Oxide Superconductor Wire Grain Structure for Tensile Crack Resistance

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Solution Overview

Problem

Oxide superconducting wires suffer from deteriorating superconducting characteristics due to cracks caused by excessive tensile stress, as the oxide superconducting layer is less susceptible to elongation deformation than the metal substrate, leading to increased resistance.

Innovation Solution

The oxide superconducting wire is designed with a tape-shaped metal substrate made of a nickel alloy, featuring an average crystal grain size of 3.08 µm or more and a standard deviation of 2.32 to 14.66 µm, which enhances the wire's ability to withstand tensile stress without significant deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the metal substrate has high elongation deformation capability, then the oxide superconducting layer is prone to cracks under tensile stress, but if the metal substrate has low elongation deformation capability, then the overall flexibility and processability of the wire deteriorates

Engineering Contradiction:
Improvetensile resistance of metal substrateVSAvoidsuperconducting characteristics stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the crystal grain size parameter of the metal substrate to a specific range (3.08 μm or more and equal to or less than the thickness) to optimize the balance between elongation deformation capability and tensile resistance, preventing oxide superconducting layer cracks while maintaining wire flexibility

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure with controlled crystal grain distribution in the metal substrate, combining regions with different crystal grain sizes to achieve both sufficient elongation deformation capability and high tensile resistance, preventing oxide layer cracking

Inventive Principle:
Principle #40Composite materials

2Strength

If the average crystal grain size is increased to improve tensile resistance, then the recrystallization progresses and elongation deformation capability decreases, but if the average crystal grain size is decreased, then the tensile resistance is insufficient

Engineering Contradiction:
Improvetensile resistanceVSAvoidelongation deformation capability
Core Design Contradiction:
StrengthVSLength of moving object

Solution Approach 1:

The patent optimizes the average crystal grain size parameter within a specific range (3.08 μm or more and equal to or less than the thickness) to achieve the optimal balance between tensile resistance and elongation deformation capability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent controls the crystal grain size distribution locally within the metal substrate, creating a non-uniform microstructure where crystal grain size varies in different regions to simultaneously provide high tensile resistance and sufficient elongation deformation capability

Inventive Principle:
Principle #3Local 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

The design ensures high tensile resistance and maintains superconducting characteristics even under tensile stress, with an allowable strain amount in LN2 exceeding 0.40%, reducing the likelihood of cracks in the oxide superconducting layer.

Implementation Method 1

an average crystal grain size of the metal substrate is 3.08 μm or more and is equal to or less than a thickness of the metal substrate

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

standard deviation of a crystal grain size of the metal substrate is in a range of 2.32 to 14.66 μm

Methodology Applied
Scientific EffectCrystal grain boundary strengthening: Grain Boundary Strengthening

Implementation Method 3

superconducting characteristics are less likely to deteriorate even when a tensile stress is applied

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentEP4611007A1Oxide superconductor wire material, superconductor coil, and superconductor
Publication Date: 2025.09.03 FUJIKURA LTD
  • EP4611007A1 patent drawingFigure 1~2
  • EP4611007A1 patent drawingFigure 3~4A
  • EP4611007A1 patent drawingFigure 4B~4C

AI summary

An oxide superconducting wire includes a tape-shaped metal substrate made of a nickel alloy, an intermediate layer laminated on the metal substrate, and an oxide superconducting layer laminated on the intermediate layer, in which an average crystal grain size of the metal substrate is 3.08 µm or more and is equal to or less than a thickness of the metal substrate.