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WO2003107720A1 - Ameliorations apportees a des articles recouverts d'un revetement, en particulier des articles en ceramique recouverts d'un revetement - Google Patents

Ameliorations apportees a des articles recouverts d'un revetement, en particulier des articles en ceramique recouverts d'un revetement Download PDF

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Publication number
WO2003107720A1
WO2003107720A1 PCT/GB2003/002556 GB0302556W WO03107720A1 WO 2003107720 A1 WO2003107720 A1 WO 2003107720A1 GB 0302556 W GB0302556 W GB 0302556W WO 03107720 A1 WO03107720 A1 WO 03107720A1
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WO
WIPO (PCT)
Prior art keywords
glass
electrode
conductor
coating
electrodes
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.)
Ceased
Application number
PCT/GB2003/002556
Other languages
English (en)
Inventor
Graham Ernist Brooks
Paul Mathew Williams
Richard Lloyd
Duncan Roy Coupland
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.)
Johnson Matthey PLC
Original Assignee
Johnson Matthey PLC
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 Johnson Matthey PLC filed Critical Johnson Matthey PLC
Publication of WO2003107720A1 publication Critical patent/WO2003107720A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • H05B3/02—Details
    • H05B3/03—Electrodes

Definitions

  • This invention concerns improvements in coated equipment, more especially it concerns coated ceramic articles for use in demanding environments such as in glass furnaces.
  • EP 559,330 We have previously described particularly effective platinum-coated articles in EP 559,330. These articles have been successfully introduced to the market as ACTTM articles, and have exhibited impressive lifetimes when exposed to the high temperature, corrosive, environment of glass furnaces.
  • EP 599,330 describes methods of forming such coated ceramic articles, and the welding of fabricated platinum group metal (“PGM”) products such as sheet, strip, tube etc. to the coating.
  • PGM platinum group metal
  • heating of the molten glass flowing in ceramic channels has been carried out by resistance heating of the glass between electrodes protruding through the wall of the channel into the mass of molten glass.
  • the electrodes commonly used are composed of tin oxide; the tin oxide is consumed, resulting in a certain level of contamination of the glass by tin oxide and the need to push new sections of electrode through the ceramic walls to give adequate heating. Additionally, the tin oxide electrodes require cooling to prevent overheating.
  • DE 100 05 821 Al describes an electrode for heating glass comprising a heat insulating refractory layer surrounded by a precious metal sleeve.
  • the centre of the electrode comprises a cooling system.
  • the heating current is supplied to the outer sleeve, which means that electrical contact must be maintained at the point where the electrode meets the surrounding furnace wall. This point is likely to become hot in use leading to the possibility that molten glass may leak from the furnace.
  • the electrodes are provided with a cooling system. A significant proportion of the energy supplied to the electrodes to heat the glass is thus removed by the cooling system. Process efficiency is thus compromised.
  • the present invention provides an electrode for heating glass, comprising an electrode matrix of refractory material, preferably of ceramic, said matrix having a glass contacting tip, a platinum or platinum alloy conductor, and a platinum or platinum alloy coating enveloping the tip of the matrix, said conductor and said coating being in electrical contact.
  • the conductor is welded to the coating.
  • the coating may be applied to the tip of the matrix using known techniques, preferably using flame spraying as described in EP 559,330, followed by shot peening. However, other methods may be used if desired, such as plasma spraying or chemical deposition.
  • the coating should be of such dimensions that it covers the entire ceramic that extends through the glass furnace wall into the glass furnace. Tests have shown that the electrode is highly resistant to attack by molten glass or the vapours in a glass furnace and unlike the known tin oxide electrodes, there is no need to feed the electrode through the wall.
  • the thickness of the coating is preferably at least 200 ⁇ m, and may be varied according to the current carrying requirements of the coating, for example up to 1200 ⁇ m or greater.
  • the thickness of the coating may vary across the tip of the matrix, or may be constant, and different thicknesses may be applied by flame spray coating, in manner known to the skilled person.
  • the coating must have adequate thickness to carry the designed current (with a safety margin) without exhibiting hot spots.
  • the platinum or platinum alloy conductor may be in the form of a round or square section bar or a tube. It must be of adequate thickness to carry the maximum designed current for the electrode, which may be 80 Amps or more. Whilst it is presently believed that is advantageous that the conductor is composed entirely of platinum or platinum alloy on the part of the electrode which is exposed to the highest temperatures, it is possible that alternative conductors may be developed. Because of the high intrinsic cost of the platinum in the conductor, a section of it exposed to lower temperatures may be replaced by a base metal, which is sufficiently refractory and conductive under the conditions. Nickel has found to be a suitable material for cooler sections.
  • the ceramic matrix may be any suitable sintered slip-cast or a molten-cast ceramic, and is suitably a mullite-based ceramic such as a zircon-mullite.
  • a preferred matrix component is a cylindrical shape having central bore suitable to carry the conductor.
  • an extended contact area contact between the conductor and the coating may be done by swaging the end of the conductor, in the manner of a rivet head, which is preferred in the case where the conductor is a rod, or welding a small plate onto the end of the conductor, which is preferred in the case where the conductor is a tube.
  • the conductor, or its extended area contact may be welded to the coating in any suitable manner, preferably by TIG welding.
  • Suitable platinum alloys for use in the present invention are 10%RhPt or 20%RhPt.
  • the electrode of the invention can incorporate, most readily where the conductor is in tube form, one or more thermocouples or thermisters which can provide detailed information on local temperatures in the glass furnace, and can permit much improved control of the temperature, and control of the total glass process.
  • the invention may also be expressed as a glass furnace having a plurality of electrodes of the invention.
  • the electrodes may be positioned in any suitable region of the furnace for example, in the floor or the sides of the glass channels, in the sides of the spout bowl or in the feeder channels.
  • the electrodes of the invention may be used at the front end of an electrically heated furnace, that is at the melter shelf itself.
  • the melter shelf uses consumable tin oxide electrodes which wear out quickly, and the furnace ceramic is eroded also. It is believed that the electrodes of the invention may offer particular advantage in this region of the furnace.
  • the invention further provides a method of operating a glass furnace, especially producing lead crystal, comprising providing electrical resistance heating through a plurality, at least a pair, of electrodes according to the invention.
  • Figure 1 is a schematic cross-section along an electrode according to the invention
  • Figure 2 is a schematic cross-section across a glass furnace spout bowl, incorporating two electrodes according to the invention, and;
  • Figure 3 is a schematic cross section along an electrode according to the invention inserted through the wall of a glass furnace.
  • a sintered zircon-mullite ceramic plug, 1 has a central bore of two different internal diameters, 2a, 2b.
  • the tip of the plug has a spray coating, 3, of
  • the coating thickness ranges from 200 ⁇ m on the walls to 1120 ⁇ m at the centre surrounding the bore 2a.
  • Fitted into bore 2a is a fabricated platinum tube, 4, having disc, 5, welded to its outer end.
  • the tube 4 has a threaded end, 6, into which is screwed a nickel rod, 7.
  • Rod 7 is a connectable to an electrical power supply by a connector, 8.
  • the coating 3 extends 40mm beyond the exposed end of the electrode when fitted through a hole into the glass channel or into a spout bowl.
  • the increase in coating thickness is intended to provide an even current density in use, avoiding hot spots.
  • the disc 5 is TIG welded onto the coating and provides good electrical connection.
  • the design may be adapted for other electrode positions such as the electrodes on a melter shelf.
  • a ceramic spout bowl, 10 has two opposing apertures, 11, through which are fitted two electrodes, 12, of similar construction to Fig 1.
  • the nickel bar has been replaced by a nickel tube, 14.
  • the spout bowl is filled, up to the level 15, with molten glass. Gobs of molten glass are withdrawn through a hole, 16, in the base of the bowl, using conventional technology such as a plunger (not shown). Electric power at 40v and 20-20A is provided to the electrodes, and this controls the temperature and viscosity of the glass at this final section of the furnace.
  • FIG. 3 An electrode 12 is shown fitted into the wall 17 of a glass furnace. In use, arrows 18 indicate radiation of heat into the glass melt 19. As the coating on the electrode does not extend to the junctions 20 between the electrode and the furnace wall, these points remain cool. Glass leakage is thus prevented without the need for the electrode to be cooled.
  • Electrodes of the present invention have been tested in a glass furnace for a period of 10 months at a voltage of 120V and a current of 25 A. As the electrodes do not need to be water-cooled, a decrease in heat loss of 30% was observed compared to standard electrodes. Start-up time was also improved, that is the time taken for the glass to move from a frozen to a flowing state. With electrodes of the present invention, start-up times of about 20 minutes were observed which can be compared to times of an hour or so with standard electrodes. The electrodes were also observed to provide accurate and fast responses, which is especially useful when heating coloured glass where heat radiation is low. The electrodes are also unaffected by the oxidation state of the glass, allowing them to be used in all types of glass.

Landscapes

  • Glass Melting And Manufacturing (AREA)
  • Resistance Heating (AREA)

Abstract

L'invention concerne un article recouvert d'un revêtement, tel qu'une électrode destinée à un four de verrerie. Cet article comprend une matrice (1) en céramique et un conducteur tubulaire (4) en platine. Ce conducteur est soudé à une plaque circulaire (5), qui est elle-même soudée à un revêtement de platine (3) sur la matrice. Les électrodes produites selon l'invention présentent une durée de vie prolongée comparé aux électrodes fusibles en oxyde d'étain et possèdent d'autres avantages sur le plan technique et en termes d'économie d'énergie.
PCT/GB2003/002556 2002-06-12 2003-06-12 Ameliorations apportees a des articles recouverts d'un revetement, en particulier des articles en ceramique recouverts d'un revetement Ceased WO2003107720A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0213402A GB0213402D0 (en) 2002-06-12 2002-06-12 Improvements in coated equipment
GB0213402.1 2002-06-12

Publications (1)

Publication Number Publication Date
WO2003107720A1 true WO2003107720A1 (fr) 2003-12-24

Family

ID=9938371

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2003/002556 Ceased WO2003107720A1 (fr) 2002-06-12 2003-06-12 Ameliorations apportees a des articles recouverts d'un revetement, en particulier des articles en ceramique recouverts d'un revetement

Country Status (2)

Country Link
GB (1) GB0213402D0 (fr)
WO (1) WO2003107720A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009128888A1 (fr) * 2008-04-14 2009-10-22 Hemlock Semiconductor Corporation Appareil de fabrication destiné à déposer un matériau et électrode utilisée dans un tel appareil
US8784565B2 (en) 2008-04-14 2014-07-22 Hemlock Semiconductor Corporation Manufacturing apparatus for depositing a material and an electrode for use therein

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1033847A (fr) * 1951-03-12 1953-07-16 Gen Electric Co Ltd électrode à immersion en fils métalliques
DE10005821A1 (de) * 2000-02-10 2001-08-23 Schott Glas Gekühlte Edelmetallelektrode zum Einstellen einer bestimmten Elektrodenoberfläche

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1033847A (fr) * 1951-03-12 1953-07-16 Gen Electric Co Ltd électrode à immersion en fils métalliques
DE10005821A1 (de) * 2000-02-10 2001-08-23 Schott Glas Gekühlte Edelmetallelektrode zum Einstellen einer bestimmten Elektrodenoberfläche

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009128888A1 (fr) * 2008-04-14 2009-10-22 Hemlock Semiconductor Corporation Appareil de fabrication destiné à déposer un matériau et électrode utilisée dans un tel appareil
CN102047751A (zh) * 2008-04-14 2011-05-04 赫姆洛克半导体公司 用于沉积材料的制造设备和其中使用的电极
JP2011523758A (ja) * 2008-04-14 2011-08-18 ヘムロック・セミコンダクター・コーポレーション 材料を蒸着するための製造装置及び当該装置において使用される電極
RU2494579C2 (ru) * 2008-04-14 2013-09-27 Хемлок Семикондактор Корпорейшн Производственная установка для осаждения материала и электрод для использования в ней
AU2009236679B2 (en) * 2008-04-14 2014-02-27 Hemlock Semiconductor Corporation Manufacturing apparatus for depositing a material and an electrode for use therein
US8784565B2 (en) 2008-04-14 2014-07-22 Hemlock Semiconductor Corporation Manufacturing apparatus for depositing a material and an electrode for use therein
US8951352B2 (en) 2008-04-14 2015-02-10 Hemlock Semiconductor Corporation Manufacturing apparatus for depositing a material and an electrode for use therein
TWI505743B (zh) * 2008-04-14 2015-10-21 Hemlock Semiconductor Corp 用於沉積一物質之製造設備及使用於其中之一電極

Also Published As

Publication number Publication date
GB0213402D0 (en) 2002-07-24

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