Self-Reinforced EBC Composition for Micro-Crack Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing environmental barrier coatings (EBCs) made from rare earth silicates applied by air plasma spray (APS) are prone to micro-crack formation, which accelerates oxidation of the bond coat and reduces durability due to fast diffusion paths for oxidants.
Innovation Solution
A composition comprising rare earth silicate and aluminum silicate, formulated at or near the eutectic point, forms self-reinforcing fibrous phases during application, reducing micro-crack formation and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth silicate EBC is applied by air plasma spray, then environmental barrier protection is achieved, but micro-cracks form in the coating
Solution Approach 1:
The patent applies a composite material system consisting of rare earth silicate (e.g., Yb2Si2O7) combined with aluminum silicate (Al6Si2O13) in specific proportions. This composite formulation creates a synergistic effect where the aluminum silicate component modifies the microstructure of the rare earth silicate coating, promoting formation of a denser, more crack-resistant microstructure while maintaining the environmental barrier protection properties.
Solution Approach 2:
The patent utilizes eutectic point composition ratios (within 20 mol% or 15 mol% of the eutectic point) to control the microstructure formation during coating application. By precisely controlling the compositional parameters at or near the eutectic point, the coating forms a self-reinforcing microstructure with reduced micro-cracking while maintaining protective functionality.
2Ease of manufacture
If micro-cracks form in EBC, then coating application is simplified, but oxidation of bond coat accelerates
Solution Approach 1:
The composite rare earth silicate-aluminum silicate system inherently forms a more durable microstructure that resists crack formation. The aluminum silicate component contributes to a denser, more cohesive microstructure that prevents the development of micro-cracks during application and service, thereby eliminating the harmful effect of accelerated oxidation while maintaining ease of application.
Solution Approach 2:
The patent eliminates the need for post-application crack repair or complex multi-layer designs by using a fundamentally crack-resistant composite material formulation. The eutectic-point composition creates a self-healing or crack-free microstructure that maintains protective integrity throughout the component service life without requiring additional protective measures.
3Strength
If strengthening fillers are added to EBC composition, then crack formation is reduced, but coating complexity increases
Solution Approach 1:
Instead of adding separate strengthening filler particles, the patent achieves crack resistance by changing the fundamental compositional parameters of the coating material itself. By formulating the rare earth silicate-aluminum silicate system at or near the eutectic point, the material self-reinforces through its inherent microstructure formation, eliminating the need for additional strengthening additives and simplifying the overall composition.
Solution Approach 2:
The composite rare earth silicate-aluminum silicate system is self-reinforcing, where the aluminum silicate component automatically contributes to microstructure densification and crack resistance during the normal coating formation process. The system does not require external strengthening agents or complex multi-component formulations, as the eutectic-point composition inherently provides the necessary mechanical strength and crack resistance.
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 self-reinforced EBCs exhibit significantly reduced micro-cracking, leading to increased erosion resistance and slower thermally grown oxide growth, resulting in improved durability and protection against environmental degradation.
Implementation Method 1
A composition is provided comprising a rare earth silicate and aluminum silicate, in a proportion within 20 mol % or 15 mol % of the eutectic point of the composition
Implementation Method 2
Air plasma spray (APS) processes are often used for the EBC deposition
Implementation Method 3
micro-cracks in the as-sprayed APS coatings, which can provide a fast diffusion path for oxidants
Data Source
AI summary
A self-reinforced environmental barrier coating (EBC), methods of manufacturing the EBC, and articles comprising the EBC, are provided. The EBC is prepared from a composition of a rare earth silicate and an aluminum silicate at or near the eutectic point of the combination. The EBC forms a self-reinforcing fibrous phase that reduces or eliminates microcracks.