Copper Stabilizer Composition for Superconducting Wire RRR Recovery

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Solution Overview

Problem

Superconducting wires face issues with increased resistance and lattice defects due to deformation during processing, leading to decreased residual resistance ratio (RRR) and instability in high magnetic fields, necessitating a stabilizing material with low recrystallization temperature and high hardness.

Innovation Solution

A superconductivity stabilizing material composed of copper with additive elements Ca, Sr, Ba, or rare earth elements within specific concentration ranges, along with controlled impurity levels, to maintain a half-softening temperature below 200°C, Vickers hardness above 55 Hv, and RRR between 50 and 500, ensuring effective current diversion and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ultra-high purity copper is used to achieve low resistance at extremely low temperatures, then the residual resistance ratio (RRR) is improved, but the manufacturing process becomes extremely complicated and manufacturing costs increase significantly

Engineering Contradiction:
Improveresidual resistance ratio (RRR)VSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the purity parameter from ultra-high purity (99.9999% or more) to high purity (99.99% or more), and introduces additive elements (Ti, V, Nb, Ta, Zr, Hf, B, or Si) at controlled concentrations (0.001-100 ppm) to achieve the desired RRR without requiring extremely complex manufacturing processes

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite copper material system by combining high-purity copper with trace amounts of specific additive elements, where the additives work synergistically to reduce residual resistance while maintaining manufacturability, avoiding the need for ultra-high purity copper

Inventive Principle:
Principle #40Composite materials

2Strength

If the superconducting wire is subjected to substantial deformation during processing, then the mechanical strength is improved, but lattice defects such as dislocations increase and resistance may increase

Engineering Contradiction:
Improvemechanical strengthVSAvoidelectrical resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention changes the material's recrystallization behavior by introducing additive elements that lower the recrystallization temperature, allowing lattice defects from deformation to be eliminated through heat treatment without compromising mechanical strength

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention performs preliminary heat treatment to restore RRR after deformation processing, using the additive elements to enable recrystallization at controlled temperatures that remove dislocations while preserving the mechanically strengthened structure

Inventive Principle:
Principle #10Preliminary action

3Reliability

If high purity copper is used to reduce impurity elements, then the residual resistance ratio (RRR) is improved, but the manufacturing costs increase significantly

Engineering Contradiction:
Improveresidual resistance ratio (RRR)VSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The invention changes the compositional parameters from requiring ultra-high purity copper to using high-purity copper with controlled additive elements, achieving comparable or superior RRR at lower manufacturing costs by avoiding the expensive ultra-high purity copper production process

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses small, controlled amounts of inexpensive additive elements (0.001-100 ppm) to achieve the desired performance, replacing the need for expensive ultra-high purity copper while maintaining or improving RRR

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 material effectively suppresses resistance increases, maintains stability in high magnetic fields, and reduces manufacturing complexity and costs by optimizing impurity concentrations and additive element ratios, ensuring reliable current diversion and reduced frictional heat generation.

Implementation Method 1

the current flowing through the superconducting material is temporarily diverted to the superconductivity stabilizing material

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

Residual resistance ratio (RRR) is widely used as an indicator of electric resistance at extremely low temperatures

Methodology Applied
Scientific EffectElectrical resistance: Electrical Resistance

Implementation Method 3

it is necessary to restore the residual resistance ratio (RRR) by performing a heat treatment after the processing to sufficiently reduce lattice defects in the matrix as a recrystallized structure

Methodology Applied
Scientific EffectRecrystallization:

Implementation Method 4

at least one of additive elements selected from Ca, Sr, Ba, and rare earth elements in a range of 3 ppm by mass or more and 100 ppm by mass or less in total, with a remainder being Cu and unavoidable impurities

Methodology Applied
Scientific EffectCompound formation: Chemical Bonding

Data Source

PatentEP3705589B1Superconductivity stabilizing material, superconducting wire, and superconducting coil
Publication Date: 2025.08.06 MITSUBISHI MATERIALS CORP
  • EP3705589B1 patent drawingFigure 1~2
  • EP3705589B1 patent drawingFigure 3~4
  • EP3705589B1 patent drawingFigure 5A~5B

AI summary

A superconductivity stabilizing material used for a superconducting wire and which is formed of a copper material containing at least one of additive elements selected from Ca, Sr, Ba, and rare earth elements in a range of 3 ppm by mass or more and 100 ppm by mass or less in total, with a remainder being Cu and unavoidable impurities, in which the total concentration of the unavoidable impurities, excluding O, H, C, N, and S which are gas components, is 5 ppm by mass or more and 100 ppm by mass or less, the half-softening temperature thereof is 200°C or lower, the Vickers hardness thereof is 55 Hv or more, and the residual resistance ratio (RRR) thereof is 50 or more and 500 or less.