CMAS-Resistant Barrier Coatings With Graded REO Phases
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Solution Overview
Problem
High temperature components face issues with CMAS formation and infiltration due to exposure to siliceous materials, leading to thermal flux, erosion, and environmental contamination, which existing coatings are ineffective in addressing.
Innovation Solution
A barrier coating with a rare-earth disilicate matrix and graded distribution of REO-rich phase regions, which reacts with CMAS to form stable products, reducing infiltration and providing improved thermal and environmental protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing barrier coatings are used to protect high temperature components, then thermal flux and erosion protection are provided, but CMAS infiltration resistance is insufficient
Solution Approach 1:
The coating employs a graded composition where the volume fraction of rare-earth oxide (REO) evolves continuously from the inner interface to the outer surface. The inner region contains lower REO volume fraction while the outer region contains higher REO volume fraction, creating locally optimized properties: the inner region maintains CTE compatibility with the substrate, while the outer region provides enhanced CMAS resistance through REO-rich phase formation.
Solution Approach 2:
The barrier coating is formulated as a composite system containing multiple phases: rare-earth disilicate (RESi2O7), rare-earth monosilicate (RESiO3), and REO-rich phases. This multi-phase composite structure enables simultaneous achievement of thermal stability, mechanical integrity, and chemical resistance to CMAS infiltration through the synergistic interaction of different phases.
2Object-affected harmful factors
If a uniform REO distribution is used in the barrier coating, then manufacturing simplicity is maintained, but CMAS resistance and crack healing are reduced
Solution Approach 1:
The coating employs a graded composition where the volume fraction of rare-earth oxide (REO) evolves continuously from the inner interface to the outer surface. The inner region contains lower REO volume fraction while the outer region contains higher REO volume fraction, creating locally optimized properties: the inner region maintains CTE compatibility with the substrate, while the outer region provides enhanced CMAS resistance through REO-rich phase formation.
Solution Approach 2:
The invention transitions from a uniform, one-dimensional coating structure to a three-dimensional graded structure where REO volume fraction varies through the coating thickness. This dimensional variation enables simultaneous optimization of multiple functions: the inner low-REO region provides CTE matching, while the outer high-REO region provides CMAS resistance and crack healing capability.
3Object-affected harmful factors
If the barrier coating has high REO content throughout, then CMAS resistance is improved, but CTE mismatch with substrate increases
Solution Approach 1:
The coating employs a graded composition where the volume fraction of rare-earth oxide (REO) evolves continuously from the inner interface to the outer surface. The inner region contains lower REO volume fraction while the outer region contains higher REO volume fraction, creating locally optimized properties: the inner region maintains CTE compatibility with the substrate, while the outer region provides enhanced CMAS resistance through REO-rich phase formation.
Solution Approach 2:
The barrier coating is divided into distinct compositional regions: an inner region with lower REO volume fraction for CTE matching, and an outer region with higher REO volume fraction for CMAS resistance. This segmentation allows each region to independently optimize its function without compromising the other.
4Adaptability or versatility
If existing single-phase coatings are used, then manufacturing process is simple, but multi-functionality (thermal barrier, erosion resistance, CMAS resistance) cannot be achieved
Solution Approach 1:
The barrier coating is formulated as a composite system containing multiple phases: rare-earth disilicate (RESi2O7), rare-earth monosilicate (RESiO3), and REO-rich phases. This multi-phase composite structure enables simultaneous achievement of thermal stability, mechanical integrity, and chemical resistance to CMAS infiltration through the synergistic interaction of different phases.
Solution Approach 2:
The graded barrier coating with REO-rich phases provides multiple functions within a single coating system: thermal barrier protection through low thermal conductivity of rare-earth silicates, erosion resistance through mechanical strength, and CMAS infiltration resistance through REO-rich phase formation at the outer surface. This multi-functional design eliminates the need for separate coatings for each protection mechanism.
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 enhances the operational safety and durability of high-temperature components by resisting CMAS infiltration, improving water vapor resistance, and maintaining structural integrity under harsh conditions.
Implementation Method 1
The barrier coating includes a matrix including a rare-earth disilicate extending from an inner interface facing the substrate to an outer surface opposite the inner interface. The barrier coating includes a graded volumetric distribution of rare-earth oxide rich (REO-rich) phase regions in the matrix along a direction from the inner interface to the outer surface.
Data Source
AI summary
An example article includes a substrate and a barrier coating on the substrate. The barrier coating includes a matrix including a rare-earth disilicate extending from an inner interface facing the substrate to an outer surface opposite the inner interface. The barrier coating includes a graded volumetric distribution of rare-earth oxide rich (REO-rich) phase regions in the matrix along a direction from the inner interface to the outer surface. The graded volumetric distribution defines a first volumetric density of the REO-rich phase regions at a first region of the matrix adjacent the outer surface. The graded volumetric distribution defines a second volumetric density of the REO-rich phase regions at a second region of the matrix adjacent the inner surface. The second volumetric density is different from the first volumetric density. An example technique includes forming the barrier coating on the substrate of a component.