CN103442546B - A kind of high-temperature superconductor magnetic shielding device and preparation method thereof - Google Patents

Abstract

The invention discloses a high temperature superconducting magnetic shielding device, which comprises a barrel body and a barrel cover, the barrel body includes a first cylinder closed at one end, the barrel cover includes a second cylinder closed at one end, the second The opening end of the drum is covered on the opening end of the first drum relative to the opening end of the first drum; the inner and outer surfaces of the first drum and the inner and outer surfaces of the second drum are all attached with silver film , a Bi-2212 superconducting film is attached to the silver film, and a metal thin film is attached to the Bi-2212 superconducting film. In addition, the invention also discloses a preparation method of the high-temperature superconducting magnetic shielding device. The magnetic shielding device of the present invention uses silver-plated high-temperature-resistant alloy composite materials instead of pure silver and silver alloys, the material cost is reduced by more than 95%, and the material strength is greatly increased; the surface metal film is used for protection, which reduces the impact on the use or storage environment. The impact of device performance; the use of inner and outer double-sided superconducting layer shielding increases the reliability of its shielding.

Description

A high temperature superconducting magnetic shielding device and its preparation method

technical field

The invention belongs to the technical field of superconducting shielding device preparation, and in particular relates to a high-temperature superconducting magnetic shielding device and a preparation method thereof.

Background technique

Since superconducting materials exhibit complete diamagnetism in the superconducting state, they are the first choice for the preparation of magnetic shielding devices. At present, superconducting shielding devices made of low-temperature Nb-based metal superconductors operating at 4.2K have been widely used. However, this device needs to operate in a Dewar with an extremely complex structure, and the refrigerant uses expensive liquid helium, which greatly increases the cost of device preparation and device operation.

After the high-temperature superconducting material that can work in the liquid nitrogen temperature zone (77K) is discovered, it is immediately made into a magnetic shielding device, but the high-temperature superconducting material is a ceramic material, and it is difficult to prepare a shielding device. If the ceramic material is directly used to prepare a shielding device , the required superconducting materials are more expensive, and the strength of this all-ceramic shielding device is low, which restricts its application.

The researchers found that a uniform melt-textured high-temperature superconducting Bi-2212 (Bi ₂ Sr ₂ CaCuO ₈ ) film can be prepared on the surface of large-area silver and silver alloys by commonly used dipping or spraying, thereby greatly reducing the magnetic field. Difficulty in preparing the shielding device. However, such a magnetic shielding device requires a large amount of silver, resulting in a high manufacturing cost of the shielding device. Therefore, it is of great significance to develop a low-cost superconducting magnetic shielding device for its large-scale application.

Contents of the invention

The technical problem to be solved by the present invention is to provide a low-cost high-temperature superconducting magnetic shielding device for the above-mentioned deficiencies in the prior art. The device adopts silver-plated high-temperature-resistant alloy composite material instead of pure silver and silver alloy, the material cost is reduced by more than 95%, and the material strength is greatly increased; the surface metal film is used for protection, which reduces the influence of the use or storage environment on the performance of the device ; The use of inner and outer double-sided superconducting layer shielding increases the reliability of its shielding. The high-temperature superconducting magnetic shielding device is immersed in liquid nitrogen, and when the external field is lower than 100-130 gauss, the magnetic field strength inside the shielding device is 0; after the shielding device is placed in water for 24 hours, there is no change in re-test performance.

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a high-temperature superconducting magnetic shielding device, which is characterized in that it includes a barrel body and a barrel cover, the barrel body includes a first cylinder with one end closed, and the barrel The cover includes a second cylinder with one end closed, the inner and outer surfaces of the first cylinder and the inner and outer surfaces of the second cylinder are all attached with a silver film, and a Bi-2212 superconducting film is attached to the silver film , the Bi-2212 superconducting film is attached with a metal thin film; the materials of the first drum and the second drum are high-temperature-resistant alloys; the high-temperature-resistant alloys refer to alloys resistant to high temperatures above 800°C.

In the above-mentioned high-temperature superconducting magnetic shielding device, the wall thickness of the first cylinder is 2mm to 3mm, the outer diameter is 100mm to 500mm, and the height is 200mm to 1000mm; the inner diameter of the second cylinder is smaller than that of the first cylinder. The outer diameter of the barrel is 5mm-15mm larger, the wall thickness of the second drum is 2mm-3mm, and the height is 20mm-50mm.

In the above-mentioned high-temperature superconducting magnetic shielding device, the high-temperature-resistant alloy is Ni5W alloy.

In the above-mentioned high-temperature superconducting magnetic shielding device, the thickness of the silver film is 20 μm-30 μm; the thickness of the Bi-2212 superconducting film is 20 μm-30 μm; the thickness of the metal thin film is 10 nm-20 nm.

In the above-mentioned high temperature superconducting magnetic shielding device, the metal thin film is a silver thin film or an aluminum thin film.

In addition, the present invention also provides a method for preparing the above-mentioned high-temperature superconducting magnetic shielding device, which is characterized in that the method includes the following steps:

Step 1, preparing the first drum and the second drum by welding high temperature resistant alloy plates;

Step 2, the inner and outer surfaces of the first drum described in step 1 and the inner and outer surfaces of the second drum described in step 1 are electroplated with silver film; the electroplating solution of the electroplating is a soluble silver salt solution; the The current density of electroplating is 0.2A/dm ² ~ 0.5A/dm ² , and the electroplating time is 60min ~ 200min;

Step 3, adopting the method of spraying or dipping, the inner and outer surfaces of the first drum after electroplating in step 2 and the inner and outer surfaces of the second drum after electroplating in step 2 are all coated with Bi-2212 powder Suspension: the Bi-2212 powder suspension is made by uniformly mixing organic solvent, Bi-2212 powder and binder according to the mass ratio of (50-100):(10-15):1;

Step 4, heat treatment after drying the first cylinder coated with Bi-2212 powder suspension in step 3 and the second cylinder coated with Bi-2212 powder suspension in step 3, to obtain Bi- 2212 superconducting film; the heat treatment process is: heating the first drum and the second drum to 10°C-15°C above the melting temperature of Bi-2212, and then cooling down at a rate of 1°C/h-10°C/h rate down to room temperature;

Step 5, evaporating a metal thin film on the Bi-2212 superconducting film described in step 4;

Step 6. Put the second cylinder after vapor-depositing the metal film in step 5 as the bung lid of the first cylinder after vapor-depositing the metal film in step 5, and cover the opening end of the first cylinder to obtain a closed high-temperature superconducting Magnetic shielding device.

In the above method, the mass concentration of the soluble silver salt solution in step 2 is 3% to 8%, and the soluble silver salt is silver nitrate or silver perchlorate.

In the above method, the content of the high-temperature superconducting phase in the Bi-2212 powder described in step three is not less than 95%.

In the above method, the organic solvent in step three is ethanol, methanol or acetone, and the binder is amino resin, phenolic resin or polyvinyl butyral.

In the above method, the evaporation time in step 5 is 20s-60s.

Compared with the prior art, the present invention has the following advantages:

1. The magnetic shielding device of the present invention uses silver-plated high-temperature-resistant alloy (preferably Ni5W alloy) composite material instead of pure silver and silver alloy, the material cost is reduced by more than 95%, and the yield strength of the material is increased from 60MPa of pure silver to 160MPa ;The surface metal film is used for protection, which reduces the influence of the use or storage environment on the performance of the device; the inner and outer double-sided superconducting layer is used for shielding, which increases the reliability of its shielding.

2. The magnetic shielding device of the present invention has simple preparation process, reasonable design, low manufacturing cost, and is suitable for large-scale production.

3. When the high-temperature superconducting magnetic shielding device of the present invention is immersed in liquid nitrogen, when the external field is lower than 100-130 gauss, the magnetic field strength inside the shielding device is 0; after the shielding device is placed in water for 24 hours, there is no change in re-test performance.

The technical solutions of the present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a schematic cross-sectional view of a barrel of a high-temperature superconducting magnetic shielding device of the present invention.

Fig. 2 is a schematic cross-sectional view of the barrel cover of the high-temperature superconducting magnetic shielding device of the present invention.

Explanation of reference signs:

1—the first drum; 2—the second drum; 3—silver film;

4—Bi-2212 superconducting film; 5—metal thin film.

detailed description

Example 1

As shown in Figures 1 and 2, the high temperature superconducting magnetic shielding device of this embodiment includes a barrel body and a barrel cover. Two cylinders 2, the inner and outer surfaces of the first cylinder 1 and the inner and outer surfaces of the second cylinder 2 are all attached with a silver film 3, and a Bi-2212 superconducting film 4 is attached on the silver film 3 , the Bi-2212 superconducting film 4 is attached with a metal thin film 5; the materials of the first drum 1 and the second drum 2 are high-temperature-resistant alloys; the high-temperature-resistant alloys are Ni5W alloys; The wall thickness of a drum 1 is 2 mm, the outer diameter is 100 mm, and the height is 200 mm; the inner diameter of the second drum 2 is 10 mm larger than the outer diameter of the first drum 1, and the wall thickness of the second drum 2 is 2 mm , a height of 30 mm; the thickness of the silver film 3 is 20 μm; the thickness of the Bi-2212 superconducting film 4 is 20 μm; the thickness of the metal film 5 is 10 nm; the metal film 5 is an aluminum film.

The preparation method of the high temperature superconducting magnetic shielding device of this embodiment is as follows:

Step 1. Prepare the first drum 1 and the second drum 2 by welding a Ni5W alloy plate with a thickness of 2 mm using argon arc welding or laser welding equipment;

Step 2, the inner and outer surfaces of the first drum 1 described in step 1 and the inner and outer surfaces of the second drum 2 described in step 1 are electroplated with silver film 3; the electroplating solution of the electroplating is a mass concentration of 5% silver nitrate solution; the current density of the electroplating is 0.3A/dm ² , and the electroplating time is 200min;

Step 3, adopting the method of spraying or dipping, the inner and outer surfaces of the first drum 1 after electroplating in step 2 and the inner and outer surfaces of the second drum 2 after electroplating in step 2 are all coated with Bi- 2212 powder suspension; the Bi-2212 powder suspension is made by uniformly mixing ethanol, Bi-2212 powder and polyvinyl butyral in a mass ratio of 50:10:1; the Bi-2212 powder The high temperature superconducting phase content is not less than 95%;

Step 4, heat treatment after drying the first cylinder 1 coated with Bi-2212 powder suspension in step 3 and the second cylinder 2 coated with Bi-2212 powder suspension in step 3, to obtain Bi-2212 superconducting film 4; the process of the heat treatment is: heating both the first cylinder 1 and the second cylinder 2 to 10°C (885°C) above the melting temperature of Bi-2212, and then heating at 1°C/h The cooling rate is reduced to room temperature;

Step 5, vapor-deposit metal thin film 5 on Bi-2212 superconducting film 4 described in step 4; the time of described vapor deposition is 20s;

Step 6, using the second cylinder 2 after vapor-depositing metal film 5 in step 5 as the bung cover of the first cylinder 1 after vapor-depositing metal film 5 in step 5 on the open end of first cylinder 1, to obtain Enclosed high temperature superconducting magnetic shielding device.

The high-temperature superconducting magnetic shielding device of this embodiment is immersed in liquid nitrogen, and when the external field is lower than 110 gauss, the magnetic field strength inside the shielding device is zero. After the shield was placed in water for 24 hours, there was no change in re-test performance.

Example 2

As shown in Figure 1 and Figure 2, the structure of the high temperature superconducting magnetic shielding device of this embodiment is the same as that of Embodiment 1, the difference being that: the outer diameter of the first cylinder 1 is 300mm, and the height is 300mm; The inner diameter of the second drum 2 is 15 mm larger than the outer diameter of the first drum 1, and the height of the second drum 2 is 20 mm; the thickness of the silver film 3 is 30 μm; the Bi-2212 superconducting film 4 The thickness of the metal film 5 is 30 μm; the thickness of the metal thin film 5 is 15 nm.

The preparation method of the high-temperature superconducting magnetic shielding device of this embodiment is the same as that of Example 1, where the difference is that: the electroplating solution of the electroplating is a silver perchlorate solution with a mass concentration of 3%; the current density of the electroplating The electroplating time is 0.5A/dm ² , and the electroplating time is 120min; the Bi-2212 powder suspension is prepared by uniformly mixing methanol, Bi-2212 powder and polyvinyl butyral in a mass ratio of 100:10:1; the The process of heat treatment is: heating both the first drum 1 and the second drum 2 to 15°C (890°C) above the melting temperature of Bi-2212, and then cooling down to room temperature at a cooling rate of 5°C/h; The time is 40s.

The high-temperature superconducting magnetic shielding device of this embodiment is immersed in liquid nitrogen, and when the external field is lower than 130 gauss, the magnetic field strength inside the shielding device is zero. After the shield was placed in water for 24 hours, there was no change in re-test performance.

Example 3

As shown in Figure 1 and Figure 2, the structure of the high temperature superconducting magnetic shielding device of this embodiment is the same as that of Embodiment 1, where the difference is that: the high temperature resistant alloy is Ni9W alloy; The wall thickness is 3 mm, the outer diameter is 500 mm, and the height is 1000 mm; the inner diameter of the second drum 2 is 5 mm larger than the outer diameter of the first drum 1, and the wall thickness of the second drum 2 is 3 mm, and the height is 50 mm; The thickness of the silver film 3 is 25 μm; the thickness of the Bi-2212 superconducting film 4 is 25 μm; the thickness of the metal thin film 5 is 20 nm; the metal thin film is a silver thin film.

The preparation method of the high-temperature superconducting magnetic shielding device of this embodiment is the same as that of Example 1, except that: the electroplating solution of the electroplating is a silver nitrate solution with a mass concentration of 8%; the current density of the electroplating is 0.2 A/dm ² , the electroplating time is 200min; the Bi-2212 powder suspension is prepared by mixing acetone, Bi-2212 powder and phenolic resin according to the mass ratio of 80:12:1; the heat treatment process is: Both the first drum 1 and the second drum 2 were heated to 12°C (887°C) above the melting temperature of Bi-2212, and then lowered to room temperature at a cooling rate of 10°C/h; the evaporation time was 60s.

The high-temperature superconducting magnetic shielding device of this embodiment is immersed in liquid nitrogen, and when the external field is lower than 100 gauss, the magnetic field strength inside the shielding device is zero. After the shield was placed in water for 24 hours, there was no change in re-test performance.

Example 4

As shown in Figure 1 and Figure 2, the structure of the high temperature superconducting magnetic shielding device of this embodiment is the same as that of Embodiment 1, the difference being that: the high temperature resistant alloy is Ni12W alloy; The wall thickness is 2.5 mm, and the wall thickness of the second drum 2 is 2.5 mm.

The preparation method of the high-temperature superconducting magnetic shielding device of this embodiment is the same as that of Example 1, where the difference is that: the electroplating solution of the electroplating is a silver perchlorate solution with a mass concentration of 5%; the current density of the electroplating 0.5A/dm ² , the electroplating time is 60min; the Bi-2212 powder suspension is composed of methanol, Bi-2212 powder and amino resin (such as urea-formaldehyde resin, melamine-formaldehyde resin, polyamide polyamine epichlorohydrin, etc.) Mixed evenly according to the mass ratio of 50:15:1.

The high-temperature superconducting magnetic shielding device of this embodiment is immersed in liquid nitrogen, and when the external field is lower than 130 gauss, the magnetic field strength inside the shielding device is zero. After the shield was placed in water for 24 hours, there was no change in re-test performance.

Example 5

As shown in FIG. 1 and FIG. 2 , the structure of the high-temperature superconducting magnetic shielding device of this embodiment is the same as that of Embodiment 2.

The preparation method of the high-temperature superconducting magnetic shielding device of this embodiment is the same as that of Example 2, and the difference is that: the electroplating solution of the electroplating is a silver nitrate solution with a mass concentration of 3%; the current density of the electroplating is 0.3 A/dm ² , the electroplating time is 150 min; the Bi-2212 powder suspension is prepared by uniformly mixing acetone, Bi-2212 powder and polyvinyl butyral at a mass ratio of 100:15:1.

The high-temperature superconducting magnetic shielding device of this embodiment is immersed in liquid nitrogen, and when the external field is lower than 130 gauss, the magnetic field strength inside the shielding device is zero. After the shield was placed in water for 24 hours, there was no change in re-test performance.

Example 6

As shown in FIGS. 1 and 2 , the structure of the high-temperature superconducting magnetic shielding device of this embodiment is the same as that of Embodiment 3.

The preparation method of the high-temperature superconducting magnetic shielding device of this embodiment is the same as that of embodiment 3, wherein the difference is that: the electroplating solution of the electroplating is a silver perchlorate solution with a mass concentration of 8%; the current density of the electroplating The electroplating time is 0.3A/dm ² , and the electroplating time is 100min; the Bi-2212 powder suspension is prepared by uniformly mixing ethanol, Bi-2212 powder and phenolic resin in a mass ratio of 100:12:1.

The high-temperature superconducting magnetic shielding device of this embodiment is immersed in liquid nitrogen, and when the external field is lower than 130 gauss, the magnetic field strength inside the shielding device is zero. After the shield was placed in water for 24 hours, there was no change in re-test performance.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the invention still belong to the technical solution of the present invention. within the scope of protection.

Claims (10)

1. A high temperature superconducting magnetic shielding device, characterized in that it comprises a staving and a bung, the staving comprises a first cylinder (1) with one end closed, and the bung comprises a second cylinder with one end closed (2), the opening end of the second drum (2) is covered on the opening end of the first drum (1) opposite to the opening end of the first drum (1); the first drum (1) The inner and outer surfaces of the first cylinder (1) and the inner and outer surfaces of the second cylinder (2) are attached with silver film (3), and the inner and outer surfaces of the first cylinder (1) are attached with the silver film (3) and the second cylinder A Bi-2212 superconducting film (4) is attached to the silver film (3) attached to the inner and outer surfaces of the barrel (2), and a metal thin film (5) is attached to the Bi-2212 superconducting film (4). ; The materials of the first drum (1) and the second drum (2) are high-temperature-resistant alloys; the high-temperature-resistant alloys refer to alloys resistant to high temperatures above 800°C. 2. A high-temperature superconducting magnetic shielding device according to claim 1, characterized in that, the wall thickness of the first drum (1) is 2mm-3mm, the outer diameter is 100mm-500mm, and the height is 200mm- 1000mm; the inner diameter of the second drum (2) is 5mm-15mm larger than the outer diameter of the first drum (1), the wall thickness of the second drum (2) is 2mm-3mm, and the height is 20mm-50mm. 3 . The high temperature superconducting magnetic shielding device according to claim 1 , wherein the high temperature resistant alloy is Ni5W alloy. 4 . 4. A high temperature superconducting magnetic shielding device according to claim 1, characterized in that, the thickness of the silver film (3) is 20 μm to 30 μm; the thickness of the Bi-2212 superconducting film (4) is 20 μm to 30 μm; the thickness of the metal thin film (5) is 10 nm to 20 nm. 5. A high temperature superconducting magnetic shielding device according to claim 1, characterized in that, the metal thin film (5) is a silver thin film or an aluminum thin film. 6. A method for preparing a high-temperature superconducting magnetic shielding device according to any one of claims 1 to 5, characterized in that the method comprises the following steps: Step 1, preparing the first drum (1) and the second drum (2) by welding high temperature resistant alloy plates; Step 2, the inner and outer surfaces of the first cylinder (1) in step one and the inner and outer surfaces of the second cylinder (2) in step one are electroplated with silver film (3); the electroplated The electroplating solution is a soluble silver salt solution; the current density of the electroplating is 0.2A/dm ² to 0.5A/dm ² , and the electroplating time is 60min to 200min; Step 3, adopting the method of spraying or dipping, the inner and outer surfaces of the first drum (1) after electroplating in step 2 and the inner and outer surfaces of the second drum (2) after electroplating in step 2 are both Coating Bi-2212 powder suspension; the Bi-2212 powder suspension is mixed uniformly by organic solvent, Bi-2212 powder and binder according to the mass ratio of (50～100):(10～15):1 production; Step 4, after drying the first cylinder (1) coated with Bi-2212 powder suspension in step 3 and the second cylinder (2) coated with Bi-2212 powder suspension in step 3 Carrying out heat treatment to obtain Bi-2212 superconducting film (4); the process of said heat treatment is: heating both the first cylinder (1) and the second cylinder (2) to 10°C to 15°C above the melting temperature of Bi-2212 °C, then drop to room temperature at a cooling rate of 1 °C/h to 10 °C/h; Step five, the Bi-2212 superconducting film (4) obtained on the inner and outer surfaces of the first cylinder (1) and the Bi-2212 superconducting film obtained on the inner and outer surfaces of the second cylinder (2) in step four Metal thin film (5) is vapor-deposited on the film (4); Step 6, use the second cylinder (2) after vapor-depositing the metal film (5) in step 5 as the bung cover of the first cylinder (1) after vapor-depositing the metal film (5) in step 5 on the first The open end of the drum (1) obtains a closed high temperature superconducting magnetic shielding device. 7. The method according to claim 6, wherein the mass concentration of the soluble silver salt solution in step 2 is 3% to 8%, and the soluble silver salt is silver nitrate or silver perchlorate. 8. The method according to claim 6, characterized in that the content of the high-temperature superconducting phase in the Bi-2212 powder in step three is not less than 95%. 9. The method according to claim 6, wherein the organic solvent in step 3 is ethanol, methanol or acetone, and the binding agent is amino resin, phenolic resin or polyvinyl butyral. 10. The method according to claim 6, characterized in that the evaporation time in step 5 is 20s-60s.