Carbon-Sink Intermediate Layer for High-Temperature Ceramic Coatings
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Solution Overview
Problem
Current environmental barrier coatings (EBCs) for ceramic components in high-temperature gas turbine engines face limitations due to the presence of a silicon bond coating, which melts at relatively low temperatures, leading to delamination and reduced operational temperature limits.
Innovation Solution
A carbon-sink intermediate layer is introduced between the ceramic substrate and the EBC, inhibiting the accumulation of free carbon and preventing the formation of carbon oxides, thus eliminating the need for a silicon bond coating and allowing for higher operational temperatures by reacting with free carbon to form stable carbides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon bond coating is used to prevent blistering from carbon oxide formation, then blistering is prevented, but the maximum operating temperature is limited to 1414°C due to silicon melting
Solution Approach 1:
The patent removes the silicon bond coating layer from the coating structure. By extracting this layer, the melting point limitation of 1414°C is eliminated, allowing the EBC to operate at higher temperatures while alternative methods (such as using an oxidation-resistant intermediate layer or modifying the EBC composition) prevent blistering through other mechanisms.
Solution Approach 2:
The patent changes the chemical composition parameters of the intermediate layer or EBC to create a carbon sink that reacts with free carbon to form stable carbides. This parameter change in composition allows the system to prevent carbon oxide blistering without relying on silicon, thereby removing the temperature limitation.
2Reliability
If rare earth silicate compounds are used as EBC materials to seal out water vapor, then recession is prevented, but oxygen penetration occurs causing substrate oxidation and carbon oxide blistering
Solution Approach 1:
The patent introduces an intermediate layer between the ceramic substrate and the rare earth silicate EBC. This intermediate layer acts as a mediator that provides oxidation protection to the substrate while allowing the EBC to maintain its water vapor sealing function. The intermediate layer composition is designed to react with carbon and prevent carbon oxide formation, eliminating blistering while preserving recession protection.
Solution Approach 2:
The patent creates a composite coating structure combining rare earth silicate compounds with additional materials that provide oxidation resistance and carbon reactivity. This composite approach allows the system to simultaneously achieve water vapor sealing, oxidation protection, and blistering prevention without the limitations of using rare earth silicates alone.
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 solution enables ceramic components to operate at higher temperatures without delamination, extending the maximum operational temperature beyond the melting point of silicon, making them suitable for advanced gas turbine applications.
Implementation Method 1
an intermediate layer on the surface of the ceramic substrate. the intermediate layer may include a carbon-sink material that inhibits accumulation of free carbon from a carbon-containing species within the intermediate layer, the ceramic substrate, or both
Data Source
AI summary
Coated components, along with methods of their formation, are provided. The coated component includes a ceramic substrate having a surface; an intermediate layer on the surface of the ceramic substrate; and an environmental barrier coating on the intermediate layer. The intermediate layer includes a carbon-sink material that inhibits accumulation of free carbon from a carbon-containing species within the intermediate layer, the ceramic substrate, or both.