Copper Alloy Diffusion Bonding with Oxide-Controlled Aging

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Solution Overview

Problem

Existing methods for bonding copper alloys, such as diffusion bonding, struggle to achieve high bonding strength and texture equal to the base material, especially when subjected to solution annealing and aging treatment, 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, ensuring a predetermined flatness and surface roughness of the bonding surfaces, removing the oxide film, and performing diffusion bonding followed by solution annealing and aging treatment to achieve a bonding interface with minimal or no oxide film, thereby securing extremely high bonding strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If diffusion bonding is performed on copper alloy with strong oxide film, then bonding process can be completed, but bonding strength is insufficient and cannot withstand solution annealing and aging treatment

Engineering Contradiction:

Improvebonding strengthVSAvoidwithstand thermal shock and dimensional fluctuation

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the copper alloy, specifically limiting Be content to 0.7% or less and controlling Ni and Co content to 2.0% or less each. This parameter optimization prevents excessive oxide formation while maintaining age-hardenability, enabling the bonding interface to withstand solution annealing and aging treatment without failure.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary oxide film removal from the bonding surfaces before diffusion bonding. This preliminary action eliminates the strong oxide film that would otherwise prevent adequate bonding strength and cause failure during subsequent thermal treatments, allowing the bonding interface to achieve strength comparable to the base material.

Inventive Principle:

Principle #10Preliminary action

2Strength

If oxide film is removed before bonding, then bonding strength improves, but oxide film reforms during temperature increase under high vacuum

Engineering Contradiction:

Improvebonding strengthVSAvoidoxide film reformation

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent optimizes the alloy composition parameters to control oxide formation tendency. By limiting Be to 0.7% or less and Ni/Co to 2.0% or less each, the alloy forms minimal oxide during vacuum heating, preventing re-oxidation of the bonding surface while maintaining the ability to form strong bonds through diffusion bonding.

Inventive Principle:

Principle #35Parameter changes

3Strength

If beryllium content is increased to achieve high strength, then tensile strength improves, but oxide film becomes stronger and更难 to remove

Engineering Contradiction:

Improvetensile strengthVSAvoidoxide film removal difficulty

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent optimizes the Be content parameter to 0.7% or less, which is sufficient to provide age-hardenability and high tensile strength after aging treatment, while being low enough to prevent formation of strongly adherent oxide films that are difficult to remove. This parameter optimization balances strength requirements with manufacturability.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If diffusion bonding is performed to achieve bonding, then bonding is completed, but bonding interface texture and strength are inferior to base material

Engineering Contradiction:

Improvebonding process completionVSAvoidbonding interface texture and strength equality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent optimizes alloy composition parameters (Be≤0.7%, Ni≤2.0%, Co≤2.0%) to enable the bonding interface to undergo solution annealing and aging treatment uniformly with the base material. This results in the bonding interface achieving the same texture and strength as the base material, eliminating the weakness typically associated with bonded joints.

Inventive Principle:

Principle #35Parameter changes

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 described method enables the production of a copper alloy bonded body with extremely high bonding strength, capable of withstanding severe thermal shock and dimensional fluctuations, and maintaining hydrogen-embrittlement resistance.

Implementation Method 1

etching treatment for removing an oxide film

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 2

diffusion bonding

Methodology Applied

Scientific EffectDiffusion bonding: Diffusion Welding

Implementation Method 3

solution annealing

Methodology Applied

Scientific EffectSolution annealing: Annealing

Implementation Method 4

an aging treatment

Methodology Applied

Scientific EffectAging treatment:

Data Source

PatentUS12337407B2Copper alloy assembly and production method therefor

Publication Date: 2025.06.24 NGK INSULATORS LTD

AI summary

A copper alloy bonded body composed of a plurality of members made of an age-hardenable copper alloy, the members diffusion-bonded to one another. The copper alloy bonded body has undergone solution annealing and an aging treatment, the content of beryllium in the age-hardenable copper alloy is 0.7% by weight or less, and (i) a bonding interface between the members has disappeared and/or (ii) a bonding interface between the members remains, and an oxide film at the bonding interface has a thickness of 0 nm or more and 5.0 nm or less.