Aluminum Brazing Sheet Processing for Flux-Free Brazeability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing brazing methods for aluminum materials face issues such as flux residue, low productivity, and poor brazeability in vacuum-brazing, and flux-free methods suffer from poor brazeability due to the chemical compositions of core and filler materials.
Innovation Solution
A manufacturing method involving a clad slab with a core-material slab and a filler-material slab of Al—Si—Mg series alloy, followed by hot rolling, cold rolling, and etching with an inorganic acid etchant to enhance brazeability in an inert-gas atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flux-brazing method is used, then brazing can be performed easily, but flux and residue adhere to the surface causing quality problems and requiring additional acid-washing process
Solution Approach 1:
The invention extracts and eliminates the flux component from the brazing process by developing a flux-free brazing sheet with core material and filler material that enable brazing without flux, thereby removing the source of flux residue contamination
Solution Approach 2:
The invention creates an inert environment by using specific alloy compositions (Al-Si-Mg series) that prevent oxidation and enable brazing in inert-gas atmosphere without requiring flux, thus avoiding flux residue problems
2Object-affected harmful factors
If vacuum-brazing method is used, then flux residue problems are avoided, but productivity decreases and equipment cost increases
Solution Approach 1:
The brazing sheet is designed with self-protective properties through specific alloy compositions that enable effective brazing in inert-gas atmosphere without requiring vacuum conditions, allowing standard furnaces to be used and maintaining high productivity
Solution Approach 2:
The invention changes the chemical composition parameters of the brazing sheet (using Al-Si-Mg series alloys with specific ranges of Si: 3-13 mass%, Mg: 0.1-2 mass%) to enable flux-free brazing in inert-gas atmosphere, achieving both flux residue elimination and high productivity
3Ease of manufacture
If conventional brazing sheet composition is used in flux-free brazing, then brazing can be performed without flux, but brazeability deteriorates
Solution Approach 1:
The invention optimizes the chemical composition parameters of both core material and filler material, specifically using Al-Si-Mg series alloy with Si: 3-13 mass%, Mg: 0.1-2 mass%, to achieve excellent brazeability in flux-free brazing conditions
Solution Approach 2:
The invention creates a composite structure with core material and filler material having different but complementary compositions, where the filler material (Al-Si-Mg series) specifically enhances brazeability by breaking down oxide films while the core material provides structural integrity
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 method produces a brazing sheet with improved brazeability and reduced flux residue, maintaining high productivity and quality without the need for flux, while avoiding the drawbacks of vacuum-brazing.
Implementation Method 1
a surface of the clad sheet is etched using a liquid etchant that includes an inorganic acid
Implementation Method 2
These metal elements act to break down oxide films present on the brazing sheet itself and on the surface of the opposing material to be joined with the brazing sheet during brazing
Data Source
AI summary
A brazing-sheet manufacturing method includes superposing a core-material slab on or adjacent to at least one surface of a filler-material slab to form a clad slab, the core-material slab being composed of an aluminum material and the filler-material slab being composed of an Al—Si—Mg series alloy. Then, the clad slab is hot rolled to form a clad sheet having a core material layer composed of the aluminum material of the core-material slab and a filler material layer composed of the Al—Si—Mg series alloy of the filler-material slab. Then, the clad sheet is subjected to one or more passes of cold rolling. Either between cold-rolling passes or after the completion of the cold rolling, a surface of the clad sheet is etched using a liquid etchant that includes one or more inorganic acids. The liquid etchant does not contain fluorine atoms.