Age-Hardenable Copper Bonding for Thermal Shock Durability
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Solution Overview
Problem
Existing diffusion bonding methods for copper alloys struggle to achieve high bonding strength, especially when subjected to solution annealing and aging treatments, due to strong oxide films and re-oxidation during the bonding process.
Innovation Solution
Selectively using an age-hardenable copper alloy with a beryllium content of 0.7% by weight or less, finishing the bonding surfaces to a predetermined flatness, removing the oxide film, and performing diffusion bonding followed by homogenization treatment, solution annealing, and aging treatment to achieve a bonding interface with a discontinuous region ratio of 3.5% or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If diffusion bonding is performed on copper alloy in a similar step to stainless steel, then bonding is achieved, but bonding strength is insufficient and cannot withstand solution annealing and aging treatment
Solution Approach 1:
The patent changes the bonding temperature parameter to 900°C or higher, which is specific to copper alloy diffusion bonding. This temperature parameter change enables sufficient bonding strength that can withstand subsequent solution annealing and aging treatment, resolving the contradiction between achieving bonding and maintaining bonding strength under thermal processing.
Solution Approach 2:
The patent applies preliminary action by removing oxide films from the copper alloy surfaces before diffusion bonding. This preliminary oxide removal ensures that the bonding interface is clean and free from oxidation during the bonding process, enabling strong bonding that can survive subsequent thermal treatments.
2Ease of manufacture
If oxide film is removed by simple pressure reduction and temperature increase, then bonding process is simplified, but oxide film is not effectively removed and re-oxidation occurs
Solution Approach 1:
The patent uses an inert atmosphere (vacuum or inert gas) during the diffusion bonding process to prevent re-oxidation of the copper alloy surfaces. This inert environment maintains the cleanliness of the bonding interface while allowing the bonding process to proceed, effectively removing the oxide film problem without complicating the manufacturing process.
Solution Approach 2:
The patent changes the temperature parameter to 900°C or higher, which is sufficient to remove oxide films from copper alloy surfaces through thermal decomposition. This temperature parameter change effectively removes oxide films while maintaining process simplicity.
3Use of energy by moving object
If diffusion bonding is performed at lower temperature, then energy consumption is reduced, but bonding strength is insufficient for high-pressure hydrogen applications
Solution Approach 1:
The patent optimizes the bonding temperature parameter to 900°C or higher, which is the minimum temperature required to achieve sufficient bonding strength in copper alloys. This parameter setting ensures that the bonding strength is adequate for high-pressure hydrogen applications while minimizing energy consumption by not using excessively high temperatures.
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 results in a copper alloy bonded body with extremely high bonding strength, capable of withstanding severe thermal shock and dimensional fluctuations, while maintaining high thermal conductivity and hydrogen-embrittlement resistance.
Implementation Method 1
a plurality of members made of an age-hardenable copper alloy, the members diffusion-bonded to one another
Implementation Method 2
a material including tensile strength that is bearable to high pressure and a thermal conductive property that enables efficient cooling
Data Source
AI summary
There is provided a copper alloy bonded body composed of members made of an age-hardenable copper alloy, the members diffusion-bonded to one another, wherein a bonding interface between the members remains. In the bonded body, the content of beryllium in the age-hardenable copper alloy is 0.7% by weight or less, and, in a laser microscope image of a section including the bonding interface, a ratio of a total length of a line segment corresponding to a discontinuous region relative to an entire length of a bonding interface line defined along the bonding interface and a position where the bonding interface was present is 3.5% or more. The discontinuous region is defined as a region where, when a plurality of perpendicular lines is drawn with respect to the bonding interface line at a pitch of 5 μm, three or more adjacent perpendicular lines do not intersect with the remaining bonding interface.