Fluxless Brazing Cladding Alloys for Oxide Film Removal
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Solution Overview
Problem
Conventional aluminum brazing methods require flux to remove surface oxide films, which can lead to unstable brazing joints, environmental concerns, and increased costs due to the use of volatile solvents, and there is a need for improved clad aluminum alloys and brazing processes that can produce sound joints without flux.
Innovation Solution
Development of clad aluminum alloys with specific promoter agents such as magnesium, bismuth, antimony, strontium, sodium, and titanium in the cladding layers that interface with the oxide film to reduce or remove it, allowing for fluxless brazing by promoting wetting and flow of the molten cladding layer to form strong bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If flux-brazing methods are used with fluoride-based flux to remove oxide films, then oxide removal is achieved, but environmental harm and safety concerns increase due to volatile solvents and harmful etchants
Solution Approach 1:
The invention extracts and eliminates the harmful flux components (fluoride-based flux, volatile solvents, and harmful etchants) from the brazing process. By developing a fluxless brazing method using a molten aluminum-silicon alloy cladding layer, the patent removes the source of environmental pollution and safety hazards while maintaining effective oxide film removal through the chemical reaction between the cladding layer and oxide films at elevated temperatures
Solution Approach 2:
The invention changes the physical and chemical parameters of the brazing process by using a molten aluminum-silicon alloy cladding layer (with specific composition: 8-15 wt% Si, 0.1-1.0 wt% Fe, 0.01-0.5 wt% Cu, 0.01-0.3 wt% Mn, 0.01-0.2 wt% Mg) instead of traditional flux. The controlled atmosphere (nitrogen or argon) and temperature parameters (heating to melt the cladding layer) are optimized to achieve fluxless oxide removal and stable brazing joints
2Ease of manufacture
If flux is applied to remove oxide films during brazing, then oxide removal is achieved, but process complexity and cost increase due to cleaning/etching processes and flux coating requirements
Solution Approach 1:
The invention merges the oxide removal function and the brazing function into a single step by using the molten cladding layer to simultaneously remove oxide films and form the brazing joint. This eliminates the separate cleaning/etching process and flux application steps, simplifying the overall manufacturing process and reducing the number of process steps required
Solution Approach 2:
The cladding layer performs self-service by automatically removing oxide films through chemical reaction when molten, without requiring external flux application or separate cleaning processes. The aluminum-silicon alloy cladding layer reacts with oxide films on the base metal surfaces, spontaneously cleaning the surfaces and forming stable brazing joints in one integrated operation
3Reliability
If conventional aluminum alloys are used for brazing, then material availability is maintained, but brazing joint stability deteriorates due to oxide film barrier
Solution Approach 1:
The invention uses a composite structure consisting of a core aluminum alloy layer and an outer cladding layer with specific composition (8-15 wt% Si, 0.1-1.0 wt% Fe, 0.01-0.5 wt% Cu, 0.01-0.3 wt% Mn, 0.01-0.2 wt% Mg). This composite material design allows the cladding layer to remove oxide films and form stable brazing joints while the core layer maintains the mechanical properties of conventional aluminum alloys
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 use of these clad aluminum alloys enables the formation of stable, corrosion-resistant brazing joints without the need for flux, improving mechanical strength and reducing environmental impact by eliminating the use of volatile solvents and fluxes.
Implementation Method 1
the constituents in the cladding layer(s) penetrate the oxide film of a metal part to be joined to break or remove the surface oxide film
Implementation Method 2
promoting wetting and flow of the molten cladding layer to form strong bonds
Data Source
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AI summary
Provided are new aluminum alloys for use as one or more cladding layer(s) in clad aluminum alloy products for brazing applications. The cladding layer(s) include constituents that break and remove the oxide film on metal parts to be joined to produce high-strength brazing joints without the use of corrosive flux. Also provided herein are corrosion-resistant aluminum sheet packages including one or more of the aluminum alloy cladding layer(s) and an aluminum alloy core.