EP0048880B1 - Procédé pour fixer les enroulements d'une bobine magnétique supraconductrice - Google Patents

Procédé pour fixer les enroulements d'une bobine magnétique supraconductrice Download PDF

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Publication number
EP0048880B1
EP0048880B1 EP81107230A EP81107230A EP0048880B1 EP 0048880 B1 EP0048880 B1 EP 0048880B1 EP 81107230 A EP81107230 A EP 81107230A EP 81107230 A EP81107230 A EP 81107230A EP 0048880 B1 EP0048880 B1 EP 0048880B1
Authority
EP
European Patent Office
Prior art keywords
winding
cement
annealing
putty
high temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP81107230A
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German (de)
English (en)
Other versions
EP0048880A1 (fr
Inventor
Fritz Dr. Assmus
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vacuumschmelze GmbH and Co KG
Original Assignee
Vacuumschmelze GmbH and Co KG
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Filing date
Publication date
Application filed by Vacuumschmelze GmbH and Co KG filed Critical Vacuumschmelze GmbH and Co KG
Publication of EP0048880A1 publication Critical patent/EP0048880A1/fr
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Publication of EP0048880B1 publication Critical patent/EP0048880B1/fr
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F6/06—Coils, e.g. winding, insulating, terminating or casing arrangements therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
    • H01F41/12—Insulating of windings
    • H01F41/122—Insulating between turns or between winding layers

Definitions

  • the invention relates to a method for fixing the turns of a superconducting magnetic winding, which is initially built up from preliminary conductor products and in which the superconducting properties are produced by reaction annealing of the finished winding.
  • Superconducting intermetallic compounds with A15 crystal structure such as the two-component compounds Nb 3 Sn and V 3 Ga or the ternary compound Nb 3 A1 o , 8 Ge 0 , 2 , have good superconducting properties and are distinguished by high critical values, ie by a high step temperature, a high critical current density and a high critical magnetic field.
  • the superconducting intermetallic compounds are generally very brittle, so that their manufacture in a form suitable for solenoids is difficult.
  • the general procedure today is to first of all provide a rod or wire made of the higher-melting element of the connection with a shell made of an alloy, which consists of a carrier metal and the lower-melting element of the connection or, if appropriate, several such elements.
  • a niobium wire is surrounded by a copper-tin-bronze sheath. A large number of these covered wires are then combined into a bundle.
  • a wire or a strip of an alloy matrix is thus obtained, in which a multiplicity of thread-shaped cores from the higher-melting element of the connection is embedded, for example a copper-tin wire with a large number of embedded niobium filaments.
  • a preliminary conductor product is then subjected to an annealing treatment in which the element or elements of the compound contained in the matrix diffuse into the cores of the higher-melting element and react with it to form the intermetallic compound (see e.g. DE-A-2044660).
  • Superconducting magnetic coils from such superconductors have hitherto generally been produced by two different processes (cf. e.g. DE-A-2837199 and 2840526).
  • the preliminary conductor product is wound onto a provisional winding body and then annealed to form the desired superconducting compound.
  • the superconductor produced in this way is unwound again from the provisional winding body and can then be wound, for example, into a magnetic coil.
  • the high brittleness of the superconducting intermetallic compounds there is a risk that cracks will occur in the intermetallic superconducting connections if the bending radius permitted for the completely reacted conductor is undershot and the superconducting properties are impaired accordingly.
  • the wind and react technique Another method is used, which is also referred to as the “wind and react technique”.
  • the coil body of the magnet to be provided with the winding is wound with the as yet unreacted conductor preliminary product and the entire magnet thus wound is then subjected to diffusion annealing. Since the intermetallic connection is only created in situ in the coil or winding, in this case the diffusion annealing is also called “in situ annealing”. This procedure avoids all difficulties in processing a brittle conductor material. However, the materials present in the coil during the diffusion annealing must withstand the required high temperatures for several hours, which, for example in the case of Nb 3 Sn, are around 700 ° C.
  • the conductor pre-product wrapped or wound with an insulation made of glass, ceramic or quartz threads has been wound onto a correspondingly high-temperature-resistant coil body and the coil windings are finally fixed only after the diffusion annealing, by covering the finished winding with suitable curable or solidifying organic materials upon cooling , for example epoxy resins or paraffin, preferably impregnated by vacuum impregnation (cf. DE-A-2546198 and 2837199).
  • the object of the invention is to manufacture of superconducting magnetic windings, the superconducting properties of which are produced by reaction annealing (in-situ annealing) of the finished winding.
  • the method according to the invention leads to a fixed fixation of the individual turns of the coil winding even before the reaction annealing and thus avoids the shape and position changes occurring in unfixed turns due to thermal expansion or contraction and their disadvantageous consequences. It has also been shown that the formation of carbon bridges is also avoided by the putty introduced into the winding. It is therefore no longer necessary to remove the sizes or the binders of the insulating materials from the winding before the annealing treatment.
  • Suitable putties are inorganic materials which, if necessary after prior mixing with water or other suitable inorganic liquids, are curable or otherwise harden or solidify and in the solidified state both at the high temperatures required for reaction annealing of, for example, about 700 ° C. at Nb 3 Sn as well as at the low temperatures required to bring about the superconducting state, for example the temperature of the liquid helium of 4.2 K, are stable.
  • the putties should also have good resistance to temperature changes so that no damage occurs in the winding even when the coil is repeatedly cooled to low temperatures. For similar reasons, the putties should not differ too much from the superconductor material with regard to their thermal expansion. Furthermore, good thermal conductivity of the cement is also advantageous for effective cooling of the coil winding. Unstable connections that release metals during reaction annealing should not be included in the kit, since the insulation of the winding would be impaired by the released metal.
  • a putty made from water glass (sodium silicate solution) and talcum (soapstone powder) has proven to be particularly suitable. This putty solidifies into a hard mass made of double silicates, which very well fulfills the aforementioned requirements.
  • a mixture of about 60% by weight of water glass and 40% by weight of talc is preferably used, which can still be processed well even after a long standing time.
  • the winding is first used to dry the cement of a heat treatment at a. first temperature of preferably 35 to 40 ° C and then to harden the putty a heat treatment at a second higher temperature, preferably about 100 to 120 ° C, subjected.
  • This two-stage heat treatment can be combined with the reaction annealing to a three-stage heat treatment.
  • a particularly stable winding structure can be obtained by first applying an insulating mat made of high-temperature resistant material, for example a glass fiber mat, to a high-temperature-resistant coil former, for example made of stainless steel, and then impregnating it with the putty, then applying the successive layers of the conductor winding and in each case with the putty are coated and finally the finished winding is surrounded by another high-temperature-resistant insulating mat, which is also to be soaked with putty, and finally the putty is cured at elevated temperature.
  • further high-temperature-resistant insulating mats can also be inserted between the individual layers of the winding.
  • a strip-shaped, 1 mm wide and 0.3 mm thick conductor pre-product made of a copper-tin matrix with 1159 embedded niobium filaments was assumed.
  • the preliminary conductor product was provided with a glass fiber covering on which an organic size was applied.
  • a water glass-talcum mixture with about 60% by weight of sparkling water glass and about 40% by weight of talc was used as the putty. If the water glass remains open for a long time before mixing with the talcum powder, it becomes thinner. It is then advisable to increase the proportion of talcum to increase the viscosity of the putty.
  • the bobbin used to wind the bobbin was made of non-magnetic stainless steel and was equipped with two disk-shaped side flanges and a central bore with a diameter of 25 mm.
  • the inner winding diameter was 30 mm, the outer winding diameter 50 mm, the winding length 40 mm.
  • the coil was then first heated to about 37 ° C. for a few hours to dry the putty. This is sufficient if the water vapor can escape from the winding, for example through holes provided in the disk-shaped side flanges or in other ways. This drying step prevents cracks from appearing in the putty during subsequent curing. A second heat treatment at about 117 ° C for several hours then gave the putty the required strength. After appropriate determination of the conductor ends for later assembly of the contacts, the coil was finally wrapped in a zirconium foil serving as getter and subjected to reaction annealing at about 700 ° C. under argon for about two days. After cooling, the coil was cast with casting resin in a protective trough. Instead of the casting resin, an inorganic putty can also be used.
  • the finished coil was then inserted into the bore of a larger superconducting magnet and tested in its magnetic field. With a magnetic induction of 7 Tesla generated by the outer coil, a magnetic induction of 9 Tesla was achieved in the bore of the inner coil.
  • the critical current density of the Nb 3 Sn conductor of the inner coil was approximately 90,000 A / cm 2 in an external field of 2 Tesla, and approximately 45,000 A / cm 2 in an external field of 7 Tesla .
  • the method according to the application has proven itself in the same way for larger coils of up to 177 mm winding length and 119 mm outer winding diameter.
  • the packing density of the winding could be increased even further by omitting the insulating mats between the individual winding layers. In this case, putty is applied to each winding layer and the next winding layer is wound directly over it. However, omitting the layer insulation is only recommended if the actual conductor insulation consists of a fiber wound. If the pre-products for insulation are only wrapped with glass fiber, for example, then the insulating mats should be retained to insulate the winding layers from each other.
  • the putty applied to the previous winding layer is not sufficient to impregnate the insulation mat, putty is expediently applied to it again before the next winding layer is applied.
  • organic binders for example with polyvinyl butyral
  • the carbon released during the thermal decomposition of the polyvinyl butyral during the heating of the winding for reaction annealing is prevented by the putty from forming conductive bridges between the turns. Carbon-releasing substances therefore do not need to be removed or at least not completely removed before the reaction annealing when winding the coil.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)

Claims (6)

1. Procédé pour fixer les enroulements d'une bodine magnétique supraconductrice, constituée à partir de semi-produits conducteurs et dans le cas duquel, les propriétés supraconductrices sont obtenues par un recuit réactionnel de l'enroulement terminé, procédé caractérisé en ce que, lors du bobinage des semi-produits conducteurs, un mastic en un matériau inorganique isolant, qui, après durcissement, résiste aux basses températures nécessaires pour amener l'état supraconducteur et aux températures élevées nécessaires pour le recuit réactionnel, est introduit dans l'enroulement et après l'achèvement de cet enroulement, est durci avant d'effectuer le recuit réac- tionnal.
2. Procédé selon la revendications 1, caractérisé en ce qu'un mélange de verre soluble et de talc est utilisé comme mastic.
3. Procédé selon la revendication 2, caractérisé en ce qu'un mélange d'environ 60% en poids de verre soluble et d'environ 40 % en poids de talc est utilisé.
4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que l'enroulement est soumis avant le recuit réactionnel, tout d'abord en vue du séchage du mastic, à un traitement thermique à une première température, puis pour le durcissement du mastic à un autre traitement thermique à une seconde température plus élevée.
5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que sur un corps de bobine résistant à des températures élevées, on rapporte tout d'abord un matelas isolant en un matériau resistant à des températures élevées qui est ensuite imprégné par le ciment, puis les couches successives de l'enroulement conducteur sont déposées et sont respectivement enduites du mastic et enfin, l'enroulement terminé est entouré avec un autre matelas isolant résistant à des températures élevées que l'on imprègene de mastic et - enfin le mastic est durci à haute température.
6. Procédé selon la revendication 5, caractérisé en ce que d'autres matelas isolants résistant à des températures élevées sont en plus insérés entre les différentes couches de l'enroulement.
EP81107230A 1980-09-27 1981-09-14 Procédé pour fixer les enroulements d'une bobine magnétique supraconductrice Expired EP0048880B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3036536 1980-09-27
DE19803036536 DE3036536A1 (de) 1980-09-27 1980-09-27 Verfahren zum fixieren der windungen einer supraleitenden magnetwicklung

Publications (2)

Publication Number Publication Date
EP0048880A1 EP0048880A1 (fr) 1982-04-07
EP0048880B1 true EP0048880B1 (fr) 1984-09-12

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP81107230A Expired EP0048880B1 (fr) 1980-09-27 1981-09-14 Procédé pour fixer les enroulements d'une bobine magnétique supraconductrice

Country Status (2)

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EP (1) EP0048880B1 (fr)
DE (2) DE3036536A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH678465A5 (fr) * 1988-07-14 1991-09-13 Asea Brown Boveri
US5140292A (en) * 1991-02-19 1992-08-18 Lucas Schaevitz Inc. Electrical coil with overlying vitrified glass winding and method

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE683279A (fr) * 1965-06-28 1966-12-01
US3733692A (en) * 1971-04-16 1973-05-22 Union Carbide Corp Method of fabricating a superconducting coils
DE2907083C2 (de) * 1979-02-23 1983-08-25 Siemens AG, 1000 Berlin und 8000 München Supraleitende Magnetwicklung mit mehrren Wicklungslagen

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Publication number Publication date
DE3036536A1 (de) 1982-05-13
DE3166043D1 (en) 1984-10-18
EP0048880A1 (fr) 1982-04-07

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