Nb3Sn Superconducting Wire Bar Design for High Magnetic Fields
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Solution Overview
Problem
The challenge in manufacturing superconducting wires based on Nb3Sn lies in their low mechanical features, which limit the use of traditional deformation methods, and the formation of brittle intermetallic compounds during the manufacturing process, leading to reduced deformability and current-carrying capability, especially in high magnetic fields above 12 T.
Innovation Solution
A bar design for superconducting composite wire comprising a copper case with a tin-bearing rod at its center, surrounded by niobium-bearing rods in a copper shell, where Nb-Ti alloy fibers are strategically placed within a niobium or niobium alloy matrix at a distance from the copper shell to prevent the formation of intermetallic compounds, ensuring uniform titanium doping and high current-carrying capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Nb-Ti alloy rods are placed around the tin core in direct contact with the copper coating, then the current-carrying capability is improved through titanium doping, but brittle Ti2Cu intermetallic compounds form during heat treatment, reducing deformability and causing wire breakage
Solution Approach 1:
A niobium intermediate layer is introduced between the Nb-Ti alloy rods and the copper coating. This intermediary layer prevents direct contact between titanium and copper, blocking the formation of brittle Ti2Cu intermetallic compounds during heat treatment, while still allowing titanium diffusion into the superconducting matrix for doping.
Solution Approach 2:
The structure is segmented into distinct functional layers: the copper coating, the niobium intermediate layer, and the Nb-Ti alloy rods. This segmentation isolates the titanium-containing regions from direct copper contact, preventing harmful intermetallic formation while maintaining the desired doping effect in the superconducting matrix.
2Ease of manufacture
If traditional deformation methods are used to manufacture Nb3Sn superconducting wires, then the manufacturing process is simplified, but the low mechanical properties of Nb3Sn compound cause multiple breaks and make wire production difficult
Solution Approach 1:
The bar structure is preliminarily designed with Nb-Ti alloy rods positioned at specific distances from the copper coating, and the superconducting matrix is pre-formed with proper mechanical support. This preliminary configuration ensures that during subsequent drawing and deformation operations, the wire maintains structural integrity and resists breaking.
Solution Approach 2:
The invention uses a composite bar structure combining copper, niobium, Nb-Ti alloy, and tin in a specific arrangement. This composite design leverages the mechanical strength of copper and niobium to support the brittle Nb3Sn superconducting compound during deformation, enabling traditional drawing methods to succeed.
3Reliability
If Nb-Ti alloy rods are placed close to the copper coating to maximize titanium doping, then the current-carrying capability increases, but uneven doping occurs and Ti2Cu formation reduces the uniformity of the superconducting layer
Solution Approach 1:
The niobium intermediate layer provides a controlled local environment for titanium diffusion. It allows titanium to diffuse into the superconducting matrix at a controlled rate and distance, ensuring uniform doping throughout the matrix while preventing excessive titanium concentration near the copper interface that would cause non-uniformity.
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 design enhances the current-carrying capability of the superconducting composite wire in magnetic fields above 12 T by maintaining the wire's deformability and preventing the formation of brittle compounds, resulting in a uniform superconducting layer with improved critical current density.
Implementation Method 1
the heat treatment process performed during the wire manufacture will lead to the formation of a brittle intermetallic compound Ti2Cu
Implementation Method 2
doping of niobium fiber material with titanium in an amount of 1-2 wt% leads to a significant increase in the critical current density
Data Source
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AI summary
The invention relates to the field of electrical engineering and the creation of long composite wires based on superconducting compounds for use in the manufacture of electrical equipment. A blank for manufacturing a superconducting composite wire based on Nb3Sn consists of a copper jacket, inside which a copper-containing matrix is disposed, at the centre of which lies a rod containing tin, around which a plurality of niobium-containing rods are arranged in a copper-containing casing, wherein the copper-containing matrix is surrounded by a diffusion barrier, and a niobium-containing rod is comprised of a composite containing a matrix which is made of niobium or an alloy thereof and which is reinforced with filaments made of a Nb-Ti alloy, which are arranged at a distance of not less than one average size of a Nb-Ti alloy filament to the boundary of the copper-containing casing, wherein the distance between said filaments is not less than one average size of a Nb-Ti alloy filament. The technical result is high current carrying capability in a superconducting composite wire based on Nb3Sn in magnetic fields with an induction greater than 12 T.