GB2032173A - Electric Incandescent Lamps - Google Patents
Electric Incandescent Lamps Download PDFInfo
- Publication number
- GB2032173A GB2032173A GB7933570A GB7933570A GB2032173A GB 2032173 A GB2032173 A GB 2032173A GB 7933570 A GB7933570 A GB 7933570A GB 7933570 A GB7933570 A GB 7933570A GB 2032173 A GB2032173 A GB 2032173A
- Authority
- GB
- United Kingdom
- Prior art keywords
- filament
- lamp
- lamp according
- coating material
- refractory metal
- 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.)
- Granted
Links
- 239000000463 material Substances 0.000 claims abstract description 25
- 239000011248 coating agent Substances 0.000 claims abstract description 23
- 238000000576 coating method Methods 0.000 claims abstract description 23
- 239000000203 mixture Substances 0.000 claims abstract description 19
- 239000003870 refractory metal Substances 0.000 claims abstract description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 13
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 13
- 229910052751 metal Inorganic materials 0.000 claims abstract description 9
- 239000002184 metal Substances 0.000 claims abstract description 9
- 229910052582 BN Inorganic materials 0.000 claims abstract description 6
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000002344 surface layer Substances 0.000 claims abstract description 6
- 229910003468 tantalcarbide Inorganic materials 0.000 claims abstract description 6
- 239000007788 liquid Substances 0.000 claims abstract description 5
- NFFIWVVINABMKP-UHFFFAOYSA-N methylidynetantalum Chemical compound [Ta]#C NFFIWVVINABMKP-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000011195 cermet Substances 0.000 claims abstract description 4
- 150000004767 nitrides Chemical class 0.000 claims abstract description 4
- 150000001247 metal acetylides Chemical class 0.000 claims abstract description 3
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 3
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 3
- 229910021332 silicide Inorganic materials 0.000 claims abstract description 3
- ZCUFMDLYAMJYST-UHFFFAOYSA-N thorium dioxide Chemical compound O=[Th]=O ZCUFMDLYAMJYST-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000010410 layer Substances 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 8
- 230000001464 adherent effect Effects 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 4
- 239000011214 refractory ceramic Substances 0.000 claims description 3
- 229910000449 hafnium oxide Inorganic materials 0.000 claims 1
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 claims 1
- 150000002736 metal compounds Chemical class 0.000 claims 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims 1
- 229910003452 thorium oxide Inorganic materials 0.000 claims 1
- 229910001928 zirconium oxide Inorganic materials 0.000 claims 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 abstract description 11
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 abstract description 10
- 229910052715 tantalum Inorganic materials 0.000 abstract description 9
- 230000008020 evaporation Effects 0.000 abstract description 8
- 238000001704 evaporation Methods 0.000 abstract description 8
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052721 tungsten Inorganic materials 0.000 abstract description 8
- 239000010937 tungsten Substances 0.000 abstract description 8
- 241000588731 Hafnia Species 0.000 abstract description 2
- CJNBYAVZURUTKZ-UHFFFAOYSA-N hafnium(IV) oxide Inorganic materials O=[Hf]=O CJNBYAVZURUTKZ-UHFFFAOYSA-N 0.000 abstract description 2
- 239000000919 ceramic Substances 0.000 abstract 1
- 239000011541 reaction mixture Substances 0.000 abstract 1
- 239000000725 suspension Substances 0.000 abstract 1
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 230000008021 deposition Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 229910010293 ceramic material Inorganic materials 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- CMOAHYOGLLEOGO-UHFFFAOYSA-N oxozirconium;dihydrochloride Chemical compound Cl.Cl.[Zr]=O CMOAHYOGLLEOGO-UHFFFAOYSA-N 0.000 description 2
- 229910004448 Ta2C Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000008246 gaseous mixture Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- MISXNQITXACHNJ-UHFFFAOYSA-I tantalum(5+);pentaiodide Chemical compound [I-].[I-].[I-].[I-].[I-].[Ta+5] MISXNQITXACHNJ-UHFFFAOYSA-I 0.000 description 1
- OEIMLTQPLAGXMX-UHFFFAOYSA-I tantalum(v) chloride Chemical compound Cl[Ta](Cl)(Cl)(Cl)Cl OEIMLTQPLAGXMX-UHFFFAOYSA-I 0.000 description 1
- FAQYAMRNWDIXMY-UHFFFAOYSA-N trichloroborane Chemical compound ClB(Cl)Cl FAQYAMRNWDIXMY-UHFFFAOYSA-N 0.000 description 1
- HHIQWSQEUZDONT-UHFFFAOYSA-N tungsten Chemical compound [W].[W].[W] HHIQWSQEUZDONT-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01K—ELECTRIC INCANDESCENT LAMPS
- H01K1/00—Details
- H01K1/02—Incandescent bodies
- H01K1/04—Incandescent bodies characterised by the material thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01K—ELECTRIC INCANDESCENT LAMPS
- H01K3/00—Apparatus or processes adapted to the manufacture, installing, removal, or maintenance of incandescent lamps or parts thereof
- H01K3/02—Manufacture of incandescent bodies
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Resistance Heating (AREA)
Abstract
To prevent or reduce blackening of the envelope due to evaporation of metal or carbon from the filament of an incandescent lamp, the filament is coated with a refractory, ceramic or cermet material which is stable at all temperatures at least up to the temperature attained by the filament in operation of the lamp. Suitable coating materials include refractory metal oxides such as zirconia, hafnia and thoria, refractory metal carbides, nitrides, borides and silicides, for example tantalum carbide and boron nitride, and mixtures of these materials with refractory metals which will not evaporate at the operating temperature. The coating may be deposited from suspension in a liquid, or from a vapour phase reaction mixture, or may be formed, for example, by carburisation of the surface layers of a tungsten or tantalum filament.
Description
SPECIF-iCATION Electric Incandescent Lamps
This invention relates to electric incandescent lamps of the type comprising a filament formed of refractory metal or carbon enclosed within a glass envelope, and to methods of manufacturing such lamps.
It is well known that, in an incandescent lamp having a refractory metal or carbon filament, blackening of the lamp envelope tends to occur as a result of evaporation of material from the filament at the high temperature attained by the filament in operation of the lamp, and deposition of the vaporised material on the envelope wall.
Tungsten, which is the metal most usually employed for forming lamp filaments, is particularly liable to undergo some evaporation under the conditions of operation of an incandescent lamp. In order to suppress this evaporation, it is customary to provide a gas filling within the envelope; however, this has the disadvantage, as compared with an evacuated envelope, that thermal loss from the filament occurs as a result of heat conduction in the gas.
The proportion of heat lost from the filament in this way may be up to at least 12.5%: such heat loss will of course result in an appreciable reduction in the brightness of the light emitted by the lamp, for a given power input.
It is an object of the present invention to provide incandescent lamps incorporating improved filaments whereby the above-described disadvantages can be reduced or overcome.
According to the invention, in an electric incandescent lamp consisting essentially of a filament enclosed within a glass envelope, the filament is composed of refractory metal or carbon with a continuous, adherent surface coating consisting of a refractory ceramic or cermet material which is stable at all temperatures at least up to the temperature attained by the filament in operation of the lamp, or of a mixture of two or more such materials.
The filament may be of a standard form, consisting either Of a carbon fibre or of a single, double or triple coil of fine wire composed of tungsten or of any other suitable refractory metal, for example tantalum, or refractory metal alloy.
The coating may consist of any ceramic material, or mixed metal-ceramic material, which is stable, that is to say does not undergo any decomposition, fusion or evaporation, at temperatures up to at least 24000C. Suitable coating materials include refractory metal oxides such as zirconia, hafnia and thoria, refractory metal carbides, nitrides, borides and silicides, especially tantalum carbide or boron nitride, and mixtures of these materials with refractory metals which will not evaporate at the aforesaid temperatures.
In the manufacture of the lamp, the refractory coating material may be deposited on the preformed filament from the liquid or vapour phase, the filament then being heated to cause the deposited material to form a homogeneous, adherent film covering the whole of thesurface of the filament. If desired a plurality of layers of different compositions may be applied to the filament in this manner. Alternatively, a metal filament may be heated in a gaseous atmosphere which will react with the surface layers of the filament metal to form a layer of the coating material, for example the metal carbide or nitride; if desired, the composition of the coating may be varied through its thickness, by varying the composition of a gaseous mixture from which it is formed, so as to form a plurality of layers of graded composition.In another alternative method of manufacture, a carbon filament may be coated with a refractory metal and heated to cause the metal to combine with the underlying carbon to form a carbide.
The refractory ceramic or cermet coating on the filament is effective in suppressing evaporation of the filament material during operation of the lamp. Thus the presence of this coating ensures that no blackening of the lamp envelope, due to evaporation of filament material, will occur, and furthermore renders unnecessary the use of a gas filling for suppressing evaporation from the filament. The envelope may therefore be evacuated, thus preventing thermal loss from the filament in operation.
Some specific filaments for lamps in accordance with the invention, and methods of manufacturing the filaments, will now be described in the following examples.
Example 1
The filament of this example is composed of tungsten wire coated with zirconia. A tungsten filament of standard design, for example a coiled coil filament, is liquid coated by immersion in a solution of zirconium oxychloride in methanol, the methanol is then evaporated off by heating the filament at 1 000C in vacuum and finally the filament is heated to a temperature of 6000C to decompose the zirconium oxychloride to zirconia and to form a film of deposited zirconia, of substantially uniform thickness of approximately one micron or more, over the whole of the surface of the filament.
Example 2
In this case a tungsten filament, suitably of coiled coil form, is provided with a coating of boron nitride. The preformed filament is heated to a temperature of 7500C while exposed to a flowing vapour mixture of boron trichloride with an excess of ammonia at a total vapour pressure of 100 to 200 N/m2. The vapours react to form boron nitride, which is deposited on the filament, and the heating of the filament is continued to form a homogenous film of boron nitride of thickness exceeding one micron over the whole of the surface of the wire.
Example 3
The filament of this example consists of tungsten or tantalum wire with a coating of tantalum carbide. The coating is formed on a tantalum filament by carburising the surface layers of the wire: the preformed filament, which may be of standard coiled form, is heated to 25000C while exposed to a flowing mixture of hydrogen and benzene containing more than 50% by volume of hydrogen. In the case of a tungsten filament, a thin layer of tantalum is deposited over the surface of the filament by the Van Arkel process, that is to say by decomposing tantalum iodide or tantalum chloride vapour at a temperature of 1700--18000C, and this layer is then carburised as in the case of a tantalum filament.If desired, the carbide surface layers may be of graded composition, the innermost layer or layers adjacent to the metallic tantalum or tungsten being composed of Ta2C and the outer layer or layers or TaC, possibly with an intermediate layer or layers of intermediate composition: this grading is achieved by varying the composition of the hydrogen-benzene mixture, the proportion of benzene being progressively increased as the carburisation proceeds.
Example 4
In this example a carbon filament is provided with a coating of tantalum carbide by deposition
of a layer of tantalum metal on the carbon filament by the vapour deposition process
described in Example 3, and carburisation of the
tantalum by combination with the carbon in the
surface layers of the filament. Carburisation may
occur during the deposition of the tantalum, or
may be promoted by heating the tantalum-coated
filament to 20000C in an inert atmosphere.
The manufacture of a lamp, incorporating a
filament produced in accordance with any of the
above examples, is completed by conventional
procedures, the filament being supported by wires
sealed into a pinched foot tube which is itself
sealed into an aperture in the glass envelope, and
the envelope being provided with a cap carrying
contacts to which the filament support wires are
connected.
Claims (14)
1. An electric incandescent lamp consisting
essentially of a filament enclosed within a glass
envelope, wherein the filament is composed of
refractory metal or carbon with a continuous,
adherent surface coating consisting of a refractory
ceramic or cermet material which is stable at all
temperatures at least up to the temperature
attained by the filament in operation of the lamp,
or of a mixture of two or more such materials.
2. A lamp according to Claim 1, wherein the said coating material consists of or includes one or more refractory metal oxides.
3. A lamp according to Claim 2, wherein the said coating material consists of or includes zirconium oxide, or hafnium oxide, or thorium oxide.
4. A lamp according to Claim 1, wherein the said coating material consists of or includes one or more of the refractory metal compounds consisting of carbides, nitrides, borides and silicides.
5. A lamp according to Claim 4, wherein the said coating material consists of or includes tantalum carbide or boron nitride.
6. A lamp according to Claim 1, wherein the said coating material consists of a mixture of one or more of the materials specified in Claim 2, 3, 4 or 5 with at least one refractory metal which will not evaporate at the said temperatures.
7. A lamp according to any preceding Claim, which lamp is evacuated.
8. A method of manufacturing a lamp according to any preceding Claim, wherein the said coating material is deposited on a preformed filament from the liquid or vapour phase, and the filament is then heated to cause the deposited material to form a homogeneous, adherent film covering the whole of the surface of the filament.
9. A method according to Claim 8, wherein a plurality of layers of different compositions are applied to the filament from the liquid or vapour phase.
10. A method of manufacturing a lamp according to any of the preceding Claims 1 to 7, which lamp has a metal filament, wherein the filament is heated in a gaseous atmosphere which will react with the surface layers of the filament metal to form a layer of said coating material.
1 A method according to Claim 10, wherein the composition of the said coating is varied through its thickness, by varying the composition of the gaseous atmosphere so as to form a plurality of layers of graded composition.
12. A method of manufacturing a lamp according to Claim 1, which lamp has a carbon filament, wherein the filament is coated with a refractory metal and is heated to cause the metal to combine with the underlying carbon to form a carbide.
13. A method of manufacturing a lamp according to Claim 1, substantially as hereinbefore described in any one of the specific
Examples 1,2,3 or 4.
14. An electric incandescent lamp manufactured by a method according to Claim 13.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7840035 | 1978-10-10 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2032173A true GB2032173A (en) | 1980-04-30 |
| GB2032173B GB2032173B (en) | 1982-11-24 |
Family
ID=10500236
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7933570A Expired GB2032173B (en) | 1978-10-10 | 1979-09-27 | Electric incandescent lamps |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2032173B (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3226012A1 (en) * | 1982-07-12 | 1984-01-12 | Naučno-issledovatel'skij i eksperimental'nyj institut avtomobil'nogo elektrooborudovanija i avtopriborov, Moskva | Process for producing incandescent lamps |
| WO2004021451A3 (en) * | 2002-08-30 | 2004-08-12 | Fraunhofer Ges Forschung | High-temperature stable metal emitter and method for the production thereof |
| WO2004079773A3 (en) * | 2003-03-06 | 2005-01-13 | Fiat Ricerche | High efficiency emitter for incandescent light sources |
| DE102004040711A1 (en) * | 2004-08-23 | 2006-03-02 | Schneider, Frank | Illumination element consists of a metal conductor which can be connected to a current source and which lights up on switching on the current and is completely covered by a ceramic coating providing thermal luminescence |
| DE102005006190A1 (en) * | 2005-02-10 | 2006-08-24 | Siemens Ag | Optical radiation device with radiation source providing radiation in visible wavelength region and non-visible heat radiation, used in illumination industry has metal oxide reflector giving radiation closer to black body radiation |
| US8278823B2 (en) | 2007-03-30 | 2012-10-02 | General Electric Company | Thermo-optically functional compositions, systems and methods of making |
| JP2014063666A (en) * | 2012-09-21 | 2014-04-10 | Stanley Electric Co Ltd | Incandescent lamp, process of manufacturing the same, and filament |
| US9252006B2 (en) | 2011-10-27 | 2016-02-02 | Stanley Electric Co., Ltd. | Incandescent bulb, filament, and method for manufacturing filament |
-
1979
- 1979-09-27 GB GB7933570A patent/GB2032173B/en not_active Expired
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3226012A1 (en) * | 1982-07-12 | 1984-01-12 | Naučno-issledovatel'skij i eksperimental'nyj institut avtomobil'nogo elektrooborudovanija i avtopriborov, Moskva | Process for producing incandescent lamps |
| WO2004021451A3 (en) * | 2002-08-30 | 2004-08-12 | Fraunhofer Ges Forschung | High-temperature stable metal emitter and method for the production thereof |
| WO2004079773A3 (en) * | 2003-03-06 | 2005-01-13 | Fiat Ricerche | High efficiency emitter for incandescent light sources |
| US7800290B2 (en) | 2003-03-06 | 2010-09-21 | C.R.F. Società Consortile Per Azioni | High efficiency emitter for incandescent light sources |
| DE102004040711A1 (en) * | 2004-08-23 | 2006-03-02 | Schneider, Frank | Illumination element consists of a metal conductor which can be connected to a current source and which lights up on switching on the current and is completely covered by a ceramic coating providing thermal luminescence |
| DE102005006190A1 (en) * | 2005-02-10 | 2006-08-24 | Siemens Ag | Optical radiation device with radiation source providing radiation in visible wavelength region and non-visible heat radiation, used in illumination industry has metal oxide reflector giving radiation closer to black body radiation |
| US8278823B2 (en) | 2007-03-30 | 2012-10-02 | General Electric Company | Thermo-optically functional compositions, systems and methods of making |
| US9252006B2 (en) | 2011-10-27 | 2016-02-02 | Stanley Electric Co., Ltd. | Incandescent bulb, filament, and method for manufacturing filament |
| JP2014063666A (en) * | 2012-09-21 | 2014-04-10 | Stanley Electric Co Ltd | Incandescent lamp, process of manufacturing the same, and filament |
| EP2711970A3 (en) * | 2012-09-21 | 2014-08-06 | Stanley Electric Co., Ltd. | Light source device, method for manufacturing the same and filament |
| US9252007B2 (en) | 2012-09-21 | 2016-02-02 | Stanley Electric Co., Ltd. | Light source device, method for manufacturing the same and filament |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2032173B (en) | 1982-11-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |