Aluminum Joining with Interlayer Sheet for Low-Temperature Bonding
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Solution Overview
Problem
Conventional methods for joining aluminum metal members, such as brazing and welding, face challenges including positional accuracy issues, corrosion, brittleness, and high energy requirements, while solid-phase diffusion joining struggles with oxide films that require increased pressure and temperature, leading to deformation.
Innovation Solution
A method involving the use of a sheet with an organic acid metal salt film, made from zinc, copper, or magnesium, sandwiched between the joining surfaces of aluminum members, which reduces the joining temperature and pressure needed, enhancing joining strength and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If brazing is used to join aluminum members, then joining strength is improved, but positional accuracy deteriorates and intermetallic compound formation causes brittleness
Solution Approach 1:
A sheet made of zinc, copper, or magnesium is introduced as an intermediary material between the aluminum members to be joined. This intermediate sheet facilitates the joining process by enabling solid-phase diffusion bonding while preventing direct contact between aluminum surfaces, thereby avoiding the formation of brittle intermetallic compounds and maintaining positional accuracy.
Solution Approach 2:
The joining method employs solid-phase diffusion bonding parameters (temperature and pressure) that are lower than conventional brazing parameters. By controlling the temperature to be below the melting point of aluminum and applying appropriate pressure, the process achieves strong joints without melting the base metal, thus preserving positional accuracy and preventing intermetallic compound formation.
2Manufacturing precision
If solid-phase diffusion joining is used to avoid melting and deformation, then manufacturing precision is improved, but oxide films on metal surfaces prevent effective joining
Solution Approach 1:
The sheet of zinc, copper, or magnesium is prepared in advance and positioned between the aluminum members before the joining process. This preliminary placement ensures that the intermediate sheet is already in position to prevent oxide film formation and facilitate diffusion bonding when heating and pressure are applied.
Solution Approach 2:
The intermediate sheet serves dual functions: it prevents oxide film formation on the aluminum surfaces by acting as a barrier, and it facilitates diffusion bonding by providing a metallurgically compatible interface for solid-phase joining, thereby achieving both strong joints and high precision.
3Strength
If increased pressure and temperature are applied to break oxide films, then joining strength is improved, but deformation increases
Solution Approach 1:
The intermediate sheet of zinc, copper, or magnesium prevents direct oxide film formation on the aluminum surfaces. This eliminates the need to apply high pressure to break through oxide films, as the intermediate material provides a clean, reactive surface for diffusion bonding, thereby achieving strong joints with minimal deformation.
Solution Approach 2:
The use of an intermediate sheet allows the joining process to proceed at lower pressures compared to direct solid-phase diffusion joining of aluminum. The intermediate material reduces the energy barrier for bonding, enabling effective joining at parameter levels that minimize thermal and mechanical deformation of the base metal.
4Strength
If brazing filler metal is melted to join aluminum members, then joining strength is improved, but harmful fluoride flux and corrosion problems occur
Solution Approach 1:
The sheet of zinc, copper, or magnesium serves as an intermediary that enables joining without requiring flux. The intermediate material creates a metallurgically compatible interface that facilitates diffusion bonding purely through thermal and mechanical energy, eliminating the need for harmful fluoride-based flux and subsequent corrosion issues.
Solution Approach 2:
The chemical process of flux-based brazing is replaced with a physical solid-phase diffusion process. Instead of using chemical reactions between flux and metal surfaces to enable joining, the method relies on direct atomic diffusion across the intermediate sheet interface, driven by temperature and pressure, thereby eliminating harmful chemical substances.
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
This method achieves high joining strength at lower temperatures and pressures, reducing deformation and energy consumption, and allows for the joining of aluminum members with complex shapes, improving positional accuracy and recyclability.
Implementation Method 1
a solid-phase diffusion joining method is a method of heating and pressurizing the metal members to thereby join the metal members without melting the matrix
Implementation Method 2
the sheet-like member is made of a material (such as copper, zinc, silver, a copper alloy, a zinc alloy, or a silver alloy, or silicon) that generates an eutectic reaction with aluminum
Implementation Method 3
it is proposed that the joining surfaces of copper is treated with an oxide film removing liquid formed of an organic acid before performing solid-phase joining
Implementation Method 4
a method of heating and pressurizing the metal members to thereby join the metal members without melting the matrix and without causing noticeable deformation in solid-phase state
Implementation Method 5
a method of heating and pressurizing the metal members to thereby join the metal members
Data Source
Figure 1~3
Figure 4A~4B
Figure 5A~5B
AI summary
To provide a method for joining metal members, in which joining can be performed at relatively lower temperature, and deformation caused when joining the metal members can be reduced. The present invention includes a step of joining a plurality of metal members with a sheet sandwiched between the joining surfaces of the plurality of metal members, wherein the sheet is obtained by forming an organic acid metal salt film on the surface of a metal sheet; wherein aluminum or an aluminum alloy is used as the metal members, and a sheet made of any one of zinc, copper and magnesium is used as the metal sheet.