Compound Superconducting Wire Reinforcement Filaments
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Solution Overview
Problem
Existing superconducting wires for strong magnetic fields and nuclear fusion reactors face challenges in maintaining high strength and stability under electromagnetic forces and strain, particularly with reinforcement methods like CuNb alloys and Cu/Ti composites, which suffer from uniformity issues, wire breakage, and insufficient bending strain performance.
Innovation Solution
A compound superconducting wire design featuring reinforcement filaments of Nb, Ta, V, W, or Hf, with a stabilizing copper alloy layer, and a diffusion prevention layer, forming a reinforced superconducting wire structure that is strong against both tensile and bending strains, and maintains high residual resistivity ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a reinforcement consisting of CuNb alloy formed by in-situ method is used, then the superconducting wire strength is improved, but the uniformity in length direction deteriorates and wire breakage during processing occurs
Solution Approach 1:
The reinforcement is divided into multiple discrete filaments (e.g., 19 filaments) rather than using a monolithic CuNb alloy structure. Each filament is individually formed and then bundled, which distributes stress evenly along the length direction and prevents localized weakness that would cause non-uniformity and breakage during processing.
Solution Approach 2:
A Cu matrix is introduced as an intermediary material that surrounds and binds the reinforcement filaments. This Cu matrix acts as a buffer that distributes mechanical stresses uniformly across all filaments, preventing stress concentration and ensuring uniform strength properties along the wire length while maintaining high overall strength.
2Reliability
If the amount of copper wire composited with the superconducting wire is increased to secure conduction stability, then conduction stability is improved, but the current density per superconducting wire decreases
Solution Approach 1:
Copper is strategically placed only in specific locations where it is most needed - as a matrix surrounding the reinforcement filaments and as a stabilizing layer at the outer periphery. This localized copper distribution provides conduction stability and mechanical support exactly where stresses and electrical currents are most concentrated, while minimizing the total copper volume to preserve high current density in the superconducting core.
Solution Approach 2:
A multi-component composite structure is created combining superconducting filaments, reinforcement filaments, Cu matrix, and Cu stabilizing layer. Each component performs a specific function: the superconducting filaments carry current, the reinforcement filaments provide strength, the Cu matrix distributes stress and provides local conduction paths, and the outer Cu layer stabilizes the wire. This functional composite approach optimizes both conduction stability and current density.
3Strength
If Cu/Ti composite reinforcement is used, then the reinforcement strength is improved, but the bending strain performance deteriorates due to Cu-Ti compound formation
Solution Approach 1:
The Cu matrix serves as an intermediary that physically separates the reinforcement filaments from direct contact with each other and from the superconducting filaments. This matrix layer prevents harmful chemical reactions between different metal components while still allowing mechanical stress to be distributed uniformly, thereby maintaining high bending strain performance alongside high strength.
Solution Approach 2:
Instead of using Ti which forms brittle compounds, the invention uses readily formable Cu-based materials for the matrix and stabilizing layers. These Cu components are designed to be slightly softer and more ductile, acting as a sacrificial element that deforms first to protect the harder reinforcement filaments from bending damage, thereby improving overall wire flexibility and bending performance.
Data Source
AI summary
A compound superconducting wire 10 includes a reinforcement portion 12 and a compound superconductor 11. In the reinforcement portion 12, an assembly of plural reinforcement elements 4 are disposed. The reinforcement elements 4 each include plural reinforcement filaments 1 disposed in a stabilizer 2, and a stabilizing layer 3 at the outer periphery thereof. The reinforcement filaments 1 each mainly contain one or more metals selected from the group consisting of Nb, Ta, V, W, Mo, Fe, and Hf, an alloy consisting of two or more metals selected from the aforementioned group, or an alloy consisting of copper and one or more metals selected from the aforementioned group.