Machinable Ceramic Insert for CMC Fiber Protection
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Solution Overview
Problem
Ceramic matrix composite (CMC) components in gas turbine engines face challenges with machining, as it exposes fibers, leading to potential cracks and reduced tolerance, necessitating a solution to protect the fibers during machining while maintaining high-temperature performance.
Innovation Solution
A ceramic insert is sandwiched between a ceramic matrix composite component and a ply, with the ply extending beyond the insert to join them, and both are co-infiltrated with silicon metal or alloy to form a silicon carbide matrix, allowing for machining without exposing the fibers and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CMC components are machined directly, then machining can be performed, but fibers are exposed leading to cracks and reduced tolerance
Solution Approach 1:
A sacrificial insert made of machinable ceramic material is introduced as an intermediary between the machining tool and the CMC component. This insert provides a protective interface that can be machined without exposing the underlying CMC fibers, thereby maintaining manufacturing precision while enabling ease of manufacture.
Solution Approach 2:
The component is divided into two functional parts: a sacrificial insert that serves as the machining interface and the permanent CMC component that provides structural integrity. The insert can be separately manufactured and attached, allowing independent optimization of machining properties without compromising the CMC component's fiber structure.
2Reliability
If a sacrificial insert is used to protect fibers during machining, then fiber exposure is prevented, but the device complexity increases
Solution Approach 1:
The sacrificial insert is made from the same ceramic matrix composite material as the permanent component, ensuring homogeneous material properties and compatible processing. This eliminates the need for different material systems and simplifies the overall device structure while maintaining fiber protection.
Solution Approach 2:
The sacrificial insert is designed to be temporarily attached during machining operations and then removed or discarded after serving its protective function. This approach provides fiber protection during the critical machining phase without permanently increasing device complexity, as the insert is not part of the final assembled structure.
3Strength
If ply is added to cover the insert and join components, then bonding is enhanced, but manufacturing complexity increases
Solution Approach 1:
The ply that covers the sacrificial insert and joins the CMC component is integrated into the same manufacturing process as the insert attachment. The ply is applied and cured simultaneously with the insert bonding operation, combining multiple functions (protection, joining, and structural reinforcement) into a single manufacturing step, thereby enhancing bonding strength without proportionally increasing manufacturing 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
This method enables machining of CMC components without fiber exposure, reducing the risk of cracks and maintaining high-temperature performance by forming a continuous ceramic matrix that protects the fibers and enhances bonding between components.
Implementation Method 1
co-infiltrating the ceramic preform and the ply with silicon metal or silicon alloy to form a silicon carbide matrix that extends through the ceramic preform and the ply
Data Source
AI summary
An assembly comprising a ceramic matrix composite component, a ceramic insert, and a ply and a method for producing the same. The ceramic matrix composite component may comprise silicon carbide fibers in a silicon carbide matrix. The ceramic inset may be adjacent to the ceramic matrix composite component. The ply may at least partially cover the ceramic insert such that the ceramic insert may be sandwiched between the ply and the ceramic matrix composite component, and the ply may extend beyond the ceramic insert in at least one direction so that the ply is joined to the ceramic matrix composite. The ply may comprise at least one layer of silicon carbide fibers or carbon fibers in a silicon carbide matrix.