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Method for preparing magnesium diboride superconducting wire or strip by electron beam annealing

A technology of electron beam annealing and superconducting wire, which is applied in the manufacture/processing of superconductor devices, can solve the problems of increased oxidation degree of superconducting core and thickened interface layer, and achieves short annealing time, fast heating and cooling speed, The effect of high energy density

Active Publication Date: 2017-10-27
INST OF ELECTRICAL ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, the traditional sintering method under the protection of argon atmosphere is widely used, and the annealing time is generally more than ten minutes, but because the argon gas used as the protective atmosphere still contains a considerable amount of oxygen, it may cause Increased MgO content in samples during sintering
In addition, longer annealing time is also easy to cause too much MgB 2 The decomposition of the superconducting core, the thickening of the interface layer between the superconducting core and the casing, and the increase in the degree of oxidation of the superconducting core, etc.

Method used

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  • Method for preparing magnesium diboride superconducting wire or strip by electron beam annealing

Examples

Experimental program
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Effect test

Embodiment 1

[0026] Electron beam annealing was carried out on a self-made EBW-6 electron beam welding machine. The precursor was an unphased MgB2 wire with a diameter of 1 mm and a length of 10 mm, and the outer sheath was made of stainless steel.

[0027] 1. Put the unphased MgB2 wire precursor on the movable workpiece table in the sample chamber of the electron beam processing equipment, close the sample chamber and start the vacuum pump, when the vacuum degree in the sample chamber is higher than 1.0×10 -2 Pa, continue the operation of the next step;

[0028] 2. Select the electron beam acceleration voltage U as 5kV, the electron beam current I as 10mA, and the beam spot size Φ as 14mm, and the beam spot size completely covers the sample to be annealed;

[0029] 3. Use the moving workpiece table inside the welding machine to move the wire to be annealed to the position directly below the electron beam spot, and then start the electron beam annealing. The annealing time is 30 seconds; ...

Embodiment 2

[0031] Electron beam annealing is carried out on a self-made EBW-6 electron beam welding machine. The precursor is an unphased MgB2 wire with a diameter of 3 mm and a length of 10 mm, and the outer sheath is oxygen-free copper.

[0032] 1. Put the unphased MgB2 wire precursor on the movable workpiece table in the sample chamber of the electron beam processing equipment, close the sample chamber and start the vacuum pump, when the vacuum degree in the sample chamber is higher than 1.0×10 -2 Pa, continue the operation of the next step;

[0033] 2. Select the electron beam acceleration voltage U as 10kV, the electron beam current I as 8mA, and the beam spot size Φ as 14mm. The beam spot size can completely cover the sample to be annealed;

[0034] 3. Use the moving workpiece table inside the welding machine to move the wire to be annealed to the position directly below the electron beam spot, and then start the electron beam annealing. The annealing time is 120 seconds; wires, suc...

Embodiment 3

[0036] Electron beam annealing is carried out on a self-made EBW-6 electron beam welding machine. The precursor is an unphased MgB2 wire with a diameter of 2 mm and a length of 15 mm, and the outer sheath is iron.

[0037] 1. Put the unphased MgB2 wire precursor on the movable workpiece table in the sample chamber of the electron beam processing equipment, close the sample chamber and start the vacuum pump, when the vacuum degree in the sample chamber is higher than 1.0×10 -2 Pa, continue the operation of the next step;

[0038] 2. Select the electron beam acceleration voltage U as 60kV, the electron beam current I as 12mA, and the beam spot size Φ as 20mm, the beam spot size can completely cover the sample to be annealed;

[0039] 3. Use the moving workpiece table inside the welding machine to move the wire to be annealed to the position directly below the electron beam spot, and then start the electron beam annealing. The annealing time is 60 seconds; wires, such as figure...

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Abstract

The invention discloses a method for preparing magnesium diboride superconducting wire or strip by electron beam annealing. The method adopts electron beam to anneal the unphased MgB2 wire or strip precursor prepared by in-situ powder sleeve method in vacuum. Annealing, within the annealing time of several seconds to several minutes, the magnesium-boron mixed powder in the wire or strip precursor undergoes a chemical reaction to finally generate magnesium diboride superconducting wire or strip. Electron beam parameters and annealing time are determined according to different wire or strip precursor thickness and annealing temperature requirements during annealing, and the annealing of different diameter wires or strips is completed by precisely controlling the electron beam acceleration voltage, beam current and annealing time. The magnesium diboride superconducting wire or strip prepared by the invention has stable properties, fine and uniform crystal grains, uniform phase formation, and a transition temperature higher than 37K.

Description

technical field [0001] The invention relates to a preparation method of a magnesium diboride superconducting wire or strip, in particular to an unphased MgB2 wire or strip precursor prepared by an in-situ powder casing method, and the diboride is prepared by electron beam annealing Process for magnesium superconducting wire or strip. Background technique [0002] Since the discovery of magnesium diboride superconductors with a critical transition temperature of 39K by Akimitsu et al. in Japan in January 2001 (Nature 410 (2001) 63), scientists from various countries have conducted a lot of research on magnesium diboride superconductors. MgB2 superconductors have obvious advantages in the application of 20-30K and low field conditions, and also have broad application prospects in superconducting power and electronic devices. The currently reported preparation methods of MgB2 wire or strip include diffusion method, powder in tube (Powder In Tube) method, and continuous tube fo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L39/24
Inventor 孔祥东韩立李晓娜许壮桂漓江李艳丽张雪娜
Owner INST OF ELECTRICAL ENG CHINESE ACAD OF SCI
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