Aluminum Brazing Sheet Structure for Corrosion and Formability
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Solution Overview
Problem
Existing plate-type heat exchangers face challenges in achieving both corrosion resistance and formability due to the formation of brown bands in H-temper core layers, which are resistant to corrosion but have poor formability, while O-temper core layers are more formable but susceptible to corrosion.
Innovation Solution
A brazing sheet comprising a core layer made of a partially recrystallized 3XXX or 6XXX series aluminum alloy, an unrecrystallized interliner layer made of a 3XXX series aluminum alloy with zirconium, and a brazing layer made of a 4XXX series aluminum alloy, designed for controlled atmospheric or vacuum brazing, to enhance corrosion resistance and formability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If H-temper core layer is used, then corrosion resistance is improved, but formability deteriorates
Solution Approach 1:
The patent applies local quality by creating different temper conditions in different layers of the brazing sheet. The core layer is provided with H-temper for corrosion resistance, while the interliner layer is provided with a different temper condition that allows for better formability. This local differentiation of material properties resolves the contradiction between corrosion resistance and formability by assigning each property to the most appropriate layer.
Solution Approach 2:
The patent uses composite materials by combining multiple layers with different temper conditions and compositions. The brazing sheet comprises a core layer with H-temper aluminum alloy and an interliner layer with different temper characteristics. This composite structure allows the overall material to exhibit both high corrosion resistance (from the H-temper core) and good formability (from the interliner layer with appropriate temper).
2Ease of manufacture
If O-temper core layer is used, then formability is improved, but corrosion resistance deteriorates
Solution Approach 1:
The patent resolves this contradiction by assigning different temper conditions to different layers. The core layer maintains H-temper for corrosion resistance, while the interliner layer is specifically treated to provide the necessary formability. This local quality differentiation ensures that each layer performs its primary function without compromising the other.
Solution Approach 2:
The composite structure of the brazing sheet with multiple layers having different temper conditions allows the material as a whole to achieve both good formability and corrosion resistance. The interliner layer with appropriate temper provides formability during manufacturing, while the H-temper core layer ensures corrosion resistance in the final product.
3Reliability
If brazing sheet is designed for corrosion resistance, then liquid film migration is prevented, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the brazing sheet into distinct layers (core layer and interliner layer) with specific functions. The core layer provides corrosion resistance through H-temper treatment, while the interliner layer facilitates manufacturing through appropriate temper conditions. This segmentation allows each layer to be optimized independently, reducing overall manufacturing complexity while maintaining corrosion resistance.
Solution Approach 2:
The composite brazing sheet structure with multiple layers having different temper conditions and compositions enables the material to achieve corrosion resistance without excessive manufacturing complexity. By carefully selecting the temper conditions for each layer, the patent creates a composite material that is both corrosion-resistant and manufacturable using standard industrial processes.
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 brazing sheet provides improved corrosion resistance and formability by inhibiting liquid film migration and brown band formation, ensuring robust performance in heat exchangers like oil coolers and liquid cooled condensers.
Implementation Method 1
The core layer of the brazing sheet is at least partially recrystallized, such that, for example, the core layer comprises a dislocation density no greater than 10,000,000 per cm2
Implementation Method 2
The interliner layer of the brazing sheet is unrecrystallized, such that, for example, the interliner layer does not comprise recrystallized grains that have a dislocation density no greater than 10,000,000 per cm2
Implementation Method 3
The interliner liner of the brazing sheet comprises a second aluminum alloy. In various non-limiting embodiments, the second aluminum alloy comprises, in weight percentage based on the total weight of the second aluminum alloy, at least 0.01 zirconium
Data Source
AI summary
Brazing sheets, articles formed from or including all or a portion of brazing sheets, and methods of forming articles are provided. A brazing sheet comprises a core layer, a brazing layer, and an interliner layer intermediate the core layer and the brazing layer. The core layer comprises a first aluminum alloy and the core layer is at least partially recrystallized. The brazing layer comprises a 4XXX series aluminum alloy. The interliner layer comprises a second aluminum alloy, and the interliner layer is unrecrystallized.