CVI Seal Plate Channel Layout for Uniform Preform Densification
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Solution Overview
Problem
Conventional chemical vapor infiltration and deposition (CVI/CVD) systems face challenges in achieving uniform densification and microstructure formation across the thickness of porous structures, often resulting in long processing times.
Innovation Solution
A seal plate design for CVI/CVD chambers featuring a plurality of channels that extend completely through the seal plate, with specific channel configurations and orientations to enhance gas flow and uniform densification, including first and second channels with progressively increasing widths and strategically positioned to facilitate gas entry and exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional seal plates are used in CVI/CVD chambers, then the structure is simple and easy to manufacture, but the densification uniformity across the thickness of porous structures is poor and processing time is long
Solution Approach 1:
The seal plate is segmented into multiple functional regions with different channel configurations. First channels extend completely through the seal plate thickness to provide primary gas flow paths, while second channels extend only partially to provide secondary flow paths. This segmentation allows different regions of the porous structure to receive optimized gas flow, improving densification uniformity across the thickness.
Solution Approach 2:
Different regions of the seal plate are designed with locally optimized channel characteristics. The first channels have progressively increasing widths to match the pressure gradient, while second channels have uniform widths for specific flow distribution needs. This local quality optimization ensures appropriate gas flow rates at different locations, achieving uniform densification.
2Productivity
If conventional seal plates are used in CVI/CVD chambers, then the device is simple, but the processing time is long
Solution Approach 1:
The segmented channel system divides the gas flow into multiple parallel paths (first channels and second channels), increasing the total effective flow area. This reduces flow resistance and allows faster gas penetration through the porous structure, thereby reducing processing time while maintaining uniform densification.
Solution Approach 2:
The channel design transitions from two-dimensional surface features to three-dimensional volumetric flow paths that extend through the seal plate thickness. First channels penetrate completely through the seal plate, creating direct gas flow paths that reduce the diffusion distance and accelerate the densification process.
3Manufacturing precision
If channels with progressively increasing widths are used, then gas flow distribution is optimized for uniform densification, but the manufacturing complexity increases
Solution Approach 1:
The complex progressively increasing width channels are segmented into discrete sections (first channels and second channels) with different geometric characteristics. This segmentation allows each section to be manufactured using simpler techniques while collectively achieving the desired progressive width profile for optimized gas flow distribution.
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 seal plate design improves the uniformity of densification and reduces processing time by optimizing gas flow and distribution within the CVI/CVD chamber, thereby enhancing the quality of composite structures like carbon/carbon brake disks.
Implementation Method 1
a pressure differential driving the gas mixture into the porous structures. The gas enters into the porous structures, driven by pressure gradients
Implementation Method 2
The gas enters into the porous structures, driven by pressure gradients, and undergoes a reaction such as thermal decomposition, hydrogen reduction, co-reduction, oxidation, carbonization, or nitridation to deposit a binding matrix
Implementation Method 3
Chemical vapor infiltration and deposition (CVI/CVD) is a known process for making composite structures
Data Source
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AI summary
A seal plate disposable between a pair of preforms for chemical vapor infiltration is disclosed. The seal plate may include a plurality of first channels (240) that extend completely through the seal plate and that are located between an inner annulus (270) and outer annulus (280) of the seal plate. The seal plate may further include a plurality of second channels that also extend completely through the seal plate and that are located also between an inner annulus and outer annulus. The first channels may differ from the second channels in at least one respect (e.g., the first channels may be of a different width than the second channels). The first (240) may provide an inlet for the chemical vapor infiltration of the preform, while the second channels may provide an outlet for the chemical vapor infiltration of the preform.