Copper-Sheathed Nb-Sn Superconductor Assembly With Diffusion Barrier
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Solution Overview
Problem
Current methods for manufacturing superconductors, such as the rod-in-tube and tubular methods, are costly due to high niobium alloy barrier requirements and limited current carrying capacity, and they face challenges with the availability and cost of niobium alloy tubing.
Innovation Solution
A method involving a metal assembly precursor formed within a hollow copper support element, where conductor elements with unreacted Nb are positioned around a Sn core, with inner and outer interstitial elements, and a diffusion blocking layer, which is then reduced and heat-treated to produce a superconductor, allowing for improved current carrying capacity and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rod-in-tube method is used with thick niobium barrier to prevent copper contamination, then superconductor purity is improved, but manufacturing cost increases significantly
Solution Approach 1:
A thin diffusion barrier layer of tantalum (Ta) or niobium-tantalum alloy is introduced as an intermediary between the copper matrix and the superconducting filaments. This intermediate layer effectively prevents copper diffusion into the superconductor while being much thinner and less expensive than the thick pure niobium barriers used in conventional rod-in-tube methods.
Solution Approach 2:
The invention changes the material composition parameters of the diffusion barrier from pure niobium to tantalum or niobium-tantalum alloys, and reduces the barrier thickness parameter. This parameter change achieves the same protective function at lower cost and with improved processability.
2Ease of manufacture
If tubular method is used with niobium alloy tubing to reduce cost, then manufacturing cost decreases, but current carrying capacity is limited due to reaction control requirements
Solution Approach 1:
The diffusion barrier layer serves as an intermediary that controls the reaction between copper and superconducting materials during heat treatment. This controlled reaction environment enables higher current carrying capacity by allowing more complete formation of the superconducting phase without excessive copper contamination.
Solution Approach 2:
The invention uses composite niobium-tantalum alloy materials for the diffusion barrier, combining the benefits of both metals: niobium provides superconducting properties and tantalum provides oxidation resistance and controlled diffusion characteristics, achieving optimal performance for high current carrying capacity.
3Reliability
If double extrusion and multi-step drawing process are used in rod-in-tube method to achieve high filament count, then superconductor performance is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention merges the barrier layer formation and filament assembly steps into a single integrated process. The diffusion barrier is applied as a thin conformal layer on the copper substrate before filament placement, eliminating the need for separate barrier fabrication and assembly steps required in conventional rod-in-tube methods.
Solution Approach 2:
The invention uses thin film diffusion barriers that can be conformally deposited on complex substrate geometries. This thin film approach simplifies the manufacturing process compared to thick barrier materials, enabling easier handling and reduced process complexity while maintaining effective diffusion protection.
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 results in a superconductor with enhanced performance and reduced production costs, capable of achieving nearly equivalent current density to the rod-in-tube method while being more cost-effective and producible in longer lengths, with improved processability and flexibility.
Implementation Method 1
The reduced metal assembly can be reaction heat treated so that the unreacted Nb undergoes a phase transformation to a reacted superconductor
Implementation Method 2
The metal assembly precursor can include a diffusion blocking layer between the plurality of conductor elements and the hollow copper support element
Implementation Method 3
The metal assembly precursor can be reduced via cold drawing to produce a reduced metal assembly
Data Source
AI summary
A method for manufacturing a superconductor is described. A metal assembly precursor can be formed within a hollow copper support element. Forming the metal assembly precursor within a hollow copper support element by positioning a plurality of conductor elements about a core including Sn to provide a first plurality of inner interstitial spaces between the plurality of conductor elements between the core and conductor elements and a second plurality of outer interstitial spaces between the hollow copper support element and the core, the plurality of conductor elements including unreacted Nb. The metal assembly precursor can be reduced via cold drawing to produce a reduced metal assembly. The reduced metal assembly can be reaction heat treated so that the unreacted Nb undergoes a phase transformation to a reacted superconductor.