High-Low Melt Braze Cladding for Low-Stress Component Repair
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Solution Overview
Problem
Existing methods for repairing components using braze filler materials face limitations in achieving effective diffusion bonding and cladding, particularly in maintaining structural integrity and reducing thermal stresses in high-temperature applications like gas turbine engines.
Innovation Solution
A method involving the sequential deposition and sintering of high melt and low melt braze materials on a substrate, where the high melt braze material acts as a buffer to facilitate diffusion bonding and prevent floating, while the low melt braze material enhances bonding and reduces thermal stresses by diffusing into the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single braze material is used for repair, then the process is simple, but diffusion bonding effectiveness and thermal stress reduction are insufficient
Solution Approach 1:
The braze material is segmented into two distinct layers: a high melt braze material layer (first braze material) and a low melt braze material layer (second braze material). This segmentation allows each layer to perform specific functions - the high melt layer provides structural integrity and prevents floating, while the low melt layer enhances diffusion bonding and reduces thermal stresses, thereby resolving the contradiction between bonding effectiveness and process simplicity.
Solution Approach 2:
The invention uses a composite braze material structure consisting of two different braze materials with distinct melting points and compositions. The high melt braze material (e.g., nickel-based superalloy) and low melt braze material (e.g., nickel-phosphorus-boron alloy) work synergistically to achieve both strong diffusion bonding and thermal stress reduction, overcoming the limitations of single-material approaches.
2Reliability
If high melt braze material is used alone, then structural integrity is maintained, but thermal stress reduction is insufficient
Solution Approach 1:
Different regions of the braze material are assigned different properties: the high melt braze material layer provides high strength and structural integrity where needed, while the low melt braze material layer provides thermal stress reduction capabilities at the interface with the substrate. This local differentiation of material properties resolves the contradiction between strength and thermal stress reduction.
Solution Approach 2:
The invention changes the melting point parameter and composition ratio between the two braze material layers. The high melt layer maintains structural strength, while the low melt layer (with lower melting point and specific composition ratios of metal alloy component to braze component) facilitates thermal stress reduction through controlled diffusion and phase transformation, thereby resolving the strength-thermal stress contradiction.
3Manufacturing precision
If braze material is applied without sequential layering, then the process is simpler, but diffusion bonding and cladding quality deteriorate
Solution Approach 1:
The high melt braze material layer is deposited and sintered first to establish a stable foundation and prevent floating during subsequent processing. Then the low melt braze material layer is deposited on top. This preliminary action of creating the high melt layer first ensures that the final cladding achieves high-quality diffusion bonding and proper metallurgical structure, justifying the increased manufacturing complexity.
Solution Approach 2:
The high melt braze material layer acts as an intermediary between the substrate and the low melt braze material layer. It provides a stable base that prevents floating and facilitates controlled diffusion, while allowing the low melt layer to perform its bonding and stress-reduction functions, thereby achieving high cladding quality despite the multi-step deposition 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 approach results in a robust cladding that effectively repairs defects, reduces thermal stresses, and minimizes material distortion, improving the structural integrity and durability of components in high-temperature environments.
Implementation Method 1
The first braze material and the second braze material are heated to melt the first braze material and the second braze material and diffusion bond the first braze material and the second braze material to the substrate
Implementation Method 2
At least some of the low melt braze material diffuses across the high melt braze material into the substrate during the diffusion bonding
Implementation Method 3
The first braze material and the second braze material are heated to melt the first braze material and the second braze material
Data Source
AI summary
A method is provided during which a first braze material is disposed on a substrate. The first braze material has a first melting point. A second braze material is disposed on the first braze material. The second braze material has a second melting point that is less than the first melting point. The first braze material and the second braze material are heated to melt the first braze material and the second braze material and diffusion bond the first braze material and the second braze material to the substrate to provide a cladding on the substrate.