3D Woven Ceramic Insert Porosity for Uniform CMC Infiltration
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Solution Overview
Problem
Ceramic matrix composite (CMC) components with variable wall thickness face challenges in achieving high and uniform density during chemical vapor infiltration (CVI) due to the use of space filling inserts that are too small or large for standard woven cloth or individual fiber tows, leading to issues with voids and uneven matrix infiltration.
Innovation Solution
The use of 3D woven ceramic inserts with a gradient porosity, formed from multiple regions with varying fiber volume fractions and porosities, facilitates even matrix infiltration by adjusting the porosity and fiber volume fraction to ensure uniform density in CMC components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If space filling inserts are used to fill voids in CMC components, then voids are prevented and wall thickness is built up, but uniform density and high density through CVI process are difficult to achieve
Solution Approach 1:
The insert is designed with spatially varying porosity, where different regions have different porosity values. The first region has lower porosity while the second region has higher porosity, allowing each region to be optimized for its specific function: the lower porosity region provides structural integrity and resists over-infiltration, while the higher porosity region facilitates precursor penetration and prevents void formation.
Solution Approach 2:
The porosity parameter is varied within the insert structure to optimize CVI performance. By changing the porosity from the first region to the second region, the insert creates a gradient that controls the infiltration process, ensuring uniform density throughout the final CMC component while maintaining effective void filling.
2Ease of manufacture
If standard woven cloth or individual fiber tows are used, then manufacturing is simpler, but they cannot form regions of variable wall thickness effectively
Solution Approach 1:
The insert is divided into multiple regions with distinct porosity characteristics. This segmentation allows the single insert component to perform multiple functions: filling voids, building wall thickness, and controlling density distribution, thereby replacing what would otherwise require multiple different materials or complex manufacturing steps.
Solution Approach 2:
The insert functions as a composite structure with regions of different porosity, effectively combining the properties of both dense and porous materials within a single component. This composite approach enables the insert to simultaneously provide structural support and facilitate uniform matrix infiltration, achieving variable wall thickness with a single manufacturable component.
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 gradient porosity in the 3D woven inserts allows for a more uniform distribution of matrix precursor material, resulting in a uniformly dense CMC component by ensuring sufficient precursor reaches all regions, including those with higher porosity, thus enhancing the CVI process.
Implementation Method 1
The gradient arrangement enables a more even matrix infiltration of the insert and encompassing preform structure
Implementation Method 2
chemical vapor infiltration (CVI) process
Data Source
AI summary
A ceramic fiber preform includes a plurality of ceramic fiber plies arranged to define a wall, a void adjacent the wall, and an insert positioned within the void. The insert includes a first region having a first porosity and a second region in physical contact with the first region and having a second porosity. The first region and second region are formed from a woven ceramic material, the wall has a wall porosity, and the first porosity is less than at least one of the second porosity and the wall porosity.