CA1305512C - Method of fabricating a composite lamp member - Google Patents
Method of fabricating a composite lamp memberInfo
- Publication number
- CA1305512C CA1305512C CA000552607A CA552607A CA1305512C CA 1305512 C CA1305512 C CA 1305512C CA 000552607 A CA000552607 A CA 000552607A CA 552607 A CA552607 A CA 552607A CA 1305512 C CA1305512 C CA 1305512C
- Authority
- CA
- Canada
- Prior art keywords
- composite
- tungsten
- fabricating
- lamp member
- core
- 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
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/04—Electrodes; Screens; Shields
- H01J61/06—Main electrodes
- H01J61/073—Main electrodes for high-pressure discharge lamps
- H01J61/0735—Main electrodes for high-pressure discharge lamps characterised by the material of the electrode
- H01J61/0737—Main electrodes for high-pressure discharge lamps characterised by the material of the electrode characterised by the electron emissive material
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- Powder Metallurgy (AREA)
- Discharge Lamp (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a method of fabricating a tungsten-based duplex composite member, e.g., wire or rod, which combines the emissive, nonsag, or other desirable qualities of an inner tungsten-based core material with a different combination of properties, for example, resistance to attack, by the presence of a different tungsten-based material as an outer sheath or shell surrounding the core material. In one embodiment of the present invention, an electrode is formed from a duplex composite member, composed of a thoriated tungsten core (W - Th02) and a thin rhenium (Re) shell. Other embodiments of duplex composite members are provided by thoriated tungsten discharge electrodes in which it is desirable to have two different concentrations of thoria (Th02) in the element, a first concentration in the core of the duplex composite member and a second concentration in the shell or surface of the member.
The present invention provides a method of fabricating a tungsten-based duplex composite member, e.g., wire or rod, which combines the emissive, nonsag, or other desirable qualities of an inner tungsten-based core material with a different combination of properties, for example, resistance to attack, by the presence of a different tungsten-based material as an outer sheath or shell surrounding the core material. In one embodiment of the present invention, an electrode is formed from a duplex composite member, composed of a thoriated tungsten core (W - Th02) and a thin rhenium (Re) shell. Other embodiments of duplex composite members are provided by thoriated tungsten discharge electrodes in which it is desirable to have two different concentrations of thoria (Th02) in the element, a first concentration in the core of the duplex composite member and a second concentration in the shell or surface of the member.
Description
~3~S~2 METHOD OF FABRICATING A COMPOSITE LAMP MEMBER
~ACRGROUND OF THE INVENTION
The pre~ent invention is directed to a duplex 15 composite member suitable for use in lamps? as either an electrode and/or a filament element. This duplex composite memb~r has two component parts~ a core composed of one type of tunqsten-ba~ed material, and t2) a shell composed of a different tungsten-based 20 material.
The duplex composite member of the present invention may have desirable surface properties such a~
resistance to chemical a~tack and/or mechanical shock 25 and vibration, making it especially well suited for applications in incandescent lamps, metal hal ide di~charge l;amps~ and/or halogen inc:andescent lamps.
Electrode and~or ~ilament failure due to mechani cal 30 shock and/or chemical attack is a recognized proble~ in the li~hting industry. For example, U.S. Paten~ t~o.
4 ,413 ,205 describes in detail how the tungsten conductors 'co the coiled filament ~f a h~l oqen incandescent lamp are locally pitted and chemical ly attacked by bromine in such a manner that ~hey break , ~
' ~3~155~L2 ~2--and the lamp fails.
The 4 ,413 ,205 patent suggests one method for reducing this chemical al:tack problem, namely, modifying the conductor material to a tungsten rhenium (Re) alloy containing at least 0.1~ Re.
Similarly, it is known that filament and/or electrode failure due to chemical attaok can also occur in metal halide high intensity discharge (HID) lamps, especially where reactive halogens, includi~g bromine, chlorine, and lodine have been used. See, for example J. F. Waymouth9 ~Electric Discharge Lamps~ pg. 210, (1971).
The chemical attack of thoriated tungsten electrode rods thus constitutes a recognized obstacle in the ~;~ application of the reactive halogens in metal halide discharge lamps.
: 20 Although such changes in electrode composition as those described in th~ 4,413,205 patent may overcome t he problem of electrode failure due to chemical attack, such alloys suffer from two major shortcomings:
(a) they do not possess the necessary emissive : : : charact:eristics of the W - (usually 1 - 2~ ) ThO2 materials typic211y used for electrodes : ~ and ~ 30 -~ (b~ they introduce excessive Re emiSsion into ehe light emitting ~plasma discharge of ~etal - hal ide lamps.
, ,~,,, ' -3- ~3~
The present invention is directed to an alternate solution to the problems of chemical attack and/or mechanical shock of electrodes and/or filaments, which does not suffer the disadvantages discussed above.
The method according to one embodiment of the present invention provides a tungsten-based duplex composite member, e.g., wire or rod, which combines the emissive, nonsag, or other desirable qualities of an inner tungsten-based core material with a different cornbination of properties, for example, resistance to corrosive attack, by the presence of a different tungsten-based material as an outer sheath or shell surrounding the core material.
One example of the benefits which may be conferred by the present invention is exemplified by the manner in which the aforementioned difficulties of the prior art may be avoided. In one embodiment of the present invention, an electrode is formed from a duplex composite member, composed of a thoriated tungsten core (W - Th02~ and a thin tungsten-rhenium (Re) shell. In this embodiment, any rhenium emission is limited to an insigniicant amount (i.e., that vaporized from the thin shell, especially at the tip of the electrode).
Other embodiments of duplex composite members are provided by thoriated tungsten discharge electrodes in which it is desirable to have two different concentrations of thoria (Th02) in the element, a first concentration in the core of the duplex composite member and a second concentration in the shell or SSi~Z
surface of the member. In preferred embodiment6, the thoria concentration in the shell portion of the duplex composite may be either lower or high than the thoria concentration ~n the core portion.
; 5 One desirable objective which can be facilitated hy the use of the duplex composite member of the present invention is the ability to draw thoriated core tungsten to much finer sizes ~i.e., smaller diameters) than heretofore feasible.
Prior to the present invention, the l:Lmit of wire slzes for thoriated tungsten ~with much greater than about 1% ThO2) was no lower than about 0.020 inch in : 15 diameter. By utilizing a duplex composite member of the present invent~on composed of a 2~ thoriated tungsten core with a 1% thoriated tungsten shell, drawn wire of 00017 ln~hes in diameter has readily been prepared. Unlike the 0.020 inch diameter wire . previously prepared, this 0.017 inch diameter wire is especially well ~uited for use in: 1QW w~ttage ~etal halide lamps, i~e. 40 to 100 watts.
.:
: 25 DETAILE~ DESCRIPTION OF THE PREFERRED EMBODI~ENTS
~, .
: . As se~ forth above, the present invention provides :~ a tungsten based auplex composite member, e~g., wire or : r~d, which combines the .emissive, nonsag, -or other . 30 desirable qualities o~ an inner~ tungsten-based core material, with: a different combination of properties, for example, resistance to attack, by the presence of a different tungsten-based material as an outer sheath or shell surrounding th* core material~
.
,.
.. .. .. . . ..
~3~55i~
As used herein, the term ltungsten-based material~
is defined as tungsten-contain;ng compositions suitable for use as filament and/oe electrode members in lamps, especially incandescent lamps, metal halide discharge lamps, and halogen incandescent lamps. Typically tungsten makes up at least about 95 percent (by weight), or more, of such compositions. After careful consideration of the teachings of the present : disclosure, the skilled artisan will readily recogni~e suitable compositions for use herein.
Core materials may include thoriated tu~gstens, for example, tungsten compositions containing thoria in the range of from about 0.5 to about 5.0 percent (by weight). Other types of tungsten-~ased materials which may constitute the core include nondoped, i.e., commercially pure ~CP) tungsten~ potassium t~) doped nonsag tungsten tnormally used in incandescent filaments~, and tungsten alloys. Such materials are known to the skilled ar~isan in the:lightin~ field.
Other core materials include tungsten modified with - emissive materials such as CeO2~ La2O3, ; S~23~ ~f2~ ZrO2, and the like, in concentrations ranging up to about 5 percent (by weight). Combinations of these emitters with and without thoria may also be employed as a tungsten-based . core material herein.
: .
~; 30 ~ Another- example of a useful tungsten~based core material i8 provided by Japanese Patent No. 58-129741 which de~cribes the use o~ a tungsten electrode containing 20 ppm aluminum ~Al). This Al level ~ubstantially exceeds curren~ly specified levels of 55~1L2 thi~ e1ement in wire~.
As shell materlals, any of the above described core materials may be employed, with the proviso that the core material and the shell materiàl of any given duplex composite member are not the same~
In addition, attack and corrosion-resistant tungsten-rhenium alloys may also be used as shell materials. Such ~Re)alloys, contain.ing up to about 5%
Re (by weight~ will a1so promote mechanical shock and vibration resistance, making the duplex composite member especially well suited for use as incandescent ~ilaments for applications involving ~uch shock and vibrationr while minimizing the amount of expensive Re which must be used and enhancing the 1uminous efficacy by the use of a R-doped, nonsag core.
Such a combination with a tungsten-rhenium ~-Re) shell around a pota6sium ~R~-doped, nonsag core enables the composite to be used as the fi1ament of a ha1Ogen incandescent lamp, in which separate internal conductors are not required.~
. In general, duplex composites are prepared by i~ostatically cold pressing the preblended and : . : preplaced powders: together into a billet with the core preplaced concentrically within the shell. The bil let : is: then: densified ~by ~sintering at a high temperature ~ 30 and reduced to wire of the desired diameters by the : :~ usual tungsten processing methods of rolling, swaying, and drawing.
: :
The present invention will be further illustrated with reference to the followin~ examples which will aid , ., ~3~55i~
~n the understanding of the present invention, bbt which are not to be construed as limitation~ thereof.
All percentage~ reported herein, unless otherwise specified, are percent by weight. All temperatures are expressed in degrees Celsius~
EXAMPLE I
Duplex composite electrodes with a 2% thoria core inside a 1% thoria shell were prepared for testing in both 1~0 wat~ and 400 watt metal halide :lamps (Sylvania Metalarc lamps).
When viewed as a polished cross-section, the 2%
thoria core is clearly revealed in contra~t to the 1 thoria shell, which has a much coarser grain structure, ~: bein~ attributed to the larger grain size following the ` previous reccystallization-anneal.
: 20 : The mold used in thi~ exa~ple consisted of three main sections, a cylindrically shaped outer PVC mold ~: ~ support tube ~2.25 in. I.D. x 20 in.)7 a cylindrically shaped outer mold member 12 in. I~Do x 24 in~) and a : 25 cylindrically Ehaped stain~ess steel inner mold/fill ; tube (1 in. x 36 in.).
A portion of the ~upper :section of the stainless : ~ steel inne~ moldJfill tube was flared out to a diameter : 30 of 2 in. to act as a funnel for the introduction of powders. At the bottom of the outer PVC mold support tube was placed a segment of hard rubber, which acted : as a shock absorber.
:~ ' , ,, ~ ~ ,,, .; . ,~, .
~3~55~
The three component parts were concentrically fitted together and filling was conducl:ed as de~cribed below.
The procedure used to prepare this duplex composite S started by adding 3,000 gra~s of W 2~ ThO2 powder to ; the central fill tube of the mold described above. At the same time, lyO00 grams of W-1% ThO2 powder was placed in the space between the mold and the central fill tube.
The entire assembly was gently tapped during the ~ filling operation until the prescribed amounts o~ both : powders were added to the mold. At the end of the filling operation the levels of powder in the core and the outer shell were approximately the same. One critical aspect of filling i8 that the powders are only loosely packed into the mold since tight packing ; ~ prevents the removal of the central filling tubq.
: ~ 20 After filling and the extraction of:the fill tube, the~ mold wa~ sealed, then cold i~ostatically pres d at a: pressure of approxi~ately 45~000 lbs per square ch. The pressed powder compact was then ~olid state sintered for ~about 12 hours at about~ ~ C----in a hydrogen atmosphere producing a composite ingot weighing about 13 kg with a density of 17.6 y/cc, i.e., about 93% of the theoretical density.
The resulting~ :ingot was: about 1.5 inches in ~diameter by about 19 inches long. The W 1% ThO2 : shell comprised ~about 70% of the ingot volume with the 2% ThO2 ~making~ up~the remainder, producing an ingot with an~average ThO2~content of 1034% by analysis.
:
:
L3055~l~
_9_ Reduction of the ingot began first by rolling on a two high rolling mill from 1.5 to 1.0 inch in diameter in multiple-passPs at a temperature above 1300~C.
Atee recrystallization, the :Lngot was rolled twice at a temperature above 1400C on a multiple stand rolling mill ~anufactured by Frederick Xocks Co~ f to a diameter of about 0.3 inch with an intermediate recrystallization.
The ingot was further reduced to about 0.1 inch diameter by multiple-pass swaging with three more receystallization anneals. Because the diffusivity of ThO2 in tungsten is very low for all o~ the processing temperatures employed herein, the interface between the W-l~ ThO2 outer ~hell and the ~-2% ThO2 core remains distinct, maintaining the duplex composite structure. Below 0.1 inch diameter the ingot was drawn into wire using conventional wiredrawing practices for W-ThO2 wire.
: 20 :
: The duplex composite wire made thereby was drawn to ; 0-039 inch diameter. Cathode rods for 400 watt metal : halide~ lamps were prepared theréfrom by centerless grinding to 0.0365 inch diameter and sectioning the : 25 ground rods into 1/2 inch lengths. These members were:uæed to prepare seventeen 400 watt Metalarc-type lamps (havin~ an a~c tube fill comprising Na, Sc, I, and ~9) each of : which~ lighted ~and operated normally in accordance with:their design ratings. :
~ACRGROUND OF THE INVENTION
The pre~ent invention is directed to a duplex 15 composite member suitable for use in lamps? as either an electrode and/or a filament element. This duplex composite memb~r has two component parts~ a core composed of one type of tunqsten-ba~ed material, and t2) a shell composed of a different tungsten-based 20 material.
The duplex composite member of the present invention may have desirable surface properties such a~
resistance to chemical a~tack and/or mechanical shock 25 and vibration, making it especially well suited for applications in incandescent lamps, metal hal ide di~charge l;amps~ and/or halogen inc:andescent lamps.
Electrode and~or ~ilament failure due to mechani cal 30 shock and/or chemical attack is a recognized proble~ in the li~hting industry. For example, U.S. Paten~ t~o.
4 ,413 ,205 describes in detail how the tungsten conductors 'co the coiled filament ~f a h~l oqen incandescent lamp are locally pitted and chemical ly attacked by bromine in such a manner that ~hey break , ~
' ~3~155~L2 ~2--and the lamp fails.
The 4 ,413 ,205 patent suggests one method for reducing this chemical al:tack problem, namely, modifying the conductor material to a tungsten rhenium (Re) alloy containing at least 0.1~ Re.
Similarly, it is known that filament and/or electrode failure due to chemical attaok can also occur in metal halide high intensity discharge (HID) lamps, especially where reactive halogens, includi~g bromine, chlorine, and lodine have been used. See, for example J. F. Waymouth9 ~Electric Discharge Lamps~ pg. 210, (1971).
The chemical attack of thoriated tungsten electrode rods thus constitutes a recognized obstacle in the ~;~ application of the reactive halogens in metal halide discharge lamps.
: 20 Although such changes in electrode composition as those described in th~ 4,413,205 patent may overcome t he problem of electrode failure due to chemical attack, such alloys suffer from two major shortcomings:
(a) they do not possess the necessary emissive : : : charact:eristics of the W - (usually 1 - 2~ ) ThO2 materials typic211y used for electrodes : ~ and ~ 30 -~ (b~ they introduce excessive Re emiSsion into ehe light emitting ~plasma discharge of ~etal - hal ide lamps.
, ,~,,, ' -3- ~3~
The present invention is directed to an alternate solution to the problems of chemical attack and/or mechanical shock of electrodes and/or filaments, which does not suffer the disadvantages discussed above.
The method according to one embodiment of the present invention provides a tungsten-based duplex composite member, e.g., wire or rod, which combines the emissive, nonsag, or other desirable qualities of an inner tungsten-based core material with a different cornbination of properties, for example, resistance to corrosive attack, by the presence of a different tungsten-based material as an outer sheath or shell surrounding the core material.
One example of the benefits which may be conferred by the present invention is exemplified by the manner in which the aforementioned difficulties of the prior art may be avoided. In one embodiment of the present invention, an electrode is formed from a duplex composite member, composed of a thoriated tungsten core (W - Th02~ and a thin tungsten-rhenium (Re) shell. In this embodiment, any rhenium emission is limited to an insigniicant amount (i.e., that vaporized from the thin shell, especially at the tip of the electrode).
Other embodiments of duplex composite members are provided by thoriated tungsten discharge electrodes in which it is desirable to have two different concentrations of thoria (Th02) in the element, a first concentration in the core of the duplex composite member and a second concentration in the shell or SSi~Z
surface of the member. In preferred embodiment6, the thoria concentration in the shell portion of the duplex composite may be either lower or high than the thoria concentration ~n the core portion.
; 5 One desirable objective which can be facilitated hy the use of the duplex composite member of the present invention is the ability to draw thoriated core tungsten to much finer sizes ~i.e., smaller diameters) than heretofore feasible.
Prior to the present invention, the l:Lmit of wire slzes for thoriated tungsten ~with much greater than about 1% ThO2) was no lower than about 0.020 inch in : 15 diameter. By utilizing a duplex composite member of the present invent~on composed of a 2~ thoriated tungsten core with a 1% thoriated tungsten shell, drawn wire of 00017 ln~hes in diameter has readily been prepared. Unlike the 0.020 inch diameter wire . previously prepared, this 0.017 inch diameter wire is especially well ~uited for use in: 1QW w~ttage ~etal halide lamps, i~e. 40 to 100 watts.
.:
: 25 DETAILE~ DESCRIPTION OF THE PREFERRED EMBODI~ENTS
~, .
: . As se~ forth above, the present invention provides :~ a tungsten based auplex composite member, e~g., wire or : r~d, which combines the .emissive, nonsag, -or other . 30 desirable qualities o~ an inner~ tungsten-based core material, with: a different combination of properties, for example, resistance to attack, by the presence of a different tungsten-based material as an outer sheath or shell surrounding th* core material~
.
,.
.. .. .. . . ..
~3~55i~
As used herein, the term ltungsten-based material~
is defined as tungsten-contain;ng compositions suitable for use as filament and/oe electrode members in lamps, especially incandescent lamps, metal halide discharge lamps, and halogen incandescent lamps. Typically tungsten makes up at least about 95 percent (by weight), or more, of such compositions. After careful consideration of the teachings of the present : disclosure, the skilled artisan will readily recogni~e suitable compositions for use herein.
Core materials may include thoriated tu~gstens, for example, tungsten compositions containing thoria in the range of from about 0.5 to about 5.0 percent (by weight). Other types of tungsten-~ased materials which may constitute the core include nondoped, i.e., commercially pure ~CP) tungsten~ potassium t~) doped nonsag tungsten tnormally used in incandescent filaments~, and tungsten alloys. Such materials are known to the skilled ar~isan in the:lightin~ field.
Other core materials include tungsten modified with - emissive materials such as CeO2~ La2O3, ; S~23~ ~f2~ ZrO2, and the like, in concentrations ranging up to about 5 percent (by weight). Combinations of these emitters with and without thoria may also be employed as a tungsten-based . core material herein.
: .
~; 30 ~ Another- example of a useful tungsten~based core material i8 provided by Japanese Patent No. 58-129741 which de~cribes the use o~ a tungsten electrode containing 20 ppm aluminum ~Al). This Al level ~ubstantially exceeds curren~ly specified levels of 55~1L2 thi~ e1ement in wire~.
As shell materlals, any of the above described core materials may be employed, with the proviso that the core material and the shell materiàl of any given duplex composite member are not the same~
In addition, attack and corrosion-resistant tungsten-rhenium alloys may also be used as shell materials. Such ~Re)alloys, contain.ing up to about 5%
Re (by weight~ will a1so promote mechanical shock and vibration resistance, making the duplex composite member especially well suited for use as incandescent ~ilaments for applications involving ~uch shock and vibrationr while minimizing the amount of expensive Re which must be used and enhancing the 1uminous efficacy by the use of a R-doped, nonsag core.
Such a combination with a tungsten-rhenium ~-Re) shell around a pota6sium ~R~-doped, nonsag core enables the composite to be used as the fi1ament of a ha1Ogen incandescent lamp, in which separate internal conductors are not required.~
. In general, duplex composites are prepared by i~ostatically cold pressing the preblended and : . : preplaced powders: together into a billet with the core preplaced concentrically within the shell. The bil let : is: then: densified ~by ~sintering at a high temperature ~ 30 and reduced to wire of the desired diameters by the : :~ usual tungsten processing methods of rolling, swaying, and drawing.
: :
The present invention will be further illustrated with reference to the followin~ examples which will aid , ., ~3~55i~
~n the understanding of the present invention, bbt which are not to be construed as limitation~ thereof.
All percentage~ reported herein, unless otherwise specified, are percent by weight. All temperatures are expressed in degrees Celsius~
EXAMPLE I
Duplex composite electrodes with a 2% thoria core inside a 1% thoria shell were prepared for testing in both 1~0 wat~ and 400 watt metal halide :lamps (Sylvania Metalarc lamps).
When viewed as a polished cross-section, the 2%
thoria core is clearly revealed in contra~t to the 1 thoria shell, which has a much coarser grain structure, ~: bein~ attributed to the larger grain size following the ` previous reccystallization-anneal.
: 20 : The mold used in thi~ exa~ple consisted of three main sections, a cylindrically shaped outer PVC mold ~: ~ support tube ~2.25 in. I.D. x 20 in.)7 a cylindrically shaped outer mold member 12 in. I~Do x 24 in~) and a : 25 cylindrically Ehaped stain~ess steel inner mold/fill ; tube (1 in. x 36 in.).
A portion of the ~upper :section of the stainless : ~ steel inne~ moldJfill tube was flared out to a diameter : 30 of 2 in. to act as a funnel for the introduction of powders. At the bottom of the outer PVC mold support tube was placed a segment of hard rubber, which acted : as a shock absorber.
:~ ' , ,, ~ ~ ,,, .; . ,~, .
~3~55~
The three component parts were concentrically fitted together and filling was conducl:ed as de~cribed below.
The procedure used to prepare this duplex composite S started by adding 3,000 gra~s of W 2~ ThO2 powder to ; the central fill tube of the mold described above. At the same time, lyO00 grams of W-1% ThO2 powder was placed in the space between the mold and the central fill tube.
The entire assembly was gently tapped during the ~ filling operation until the prescribed amounts o~ both : powders were added to the mold. At the end of the filling operation the levels of powder in the core and the outer shell were approximately the same. One critical aspect of filling i8 that the powders are only loosely packed into the mold since tight packing ; ~ prevents the removal of the central filling tubq.
: ~ 20 After filling and the extraction of:the fill tube, the~ mold wa~ sealed, then cold i~ostatically pres d at a: pressure of approxi~ately 45~000 lbs per square ch. The pressed powder compact was then ~olid state sintered for ~about 12 hours at about~ ~ C----in a hydrogen atmosphere producing a composite ingot weighing about 13 kg with a density of 17.6 y/cc, i.e., about 93% of the theoretical density.
The resulting~ :ingot was: about 1.5 inches in ~diameter by about 19 inches long. The W 1% ThO2 : shell comprised ~about 70% of the ingot volume with the 2% ThO2 ~making~ up~the remainder, producing an ingot with an~average ThO2~content of 1034% by analysis.
:
:
L3055~l~
_9_ Reduction of the ingot began first by rolling on a two high rolling mill from 1.5 to 1.0 inch in diameter in multiple-passPs at a temperature above 1300~C.
Atee recrystallization, the :Lngot was rolled twice at a temperature above 1400C on a multiple stand rolling mill ~anufactured by Frederick Xocks Co~ f to a diameter of about 0.3 inch with an intermediate recrystallization.
The ingot was further reduced to about 0.1 inch diameter by multiple-pass swaging with three more receystallization anneals. Because the diffusivity of ThO2 in tungsten is very low for all o~ the processing temperatures employed herein, the interface between the W-l~ ThO2 outer ~hell and the ~-2% ThO2 core remains distinct, maintaining the duplex composite structure. Below 0.1 inch diameter the ingot was drawn into wire using conventional wiredrawing practices for W-ThO2 wire.
: 20 :
: The duplex composite wire made thereby was drawn to ; 0-039 inch diameter. Cathode rods for 400 watt metal : halide~ lamps were prepared theréfrom by centerless grinding to 0.0365 inch diameter and sectioning the : 25 ground rods into 1/2 inch lengths. These members were:uæed to prepare seventeen 400 watt Metalarc-type lamps (havin~ an a~c tube fill comprising Na, Sc, I, and ~9) each of : which~ lighted ~and operated normally in accordance with:their design ratings. :
3~ : : ::
:: : :
The remaind~er of the 0~039 inch wire was drawn further to a diameter of~ 0.017 inch and this drawn wire was se~cti:oned into 0~0295~inch segments. These small : segment~ weYe used ~o prepare five 100 watt metal ,". ,,; " ..,,, . , . ~ .
~: .
~3~ 2 halide lamps, also having an arc tube fill comprising Na7 Sc, I, and Hg. These lamps operated normally after burning for over 2000 hours. They were also ~ound to start slightly faster than the standard lamps having a 1% thoria cathode, in this case 91 seconds versus 95 seconds.
EXAMPLE II
1~
A duplex composite member is al80 prepared, using essentially the same procedures set forth in Example I, but with a non-thoriated core of tungsten encased in a shell of 2% thoria. lO0 Watt Metalarc type lamps made therefrom are found to start much faster than the standard Metalarc lamps having a 1% thoria electrode.
The lamps will also demonstrate improved lumen maintenance~ especially when compared to prior art lamps with the same rapid star:ting characteristics, but ;~ : 20 wherein 2% thoriated tungsten makes ~p the entire electrode.
~he present invention has been described in detail, ineluding the preferred embodiments thereof. However, 25 : it will be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and/or improvements on this invention and still be within the scope and spirit of this inYention a~ set forth in the following claims.
3~ ~
,~,,, ~ . , , ~, :
. ~
~ .
:: : :
The remaind~er of the 0~039 inch wire was drawn further to a diameter of~ 0.017 inch and this drawn wire was se~cti:oned into 0~0295~inch segments. These small : segment~ weYe used ~o prepare five 100 watt metal ,". ,,; " ..,,, . , . ~ .
~: .
~3~ 2 halide lamps, also having an arc tube fill comprising Na7 Sc, I, and Hg. These lamps operated normally after burning for over 2000 hours. They were also ~ound to start slightly faster than the standard lamps having a 1% thoria cathode, in this case 91 seconds versus 95 seconds.
EXAMPLE II
1~
A duplex composite member is al80 prepared, using essentially the same procedures set forth in Example I, but with a non-thoriated core of tungsten encased in a shell of 2% thoria. lO0 Watt Metalarc type lamps made therefrom are found to start much faster than the standard Metalarc lamps having a 1% thoria electrode.
The lamps will also demonstrate improved lumen maintenance~ especially when compared to prior art lamps with the same rapid star:ting characteristics, but ;~ : 20 wherein 2% thoriated tungsten makes ~p the entire electrode.
~he present invention has been described in detail, ineluding the preferred embodiments thereof. However, 25 : it will be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and/or improvements on this invention and still be within the scope and spirit of this inYention a~ set forth in the following claims.
3~ ~
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. ~
~ .
Claims (9)
1. A method of fabricating a composite lamp member, said member including a core formed from a first compacted tungsten-based material and a shell intimately bonded to the outer surface of said core, said shell being formed from a second compacted tungsten-based material, said method comprising the following steps:
(a) inserting said first tungsten-based material within a centered fill tube of a cylindrical mold;
(b) inserting said second tungsten-based material in powder form into the space surrounding said fill tube and within said mold;
(c) extracting said fill tube from said mold such that a composite cylindrical billet is formed within said mold;
(d) removing said billet from said mold;
(e) cold pressing said billet isostatically;
(f) sintering said billet thereby forming a composite ingot; and (g) rolling, swaging, and drawing said composite ingot thereby forming a composite wire; and (h) forming said composite lamp member from said wire.
(a) inserting said first tungsten-based material within a centered fill tube of a cylindrical mold;
(b) inserting said second tungsten-based material in powder form into the space surrounding said fill tube and within said mold;
(c) extracting said fill tube from said mold such that a composite cylindrical billet is formed within said mold;
(d) removing said billet from said mold;
(e) cold pressing said billet isostatically;
(f) sintering said billet thereby forming a composite ingot; and (g) rolling, swaging, and drawing said composite ingot thereby forming a composite wire; and (h) forming said composite lamp member from said wire.
2. A method of fabricating a composite lamp member as described in claim 1 wherein said shell includes a material selected from the group consisting of thorium and rhenium in an amount approximately equal to five percent or less by weight.
3. A method of fabricating a composite lamp member as described in claim 2 wherein said core consists essentially of tungsten.
4. A method of fabricating a composite lamp member as described in claim 1 wherein said core and said shell both include the same material selected from the group consisting of thorium and rhenium in different amounts.
5. A method of fabricating a composite lamp member as described in claim 1 wherein said cold isostatic pressing of said composite billet is performed at approximately 45,000 pounds per square inch.
6. A method of fabricating a composite lamp member as described in claim 1 wherein said sintering of said billet lasts approximately twelve hours at approximately 2,100 degrees Celsius.
7. A method of fabricating a composite lamp member as described in claim 1 wherein said composite ingot has a density of approximately 93 percent of its theoretical density.
8. A method of fabricating a composite lamp member as described in claim 1 wherein said composite wire has a cross-sectional diameter of approximately 0.039 inch.
9. A method of fabricating a composite lamp member as described in claim 1 wherein said composite wire has a cross-sectional diameter of approximately 0.017 inch.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US94574686A | 1986-12-22 | 1986-12-22 | |
| US945,746 | 1986-12-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1305512C true CA1305512C (en) | 1992-07-21 |
Family
ID=25483499
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000552607A Expired - Lifetime CA1305512C (en) | 1986-12-22 | 1987-11-24 | Method of fabricating a composite lamp member |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0272687B1 (en) |
| JP (1) | JPS63168963A (en) |
| CA (1) | CA1305512C (en) |
| DE (1) | DE3751379T2 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03110748A (en) * | 1989-09-22 | 1991-05-10 | Stanley Electric Co Ltd | Electric discharge lamp |
| JPH03274649A (en) * | 1990-03-26 | 1991-12-05 | Ushio Inc | Electrode and its manufacture |
| GB9413973D0 (en) * | 1994-07-11 | 1994-08-31 | Rank Brimar Ltd | Electrode structure |
| KR100664601B1 (en) | 1999-08-22 | 2007-01-04 | 이페2하 아게 | Light source |
| JP4896288B2 (en) * | 2000-04-20 | 2012-03-14 | 株式会社東芝 | Electron emitting electrode, manufacturing method thereof, and discharge lamp using the same |
| KR100426566B1 (en) * | 2001-08-08 | 2004-04-08 | 엘지.필립스디스플레이(주) | Color Cathode-ray Tube Containing Improved Inner Shield |
| JP2014063667A (en) | 2012-09-21 | 2014-04-10 | Stanley Electric Co Ltd | Incandescent lamp |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL230714A (en) * | 1958-08-21 | |||
| FR1464066A (en) * | 1965-11-17 | 1966-07-22 | Pat & Visseaux Claude | electrode for electric discharge device |
| JPS5330266A (en) * | 1976-09-02 | 1978-03-22 | Toshiba Corp | Production of direct heated filament |
| GB2050045A (en) * | 1979-05-29 | 1980-12-31 | Emi Varian Ltd | Thermionic cathode |
| JPS5611832A (en) * | 1979-07-11 | 1981-02-05 | Toshiba Corp | Directly heated cathode of electron tube and its manufacture |
| JPS592145B2 (en) * | 1979-10-01 | 1984-01-17 | 株式会社東芝 | short arc light discharge lamp |
| NL8003698A (en) * | 1980-06-26 | 1982-01-18 | Philips Nv | HALOGEN LIGHT. |
| JPS5725664A (en) * | 1980-07-22 | 1982-02-10 | Mitsubishi Electric Corp | Electrode for electric-discharge lamp |
| JPS59130697A (en) * | 1983-01-17 | 1984-07-27 | Iwasaki Electric Co Ltd | Electrode for arc welding |
-
1987
- 1987-11-24 CA CA000552607A patent/CA1305512C/en not_active Expired - Lifetime
- 1987-12-21 JP JP32162587A patent/JPS63168963A/en active Pending
- 1987-12-22 EP EP87119051A patent/EP0272687B1/en not_active Expired - Lifetime
- 1987-12-22 DE DE19873751379 patent/DE3751379T2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0272687B1 (en) | 1995-06-28 |
| EP0272687A2 (en) | 1988-06-29 |
| JPS63168963A (en) | 1988-07-12 |
| DE3751379D1 (en) | 1995-08-03 |
| DE3751379T2 (en) | 1995-11-09 |
| EP0272687A3 (en) | 1990-08-22 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |