Gradient tow ribbonizing for chemical vapor infiltration ceramic matrix composites
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Solution Overview
Problem
Existing methods for preparing ceramic matrix composites struggle to control microstructure distribution within preform structures, particularly in gas turbine engine components, where a uniform microstructure is crucial for achieving optimal mechanical and thermal properties.
Innovation Solution
The method involves transforming ceramic tows from one geometry to another, reducing one dimension and increasing another, to create flattened tows. These transformed tows are then woven or braided to form ceramic fabrics with specific inter-tow pore sizes, which are subsequently separated into plies and arranged to form a preform structure with an inter-tow pore size gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional ceramic tows are used without transformation, then the manufacturing process is simple, but the inter-tow pore size distribution is uniform and cannot be optimized for different regions
Solution Approach 1:
The patent applies local quality by transforming ceramic tows into flattened ribbons with different geometries for different applications. The tow transformation process creates ribbons with controlled thickness and width variations, allowing different regions of the preform to have optimized microstructures tailored to specific performance requirements, thereby resolving the contradiction between manufacturing precision and device complexity.
Solution Approach 2:
The patent segments the ceramic fabric into multiple plies with different inter-tow pore size characteristics. By separating the fabric into individual plies, the invention enables selective arrangement of plies with different ribbon geometries to create gradient microstructures, achieving precise microstructure distribution control while managing the complexity through systematic ply organization.
2Volume of stationary object
If ceramic fabrics with small inter-tow pore sizes are used, then the final density is higher, but the matrix deposition during chemical vapor infiltration is restricted
Solution Approach 1:
The patent changes the geometric parameters of ceramic tows by transforming them into flattened ribbons with controlled thickness and width. This parameter transformation creates an optimized balance where the ribbons are thin enough to allow matrix vapor infiltration while maintaining sufficient structural integrity and achieving high final density, thereby resolving the contradiction between density and manufacturability.
3Manufacturing precision
If ceramic tows are transformed to flattened ribbons, then the inter-tow pore size is reduced and microstructure is controlled, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by transforming ceramic tows into flattened ribbons before weaving them into fabrics. This pre-transformation approach allows precise control of inter-tow pore sizes to be established upfront, simplifying subsequent manufacturing steps while achieving the desired microstructure precision, thereby resolving the contradiction between manufacturing precision and 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
This approach enables the production of ceramic matrix composites with improved interlaminar properties, such as increased interlaminar tensile strength, shear strength, and thermal conductivity, while achieving higher final density and uniform microstructure.
Implementation Method 1
transforming the first ceramic fabric from the first average inter-tow pore size to a third average inter-tow pore size by applying a first pressure to opposite sides of the first ceramic fabric
Data Source
AI summary
A method of preparing a ceramic fabric and ceramic matrix composite components constructed from the ceramic fabric include transforming ceramic tows, or ceramic fabrics, to varying degrees from a first tow geometry to a second tow geometry, thereby reducing a first dimension of the ceramic tows and increasing a second dimension of the ceramic tows orthogonal to the first dimension. Plies constructed with flattened tows, or as-received tows, have various inter-tow pore sizes that are arranged with increasing inter-tow pore size towards exterior surfaces of the preform structure.