JP2000182566A - Bulb provided with sealing body of gradient functional material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the lifetime of bulb while preventing the generation of contact failure at a power supplying part and breakdown of a bonding part to a blocking body by providing an acid resistant layer in a constant area of a metal external lead directed outward from an end surface of a blocking body provided in the bulb and made of the gradient functional material having a nonconductive end and a conductive end. SOLUTION: One end of a sealing body 23 is conductive including molybdenum component, and silica component is increased as it comes close to the other end so as to be nonconductive. The nonconductive end surface is arranged so as to face to a discharge space, and welded to a side tube 11 by a burner in the nonconductive area including molybdenum less than 2 vol.% of content. An electrode core rod 26 is integrally formed while having an internal lead part 22 extended from an electrode 21 to the sealing body 23 and an external lead part 24 projected and extended from the outer end surface of the sealing body 23, and the electrode core rod 26 is fixed by burning for fastening in the conductive area of the sealing body 23 through the center hole of the sealing body 23. A surface of the external lead part 24 is provided with an acid resistant layer 30 in an area having probability of oxidization of the external lead part 24 from the sealing body 23 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulb closed using a closure made of a functionally graded material.

[0002]

2. Description of the Related Art Recently, a material using a functionally gradient material for an occlusion body of a tube has been proposed and used. The closed body is configured such that the non-conductive component and the conductive component change continuously or stepwise so that one is rich in the non-conductive component and the other is rich in the conductive component toward the other. An assembly in which a member such as an electrode core for power supply is fixed to such an obstructing body by baking in the high-concentration region of the conductive component of the obstructing body is constituted, and an end-end power supply structure of the bulb and an airtight sealing structure are formed. When used, the length of a portion required for a sealing portion (a power supply portion or a hermetic sealing portion) can be reduced as compared with a conventional tube, so that the entire length of the tube can be shortened. It is.

[0003]

However, a tube provided with the above-described closure made of a functionally graded material is a power supply member (hereinafter referred to as an "external lead portion") exposed to the outside from the closure.
That. In particular, oxidation may occur in the metal component on the closed body side, and if the lamp is continuously lit, a problem arises in that the lamp is not lit.

[0004] The present inventors have studied this problem, and, contrary to the advantage that the length of the sealed portion of the bulb can be shortened by forming the closing body with a functionally gradient material, use of a functionally gradient material is not possible. The present inventors have found that the external lead portion is heated to an unexpectedly high temperature because the external lead portion is disposed very close to the light source (or heat source) side as compared with a tube not provided. As a material for the external lead portion, for example, tungsten (W) is preferably used, and the temperature at which this tungsten reaches oxidation is said to be about 350 ° C. No oxidation was observed in the outer lead portion of the conventional bulb, but it was found that the outer lead portion could be heated to a temperature of 500 ° C. or more in the case of a tube using a functionally graded material closure. did.

When the external lead portion is exposed to the above-mentioned high temperature in the atmosphere, the metal component is oxidized, and a poor electrical contact occurs at the site,
Alternatively, the joining portion between the external lead portion and the closing body (specifically,
It has been found that the high concentration side of the conductive component of the closed body is damaged and a leak occurs in the hermetically sealed portion, and as a result, the lamp is not lit.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to prevent oxidation of an external lead portion in a bulb having a functionally-graded material closing body, and to provide an electrical connection at a power supply site. It is an object of the present invention to provide a bulb having a long service life, which prevents poor contact and breakage at a joint portion with a closed body and does not cause a problem such as early non-lighting of the bulb.

[0007]

According to a first aspect of the present invention, a non-conductive material and a conductive material are mixed continuously or stepwise at different ratios in the longitudinal direction to make one end non-conductive. A functionally graded material whose end side is conductive is provided on the bulb to form a closed body,
An outer tube is provided with a metal external lead portion protruding outward from the closing body. In the bulb, an oxidation-resistant layer is provided on a surface of the outer lead portion over a predetermined region outward from an end surface of the closing body. It is characterized by having.

In a second aspect of the present invention, the external lead portion is made of tungsten (W) or molybdenum (Mo), and the oxidation-resistant layer is made of borosilicate containing Na ₂ O.B ₂ O ₃ .SiO ₂ as a main component. It is characterized by being glass.

Further, in the third invention of the present application, the oxidation-resistant layer is formed of a metal component constituting the external lead portion and silicon (S).
and i) is a compound containing as a main component.
Still further, in the fourth invention of the present application, the metal component and silicon (S
i) SiO ₂ and / or a compound mainly composed of SiO ₂ is formed on the surface of the oxidation-resistant layer composed of a compound mainly composed of i).

[0010]

According to the tube (hereinafter, also simply referred to as "tube") having the functionally graded material closing body according to the first invention of the present application, the metal external lead portion is covered with the oxidation-resistant layer. Therefore, even if the external lead becomes extremely hot,
The metal component does not cause an oxidation reaction, and can prevent poor electrical contact at the external lead portion and breakage at a joint portion with the closing member, thereby preventing non-lighting of the bulb.

According to the second aspect of the present invention, as the material of the external lead portion, tungsten (W) or molybdenum (Mo), which is a high melting point metal, can be preferably used, and Na ₂ O.B is used as the oxidation-resistant layer. _{When a} combination of borosilicate glass containing ₂ O ₃ · SiO ₂ as a main component is applied, the air can be shut off at the external lead portion and oxidation of the metal component can be prevented. By using this borosilicate glass, even at high temperatures, the difference in the coefficient of linear expansion from tungsten or molybdenum can be reduced to prevent the occurrence of cracks, so that a stable oxidation-resistant layer can be obtained.

According to the third aspect of the present invention, if the oxidation-resistant layer is composed of the metal component of the external lead portion and a compound containing silicon (Si) as a main component, the compound is formed earlier than the metal component of the external lead portion. By bonding with oxygen, SiO ₂ is formed on the surface. Since this SiO ₂ blocks the atmosphere, oxygen permeation is prevented, so that no oxygen is supplied to the metal component of the external lead portion, so that oxidation can be prevented in the external lead portion.

According to a fourth aspect of the present invention, the metal and silicon (Si) as main components have SiO ₂ and / or a compound having SiO ₂ as the main component formed on the surface thereof. And a compound mainly containing silicon (Si) are shielded from the atmosphere, so that the function as an oxidation-resistant layer is improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is an explanatory sectional view showing an embodiment of a tube according to the present invention. A discharge lamp having a bulb according to the present invention includes an arc tube 10 having side tubes 11 extending at both ends of a discharge space, an electrode 21 arranged to face substantially the center of the discharge space, and an open end of the side tube 11. In the arc tube 1
And a closing member 23 that closes 0.

The closing member 23 is substantially cylindrical and made of a functionally gradient material composed of molybdenum as a conductive component and silica as a non-conductive component. In other words, the closing body 23 is conductive at one end, rich in molybdenum component, the silica component increases continuously or stepwise toward the other end, the composition changes, and the other end is rich in silica component. Non-conductive.

The non-conductive side end face of the plug 23, which is rich in silica component, is disposed so as to face the discharge space, and the end of the plug 23 on the silica side, preferably containing a conductive component (molybdenum). In a region where the amount is less than 2 vol%, the side tube 11 is welded to the side tube 11 by a burner.

The electrode core bar 26 extends from the electrode 21 to the closing member 23 in the discharge space.
And an external lead portion 24 protruding from the outer end surface of the closing body 23 and extending outward. Then, the electrode core rod 26 is inserted into a through hole provided substantially at the center of the closing body 23, and is fixed by being shrunk in the conductive region (molybdenum side) of the closing body 23. Note that the inner lead portion 22 and the outer lead portion 24 are not integrally formed, but may be formed of different members. In such a case, the current is supplied through the conductive region of the closed body 23 that constitutes the functionally gradient material.

An oxidation-resistant layer 30 is provided on the surface of the external lead portion 24 from the outer end face of the closing body 23 to the outside thereof. Particularly, the region where the oxidation-resistant layer 30 is provided is as follows.
This is a region where at least the external lead portion 24 may be oxidized from the closed body 23 side of the external lead portion 24.

[Embodiment 1] FIG. 1 shows a 2 kW embodiment 1
3 is a schematic view of the xenon lamp of FIG. _TwoO ・
B_TwoO_Three・ SiO_TwoConsisting of borosilicate glass whose main component is
This is an example. Closures 23 located at both ends of arc tube 10
Is made of functionally graded material consisting of silica and molybdenum,
The light-emitting part side is the high concentration side of silica (non-conductive side) and the opposite outer end
The side is the molybdenum high concentration side (conductive side). Closure 2
3 has an outer diameter of 16 mm and a total length of 50 mm.
Is a tungsten electrode core rod 26 with an outer diameter of 4 mm.
And they are fastened and fixed at the joint between them.
You.

FIG. 2 shows an electrode assembly 20 including an electrode 21, an electrode core 26, and a closing body 23. As shown in the figure, the oxidation-resistant layer 3
The electrode assembly 20 is connected to the arc tube 10 in a state where 0 is provided.

In this embodiment, a borosilicate glass containing Na ₂ O.B ₂ O ₃ .SiO ₂ as a main component is used as the oxidation-resistant layer 30 of the external lead portion 24.

The method of coating the outer lead portion 24 with the oxidation-resistant layer 30 will be described in detail below. Na ₂ O ・ B ₂ O
_3. The bulk material of the SiO ₂ -based glass is roughly pulverized, and when it becomes a coarse powder, a solvent is added and pulverized by a ball mill.
When the glass is further pulverized and mixed well with a solvent, a glass in a slurry state is obtained. This slurry-like glass is applied evenly to the closed body 23 side of the external lead portion 24. As the portion to be applied to the external lead portion 24, specifically, the closing body 2
3 is a portion having a length of 20 mm outward from the end face. After the slurry-like glass has dried, the holding heated to 1000 ° C. The electrode assembly 20 of the outer lead portion 24 and the closure 23 in a hydrogen atmosphere for 10 min, Na ₂ O ·
An oxidation resistant layer 30 made of B ₂ O ₃ .SiO ₂ glass is obtained. Note that the heat treatment can be performed even in an inert gas atmosphere.

In the first embodiment, since the linear expansion coefficient of tungsten is 46 × 10 ⁻⁷ [K ⁻¹ ], Na ₂ O having a similar linear expansion coefficient of 38 × 10 ⁻⁷ [K ⁻¹ ] is used.・ B ₂ O ₃・ S
iO ₂ glass was used.

Next, an oxidation-resistant layer (Na ₂ O.B ₂ O ₃ .S
An example in which borosilicate glass containing iO ₂ as a main component is provided on the external lead portion 24 by a method different from the above method will be described. First, a glass tube mainly composed of Na ₂ O.B ₂ O ₃ .SiO ₂ is prepared. The inner diameter of the glass tube is slightly larger than the outer diameter of the external lead portion 24, and in this embodiment, the inner diameter is 4.
05mm, outer diameter 5mm
mm. Since the region to be the oxidation-resistant layer 30 varies depending on the type and size of the tube used, the tube is appropriately cut to a desired length. Next, the external lead portion 24 is inserted into the cylindrical hole of the glass tube so that one end surface of the glass tube is brought into contact with the end surface of the closing member 23, and the one end is placed in a hydrogen atmosphere.
Heated to 000 ° C. and held for about 10 minutes. As a result, the glass tube is melted and hermetically welded to the outer surface of the external lead portion 24 to form the oxidation-resistant layer 30. Note that the heat treatment may be performed in an inert gas atmosphere.

[Embodiment 2] A second embodiment will be described. FIG. 3 is an explanatory cross-sectional view of a tube explaining the present embodiment,
One end of a halogen lamp with a fixed power consumption of 500 W is shown. Closing bodies 23 made of a functionally gradient material are welded to both ends of the arc tube 10. The arc tube 10 has a diameter of 10 mm,
It consists of a glass tube made of silica glass (quartz glass) with an inner diameter of 8 mm. Halogen lamp filament emission length is about 1
27 mm.

The closing member 23 is made of a functionally graded material in which molybdenum as a conductive substance and silica as a non-conductive substance have a gradually changing concentration in the axial direction. It has a substantially cylindrical shape of 20 mm. The closing body 23 has a non-conductive side rich in silica concentration directed toward the light emitting unit side.
Are buried to the position where the molybdenum concentration is 40 vol% and are fired. On the other hand, on the other end surface of the closing body 23, an external lead portion 24 is inserted into a hole provided at a substantially central portion and is heat-sealed.

An electrode assembly 20 comprising an internal lead 22, a closing member 23 and an external lead 24 was prepared, and an oxidation-resistant layer 30 was provided on the external lead 24. Na ₂ O ・ B ₂
The surface of the external lead portion 24 was coated with an oxidation-resistant layer 30 in the same manner as in Example 1 using borosilicate glass containing O ₃ · SiO ₂ as a main component. That is, the Na ₂ O.B ₂ O _3.
A mixed slurry of SiO ₂ glass and a solvent was prepared, and the slurry was applied to a region of about 10 mm outward from the end face of the closing body 23 of the external lead portion 24. Thereafter, after the slurry was dried, the electrode assembly 20 was heated in a hydrogen atmosphere. The temperature and time at this time are the same as those in the first embodiment. Further, this heat treatment step may be performed in an inert gas atmosphere.

As described above, after coating the outer lead portion 24 with the oxidation-resistant layer 30, the filament coil 25 is connected to the end of the inner lead portion 22 on the light emitting portion side, inserted into the light emitting tube 10, and inserted into the light emitting tube. The inner peripheral surface of the tube 10 and the outer peripheral surface of the closing body 23 were welded and sealed.

In the first and second embodiments, the external leads may be made of molybdenum (Mo) in addition to tungsten (W). In the case when the external lead section is made of molybdenum (Mo) according, when using a _{Na 2 O · B 2 O 3} · SiO 2 based glass oxidation layer, the linear expansion coefficient of molybdenum 49 × 10 ^-7 [ K ^-1 ]
Therefore, the linear expansion coefficient is 47 × 10
^-7 [K ^-1 ], the above Examples 1 and 2
A suitable oxidation-resistant layer can be obtained in the same manner as described above.

Third Embodiment Next, a xenon lamp according to a third embodiment will be described. The basic structure of the third embodiment is the same as that of the first embodiment, and the drawings will be described with reference to FIG. 1 and using the same reference numerals. The closing body 23 is made of a functionally gradient material composed of silica and molybdenum. The light emitting portion side is a high-concentration side of silica (non-conductive side), the outer end side is a high-concentration side of molybdenum (conductive side), and the outer diameter is about 16 mm. It has a substantially cylindrical shape of 50 mm. After provisionally sintering the closing member 23, a 4 mm-diameter tungsten rod for the electrode core 26 was inserted into the center of the closing member 23 to form the electrode assembly 20.

A slurry of silicon (Si) powder was applied to the external lead portion 24 over a region extending outward from the rear end surface of the closing member 23, specifically, over a width of about 20 mm. This slurry was prepared by mixing silicon (Si) powder having an average particle size of about 50 μm with nitrocellulose as a binder material. After drying the slurry, the electrode assembly was cooled to 1700-1730 ° C. in a vacuum of 10 ⁻³ Pa or less.
For about 10 minutes to perform main sintering of the closing body 23. During this sintering step, a compound composed of tungsten (W) and silicon (Si) is formed on the surface of the external lead portion 24 (hereinafter, also simply referred to as “W-Si-based compound”). The W-Si compound is silicon (Si)
Of 40 to 67 atomic%.

Here, the function of the W-Si compound will be described. Before using the lamp, W-
An Si-based compound is formed. Since this W-Si compound is a compound that easily bonds with oxygen (O ₂ ) under the same atmosphere as tungsten (W) under the same atmosphere (that is, it shows oxidizability), for example, by using a lamp for lighting,
When exposed to a high temperature in the air, the W-Si-based compound combines with oxygen (O ₂ ) prior to tungsten (W) in the external lead portion to form SiO ₂ . This SiO
₂ blocks the external lead portion from the atmosphere to prevent the permeation of oxygen, and consequently functions as an oxidation-resistant layer.

In the present invention, the final substance that contributes to the oxidation resistance is SiO ₂ , and it is thought that the W—Si compound alone does not directly contribute to the oxidation resistance. SiO ₂ from atmospheric oxygen
Is generated to obtain oxidation resistance. Therefore W
-SiO ₂ type compounds are found to be compound that contributes to oxidation. Therefore, in the present invention, "W-Si based compound" is referred to as "oxidation resistant layer".

In this embodiment, the external lead 2
Although tungsten (W) is used as the material of No. 4, other high melting point metals may be used. For example, molybdenum (M
o), tantalum (Ta), niobium (Nb) and the like. For example, when the external lead portion 24 is made of molybdenum (Mo), a Mo—Si-based compound (for example, containing 25 atomic% or more of Si) may be formed on the surface of the external lead portion 24. This Mo—Si-based compound also has a higher oxidizability than molybdenum (Mo) and is bonded to oxygen (O ₂ ) before molybdenum (Mo), so that SiO ₂ is formed on the surface. As a result, the permeation of oxygen (O ₂ ) is prevented, and oxygen (O ₂ ) is not supplied to the molybdenum (Mo) at the site, thereby preventing the external leads from being oxidized.

As described above, the metal component and the compound containing silicon (Si) as main components constituting the external lead portion formed on the surface of the external lead portion are heated to a high temperature by, for example, lighting operation. Since the metal component is more easily oxidized than the external lead portion, it binds to oxygen before the metal component at the site, and SiO ₂ is formed on the surface. Oxidation resistance in the lead portion is achieved. As a result, oxidation can be prevented at the external lead portion, and poor electrical contact at the external lead portion (especially in the vicinity of the closing member) and damage at a joint portion with the closing member can be prevented. It is possible to form a bulb having a long service life without generation.

In the tube of this example, metal and silicon (SiO
_The compound mainly composed of ₂ ) first binds to oxygen (O ₂ ), that is, the compound itself is oxidized, so that Si in the compound forms SiO ₂ to the metal component of the external lead portion. Since the supply of oxygen is cut off, a function as an oxidation-resistant layer is achieved.

As the firing conditions for forming the above-described oxidation-resistant layer, that is, a compound containing metal and silicon as main components, it is desirable to heat at a pressure of 10 ⁻² Pa or less and a temperature of 1000 ° C. or more. According to the firing conditions, a compound comprising a metal and silicon can be stably generated.

Further, if the above-mentioned firing step is performed simultaneously with the main sintering of the closed body as in the third embodiment, the time can be reduced and energy can be saved, and the productivity of the closed body is improved. In addition, cost reduction can be realized.

Next, an embodiment of the fourth invention of the present application will be described. In the present invention, SiO ₂ and / or a compound containing SiO ₂ as a main component is formed on the surface of the oxidation-resistant layer according to the third invention of the present application (that is, a compound containing metal and silicon as main components). By doing so, the function as the oxidation-resistant layer can be maintained for an extremely long time.

As the SiO ₂ and / or the compound containing SiO ₂ as a main component of the present invention, for example, silica (SiO ₂ )
Na ₂ O.B ₂ O ₃ .S mainly composed of glass or silica
iO ₂ based glass can be preferably employed.

The compound containing SiO ₂ as a main component is S
SiO the iO ₂ powder nitrocellulose as a binder ₂
A powder slurry is prepared, applied from above the oxidation-resistant layer, and fired in a vacuum to form the slurry. In particular,
In the third embodiment, the slurry of the Si powder is applied to a predetermined region of the external lead portion, and then the SiO ₂ powder slurry according to the present invention is applied repeatedly, and the slurry is dried and then fired.

As described above, the surface of the oxidation resistant layer is
Due to the formation of the iO ₂ -based compound, the oxidation-resistant layer (that is, the compound containing metal and silicon as main components)
And the atmosphere are preferably blocked, and such compounds are also less likely to bind to oxygen. Therefore, the metal component constituting the external lead portion is harder to be oxidized, and the service life of the bulb can be prolonged.

The present invention is not limited to the first to third embodiments, and the oxidation-resistant layer may be formed by coating the external lead portion with a noble metal such as platinum (Pt) or rhodium (Rh).

The constituent components of the functionally graded material used as the closing member are not limited to the combination of molybdenum and silica, and molybdenum (Mo), tungsten (W), platinum (Pt), nickel (Ni) are used as conductive materials. , Tantalum (Ta), zirconium (Zr), etc. can be applied, and non-conductive materials include aluminum oxide (Al ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), and magnesium oxide (Mg).
O), calcium oxide (CaO), zirconium oxide (ZrO ₂ ), and the like.

The lamp is not limited to a discharge lamp or a halogen lamp, and may be applied to an infrared heater in which a heating element is sealed in a silica glass tube. Further, the AC type and the DC type are not limited. The present invention is not limited to a xenon lamp, but may be applied to a mercury lamp, a metal halide lamp, or the like.

[Thermal Oxidation Test 1] An oxidation resistance test was performed on the external lead portion provided with an oxidation resistant layer to examine its effect. The [Sample 1] tungsten rod having an outer diameter of 2mm for outer lead portion as a sample piece was coated with _{Na 2 O · B 2 O 3} · SiO 2 -based glass. The coating method is the same as the method described in the first embodiment. That is, Na ₂ O.B ₂ O ₃ .Si
A method of applying a slurry of an O ₂ -based glass to a tungsten rod, followed by drying and heat treatment in a hydrogen atmosphere or an inert gas. The condition of the heat treatment was 1000 ° C. for 10 minutes. Further, a glass tube having an outer diameter of 3 mm and an inner diameter of 2.05 mm is cut into 10 mm, and a tungsten rod having an outer diameter of 2 mm is inserted into a cylindrical hole of the glass tube, and the tube is placed in a hydrogen atmosphere.
It was kept at 00 ° C. for 10 minutes to provide an oxidation-resistant layer.

Ten specimens each having an oxidation-resistant layer provided on a tungsten rod and ten specimens each having no oxidation-resistant layer prepared as a comparative sample are expected to be the maximum use temperature of the external lead portion when the lamp is turned on. (Temperature that can be reached by the external lead portion of the heater lamp)
After holding for a time, an oxidation resistance test was performed.

As a result of visually observing the sample piece and evaluating the oxidation state of the tungsten rod, no sign of oxidation was observed in the portion of the sample piece covered with the oxidation-resistant layer, leaving the state of metallic tungsten. In addition, Na ₂ O · B ₂ O ₃
No cracks or cracks were observed in the SiO ₂ -based borosilicate glass. On the other hand, it was confirmed that yellow to yellow-green tungsten oxide (tungsten trioxide, WO ₃ ) was generated in the entire area of the sample piece where the oxidation-resistant layer was not applied.

Accordingly, it has been confirmed that by providing an oxidation-resistant layer on the external lead portion of the electrode core rod, the oxidation of the external lead portion can be preferably prevented without oxidizing the metal component constituting the external lead portion. And N
_{a 2 O · B 2 O 3} · SiO 2 -based glass was found to be a suitable material for the oxidation-resistant layer.

[Oxidation Resistance Test 2] An electrode assembly having a W-Si-based compound formed on the surface of a tungsten rod was manufactured and subjected to a life test. An electrode assembly composed of a closed body and an electrode core (or an external lead portion) was prepared in the same manner as in Example 3 to obtain Sample 2, and an electrode assembly without an oxidation-resistant layer was prepared for comparative study. And used as a comparative sample. A method for manufacturing an electrode assembly as Sample 2 is described below. [Sample 2] An electrode assembly for a discharge lamp was prepared as follows. First, an electrode rod made of tungsten having an outer diameter of 4 mm was inserted through a temporary sintered body of a substantially cylindrical functionally graded material having an outer diameter of 16 mm and a total length of 50 mm. Slurry is applied and SiO
A slurry of the _two powders was applied, and after the slurry was dried, it was heated to about 1700 ° C. in a vacuum (10 ⁻³ Pa or less) and held for 10 minutes to produce an electrode assembly. Further, an electrode assembly for an incandescent lamp was produced as follows. A tungsten rod having an outer diameter of 2 mm is inserted as an external lead into a pre-sintered body of a substantially cylindrical functionally graded material having an outer diameter of 7 mm and a total length of 20 mm, and a slurry of Si powder is applied to the surface of the outer lead, Further, a slurry of SiO ₂ powder is applied thereon and dried, and then dried at 1700 ° C. in vacuum (10 ⁻³ Pa or less)
After heating and holding for 10 minutes, an electrode assembly was produced.

In the life test, the sample 2 and the comparative sample were kept at 500 ° C. and 600 ° C. in the air, and the external lead portion was oxidized to cause a break at the joint with the closing member. The time until the leak occurred was measured as the service life. 5 samples each
The average value of the service life (hour) was determined using each of the books. Table 1
The results are shown in FIG.

[0052]

[Table 1]

The external lead rod of Sample 2 did not oxidize and showed good oxidation resistance. As shown in Table 1, it was confirmed that the service life of the electrode assembly was extremely long.

[0054]

As described above, in a tube provided with an obstruction made of a functionally graded material, an oxidation-resistant layer is provided on the surface of the external lead portion over a certain area outward from the end face of the obstruction. By doing so, it is possible to avoid oxidation of the external lead, prevent poor electrical contact at the external lead and damage at the joint with the closed body, and turn off the lamp early. Thus, it is possible to provide a long-life tube that does not cause any troubles such as failure.

When the external lead portion of the electrode rod is made of tungsten or molybdenum, the oxidation-resistant layer is
It is preferable to use borosilicate glass containing Na ₂ O.B ₂ O ₃ .SiO ₂ as a main component.

The metal component and the compound containing silicon (Si) as main components constituting the external lead portion formed on the surface of the external lead portion are combined with oxygen before the external lead portion to form SiO 2 on the surface. To form
This SiO ₂ cuts off the supply of oxidation to the metal component at the site, thereby preventing oxidation at the external lead portion. As a result, it is possible to prevent poor electrical contact at the external lead portion (especially, in the vicinity of the closing member) and damage at a joint portion with the closing member, thereby preventing a lamp from being turned off early and having a long service life. It can be.

Further, SiO ₂ and / or a compound containing SiO ₂ as a main component is further formed on the surface of the above-mentioned compound containing a metal and silicon as main components. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a xenon lamp showing an example of a tube provided with a closure made of a functionally gradient material according to the present invention.

FIG. 2 is an enlarged view of an electrode assembly including an electrode, an electrode rod, and a closing body.

FIG. 3 is a halogen lamp showing another example of a bulb provided with a blocker made of a functionally gradient material according to the present invention.

DESCRIPTION OF SYMBOLS 10 Arc tube 11 Side tube 20 Electrode assembly 21 Electrode 22 Internal lead part 23 Closure body 24 External lead part 25 Filament 26 Electrode core rod 30 Oxidation-resistant layer

Claims (4)

[Claims] A non-conductive material and a conductive material are continuously or stepwise mixed at different ratios in a length direction to form a functionally graded material having one end non-conductive and the other end conductive. A closed body provided on a bulb, and a metal external lead portion protruding outwardly provided on the closed body. In a tube, a surface of the external lead portion is directed outward from an end face of the closed body. A bulb comprising a closure made of a functionally graded material, characterized in that an oxidation-resistant layer is provided over the region. 2. The method according to claim 1, wherein the external lead portion is made of tungsten (W).
Or consists of molybdenum (Mo), the oxidation-resistant layer is _{Na 2 O · B 2 O 3} · FGM made closure according to SiO ₂ in claim 1, characterized in that the borosilicate glass as a main component A tube with a body. 3. The obstruction made of a functionally graded material according to claim 1, wherein the oxidation-resistant layer is a compound mainly composed of a metal component and silicon (Si) constituting the external lead portion. A tube with a body. 4. The method according to claim 1, wherein the surface of the oxidation-resistant layer has SiO ₂ and / or
4. A bulb having a functionally graded material closure according to claim 3, wherein a compound mainly composed of SiO ₂ is formed.