic sealing layer for environmental protection. This segmentation allows each layer to perform its specific function without compromising the other, resolving the contradiction between hermeticity and gas permeability.
3Temperature
If silicon-bearing materials are used for high-temperature applications, then attractive high-temperature properties are achieved, but significant surface recession and mass loss occur due to water vapor reaction
Solution Approach 1:
The EBC system acts as an intermediary barrier between the water vapor environment and the silicon-bearing substrate. The coating layers, particularly the hermetic sealing layer, prevent direct contact between water vapor and the substrate, thereby eliminating the chemical reaction that causes surface recession and mass loss while allowing the substrate to maintain its high-temperature properties.
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 configuration significantly reduces spallation and enhances the protective capabilities of EBCs, allowing for higher temperature applications while maintaining the integrity of the coating and substrate, and can be economically and reproducibly produced.
Implementation Method 1
a hermetic sealing layer that can flow to seal defects, enhances the protection of the substrate by preventing detrimental species from reaching the surface
Implementation Method 2
The implementation of a porous transition layer between the substrate and the sealing layer, along with strategically placed openings to allow gaseous species to escape
Implementation Method 3
a hermetic sealing layer that can flow to seal defects
Data Source
Figure 1
Figure 2
AI summary
An article includes a substrate, a substantially hermetic sealing layer disposed on the substrate, and a porous transition layer disposed on the substrate between the sealing layer and the substrate. The article also includes one or more openings extending through the substrate to the porous transition layer.