Metal Repair Preform for Brittle CMC Defect Replacement
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Solution Overview
Problem
Conventional techniques for repairing damaged ceramic matrix composite (CMC) articles in gas turbine engines are expensive and prone to further damage due to the brittleness of CMC materials, as they rely on replacing or re-infiltrating damaged areas with costly CMC materials.
Innovation Solution
Mechanical repair of CMC articles using a metal repair preform, specifically a non-reactive nickel alloy or stainless steel, which is attached to the CMC article to complement and replace the damaged portion, reducing costs and susceptibility to further damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMC repair techniques are used (replacing damaged portions with additional fiber or matrix), then the repair maintains material compatibility, but the repair cost increases and the repaired article remains susceptible to further damage due to brittleness
Solution Approach 1:
The invention changes the material parameter of the repair portion from CMC to metal, fundamentally altering the mechanical properties. The metal repair preform provides ductility and toughness that contrasts with the brittle CMC material, thereby reducing susceptibility to further damage while lowering repair costs.
Solution Approach 2:
The invention creates a hybrid composite structure combining metal repair portions with CMC base material. This composite approach leverages the advantages of both materials: the metal provides damage resistance and the CMC maintains thermal resistance, achieving both reliability improvement and cost reduction.
2Temperature
If CMC materials are used for turbine engine components, then thermal resistance and high temperature strength are improved, but brittleness increases leading to damage from overstressing and impact
Solution Approach 1:
The invention applies different material qualities to different regions of the component. The CMC material maintains thermal resistance in areas requiring heat protection, while metal repair portions are strategically placed in areas susceptible to overstressing and impact, creating local optimization of mechanical properties without compromising thermal performance.
Solution Approach 2:
The invention creates a composite structure combining CMC and metal materials, where each material contributes its superior properties. The CMC provides thermal resistance and the metal provides resistance to overstressing and impact, achieving a synergistic effect that overcomes the limitations of using either material alone.
3Ease of manufacture
If metal repair preform is used to replace damaged CMC portions, then repair cost decreases and damage resistance improves, but compatibility with CMC material must be ensured
Solution Approach 1:
The invention changes the material composition parameter by introducing metal as a repair material, which enables cost reduction and improved damage resistance. The selection of specific metal types (such as nickel-based superalloys) ensures compatibility with CMC materials through controlled thermal expansion coefficients and chemical stability at operating temperatures.
Data Source
AI summary
Various embodiments include a metal-repaired ceramic matrix composite (CMC) article, and a method of repairing a CMC article having a defect. Particular embodiments include a method including: removing a defect-containing portion of the CMC article; forming at least one opening in a remaining portion of the CMC article; preparing a metal repair preform for replacing at least the removed portion of the CMC article, wherein a portion of the metal repair preform complements the at least one opening; and attaching the metal repair preform to the remaining portion of the CMC article.