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CN-115692012-B - Preparation method of second-generation high-temperature superconducting tape closed coil and closed magnet

CN115692012BCN 115692012 BCN115692012 BCN 115692012BCN-115692012-B

Abstract

The invention discloses a preparation method of a closed coil of a second-generation high-temperature superconducting tape and a closed magnet, and belongs to the technical field of high-temperature superconducting application. The preparation method comprises the steps of winding a superconducting strip into a superconducting coil, reserving two ends of the superconducting strip as two joints to be connected, removing a protective layer of the joints to expose the superconducting layer, coating precursor liquid on the superconducting layer, performing heat treatment on the superconducting coil at a first set temperature to enable the coated precursor liquid to be changed into gel, preparing concave-convex alternate channels on the gel, overlapping the two joints to be connected through the channels, performing heat treatment on the superconducting coil at a second set temperature to enable the gel to be changed into tetragonal phase crystals, annealing the superconducting coil in an oxygen atmosphere to enable the tetragonal phase crystals to be changed into orthorhombic phase crystals, and bridging the two joints to be connected with the orthorhombic phase crystals to obtain the closed coil. The closed magnet obtained based on the preparation method provided by the invention can realize non-attenuation closed-loop operation.

Inventors

  • DING FAZHU
  • GU HONGWEI
  • HUANG DAXING
  • DONG HAO
  • WANG JIE

Assignees

  • 中国科学院电工研究所

Dates

Publication Date
20260512
Application Date
20221109

Claims (8)

  1. 1. The preparation method of the second-generation high-temperature superconducting tape closed coil is characterized by comprising the following steps of: winding a second-generation high-temperature superconducting tape into a superconducting coil, and reserving two ends of the superconducting coil as two joints to be connected, wherein the second-generation high-temperature superconducting tape sequentially comprises a metal base tape layer, a buffer layer, a superconducting layer and a protective layer from bottom to top, and the superconducting layer comprises the following components in percentage by weight Wherein RE is a rare earth element, x=0 to 1; Removing the protective layer of the joint to be connected to expose the superconducting layer of the joint to be connected; Coating precursor liquid on the superconducting layer of the joint to be connected, wherein the precursor liquid is a solution containing components of the superconducting layer, the precursor liquid is fluorine-free acetate solution containing rare earth elements, barium elements and copper elements, and the rare earth elements are yttrium elements or gadolinium elements; performing heat treatment on the superconducting coil at a first set temperature to enable precursor liquid coated on the joint to be connected to be gel; Preparing concave-convex alternate channels on the gel; Overlapping the two joints to be connected through the channels, and performing heat treatment on the superconducting coil at a second set temperature to change gel on the joints to be connected into tetragonal phase crystals, wherein the second set temperature is higher than the first set temperature; annealing the superconducting coil in an oxygen atmosphere to change the tetragonal phase crystal into an orthorhombic phase crystal; and bridging the two joints to be connected with the orthorhombic crystals to obtain the closed coil.
  2. 2. The method for manufacturing a closed coil of a second generation high temperature superconducting tape according to claim 1, wherein the protective layer of the joint to be connected is removed by etching.
  3. 3. The method for manufacturing a closed coil of a second-generation high-temperature superconducting tape according to claim 1, wherein a precursor solution is coated on the superconducting layer of the joint to be connected by means of drop coating or dip coating.
  4. 4. The method for manufacturing a closed coil of a second-generation high-temperature superconducting tape according to claim 1, wherein the first set temperature is 300-650 ℃, and the heating time of the superconducting coil by heat treatment at the first set temperature is 60-180 min.
  5. 5. The method for manufacturing a closed coil of a second-generation high-temperature superconducting tape according to claim 1, wherein the second set temperature is 800-900 ℃, and the heat preservation time of the superconducting coil by the second set temperature is 60-300 min.
  6. 6. The method for manufacturing a closed coil of a second-generation high-temperature superconducting tape according to claim 1, wherein the width of the channel is 5-10 μm.
  7. 7. The method for manufacturing a closed coil of a second generation high temperature superconducting tape according to claim 1, wherein the oxygen atmosphere is oxygen with a purity of 99.9%, and the oxygen pressure is 15-100Mpa.
  8. 8. A second generation high temperature superconducting tape closing magnet, comprising: dewar, current lead, voltage lead and closed coil prepared by the preparation method of the second generation high temperature superconductive tape closed coil according to any of claims 1 to 7; The closed coil is positioned in the dewar, the current lead and the voltage lead are connected with the closed coil, and the current lead and the voltage lead are led out from the dewar.

Description

Preparation method of second-generation high-temperature superconducting tape closed coil and closed magnet Technical Field The invention relates to the technical field of high-temperature superconducting application, in particular to a preparation method of a closed coil of a second-generation high-temperature superconducting tape and a closed magnet. Background The nuclear magnetic resonance imaging (Magnetic Resonance Imaging, abbreviated as MRI) technology utilizes the principle of nuclear magnetic resonance, and detects the emitted electromagnetic waves through an externally applied gradient magnetic field according to different attenuations of the released energy in different structural environments inside a substance, so that the positions and types of nuclei constituting the object can be known, and accordingly, the structural image inside the object can be drawn. It does not require electron beam or X-ray, nor injection of contrast agent, nor finds the harm of strong magnetic field to human body, and is thus considered as a safe and efficient biomedical detection technology. The definition of the MRI has important relations with the magnetic field intensity, the magnetic field uniformity and the magnetic field stability, and the higher the magnetic field intensity, the better the magnetic field uniformity and the better the magnetic field stability, the higher the definition of the MRI. Currently, most MRI devices in the world use NbTi superconducting alloys. NbTi superconducting alloy belongs to low-temperature superconducting materials (Low Temperature Superconductor, LTS for short), and is found by J.K.Hulm et al in Western laboratory of America, the superconducting critical temperature Tc is 9.7K, and the upper critical magnetic field at 4.2K is about 11T. The NbTi wire is generally prepared into alloy by a high-temperature smelting method, then is drawn into a multi-core wire (hundreds of cores to tens of thousands of cores) for multiple times, and finally is subjected to heat treatment to form the (alpha+beta) dual-phase alloy. The NbTi superconducting alloy has good superconducting performance, good plasticity and strength under a medium-low magnetic field, and a processing technology is simpler, so that the NbTi superconducting alloy becomes the superconducting material which is most widely applied at present. But NbTi can only be used in a liquid helium environment, is very expensive to use, and its upper critical field also limits the magnetic field strength of the developed magnet. The second-generation high-temperature superconducting material represented by REBa 2Cu3O7-x (abbreviated as REBCO) has great application potential in superconducting magnets and the like due to the advantages of small anisotropism, high irreversible field and strong current carrying capacity. However, the biggest problem of the second generation high temperature superconducting tape in nuclear magnetic imaging is that the second generation high temperature superconducting tape cannot be operated in a closed loop. The REBCO superconducting layer in the second-generation high-temperature superconducting tape is ceramic oxide and very brittle, and the REBCO superconducting material has weak connection, so that the included angle between grains is larger than 7 degrees and the conduction cannot be realized. Both of these result in very difficult connections between REBCO superconducting layer faces. Therefore, no patent has been reported for closed magnets based on REBCO superconducting tapes. Disclosure of Invention The invention aims to provide a preparation method of a second-generation high-temperature superconducting tape closed coil and a closed magnet so as to realize non-attenuation closed-loop operation of the closed magnet. In order to achieve the above object, the present invention provides the following solutions: a preparation method of a second-generation high-temperature superconducting tape closed coil comprises the following steps: winding a second-generation high-temperature superconducting tape into a superconducting coil, and reserving two ends of the superconducting coil as two joints to be connected; Removing the protective layer of the joint to be connected to expose the superconducting layer of the joint to be connected; Coating precursor liquid on the superconducting layer of the joint to be connected, wherein the precursor liquid is a solution containing components of the superconducting layer; performing heat treatment on the superconducting coil at a first set temperature to enable precursor liquid coated on the joint to be connected to be gel; Preparing concave-convex alternate channels on the gel; Overlapping the two joints to be connected through the channels, and performing heat treatment on the superconducting coil at a second set temperature to change gel on the joints to be connected into tetragonal phase crystals, wherein the second set temperature is higher than the first set