Method for growing single-domain gadolinium-barium-copper-oxygen superconducting block through infiltration welding

Abstract

The invention discloses a method for growing a single-domain gadolinium-barium-copper-oxide superconducting block by infiltration welding, which adopts a top seed crystal infiltration growth method, and can effectively improve the successful preparation rate of the single-domain gadolinium-barium-copper-oxide superconducting block by splicing a plurality of samples which fail in growth and then performing infiltration growth. In the whole process, the BaCuO2 powder is prepared only through solid-state reaction, the experimental link is simplified, the preparation efficiency is improved, the preparation cost is reduced, and the purpose of preparing the large-size and high-performance single-domain gadolinium barium copper oxide superconducting block is achieved. The method can be used for preparing the gadolinium-barium-copper-oxygen superconducting block material through welding growth of samples failed in growth, and can also be used for preparing other series of high-temperature superconducting block materials such as Yb, Y, Sm, Nd, Eu and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of high-temperature copper oxide superconducting materials, and specifically relates to a method for preparing low-cost, complex-shaped single-domain gadolinium barium copper oxide superconducting bulk materials through melt infiltration welding growth. Background Art

[0002] Since the discovery of high-temperature superconducting bulk materials (HTS) 30 years ago, it has been one of the hot topics and key contents of research. In order to enable the further industrial production and application of gadolinium barium copper oxide (GdBCO) superconducting bulk materials, it is necessary not only to reduce the preparation cost and improve the production efficiency of the products, but also to maximize the superconducting properties of the samples, such as magnetic levitation force, trapped magnetic flux density, critical current density, etc. However, it can be seen from the existing literature reports that the growth of high-temperature superconducting bulk materials is heavily dependent on the control of supercooling and seed nucleation, and the slow cooling time always needs to be extended during the preparation process. Therefore, the preparation of samples is a slow process, and it takes more than 4 days to prepare single-domain REBCO superconducting bulk materials. At the same time, the defects such as microcracks and pores generated in the samples, and the grain boundary connectivity in the samples are significantly reduced, so that the superconducting properties of the samples tend to decrease with the increase of sample size. This is because the essence of the trapped magnetic field is determined by the range and size of the current loop that can be established, which means that the preparation of high-quality, large-size, and complex-shaped single-domain REBCO superconducting bulk materials is more difficult, which seriously hinders the practical application of such materials.

[0003] Therefore, a method can be found to combine many smaller single-domain REBCO superconducting blocks into a large-sized, arbitrary-shaped superconducting block, which will also solve the key problems of large-sized, complex-geometry high-temperature superconducting blocks required in the fields of nuclear magnetic resonance, energy storage flywheels, and superconducting motors. However, due to the unique high brittleness and high hardness of REBCO superconducting blocks, it is difficult to effectively control their connection process, which almost eliminates the possibility of preparing high-temperature superconducting blocks with complex geometries.

[0004] In addition, the existing method for preparing single-domain gadolinium barium copper oxide superconducting bulk materials has a low yield rate. Reusing samples that have failed to grow and improving resource utilization are also difficult problems that need to be urgently solved in the current field. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for growing a single-domain gadolinium barium copper oxide superconducting bulk material by infiltration welding.

[0006] The technical solution adopted to solve the above technical problems consists of the following steps:

[0007] S1, prepare BaCuO2 powder

[0008] BaCO3 and CuO powder are mixed in a molar ratio of 1:1 to prepare BaCuO2 powder by a solid state reaction method;

[0009] S2, Pretreatment of multi-domain samples

[0010] Cutting a plurality of multi-domain gadolinium barium copper oxide superconducting blocks, and pre-processing such as rough grinding, fine grinding, and polishing into semi-cylinders, wherein the semi-cylinders are called solid phase blocks;

[0011] S3, Pressed high temperature solder billet

[0012] Gd2O3 and BaCuO2 powders are mixed in a molar ratio of 1:1.2 to prepare a mixed powder; the mixed powder is added into a ball mill and mixed evenly, and the mixed powder is placed in a mold and pressed into a high-temperature solder blank;

[0013] S4, pressed ring-shaped block

[0014] Gd2O3 and BaCuO2 powders are mixed in a molar ratio of 1:1.2 to prepare a mixed powder; the mixed powder is added to a ball mill and mixed evenly, and the mixed powder is placed in a ring mold and pressed into a ring-shaped block having an inner diameter equal to that of the solid phase block;

[0015] S5, preparation of liquid source precursor powder

[0016] Y2O3, CuO powder and BaCuO2 powder are mixed uniformly in a molar ratio of 1:(4+6x):(2+4x) as liquid source precursor powder, wherein 1 is between 1.0 and 2.0;

[0017] S6, suppressed liquid source precursor block

[0018] Pressing the liquid source precursor powder into a cylinder having a diameter greater than the outer diameter of the annular compact to serve as a liquid source precursor block;

[0019] S7, pressed support block

[0020] The Yb2O3 powder is pressed into a cylinder with the same diameter as the liquid source precursor block as a support block;

[0021] S8, blank assembly

[0022] The high temperature solder in S3 is cut and placed between the two solid phase blocks in S2 as the high temperature solder, the annular blank in S4 is placed around the two solid phase blocks as the solid phase precursor block, and the MgO single crystal, the support block in S7, the liquid phase source precursor block in S6, the solid phase precursor block, and the NdBariumCuO seed crystal block are placed in order from bottom to top on the upper surface of the Al2O3 gasket to assemble into a blank;

[0023] S9, single domain gadolinium barium copper oxide bulk material grown by infiltration welding

[0024] The assembled green body is placed in a tubular furnace, heated to 900°C at a heating rate of 100-150°C per hour, kept at this temperature for 20 hours, then heated to 1050-1065°C at a heating rate of 40-80°C per hour, kept at this temperature for 1-2.5 hours, then cooled to 1030-1040°C at a cooling rate of 50-80°C per hour, then slowly cooled to 1010-1040°C at a cooling rate of 0.1-1°C per hour, and naturally cooled to room temperature with the furnace to obtain a gadolinium barium copper oxide block material;

[0025] S10, oxygen treatment

[0026] The gadolinium barium copper oxide block is placed in a quartz tube furnace and slowly cooled for 200 hours in a circulating oxygen atmosphere at a temperature range of 440 to 350° C. to obtain a gadolinium barium copper oxide superconducting block.

[0027] Furthermore, in S2, a plurality of multi-domain Gd-Bar-Cu-O blocks are cut and classified according to the growth failure conditions and cut into two halves or three halves.

[0028] Furthermore, in S3, after the mixed powder is evenly mixed, it is placed in a cylindrical mold and pressed into a high-temperature welding block having a diameter larger than that of the solid phase block.

[0029] Further, in S4, when the annular block is pressed, the inner diameter is equal to the solid phase block, and the difference between the outer diameter and the inner diameter is between 10-30 mm.

[0030] Further, in S5, x is preferably 1.5.

[0031] Further, in S9, the assembled blank is placed in a tubular furnace, heated to 900°C at a heating rate of 120°C per hour, kept at this temperature for 20 hours, then heated to 1056°C at a heating rate of 60°C per hour, kept at this temperature for 2 hours, then cooled to 1035°C at a cooling rate of 60°C per hour, slowly cooled to 1015°C at a cooling rate of 0.4°C per hour, and naturally cooled to room temperature with the furnace to obtain a single-domain gadolinium barium copper oxide block.

[0032] Compared with the prior art, the technical effects achieved by this technical solution are:

[0033] 1. Samples that failed to grow can be reused to improve the success rate of sample preparation;

[0034] 2. Several superconducting blocks can be welded to form large-sized superconducting blocks and superconducting blocks of various shapes without affecting their superconducting properties;

[0035] 3. The present invention only requires solid-state reaction to prepare BaCuO2 powder during the entire process, which simplifies the experimental steps, improves the preparation efficiency, and reduces the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a process flow chart of the growth of single-domain gadolinium barium copper oxide superconducting bulk material by infiltration welding;

[0037] Figure 2 It is a schematic diagram of the assembly of single-domain gadolinium barium copper oxide superconducting bulk material grown by infiltration welding;

[0038] Figure 3 This is a physical picture of the assembly of single-domain gadolinium barium copper oxide superconducting bulk material grown by infiltration welding;

[0039] Figure 4 This is the surface morphology of the single-domain gadolinium barium copper oxide superconducting bulk material prepared by infiltration welding growth;

[0040] Figure 5 It is the superconducting critical transition temperature curve of single-domain Gd-Ba-Cu-O superconducting bulk material grown by infiltration welding;

[0041] Figure 6 This is the XRD pattern of the surface of the single-domain Gd-Ba-Cu-O superconducting bulk material prepared by infiltration welding growth;

[0042] Figure 7 This is the SEM morphology of the weld of the single-domain Gd-Ba-Cu-O superconducting bulk material prepared by infiltration welding growth;

[0043] In the figure, 1. NdBarCuO seed crystal block; 2. High temperature solder blank block; 3. Solid phase precursor block; 4. Ring blank block; 5. Liquid phase source precursor block; 6. Support block; 7. MgO single crystal crystal; 8. Al2O3 gasket. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the present invention is not limited to these embodiments.

[0045] Embodiment 1

[0046] See also Figure 1-Figure 4

[0047] 1. Preparation of BaCuO2 powder

[0048] One mole of BaCO3 is mixed with one mole of CuO powder and BaCuO2 powder is prepared by a solid state reaction method.

[0049] 2. Pretreatment of multi-domain samples

[0050] A number of multi-domain gadolinium barium copper oxide superconducting blocks are cut, roughly ground, finely ground, polished, and pre-processed into semi-cylinders.

[0051] 3. Pressing high temperature solder blanks

[0052] 1 mol of analytically pure Gd2O3 and 1.2 mol of BaCuO2 powder are mixed to prepare a mixed powder; the mixed powder is added into a ball mill and mixed evenly, and the mixed powder is placed in a mold and pressed into a high-temperature solder blank.

[0053] 4. Pressing ring blocks

[0054] 1 mol of analytically pure Gd2O3 and 1.2 mol of BaCuO2 powder are mixed to prepare a mixed powder; the mixed powder is added to a ball mill and mixed evenly, and is placed in a ring mold and pressed into an inner diameter equal to that of a solid phase block.

[0055] 5. Prepare liquid source precursor powder

[0056] Mix 1 mol of analytically pure Y2O3, 10 mol of CuO powder and 6 mol of BaCuO2 powder to form the liquid source precursor powder;

[0057] 6. Pressing the liquid source precursor block

[0058] The liquid source precursor powder is pressed into a cylinder having a diameter larger than the outer diameter of the annular compact to serve as a liquid source precursor block.

[0059] 7. Suppression support

[0060] The Yb2O3 powder is pressed into a cylinder with the same diameter as the liquid source precursor block as a support block.

[0061] 8. Blank assembly

[0062] The high-temperature solder is cut and placed between two multi-domain solid phase blocks as high-temperature solder. The annular green block is put on the periphery of the multi-domain solid phase as a solid phase block. MgO single crystal crystal, support block, liquid source precursor block, solid phase precursor block, and NdBariumCuO seed crystal block are placed in sequence from bottom to top on the upper surface of the Al2O3 gasket to assemble into a green body.

[0063] 9. Infiltration welding growth of single domain gadolinium barium copper oxide bulk material

[0064] The assembled blank was placed in a tubular furnace, heated to 900°C at a heating rate of 100°C per hour, kept warm for 20 hours, then heated to 1050°C at a heating rate of 40°C per hour, kept warm for 1 hour, then cooled to 1040°C at a cooling rate of 50°C per hour, then slowly cooled to 1040°C at a cooling rate of 0.1°C per hour, and naturally cooled to room temperature with the furnace to obtain a gadolinium barium copper oxide block.

[0065] 10. Oxygen treatment

[0066] The gadolinium barium copper oxide block is placed in a quartz tube furnace and slowly cooled for 200 hours in a circulating oxygen atmosphere at a temperature of 440° C. to obtain a gadolinium barium copper oxide superconducting block.

[0067] Implementation 2

[0068] See also Figure 1-Figure 4

[0069] 1. Preparation of BaCuO2 powder

[0070] One mole of BaCO3 is mixed with one mole of CuO powder and BaCuO2 powder is prepared by a solid state reaction method.

[0071] 2. Pretreatment of multi-domain samples

[0072] A number of multi-domain gadolinium barium copper oxide superconducting blocks are cut, roughly ground, finely ground, polished, and pre-processed into semi-cylinders.

[0073] 3. Pressing high temperature solder blanks

[0074] 1 mol of analytically pure Gd2O3 and 1.2 mol of BaCuO2 powder are mixed to prepare a mixed powder; the mixed powder is added into a ball mill and mixed evenly, and the mixed powder is placed in a mold and pressed into a high-temperature solder blank.

[0075] 4. Pressing ring blocks

[0076] 1 mol of analytically pure Gd2O3 and 1.2 mol of BaCuO2 powder are mixed to prepare a mixed powder; the mixed powder is added to a ball mill and mixed evenly, and is placed in a ring mold and pressed into an inner diameter equal to that of a solid phase block.

[0077] 5. Prepare liquid source precursor powder

[0078] Mix 1 mol of analytically pure Y2O3, 16 mol of CuO powder and 10 mol of BaCuO2 powder to form the liquid source precursor powder;

[0079] 6. Pressing the liquid source precursor block

[0080] The liquid source precursor powder is pressed into a cylinder having a diameter larger than the outer diameter of the annular compact to serve as a liquid source precursor block.

[0081] 7. Suppression support

[0082] The Yb2O3 powder is pressed into a cylinder with the same diameter as the liquid source precursor block as a support block.

[0083] 8. Blank assembly

[0084] The high-temperature solder is cut and placed between two multi-domain solid phase blocks as high-temperature solder. The annular green block is put on the periphery of the multi-domain solid phase as a solid phase block. MgO single crystal crystal, support block, liquid source precursor block, solid phase precursor block, and NdBariumCuO seed crystal block are placed in sequence from bottom to top on the upper surface of the Al2O3 gasket to assemble into a green body.

[0085] 9. Infiltration welding growth of single domain gadolinium barium copper oxide bulk material

[0086] The assembled blank was placed in a tubular furnace, heated to 900°C at a heating rate of 150°C per hour, kept warm for 20 hours, then heated to 1065°C at a heating rate of 80°C per hour, kept warm for 1 hour, then cooled to 1010°C at a cooling rate of 80°C per hour, then slowly cooled to 1010°C at a cooling rate of 1°C per hour, and naturally cooled to room temperature with the furnace to obtain a gadolinium barium copper oxide block.

[0087] 10. Oxygen treatment

[0088] The gadolinium barium copper oxide block material is placed in a quartz tube furnace and slowly cooled in a circulating oxygen atmosphere at a temperature zone of 350° C. for 200 hours to obtain a gadolinium barium copper oxide superconducting block material.

[0089] Example 3

[0090] See also Figure 1-Figure 4

[0091] 1. Preparation of BaCuO2 powder

[0092] One mole of BaCO3 is mixed with one mole of CuO powder and BaCuO2 powder is prepared by a solid state reaction method.

[0093] 2. Pretreatment of multi-domain samples

[0094] A number of multi-domain gadolinium barium copper oxide superconducting blocks are cut, roughly ground, finely ground, polished, and pre-processed into semi-cylinders.

[0095] 3. Pressing high temperature solder blanks

[0096] 1 mol of analytically pure Gd2O3 and 1.2 mol of BaCuO2 powder are mixed to prepare a mixed powder; the mixed powder is added into a ball mill and mixed evenly, and the mixed powder is placed in a mold and pressed into a high-temperature solder blank.

[0097] 4. Pressing ring blocks

[0098] 1 mol of analytically pure Gd2O3 and 1.2 mol of BaCuO2 powder are mixed to prepare a mixed powder; the mixed powder is added to a ball mill and mixed evenly, and is placed in a ring mold and pressed into an inner diameter equal to that of a solid phase block.

[0099] 5. Prepare liquid source precursor powder

[0100] Mix 1 mol of analytically pure Y2O3, 13 mol of CuO powder and 8 mol of BaCuO2 powder evenly to serve as the liquid source precursor powder;

[0101] 6. Pressing the liquid source precursor block

[0102] The liquid source precursor powder is pressed into a cylinder having a diameter larger than the outer diameter of the annular compact to serve as a liquid source precursor block.

[0103] 7. Press the support block

[0104] The Yb2O3 powder is pressed into a cylinder with the same diameter as the liquid source precursor block as a support block.

[0105] 8. Blank assembly

[0106] The high-temperature solder is cut and placed between two multi-domain solid phase blocks as high-temperature solder. The annular green block is put on the periphery of the multi-domain solid phase as a solid phase block. MgO single crystal crystal, support block, liquid source precursor block, solid phase precursor block, and NdBariumCuO seed crystal block are placed in sequence from bottom to top on the upper surface of the Al2O3 gasket to assemble into a green body.

[0107] 9. Infiltration welding growth of single domain gadolinium barium copper oxide bulk material

[0108] The temperature was raised to 900°C at a heating rate of 120°C per hour, kept at this temperature for 20 hours, then raised to 1056°C at a heating rate of 60°C per hour, kept at this temperature for 2 hours, then cooled to 1035°C at a cooling rate of 60°C per hour, slowly cooled to 1015°C at a cooling rate of 0.4°C per hour, and naturally cooled to room temperature in the furnace to obtain a single-domain gadolinium barium copper oxide block.

[0109] 10. Oxygen treatment

[0110] The gadolinium barium copper oxide block is placed in a quartz tube furnace and slowly cooled for 200 hours in a circulating oxygen atmosphere at a temperature zone of 400° C. to obtain a gadolinium barium copper oxide superconducting block.

[0111] Technical Effects of Embodiments

[0112] See also Figure 5-Figure 7

[0113] Figure 5 As shown, the superconducting critical transition temperature curve at the weld of the single-domain gadolinium barium copper oxide superconducting bulk material grown by infiltration welding is displayed. From the figure, it can be seen that the starting critical transition temperature of the sample welded by this method is about 90.6K, which means that it has the critical temperature performance of the single-domain gadolinium barium copper oxide superconducting bulk material prepared by the traditional method.

[0114] Figure 6 As shown, the XRD pattern of the surface of the single-domain gadolinium barium copper oxide superconducting bulk material prepared by melt infiltration welding growth is shown. From the XRD spectrum of the surface of the sample welding growth, it can be seen that the surface of the sample using this welding has only 00L (L=3, 4, 5, 6, 7, 9). This result is consistent with the result of the sample prepared by the traditional method, and it also further proves that this method can be used to grow gadolinium barium copper oxide superconducting bulk materials with good single-domain morphology.

[0115] Figure 7 As shown, the SEM morphology of the weld of the single-domain gadolinium barium copper oxide superconducting bulk material prepared by infiltration welding growth is shown. It can be clearly seen from the figure that at the welding point of the sample (marked with an ellipse in the figure), the high-temperature welding billet has been integrated with the solid phase billet, no obvious cracks appear, and the internal integrity of the result is well captured, without showing crack defects on the macro and micro scales, proving that this method can be used to weld and grow multi-domain samples.

[0116] This main method is mainly used to weld two or more multi-domain samples that have failed to grow. Under high temperature conditions, the solid-phase precursor block will generate a molten state, so the liquid source will infiltrate into the solid-phase blank under the action of the seed crystal and complete the growth. It can also be used to weld small-sized superconducting blocks. Under high temperature conditions, the solid-phase precursor block will generate a molten state, so the liquid source will infiltrate into the solid-phase blank under the action of the seed crystal and grow into a large-sized superconducting block.

Claims

1. A method for growing a single-domain gadolinium barium copper oxide superconducting bulk material by infiltration welding, characterized in that: It consists of the following steps: S1, prepare BaCuO2 powder BaCO3 and CuO powder are mixed in a molar ratio of 1:1 to prepare BaCuO2 powder by a solid state reaction method; S2, Pretreatment of multi-domain samples Cutting a plurality of multi-domain gadolinium barium copper oxide superconducting blocks, and pre-processing such as rough grinding, fine grinding, and polishing into semi-cylinders, wherein the semi-cylinders are called solid phase blocks; S3, Pressed high temperature solder billet Gd2O3 and BaCuO2 powders are mixed in a molar ratio of 1:1.2 to prepare a mixed powder; the mixed powder is added into a ball mill and mixed evenly, and the mixed powder is placed in a mold and pressed into a high-temperature solder blank; S4, pressed ring-shaped block Gd2O3 and BaCuO2 powders are mixed in a molar ratio of 1:1.2 to prepare a mixed powder; the mixed powder is added to a ball mill and mixed evenly, and the mixed powder is placed in a ring mold and pressed into a ring-shaped block having an inner diameter equal to that of the solid phase block; S5, preparation of liquid source precursor powder Y2O3, CuO powder and BaCuO2 powder are mixed uniformly in a molar ratio of 1:(4+6x):(2+4x) as liquid source precursor powder, wherein 1 is between 1.0 and 2.0; S6, suppressed liquid source precursor block Pressing the liquid source precursor powder into a cylinder having a diameter greater than the outer diameter of the annular compact to serve as a liquid source precursor block; S7, pressed support block The Yb2O3 powder is pressed into a cylinder with the same diameter as the liquid source precursor block as a support block; S8, blank assembly The high temperature solder in S3 is cut and placed between the two solid phase blocks in S2 as the high temperature solder, the annular blank in S4 is placed around the two solid phase blocks as the solid phase precursor block, and the MgO single crystal, the support block in S7, the liquid phase source precursor block in S6, the solid phase precursor block, and the NdBariumCuO seed crystal block are placed in order from bottom to top on the upper surface of the Al2O3 gasket to assemble into a blank; S9, single domain gadolinium barium copper oxide bulk material grown by infiltration welding The assembled green body is placed in a tubular furnace, heated to 900°C at a heating rate of 100-150°C per hour, kept at this temperature for 20 hours, then heated to 1050-1065°C at a heating rate of 40-80°C per hour, kept at this temperature for 1-2.5 hours, then cooled to 1030-1040°C at a cooling rate of 50-80°C per hour, then slowly cooled to 1010-1040°C at a cooling rate of 0.1-1°C per hour, and naturally cooled to room temperature with the furnace to obtain a gadolinium barium copper oxide block material; S10, oxygen treatment The gadolinium barium copper oxide block is placed in a quartz tube furnace and slowly cooled for 200 hours in a circulating oxygen atmosphere at a temperature range of 440 to 350° C. to obtain a gadolinium barium copper oxide superconducting block.

2. The method for growing a single-domain Gd-Ba-Cu-O superconducting bulk material by infiltration welding according to claim 1, characterized in that: In S2, a number of multi-domain Gd-Barium Copper Oxide blocks are cut and classified into two halves or three halves according to the growth failure conditions.

3. The method for growing a single-domain Gd-Ba-Cu-O superconducting bulk material by infiltration welding according to claim 1, characterized in that: In S3, after the mixed powder is evenly mixed, it is placed in a cylindrical mold and pressed into a high-temperature welding block having a diameter larger than that of the solid phase block.

4. The method for growing a single-domain Gd-Ba-Cu-O superconducting bulk material by infiltration welding according to claim 1, characterized in that: Further, in S4, when the annular block is pressed, the inner diameter is equal to that of the solid phase block, and the difference between the outer diameter and the inner diameter is between 10-30 mm.

5. The method for growing a single-domain Gd-Ba-Cu-O superconducting bulk material by infiltration welding according to claim 1, characterized in that: In S5, x is preferably 1.

5.

6. The method for growing a single-domain Gd-Ba-Cu-O superconducting bulk material by infiltration welding according to claim 1, characterized in that: In S9, the assembled blank is placed in a tubular furnace, heated to 900°C at a heating rate of 120°C per hour, kept at this temperature for 20 hours, then heated to 1056°C at a heating rate of 60°C per hour, kept at this temperature for 2 hours, then cooled to 1035°C at a cooling rate of 60°C per hour, slowly cooled to 1015°C at a cooling rate of 0.4°C per hour, and naturally cooled to room temperature with the furnace to obtain a single-domain gadolinium barium copper oxide block.

Images