JP2004234891A - Sealed rod for discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed rod joined with an electrode for a discharge lamp and sealed with glass, having a thermal expansion coefficient of the same level as a conventional Kovar, and more excellent than that in resistivity and thermal conductivity, without defects such as a crack. <P>SOLUTION: The sealed rod 4 for the discharge lamp sealed in an end part of a glass bulb 2 with one end connected to the electrode 3 and the other to an outer lead wire 6 has tungsten and/or molybdenum as a main ingredient and contains one or two or more kinds out of a group consisting of nickel, iron, copper, and cobalt by 0.01 to 10% in weight ratio. It is preferable to contain phosphorus by 0.5 to 10% in weight ratio against the content of one or two or more kinds out of a group consisting of nickel, iron, copper and cobalt. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sealing rod in a discharge lamp such as a cold cathode fluorescent lamp used as a backlight of a liquid crystal display (LCD) such as a television receiver or a personal computer.
[0002]
[Prior art]
A liquid crystal display (LCD) used in OA equipment such as a personal computer and a word processor incorporates a backlight using a cold cathode fluorescent lamp as a light source for illuminating the LCD.
[0003]
The electrode portion of a cold cathode fluorescent lamp or the like is composed of an electrode portion, a sealing rod (sealing wire portion), and an external lead wire. Kovar has been conventionally employed as the sealing rod. The Kovar sealing rod is connected to the electrode by resistance welding or the like.
[0004]
In recent years, due to demands for larger, thinner, higher brightness, and lower power consumption screens in liquid crystal televisions, they are longer (1000 mm for longer) and thinner (outer diameter for thinner) than cold cathode trend lamps. 2 mm), brighter and more efficient. For this reason, a rod having a low specific resistance and a high thermal conductivity is also required for the sealing rod. However, the conventional Kovar has a problem that the voltage loss and the heat generation are large because the specific resistance is relatively high and the thermal conductivity is relatively low.
[0005]
Therefore, tungsten or molybdenum, which has a similar thermal expansion coefficient to Kovar, a lower specific resistance than Kovar, and a higher thermal conductivity, have come to be used. The thermal expansion coefficient of Kovar is 5.3 × 10 ^-6 / K, 4.5 × 10 for tungsten ^-6 / K, molybdenum is 5.1 × 10 ^-6 / K.
[0006]
On the other hand, the specific resistance was 4.9 × 10 for Kovar. ^-5 Ωcm whereas tungsten is 5.4 × 10 ^-5 Ωcm, molybdenum is 5.7 × 10 ^-5 Ωcm. The thermal conductivity is 17 W / mK for Kovar, 167 W / mK for tungsten, and 159 W / mK for molybdenum.
[0007]
[Problems to be solved by the invention]
However, since tungsten and molybdenum have a high melting point, they cannot be formed by a method such as casting, but are manufactured by a so-called powder metallurgy method in which powder is formed and sintered. This sintered body is formed into a rod shape by rolling and drawing, but cracks and streaks in the longitudinal direction are likely to occur during the working. This problem is more likely to occur with high hardness and brittle tungsten.
[0008]
If the cracks or streaks in the longitudinal direction are present in the sealing rod, they cannot be completely sealed by the glass, so that the air flows into the discharge lamp tube (the internal pressure is, for example, about 0.1 atm) through these defects. , Which contributed to product failure. If these cracks and other defects are large, they can be found by inspection at the time of shipment of the cold-cathode tube.However, in the case of fine cracks, the air gradually enters, so the lamp is built into the backlight and further built into the liquid crystal display device. In some cases, the damage appeared at the stage, and the amount of damage could be enormous.
[0009]
Due to such problems, the reliability of a cold cathode fluorescent lamp using a tungsten or molybdenum sealed rod has been insufficient. In addition, for a sealing rod made of tungsten or molybdenum, a large cost is required for crack inspection in the manufacturing process, which has contributed to an increase in the cost of the cold cathode fluorescent lamp. Further, the high sintering temperature in the tungsten production process and the tapping and drawing processes in the production of tungsten and molybdenum also contributed to the cost increase.
[0010]
Therefore, the present invention provides a sealing rod having a thermal expansion coefficient similar to that of Kovar, and having a specific resistance and thermal conductivity close to that of tungsten or molybdenum, and having no defects such as cracks in the longitudinal direction. The task is to provide.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs the following configuration. That is, the sealing rod for a discharge lamp according to the present invention is a sealing rod that is sealed at an end of a glass bulb, one end of which is connected to an electrode, and the other end of which is connected to an external lead wire. And / or molybdenum as a main component, characterized in that it contains 0.01 to 10% by weight of one or more of the group consisting of nickel, iron, copper and cobalt.
[0012]
This discharge lamp sealing rod is made of tungsten and / or molybdenum as a main component and eliminates cracks and the like introduced during the stamping and drawing steps during the manufacturing process, and is manufactured without going through the stamping and drawing steps. Is what you can do.
[0013]
In this type of sealing rod, the relative density needs to be 95% or more, preferably 98% or more in order to ensure sealing. Therefore, the composition of the sintered tungsten alloy or the sintered molybdenum alloy is a composition that can easily achieve a high density at a relatively low temperature, that is, tungsten, molybdenum, or the like as a main component, and one or two of nickel, iron, copper, and cobalt. The composition was composed of at least species. In order to obtain a high sintering density at a relatively low sintering temperature, it is preferable to contain 0.5 to 10% by weight of phosphorus based on the content of nickel, iron, copper, cobalt and the like. As a result of the experiment, for example, in a W-3Ni-2Cu alloy, when the amount of phosphorus relative to the amount of nickel and copper was 2%, the sintering density was 98% even when the sintering temperature was changed from 1400 ° C to 1000 ° C. If the amount of phosphorus is less than the above range, the effect of improving the sinterability cannot be obtained, and if the amount is too large, the specific resistance tends to increase and the thermal conductivity tends to decrease. is there.
[0014]
Furthermore, in the case of tungsten-molybdenum sintered bonding gold, it is made of one or more of nickel, iron, copper, cobalt, and phosphorus similarly to the above molybdenum. Since molybdenum can be sintered at a relatively low temperature as compared with tungsten, pure molybdenum can be used in some cases. Since the oxide of molybdenum dissolves in the glass, the material containing molybdenum has a good sealing property with respect to the glass.
[0015]
The selection of these tungsten alloys, molybdenum alloys, and tungsten-molybdenum alloys may be made according to the thermal expansion coefficient of the glass used for the discharge lamp. The content of nickel, iron, copper, cobalt, phosphorus and the like is preferably 0.01 to 10% by weight in total. Since an electrode or a lead wire is welded to the sealing rod, it is preferable to form a convex portion or a concave portion at the end so that the welding can be performed well. If a convex portion is formed at the weld end, welding is easy because the cross-sectional area is small, and burrs are less likely to occur. Further, if a recess is formed at the welded end, it is possible to prevent the burrs of the gimette wire, which is the lead wire, from spreading laterally, and the glass can be easily wound.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a specific description will be given based on an embodiment of the present invention illustrated in the drawings. FIG. 1 is a partial sectional view of a cold cathode fluorescent lamp. The fluorescent lamp 1 is, for example, a straight tube having an outer diameter of about 2.6 mm, an inner diameter of 1.6 mm, and a length of about 400 mm. Enclosures 7 are provided at both ends of the tube-shaped glass bulb 2, and an encapsulation rod 4 having a cup-shaped electrode 3 joined at the tip thereof has a thermal expansion coefficient of 5 to 5.5 × 10. ^-6 / K of borosilicate glass or aluminosilicate glass.
[0017]
The sealing rod 4 is made of sintered tungsten alloy, sintered molybdenum alloy (in some cases, sintered molybdenum can be used), or sintered tungsten-molybdenum alloy. The same applies to the case of a molybdenum alloy or the like.
[0018]
The dimensions of the sealing rod 4 are, for example, an outer diameter of about 0.8 mm and a length of about 2.4 mm. The electrode 3 has a cup shape with an outer diameter of 1.2 mm and an inner diameter of 0.9 mm, a length of about 3 mm, and is resistance-welded to the sealing rod 4. The external lead wire 6 is a gimette wire and is resistance-welded to the sealing rod 4.
[0019]
The sealing rod 4 is manufactured, for example, as follows. First, tungsten powder, nickel powder, and copper powder are mixed in a V blender, and then dried. An organic binder is added to the mixed powder and kneaded to obtain a feedstock for injection molding. This feedstock is put into an injection molding machine and injection-molded into a predetermined mold. The obtained molded body is degreased and pre-sintered by gradually increasing the temperature to 700 ° C. in a hydrogen atmosphere. Thereafter, by sintering at 1400 ° C. in a hydrogen atmosphere, a sealing rod made of a sintered tungsten alloy having a relative density of about 98% can be obtained.
[0020]
Embodiment 1
Tungsten powder with an average particle size of 1.8 microns, 1.8 wt% of carbonyl nickel powder with an average particle size of 5 microns, and 1.2 wt% of electrolytic copper powder with an average particle size of 13 microns were mixed in a V blender. The mixed powder was mixed with a copolymer of ethylene vinyl acetate, butyl methacrylate, and polystyrene, which is an organic binder for injection molding, paraffin wax, butyl phthalate, and stearic acid, and kneaded to obtain a feedstock for metal powder injection molding. . This was put into an injection molding machine, heated to 150 to 160 ° C., and then injection molded in a predetermined mold. The dimensions of the obtained molded body were 1.04 mm in diameter and 3.12 mm in length.
[0021]
The obtained molded body was sintered at 1400 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 0.8 mm and a length of 2.4 mm. The relative density of the obtained sintered body was 98.5%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0022]
The coefficient of thermal expansion of the obtained sintered tungsten alloy is 4.8 × 10 ^-6 / K, an intermediate value between Kovar and the conventional production method of tungsten, and there was no trouble in glass sealing. The specific resistance is 9 × 10 ^-5 / Ωcm, the thermal conductivity was 110 W / mK, which was much better than Kovar.
[0023]
A cup-shaped nickel electrode having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 4 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. The defect rate of resistance welding in the case of using tungsten of the conventional manufacturing method was 0.7%, but in the case of using the present alloy, it decreased to 0.2%. Since the metal structure of the sintered tungsten alloy is composed of a tungsten phase and a matrix made of nickel-copper-tungsten having a lower melting point than tungsten, the resistance weldability is superior to that of pure tungsten. After that, the sealing portion was heated with a heater in a non-oxidizing atmosphere and welded with borosilicate glass. The length of the glass winding was 2 mm, and the outer diameter was about 2 mm.
[0024]
Embodiment 2
Tungsten powder with an average particle size of 1.8 microns, 3 wt% of carbonyl nickel powder with an average particle size of 5 microns, 2 wt% of electrolytic copper powder with an average particle size of 13 microns, and 0.1 wt% of red phosphorus powder together with ethyl alcohol in an attritor Mixed. At the time of mixing, a total of 1.5 wt% of PVP and stearic acid, which are organic binders for press molding, were added. After mixing, the slurry was spray-granulated with a spray drier to obtain a granulated powder. The granulated powder was press-molded in a predetermined press die. The dimensions of the obtained molded body were 1.2 mm in diameter and 3 mm in length.
[0025]
The obtained molded body was gradually heated to 600 ° C. in a hydrogen atmosphere, degreased and pre-sintered. Thereafter, sintering was performed at 1000 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 1 mm and a length of 2.5 mm. The relative density of the obtained sintered body was 98%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0026]
The coefficient of thermal expansion of the obtained sintered tungsten alloy is 5.5 × 10 ^-6 / K was almost the same as that of tungsten of the conventional production method, and there was no problem in glass sealing. The specific resistance is 1.5 × 10 ^-5 / Ωcm, the thermal conductivity is 75 W / mK, and the specific resistance of Kovar is 4.9 × 10 ^-5 / Ωcm, and thermal conductivity of 17 W / mK.
[0027]
A cup-shaped nickel electrode 3 having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 4 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. The defect rate of resistance welding in the case of using tungsten of the conventional manufacturing method was 0.7%, but in the case of using the present alloy, it decreased to 0.15%. Since the metal structure of the sintered tungsten alloy is composed of a matrix composed of a tungsten phase and nickel-copper-phosphorus-tungsten, the resistance weldability is superior to that of pure tungsten. After that, the sealing portion was heated with a heater in a non-oxidizing atmosphere and welded with borosilicate glass 5. The length of the glass winding was 2 mm, and the outer diameter was about 2.2 mm.
[0028]
Embodiment 3
A total of 1.5 wt% of PVP and stearic acid, which are organic binders for press molding, were added to molybdenum powder having an average particle size of 1.2 μm together with ethyl alcohol. After the addition, the slurry was spray-granulated with a spray drier to obtain a granulated powder. The granulated powder was press-molded in a predetermined press die. The dimensions of the obtained molded body were 1.2 mm in diameter and 3 mm in length.
[0029]
The obtained molded body was gradually heated to 800 ° C. in a hydrogen atmosphere, degreased and pre-sintered. Thereafter, sintering was performed at 1900 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 1 mm and a length of 2.5 mm. The relative density of the obtained sintered body was 96%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0030]
The coefficient of thermal expansion of the obtained sintered molybdenum is 5.8 × 10 ^-6 / K was almost the same as that of molybdenum of the conventional production method, and there was no problem in glass sealing. The specific resistance is 6 × 10 ^-5 / Ωcm, the thermal conductivity is 140 W / mK, and the specific resistance of Kovar is 4.9 × 10 ^-5 / Ωcm, and thermal conductivity of 17 W / mK.
[0031]
A cup-shaped nickel electrode 3 having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 5 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. Thereafter, the sealing portion was heated by a heater in a non-oxidizing atmosphere and was welded with aluminoborosilicate glass 5. The length of the glass winding was 2 mm, and the outer diameter was about 2.2 mm.
[0032]
Embodiment 4
Attritor a 2.2 micron average particle size tungsten powder, 5 wt% carbonyl nickel powder with an average particle size of 6 microns, a 2 wt% carbonyl iron powder with an average particle size of 9 microns, and a 1 wt% cobalt powder with an average particle size of 1.6 microns. Mixed in. The mixed powder was mixed with a copolymer of ethylene vinyl acetate, butyl methacrylate, and polystyrene, which is an organic binder for injection molding, paraffin wax, butyl phthalate, and stearic acid, and kneaded to obtain a feedstock for metal powder injection molding. . This was put into an injection molding machine, heated to 150 to 160 ° C., and then injection molded in a predetermined mold. The dimensions of the obtained molded body were 1.04 mm in diameter and 3.77 mm in length.
[0033]
The obtained molded body was gradually heated to 700 ° C. in a hydrogen atmosphere, degreased and pre-sintered. Thereafter, sintering was performed at 1400 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 0.8 mm and a length of 2.9 mm. The relative density of the obtained sintered body was 98.5%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0034]
The coefficient of thermal expansion of the obtained sintered tungsten alloy is 5.7 × 10 ^-6 / K and Kovar were similar, and there was no problem in glass sealing. The specific resistance is 1.5 × 10 ^-5 / Ωcm, the thermal conductivity is 65 W / mK, and the specific resistance of Kovar is 4.9 × 10 ^-5 / Ωcm and thermal conductivity of 17 W / mK.
[0035]
A cup-shaped nickel electrode 3 having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 5 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. The defect rate of resistance welding when the conventional tungsten was used was 0.7%, but when this alloy was used, it decreased to 0.2%. Since the metal structure of the sintered tungsten alloy is composed of a matrix consisting of a tungsten phase and nickel-iron-cobalt-tungsten, the resistance weldability is superior to that of pure tungsten. Further, unlike the conventional method, in order to use the sintered body as it is, as shown in FIG. 3, a convex portion 4a (or concave portion) for reducing the cross-sectional area and improving the resistance weldability may be formed on the end face. Easy. As shown in FIG. 4, the end of the sealing rod 4 has a concave portion 4b (the peripheral portion of the concave portion has a thickness of, for example, 0.1 to 0.2 mm, and a depth of the concave portion is approximately 0.1 to 0.5 mm). Is formed, there is an advantage that the burrs of the zimet wire 6 can be prevented from spreading in the lateral direction, and the glass can be easily wound. Then, the sealing rod 4 as a sintered body was welded with borosilicate glass by heating the sealing portion in a non-oxidizing atmosphere with a heater. The length of the glass winding was 2 mm, and the outer diameter was about 2 mm.
[0036]
Embodiment 5
Molybdenum powder with an average particle size of 2.2 microns, 4 wt% carbonyl nickel powder and 2 wt% copper powder were mixed in a V blender. Methylcellulose and liquid paraffin, which are organic binders for extrusion molding, were added to this mixed powder, and kneaded with water in a kneader. The kneaded body was put into a plunger type extruder and extruded to a diameter of 1.2 mm. The formed body was cut to a predetermined length at a die exit. The dimensions of the obtained molded body were 1.2 mm in diameter and 3.7 mm in length.
[0037]
The obtained molded body was dried in the air at 30 ° C. for 8 hours, and then gradually heated to 800 ° C. in a hydrogen atmosphere, degreased and pre-sintered. Thereafter, sintering was performed at 1400 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 0.9 mm and a length of 2.8 mm. The relative density of the obtained sintered body was 98%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0038]
The coefficient of thermal expansion of the obtained sintered molybdenum alloy is 6.1 × 10 ^-6 / K was almost the same as that of molybdenum of the conventional production method, and there was no problem in glass sealing. The specific resistance is 7 × 10 ^-5 / Ωcm, the thermal conductivity is 95 W / mK, and the specific resistance of Kovar is 4.9 × 10 ^-5 / Ωcm, and thermal conductivity of 17 W / mK.
[0039]
A cup-shaped nickel electrode 3 having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 5 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. Thereafter, the sealing portion was heated by a heater in a non-oxidizing atmosphere and was welded with aluminoborosilicate glass 5. The length of the glass winding was 2 mm, and the outer diameter was about 2.2 mm.
[0040]
Embodiment 6
To a molybdenum powder having an average particle size of 2.2 microns, nickel nitrate equivalent to nickel of 0.2 wt% was dissolved in alcohol and added, and after mixing, the alcohol was dried. After drying, nitrate was reduced and removed at 650 ° C. in a hydrogen atmosphere. To this powder, a total of 1.5 wt% of PVA and stearic acid as organic binders for press molding were added together with ethyl alcohol. After the addition, the slurry was spray-granulated with a spray drier to obtain a granulated powder. This granulated powder was press-molded in a predetermined press die. The dimensions of the obtained molded body were 1.2 mm in diameter and 3.36 mm in length.
[0041]
The obtained molded body was gradually heated to 800 ° C. in a hydrogen atmosphere, degreased and pre-sintered. Thereafter, sintering was performed at 1700 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 1 mm and a length of 2.8 mm. The relative density of the obtained sintered body was 98%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0042]
The coefficient of thermal expansion of the obtained sintered molybdenum alloy is 5.9 × 10 ^-6 / K was almost the same as that of molybdenum of the conventional production method, and there was no problem in glass sealing. The specific resistance is 7 × 10 ^-5 / Ωcm, the thermal conductivity is 120 W / mK, and the specific resistance of Kovar is 4.9 × 10 ^-5 / Ωcm, and thermal conductivity of 17 W / mK.
[0043]
A cup-shaped nickel electrode 3 having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 4.5 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. Thereafter, the sealing portion was heated with a heater in a non-oxidizing atmosphere and was welded with aluminoborosilicate glass. The length of the glass winding was 2 mm, and the outer diameter was about 2.2 mm.
[0044]
Embodiment 7
Nickel nitrate equivalent to 0.02 wt% of nickel was dissolved in alcohol and added to tungsten powder having an average particle size of 1.5 μm, and after mixing, the alcohol was dried. After drying, nitrate was reduced and removed at 650 ° C. in a hydrogen atmosphere. To this powder, a total of 1.5 wt% of PVA and stearic acid as organic binders for press molding were added together with ethyl alcohol. After the addition, the slurry was spray-granulated with a spray drier to obtain a granulated powder. This granulated powder was press-molded in a predetermined press die. The dimensions of the obtained molded body were 1.0 mm in diameter and 3.37 mm in length.
[0045]
The obtained molded body was gradually heated to 800 ° C. in a hydrogen atmosphere, degreased and pre-sintered. Thereafter, sintering was performed at 1800 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 0.8 mm and a length of 2.7 mm. The relative density of the obtained sintered body was 98.5%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0046]
The coefficient of thermal expansion of the obtained sintered body was 4.7 × 10 ^-6 / K was almost the same as that of tungsten of the conventional production method, and there was no problem in glass sealing. The specific resistance is 5.8 × 10 ^-6 / Ωcm, the thermal conductivity is 130 W / mK, and the specific resistance of Kovar is 4.9 × 10 ^-5 / Ωcm, and thermal conductivity of 17 W / mK.
[0047]
A cup-shaped nickel electrode 3 having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 4.5 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. Thereafter, the sealing portion was heated with a heater in a non-oxidizing atmosphere and was welded with aluminoborosilicate glass. The length of the glass winding was 2 mm, and the outer diameter was about 2.0 mm.
[0048]
Embodiment 8
Tungsten powder having an average particle size of 2.2 microns, 5 wt% of carbonyl nickel powder having an average particle size of 6 microns, and 3 wt% of carbonyl iron powder having an average particle size of 9 microns were mixed in an attritor. The mixed powder was mixed with a copolymer of ethylene vinyl acetate, butyl methacrylate, and polystyrene, which is an organic binder for injection molding, paraffin wax, butyl phthalate, and stearic acid, and kneaded to obtain a feedstock for metal powder injection molding. . This was put into an injection molding machine, heated to 150 to 160 ° C., and then injection molded in a predetermined mold. The dimensions of the obtained molded body were 1.04 mm in diameter and 3.77 mm in length.
[0049]
The obtained molded body was gradually heated to 700 ° C. in a hydrogen atmosphere, degreased and pre-sintered. Thereafter, sintering was performed at 1400 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 0.8 mm and a length of 2.9 mm. The relative density of the obtained sintered body was 99%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0050]
The coefficient of thermal expansion of the obtained sintered tungsten alloy is 5.6 × 10 ^-6 / K and Kovar were similar, and there was no problem in glass sealing. The specific resistance is 1.4 × 10 ^-5 / Ωcm, the thermal conductivity is 68 W / mK, and the specific resistance of Kovar is 4.9 × 10 ^-5 / Ωcm and thermal conductivity of 17 W / mK.
[0051]
A cup-shaped nickel electrode 3 having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 5 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. The defect rate of resistance welding in the case of using tungsten of the conventional manufacturing method was 0.7%, but in the case of using the present alloy, it decreased to 0.2%. The metal structure of the present sintered tungsten alloy is composed of a matrix composed of a tungsten phase and nickel-iron-tungsten, and therefore has superior resistance weldability to that of pure tungsten. After that, the sealing portion was heated with a heater in a non-oxidizing atmosphere and welded with borosilicate glass. The length of the glass winding was 2 mm, and the outer diameter was about 2 mm.
[0052]
Embodiment 9
Nickel nitrate equivalent to 0.3% by weight of nickel was dissolved in alcohol and added to tungsten powder having an average particle size of 1.5 microns, and after mixing, the alcohol was dried. After drying, nitrate was reduced and removed at 650 ° C. in a hydrogen atmosphere. To this powder, a total of 1.5 wt% of PVA and stearic acid as organic binders for press molding were added together with ethyl alcohol. After the addition, the slurry was spray-granulated with a spray drier to obtain a granulated powder. This granulated powder was press-molded in a predetermined press die. The dimensions of the obtained molded body were 1.0 mm in diameter and 3.37 mm in length.
[0053]
The obtained molded body was gradually heated to 800 ° C. in a hydrogen atmosphere, degreased and pre-sintered. Thereafter, sintering was performed at 1500 ° C. for 1 hour in a hydrogen atmosphere to obtain a sintered body having a diameter of 0.8 mm and a length of 2.7 mm. The relative density of the obtained sintered body was 99.5%. In some cases, the sintered body is subjected to barrel treatment in order to round the corners and to remove burrs during molding and deposits during sintering.
[0054]
The obtained sintered body has a coefficient of thermal expansion of 4.7 × 10 ^-6 / K was almost the same as that of tungsten of the conventional production method, and there was no problem in glass sealing. The specific resistance is 5.9 × 10 ^-5 / Ωcm, the thermal conductivity is 95 W / mK, and the specific resistance of Kovar is 4.9 × 10 ^-5 / Ωcm, and thermal conductivity of 17 W / mK.
[0055]
A cup-shaped nickel electrode 3 having an outer diameter of 1.6 mm, an inner diameter of 1.4 mm and a length of 4.5 mm, and a dimet wire 6 as an external lead wire were resistance-welded to both ends of the obtained sealing rod 4. Thereafter, the sealing portion was heated with a heater in a non-oxidizing atmosphere and was welded with aluminoborosilicate glass. The length of the glass winding was 2 mm, and the outer diameter was about 2.0 mm.
[0056]
【The invention's effect】
As is apparent from the above description, the sintered tungsten alloy, the sintered molybdenum alloy, and the sintered tungsten-molybdenum alloy according to the present invention have a thermal expansion coefficient substantially equal to that of Kovar, tungsten, molybdenum, or the like manufactured by a conventional method. There is no problem in the sealing property.
[0057]
In addition, since the sintering state is not performed through the rolling and drawing steps, cracks and streaks in the longitudinal direction introduced in these steps are not generated. For this reason, the cost of the flaw detection inspection and the visual inspection for the crack check is unnecessary, and the cost can be reduced.
[0058]
Furthermore, since the sintering temperature is lower than conventional methods for manufacturing tungsten rods and molybdenum rods, the structure of the furnace is not only relatively simple, but also the durability of the furnace is improved. Can be. In addition, since the rolling step and the drawing step are not required, the manufacturing cost can be reduced. In addition, an alloy obtained by adding one or more of nickel, iron, cobalt, and copper to tungsten and / or molybdenum contains a phase having a lower melting point than pure tungsten and pure molybdenum. It also has the advantage of excellence.
[0059]
If a convex portion is formed at the end of the sealing rod, reliable melting is ensured during resistance welding, and the reliability of resistance welding is improved. Further, if a concave portion is formed at the end of the sealing rod, it is possible to prevent the burr generated by welding from spreading in the lateral direction, and the glass can be easily wound.
[Brief description of the drawings]
FIG. 1 is a partial sectional view of a discharge lamp.
FIG. 2 is an external view illustrating an example of a sealing rod.
FIG. 3 is an external view showing an embodiment different from the above.
FIG. 4 is a partial sectional view showing still another embodiment.
[Explanation of symbols]
1 Discharge lamp
2 Glass bulb
3 electrodes
4 Enclosure stick
4a convex part
4b recess
5 glass
6 External lead wires

Claims (4)

An encapsulating rod sealed at one end of a glass bulb, one end of which is connected to an electrode portion and the other end of which is connected to an external lead wire, the main component being tungsten and / or molybdenum, nickel, iron, A sealing rod for a discharge lamp, comprising one to two or more of copper and cobalt in a weight ratio of 0.01 to 10%. The discharge lamp sealing rod according to claim 1, wherein a convex portion or a concave portion that is melted during welding is formed at an end portion. 3. The sealing rod for a discharge lamp according to claim 1, wherein nickel is contained in an amount of 0.01 to 7% by weight. The phosphor according to any one of claims 1 to 3, which contains 0.5 to 10% by weight of phosphorus based on the content of one or more of the group consisting of nickel, iron, copper, and cobalt. Sealing rod for discharge lamp.

Images