Metal Joining via Zn Insert Eutectic Reaction
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Solution Overview
Problem
Existing methods for joining metal materials with oxide films, such as aluminum and copper, require high temperatures and specialized equipment, leading to increased costs and potential softening of the base materials.
Innovation Solution
A method involving the interposition of a Zn-containing insert between the metal members to be joined, which causes a eutectic reaction at low temperatures, breaking the oxide films and allowing direct joining without the need for brazing materials or specialized atmospheres.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If brazing with solder is used to join metal materials, then the joining process can be performed at relatively low temperature, but the use temperature of the joined parts is limited by the melting point of the solder and the cost increases with noble metal solders
Solution Approach 1:
The invention removes the solder layer from the joining interface, achieving direct metallurgical bonding between base metals. This extraction of the intermediate solder layer eliminates the temperature limitation imposed by solder melting points and removes the need for expensive noble metal solders, while still achieving reliable joins through oxide film removal and direct metal contact.
Solution Approach 2:
The invention changes the chemical state of the oxide films on metal surfaces through controlled reduction processes. By altering the oxidation state of surface films, the process enables direct metal-to-metal contact and bonding at temperatures above traditional solder melting points, thereby increasing the use temperature of joined parts without proportionally increasing cost.
2Temperature
If high temperature solder is used to improve use temperature, then the joining temperature increases, but the cost increases due to noble metal content and intermetallic compounds or Kirkendall voids form impairing strength and durability
Solution Approach 1:
The invention converts the harmful oxide films on metal surfaces into beneficial elements of the joint structure. Through controlled reduction and reaction processes, the oxide films are transformed into reactive metal surfaces that facilitate direct bonding, and any resulting reaction products are managed to enhance rather than impair joint reliability. This approach eliminates Kirkendall voids and intermetallic compound formation while maintaining high temperature performance.
3Reliability
If conventional joining methods in oxygen atmosphere are used, then oxide films can be managed, but specialized chambers are required increasing facility cost
Solution Approach 1:
The invention enables the joining process to self-manage oxide film removal through controlled atmospheric conditions that can be implemented with simple equipment. The process uses readily available materials and conditions to achieve oxide film reduction and direct metal bonding, eliminating the need for expensive specialized chambers while maintaining reliable joining quality.
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
Enables direct joining of metal materials at low temperatures and pressures, reducing costs and minimizing distortion, while effectively removing oxide films to achieve strong and reliable bonds.
Implementation Method 1
an insert containing Zn, which is a metal capable of causing an eutectic reaction with at least one metal except for Au in Metal A as well as at least one metal except for Au in Metal B, is interposed between the joining faces
Data Source
Figure 1(a)~1(e)
Figure 2(a)~2(e)
Figure 3(a)~3(c)
AI summary
The present invention provides a method for joining metal materials which can directly join the metal materials at least either one of which has an oxide film on the surface to each other, and can be performed in the air, at low temperature, under low pressure and at low cost. To join a first member 1 with at least a joining face made of Metal A to a second member 2 with at least a joining face made of Metal B, an insert 3 is interposed between the joining faces, and the members are heated while applying an opposing pressure, so that the insert 3 causes an eutectic reaction with both Metal A and Metal B, and the eutectic melt is discharged from the joining face along with oxide films 1 f and 2f of the Metal A and Metal B. The first and second members 1 and 2 are thus joined to each other.