Superconducting Wire MOD Intermediate Layer

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Solution Overview

Problem

The manufacturing of superconducting wires is hindered by the high costs and reduced yield due to substrate polishing, and the improved surface smoothness of the substrate reduces adhesive strength, limiting the achievement of high critical current properties.

Innovation Solution

A superconducting wire with a substrate having a surface roughness of 10 nm to 18 nm, featuring a first intermediate layer with thin coating films deposited using the MOD method and a second biaxially oriented intermediate layer, allowing for enhanced surface smoothness and adhesive strength without the need for substrate polishing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If substrate polishing is performed to improve surface smoothness, then the surface smoothness of the substrate is improved, but the adhesive strength between the substrate and intermediate layer decreases

Engineering Contradiction:
Improvesurface smoothnessVSAvoidadhesive strength
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The invention changes the parameter of substrate surface smoothness from the conventional requirement of high smoothness (Ra≤2nm) to a controlled roughness range (Ra=2nm to 5nm). This parameter change resolves the contradiction by showing that moderate roughness actually improves both adhesive strength and allows achievement of appropriate intermediate layer smoothness through the MOD method, eliminating the need for costly polishing while maintaining or improving adhesive properties

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention inverts the conventional approach by not attempting to make the substrate surface smoother, but rather by accepting a controlled roughness and using the MOD method to create a smooth intermediate layer anyway. This inversion resolves the contradiction by demonstrating that the intermediate layer's smoothness is determined by the deposition method rather than the substrate surface condition

Inventive Principle:
Principle #13The other way round (Inversion)

2Manufacturing precision

If substrate polishing is performed to improve surface smoothness, then the surface smoothness of the substrate is improved, but manufacturing costs increase and yield decreases

Engineering Contradiction:
Improvesurface smoothnessVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention extracts the substrate polishing step from the manufacturing process entirely. By demonstrating that the MOD method can produce an appropriately smooth intermediate layer on a moderately rough substrate, the invention removes the costly polishing operation, thereby reducing manufacturing costs and improving yield without sacrificing the required surface smoothness of the intermediate layer

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the expensive mechanical polishing process with a more economical approach using the MOD deposition method. The substrate serves as a temporary base that doesn't require high precision, allowing the use of simpler, cheaper substrate preparation methods while achieving the desired final surface quality through the deposition process itself

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

3Device complexity

If conventional deposition methods are used, then the deposition process is simple, but the surface smoothness of the intermediate layer cannot be higher than the substrate surface smoothness

Engineering Contradiction:
Improvedeposition process complexityVSAvoidintermediate layer surface smoothness
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The invention replaces mechanical deposition methods (such as sputtering or physical vapor deposition) with the MOD (Metal Organic Deposition) chemical deposition method. This substitution enables the formation of a smooth intermediate layer even on a moderately rough substrate, as the chemical deposition process fills in surface irregularities, achieving Ra≤2nm surface smoothness without requiring complex mechanical polishing equipment or processes

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 enables the deposition of an intermediate layer with appropriate surface smoothness, achieving high critical current properties while reducing manufacturing costs by eliminating the need for substrate polishing and maintaining high adhesive strength.

Implementation Method 1

The MOD method, which is a non-vacuum process

Methodology Applied
Scientific EffectMetal Organic Deposition:

Data Source

PatentEP2725586B9Superconducting wire
Publication Date: 2018.09.19 FURUKAWA ELECTRIC CO LTD
  • EP2725586B9 patent drawingFigure 1~2
  • EP2725586B9 patent drawingFigure 3
  • EP2725586B9 patent drawingFigure 4

AI summary

A superconducting wire is provided which allows an appropriate critical current property to be obtained while maintaining high adhesive strength based on smoothness of a substrate surface that can be achieved without mechanical polishing or the like. A first intermediate layer 21 is formed by coating a material solution on a substrate 10 with a maximum height roughness Rz of 10 nm or more. This improves surface smoothness of the first intermediate layer 21, improves orientation and smoothness of a second intermediate layer 22 formed on the first intermediate layer 21, and increases a critical current in an oxide superconducting layer 30. Furthermore, the first intermediate layer 21 is formed of a plurality of thin coating film layers 21i. The thin coating film layers 21i are deposited such that an uppermost thin coating film layer has a smaller film thickness than a lowermost thin coating film layer and/or a material solution used for the uppermost thin coating film layer has a lower viscosity than a material solution used for the lowermost thin coating film layer. This improves the surface smoothness of the first intermediate layer 21.