US3533919A - Manufacture of superconductors - Google Patents

Manufacture of superconductors Download PDF

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US3533919A
US3533919A US779819A US77981968A US3533919A US 3533919 A US3533919 A US 3533919A US 779819 A US779819 A US 779819A US 77981968 A US77981968 A US 77981968A US 3533919 A US3533919 A US 3533919A
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United States
Prior art keywords
metal
tin
source
tape
niobium
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US779819A
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Prior Arthur Cunningham
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National Research Development Corp UK
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Nat Res Dev
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Priority claimed from GB7038/68A external-priority patent/GB1207593A/en
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/24—Vacuum evaporation
    • C23C14/32—Vacuum evaporation by explosion; by evaporation and subsequent ionisation of the vapours, e.g. ion-plating
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14—Metallic material, boron or silicon
    • C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/24—Vacuum evaporation
    • C23C14/28—Vacuum evaporation by wave energy or particle radiation
    • C23C14/30—Vacuum evaporation by wave energy or particle radiation by electron bombardment
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • C25D5/38—Pretreatment of metallic surfaces to be electroplated of refractory metals or nickel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/80—Material per se process of making same
    • Y10S505/815—Process of making per se
    • Y10S505/816—Sputtering, including coating, forming, or etching

Definitions

  • a process for depositing a first metal on a second metal which readily acquires a tenacious oxide film includes the steps of evaporating a layer of the first metal on a body of the second metal and electrodepositing a further quantity of the first metal on the resulting body.
  • the evaporation step may include exposing the second metal to particles of the first metal liberated by electron bombardment in vacuo.
  • the first metal may be mainly tin and the second metal mainly niobium.
  • the present invention relates to the deposition of one metal on another.
  • a well-known process for depositing a layer of one metal on another is electrodeposition, by which thick deposits can be built up fairly quickly.
  • this process is impracticable for some metals which have a tenacious oxide film, such as niobium.
  • a layer of tin applied to niobium by electroplating will not adhere to the niobium.
  • a process for depositing a first metal on a second metal which readily acquires a tenacious oxide film includes the steps of evaporating a layer of the first metal on a body of the second metal and electrodepositing a further quantity of the first metal on the resulting body.
  • the first metal may be mainly tin and the second metal mainly niobium.
  • a source 21, made of tungsten or molybdenum, and containing tin is connected via a tube 23 (made of molybdenum or titanium) to a reservoir 25 so that the source 21 may be continually replenished with liquid tin.
  • the source 21, the tube 23 and the reservoir 25 are all heated to keep the tin molten. This is shown schematically by a heater 27.
  • the source 21 is maintained at earth potential.
  • a circular filament 29 made of 0.015 inch tungsten or tantalum wire is used as an emitter of electrons to bombard the source 21.
  • a total current of some 20 amps AC. is caused to flow in the filament 29.
  • the filament 29 is supported within a hollow electrode 31 having the shape of the solid of revolution of a T about its vertical axis.
  • the electrode 31 is maintained at a negative potential of 4,500 volts, and the filament 29 is connected to it.
  • the whole assembly is held in an evacuated chamber or evacuated chambers. This is indicated schematically by an envelope 33.
  • the source 21 In operation at a low rate of evaporation the source 21 is heated principally by bombardment of electrons ejected from the filament 29. In operation at a high rate of evaporation, however, the source 21 is heated by bombardment of electrons ejected by the filament 29, and also by an electric discharge passing through the ionised tin vapour directly between the electrode 31 and the source 21. In action the tin particles evaporated from the source 21 pass against the electron stream through a hole 35 in the electrode 31.
  • the niobium tape is wound off a reel 37, over four sets of pulleys 3-9, 41, 43 and 45 and (after coating) on a reel 47.
  • the pulleys may be multiple so that the tape passes many times over the evaporation source in such a way that both sides of the tape are coated.
  • the tape In order to achieve a firmly adherent coating of tin it is necessary for the tape to be heated to some 400-SO0 C. either during or after coating. If the tape is passing slowly over the source it becomes heated sufficiently by radiation and electron bombardment from the filament but at a more rapid passage this heating is not sufficient. The heating can then be conveniently done in the coating apparatus by means of subsidiary electron bombardment heaters 49, 51 which heat the tape after deposition on each pass and before the deposit can be rubbed off by passage over a pulley.
  • a number of separate lengths of tape could be simultaneously passed over the source or over a pair of sources to coat both sides. Each tape would then pass more slowly over the source.
  • a very thin layer of tin deposited by the process described above is adequate to act as a key to enable a thicker deposit to be built up by electrodeposition, as for example from a potassium stannate bath. This deposit can be built up to the correct thickness for producing the desired quantities of niobium tin.
  • the process would work in the same way if the source 21 contained an alloy which was mainly tin. Similarly the tape could be an alloy which was mainly niobium. Furthermore the process may be applicable to the plating of other metals which readily acquire tenacious oxide films, for example, aluminum.
  • a method of depositing a first metal composed mainly of tin on a second metal composed mainly of niobium and which readily acquires a tenacious oxide film comprises the steps of: bombarding said first metal in liquid form with electrons from an electron emitter in vacuo to evaporate said first metal; contacting a body of said second metal with vapours of the evaporated first metal to form a vapour-deposited layer of said first metal on said body; a large voltage difference being maintained between said electron emitter and both said first metal and said body; and electrodepositing a further quantity of said first metal on the body over the vapour-deposited layer to provide an adherent electrodeposited layer of said first metal on said body.
  • a method according to claim 1 including the further step of heating the body provided with the electrodeposited layer at a temperature of at least 860 C.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Electrochemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Physical Vapour Deposition (AREA)

Description

Oct. 13, 1970 A. c. PRIOR MANUFACTURE 0F SUPERCONDUCTQRS Filed Nov. 29, 1968 I United States Patent ()flice 3,533,919 Patented Oct. 13, 1970 3,533,919 MANUFACTURE OF SUPERCONDUCTORS Arthur Cunningham Prior, Malvern, England, assignor to National Research Development Corporation, London, England Continuation-impart of application Ser. No. 434,924,
Feb. 24, 1965. This application Nov. 29, 1968, Ser.
Int. Cl. C23c 13/02; C2315 17/00 U.S. Cl. 204-38 Claims ABSTRACT OF THE DISCLOSURE A process for depositing a first metal on a second metal which readily acquires a tenacious oxide film includes the steps of evaporating a layer of the first metal on a body of the second metal and electrodepositing a further quantity of the first metal on the resulting body.
The evaporation step may include exposing the second metal to particles of the first metal liberated by electron bombardment in vacuo.
The first metal may be mainly tin and the second metal mainly niobium.
This application is a continuation-in-part of application Ser. No. 434,924, filed Feb. 24, 1965.
The present invention relates to the deposition of one metal on another.
A well-known process for depositing a layer of one metal on another is electrodeposition, by which thick deposits can be built up fairly quickly. However, this process is impracticable for some metals which have a tenacious oxide film, such as niobium. For example, a layer of tin applied to niobium by electroplating will not adhere to the niobium.
It is an object of the invention to provide a process for depositing a first metal on a second metal which has a tenacious oxide film whereby the deposit is more adherent.
According to the present invention a process for depositing a first metal on a second metal which readily acquires a tenacious oxide film includes the steps of evaporating a layer of the first metal on a body of the second metal and electrodepositing a further quantity of the first metal on the resulting body.
The first metal may be mainly tin and the second metal mainly niobium.
An embodiment of the invention will be described by. way of example with reference to the accompanying drawing, which is a diagram, partly in cross-section, of apparatus for tin plating niobium tape by vacuum evaporation of a tin source.
A source 21, made of tungsten or molybdenum, and containing tin is connected via a tube 23 (made of molybdenum or titanium) to a reservoir 25 so that the source 21 may be continually replenished with liquid tin. The source 21, the tube 23 and the reservoir 25 are all heated to keep the tin molten. This is shown schematically by a heater 27. The source 21 is maintained at earth potential.
A circular filament 29 made of 0.015 inch tungsten or tantalum wire is used as an emitter of electrons to bombard the source 21. A total current of some 20 amps AC. is caused to flow in the filament 29. The filament 29 is supported within a hollow electrode 31 having the shape of the solid of revolution of a T about its vertical axis. The electrode 31 is maintained at a negative potential of 4,500 volts, and the filament 29 is connected to it. The whole assembly is held in an evacuated chamber or evacuated chambers. This is indicated schematically by an envelope 33.
In operation at a low rate of evaporation the source 21 is heated principally by bombardment of electrons ejected from the filament 29. In operation at a high rate of evaporation, however, the source 21 is heated by bombardment of electrons ejected by the filament 29, and also by an electric discharge passing through the ionised tin vapour directly between the electrode 31 and the source 21. In action the tin particles evaporated from the source 21 pass against the electron stream through a hole 35 in the electrode 31.
The niobium tape is wound off a reel 37, over four sets of pulleys 3-9, 41, 43 and 45 and (after coating) on a reel 47. To increase the speed of coating the pulleys may be multiple so that the tape passes many times over the evaporation source in such a way that both sides of the tape are coated.
In order to achieve a firmly adherent coating of tin it is necessary for the tape to be heated to some 400-SO0 C. either during or after coating. If the tape is passing slowly over the source it becomes heated sufficiently by radiation and electron bombardment from the filament but at a more rapid passage this heating is not sufficient. The heating can then be conveniently done in the coating apparatus by means of subsidiary electron bombardment heaters 49, 51 which heat the tape after deposition on each pass and before the deposit can be rubbed off by passage over a pulley.
In an alternative arrangement for rapid coating of a large quantity of tape as an alternative to the large number of passes of a single tape a number of separate lengths of tape could be simultaneously passed over the source or over a pair of sources to coat both sides. Each tape would then pass more slowly over the source.
A very thin layer of tin deposited by the process described above is adequate to act as a key to enable a thicker deposit to be built up by electrodeposition, as for example from a potassium stannate bath. This deposit can be built up to the correct thickness for producing the desired quantities of niobium tin.
After electroplating it may be advantageous to heat the tape more rapidly to 860 C. or above in order to improve the quality of the deposit and its adhesion to the niobium.
Obviously the process would work in the same way if the source 21 contained an alloy which was mainly tin. Similarly the tape could be an alloy which was mainly niobium. Furthermore the process may be applicable to the plating of other metals which readily acquire tenacious oxide films, for example, aluminum.
I claim:
1. A method of depositing a first metal composed mainly of tin on a second metal composed mainly of niobium and which readily acquires a tenacious oxide film, which process comprises the steps of: bombarding said first metal in liquid form with electrons from an electron emitter in vacuo to evaporate said first metal; contacting a body of said second metal with vapours of the evaporated first metal to form a vapour-deposited layer of said first metal on said body; a large voltage difference being maintained between said electron emitter and both said first metal and said body; and electrodepositing a further quantity of said first metal on the body over the vapour-deposited layer to provide an adherent electrodeposited layer of said first metal on said body.
2. A method according to claim 1 wherein said body is unheated prior to contacting the vapours of the evaporated metal and is heated to a temperature of from 40 0500' C. after contacting said vapours.
3. A method according to claim 1 including the further step of heating the body provided with the electrodeposited layer at a temperature of at least 860 C.
4 4. A method according to claim 1 wherein said first 3,021,271 2/ 1962 Wehner 204192 inetal consists essentially of tin and said second metal 2,993,266 7/1961 Berry 2'9'25.42 consists essentially of niobium. 3,443,304 5/1969 Maier 29472.1 5. A method according to claim 4 wherein said first 3,346,467 10/1967 Allen 204-37 metal and said'body are electrically grounded.
- 5 HOWARD s. WILLIAMS, Primary Examiner References Cited R. L. ANDREWS, Assistant Examiner UNITED STATES PATENTS 3,305,473 2/1967 Moseson 204 29s 3,253,331 5/1966 'Limansky 29473.1 10 117 107;204 192 3,178,308 4/1965 Oxley et a1. 117-106
US779819A 1965-02-24 1968-11-29 Manufacture of superconductors Expired - Lifetime US3533919A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43492465A 1965-02-24 1965-02-24
GB7038/68A GB1207593A (en) 1968-02-13 1968-02-13 The deposition of one metal on another

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4043888A (en) * 1973-07-30 1977-08-23 Westinghouse Electric Corporation Superconductive thin films having transition temperature substantially above the bulk materials
US4081573A (en) * 1975-07-21 1978-03-28 Siemens Aktiengesellschaft Method for preparing superconductive Nb3 Sn layers on niobium surfaces for high-frequency applications
US4407871A (en) * 1980-03-25 1983-10-04 Ex-Cell-O Corporation Vacuum metallized dielectric substrates and method of making same
US4431711A (en) * 1980-03-25 1984-02-14 Ex-Cell-O Corporation Vacuum metallizing a dielectric substrate with indium and products thereof

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2993266A (en) * 1958-06-16 1961-07-25 Bell Telephone Labor Inc Method of making a capacitor employing film-forming metal electrode
US3021271A (en) * 1959-04-27 1962-02-13 Gen Mills Inc Growth of solid layers on substrates which are kept under ion bombardment before and during deposition
US3178308A (en) * 1960-09-07 1965-04-13 Pfaudler Permutit Inc Chemical vapor plating process
US3253331A (en) * 1962-12-06 1966-05-31 Westinghouse Electric Corp Glass-metallizing technique
US3305473A (en) * 1964-08-20 1967-02-21 Cons Vacuum Corp Triode sputtering apparatus for depositing uniform coatings
US3346467A (en) * 1964-05-01 1967-10-10 Nat Res Corp Method of making long length superconductors
US3443304A (en) * 1965-12-11 1969-05-13 Siemens Ag Method of producing superconductive tapes or bands

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2993266A (en) * 1958-06-16 1961-07-25 Bell Telephone Labor Inc Method of making a capacitor employing film-forming metal electrode
US3021271A (en) * 1959-04-27 1962-02-13 Gen Mills Inc Growth of solid layers on substrates which are kept under ion bombardment before and during deposition
US3178308A (en) * 1960-09-07 1965-04-13 Pfaudler Permutit Inc Chemical vapor plating process
US3253331A (en) * 1962-12-06 1966-05-31 Westinghouse Electric Corp Glass-metallizing technique
US3346467A (en) * 1964-05-01 1967-10-10 Nat Res Corp Method of making long length superconductors
US3305473A (en) * 1964-08-20 1967-02-21 Cons Vacuum Corp Triode sputtering apparatus for depositing uniform coatings
US3443304A (en) * 1965-12-11 1969-05-13 Siemens Ag Method of producing superconductive tapes or bands

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4043888A (en) * 1973-07-30 1977-08-23 Westinghouse Electric Corporation Superconductive thin films having transition temperature substantially above the bulk materials
US4081573A (en) * 1975-07-21 1978-03-28 Siemens Aktiengesellschaft Method for preparing superconductive Nb3 Sn layers on niobium surfaces for high-frequency applications
US4407871A (en) * 1980-03-25 1983-10-04 Ex-Cell-O Corporation Vacuum metallized dielectric substrates and method of making same
US4431711A (en) * 1980-03-25 1984-02-14 Ex-Cell-O Corporation Vacuum metallizing a dielectric substrate with indium and products thereof

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