Dissimilar Metal Joining With Oxide Film Anchoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for joining metal members with different melting points, such as aluminum and magnesium alloys, often result in insufficient joining strength due to the formation of brittle intermetallic compounds at the interface, which is caused by the high temperature of the molten magnesium alloy breaking the oxide film on the aluminum alloy surface during die casting.
Innovation Solution
A method involving the use of an injection molding apparatus where a first metal member with a formed oxide film and unevenness is injected with a second metal material in a semi-molten or molten state, ensuring the temperature difference is less than or equal to 30°C, preventing the oxide film from breaking and promoting an anchor effect for enhanced joining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a second metal material is injected in a fully molten state at high temperature, then the filling ability and molding speed are improved, but the oxide film on the first metal member breaks and intermetallic compounds form reducing joining strength
Solution Approach 1:
The patent changes the temperature parameter of the second metal material from high temperature (fully molten) to low temperature (semi-molten or just above liquidus temperature, within 30°C). This parameter change allows the oxide film to remain intact while still achieving proper filling and joining strength of 30 MPa or more
Solution Approach 2:
The patent creates a composite structure at the interface between the first metal member and the second metal member, where the oxide film remains intact and unevenness is preserved. This composite interface structure prevents intermetallic compound formation while maintaining strong joining
2Temperature
If a melting furnace is used to heat the second metal material to high temperature, then the metal material achieves liquidus temperature for injection, but sludge is generated and entrapment defects occur
Solution Approach 1:
The patent changes the heating temperature parameter to be just above the liquidus temperature (within 30°C) rather than using high temperature melting. This eliminates sludge generation while still achieving the necessary molten state for injection molding
Solution Approach 2:
The patent extracts and eliminates the melting furnace from the process entirely, replacing it with an injection molding apparatus that can heat and inject the metal material in a single step, thereby removing the source of sludge generation
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 approach achieves a joining strength of 30 MPa or higher by preventing the formation of intermetallic compounds and reducing defects like gas entrapment and shrinkage cavities, while eliminating the need for a melting furnace and minimizing sludge entrapment.
Implementation Method 1
promoting an anchor effect for enhanced joining strength
Implementation Method 2
an oxide film covering the unevenness is formed thereover... preventing the oxide film from breaking
Data Source
AI summary
According to an embodiment, a method for manufacturing a joined metal member includes: disposing a first metal member inside a mold of an injection molding apparatus, the first metal member being made of a first metal material, unevenness being formed over a surface of the first metal member, and an oxide film being formed so as to cover the unevenness; and injecting a second metal material into the mold, and thereby molding a second metal member and joining the second metal member to the first metal member, the second metal material being, when it is injected into the mold, in a semi-molten state, or in a molten state in which a difference between a temperature of the second metal material and a liquidus temperature thereof is smaller than or equal to 30° C.