Multi-layered Aluminium Brazing Sheet for Complex Heat Exchangers
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Solution Overview
Problem
Conventional brazing sheet materials lack sufficient formability to produce complex shapes and do not provide adequate post-braze corrosion resistance, especially in environments with cyclic temperature and pressure variations, such as those encountered in automotive applications.
Innovation Solution
A four-layered brazing sheet material comprising an aluminium core alloy layer, a brazing clad layer, an inter-layer, and a waterside layer, specifically formulated with particular alloy compositions to enhance formability and corrosion resistance, allowing for both vacuum and controlled-atmosphere brazing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional brazing sheet materials are used, then the basic brazing function is achieved, but the formability to produce complex shapes is insufficient
Solution Approach 1:
The brazing sheet is divided into multiple functional layers: a core alloy layer (3xxx-series) providing formability, an inter-layer (1xxx-series aluminium) providing corrosion resistance, and a brazing clad layer (4xxx-series with silicon) providing brazing capability. This segmentation allows each layer to optimize its specific function without compromising the others, enabling complex shape formation while maintaining manufacturing feasibility.
Solution Approach 2:
The invention uses a composite multi-layer structure combining different aluminium alloys with distinct properties. The 3xxx-series core provides ductility for complex shaping, the 1xxx-series inter-layer provides corrosion resistance, and the 4xxx-series clad provides low melting point for brazing. This composite approach resolves the contradiction by integrating multiple material functions into a single manufacturable product.
2Reliability
If conventional brazing sheet materials are used, then the brazing process is completed, but the post-braze corrosion resistance is inadequate
Solution Approach 1:
Different layers are assigned specific quality functions: the inter-layer (1xxx-series aluminium) is positioned at the water-side contact surface to provide corrosion resistance, while the brazing clad layer (4xxx-series) is positioned at the brazing interface to provide low melting point brazing. This local quality assignment ensures each region of the material performs its specific function optimally, achieving high corrosion resistance while managing structural complexity through functional specialization.
3Strength
If the core alloy contains higher copper content to improve strength, then the strength increases, but the formability decreases
Solution Approach 1:
The material is segmented into a core layer optimized for strength (with controlled copper content of 0.6-1.25%) and clad layers that provide formability and brazing properties. The core alloy layer contains 0.6% to 1.25% Cu for strength, while the brazing clad layers contain silicon for low melting point and good formability, resolving the strength-formability contradiction through functional segmentation.
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 multi-layered brazing sheet material achieves high corrosion resistance and thermal stability, enabling extended service life in heat exchanger units and supporting complex substrate production, suitable for various automotive cooling systems.
Implementation Method 1
a brazing filler metal or brazing alloy, or a composition producing a brazing alloy upon heating, is applied to at least one portion of the substrate to be brazed. After the substrate parts are assembled, they are heated until the brazing metal or brazing alloy melts. The melting point of the brazing material is lower than the melting point of the aluminium substrate or aluminium core sheet.
Data Source
AI summary
The invention relates to a multi-layered brazing sheet material consisting of an aluminium core alloy layer provided with a brazing clad layer material on one face of said aluminium core layer and an inter-layer positioned between the aluminium core alloy layer and the brazing clad layer material, and a water-side layer on the other face of the aluminium core layer, wherein the core layer is made from an aluminium alloy having, in wt.%, up to 0.6% Si, up to 0.45% Fe, 0.6% to 1.25% Cu, 0.6% to 1.4% Mn, 0.08% to 0.4% Mg, up to 0.2% Cr, up to 0.25% Zr, up to 0.2% Ti, up to 0.3% Zn, balance aluminium and impurities, wherein the brazing layer is made from an aluminium alloy having 6% to 14% Si and up to 2% Mg, balance aluminium and impurities, and wherein the inter-layer is made from an aluminium alloy of the 1 xxx-series alloys, and wherein the water-side layer is made from a 3xxx-series aluminium alloy having 0.5% to 1.8% Mn and 1 % to 3.5% Zn.