US3622483A - Electrical deposition of material - Google Patents

Electrical deposition of material Download PDF

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Publication number
US3622483A
US3622483A US774035A US3622483DA US3622483A US 3622483 A US3622483 A US 3622483A US 774035 A US774035 A US 774035A US 3622483D A US3622483D A US 3622483DA US 3622483 A US3622483 A US 3622483A
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US
United States
Prior art keywords
conductive film
particles
support
cathode
anode
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 - Lifetime
Application number
US774035A
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English (en)
Inventor
Robert Paul Randall
Henry Kenneth Beale
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.)
EMI Ltd
Electrical and Musical Industries Ltd
Original Assignee
EMI Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by EMI Ltd filed Critical EMI Ltd
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Publication of US3622483A publication Critical patent/US3622483A/en
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/22—Servicing or operating apparatus or multistep processes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/22—Applying luminescent coatings
    • H01J9/221—Applying luminescent coatings in continuous layers
    • H01J9/225—Applying luminescent coatings in continuous layers by electrostatic or electrophoretic processes

Definitions

  • This invention relates to the electrical deposition of insulating material and in particular to the deposition of a thin layer of particles onan insulating support.
  • One object of the present invention is to provide an improved method of depositing a thin layer of particles on an insulating support, with a view to reducing the limitation referred to in the preceding paragraph.
  • a method of depositing a thin layer of insulating particles on an insulating support which comprises the steps of providing a surface of the support with an electrically conductive film, positioning the support in an electrically conducting solution in which said particles are suspended so that the support is located between the two electrodes in said solution, and, without electrical connection being made to said conductive film, establishing a potential difference between said electrodes to cause said particles to be deposited on said conductive film.
  • the conductive film takes only the current needed to prevent the build up of electrostatic charges on the insulating support. Therefore, although the conductive film acts as an electrode in addition to the other two electrodes it need only be of the order of a few tens of angstroms thick.
  • the invention is thus especially suited to processes where it is desired to deposit insulating particles on a thin conducting film without damaging the film. Alternatively, should it be desired to remove the film after deposition of the particles, this is facilitated due to the thickness of the film.
  • the conductive film is preferably antimony and it can be substantially dispersed by washing in running water or by baking in air at about 400 C. or both.
  • FIG. of the accompanying drawing shows in diagrammatic form one stage in the method of producing a luminescent screen for an image intensifier.
  • Particles "of the phosphor to be deposited as the screen are put into suspension by adding 780 milligrams of the phosphor to 900 milliliters of isopropyl distilled alcohol.
  • the phosphor in this example is a fine grade zinc silver sulfide (ZnSAg).
  • ZnSAg fine grade zinc silver sulfide
  • the suspension is subjected to ultrasonic agitation for about minutes. During this period 21 milliliters of zirconium nitrate N/IOO solution are added.
  • the suspension is ready for use and it is put into a transport cell 1 which is illustrated diagrammatically in the drawing.
  • the insulating support 2 on which he phosphor particles are to be deposited is in the form of a fine glass or mica sheet mounted on an electrically conducting ring 3.
  • the support Before being placed in the cell 1, the support is provided, on that surface on which the particles are to be deposited with a conductive film 4 of antimony which extends over the edge of the ring 3 or is otherwise electrically connected to it.
  • the film of antimony is applied by evaporation of 20 milligrams of antimony from a tungsten spiral placed about 6 inches from the support.
  • the antimony film is only a few tens of angstroms thick and it causes a reduction of the light transmission of the support only by about l5 percent. 7
  • the support After the support has been provided with the conductive film of antimony, it is immersed in the suspension 7 in the transport cell 1, as indicated in the drawing, between an anode 5 and a cathode 6.
  • the electrodes 5 and 6 are about 4 to 5 centimeters apart and the insulating support 2 is about 3 to 4 centimeters from the anode 5 and is positioned so that the conductive film 4 faces the anode.
  • the anode and the cathode are connected to the respective terminals of a suitable source of potential, of say between 1000 and 200 volts.
  • the potential is arranged to produce a current through the liquid suspension 7 of about 14 m. With a current of this magnitude, a monolayer 8 of phosphor particles (that is a layer of single particle thickness) is deposited on the conductive film 4 in about 7 minutes.
  • the support 2 is removed from the transport cell and the support is rinsed for approximately 7 minutes in running demineralized water. This removes most of the antimony film.
  • the luminescent screen so formed is aluminized, and thereafter the nitrocellulose film deposited in known manner on the phosphor particles as a preliminary to aluminizing is removed by baking the screen at 400 C. in air about l0 minutes. This baking also serves to oxidize and/or remove residual antimony from beneath the phosphor particles, so that the final efiect of the antimony on the transparency of the support is slight. It will therefore be appreciated that the removal of rendering innocuous of the an timony film is achieved by steps which would be taken even if the phosphor layer has been settled by precipitation not utilizing the conductive film 4.
  • the suspension in the cell 1 may be used for settling a number of luminescent screens but it is preferable to subject the suspension to ultrasonic agitation for approximately 30 seconds before each subsequent settling process.
  • the layer of phosphor particles is a monolayer, screens of very fine texture are obtained, capable of producing images of high definition. After removal of the antimony the particles remain on the insulating support 2 as tightly packed adherent layer which can be removed only by relatively vigorous mechanical scraping.
  • the conductive film 4 is not subject to chemical attack during the settling process, extended settling periods or high currents, of about 50 m, can be used.
  • substantial electrodes 5 and 6 enables such high currents to be handled, and as a result the invention can be used for the deposition of phosphor particles of larger size, which would normally drop out of suspension in the time required for electrophoretic deposition using smaller currents.
  • the invention is not confined to the formation of luminescent screens such as used in image intensifiers, and it can be used for the formation of other screens and indeed for the deposition of insulating materials other than phosphor particles, for example, particles of magnetic material such as gamma ferric oxide.
  • the conductive film provided on the insulating support need not of antimony, and aluminum can be used as an alternative in the example described above. As the conductive film can be very thin, producing substantially little light attenuation its removal is not absolutely necessary, and any residue which is left after the normal processes of washing and baking can be allowed to remain.
  • a stainless steel stocking-stitch mesh may be inserted between the anode and the support 2 during the settling process, to counteract the turbulence in the vicinity of the electrode 5.
  • Other modifications may also be used in the process described.
  • an annulus of conductive material connected to the film 4 may be provided on the surface of the support 2 which faces the cathode 6.
  • a method of depositing a layer of insulating particles on an insulating support which comprises the steps of providing a surface of the support with an electrically conductive film, positioning the support in an electrically conducting solution in which said particles are suspended so that the support is located between two electrodes in said solution, and, without electrical connection being made to said conductive film, establishinga potential difference between said electrodes to cause said particles to be deposited on said conductive film, in which the support is positioned in said solution by mounting on an electrically conductive ring which is electrically connected to the film and in sight of both said electrodes but which is not electrically connected to said electrodes.
  • a method according to claim 1 in which said surface is washed alter deposition of the particles thereon so that the conductive film is at least partially removed.
  • a method of depositing a layer of insulating particles on an insulating support comprising the steps of providing a surface of the support with a thin electrically conductive film electrically connected to a further electrically conductive part which can be seen from the side of said support opposite said surface, positioning said support between an anode electrode and a cathode electrode in an electrically conducting solution containing said particles in suspension so that said conductive film faces anode and said further conductive part faces said cathode, and, without electrical connection being made to said conductive film or said further conductive part, establishing a potential difference between said two electrodes to cause said particles to be deposited on said conductive film.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Hybrid Cells (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US774035A 1967-11-08 1968-11-07 Electrical deposition of material Expired - Lifetime US3622483A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB50821/67A GB1247731A (en) 1967-11-08 1967-11-08 Improvements relating to the electrical deposition of material

Publications (1)

Publication Number Publication Date
US3622483A true US3622483A (en) 1971-11-23

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ID=10457512

Family Applications (1)

Application Number Title Priority Date Filing Date
US774035A Expired - Lifetime US3622483A (en) 1967-11-08 1968-11-07 Electrical deposition of material

Country Status (4)

Country Link
US (1) US3622483A (de)
DE (1) DE1807463A1 (de)
GB (1) GB1247731A (de)
NL (1) NL6815707A (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6722536B2 (en) 2002-05-13 2004-04-20 Smith Kline Beecham Corporation Nozzle for dispensing viscous material

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1590596A (en) * 1920-10-08 1926-06-29 Taylor Lab Inc Production of colloidal material
US1641322A (en) * 1921-10-15 1927-09-06 Czapek Emil Process for the production of filmlike bands from cellulose solutions and similar initial materials
US2898279A (en) * 1956-06-14 1959-08-04 Commw Of Australia Coating surfaces by employing an electrostatic field

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1590596A (en) * 1920-10-08 1926-06-29 Taylor Lab Inc Production of colloidal material
US1641322A (en) * 1921-10-15 1927-09-06 Czapek Emil Process for the production of filmlike bands from cellulose solutions and similar initial materials
US2898279A (en) * 1956-06-14 1959-08-04 Commw Of Australia Coating surfaces by employing an electrostatic field

Also Published As

Publication number Publication date
NL6815707A (de) 1969-05-12
DE1807463A1 (de) 1969-06-12
GB1247731A (en) 1971-09-29

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