Thermal Barrier Coating Restoration Against CMAS Spalling
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Solution Overview
Problem
Thermal barrier coatings in gas turbine engines are prone to damage from environmental contaminants like CMAS, leading to spalling and reduced performance, which requires frequent maintenance and results in downtime and increased costs.
Innovation Solution
A method involving a thermal barrier coating restoration coating that chemically reacts with CMAS contaminants, forming a protective layer without the need for disassembly or pre-treatment, using a reactive phase spray coating to extend the coating's life and prevent further damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If routine maintenance includes washing and reapplying thermal barrier coating, then coating protection is improved, but engine downtime and service loss increase
Solution Approach 1:
The restoration coating is applied in advance to react with CMAS contaminants before they cause severe damage, forming a protective barrier layer that prevents further degradation. This preliminary protective action eliminates the need for frequent maintenance shutdowns, thereby reducing engine downtime while maintaining coating integrity
Solution Approach 2:
The restoration coating chemically reacts with harmful CMAS contaminants to form a beneficial protective barrier layer. Instead of simply preventing contaminant contact, the coating utilizes the contaminants themselves to create a protective interface, converting the harmful chemical interaction into a beneficial protective mechanism that extends coating life without requiring engine disassembly
2Temperature
If thermal barrier coating is exposed to high operating temperatures, then thermal protection function is improved, but CMAS infiltration and spalling increase
Solution Approach 1:
The restoration coating creates a composite structure consisting of the original thermal barrier coating, the CMAS contaminant layer, and the newly applied restoration coating. This multi-layer composite system allows the outer restoration layer to chemically interact with CMAS and form a protective barrier, while the underlying thermal barrier coating maintains its thermal insulation function. The composite structure prevents CMAS infiltration into the original coating while preserving high-temperature thermal protection
Solution Approach 2:
The restoration coating acts as an intermediary layer between the thermal barrier coating and the CMAS contaminants. It chemically reacts with the contaminants to form a protective barrier, preventing direct contact between the harmful CMAS and the original thermal barrier coating. This intermediary layer maintains thermal protection while blocking harmful chemical interactions
3Ease of repair
If engine disassembly is performed for coating reapplication, then coating renewal is improved, but maintenance complexity and cost increase
Solution Approach 1:
The harmful CMAS contaminants are selectively removed or chemically transformed at the coating surface through the restoration coating application, without requiring complete disassembly of the engine. The restoration coating is applied directly to the in-situ thermal barrier coating, extracting only the necessary surface treatment while leaving the engine assembly intact, thereby simplifying the maintenance process
Solution Approach 2:
The restoration coating system enables self-service maintenance by allowing direct application to the thermal barrier coating without requiring engine disassembly or complex preparation procedures. The coating can be applied in-situ and will autonomously react with CMAS contaminants to form the protective barrier, eliminating the need for complex maintenance operations and reducing dependency on extensive engine access
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 protects the thermal barrier coating from CMAS attack, extending its lifespan and reducing maintenance needs by forming a stable protective layer that maintains thermal resistance and prevents spalling, thus minimizing downtime and operational costs.
Implementation Method 1
the TBC restoration coating is configured to chemically react with the layer of environmental contaminant compositions in response to a secondary exposure of the coated component to high operating temperatures of the gas turbine engine to form a protective layer
Implementation Method 2
A reactive phase spray coating is applied at least on the TBC restoration coating. The environmental contaminant compositions comprises CMAS. The reactive phase spray coating provides protection to the TBC restoration coating against the environmental contaminant compositions.
Data Source
Figure 1~2
Figure 3~4
AI summary
A coated component of a gas turbine engine includes a substrate defining a surface, a thermal barrier coating deposited on the surface of the substrate, a region of the component where the thermal barrier coating has spalled from the substrate, a layer of environmental contaminant compositions formed on one or more of the thermal barrier coating or the region of the component where the thermal barrier coating has spalled from the substrate in response to an initial exposure of the component to high operating temperatures of the gas turbine engine, and a thermal barrier coating (TBC) restoration coating deposited at least on the region of the component where there thermal barrier coating has spalled from the substrate.