CMC Barrier Segment for Re-Infiltration Flow Control
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Solution Overview
Problem
During the infiltration process of composite components, free silicon or other constituents from a previously infiltrated CMC component can migrate to green, uninfiltrated material, leading to weakening of the original CMC component and causing voids, cracks, or other undesirable elements.
Innovation Solution
A barrier segment with lower permeability is introduced between the infiltrated and green segments, featuring a different microstructure than both, to slow or prevent the migration of constituents like silicon, ensuring that flow originates from an external source during infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If green, uninfiltrated material is laid up with the original CMC component and subjected to infiltration, then porosity is reduced and the green material is strengthened, but free silicon or other constituents in the original CMC component migrate to the green material, weakening the original CMC component
Solution Approach 1:
The component is divided into three distinct segments: the original infiltrated segment, the green segment, and a barrier segment positioned between them. This segmentation prevents direct contact and material migration between the infiltrated and green segments during the infiltration process, allowing the green segment to be densified without compromising the original component's strength.
Solution Approach 2:
A barrier segment is introduced as an intermediary layer between the infiltrated segment and the green segment. This barrier segment has lower permeability and acts as a mediator that blocks the migration of free silicon and other constituents from the infiltrated segment to the green segment, while still allowing the infiltration process to proceed effectively in the green segment.
2Reliability
If a barrier segment with lower permeability is introduced between infiltrated and green segments, then constituent migration is prevented, but the device complexity increases
Solution Approach 1:
The barrier segment is positioned locally only at the interface between the infiltrated and green segments where material migration is a concern. This localized approach provides the necessary protection against constituent migration only where needed, rather than requiring a complete redesign of the entire component structure, thus minimizing the increase in complexity.
Solution Approach 2:
The barrier segment is formed from composite material with a microstructure specifically designed to have lower permeability than both the infiltrated and green segments. This use of composite materials with tailored properties allows the barrier function to be achieved through material selection rather than complex structural design, reducing overall device 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 barrier segment effectively prevents the redistribution of constituents from the infiltrated segment to the green segment, maintaining the integrity and strength of the original CMC component by controlling fluid velocity and permeability, thus enhancing the modification process without requiring different materials or chemical changes.
Implementation Method 1
the barrier segment has a lower permeability, e.g., through a different microstructure, than one or both of the infiltrated segment and the green segment to slow or prevent migration or redistribution of material from the infiltrated segment to the green segment during infiltration of the assembly
Implementation Method 2
silicon may be added during densification of the newly formed CMC green segment during an infiltration process
Data Source
Figure 1
Figure 2(A)~2(D)
Figure 3
AI summary
A method (400) for modifying a composite component (100) may include positioning (412) a barrier segment (108) between an infiltrated segment (100') of the composite component (100) and a green segment (106) to form an assembly (116) and initiating (414) an infiltration process. The barrier segment (108) may have a barrier segment permeability (Kbarrier) that is lower than a permeability (Kinfiltrated) of the infiltrated segment (100'), a permeability (Kgreen) of the green segment (106), or both. A composite component (100) may include an infiltrated segment (100') infiltrated with a molten material during a prior infiltration process; a green segment (106) that is uninfiltrated; and a barrier segment (108) having a microstructure different from the infiltrated segment (100'), the green segment (106), or both. The microstructure of the barrier segment (108) may be configured to slow a flow of material between the infiltrated segment (100') and the green segment (106) during a subsequent infiltration process.