Thermal Barrier Coating CMAS Infiltration Prevention
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Solution Overview
Problem
Thermal barrier coatings in high-temperature applications, such as turbine components, are susceptible to damage from environmental contaminants like CMAS (calcium-magnesium-aluminum-silicon-oxide) deposits, which can infiltrate and degrade the coatings, leading to premature failure and increased maintenance costs.
Innovation Solution
A coating system with elongated surface-connected voids filled with a protective agent that chemically reacts with liquid CMAS to form a solid crystalline product with a melting temperature greater than 1200 degrees Celsius, preventing CMAS infiltration and maintaining strain tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal barrier coatings are used in high-temperature applications, then thermal protection is provided to the substrate, but the coating becomes susceptible to CMAS infiltration and degradation
Solution Approach 1:
The invention utilizes a porous top coat layer containing voids that are deliberately designed to trap and contain CMAS deposits. The porous structure allows the coating to accommodate CMAS infiltration while preventing it from reaching the bond coat and substrate, thus maintaining coating reliability in high-temperature applications.
Solution Approach 2:
The top coat layer acts as an intermediary barrier between the substrate and CMAS deposits. It provides a sacrificial porous layer that intercepts and contains the harmful CMAS material, protecting the underlying bond coat and substrate from direct exposure and degradation.
2Reliability
If the coating structure includes voids to accommodate CMAS, then CMAS infiltration is prevented, but the coating may lose strain tolerance and undergo delamination
Solution Approach 1:
The coating system employs different layers with distinct properties: the top coat layer is designed with high porosity to locally accommodate CMAS deposits, while the bond coat layer maintains dense structure and strong adhesion to preserve overall coating strength and prevent delamination. This local differentiation of properties allows simultaneous achievement of CMAS resistance and strain tolerance.
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 effectively prevents CMAS infiltration and degradation of thermal barrier coatings, enhancing their durability and reducing the risk of premature failure, thereby extending the lifespan and performance of high-temperature components.
Implementation Method 1
the protective agent comprises a substance capable of chemically reacting with liquid nominal CMAS to form a solid crystalline product
Implementation Method 2
US 2007/ 119713 A1 discloses a method for protecting a thermal barrier coating which comprises voids involving the step of electrophoretically depositing a mitigation coating material such as alumina to fill at least a portion of the voids
Data Source
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AI summary
Articles having coatings that are resistant to high temperature degradation are described, along with methods for making such articles. The article (100) comprises a coating (110) disposed on a substrate (120). The coating (110) comprises a plurality of elongated surface-connected voids (130). The article (100) further includes a protective agent (150) disposed within at least some of the voids (130) of the coating (110); the protective agent (150) comprises a substance capable of chemically reacting with liquid nominal CMAS to form a solid crystalline product outside the crystallization field of said nominal CMAS. This solid crystalline product has a melting temperature greater than about 1200 degrees Celsius. The method generally includes disposing the protective agent (150) noted above within the surface connected voids (130) of the coating (110) at an effective concentration to substantially prevent incursion of CMAS materials into the voids (130) in which the protective agent (150) is disposed.