Ceramic Matrix Composite Secondary Interface Coating Crack Deflection
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Solution Overview
Problem
Gas turbine engine components face challenges due to high temperatures, corrosive, and oxidative conditions, leading to potential cracking and degradation of ceramic matrix composites, which can expose reinforcements to environmental attack and reduce mechanical integrity.
Innovation Solution
A method involving the application of ceramic-based reinforcements with an interface coating, a primary ceramic matrix layer, and a secondary interface coating, where the secondary coating is distinct and separate from the matrix layers, using chemical vapor infiltration (CVI) to achieve specific thicknesses, helps in deflecting cracks and protecting against oxidant ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic matrix composite component is used in high temperature and corrosive conditions, then the component can maintain structural integrity, but cracks may propagate and expose reinforcements to environmental attack
Solution Approach 1:
The coating structure is segmented into multiple distinct layers: a first ceramic-based matrix layer, a secondary interface coating layer, and a second ceramic-based matrix layer. This segmentation creates multiple barriers that can independently deflect or arrest cracks, preventing them from propagating through the entire composite structure and exposing the reinforcement fibers to environmental attack.
Solution Approach 2:
The invention uses a composite coating structure combining different materials: ceramic-based matrix material for thermal and mechanical stability, and a secondary interface coating material that provides crack deflection capability. This multi-material composite approach leverages the complementary properties of each material to achieve both high-temperature resistance and crack propagation resistance.
2Object-affected harmful factors
If a thick ceramic matrix layer is applied to protect against environmental attack, then protection is improved, but the coating may become more prone to cracking
Solution Approach 1:
Instead of applying a single thick matrix layer, the invention segments the protective coating into multiple thinner matrix layers separated by a secondary interface coating layer. This segmentation reduces the stress concentration in each individual matrix layer, making them less prone to cracking while collectively providing thick protective coverage against environmental attack.
Solution Approach 2:
The secondary interface coating layer acts as an intermediary between the two ceramic matrix layers. This intermediate layer has different mechanical properties that allow it to absorb stress and deflect cracks, preventing crack propagation through the matrix layers while maintaining the protective thickness needed for environmental resistance.
3Object-affected harmful factors
If multiple layers of ceramic matrix are applied, then protection against environmental attack is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The coating process uses periodic application and removal cycles in the chemical vapor infiltration (CVI) process. The CVI process is performed, then halted to allow formation of the secondary interface coating layer, then resumed to complete the matrix layer. This periodic action enables precise control over layer formation and thickness while using a single established manufacturing technique.
Solution Approach 2:
The invention controls the deposition parameters of the CVI process to achieve the desired layer structure. By adjusting deposition time, temperature, and precursor flow rates, the process creates distinct layers with controlled thicknesses and properties, enabling complex multi-layer structures through parameter control rather than process complexity.
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 minimizes crack propagation and protects the components from oxidant attack, maintaining mechanical integrity and extending the lifespan of the composite materials by creating a protective barrier that discourages crack growth and environmental degradation.
Implementation Method 1
The coating layers are applied using chemical vapor infiltration (CVI)
Data Source
AI summary
A method of making a ceramic matrix composite component includes arranging a plurality of ceramic-based reinforcements in an array, applying an interface coating to the ceramic-based reinforcements, applying a layer of ceramic-based matrix over the interface coating, and applying a secondary interface coating such that the secondary interface coating is separate and distinct from the layer of ceramic-based matrix. A ceramic matrix composite component is also disclosed.