CN111009746A - Welding method of superconducting thin film material - Google Patents
Welding method of superconducting thin film material Download PDFInfo
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- CN111009746A CN111009746A CN201911294989.0A CN201911294989A CN111009746A CN 111009746 A CN111009746 A CN 111009746A CN 201911294989 A CN201911294989 A CN 201911294989A CN 111009746 A CN111009746 A CN 111009746A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
- H01R4/58—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation characterised by the form or material of the contacting members
- H01R4/68—Connections to or between superconductive connectors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
- H01R43/02—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors for soldered or welded connections
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Abstract
The invention discloses a welding method of a superconducting thin film material, which comprises the following steps: s1, covering a silver coating layer of the superconducting bare tape with a coating layer, wherein the coating layer contains metal, and the resistivity of the metal is 10‑8Omega m magnitude and below; s2, adhering and fixing the welding parts of the adjacent superconductive bare belts; s3, placing the welding position at the temperature of 20-300 ℃ and under the pressure of 0.02-2MPa, and filling the welding flux in the joint to obtain the bare belt body. The silver coating layer still can keep the original protection effect, so that the YBCO layer is not easy to be damaged, and the performance of the welded bare belt body is improved.
Description
Technical Field
The invention relates to the field of superconducting materials, in particular to a welding method of a superconducting thin film material.
Background
With the wide research and application of superconducting technology in various fields, the requirement on the length of a superconducting tape is higher and higher, the length of the superconducting tape cannot meet the actual requirement at present, the superconducting tape welding becomes a trend, the superconducting bare tape welding can reduce the thickness of a joint part, the duty ratio of a power-on conductor is effectively improved, the appearance is beautified, and the superconducting tape welding is popular, so that the higher requirement is provided for the superconducting tape welding.
Patent CN 104167487A' ReBa2Cu3O7-δThe connection process of high-temperature superconducting thin film strips and a pressure heating system thereof, and the patent CN107799917A, a low-resistance connection device of REBCO high-temperature superconducting strips and a manufacturing method thereof, all mention that superconducting thin film welding can cause oxygen loss of a superconducting layer due to high temperature, and the welding of a superconducting bare strip is carried out by adopting a lower-temperature welding flux. In practical application, the superconducting bare tape needs to be packaged through a soldering process after being welded, so that the melting point temperature of the brazing filler metal for welding the superconducting bare tape needs to be higher than the temperature of the brazing filler metal for soldering and packaging. The bare strip welding is actually the welding between the silver coating and the silver coating, and when the welding temperature is higher, the more the silver is dissolved in a brazing seam, intermetallic compounds are generated, so that the YBCO layer loses the protection of the silver coating and then is damaged, and finally, the performance of the welded superconducting strip is reduced.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a welding method of a superconducting thin film material, which can improve the welding performance.
In order to solve the technical problem, the invention provides a welding method of a superconducting thin film material, which comprises the following steps: s1, covering a silver coating layer of the superconducting bare tape with a coating layer, wherein the coating layer contains metal, and the resistivity of the metal is 10-8Omega m magnitude and below; s2, adhering and fixing the welding parts of the adjacent superconductive bare belts; s3, placing the welding position at the temperature of 20-300 ℃ and under the pressure of 0.02-2MPa, and filling the welding flux in the joint to obtain the bare belt body.
Further, after step S3, the method further includes the following steps:
s4, covering the upper surface and the lower surface of the bare belt body with plating layers;
s5, coating metal layers on the upper surface and the lower surface of the bare belt body;
and S6, welding the bare belt body and the two metal layers.
Further, the metal is copper, a copper alloy, silver or a silver alloy.
Further, step S1 includes the following steps:
s11, covering a silver coating layer of the superconducting bare tape with a coating layer, wherein the coating layer contains metal, and the resistivity of the metal is 10-8Omega m magnitude and below;
and S12, passivating the coating of the superconducting bare tape.
Further, step S2 includes the following steps:
s31, polishing the surface of the plating layer;
s32, cleaning the surface of the superconducting bare belt;
s33, coating soldering flux on the surface of the plating layer;
and S34, jointing and fixing the welding parts of the adjacent superconducting bare belts.
Further, step S4 includes the following steps:
s41, respectively cleaning the bare belt body and the metal layer;
s42, covering the upper surface and the lower surface of the bare belt body with plating layers;
s43, respectively coating soldering flux on the plating layer and the metal layer;
and S44, respectively preheating the bare belt body and the metal layer.
Further, in step S1, the silver plating layer of the bare superconducting tape is covered with the plating layer, and the other opposite surface of the bare superconducting tape is covered with the plating layer.
Furthermore, the thickness of the coating is 1-10 um.
Further, the plating layer is covered on the surface of the silver plating layer by electroplating.
It is still another object of the present invention to provide a superconducting tape manufactured by the welding method of the superconducting thin film material.
The invention has the beneficial effects that:
when the coating is covered on the surface of the silver coating, the silver coating still can keep the original protective action of the silver coating, so that the YBCO layer is not easy to be damaged, and the performance of the welded bare belt body is improved; the silver coating and the superconducting layer are protected by the coating, so that the current loss is reduced, and the welding performance is improved; meanwhile, the bending performance and the mechanical strength of the welding joint are improved by utilizing the welding of the plating layer and the welding flux.
Drawings
FIG. 1 is a schematic view of the welding of a bare superconducting tape according to the present invention;
fig. 2 is a schematic view of the welding of the bare belt body and the metal layer in the present invention.
Detailed Description
The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.
An embodiment of the welding method of the superconducting thin film material of the invention specifically comprises the following steps:
s10, cleaning the surface of the superconducting bare belt to remove impurities and oil stains on the surface of the superconducting bare belt, so that the attachment of a plating layer is facilitated, the weldability of the solder at the joint and the belt body 11 is enhanced, and the mechanical strength of the welded joint can be improved;
s11, covering a silver coating layer of the superconducting bare tape with a coating layer, wherein the coating layer contains metal, and the resistivity of the metal is 10-8In the order of omega m and below, the coating can be attached to the surface of the silver coating by electroplating and the like in the embodiment, so as to be convenient for operation and implementation;
s12, passivating the coating of the superconducting bare tape, wherein the passivation of the coating can prevent the coating from being oxidized so as to ensure the performance of the coating;
s21, polishing the surface of the plating layer to remove a passivating agent attached to the surface of the plating layer and an oxidation layer generated by oxidation of the surface of the plating layer so as to completely expose the plating layer and facilitate later-stage welding;
s22, cleaning the surface of the superconducting bare belt to clean the polished impurities and particles so as to facilitate the adhesion of the soldering flux, wherein in the embodiment, cleaning solutions such as alcohol or acetone can be selected for cleaning;
s23, coating the surface of the plating layer with the soldering flux, and removing oxides by using the soldering flux, so that the surface tension of the welded material is reduced, and the mechanical strength of a welding joint is improved;
s24, adhering and fixing the welding parts of the adjacent superconductive bare belts;
s3, placing the welding part at the temperature of 20-300 ℃ and under the pressure of 0.02-2MPa, and filling the welding flux in the joint to obtain a bare belt body;
s41, cleaning the bare belt body and the metal layer respectively to remove impurities and oil stains on the surfaces of the bare belt body and the metal layer, thereby facilitating the adhesion of the plating layer and enhancing the weldability between the solder at the joint and the belt body 11, in this embodiment, cleaning solutions such as alcohol or acetone can be selected for cleaning;
s42, covering the upper surface and the lower surface of the bare belt body with plating layers;
s43, respectively coating soldering flux on the plating layer and the metal layer, removing oxides by using the soldering flux, and reducing the surface tension of the welded material so as to improve the mechanical strength of the welded joint;
s44, preheating the bare belt body and the metal layer respectively, wherein the bare belt body and the metal layer are preheated before soldering and packaging, the mechanical strength of a welding joint can be improved, and the preheating temperature can be selected according to the type of the selected solder;
s5, coating metal layers on the upper surface and the lower surface of the bare belt body to form the required superconducting belt material;
s6, welding the bare belt body and the two metal layers, wherein the bare belt body and the two metal layers can be placed in a tin bath during welding to ensure the continuity during welding; and meanwhile, the tin bath is used for facilitating the positioning of the bare belt body and the metal layer so as to improve the welding effect of the bare belt body and the metal layer.
After being welded, the superconducting bare belts need to be packaged through a soldering process to form the superconducting tapes. The melting point of the solder is required to be higher than that of the solder during soldering and packaging when the superconducting bare tape is soldered, so that the temperature selection range of the solder is small. The surface of the silver coating of the bare belt is coated with a coating which contains metal and has the resistivity of 10-8In the order of Ω · m or less. The silver coating can be coated onThe silver coating is protected during the welding process, so that the mechanical strength of the welding joint can be improved. In the prior art, the bare strip is actually welded with a silver coating in the welding process, and the thickness of the silver coating is generally 1-3 um. When the welding temperature is too high or during the welding time, the more silver is dissolved in the brazing seam, metal compounds are generated, so that the YBCO layer loses the protection of the silver layer and is damaged. Therefore, the quality of the welded joint is unstable and the yield of the product is low.
Referring to fig. 1, when the silver plating layer is coated on the surface of the silver plating layer, the silver plating layer still maintains its original protective function, so that the YBCO layer is not easily damaged. The silver coating and the superconducting layer are protected by the coating, so that the current loss is reduced, and the welding performance is improved. Meanwhile, the bending performance and the mechanical strength of the welding joint are improved by utilizing the welding of the plating layer and the welding flux. Compared with a soft soldering process for increasing the thickness of the silver plating layer in the prior art, the process flow is simplified by covering the surface of the silver plating layer with the plating layer, and meanwhile, the processing cost is reduced.
Meanwhile, the thickness of the coating covering the surface of the silver coating is 1-10um, which does not have obvious influence on the total thickness of the superconducting tape.
In addition, both surfaces of the superconducting bare tape may be coated with a plating layer, that is, the plating layer may be coated on the surface of the silver plating layer and the surface opposite to the silver plating layer. The back that the cladding material can be taken the superconducting bare in the welded in-process is protected, simultaneously, after the welding is accomplished, the cladding material all has certain guard action to the bare area of superconducting and welded joint department.
Referring to fig. 2, when the bare belt body is soldered and packaged, the upper surface and the lower surface of the bare belt body are covered with the plating layers, so that the peeling force during welding is enhanced, thereby facilitating the welding of the bare belt body and the metal layer and improving the yield of the superconducting tape. Meanwhile, after the surface of the bare belt body is covered with the coating, the bending resistance, torsion resistance and tensile resistance of the superconducting belt material can be improved. In addition, the cladding material that covers on the surface of the naked area body all has certain guard action to the naked area body and welded joint department, also is convenient for the storage and the transportation of the naked area body simultaneously.
The metal contained in the plating layer can be selected from copper, copper alloy, silver or silver alloy, so that the plating layer containing the metal is utilized to enhance the welding performance, and the welding performance is improved.
When the thickness of copper covered on the surface of the silver coating is 3um, the bandwidth of the superconducting bare tape is 4mm, and the thickness of the superconducting bare tape is 65um, the current loss and the resistance at the welding joint can be obtained when welding is carried out in the overlapping mode according to the following steps. The method comprises the following specific steps:
s10, taking a superconducting bare belt with the belt width of 4mm and the thickness of 65um, and cleaning the surface of the superconducting bare belt;
s11, electroplating copper on the silver plating layer of the superconducting bare belt, wherein the thickness of the copper is 3 um;
s12, passivating the copper coated on the surface of the superconducting bare belt;
s21, polishing the surface of the plating layer to remove a passivating agent attached to the surface of the copper and an oxide layer generated by oxidation of the surface of the copper so as to completely expose the copper;
s22, cleaning the surface of the superconducting bare belt to clean the polished impurities and particles;
s23, coating soldering flux on the surface of the plating layer;
s24, jointing and fixing the welding parts of the adjacent superconducting bare belts, wherein the lapping length of the two adjacent superconducting bare belts is 6 cm;
s3, placing the welding position at the temperature of 20-300 ℃ and under the pressure of 0.02-2MPa, and filling the welding flux in the joint to obtain the bare belt body.
The superconducting bare belt obtained by the welding method comprises at least two belt bodies, wherein each belt body comprises a silver coating layer covered on the surface of the belt body, and a first coating layer is covered on the surface of the silver coating layer; the first coating layer contains metal with resistivity of 10-8Omega m magnitude and below; the area body can be fixed in proper order through the welding, and the first cladding material of adjacent area body sets up relatively, and first cladding material and solder contact. The metal includes copper, copper alloy, silver or silver alloy.
In addition, the superconducting tape comprises a superconducting bare tape and two metal layers coated on the surface of the superconducting bare tapeThe two surfaces of the bare conducting belt are covered with second coating layers, the second coating layers comprise metal, and the resistivity of the metal is 10-8Omega m magnitude and below; the two metal layers are respectively attached to the two second plating layers, and the superconducting bare belt can be fixed with the two metal layers through welding. The metal includes copper, copper alloy, silver or silver alloy.
TABLE 1 Current loss and resistance of welded joints when the coating is copper
When the thickness of the silver covered on the surface of the silver coating is 3um, the bandwidth of the superconducting bare tape is 4mm, and the thickness of the superconducting bare tape is 65um, the current loss and the resistance at the welding joint can be obtained when welding is carried out in the overlapping mode according to the following steps. The method comprises the following specific steps:
s10, taking a superconducting bare belt with the belt width of 4mm and the thickness of 65um, and cleaning the surface of the superconducting bare belt;
s11, silver is electroplated on the silver coating of the superconducting bare belt, and the thickness of the silver is 3 um;
s12, passivating the silver coated on the surface of the superconducting bare belt;
s21, polishing the surface of the plating layer to remove a passivating agent attached to the silver surface and an oxide layer generated by oxidation of the silver surface so as to completely expose the silver;
s22, cleaning the surface of the superconducting bare belt to clean the polished impurities and particles;
s23, coating soldering flux on the surface of the plating layer;
s24, jointing and fixing the welding parts of the adjacent superconducting bare belts, wherein the lapping length of the two adjacent superconducting bare belts is 6 cm;
s3, placing the welding position at the temperature of 20-300 ℃ and under the pressure of 0.02-2MPa, and filling the welding flux in the joint to obtain the bare belt body.
TABLE 2 Current loss and resistance of the welded joints when the coating is silver
It can be seen from table 1 that when the surface of the silver plating layer is covered with copper, the current loss of the welded joint of the adjacent bare superconducting tapes is small, and the resistance at the welded joint is also small. Therefore, the copper layer covered on the surface of the silver plating layer can reduce the loss of current, stabilize the silver plating layer better and protect the superconducting layer.
As can be seen from table 2, when the surface of the silver plating layer is covered with silver, the current loss of the welded joint of the adjacent bare superconducting tapes is small, and the resistance at the welded joint is also small. Therefore, the copper layer covered on the surface of the silver plating layer can reduce the loss of current, stabilize the silver plating layer better and protect the superconducting layer.
When comparing tables 1 and 2, the surface of the silver plated layer was covered with silver, the magnitudes of current loss and resistance at the weld joint were smaller than those when the surface of the silver plated layer was covered with copper. Since silver itself has a lower resistivity than copper, when the surface of the silver plated layer is covered with silver, the resistance at the solder joint is lower than when the surface of the silver plated layer is covered with copper. When the surface of the silver plating layer is covered with silver, the silver layer can not only protect the silver plating layer covered under the silver plating layer in the welding process, but also supplement the dissolving amount of the silver plating layer in a soldering seam through the silver layer so as to reduce the current loss at the welding seam.
The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.
Claims (10)
1. A method for welding superconducting thin film materials is characterized by comprising the following steps:
s1, covering a plating layer on the surface of the silver plating layer of the superconducting bare tape, wherein the plating layer contains metal, and the resistivity of the metal is 10-8Omega m magnitude and below;
s2, adhering and fixing the welding parts of the adjacent superconductive bare belts;
s3, placing the welding position at the temperature of 20-300 ℃ and under the pressure of 0.02-2MPa, and filling the welding flux in the joint to obtain the bare belt body.
2. The method for welding superconducting thin film materials of claim 1, further comprising the following steps after step S3:
s4, covering the upper surface and the lower surface of the bare belt body with plating layers;
s5, coating metal layers on the upper surface and the lower surface of the bare belt body;
and S6, welding the bare belt body and the two metal layers.
3. A method for welding superconducting thin film materials according to claim 1, wherein the metal is copper, a copper alloy, silver or a silver alloy.
4. The method for welding superconducting thin film materials of claim 1, wherein the step S1 comprises the steps of:
s11, covering a plating layer on the surface of the silver plating layer of the superconducting bare belt, wherein the plating layer contains metal, and the resistivity of the metal is 10-8Omega m magnitude and below;
and S12, passivating the coating of the superconducting bare tape.
5. The method for welding superconducting thin film materials of claim 1, wherein the step S2 comprises the steps of:
s21, polishing the surface of the plating layer;
s22, cleaning the surface of the superconducting bare belt;
s23, coating soldering flux on the surface of the plating layer;
and S24, jointing and fixing the welding parts of the adjacent superconducting bare belts.
6. The method for welding superconducting thin film materials of claim 2, wherein the step S4 comprises the steps of:
s41, respectively cleaning the bare belt body and the metal layer;
s42, covering the upper surface and the lower surface of the bare belt body with plating layers;
s43, respectively coating soldering flux on the plating layer and the metal layer;
and S44, respectively preheating the bare belt body and the metal layer.
7. The method for welding superconducting thin film materials of claim 1, wherein in step S1, the silver plating layer of the bare superconducting tape is coated with the plating layer, and the other opposite surface of the bare superconducting tape is coated with the plating layer.
8. A method of welding superconducting thin film materials according to claim 1, wherein the coating is coated to a thickness of 1-10 um.
9. A method of welding superconducting thin film materials according to claim 1, wherein the plating layer is coated on the surface of the silver plating layer by electroplating.
10. A superconducting tape produced by the method for welding a superconducting thin film material according to any one of claims 1 to 9.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114619131A (en) * | 2021-09-24 | 2022-06-14 | 上海交通大学 | Solderless welding joint and welding manufacturing method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114619131A (en) * | 2021-09-24 | 2022-06-14 | 上海交通大学 | Solderless welding joint and welding manufacturing method thereof |
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