Hourglass-Shaped Voids in Ceramic Preforms for Uniform Infiltration
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Solution Overview
Problem
In ceramic matrix composites, large voids between adjacent tows in woven systems lead to uneven matrix infiltration, resulting in porous midplanes and slower densification processes due to tortuous pore networks and surface deposition of reactant vapors.
Innovation Solution
Perforating fibrous ceramic preforms with spiked arrays to create hourglass-shaped voids facilitates even matrix infiltration by aligning reactant vapors with the midplane, ensuring uniform deposition and reducing porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If woven fibrous preforms are used in ceramic matrix composites, then structural integrity is improved, but large voids between adjacent tows create tortuous pore networks that lead to uneven matrix infiltration and porous midplanes
Solution Approach 1:
The preform is segmented into multiple layers with different tow orientations (e.g., 0°, 90°, ±45° layers), and voids are strategically created between specific tow bundles. This segmentation allows reactant vapors to access different regions of the preform more uniformly, preventing the tortuous pore networks that occur in conventional single-layer woven structures.
Solution Approach 2:
Rather than uniformly modifying the entire preform, voids are selectively created only between specific adjacent tow bundles where they are most needed for vapor access. The local quality of the preform structure is enhanced by having controlled void spaces in critical regions while maintaining the integrity of the woven fabric in other areas.
2Quantity of substance
If reactant vapors infiltrate woven preforms through tortuous pore networks, then matrix deposition occurs, but higher concentrations deposit on preform surfaces and edges rather than uniformly throughout
Solution Approach 1:
Voids are pre-formed between adjacent tow bundles before the matrix infiltration process begins. This preliminary action creates predetermined pathways that guide reactant vapors into the interior regions of the preform, ensuring that deposition occurs uniformly throughout the entire preform volume rather than concentrating only on surfaces and edges.
3Ease of manufacture
If conventional woven preforms are used, then fabrication is straightforward, but the infiltration process is slower and less uniform resulting in porous midplanes
Solution Approach 1:
The preform is divided into multiple layers with controlled void spaces between specific tow bundles, creating a segmented structure that facilitates vapor penetration. This segmentation maintains relative ease of fabrication through conventional weaving techniques while dramatically improving infiltration rate and uniformity by providing direct vapor access pathways to the preform interior.
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 achieves uniform matrix distribution within the composite, reducing final porosity to less than 20% and enhancing the mechanical integrity of ceramic matrix composites.
Implementation Method 1
Perforating fibrous ceramic preforms with spiked arrays to create hourglass-shaped voids
Implementation Method 2
ensuring uniform deposition and reducing porosity
Implementation Method 3
reactant vapors aligning with the midplane
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A method of preparing a fibrous preform (10) for use in a ceramic matrix composite comprises arranging the preform (10) from a woven ceramic material, the preform (10) comprising a pair of opposing outer surfaces (12) and a midplane (M) disposed between the pair of opposing outer surfaces (12), and perforating the preform (10) with a spiked array (22) to form a perforated preform (10). The perforated preform (10) comprises a plurality of hourglass-shaped voids extending through a thickness (T) of the preform (10).