Brazing Ceramic Matrix Composite Joints with Anchored Cavities
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Solution Overview
Problem
Brazing of ceramic matrix composite materials is technically challenging due to insufficient breaking stress of brazing joints, high surface roughness, and gas species trapped in the solder joint, leading to weak connections and defects.
Innovation Solution
Creating cavities and grooves on the assembly faces with capillary elements to anchor and distribute the solder, allowing for degassing and ensuring uniform solder presence, thereby enhancing the strength and quality of the brazing connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional brazing is used on CMC parts, then the assembly can be produced, but the breaking stress of the brazing joint is insufficient and the connection is weak
Solution Approach 1:
The invention utilizes the porous structure of CMC materials by creating cavities within the material that can be filled with solder, transforming the porous nature from a potential weakness into a mechanism for enhanced mechanical interlocking and bonding strength
Solution Approach 2:
Cavities are pre-formed in the CMC parts before brazing to prepare anchoring zones for the solder, allowing the solder to mechanically interlock with the part structure and significantly improve joint strength
2Manufacturing precision
If brazing is performed on CMC parts with high surface roughness, then the assembly can be produced, but the solder distribution is poor and weak zones are created
Solution Approach 1:
The invention creates localized cavities with specific geometries and distributions tailored to achieve uniform solder flow and distribution across the bonding surface, compensating for the overall high surface roughness of CMC materials
3Reliability
If conventional brazing heat treatment is applied, then the solder diffuses between parts, but gaseous species are trapped in the solder joint creating porous defects
Solution Approach 1:
The invention extracts or removes gaseous species from the brazing zone by designing cavities that open to the exterior surface, allowing gases to escape during the brazing process rather than becoming trapped in the joint
Solution Approach 2:
The invention introduces a third dimension by creating through-cavities that provide escape pathways for gases, transforming the two-dimensional soldering surface into a three-dimensional structure with internal degassing channels
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 method provides a robust and uniform solder joint with improved anchoring and degassing, reducing the likelihood of weak zones and enhancing the mechanical properties of the composite material connections.
Implementation Method 1
a molten solder being transported by capillarity over the entire brazing zone by means of capillary elements arranged between the assembly faces of the parts made of composite material
Implementation Method 2
thanks to the presence of cavities on at least one of the assembly faces of the parts made of composite material, it is possible to firmly anchor the solder joint in the material of the part
Implementation Method 3
allowing degassing during the soldering cycle, the gaseous species being evacuated by the ends of the cavities opening outside the assembly faces
Data Source
Figure 1A~1B
Figure 1C~1E
Figure 2~5
AI summary
A method of assembling together by brazing two parts made of composite material, each part having an assembly face for brazing with the assembly face of the other part, the method including: making a plurality of cavities in the assembly face of at least one of the two composite material parts, at least some of the cavities opening out into one or more portions of the part that are situated outside the assembly face; interposing capillary elements between the assembly faces of the composite material parts; placing a brazing composition in contact with a portion of the capillary elements; and applying heat treatment to liquefy the brazing composition so as to cause the molten brazing composition to spread by capillarity between the assembly faces of the composite material parts.