Sample preparation method for in-situ detection of Bi-system superconducting wire core wire cracks
The silver cover of Bi-type superconducting wire is removed by electrochemical methods, which solves the problem of core wire damage in the prior art, and achieves the accuracy and mechanical properties of the core wire cracks that are not damaged.
Patent Information
- Application Number
- CN202510615781.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2025-07-18
AI Technical Summary
The prior art can easily damage the core wire when removing the silver cover on the surface of Bi-type superconducting wire, making it difficult to accurately observe internal cracks and judge its authenticity.
The outer peripheral half of the Bi-type superconducting wire is sealed with tape, and the unsealed silver cover is powered on in the silver nitrate solution by electrochemical methods. By controlling the length and current density of the graphite plate, the uniform dissolution of the silver cover is achieved, and the cover support of the core wire is retained.
The core wire cracks of Bi-type superconducting wire are realized without loss, avoid core wire damage, maintain the mechanical properties of the sample, ensure the accuracy of observation and the stress-free removal of the silver cover.
Smart Images
Figure CN120333948A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of high-temperature superconducting wire materials, and in particular relates to a sample preparation method for in-situ detection of cracks in Bi-based superconducting wire cores. Background Art
[0002] High-temperature superconducting wire materials exhibit great potential in frontier fields such as superconducting cables, superconducting current limiters, superconducting magnets, superconducting transformers, and magnetic confinement fusion, hadron colliders, etc., due to their zero-resistance characteristics, excellent upper critical field, and extremely high superconducting transition temperature.
[0003] In order to further improve the current-carrying capacity of superconducting wire materials, it is particularly crucial to implement precise in-situ analysis. In Bi-based superconducting wire materials, tiny cracks and defects are the primary factors currently limiting their current-carrying capacity. To effectively observe these defects, the existing technology completely removes the silver sheath on the surface of Bi-based superconducting wire materials to expose the ceramic superconducting wire cores for direct observation. However, due to the low strength of the ceramic wire cores themselves, they are extremely prone to breakage after the silver layer is removed, making it difficult to accurately observe the crack defects inside the wire cores; even if cracks are observed, it is difficult to determine whether they originally existed in the wire cores or were newly generated during the sample preparation process.
[0004] Therefore, in order to accurately observe the cracks in superconducting wire cores and guide subsequent process optimization, it is urgent to explore an innovative sample preparation method. Summary of the Invention
[0005] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a sample preparation method for in-situ detection of cracks in Bi-based superconducting wire cores. This sample preparation method seals half of the outer periphery of the Bi-based superconducting wire, and uses an electrochemical method to remove the non-sealed half sheath of the Bi-based superconducting wire, avoiding damage to the wire cores inside the Bi-based superconducting wire. At the same time, the superconducting sample retains the support of the half sheath, ensuring that the superconducting sample has high mechanical properties, and solving the problem that the wire cores are easily damaged during sample preparation in the prior art.
[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a sample preparation method for in-situ detection of cracks in Bi-based superconducting wire cores, characterized in that this sample preparation method includes the following steps:
[0007] Step 1: Seal half of the outer periphery of the Bi-based superconducting wire with tape;
[0008] Step 2: Connect the Bi-based superconducting wire sealed on half of its surface in Step 2 as the anode to the positive pole of a DC power supply, connect a graphite plate as the cathode to the negative pole of the DC power supply, and then insert the cathode and anode into a silver nitrate solution and energize until the wire cores are exposed on the surface of the Bi-based superconducting wire to obtain a superconducting sample.
[0009] The above-mentioned method for preparing a sample for in-situ detection of cracks in Bi-based superconducting wire cores is characterized in that, before sealing the Bi-based superconducting wire, degreasing, cleaning, dehydration and drying are carried out.
[0010] The above-mentioned method for preparing a sample for in-situ detection of cracks in Bi-based superconducting wire cores is characterized in that the sheath material of the Bi-based superconducting wire in step one is silver or silver alloy.
[0011] The above-mentioned method for preparing a sample for in-situ detection of cracks in Bi-based superconducting wire cores is characterized in that in step two, the length of the graphite plate is 1 cm to 2 cm longer than the length of the Bi-based superconducting wire, and the width of the graphite plate is 2 to 3 times the width of the Bi-based superconducting wire.
[0012] The present invention controls the length and width settings of the graphite plate to achieve uniform dissolution of the silver on the surface of the Bi-based superconducting wire.
[0013] The above-mentioned method for preparing a sample for in-situ detection of cracks in Bi-based superconducting wire cores is characterized in that in step two, the concentration of the silver nitrate solution is 0.1 mol / L to 0.5 mol / L.
[0014] The present invention controls the concentration of the silver nitrate solution to uniformly dissolve the silver sheath of the Bi-based superconducting wire and reduce the influence of the silver nitrate solution on the core wire.
[0015] The above-mentioned method for preparing a sample for in-situ detection of cracks in Bi-based superconducting wire cores is characterized in that in step two, the current density of the DC power supply is 5 A / dm 2 ~10 A / dm 2 。
[0016] The present invention controls the current density to dissolve the silver sheath of the Bi-based superconducting wire more uniformly, so that when preparing a sample of the Bi-based superconducting tape, the core wires are evenly exposed everywhere.
[0017] The present invention has the following advantages compared with the prior art:
[0018] 1. The present invention seals half of the outer periphery of the Bi-based superconducting wire, uses an electrochemical method to remove the non-sealed half sheath of the Bi-based superconducting wire, exposes the core wire for crack observation, and at the same time retains the half-sheath support of the superconducting sample, ensuring that the superconducting sample has high mechanical properties and can avoid damage to the core wire inside the Bi-based superconducting wire.
[0019] 2. The present invention adopts an electrochemical method in the process of removing the metal sheath. By using a silver nitrate solution as an electrolyte, a graphite plate as a cathode, and a Bi-based superconducting wire as a positive electrode, the current is made to flow from the anode through the electrolyte to the cathode under power-on conditions. The anode undergoes an oxidation-reduction reaction to convert the silver sheath on the surface into silver ions, which dissolve into the solution, thereby achieving stress-free removal of the silver sheath, avoiding the stress damage to the core wire caused by the mechanical force method used in the prior art to remove the sheath. At the same time, the use of a silver nitrate solution can avoid the introduction of impurities.
[0020] 3. The present invention can realize in-situ observation of lossless core wires, thereby more directly obtaining the current limiting mechanism of Bi-based superconducting wires.
[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a physical picture of the Bi-based superconducting wire strip that is energized for different time periods in Example 1 of the present invention. DETAILED DESCRIPTION
[0023] Example 1
[0024] The sample preparation method of this embodiment comprises the following steps:
[0025] Step 1: Cut the Bi-based superconducting wire strip, soak it in a metal cleaning agent aqueous solution at a temperature of 40° C. for 30 minutes to remove oil, wash it with water at 40° C., dehydrate it with ethanol and dry it with a hair dryer, and then seal the half surface of the outer peripheral side of the Bi-based superconducting wire strip with an adhesive tape; the sheath material of the Bi-based superconducting wire strip is silver or a silver alloy;
[0026] Step 2: Use the Bi-based superconducting wire strip after half-surface sealing in step 2 as an anode connected to the positive electrode of a DC power supply, and use the graphite plate as a cathode connected to the negative electrode of a DC power supply, and then extend the cathode and anode into a silver nitrate solution with a concentration of 0.1 mol / L, and pass a current density of 5 A / dm 2 The current is supplied until black core wires leak out from the surface of the Bi-based superconducting wire strip, thereby obtaining a superconducting sample; the length of the graphite plate is greater than 1 cm of the length of the Bi-based superconducting wire, and the width of the graphite plate is twice the width of the Bi-based superconducting wire.
[0027] During the sample preparation process, the exposed half surface of the Bi-based superconducting wire tape was observed. Figure 1As shown, through the sample preparation method of this embodiment, a superconducting sample with a silver sheath carrier can be obtained, which is convenient for in-situ observation. The current-carrying performance of the superconducting sample before the sample preparation method treatment of the Bi-based superconducting wire strip and after the treatment of this embodiment was measured, and it was found that the current-carrying performance of the superconducting sample did not decrease, indicating that the sample preparation method of this embodiment will not damage the core wire. The mechanical properties of the superconducting sample were tested, and the tensile strength reached more than 60 MPa, indicating that the remaining silver sheath can provide sufficient support for the core wire, avoiding damage to the core wire caused by sample movement, observation or other treatments, thus ensuring the accuracy of the core wire microstructure in in-situ observation.
[0028] Example 2
[0029] The sample preparation method of this embodiment includes the following steps:
[0030] Step 1: Cut the Bi-based superconducting wire strip, soak it in an aqueous solution of a metal cleaning agent at a temperature of 50 °C for 30 minutes to remove oil, wash it with water at 50 °C, dehydrate it with ethanol and dry it with a hair dryer, and then seal half of the outer peripheral side of the Bi-based superconducting wire strip with tape; the sheath material of the Bi-based superconducting wire strip is silver or silver alloy;
[0031] Step 2: Connect the Bi-based superconducting wire after half-sealing in Step 2 as the anode to the positive pole of a DC power supply, connect a graphite plate as the cathode to the negative pole of the DC power supply, then immerse the cathode and anode in a silver nitrate solution with a concentration of 0.5 mol / L, and pass a current with a current density of 10 A / dm 2 until a black core wire appears on the surface of the Bi-based superconducting wire strip to obtain a superconducting sample; the length of the graphite plate is 2 cm longer than the length of the Bi-based superconducting wire, and the width of the graphite plate is 3 times the width of the Bi-based superconducting wire.
[0032] The current-carrying performance of the Bi-based superconducting wire strip before the sample preparation method treatment and the superconducting sample after the treatment of this embodiment was measured, and it was found that the current-carrying performance of the superconducting sample did not decrease, indicating that the sample preparation method of this embodiment will not damage the core wire, and at the same time, the tensile strength of the superconducting sample reached more than 60 MPa.
[0033] Example 3
[0034] The sample preparation method of this embodiment includes the following steps:
[0035] Step 1: Cut the Bi-based superconducting wire strip, soak it in an aqueous solution of a metal cleaning agent at a temperature of 45 °C for 30 minutes to remove oil, wash it with water at 45 °C, dehydrate it with ethanol and dry it with a hair dryer, and then seal half of the outer peripheral side of the Bi-based superconducting wire strip with tape; the sheath material of the Bi-based superconducting wire strip is silver or silver alloy, and artificial crack manufacturing is carried out before cutting the Bi-based superconducting wire strip;
[0036] Step 2: Take the Bi-based superconducting wire after half-surface sealing in Step 2 as the anode and connect it to the positive electrode of the DC power supply. Take a graphite plate as the cathode and connect it to the negative electrode of the DC power supply. Then insert the cathode and anode into a silver nitrate solution with a concentration of 0.3 mol / L, and pass a current with a current density of 8 A / dm 2 to obtain a superconducting sample until black core wires leak out on the surface of the Bi-based superconducting wire strip; the length of the graphite plate is 1.5 cm longer than the length of the Bi-based superconducting wire, and the width of the graphite plate is 2.5 times the width of the Bi-based superconducting wire.
[0037] Before the Bi-based superconducting wire strip is processed by the sample preparation method and after the superconducting sample is processed in this embodiment, the current-carrying performance tests are both carried out. It is measured that the current-carrying performance of the superconducting sample has not decreased, indicating that the sample preparation method in this embodiment will not damage the core wires. At the same time, the tensile strength of the superconducting sample reaches more than 60 MPa.
[0038] The above is only a preferred embodiment of the present invention, and does not impose any limitation on the present invention. Any simple modification, change, and equivalent structural transformation made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims
1. A sample preparation method for in-situ detecting cracks in Bi-based superconducting wire core filaments, characterized in that, The sample preparation method includes the following steps: Step 1: Seal half of the outer periphery of the Bi-based superconducting wire with tape; Step 2: Use the Bi-based superconducting wire with half of its periphery sealed in Step 1 as the anode and connect it to the positive pole of the DC power supply, use a graphite plate as the cathode and connect it to the negative pole of the DC power supply, then insert the cathode and anode into the silver nitrate solution and energize until the core wire is exposed on the surface of the Bi-based superconducting wire to obtain a superconducting sample.
2. The sample preparation method for in-situ detecting cracks in Bi-based superconducting wire core filaments according to claim 1, characterized in that Before sealing in Step 1, the Bi-based superconducting wire is degreased, cleaned, dehydrated and dried.
3. A sample preparation method for in-situ detecting cracks in Bi-based superconducting wire core filaments according to claim 1, characterized in that, The sheath material of the Bi-based superconducting wire in Step 1 is silver or silver alloy.
4. A sample preparation method for in-situ detecting cracks in Bi-based superconducting wire core filaments according to claim 1, characterized in that, In Step 2, the length of the graphite plate is 1 cm to 2 cm longer than the length of the Bi-based superconducting wire, and the width of the graphite plate is 2 to 3 times the width of the Bi-based superconducting wire.
5. A sample preparation method for in-situ detecting cracks in Bi-based superconducting wire core filaments according to claim 1, characterized in that, In Step 2, the concentration of the silver nitrate solution is 0.1 mol / L to 0.5 mol / L.
6. A sample preparation method for in-situ detecting cracks in Bi-based superconducting wire core filaments according to claim 1, characterized in that, The current density of the DC power supply described in Step 2 is 5 A / dm 2 ~10 A / dm 2 .