Flux-Composite Brazing Sheet for Simpler Aluminum CAB Brazing
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Solution Overview
Problem
Current aluminum alloy brazing sheets require complex and costly flux application processes for vacuum or controlled atmosphere brazing, leading to inefficiencies and challenges in production, including residual flux cleanup and scrap recycling issues.
Innovation Solution
A brazing sheet design featuring a core layer with a flux composite layer positioned between filler alloy layers, where the flux is embedded in an aluminum or aluminum alloy matrix, reducing the need for external flux application and simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flux is incorporated into the filler alloy, then brazing performance is improved, but production complexity and scrap recycling difficulty increase
Solution Approach 1:
The invention divides the cladding structure into distinct layers: a flux-free filler alloy layer and a separate flux composite layer containing flux particles in an aluminum matrix. This segmentation allows the filler alloy to be produced without flux contamination, simplifying production and scrap handling, while still providing flux for effective brazing through the separate layer.
Solution Approach 2:
The flux composite layer acts as an intermediary between the filler alloy and the base metal surfaces. It contains the flux particles needed for oxide removal and effective brazing, while being physically separated from the filler alloy. This intermediary structure enables brazing performance without contaminating the filler alloy production process.
2Reliability
If external flux is applied during CAB brazing, then oxide removal is effective, but process complexity and equipment cleaning requirements increase
Solution Approach 1:
The flux is pre-incorporated into the flux composite layer during brazing sheet manufacturing, before the actual brazing operation. This preliminary incorporation eliminates the need for separate flux application steps during CAB brazing, simplifying the manufacturing process while ensuring flux is available where and when needed for effective oxide removal.
Solution Approach 2:
The brazing sheet structure is designed to be self-sufficient by including the flux composite layer as an integral part of the material. The flux particles in this layer automatically become available during brazing to remove oxides, eliminating the need for external flux application and subsequent cleanup operations.
3Ease of manufacture
If flux content is reduced, then scrap recycling is easier, but brazing performance may deteriorate
Solution Approach 1:
By segmenting the flux into a separate flux composite layer distinct from the filler alloy, the invention enables the filler alloy to be free of flux particles. This allows scrap containing filler alloy to be recycled without flux contamination, while the flux composite layer can be managed separately, maintaining brazing performance without compromising recyclability.
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 design enables effective brazing with a lower flux content, reducing production complexities and flux-related scrap, while maintaining good brazing performance and facilitating easier recycling.
Implementation Method 1
The use of flux requires extensive extra process steps, both for its application and in some cases for removal of residual flux, as well as cleaning of the equipment
Implementation Method 2
The brazing operation is normally done in vacuum or in an inert atmosphere (usually dry nitrogen)... CAB brazing is now the dominating technology in commercial applications
Implementation Method 3
a flux composite layer, which flux composite layer comprises a matrix of aluminium or an aluminium alloy, said matrix containing flux particles
Data Source
AI summary
The invention concerns a brazing sheet comprising a core layer (5) and a braze cladding, said core layer (5) being aluminium or an aluminium alloy, said braze cladding comprising (a) a flux composite layer (2), which flux composite layer comprises a matrix of aluminium or an aluminium alloy, said matrix containing flux particles; (b) at least one filler alloy layer (1) not containing flux particles; and, (c) an aluminium or aluminium alloy layer (3) not containing flux particles, said layer forming the outermost surface of at least one side of the brazing sheet, wherein the flux composite layer (a) is positioned between said filler alloy layer (b) and said aluminium or aluminium alloy layer (c). The invention further concerns a method for its manufacturing, a cladding plate, use of the brazing sheet and a brazed heat exchanger.