Composite Coating Layer for CMC Substrates Resolving Thermal Mismatch
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Solution Overview
Problem
High-temperature mechanical systems, such as gas turbine engines, face challenges with coatings on ceramic matrix composite (CMC) substrates due to thermal expansion mismatch and susceptibility to CMAS (Calcium-Magnesium-Alumino-Silicate) attack, leading to reduced component lifespan and increased maintenance costs.
Innovation Solution
A composite coating layer is developed using a rare-earth disilicate as the first coating material and a rare-earth monosilicate, CMAS-resistant material, or high-temperature dislocating material as the second coating material, where the second material forms a substantially continuous phase, encapsulating the first material, to reduce thermal expansion mismatch and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied to protect CMC substrate from thermal and environmental exposure, then the substrate is protected from radiant heat and environmental elements, but thermal expansion mismatch between coating and substrate causes spallation and degradation
Solution Approach 1:
The patent applies parameter changes by carefully selecting and controlling the composition ratios of rare-earth disilicate and rare-earth monosilicate in the coating layer. By adjusting these compositional parameters, the coating's thermal expansion coefficient is tuned to match that of the CMC substrate, thereby eliminating thermal expansion mismatch and preventing spallation during thermal cycling.
Solution Approach 2:
The patent employs composite materials by creating a coating layer that combines rare-earth disilicate and rare-earth monosilicate in a specific composite structure. This composite coating leverages the complementary properties of both materials: rare-earth disilicate provides thermal stability while rare-earth monosilicate provides CMAS resistance, and their combination achieves matched thermal expansion with the substrate.
2Reliability
If a coating layer is applied to protect CMC substrate, then protection from environmental elements is improved, but susceptibility to CMAS attack reduces component lifespan
Solution Approach 1:
The patent uses composite materials by formulating a coating layer with a specific combination of rare-earth disilicate and rare-earth monosilicate. The rare-earth monosilicate component provides exceptional resistance to CMAS (calcium magnesium alumino silicate) attack, while the rare-earth disilicate contributes to overall coating stability. This composite structure simultaneously achieves environmental protection and extended component lifespan in high-temperature applications.
Solution Approach 2:
The patent applies parameter changes by optimizing the compositional ratio and microstructure of the coating materials. By controlling the concentration and distribution of rare-earth monosilicate within the coating layer, the resistance to CMAS infiltration is enhanced, thereby preventing degradation and extending the operational life of the CMC component in harsh environments.
3Reliability
If multiple coating materials are used to provide different functions, then protection against thermal expansion mismatch and CMAS attack is improved, but coating structure complexity increases
Solution Approach 1:
The patent applies merging by integrating multiple functional requirements into a single coating layer rather than using separate layers. The coating simultaneously incorporates rare-earth disilicate for thermal expansion matching and rare-earth monosilicate for CMAS resistance, combining protection against both thermal mismatch and chemical attack in one unified structure, thereby simplifying the overall coating system.
Solution Approach 2:
The patent uses composite materials to achieve multi-functionality in a single coating layer. By creating a composite of rare-earth disilicate and rare-earth monosilicate with controlled microstructure, the coating delivers both thermal expansion compatibility and CMAS resistance simultaneously, avoiding the need for complex multi-layer structures and reducing manufacturing complexity.
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 composite coating layer reduces the risk of spallation and degradation due to thermal expansion mismatch and CMAS attack, extending the lifespan of high-temperature mechanical system components while minimizing maintenance costs by integrating multiple functions into a single layer.
Implementation Method 1
introducing, to a heated plume of a thermal spray gun, a composite coating feedstock and directing, using the heated plume, the composite feedstock to a surface of a substrate including a ceramic matrix composite (CMC) to deposit a composite coating layer
Data Source
AI summary
An article may include a substrate including a ceramic matrix composite (CMC); a composite coating layer including a first coating material that includes a rare-earth disilicate and a second coating material that includes at least one of a rare-earth monosilicate, a CMAS-resistant material, or a high-temperature dislocating material, where the second coating material forms a substantially continuous phase in the composite coating layer.