CMC Pre-Form Cavity Formation via Mandrel Melt-Out
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Solution Overview
Problem
Existing methods for forming ceramic matrix composite (CMC) components with cavities, such as turbine blades and vanes, face challenges including fragility during the burn-out cycle, labor-intensive cap creation, and potential damage during assembly, due to the use of fragile pre-forms and separate forming processes.
Innovation Solution
A method for forming CMC pre-forms with cavities that includes an opening for mandrel melt-out and cleaning, a durable tip cap combination, reduced ply volume for controlled melt-out, and the ability to inspect cavities before lay-up, allowing for better process control and dimensional accuracy through tailored mandrel materials and an integrated lay-up tool process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cap or plug is inserted after the burnout cycle to close the open end area, then the hollow region is closed off for turbine use, but the CMC pre-form is in its most fragile state making the assembly process time-consuming and labor-intensive
Solution Approach 1:
The tip cap is formed and prepared before the burnout cycle. During the burnout cycle, the mandrel is removed and the tip cap is positioned in the open end area of the CMC pre-form while it is still in a relatively stronger state (post-burnout but pre-densification). This preliminary preparation avoids the need for complex assembly operations after the pre-form becomes extremely fragile.
Solution Approach 2:
The tip cap serves as an intermediary component that bridges the gap between the CMC pre-form and the final closed structure. It is formed from a plurality of plies and shaped to fill the open end, providing a durable closure without requiring separate forming, cutting, and layup processes for each component.
2Reliability
If separate forming, cutting and layup processes are used to create a closed structure, then the CMC pre-form can be closed off, but the process becomes time and labor intensive
Solution Approach 1:
The tip cap formation and CMC pre-form creation are merged into a single integrated process. The tip cap is formed from a plurality of plies that are shaped to fill the open end of the CMC pre-form in one operation, eliminating the need for separate forming, cutting, and layup processes that would otherwise be required.
Solution Approach 2:
The tip cap structure serves multiple functions: it closes the open end area, provides structural support, and integrates with the CMC pre-form to create a complete turbine component. This multi-functionality eliminates the need for multiple separate operations and reduces overall manufacturing complexity.
3Reliability
If the CMC laminate and pre-form are assembled when both are fragile prior to densification, then the closed structure can be formed, but the components can be easily damaged during assembly
Solution Approach 1:
The tip cap is formed and positioned before the final densification cycle. By preparing the closure structure in advance while the CMC pre-form is still in a relatively stronger post-burnout state, the assembly can be completed before the components become extremely fragile during subsequent processing steps.
Solution Approach 2:
The tip cap provides a protective closure that shields the internal cavity structure during handling and assembly operations. This beforehand protective measure prevents damage to the fragile CMC components by providing a structural barrier that reduces the risk of damage during the assembly 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
This method results in a more robust and efficiently produced CMC pre-form with cavities, reducing the risk of damage and improving the control over the manufacturing process, leading to higher quality and more reliable CMC components for gas turbines.
Implementation Method 1
the mandrel is removed through a burn-out cycle. In the burn-out cycle, the mandrel forming materials, such as, various polymers, or other meltable materials are melted out.
Implementation Method 2
a process that includes the application of heat at various processing stages
Implementation Method 3
the mandrel is removed through a burn-out cycle. In the burn-out cycle, the mandrel forming materials, such as, various polymers, or other meltable materials are melted out.
Data Source
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AI summary
A pre-form CMC cavity and method of forming pre-form CMC cavity for a ceramic matrix component includes providing a mandrel (110), applying a base ply (112) to the mandrel (110), laying-up at least one CMC ply (114) on the base ply (112), removing the mandrel, (110) and densifying the base ply (112) and the at least one CMC ply (114). The remaining densified base ply (112) and at least one CMC ply (114) form a ceramic matrix component having a desired geometry and a cavity formed therein. Also provided is a method of forming a CMC component.