Preparation method of carbon-doped magnesium diboride superconducting tape

A superconducting tape, magnesium diboride technology, applied in the manufacture/processing of superconductor devices, boron/borides, metal borides, etc., can solve the problems of low density, high heat treatment temperature, difficult use and transportation, etc. Achieve the effect of increased critical current density, low heat treatment temperature, and good grain connectivity

Inactive Publication Date: 2012-06-13
西部超导材料科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 1) The critical current density is low and the superconductivity is poor; this method first mixes Mg powder and B powder, and then performs high temperature heat treatment
During the heat treatment, Mg diffuses to B, leaving holes in the Mg site, so that the generated MgB 2 The superconducting core is obviously porous and has a low density (usually only MgB 2 50% of theoretical density), resulting in MgB 2 The critical current density of the superconducting strip (J c ) is low and cannot meet the requirements of commercial applications
For example: usually at 20K, 3T, this strip J c Can only reach 500~600A / mm 2 ; Unable to satisfy MgB 2 Under the conditions of working temperature 20-26K and magnetic field 1.5-5T, the critical current density of superconducting strip is 1000A / mm 2 business application requirements
[0006] 2) Poor toughness, not easy to bend, and inconvenient to use: In order to improve the MgB in the superconducting core 2 The denseness of the coating layer used in the existing method is usually a high-strength metal or alloy in order to obtain a finer diameter wire, which is then rolled into a strip
The existence of the high-strength metal sheath cavity makes the overall toughness of the strip not enough, which brings difficulties in use and transportation
For example: for a superconducting strip with a thickness of 0.5mm and a width of 4mm produced by the existing method, the radius of curvature that does not damage the performance of the superconducting core is usually about 1 meter, and MgB is used to make magnets. 2 When making a superconducting tape, it usually needs to be wound on a cylindrical magnet with a radius not greater than 15cm. Therefore, it is difficult for the superconducting tape produced by the existing method to be used in commercial magnet applications.
[0007] 3) The production cost is high; firstly, in order to obtain a high critical current density, this MgB 2 Superconducting wire strips need to use high-purity amorphous boron powder, and this boron powder can only be produced in the United States at present, and the United States has restricted the export of this boron powder, so the production cost is very high
Second, the current MgB 2 The heat treatment temperature of the superconducting wire strip is usually 600-800°C, and the higher heat treatment temperature also increases the production cost

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] a. Making buffer layer: Coating 20nm thick Al on the Fe base band with a thickness of 0.2mm and a width of 10mm by chemical sol-gel method 2 o 3 as a buffer layer;

[0031] b. Coating precursor: Malic acid-doped Mg(BH 4 ) 2 Colloid, and adopt the method of pulling, this colloid is coated on the buffer layer that a step makes; Wherein malic acid and Mg(BH 4 ) 2 The mass ratio is 0.036:1;

[0032] c. Heat treatment: After step b is completed, put it into a heat treatment furnace, raise the temperature to 300°C under the protective atmosphere of argon atmosphere, keep it warm for 3 hours, and then cool it with the furnace, and then the "Fe baseband-Al 2 o 3 Buffer layer-Mg(B0.99 C 0.01 ) 2 Combination composed of superconducting layer;

[0033] d. Covering protective layer: Electron beam evaporation deposits a 2μm thick Ag layer on the combined body after step c heat treatment as a stabilizer and protective layer, and finally obtains C-doped MgB 2 superconducting...

Embodiment 2

[0036] a, make buffer layer: adopt the method for chemical solution to be on the stainless steel base belt that thickness is 0.1mm, width is 10mm, make one deck of 20nm thick MgO thin film as buffer layer;

[0037] b. Coating precursor: On the MgO buffer layer made in step a, evenly coat Mg(BH 4 ) 2 Precursors, among which, malic acid and Mg(BH 4 ) 2 The mass ratio is 0.108:1;

[0038] c. Heat treatment: After step b is completed, it is put into a heat treatment furnace. Under the protective atmosphere of argon atmosphere, the temperature is raised to 500°C, and it is kept for 1 hour and then cooled with the furnace, and the "stainless steel substrate-Al 2 o 3 Buffer layer-Mg(B 0.97 C 0.03 ) 2 Combination composed of superconducting layer;

[0039] d. Covering protective layer: Electron beam evaporation deposits a 5 μm thick Ag layer on the combined body after step c heat treatment as a stabilizer and protective layer, thus obtaining C-doped MgB 2 superconducting tape...

Embodiment 3

[0042] a. Making a buffer layer: using a chemical solution method to make a 20nm thick SiC thin film on a CuZr alloy substrate with a thickness of 0.3mm and a width of 10mm as a buffer layer;

[0043] b. Coating precursor: On the SiC buffer layer made in step a, evenly coat Mg(BH 4 ) 2 Precursors, among which, malic acid and Mg(BH 4 ) 2 The mass ratio is 0.18:1;

[0044] c. Heat treatment: After step b is completed, put it into a heat treatment furnace, raise the temperature to 400°C under the protective atmosphere of argon atmosphere, keep it warm for 2 hours, and then cool it with the furnace, and the "CuZr baseband-SiC buffer layer" is obtained. -Mg(B 0.95 C 0.05 ) 2 Combination composed of superconducting layer;

[0045] d. Covering protective layer: Electron beam evaporation deposits a 2 μm thick Ag layer on the combined body after step c heat treatment as a stabilizer and protective layer, thus obtaining C-doped MgB 2 superconducting tape;

[0046] The strip of ...

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Abstract

The invention relates to a preparation method of a carbon-doped magnesium diboride (MgB2) superconducting tape. The technical characteristic of the invention is characterized in that the method comprises the following steps that: a, a buffer layer film is deposed on a metal baseband; b, a malic acid-doped Mg(BH4)2 colloid is manufactured as well as the colloid is coated on the buffer layer film; c, the metal baseband that has been processed in the step b is placed under an protection atmosphere and is heated to a temperature of 300 to 500 DEG C, so that the malic acid- Mg(BH4)2 is deposed into a Mg(B1-XCX)2 superconductive alloy compound, wherein the X is equal to a value that is obtained by subtracting 0.l0 from 0.01; and d, metal having good electric conduction and heat conduction performances is covered on the surface of the Mg(B1-XCX)2 superconductive layer obtained by the step c so as to obtain a protection layer; that is, a practical carbon-doped MgB2 superconducting tape is obtained. Compared with a current method, the method provided in the invention enables the prepared MgB2 superconducting tape to have high critical current density, good heat stability and good flexibility; and moreover, manufacturing cost is low; and the method is suitable for industrialized production.

Description

technical field [0001] The invention relates to a method for manufacturing a superconducting strip, in particular to a method for preparing a carbon-doped magnesium diboride superconducting strip. Background technique [0002] High-performance superconducting materials are the basis for the development of large-scale superconducting power transmission, superconducting transformers, superconducting current limiters, superconducting magnets, superconducting energy storage and other applications. Magnesium diboride (MgB 2 ) superconducting tape is expected to replace traditional low-temperature superconducting materials and achieve large-scale commercial applications due to its high superconducting transition temperature, very high current carrying capacity, low raw material cost, and easy fabrication; especially in 15 Magnets with a temperature of ~26K and a magnetic field of less than 5T have huge market potential and are ideal for future medical nuclear magnetic resonance s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L39/24C01B35/04
Inventor 潘熙锋闫果冯勇刘向宏张丰收张平祥
Owner 西部超导材料科技股份有限公司
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