Tooling Fixture Coatings for Clean CMC Preform Release
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Solution Overview
Problem
Delamination of ceramic matrix composite (CMC) preforms occurs during detooling from tooling fixtures, leading to damage and the need for restarting the process with new preforms.
Innovation Solution
Application of coatings such as ceramic materials, hexagonal boron nitride, turbostratic boron nitride, and graphite on tooling fixture surfaces to facilitate preform release without delamination, while also sealing the fixture to prevent residue contamination during chemical vapor infiltration (CVI) processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If perforated tooling is used to hold preforms during densification, then the preform maintains proper shape and geometry, but delamination occurs during detooling
Solution Approach 1:
A coating layer is applied to the tooling fixture surfaces as an intermediary between the tooling and preform. This coating prevents direct adhesion while maintaining the structural support function of the tooling, thereby preventing delamination during detooling while preserving preform shape and geometry throughout the densification process
2Strength
If tooling fixture is used to maintain preform rigidity, then proper shape is maintained, but preform sticks to tooling causing damage
Solution Approach 1:
The coating serves as a mediator that eliminates harmful adhesion while preserving the beneficial mechanical support. The coating layer is applied to all tooling fixture surfaces including hole surfaces, creating a non-sticking interface that prevents preform damage during removal while maintaining preform rigidity during the densification process
3Ease of manufacture
If tooling fixture surfaces are exposed during CVI process, then manufacturing is simplified, but residue contamination occurs
Solution Approach 1:
The coating acts as a protective intermediary layer on all tooling fixture surfaces including the interior hole surfaces. This coating prevents direct contact between the preform and tooling residue, thereby preventing contamination while maintaining manufacturing simplicity. The coating is applied to all surfaces that would otherwise be exposed to the preform during the CVI process
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
Prevents preform delamination and residue contamination, ensuring successful completion of the CVI process without the need for new preforms.
Implementation Method 1
The coating is disposed on the first surface and surfaces defining the plurality of holes. The coating comprises at least one of a ceramic material, hexagonal boron nitride, turbostratic boron nitride, and graphite.
Implementation Method 2
at least partially densifying the fiber preform with a ceramic matrix through a process of chemical vapor infiltration
Data Source
Figure 1
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AI summary
A tooling fixture (10) is disclosed for densification by chemical vapor infiltration of a fiber preform of a ceramic matrix composite. The tooling fixture (10) includes a body having oppositely disposed first and second surfaces (12, 14) and a plurality of holes (16) extending between the first and second surfaces (12, 14), and a coating (18). The first surface (12) is configured to be disposed adjacent to the fiber preform. The coating (18) is disposed on the first surface (12) and surfaces defining the plurality of holes (16). The coating (18) comprises at least one of a ceramic material, hexagonal boron nitride, turbostratic boron nitride, and graphite.