Thermal Barrier Coating CMAS Inhibition via Reactive Agent
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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, leading to premature failure and increased maintenance and operating costs due to infiltration and solidification of molten CMAS, which reduces strain tolerance and causes delamination and spalling.
Innovation Solution
A coating system comprising a bond coating, a protective ceramic thermal barrier coating with elongated surface-connected voids, and a reactive protective agent disposed within these voids to rapidly react with and form a solid barrier against CMAS infiltration, minimizing damage and maintaining strain tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermal barrier coating is used to protect turbine components, then thermal protection is provided, but the coating becomes susceptible to CMAS infiltration and degradation at high temperatures
Solution Approach 1:
A reactive protective agent is introduced as an intermediary substance within the thermal barrier coating voids. This agent reacts with CMAS to form a solid barrier layer, preventing direct contact between the molten contaminant and the thermal barrier coating structure, thus protecting the coating while maintaining thermal insulation properties
Solution Approach 2:
The thermal barrier coating utilizes a porous structure with controlled voids that are strategically filled with reactive protective agents. The porosity allows for strain tolerance and thermal shock resistance while the filled voids provide chemical protection against CMAS infiltration through reactive barrier formation
2Strength
If the thermal barrier coating has a porous structure for strain tolerance, then thermal shock resistance is improved, but CMAS can infiltrate through pores and cracks causing delamination
Solution Approach 1:
The reactive protective agent converts the harmful CMAS infiltration process into a beneficial protective mechanism. When CMAS attempts to infiltrate through the porous structure, it reacts with the protective agent to form a solid barrier, transforming the potential damage pathway into a protective barrier formation process
Solution Approach 2:
The reactive protective agent is pre-positioned within the voids and pores of the thermal barrier coating before exposure to CMAS. This preliminary placement ensures immediate reaction and barrier formation upon CMAS contact, preventing deep infiltration and structural damage
3Reliability
If molten CMAS infiltrates the thermal barrier coating pores, then the coating structure is compromised, but infiltration can be prevented by adding protective agents
Solution Approach 1:
The reactive protective agent is nested within the voids and pores of the thermal barrier coating structure. This nested configuration allows the protective agent to be integrated into the existing coating architecture without requiring a separate external protection system, maintaining relatively simple overall structure while providing enhanced functionality
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 coating system effectively prevents CMAS infiltration and solidification, maintaining the thermal protection of the underlying substrate and reducing the risk of premature component failure, thereby extending the lifespan and performance of high-temperature components.
Implementation Method 1
a reactive protective agent disposed within these voids to rapidly react with and form a solid barrier against CMAS infiltration
Implementation Method 2
Thermal barrier coatings are typically used in articles that operate at or are exposed to high temperatures
Data Source
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AI summary
A coating system disposed on a surface of a substrate is provided. The coating system includes a bond coating on the surface of the substrate, a protective coating on the bond coating, a thermal barrier coating on the protective coating, and a protective agent disposed within at least some of the voids of the thermal barrier coating. The protective coating is constructed from a ceramic material, and the thermal barrier coating defines a plurality of elongated surface-connected voids. Methods are also generally provided for forming such a coating system.