Preparation method of magnesium diboride superconducting wire

Abstract

The invention discloses a preparation method of a magnesium diboride superconducting wire. The preparation method comprises the following steps: dissolving B powder and Mg powder through an acid solution to obtain a B salt solution and an Mg salt solution; mixing the B salt solution and the Mg salt solution to obtain a mixed solution; atomizing the mixed solution through an ultrasonic atomization device; after argon and CxHy gas are added, mixed gas is blown into a heat treatment furnace, and precursor powder is obtained; carrying out phase heat treatment on the precursor powder, and then loading the precursor powder into an Nb / Cu composite tube to obtain a single-core rod; and the single-core rods are bundled and assembled into a Monel alloy tube to obtain a multi-core composite wire, and the multi-core composite wire is subjected to heat treatment to obtain the multi-core magnesium diboride superconducting wire. The MgB2-nCn powder is prepared by adopting a spray pyrolysis method, the proportion of element components is more uniform, and the C element is doped into the powder by adopting a gas phase in-situ method, so that the distribution of the C element in the powder is more uniform, and the C element forms a high-density pinning center, thereby improving the superconducting performance of the wire rod in a high field.

Description

Technical Field

[0001] The invention relates to the technical field of superconducting wires, and in particular to a method for preparing a magnesium diboride superconducting wire. Background Art

[0002] At present, practical NbTi and Nb3Sn superconducting wires have been industrialized and applied worldwide, and are mainly used in energy (thermonuclear fusion reactors), medical (medical magnetic resonance imaging), scientific research (accelerators, nuclear magnetic resonance) and other fields. However, since NbTi and Nb3Sn superconducting wires need to work in a liquid helium environment, the refrigeration energy consumption required for their engineering applications is relatively large, and helium has become an international strategic resource and is expensive. With the research and development of high-temperature superconducting materials, practical high-temperature superconducting materials that can work in liquid hydrogen / liquid nitrogen environments have received more attention. The transformation temperature of practical magnesium diboride high-temperature superconducting wires reaches 39 K, and the preparation technology of the wires is mature and low-cost, so it has great application value in medical magnetic resonance imaging, wind power motors, energy storage and other fields.

[0003] Practical magnesium diboride high-temperature superconducting wires are prepared using powder in tube technology, with metals such as Cu, Nb, and NCu30 alloy as stable matrices. The engineering application value of magnesium diboride wires in the liquid hydrogen temperature range is significant. In addition, some special engineering applications require magnesium diboride wires to serve in higher magnetic fields. However, due to the limitations of its own physical properties, magnesium diboride wires have a large attenuation in higher magnetic fields, which restricts the application potential of the wires. Summary of the invention

[0004] The embodiment of the present invention provides a method for preparing a magnesium diboride superconducting wire, which is used to solve the problem in the prior art that the magnesium diboride wire has a large attenuation in a higher magnetic field due to its own physical properties, thereby restricting the application potential of the wire.

[0005] On the one hand, an embodiment of the present invention provides a method for preparing a magnesium diboride superconducting wire, comprising: Dissolving B powder and Mg powder by an acid solution to obtain a B salt solution and a Mg salt solution; The B salt solution and the Mg salt solution are mixed and then deionized water is added to obtain a mixed solution; Atomizing the mixed solution through an ultrasonic atomization device to obtain an atomized mixed solution; Argon and C are introduced into the atomized mixed solution. x H y After the gas is generated, the mixed gas is blown into a heat treatment furnace to obtain a precursor powder; The precursor powder is subjected to phase heat treatment to obtain MgB 2 - nC n powder; The MgB 2 - n C n The powder is loaded into the Nb / Cu composite tube to obtain a single core rod; Assembling the single core rods into a monel alloy tube to obtain a multi-core composite wire; The multi-core composite wire is heat treated to obtain a multi-core magnesium diboride superconducting wire.

[0006] In a possible implementation, the dissolving of B powder and Mg powder by an acid solution to obtain a boron salt solution and a magnesium salt solution is performed by dissolving the B powder and Mg powder with a nitric acid solution to obtain B. 5+ Salt solution and Mg 2+ Saline solution.

[0007] In a possible implementation, the mixing of the B salt solution and the Mg salt solution and then adding deionized water to obtain a mixed solution comprises: The B 5+ The salt solution and the Mg 2+ The salt solutions were mixed in a molar ratio of Mg:B=1:2.

[0008] In a possible implementation, atomizing the mixed solution by an ultrasonic atomization device to obtain an atomized mixed solution is to uniformly pump the mixed solution into the ultrasonic atomization device by a peristaltic pump.

[0009] In a possible implementation, argon and C are introduced into the atomized mixed solution. x H y After the gas is produced, the mixed gas is blown into the heat treatment furnace to obtain the precursor powder including: Passing the argon gas into the pipeline of the ultrasonic atomization device; The C x H y The gas is introduced into the pipeline of the ultrasonic atomization device; The C x H y The gas and the atomized mixed solution are blown into the heat treatment furnace; The atomized mixed solution is decomposed by the heat treatment furnace to obtain the precursor powder containing only B, Mg and C elements.

[0010] In a possible implementation, the volume ratio of Nb and Cu in the Nb / Cu composite tube is fixed.

[0011] In a possible implementation, the MgB 2 - n Cn The powder is loaded into the Nb / Cu composite tube to obtain a single core rod comprising: The MgB 2 - n C n The powder is loaded into the Nb / Cu composite tube; By cold plastic processing, the MgB 2 - n C n The powder and the Nb / Cu composite tube are processed into the single core rod.

[0012] In a possible implementation, the bundling and assembling of the single core rods into a monel alloy tube to obtain a multi-core composite wire is performed by cold plastic processing.

[0013] The method for preparing a magnesium diboride superconducting wire in the present invention has the following advantages: (1) Preparation of MgB by spray pyrolysis 2 - n C n The powder prepared by this method has more uniform particle size, higher activity and more uniform element composition ratio.

[0014] (2) The C element is doped into the powder using a gas phase in-situ method, making the distribution of the C element in the powder more uniform. Therefore, during the solid-phase reaction of B powder and Mg powder, the C element will diffuse more effectively into the magnesium diboride lattice and form element substitution, forming a high-density pinning center, thereby improving the superconducting performance of the wire under high fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A flow chart of a method for preparing a magnesium diboride superconducting wire provided in an embodiment of the present invention; Figure 2 A magnesium diboride superconducting wire J according to a method for preparing a magnesium diboride superconducting wire provided in an embodiment of the present invention c -Schematic diagram of B (critical current density-magnetic field) curve. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Figure 1 A flowchart of a method for preparing a magnesium diboride superconducting wire provided in an embodiment of the present invention; an embodiment of the present invention provides a method for preparing a magnesium diboride superconducting wire, comprising: Dissolving B powder and Mg powder by an acid solution to obtain a B salt solution and a Mg salt solution; The B salt solution and the Mg salt solution are mixed and then deionized water is added to obtain a mixed solution; Atomizing the mixed solution through an ultrasonic atomization device to obtain an atomized mixed solution; Argon and C are introduced into the atomized mixed solution. x H y After the gas is generated, the mixed gas is blown into a heat treatment furnace to obtain a precursor powder; The precursor powder is subjected to phase heat treatment to obtain MgB 2 - n C n powder; The MgB 2 - n C n The powder is loaded into the Nb / Cu composite tube to obtain a single core rod; Assembling the single core rods into a monel alloy tube to obtain a multi-core composite wire; Heat treating the multi-core composite wire to obtain a multi-core magnesium diboride superconducting wire; The method of dissolving B powder and Mg powder by acid solution to obtain boron salt solution and magnesium salt solution is to dissolve B powder and Mg powder by nitric acid solution to obtain B 5+ Salt solution and Mg 2+ Saline solution; The step of mixing the B salt solution and the Mg salt solution and then adding deionized water to obtain a mixed solution comprises: The B 5+ The salt solution and the Mg 2+ The salt solution is mixed in a molar ratio of Mg:B=1:2; The mixed solution is atomized by an ultrasonic atomization device to obtain an atomized mixed solution, and the mixed solution is uniformly pumped into the ultrasonic atomization device by a peristaltic pump; Argon and C are introduced into the atomized mixed solution. x Hy After the gas is produced, the mixed gas is blown into the heat treatment furnace to obtain the precursor powder including: Passing the argon gas into the pipeline of the ultrasonic atomization device; The C x H y The gas is introduced into the pipeline of the ultrasonic atomization device; The C x H y The gas and the atomized mixed solution are blown into the heat treatment furnace; Decomposing the atomized mixed solution by the heat treatment furnace to obtain the precursor powder containing only B, Mg and C elements; The volume ratio of Nb and Cu in the Nb / Cu composite tube is fixed; The MgB 2 - n C n The powder is loaded into the Nb / Cu composite tube to obtain a single core rod comprising: The MgB 2 - n C n The powder is loaded into the Nb / Cu composite tube; By cold plastic processing, the MgB 2 - n C n Processing the powder and the Nb / Cu composite tube into the single core rod; The process of assembling the single core rods into a monel alloy tube to obtain a multi-core composite wire is performed by cold plastic processing.

[0019] For example, the purity of Mg powder and B powder is 99.9%, B5+ salt solution and Mg 2+ The concentration of the salt solution is 1 mol / L to 5 mol / L. The frequency of the ultrasonic atomization device is 100 Hz to 500 Hz. x H y The x of the gas is 1, 2, 3, 4, 5, 6..., y is 1, 2, 3, 4, 5, 6...; the argon gas and C x H y The volume percentages of the gases are 90% and 10% respectively; the temperature range of the high temperature decomposition of the droplets of the atomized mixed solution is 300°C to 500°C; the temperature of the precursor powder phase heat treatment is 600°C to 700°C; the MgB 2 - n C n The powder, wherein n is in the range of 0.1 to 0.5, and the heat treatment of the multi-core composite wire to obtain the multi-core magnesium diboride superconducting wire is completed at a temperature of 800° C. to 1000° C. for 5 h to 15 h.

[0020] In a possible embodiment, there is Example 1, wherein B powder and high-purity Mg powder are respectively dissolved in nitric acid solution, and the obtained B-containing 5+ and Mg 2+ The salt solution is mixed with the molar ratio of Mg:B=1:2, and then a certain volume of deionized water is placed in the solution to make the concentration of the mixed solution 1mol / L; the prepared mixed solution is passed into the ultrasonic atomization device through a peristaltic pump, and the ultrasonic frequency is set to 100Hz to atomize the solution into micron-sized droplets; high-purity argon gas is passed into the pipeline of the atomization device, and C 2 H 4 Gas is introduced into the pipeline, including argon and C 2 H 4 The volume percentages of gas are 90% and 10% respectively. 2 H 4 The gas enters the heat treatment furnace under the blowing of argon gas, and the nitrate droplets containing B and Mg elements undergo a decomposition reaction at 300°C to generate a precursor powder containing only B, Mg and C elements; the collected precursor powder is further subjected to phase heat treatment at 600°C to finally generate MgB 1.95 C 0.05 Powder; MgB 1.95 C 0.05 The powder is loaded into a Nb / Cu composite tube (the volume ratio of Nb and Cu is fixed), and it is cold-plastic processed into a single-core wire of a specific radial size, and then straightened and cut to obtain a single-core rod of a fixed shape and length. The single-core rods are further bundled and assembled into a monel alloy tube, and the bundled composite rods are cold-plastic processed to obtain a multi-core composite wire of a fixed size; the processed multi-core composite wire is kept at 800°C for 15 hours to finally obtain a multi-core magnesium diboride superconducting wire.

[0021] In a possible embodiment, there is Example 2, wherein B powder and high-purity Mg powder are respectively dissolved in nitric acid solution, and the obtained B-containing 5+ and Mg 2+ The salt solution was mixed with the molar ratio of Mg:B = 1:2, and then a certain volume of deionized water was placed in the solution to make the concentration of the mixed solution 2.5 mol / L; the prepared mixed solution was passed into the ultrasonic atomization device through a peristaltic pump, and the ultrasonic frequency was set to 250 Hz to atomize the solution into micron-sized droplets; high-purity argon gas was passed into the pipeline of the atomization device, and C 3 H 6 Gas is introduced into the pipeline, including argon and C 3 H 6 The volume percentages of gas are 90% and 10% respectively. 3 H 6The gas enters the heat treatment furnace under the blowing of argon gas, and the nitrate droplets containing B and Mg elements undergo a decomposition reaction at 400°C to generate a precursor powder containing only B, Mg and C elements; the collected precursor powder is further subjected to phase heat treatment at 600°C to finally generate MgB 1.9 C 0.1 Powder; MgB 1.9 C 0.1 The powder is loaded into a Nb / Cu composite tube (the volume ratio of Nb and Cu is fixed), which is cold-plastic processed into a single-core wire of a specific radial size, and then straightened and cut to obtain a single-core rod of a fixed shape and length. The single-core rods are further bundled and assembled into a monel alloy tube, and the bundled composite rods are cold-plastic processed to obtain a multi-core composite wire of a fixed size; the processed multi-core composite wire is kept at 900°C for 10 hours to finally obtain a multi-core magnesium diboride superconducting wire.

[0022] In a possible embodiment, there is Example 3, wherein B powder and high-purity Mg powder are respectively dissolved in nitric acid solution, and the obtained B-containing 5+ and Mg 2+ The salt solution is mixed with the molar ratio of Mg:B=1:2, and then a certain volume of deionized water is placed in the solution to make the concentration of the mixed solution 5mol / L; the prepared mixed solution is passed into the ultrasonic atomization device through a peristaltic pump, and the ultrasonic frequency is set to 500Hz to atomize the solution into micron-sized droplets; high-purity argon gas is passed into the pipeline of the atomization device, and C 4 H 8 Gas is introduced into the pipeline, including argon and C 4 H 8 The volume percentages of gas are 90% and 10% respectively. 4 H 8 The gas enters the heat treatment furnace under the blowing of argon gas, and the nitrate droplets containing B and Mg elements undergo a decomposition reaction at 500°C to generate a precursor powder containing only B, Mg and C elements; the collected precursor powder is further subjected to phase heat treatment at 600°C to finally generate MgB 1.85 C 0.15 Powder; MgB 1.85 C 0.15 The powder is loaded into a Nb / Cu composite tube (the volume ratio of Nb and Cu is fixed), which is cold-plastic processed into a single-core wire of a specific radial size, and then straightened and cut to obtain a single-core rod of a fixed shape and length. The single-core rods are further bundled and assembled into a monel alloy tube, and the bundled composite rods are cold-plastic processed to obtain a multi-core composite wire of a fixed size; the processed multi-core composite wire is kept at 1000℃ for 5h to finally obtain a multi-core magnesium diboride superconducting wire.

[0023] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0024] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a magnesium diboride superconducting wire, characterized in that: include: Dissolving B powder and Mg powder by an acid solution to obtain a B salt solution and a Mg salt solution; The B salt solution and the Mg salt solution are mixed and then deionized water is added to obtain a mixed solution; Atomizing the mixed solution through an ultrasonic atomization device to obtain an atomized mixed solution; Argon and C are introduced into the atomized mixed solution. x H y After the gas is generated, the mixed gas is blown into a heat treatment furnace to obtain a precursor powder; The precursor powder is subjected to phase heat treatment to obtain MgB2- n C n powder; The MgB2- n C n The powder is loaded into the Nb / Cu composite tube to obtain a single core rod; Assembling the single core rods into a monel alloy tube to obtain a multi-core composite wire; The multi-core composite wire is heat treated to obtain a multi-core magnesium diboride superconducting wire.

2. The method for preparing a magnesium diboride superconducting wire according to claim 1, characterized in that: The method of dissolving B powder and Mg powder by acid solution to obtain boron salt solution and magnesium salt solution is to dissolve B powder and Mg powder by nitric acid solution to obtain B 5+ Salt solution and Mg 2+ Saline solution.

3. The method for preparing a magnesium diboride superconducting wire according to claim 2, characterized in that: The step of mixing the B salt solution and the Mg salt solution and then adding deionized water to obtain a mixed solution comprises: The B 5+ The salt solution and the Mg 2+ The salt solutions were mixed in a molar ratio of Mg:B=1:

2.

4. The method for preparing a magnesium diboride superconducting wire according to claim 1, characterized in that: The mixed solution is atomized by an ultrasonic atomization device to obtain an atomized mixed solution, and the mixed solution is uniformly pumped into the ultrasonic atomization device by a peristaltic pump.

5. The method for preparing a magnesium diboride superconducting wire according to claim 4, characterized in that: Argon and C are introduced into the atomized mixed solution. x H y After the gas is produced, the mixed gas is blown into the heat treatment furnace to obtain the precursor powder including: Passing the argon gas into the pipeline of the ultrasonic atomization device; The C x H y The gas is introduced into the pipeline of the ultrasonic atomization device; The C x H y The gas and the atomized mixed solution are blown into the heat treatment furnace; The atomized mixed solution is decomposed by the heat treatment furnace to obtain the precursor powder containing only B, Mg and C elements.

6. The method for preparing a magnesium diboride superconducting wire according to claim 1, characterized in that: The volume ratio of Nb and Cu in the Nb / Cu composite tube is fixed.

7. The method for preparing a magnesium diboride superconducting wire according to claim 1, characterized in that: The MgB2- n C n The powder is loaded into the Nb / Cu composite tube to obtain a single core rod comprising: The MgB2- n C n The powder is loaded into the Nb / Cu composite tube; By cold plastic processing, the MgB2- n C n The powder and the Nb / Cu composite tube are processed into the single core rod.

8. The method for preparing a magnesium diboride superconducting wire according to claim 1, characterized in that: The single core rods are bundled and assembled into a monel alloy tube to obtain a multi-core composite wire by cold plastic processing.

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