US3794593A - Method of electrophoretically covering helically wound heating wires with an insulating layer - Google Patents

Method of electrophoretically covering helically wound heating wires with an insulating layer Download PDF

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Publication number
US3794593A
US3794593A US00281345A US3794593DA US3794593A US 3794593 A US3794593 A US 3794593A US 00281345 A US00281345 A US 00281345A US 3794593D A US3794593D A US 3794593DA US 3794593 A US3794593 A US 3794593A
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US
United States
Prior art keywords
wire
insulating layer
helically wound
electrophoretically
covering
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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
US00281345A
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English (en)
Inventor
R Coenen
A Kuiper
M Collaris
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US Philips Corp
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US Philips Corp
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Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
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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
    • C25D13/12—Electrophoretic coating characterised by the process characterised by the article coated
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating

Definitions

  • the invention relates to a method of electrophoretically covering helically wound heating wires for indirectly heated cathodes with an insulating layer, in particular heating Wires which are bent in the form of a V once or several times or bifilar-wound wires.
  • the invention furthermore relates to a heating wire comprising an insulating layer provided according to said method.
  • Heating wires for indirectly heated cathodes are usually covered electrophoretically with an insulating layer so that the ends of the helically wound heating wire which is usually bent in the form of a V once or several times or is a bifilar-wound wire, remain free from insulating material.
  • the wire is usually connected to current supply wires by welding with the bare ends.
  • measures are taken to reduce the influence of the capillary action in the place of separation between covered and non-covered parts. This can be done in a simple manner by filling the spaces of the wound wire with a suitable liquid just prior to dipping the Wire in the electrophoresis bath. Since the capillary spaces are filled by the said liquid, no suspension of insulating material of the electrophoresis bath is drawnin any longer.
  • a dipping liquid is preferably used the same liquid as that in which the insulating material is suspended.
  • the wound wire may be dipped in the electrophoresis bath and the electrophoresis voltage be applied rapidly as soon as the wire is dipped to the correct depth.
  • the electric field which moves the insulating particles in the suspension to the wire in a direction normal to the wire then prevents the particles from being taken along with the capillary flow parallel to the axis of the wound wire.
  • the gaps between the turns of the wire rapidly slit up so that mainly only suspension liquid is drawn above the dipping level by 3,794,593 Patented Feb. 26, 1974 capillary action.
  • the wire may be kept at an anapheretic potential during dipping the wire in the suspension, after which the voltage is switched in the desired direction for cataphoresis after the wire has been dipped to the correct depth in the electrophoresis bath.
  • the insulating particles are repelled so that substantially only the liquid is drawn in the capillary spaces. Only then is the potential switched.
  • the invention enables the usual tolerances for the spot of the separation of .covered and uncovered parts to be reduced to A.
  • FIG. 1 shows diagrammatically an arrangement for carrying out the method according to the invention
  • FIGS. 2 and 3 show embodiments of heating wires covered by said method.
  • Reference numeral 1 in FIG. 1 denotes a shaped heating wire which is wound helically and bent to form a V.
  • the helically wound wire may also be bent back and be a bifilar-wound wire.
  • the wire 1 is clamped in a holder 2.
  • the part of the shaped wire 1 present between the tip of the V and the line AA is to be coated electrophoretically with insulating material. If, as usual, the wire 1 is dipped to the line AA in an electrophoresis bath 4 which is present in a container 3, the suspension 4 will creep up the helically wound wire to slightly above the line AA as a result of the capillary action and reach the ends 9 of the wire, which ends, however, have to remain bare. So during electrophoresis a small quantity of insulating particles will also deposit on the ends 9 which impedes the welding of said ends to current supply conductors.
  • a very suitable measure is that in which the heating wire 1 is dipped in a suitable liquid down to the holder 2, said liquid filling the capillary spaces. Right after this, the wire is dipped in the bath 4.
  • the suspension can now no longer creep up.
  • the dipping liquid is preferably the same liquid as that in which the insulating material of the suspension 4 is suspended.
  • the suspension 4 preferably consists of aluminium oxide powder which is suspended in methyl alcohol.
  • the liquid being not electrically conductive, covering of the filament is carried out in this case by cataphoresis, the negative terminal of the current source 5 being connectable to the holder 2 by means of a switch 6.
  • the container 3 is connected to a positive potential. It is possible to apply the negative potential to the holder 2 only after the heating wire 2 has been dipped in the suspension 4 down to the line AA. In that case a uniformly thick insulating layer 7 is obtained as is shown in FIG. 2. It is of advantage, however, to give the tip of the V a thickening 8 and to make the thickness of the remaining insulating layer 7 thin.
  • the thickening 8 serves to center the heating member in a cathode support, while the layer 7 does not contact the cathode support.
  • a thin layer 7 has the advantage of being slightly flexible so that the V- shaped parts can be squeezed a little when inserted into a cylindrical support of a cathode without the layer 7 chipping oflf.
  • the cataphoresis potential is already applied before the V-shaped helically the deposition of insulation material on the ends 9 can also be avoided by applying an anaphoretic potential at the wire 1 during the dipping of the wire 1 in the suspension 4.
  • the holder 2 with the Wire 1 is then made positive relative to the suspension 4.
  • the insulating particles from the suspension which are drawn in the wire turn 1 by capillary action are then repelled so that substantially only the suspension medium can reach the capillary spaces.
  • the switch 7 is switched so that the wire 1 becomes negative relative to the suspension 4- and insulating material deposits on the wire 1 down to the line AA.
  • a thickening 8 can be obtained in this case by keeping the tip of the shaped wire in the suspension for some time when the wire 1 is drawn out of the suspension.
  • a method of electrophoretically covering a helically wound heating wire for indirectly heated cathodes with an insulating layer to a given distance from the ends of the wire, which ends are clamped in a holder during covering comprising the steps of dipping the heating wire down to the desirable depth into the electrophoresis bath, applying an anaphoretic potential to the wire until the liquid in the capillary spaces has-reached its highest position, and thereafter, applying the electrophoresis potential.

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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)
  • Resistance Heating (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Branch Pipes, Bends, And The Like (AREA)
  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
US00281345A 1971-08-18 1972-08-17 Method of electrophoretically covering helically wound heating wires with an insulating layer Expired - Lifetime US3794593A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7111360A NL7111360A (ja) 1971-08-18 1971-08-18

Publications (1)

Publication Number Publication Date
US3794593A true US3794593A (en) 1974-02-26

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Family Applications (1)

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US00281345A Expired - Lifetime US3794593A (en) 1971-08-18 1972-08-17 Method of electrophoretically covering helically wound heating wires with an insulating layer

Country Status (7)

Country Link
US (1) US3794593A (ja)
JP (1) JPS5420827B2 (ja)
CA (1) CA977713A (ja)
DE (1) DE2237318C3 (ja)
FR (1) FR2149561B1 (ja)
GB (1) GB1360169A (ja)
NL (1) NL7111360A (ja)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050133372A1 (en) * 2001-11-30 2005-06-23 The University Of North Carolina Method and apparatus for attaching nanostructure-containing material onto a sharp tip of an object and related articles

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3630224C2 (de) * 1986-09-05 1994-01-05 Nokia Deutschland Gmbh Verfahren zur Herstellung von Oxidkathodendrähten durch kataphoretisches Beschichten
CN104008940B (zh) * 2014-04-28 2016-04-27 安徽华东光电技术研究所 一种x波段空间行波管阴极灯丝电泳方法

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050133372A1 (en) * 2001-11-30 2005-06-23 The University Of North Carolina Method and apparatus for attaching nanostructure-containing material onto a sharp tip of an object and related articles
US20080006534A1 (en) * 2001-11-30 2008-01-10 The University Of North Carolina At Chapel Hill Deposition method for nanostructure materials
US7887689B2 (en) * 2001-11-30 2011-02-15 The University Of North Carolina At Chapel Hill Method and apparatus for attaching nanostructure-containing material onto a sharp tip of an object and related articles
US8002958B2 (en) 2001-11-30 2011-08-23 University Of North Carolina At Chapel Hill Deposition method for nanostructure materials

Also Published As

Publication number Publication date
DE2237318C3 (de) 1979-04-05
JPS4830363A (ja) 1973-04-21
NL7111360A (ja) 1973-02-20
GB1360169A (en) 1974-07-17
DE2237318A1 (de) 1973-02-22
FR2149561A1 (ja) 1973-03-30
CA977713A (en) 1975-11-11
DE2237318B2 (de) 1978-08-03
JPS5420827B2 (ja) 1979-07-25
FR2149561B1 (ja) 1976-10-29

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