Multilayer Brazing Sheet for Vacuum Applications
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Solution Overview
Problem
Multi-layer brazing sheets made from aluminum alloys face limitations in vacuum brazing due to zinc contamination, which affects the vacuum brazing process and requires alternative compositions and structures that provide corrosion protection without zinc.
Innovation Solution
A multi-layer sheet material with a core layer of 3XXX aluminum alloy and interliner and brazing layers of specific aluminum alloy compositions, including magnesium, to enhance corrosion protection and brazeability while avoiding zinc, thereby preventing furnace contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zinc is used as liner or interliner layers for multi-layer brazing sheets to provide corrosion protection, then corrosion protection is improved, but zinc contaminates the vacuum braze furnace and negatively impacts the vacuum brazing process
Solution Approach 1:
The patent removes zinc from the multi-layer brazing sheet composition entirely, extracting the harmful substance while maintaining the protective function through alternative aluminum-based alloying elements such as magnesium and manganese in the interliner layers
Solution Approach 2:
The patent changes the chemical composition parameters of the interliner layers by specifying aluminum alloys with controlled amounts of magnesium (0.1-1.10 wt%), manganese (up to 0.3 wt%), and other elements, replacing zinc-based corrosion protection with aluminum-based alloying
2Adaptability or versatility
If alternative aluminum alloy compositions without zinc are used to prevent furnace contamination, then vacuum brazing process compatibility is improved, but corrosion protection capability may be reduced
Solution Approach 1:
The patent creates a composite multi-layer structure with a core layer (3XXX aluminum alloy), interliner layers (5XXX aluminum alloy with specific composition), and brazing layers (4XXX aluminum alloy), where each layer contributes different properties to achieve both vacuum brazing compatibility and corrosion protection
Solution Approach 2:
The patent applies different alloy compositions to different layers: the interliner layers contain magnesium and manganese for corrosion protection, the core layer has specific silicon and iron content for mechanical properties, and the brazing layers have controlled zinc content for brazing performance, with each layer optimized for its specific function
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 solution provides improved corrosion protection, strength, and brazeability, with higher post-braze tensile strength and reduced erosion, effectively addressing the limitations of existing multi-layer brazing sheets in vacuum brazing applications.
Implementation Method 1
the core layer is treated by a pre-hot rolling thermal treatment
Implementation Method 2
Multi-layer brazing sheets made from aluminum alloys are known for use in controlled atmosphere brazing (CAB)
Data Source
AI summary
A five layer sheet for vacuum brazing has a core layer of 3XXX aluminum alloy and two interliner layers of 5XXX aluminum alloy bonded to the core layer. Two layers of 4XXX aluminum alloy are bonded to the two interliner layers. An elevated quantity of Mg in the interliner layers can provide enhanced strength, facilitate brazing and provide corrosion protection. A low zinc composition for the sheet also facilitates vacuum brazing.