CVI Tooling Fixture Hole Layout for Uniform CMC Gas Infiltration
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Solution Overview
Problem
Existing tooling for chemical vapor infiltration (CVI) of complexly-shaped preforms, such as turbine airfoils, results in differential deposition rates and effective interface coating thickness, leading to variations in mechanical behavior and durability of ceramic matrix composite (CMC) parts due to insufficient infiltration of vaporous precursors.
Innovation Solution
The development of tooling fixtures with angled and widened infiltration holes, featuring corners greater than 90 degrees, to minimize pressure losses and flow vortices, ensuring uniform reactant gas flow and consistent IFC deposition across the preform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform hole dimensions are used in tooling for simple preform shapes, then manufacturing simplicity is maintained, but infiltration sufficiency deteriorates when used with complexly-shaped preforms such as turbine airfoils
Solution Approach 1:
The patent applies local quality by varying the hole dimensions (diameter, length, orientation) in different locations of the tooling fixture according to the specific geometric requirements of complex preform shapes. This ensures that each region of the preform receives adequate reactant gas flow for proper infiltration, while maintaining a systematic approach to manufacturing.
Solution Approach 2:
The patent changes the parameters of the holes (diameter, length, orientation angles) to optimize reactant gas distribution. By adjusting these parameters based on preform geometry, the system achieves both adequate infiltration (improved reliability) and systematic manufacturing (maintained ease of manufacture).
2Device complexity
If conventional tooling is used for complexly-shaped preforms, then device simplicity is maintained, but deposition uniformity deteriorates resulting in differential IFC thickness
Solution Approach 1:
The tooling fixture incorporates locally optimized hole characteristics (varying diameters, lengths, and orientations) to achieve uniform reactant gas distribution across complex preform surfaces. This local customization enables consistent interface coating thickness while maintaining overall tooling functionality.
Solution Approach 2:
The patent introduces additional degrees of freedom in hole orientation and positioning to control gas flow distribution. By utilizing angular orientations and three-dimensional hole arrangements, the system achieves uniform deposition across complex geometries without requiring overly complex tooling structures.
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 improved tooling fixtures ensure uniform infiltration and deposition, enhancing the mechanical consistency and durability of CMC parts by minimizing pressure losses and flow disruptions.
Implementation Method 1
vaporous precursors to infiltrate into the preform for the deposition of a ceramic matrix
Implementation Method 2
deposition of a ceramic matrix
Implementation Method 3
minimize pressure losses and flow vortices
Data Source
AI summary
A tooling fixture suitable for use in infiltrating a fibrous preform with a flow of reactant gas includes at least one wall. The at least one wall includes an outer surface and opposing inner surface defining a thickness therebetween, and a plurality of holes extending through the thickness. Each hole of the plurality of holes includes an inlet at the outer surface, an outlet at the inner surface, a transition point between the inlet and the outlet, and a first corner defined by the outer surface and the inlet. An angle of the first corner is less than 90 degrees, each hole of the plurality of holes has a first diameter at the inlet and a second diameter at the outlet, and the second diameter is less than the first diameter.