Pin Array for Ceramic Matrix Composite Preform Compression
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Solution Overview
Problem
The processing of ceramic matrix composites (CMCs) faces challenges with uneven matrix infiltration due to tortuous pore networks and surface deformations caused by z-channel formation, leading to defects in composite properties, particularly in gas turbine engines.
Innovation Solution
A pin array is used to apply a compressive force on the preform surface through infiltration holes in a tooling fixture, minimizing surface deformations and facilitating uniform matrix densification by aligning pins with z-channels to prevent fraying and excess matrix formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If z-channels are formed to create direct pathways for reactant gases, then infiltration efficiency is improved, but surface deformations and defects are created
Solution Approach 1:
The pin array is introduced to apply preliminary compressive force to the preform surface during or after z-channel formation, counteracting the surface deformations and fiber fraying that occur during needle perforation. This preliminary anti-action prevents the formation of defects that would otherwise compromise the preform surface quality.
Solution Approach 2:
The pin array serves as an intermediary element between the z-channel formation process and the final preform surface quality. By inserting pins into the preform during perforation, the pins mediate the mechanical stresses and distribute forces uniformly, preventing direct damage to the fiber structure and reducing surface deformations.
2Manufacturing precision
If compressive force is applied to minimize surface deformations, then manufacturing precision is improved, but additional process complexity is introduced
Solution Approach 1:
The compressive force application is segmented into discrete pin locations corresponding to z-channel positions, rather than applying uniform compression across the entire preform surface. This segmentation allows targeted intervention only where needed, simplifying the overall process while maintaining precision.
Solution Approach 2:
The pin array is designed to be self-aligning with the z-channel locations, where pins automatically position themselves at the correct locations during the perforation process. This self-service mechanism eliminates the need for complex alignment systems or additional positioning steps, reducing process complexity while maintaining manufacturing precision.
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 method ensures more uniform densification of CMCs, reducing thermal and aerodynamic impacts by minimizing surface defects and promoting even matrix infiltration, thereby enhancing the properties of CMCs for aerospace applications.
Implementation Method 1
pushing a pin array against a surface of the preform through infiltration holes in the tooling fixture to apply a compressive force on the preform
Implementation Method 2
The pore network through a woven system is often highly tortuous for infiltrating reactant vapors, which leads to uneven deposition through the thickness of the preform
Data Source
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AI summary
A method of forming a ceramic matrix composite includes arranging a plurality of ceramic fibers into a preform (10), mounting the preform (10) within a tooling fixture (18), perforating the preform (10) to form a plurality of z-channels (16), each of the plurality of z-channels (16) extending completely through a thickness of the preform (10), pushing a pin array (24) against a surface (12) of the preform (10) through infiltration holes (20) in the tooling fixture (18) to apply a compressive force on the preform (10), and subsequently, removing the pin array (24) from the surface (12) of the preform (10). The pin array (24) includes a plurality of pins (26) extending from a backplate (28). Each of the plurality of pins (26) is aligned with a respective infiltration hole (20) of the tooling fixture (18).