Brazing Retention Screen for Turbomachinery Gap Filling
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Solution Overview
Problem
Wide gaps in turbomachinery components, such as turbine casings and blades, pose challenges for traditional brazing and welding techniques due to the difficulty in retaining filler materials within the gap, leading to defects like voids and reduced joint strength.
Innovation Solution
A system comprising a gap filling compound (GFC) with a brazing alloy and a retention screen that allows gas escape while maintaining the GFC within the gap, using a mesh or perforated sheet metal screen to contain the filler material and prevent outgassing during the brazing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional brazing techniques are used on wide gaps, then the components can be joined, but the filler material cannot be retained within the gap leading to defects
Solution Approach 1:
A flux composition is introduced as an intermediary substance between the filler metal and the gap surfaces. This flux creates a viscous matrix that traps and retains filler metal particles within the gap during brazing, preventing filler material loss while enabling successful joint formation in wide gaps
Solution Approach 2:
The viscosity of the flux composition is carefully controlled to change with temperature - remaining viscous enough at brazing temperature to retain filler metal particles, but becoming less viscous during cooling to allow easy removal. This parameter change enables both filler retention during processing and easy cleanup afterward
2Reliability
If the gap is filled with brazing alloy, then the gap can be sealed, but gas trapped inside causes defects during brazing
Solution Approach 1:
The flux composition is designed with porous or foam-like characteristics that allow gas to escape through the filler metal particles and flux matrix during brazing. This porous structure enables the gap to remain sealed while providing gas escape pathways, preventing gas entrapment defects
Solution Approach 2:
The flux composition is formulated to react with and neutralize harmful gases generated during brazing, converting them into beneficial or harmless byproducts. This chemical transformation eliminates the harmful effect of gas entrapment while maintaining gap sealing
3Loss of energy
If the component is repaired in place, then transportation costs are reduced, but the repair process becomes more complex
Solution Approach 1:
The flux composition is designed to self-level and self-distribute within the gap during brazing, eliminating the need for complex positioning fixtures or precise application techniques. This self-service characteristic simplifies field repair operations while enabling in-place repair
Solution Approach 2:
The flux composition performs multiple functions simultaneously: it acts as a filler retention medium, a gas escape pathway, a protective atmosphere, and a bonding agent. This multi-functionality consolidates what would otherwise require multiple separate processes into a single integrated repair operation
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 ensures a stronger, more durable repair by retaining the GFC constituents inside the gap, reducing defects and enhancing the longevity of the brazed area, and allows for field repairs of components that are difficult to disassemble and transport.
Implementation Method 1
a brazing alloy and disposed inside the gap a GFC
Implementation Method 2
applying a heat to melt the filler metal in the gap
Implementation Method 3
a GFC retention screen configured to be disposed over the GFC to retain the GFC within the gap during brazing
Data Source
AI summary
Systems and methods are provided for improved brazing. A system includes a gap filling compound (GFC). The GFC includes a brazing alloy. The system also includes a GFC retention screen. The GFC retention screen configured to be disposed over the GFC to retain the GFC within the gap during brazing. The GFC retention screen is also configured to enable gas to escape from the GFC during brazing.