Oxide Superconducting Wire Precursor with Segmented Arch Filaments
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Solution Overview
Problem
Existing oxide superconducting wire production methods, such as the powder-in-tube method, face challenges in increasing critical current density due to limitations in crystal orientation and irregularities during the drawing and rolling processes, which reduce the wire's performance.
Innovation Solution
A precursor wire design featuring a center portion surrounded by concentrically arranged arch-shaped monofilamentary segments with a ribbon-shaped filament of oxide superconductor, covered in silver or silver alloy, which maintains uniform stress and orientation during diameter reduction, preventing sheath breakage and enhancing crystal alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a round or hexagonal monofilamentary wire with isotropic cross section is used, then the production process is simple, but the filament thickness prevents adequate crystal orientation and reduces critical current density
Solution Approach 1:
The wire cross-section is segmented into multiple regions with different functions: a central core region and peripheral regions containing flattened filaments. This segmentation allows the central core to provide structural support while the peripheral flattened filaments achieve adequate thickness for crystal orientation, thereby resolving the contradiction between manufacturing simplicity and critical current density
Solution Approach 2:
Different regions of the wire cross-section are given different properties: the central core has isotropic properties for easy manufacturing, while the peripheral regions have anisotropic flattened filament structures optimized for crystal orientation. This local differentiation allows each region to fulfill its specific function, achieving both ease of manufacture and high critical current density
2Reliability
If the number of monofilamentary wires is increased to reduce individual filament thickness, then crystal orientation improves, but the drawing process causes irregularities and sheath breakage
Solution Approach 1:
The wire adopts an asymmetric cross-sectional structure with a central core and peripheral flattened filaments. This asymmetric design allows the central core to bear the mechanical stress during drawing, protecting the peripheral filaments from damage while maintaining their flattened shape for adequate crystal orientation, thus resolving the contradiction between critical current density and drawing uniformity
3Ease of manufacture
If a thick filament is used, then the production process is simpler, but the crystal orientation ability is insufficient, reducing critical current density
Solution Approach 1:
The filament cross-section is changed from a thick isotropic shape to a flattened shape with extended dimensions. This dimensional change increases the surface area and aspect ratio of the filaments, enabling adequate crystal orientation along the wire axis while maintaining a manageable number of filaments, thus resolving the contradiction between manufacturing simplicity and critical current density
Data Source
AI summary
A precursor wire of an oxide superconducting wire includes a first sheath made of silver or silver alloy, a center portion in the first sheath, and a plurality of peripheral segments placed close to one another at the inside of the first sheath so as to surround the center portion. Each of the peripheral segments is formed as a monofilamentary segment that has an arch-shaped cross section and that includes a ribbon-shaped filament made of a precursor of an oxide superconductor and covered with a second sheath made of silver or silver alloy. The multiple peripheral segments are placed in a multilayer state in the form of concentric circles such that wide-width surfaces of the peripheral segments surround the center portion.