阅读说明：本技术 一种超导线材及其制备方法 (Superconducting wire and preparation method thereof ) 是由 张现平 马衍伟 王栋樑 姚超 董持衡 徐中堂 黄河 于 2020-05-11 设计创作，主要内容包括：本发明提供一种超导线材及其制备方法,所述超导线材包括单芯线材和包覆单芯线材的第一金属管,所述第一金属管管壁上设有一从上至下贯穿所述第一金属管管壁的开口。由于第一金属管的管壁上设有开口,从单芯线材中逸出的富裕元素则可以通过该开口逸出第一金属管,从而使得超导线材在热处理时不会因为富裕元素变为气态,增加第一金属管与单芯线材之间的蒸气压,进而不会在第一金属管与单芯线材表面间形成气泡,影响超导线材的性能。(The invention provides a superconducting wire and a preparation method thereof, wherein the superconducting wire comprises a single-core wire and a first metal tube for coating the single-core wire, and an opening penetrating through the wall of the first metal tube from top to bottom is formed in the wall of the first metal tube. Because the pipe wall of the first metal pipe is provided with the opening, the abundant elements escaping from the single-core wire can escape from the first metal pipe through the opening, so that the superconducting wire is prevented from becoming gaseous due to the abundant elements during heat treatment, the vapor pressure between the first metal pipe and the single-core wire is increased, and bubbles are prevented from being formed between the surfaces of the first metal pipe and the single-core wire to influence the performance of the superconducting wire.)

1. The superconducting wire is characterized by comprising a single-core wire and a first metal pipe for coating the single-core wire, wherein an opening which penetrates through the wall of the first metal pipe from top to bottom is formed in the wall of the first metal pipe.

2. The superconducting wire of claim 1, wherein the single core wire includes a second metal tube and a precursor powder disposed in the second metal tube, and the first metal tube has a mechanical strength greater than that of the second metal tube.

3. The superconducting wire of claim 2, wherein the first metal tube is made of one or more of copper, iron, nickel, Monel and stainless steel, and the second metal tube is made of silver and/or silver alloy.

4. A superconducting wire according to any one of claims 1 to 3, wherein the number of the single core wires is at least 1.

5. The superconducting wire of any one of claims 1-4, wherein the composition of the superconductor in the superconducting wire is (Ba/Sr)_1－xK_xFe₂As₂、SmFeAsO_1－xF_x、FeSe_1－xTe_xOr CaKFe₄As₄Wherein x is 0 to 1.

6. The method of producing a superconducting wire rod as claimed in any one of claims 1 to 5, characterized by comprising the steps of: the single-core wire is placed on a metal strip comprising a first end and a second end, the first end and the second end are close to each other to coat the single-core wire to form a composite wire, and a gap is formed between the first end and the second end after the coating is finished.

7. The method of manufacturing a superconducting wire according to claim 6, wherein the metal tape has a thickness of 0.001 to 0.5 mm.

8. The method of producing a superconducting wire according to claim 6 or 7, further comprising a step of drawing or rolling the clad composite wire.

9. The method of claim 8, wherein the composite wire is drawn or rolled at a pass reduction of 5-20%, and the diameter of the composite wire after drawing or rolling is 0.5-2.5 mm.

10. The method of manufacturing a superconducting wire according to claim 8 or 9, wherein the step of heat-treating the composite wire after drawing or rolling is further included: and carrying out heat treatment on the drawn or rolled composite wire rod in an inert atmosphere, and then annealing to room temperature.

11. The method of producing a superconducting wire according to any one of claims 6 to 10, wherein the single core wire is produced by:

preparing precursor powder: under an inert atmosphere, grinding, tubing and heat treatment are carried out on the raw materials to obtain precursor powder for preparing the superconducting wire;

single-core drawing: and filling the precursor powder into a metal tube, sealing two ends to obtain a tube-filling composite body, and drawing the tube-filling composite body to obtain the single-core wire.

12. The method of producing a superconducting wire according to claim 11, wherein a pass reduction rate of drawing the tube-packed composite is 5 to 20%.

13. The method for manufacturing a superconducting wire according to claim 11, wherein the precursor powder is manufactured by the steps of: ball-milling raw materials required by the superconducting wire in an inert atmosphere, filling the ball-milled powder into an Nb tube, sealing two ends of the Nb tube, and then carrying out heat treatment to obtain precursor powder.

14. The method for producing a superconducting wire according to claim 10, wherein the heat treatment temperature in the heat treatment step of the composite wire is 600-1000 ℃ and the heat treatment time is 0.1-50 hours; the heat treatment temperature in the preparation of the precursor powder is 600-1300 ℃, and the heat treatment time is 0.1-50 hours.

Technical Field

The invention relates to the technical field of superconducting material processing engineering, in particular to a superconducting wire and a preparation method thereof.

Background

Professor yokoxiuxiong of japan industrial university in tokyo in 2006 found an iron-based superconductor, which contains iron and has a superconducting phenomenon at low temperatures. Compared with the oxide high-temperature superconducting material, the iron-based superconductor has the advantages of simple crystal structure, large coherence length, small anisotropy, high critical magnetic field and low material cost, so the iron-based superconducting wire has great application advantages in the field of strong magnetic fields and is widely concerned by the international superconducting world. The critical transmission current density of the current iron-based superconductors exceeds 10⁵A/cm²[Realization of practical level current densities in S_r0.6K_0.4Fe₂As₂tapeconductors for high－field applications，Appl.Phys.Lett.104(2014)202601]It is marked that the performance of the iron-based superconducting wire has reached a practical level.

In the process of preparing the iron-based superconducting wire, factors influencing the performance of the iron-based superconducting wire are many, such as selection of metal coating materials, doping of chemical elements, cold working process of drawing, proper heat treatment temperature and the like in the process of preparing the wire by a powder tube-loading method. At present, when an iron-based superconducting wire is prepared, silver or silver alloy is generally adopted as a sheathing material in order to avoid the reaction between a superconducting core and the sheathing material; however, the density and uniformity of the superconducting core of the wire are poor due to the low mechanical strength of the silver or the silver alloy, so that the current-carrying performance of the wire is low; meanwhile, the lower mechanical strength of the sheath material also causes damage to the superconducting core in the wire processing or using process, and adverse influence is generated on the practicability of the iron-based compound superconducting wire. In the prior art, in order to improve the mechanical strength of an iron-based superconducting wire, a mode that a high-strength metal pipe is nested with a silver or silver alloy metal pipe filled with precursor powder and then is machined is often adopted, but because the iron-based superconductor has complex components and the chemical component proportion is difficult to control perfectly, excessive volatile elements such as K, F, Se are added in the preparation process of the precursor powder, after the precursor powder reacts to form a phase, rich elements can form gas to escape from the silver or silver alloy metal pipe at high temperature but cannot permeate the metal pipe with high mechanical strength on the outer layer, and if the superconducting wire is long, the gas formed by the rich elements cannot escape from the metal pipe on the outer layer easily, and vapor pressure can be formed between the silver or silver alloy metal pipe and the metal pipe on the outer layer, so that bubbles are left between two metal sheaths, and the performance of the superconducting wire is influenced.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a superconducting wire rod that overcomes the problem of the prior art that is unable to remove the abundant elements in the superconducting wire rod.

The invention also provides a preparation method of the superconducting wire.

Therefore, the invention provides a superconducting wire, which comprises a single-core wire and a first metal tube for coating the single-core wire, wherein an opening penetrating through the wall of the first metal tube from top to bottom is formed in the wall of the first metal tube. Preferably, the opening is a slit having a uniform gap width.

Furthermore, the single-core wire comprises a second metal tube and precursor powder arranged in the second metal tube, and the mechanical strength of the first metal tube is greater than that of the second metal tube. Specifically, the mechanical strength includes bending strength, tensile strength, and the like.

Furthermore, the first metal tube is made of one or more of copper, iron, nickel, Monel and stainless steel, and the second metal tube is made of silver and/or silver alloy.

Furthermore, the number of the single-core wires is at least 1.

Further, the composition of the superconductor in the superconducting wire is (Ba/Sr)_1－xK_xFe₂As₂、SmFeAsO_1－xF_x、FeSe_1－xTe_xOr CaKFe₄As₄Wherein x is 0 to 1.

The invention also provides a preparation method of the superconducting wire, which comprises the following steps: the single-core wire is placed on a metal strip comprising a first end and a second end, the first end and the second end are close to each other to coat the single-core wire to form a composite wire, and a gap is formed between the first end and the second end after the coating is finished.

Further, the metal strip has a thickness of 0.001 to 0.5 mm.

Further, the method also comprises the step of drawing or rolling the coated composite wire rod.

Furthermore, the pass processing rate of the drawing or rolling of the composite wire rod is 5-20%, and the diameter of the composite wire rod after drawing or rolling is 0.5-2.5 mm.

Further, the composite wire rod after being drawn or rolled further comprises the following heat treatment steps: and carrying out heat treatment on the drawn or rolled composite wire rod in an inert atmosphere, and then annealing to room temperature.

Further, the single-core wire is prepared by the following steps:

preparing precursor powder: under an inert atmosphere, grinding, tubing and heat treatment are carried out on the raw materials to obtain precursor powder for preparing the superconducting wire;

single-core drawing: and filling the precursor powder into a metal tube, sealing two ends to obtain a tube-filling composite body, and drawing the tube-filling composite body to obtain the single-core wire.

Furthermore, the pass processing rate of the drawing of the tubulation composite body is 5-20%.

Further, the preparation steps of the precursor powder are specifically as follows: ball-milling raw materials required by the superconducting wire in an inert atmosphere, filling the ball-milled powder into an Nb tube, sealing two ends of the Nb tube, and then carrying out heat treatment to obtain precursor powder.

Further, the heat treatment temperature in the heat treatment step of the composite wire is 600-; the heat treatment temperature in the preparation of the precursor powder is 600-1300 ℃, and the heat treatment time is 0.1-50 hours.

The technical scheme of the invention has the following advantages:

1. the superconducting wire comprises a single-core wire and a first metal tube for coating the single-core wire, wherein an opening is formed in the tube wall of the first metal tube, and rich elements escaping from the single-core wire can escape from the first metal tube through the opening due to the opening formed in the tube wall of the first metal tube, so that the superconducting wire is prevented from being changed into a gaseous state due to the rich elements during heat treatment, the vapor pressure between the first metal tube and the single-core wire is increased, bubbles are prevented from being formed between the surface of the first metal tube and the surface of the single-core wire, and the performance of the superconducting wire is not affected.

2. According to the superconducting wire rod provided by the invention, the second metal pipe of the single-core wire rod is made of silver and/or silver alloy, the first metal pipe with higher mechanical strength is coated outside the single-core wire rod, and the first metal pipe is made of one or more of copper, iron, nickel, Monel and stainless steel, so that the problems of low mechanical strength of the metal pipe of the single-core wire rod, poor density and uniformity of the superconducting core of the wire rod, low current-carrying performance of the wire rod and the like are effectively solved; meanwhile, the first metal pipe has high mechanical strength, so that the superconducting core can be prevented from being damaged in the wire processing or using process, and the practical potential of the superconducting wire is obviously improved.

3. According to the preparation method of the superconducting wire rod, the metal belt is coated on the outer layer of the single-core wire rod in a coating mode to form the outer layer metal pipe, gaps are formed in the formed outer layer metal pipe, formed micro-gaps serve as passages for permeation of rich elements to escape from the superconducting wire rod, and the phenomenon of bubbles between the two layers of metal pipes of the wire rod is avoided.

4. The preparation method of the iron-based superconducting wire rod provided by the invention has the advantages that the thickness of the metal belt for coating is smaller, and the preparation of the superconducting wire rod with high process current density is more facilitated.

5. According to the preparation method of the iron-based superconducting wire, provided by the invention, when a long wire is prepared, the length of the wire is not limited, and a kilometer-grade metal belt can be used for continuous coating; the requirement on the thickness of the cladding belt is low, the influence on the engineering current density of the reinforced superconducting wire is small, and the method is more suitable for the processing preparation and practical application requirements of the high-mechanical-strength superconducting long wire.

6. According to the preparation method of the iron-based superconducting wire, the component elements can fully react to generate a stable superconducting phase by optimizing and selecting the heat treatment temperature and time in the heat treatment process in the preparation of the precursor powder.

7. The preparation method of the iron-based superconducting wire meets different requirements by adopting different metal belts, reduces the cost to different degrees and improves the machining performance of the iron-based superconducting wire.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a sectional view of a superconducting wire rod of one embodiment mode in embodiment 1;

FIG. 2 is a partial side view of a superconducting wire rod in example 1;

FIG. 3 is a sectional view of a superconducting wire according to another embodiment of example 1;

FIG. 4 is a drawing showing the preparation of 7-core Ba in example 2 of the present invention_0.6K_0.4Fe₂As₂A schematic view of a superconducting wire;

FIG. 5 is a 7-core Ba prepared in example 2 of the present invention_0.6K_0.4Fe₂As₂An enlarged cross-sectional view of the superconducting wire;

FIG. 6 is a view showing preparation of 1-core Ba in example 3 of the present invention_0.6K_0.4Fe₂As₂A schematic view of a superconducting wire;

FIG. 7 is a 1-core Ba prepared in example 3 of the present invention_0.6K_0.4Fe₂As₂An enlarged cross-sectional view of the superconducting wire;

FIG. 8 is a 1-core Ba prepared in comparative example 1 of the present invention_0.6K_0.4Fe₂As₂An enlarged cross-sectional view of the superconducting wire.

Wherein, the reference numbers:

1-a first metal tube; 2-opening; 3-a second metal tube; 4-precursor powder.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.