EP0142202B1 - Hochdruckgasentladungslampe - Google Patents

Hochdruckgasentladungslampe Download PDF

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Publication number
EP0142202B1
EP0142202B1 EP19840201589 EP84201589A EP0142202B1 EP 0142202 B1 EP0142202 B1 EP 0142202B1 EP 19840201589 EP19840201589 EP 19840201589 EP 84201589 A EP84201589 A EP 84201589A EP 0142202 B1 EP0142202 B1 EP 0142202B1
Authority
EP
European Patent Office
Prior art keywords
metal
granules
ceramic
volume fraction
lamp
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
EP19840201589
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English (en)
French (fr)
Other versions
EP0142202A1 (de
Inventor
Johannes Jacobus F. Geijtenbeek
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Gloeilampenfabrieken NV
Publication of EP0142202A1 publication Critical patent/EP0142202A1/de
Application granted granted Critical
Publication of EP0142202B1 publication Critical patent/EP0142202B1/de
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/36—Seals between parts of vessels; Seals for leading-in conductors; Leading-in conductors
    • H01J61/361—Seals between parts of vessel
    • H01J61/363—End-disc seals or plug seals

Definitions

  • the invention relates to a high-pressure gas discharge lamp provided with a translucent tubular ceramic lamp vessel which is sealed in a vacuum-tight manner, which accommodates a pair of electrodes and an ionizable gas filling and which is provided at its ends with current lead-in conductors each of which is connected to a respective electrode and to a respective external current conductor, at least one current lead-in conductor consisting of an electrically conducting sintered body which contains metal particles between ceramic granules.
  • a lamp is known from patent US-A-4,155,758.
  • Ceramic lamp vessels are used in lamp types in which during operation the lamp vessel is given a very high temperature, for example 900°C or higher.
  • high-pressure sodium discharge lamps and high-pressure mercury discharge lamps with halide additions are mentioned.
  • the term "ceramic lamp vessels" is to be understood to mean herein lamp vessels which comprise monocrystalline or polycrystalline material, such as, for example, translucent gas-tight aluminium oxide, magnesium aluminate, yttrium oxide, yttrium aluminium garnet and sapphire.
  • the polycrystalline material may contain one or more additions which influence the sintering process by which the lamp vessel is formed, for example in the case of aluminium oxide:magnesium oxide and/or yttrium oxide in a quantity of a few hundredths of a per cent.
  • a so-called cermet is used as current lead-in member.
  • the ceramic granules of the cermet may consist of the same or of a similar material as the lamp vessel.
  • the metal with its deviating coefficient of thermal expansion is present, dispersed between these granules, in a given volume fraction.
  • conducting cermets according to this Patent Specification as the dimensions of the ceramic granules are larger, the volume fraction of metal can be smaller. Nevertheless, at least 4.5% by volume of metal has to be present to obtain a conducting cermet even with the use of large granules (400-800 pm). In the said Specification it is therefore pointed out that fine ceramic particles have to be avoided in order to utilize the metal powder to the optimum.
  • the ceramic granules are coated with a uniform layer of metal powder.
  • the coating layers together constitute a separate continuous phase which has the form of a three-dimensional network of metal and in which the ceramic granules are dispersed as a discontinuous phase. If the ceramic granules are small or if fine particles are present between the ceramic granules, the same volume of ceramic material requires a larger quantity of metal powder to provide the ceramic grains with a uniform coating of metal powder.
  • the invention has for its object to provide a lamp of the kind described in the opening paragraph, in which the sinter body of the current lead-in conductor(s) has a high conductivity, even with the use of comparatively small granules and a small volume fraction of metal particles, and a great strength.
  • the sinter body of the current lead-in conductor contains ceramic granules, which are embedded in an electrically conducting mass of interweaving networks of ceramic material and metal respectively and in that the volume fraction of the metal particles in the electrically conducting mass, calculated at the theoretical densities of its pure constituents, lies between 15 and 60%.
  • the volume fraction of metal in the sinter body is small and much smaller than that of the conducting mass.
  • the sinter body consequently behaves in thermal respects (thermal conductivity and coefficient of thermal expansion) substantially like ceramic material, while it has in electrical respects the properties of metal.
  • the continuous conducting phase in the current lead-in conductors of the lamp according to the invention does not consist entirely nor substantially entirely of metal, but only for a given volume fraction.
  • This fraction generally lies between 15 and 60%, mostly between20 and 50%.
  • this conducting phase can be up to five to six times as voluminous as the quantity of metal incorporated therein, in this conducting phase, whilst maintaining a high conductivity, a larger volume of ceramic granules can be incorporated than when the conducting phase consists of the same quantity of unmixed metal, as is the case according to the said US Patent Specification.
  • the sinter body in the lamp according to the invention can contain a very small volume fraction of metal but nevertheless can have a very high conductivity.
  • the volume fraction of the metal in the continuous conducting phase is 30 ⁇ 5%.
  • the volume fraction of metal in the continuous conducting phase is so low that the volume of this phase is aboutthree to four times larger than the volume of the quantity of metal incorporated therein, and as a result a large volume of granules can be incorporated therein.
  • the volume fraction of metal in the continuous conducting phase is still so large that the sinter bodies obtained have a very low resistivity combined with a very low volume fraction of metal in these bodies.
  • volume fraction with respect to the sinter body of the lamp according to the invention is to be understood to mean: the ratio of the volume of a constituent, for example the metal, to the sum of the volumes of constituents, calculated at the theoretical densities of the pure constituents.
  • granules having dimensions between 50 to 500 pm are used.
  • the size of the granules in the lead-in conductor may cover this whole range or a sub-range therein, for example, the sub-range from 100 to 400 pm or the sub-range from 400 to 500 pm, or may have a very small spread and be, for example 200 ⁇ 20 ⁇ m.
  • the lower limit of the granule size is determined by practical possibilities to remove smaller granules during their manufacture and the upper limit is determined by the dimensions of current lead-in conductors.
  • the smallest dimension of such a conductor should be a few times, for example five times, larger than the dimension of the largest granule after sintering.
  • the volume fraction of granules in the sinter body may be very high and may amount to more than 95%.
  • the dimensions referred to are the dimensions of the granules used in the manufacture of sinter bodies. During sintering, about 40% of linear shrinkage occurs, as a result of which granules used have a size of, for example, 400-500 ⁇ m in diameter ultimately have a size of about 240 to about 300 pm.
  • the granules are coarse with respect to the metal powder from which the conducting network in the continuous phase of the sinter body is formed and are coarse with respect to the ceramic powder from which the ceramic network in the continuous phase of the sinter body is formed.
  • metal powder is used therein, whose particles have a size lying between 0.1 and 10 ⁇ m.
  • a powder is used having an average particle size lying between 0.4 and 1 ⁇ m.
  • Metals which are particularly suitable to be used are W, Mo, Fe, Ta and Nb, as well as combinations thereof.
  • Forthe ceramic network in the conducting phase use is advantageously made of powder having a specific surface area of about 6-30 m 2 /g and a particle size of mainly about 0.3 ⁇ m.
  • the sinter bodies of the current lead-in conductors may have a very low resistivity, which is measured in milliohm. cm, even with a very low volume fraction of metal of, for example, less than 1% by volume.
  • a directive for the smallest quantity of metal in sinter bodies required for electrical conductivity can be derived from Table 1.
  • This Table shows the relation between this smallest quantity of metal, the volume fraction of metal in the continuous phase and the average size of the granules when metal powder having a particle size of about 0.4 pm and a ceramic powder having a particle size of about 0.3 pm and a specific surface area of 30 m2/g are used.
  • granule size is the size of the granules before sintering, that is to say before about 40% of linear shrinkage due to sintering has occurred.
  • the sinter bodies generally contain more than the minimum required quantity of metal.
  • the difference in coefficient of expansion between the sinter body and the lamp vessel will also play an important part in choosing the volume fraction of metal in a sinter body. If the lamp vessel has a coefficient of expansion lying between that of the metal and that of the ceramic material of the sinter body, a large volume fraction of metal may be required to make the difference in coefficient of expansion between sinter body and lamp vessel very small.
  • the sinter body may be manufactured inter alia as follows. Ceramic powder is suspended in water. A substance may then be added, which influences the later sintering step, such as MgO. Instead, a magnesium salt, such as the nitrate, may be added. Expressed as MgO, the addition amounts, for example, to 0.03% by weight.
  • the suspension is dried and the cake thus obtained is broken.
  • the granulate is sieved to remove large lumps.
  • the granules are sieved to isolate the desired sieve fraction.
  • magnesium salts are converted into the oxide.
  • Metal powder, or instead thereof metal oxide powder, and ceramic powder are mixed in a predetermined volume ratio. This can be effected in a very suitable manner by suspending the powders in a liquid, such as ethanol, which does not or substantially not give rise to formation of lumps.
  • a substance influencing the sintering step such as MgO, may be added.
  • the suspension is dried.
  • the dry substance may be pulverized in a ball-mill.
  • metal oxide powder is used, the powder is reduced, for example in the case of tungsten oxide, in hydrogen at about 700°C. From the resulting powder mixture, the conducting mass of interlocking networks of ceramic material and of metal, respectively, is obtained after sintering.
  • the powder mixture is joined with the granules in a predetermined ratio and mixed therewith by rolling.
  • the mixture is compressed, for example isostatically, at a final pressure between 0.5 and 2 kbar.
  • the moulding obtained is sintered, for example after a mechanical pretreatment, in vacuo, in a neutral or in a reducing gas up to a temperature between about 1600 and 1800°C.
  • sinter bodies having a strength of considerably less than 250 MN/m 2 are not vacuum-tight or do not remain so.
  • the sinter bodies of the lamps according to the invention have a strength which is about 250 MN/m 2 or lies well over the said value and generally amounts to 300-400 MN/m 2 .
  • This great strength is due to the structure of the sinter bodies in which in fact the ceramic granules of the discontinuous phase are in contact with the ceramic network of the continuous phase.
  • numerous ceramic-ceramic bonds are obtained which anchor the continuous phase and the discontinuous phase to each other.
  • the aforementioned comparatively low temperature of between 1600 and 1800°C for sintering the current lead-in conductor is consequently amply sufficient to obtain a great strength and a high degree of vacuum-tightness, but is on the other hand sufficiently low to prevent a strong grain growth. Therefore, it is not necessary that metal powder is incorporated in the granules of the sinter body.
  • rupture surfaces of the sinter bodies according to the invention containing up to 35% by volume of metal in the continuous phase have shown that these rupture surfaces extend straight through granules. Apparently not the adhesion of the continuous phase to the granules, but the inner strength of the constituents of the sinter bodies is determinative of the strength of the sinter bodies. This is in contrast with the known sinter bodies, in which ceramic granules are incorporated in a continuous phase which is composed of metal powder. Cavities at one rupture surface then correspond to granules projecting from the other rupture surface. Apparently, in these known sinter bodies there is a low adhesion of the continuous phase to the granules. In sinter bodies according to the invention having in the continuous phase a metal content increasingly exceeding 35% by volume, rupture surfaces are found to extend increasingly along granule surfaces.
  • a transparent tubular ceramic lamp vessel 1 sealed in a vacuum-tight manner is arranged in an evacuated glass outer envelope 2 which is connected to a lamp cap 3.
  • Terminal wires 4 and 5, which are electrically connected to the lamp cap 3, carry the lamp vessel 1.
  • the terminal wire 5 is secured as an external conductor to a sleeve 6 of niobium, which acts as one of the current lead-in conductors, while the terminal wire 4 is connected to an external current conductor 8 which is connected to a sinter body 7 as current lead-in conductor.
  • the current lead-in conductors 6 and 7 both carry a respective electrode located in the lamp vessel 1 and are therefore not visible.
  • the lamp vessel has an ionizable gas filling consisting of 0.4 mgof indium, 17.5 mg of mercury, 3.7 mg of thallium iodide, 30 mg of sodium iodide, 2 mg of mercury iodide and argon at a pressure at room temperature of 5330 Pa.
  • the lamp vessel 1 has at its end a ceramic disk 10, which is fixed in the lamp vessel by sintering.
  • a sinter body 7 is connected in a vacuum-tight manner to the disk 10 by means of fusion joint material 13.
  • a tungsten electrode 11, 12 and an external molybdenum current conductor 8 are fixed in this body 7 and electrically connected to each other by means of the sinter body 7.
  • the lamp of Figures 1 and 2 can be operated vertically with the lamp cap 3 directed downwards.
  • Examples of sinter bodies (7) are characterized in Table 2 by their properties.
  • the sinter bodies were manufactured as follows: AI 2 0 3 powder having a specific surface area of 25 m 2 / g was suspended in water to which Mg(N0 3 ) 2 was added in a quantity corresponding to 250 ppm of MgO calculated with respect to AI 2 0 3 . The suspension was dried. The residue was broken and sieved through a sieve of 500 ⁇ m. The granulate was rolled in a ball-mill without balls and was then sieved to isolate the fraction stated in Table 1. The granules of this fraction were heated in air for 10 hours at 600°C and for 1 hour at 1200°C. These granules serve for the discontinuous phase of the sinter bodies.
  • Tungsten powder having a particle size of mainly 0.4 ⁇ m was suspended in ethanol and mixed with AI 2 0 3 powder of the said kind (containing 259 ppm of MgO) in a volume ratio yielding the metal fraction from column 3 of Table 1.
  • the suspension was dried; the residue was pulverized in a ball-mill. This powder serves for the continuous conducting phase from interlocking networks of the relevant sinter bodies.
  • the powder mixture and the granules were joined in such a ratio that the volume fraction of tungsten of column 2 of Table 1 is obtained therefrom.
  • the powder mixture and the granules were mixed by rolling.
  • the mixture was pressed isostatically at a final pressure of 1.6 kbar.
  • the moulding obtained was treated mechanically to give it the correct shape and was provided with a current conductor and an electrode.
  • the whole was sintered for 2 hours at 1700°C.

Landscapes

  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Claims (3)

1. Hochdruckgasentladungslampe mit einem durchscheinenden röhrenförmigen keramischen Lampenkolben, der vakuumdicht abgeschlossen ist, und in dem ein Elektrodenpaar und eine ionisierbare Gasfüllung angeordnet sind, und der an seinem Ende mit Stromzuführungsleitern versehen ist, die mit je einer betreffenden Elektrode und mit einem betreffenden externen Stromleiter verbunden sind, wobei wenigstens ein Stromzuführungsleiter aus einem elektrisch leitenden gesinterten Körper besteht, der Metallpartikeln zwischen keramischen Körnern enthält, dadurch gekennzeichnet, dass die keramischen Körner in eine elektrisch leitende Masse eingebettet sind, die aus ineinander greifende Netzwerke aus keramischem Material bzw. aus Metallpartikeln besteht, und dass der Volumenteil der Metallpartikeln in der elektrisch leitenden Masse, berechnet bei den theoretischen Dichten der reinen Bestandteile, zwischen 15 und 60% liegt.
2. Hochdruckgasentladungslampe nach Anspruch 1, dadurch gekennzeichnet, dass der Volumenteil zwischen 20 und 50% liegt.
3. Hochdruckgasentladungslampe nach Anspruch 2, dadurch gekennzeichnet, dass der Volumenteil zwischen 25 und 35% liegt.
EP19840201589 1983-11-10 1984-11-05 Hochdruckgasentladungslampe Expired EP0142202B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8303858 1983-11-10
NL8303858A NL8303858A (nl) 1983-11-10 1983-11-10 Hogedruk-gasontladingslamp.

Publications (2)

Publication Number Publication Date
EP0142202A1 EP0142202A1 (de) 1985-05-22
EP0142202B1 true EP0142202B1 (de) 1988-06-01

Family

ID=19842693

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19840201589 Expired EP0142202B1 (de) 1983-11-10 1984-11-05 Hochdruckgasentladungslampe

Country Status (5)

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EP (1) EP0142202B1 (de)
JP (1) JPH069135B2 (de)
DE (1) DE3471822D1 (de)
HU (1) HU189436B (de)
NL (1) NL8303858A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10030808B4 (de) * 1999-06-25 2006-03-23 Koito Mfg. Co., Ltd. Bogenentladungsröhre und Verfahren zu ihrer Herstellung

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0401403B1 (de) * 1989-06-06 1994-05-04 Heimann Optoelectronics GmbH Blitzlampe
GB2245557A (en) * 1990-06-27 1992-01-08 Johnson Matthey Plc Metal-ceramic composites
US5404078A (en) * 1991-08-20 1995-04-04 Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen Mbh High-pressure discharge lamp and method of manufacture
US5374872A (en) * 1992-11-13 1994-12-20 General Electric Company Means for supporting and sealing the lead structure of a lamp and method for making such lamp
DE4242123A1 (de) * 1992-12-14 1994-06-16 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Hochdruckentladungslampe mit einem keramischen Entladungsgefäß
US6126889A (en) * 1998-02-11 2000-10-03 General Electric Company Process of preparing monolithic seal for sapphire CMH lamp
JP3528649B2 (ja) * 1998-03-09 2004-05-17 ウシオ電機株式会社 ランプ用サーメットおよびセラミック製放電ランプ

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1571084A (en) * 1975-12-09 1980-07-09 Thorn Electrical Ind Ltd Electric lamps and components and materials therefor
DE3063533D1 (en) * 1979-11-12 1983-07-07 Emi Plc Thorn An electrically conducting cermet, its production and use

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10030808B4 (de) * 1999-06-25 2006-03-23 Koito Mfg. Co., Ltd. Bogenentladungsröhre und Verfahren zu ihrer Herstellung

Also Published As

Publication number Publication date
DE3471822D1 (en) 1988-07-07
HU189436B (en) 1986-07-28
JPH069135B2 (ja) 1994-02-02
HUT35877A (en) 1985-07-29
JPS60119068A (ja) 1985-06-26
EP0142202A1 (de) 1985-05-22
NL8303858A (nl) 1985-06-03

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