JP4159048B2 - Assembly, luminous container, assembly for high pressure discharge lamp, and high pressure discharge lamp - Google Patents

Description

  The present invention relates to a joined body, a light emitting container, and an assembly for a high pressure discharge lamp.

  High pressure discharge lamps using quartz discharge tubes have been widely used as automotive headlights due to their brightness and high luminous efficiency. In such a discharge lamp using a quartz tube, since the discharge tube is transparent, the light emitting part by the luminescent gas in the discharge tube can be directly used as a point light source of the discharge lamp.

The present applicant has disclosed in Patent Document 1 that a molybdenum pipe is inserted into openings at both ends of a discharge tube made of translucent translucent alumina, and the pipe and the discharge tube are joined.
JP 2001-76677 A

The discharge lamp of Patent Document 1 is used as a pseudo point light source for automobile headlamps, for example. However, in the field of automobile headlamps and projector lamps, there is also a demand for discharge lamps using transparent discharge tubes.
Patent Document 2 discloses a method of monolithically sealing a sapphire arc tube and a polycrystalline alumina end cap.
Further, Patent Document _{3, Dy 2 O 3 -Al 2} O 3 -SiO 2 based composition for sealing seals the ceramic arc tube for a discharge device is disclosed.
Patent Document 4 discloses a method of hermetically sealing high temperature steam using a Dy ₂ O ₃ —Al ₂ O ₃ -based eutectic cement.
JP-T-2001-519969 JP 56-44025 A U.S. Pat. No. 3,588,573

  In the method described in Patent Document 2, a sapphire arc tube and a polycrystalline alumina end cap are joined by a solid-phase reaction. However, when this inventor examined this conjugate | zygote, it turned out that there exist the following problems. That is, in this method, polycrystalline alumina tends to grow on the contact surface between sapphire and polycrystalline alumina. If this polycrystalline alumina does not grow until it becomes a complete single crystal (sapphire) and grain growth stops before that, coarse alumina particles remain along the bonding interface. As a result, the mechanical strength at the bonding interface is lowered. For this reason, the bonding interface is destroyed by the thermal stress in the region that can be endured. In the vicinity of the contact interface with sapphire, the grain growth control of polycrystalline alumina is very sensitive to firing conditions and is difficult to control.

In the patent document 5, the present inventor described the grain growth and strength reduction when joining a sapphire arc tube and a polycrystalline alumina endcap by solid-phase reaction, for example, at a low temperature of 1730 ° C. or less. Disclosed by heat treatment. However, in this joining method, the joining temperature is relatively low. Considering that corrosive substances inside the high-pressure discharge lamp come into contact with the joint, it is desirable to increase the joint temperature in order to further improve the corrosion resistance of the joint, and in this case as well, It is necessary to be able to suppress cracks.
Japanese Patent Application No. 2003-150512

  An object of the present invention is to increase the bonding strength in a joined body of at least a first member having a joining surface made of sapphire and at least a second member having a joining surface made of sapphire or polycrystalline alumina, and to crack at the joining interface. It is to be able to prevent.

The present invention includes a first member having at least a joining surface made of sapphire, a second member having at least a joining surface made of sapphire or polycrystalline alumina, and a joining material for joining the first member and the second member. The bonding material is made of an oxide containing dysprosium, aluminum, and a second rare earth element other than dysprosium, and the ratio of the second rare earth element in the oxide is 2 mol in terms of oxide. % or more and less 10 mol%, 75 mol% or more ratio of aluminum in oxide in terms of alumina state, and are less 85 mol%, the proportion of dysprosium in the oxide is 10 mol% or more in terms of dysprosium oxide, It is characterized by being 18 mol% or less .

Moreover, this invention is equipped with the said conjugate | zygote, the 1st member is a discharge tube with which the opening was provided in the edge part, and the 2nd member is being fixed to the edge part of a discharge tube. The light-emitting container is a sealing member. The present invention also provides an assembly for a discharge lamp, comprising: the luminous vessel, an electrode provided in an internal space of a discharge tube, and a conductor provided in a sealing member. It is concerned.
Furthermore, the present invention includes the light emitting container, an electrode provided in the inner space of the discharge tube, a conductor provided in the sealing member, and a light emitting substance filled in the light emitting container. The present invention relates to a high-pressure discharge lamp.

  For example, when joining a ceramic discharge tube of a high pressure discharge lamp and a ceramic end cap with a glass joining material, the joining material is easily corroded by the corrosive luminescent gas inside the discharge tube. Higher bonding temperature is better. However, when a bonding material is used, after bonding at a high temperature, the stress due to the difference between the thermal expansion coefficient of the discharge tube material and the thermal expansion coefficient of the end cap greatly contributes to cracking and strength reduction of the bonded portion. It is thought that

  The bonding material used in the present invention melts at a temperature of, for example, 1750 ° C. or higher, typically 1780 ° C. or higher. And although joining in such a comparatively high temperature area | region, it discovered that the crack resulting from the grain growth in a sapphire interface and a joint strength fall could be prevented, and reached this invention.

In the present invention, the bonding material is made of an oxide containing dysprosium, aluminum, and a second rare earth element other than dysprosium, and the ratio of the second rare earth element in the oxide is 2 mol% or more in terms of oxide. 10 mol% or less.
Here, the second rare earth oxide is a kind selected from the group consisting of samarium, scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, europium, gadolinium, terbium, holmium, erbium, thulium, ytterbium and lutetium. Or an oxide of two or more elements. The second rare earth element is preferably Sc ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Ho ₂ O ₃ or Tm ₂ O ₃ , particularly preferably Sc ₂ O ₃ . is there.

  The ratio of the second rare earth element is 2 mol% or more and 10 mol% or less in terms of oxide when the entire bonding material is 100 mol%. If this is less than 2 mol%, cracks due to tensile stress inside the bonding material are likely to occur. Moreover, when this exceeds 10 mol%, the crack resulting from the tensile stress inside a joining material will also be easy to generate | occur | produce.

In a preferred embodiment, the bonding material is a mixture having the following raw material composition.
Dysprosium oxide: 10 mol% or more and 18 mol% or less (particularly preferably 12 mol% or more or 15 mol% or less)
Alumina: 75 mol% or more and 85 mol% or less (particularly preferably 78 mol% or more and 82 mol% or less)
Second rare earth oxide: 2 mol% or more and 10 mol% or less

  In the bonding material of the present invention, the silicon content is preferably 1 mol% or less in terms of oxide, and most preferably contains substantially no silicon. This is because as the silicon content in the bonding material increases, the glass melting temperature during bonding tends to decrease.

  The heat treatment temperature during bonding is preferably 1750 ° C. or higher, and more preferably 1770 ° C. or higher. If the temperature is too high, the members to be joined and cracks in the joining material are likely to occur. Therefore, the heat treatment temperature is preferably 1850 ° C. or less, more preferably 1800 ° C. or less.

  FIG. 1 is a longitudinal sectional view schematically showing a high-pressure discharge lamp 1 and a luminous container 20A according to an embodiment of the present invention. The arc tube 2 includes a pair of openings 2a and 2b and a light emitting section 2f sandwiched between the pair of openings 2a and 2b. Cylindrical sealing members 4A and 4B are joined to the inner openings 2c of the openings 2a and 2b via joining materials 5A and 5B. An ionized luminescent substance and a starting gas are sealed in the inner space 3 of the arc tube 2. In the case of a metal halide high pressure discharge lamp, an inert gas such as argon or xenon and a metal halide are sealed in the internal space of the discharge tube, and mercury or metal zinc is sealed as necessary. Reference numeral 2 d denotes an end face of the arc tube 2. Reference numeral 25 denotes a sealing material.

  The electrode member 6 includes a support portion 6b and a coiled electrode 6a provided at the tip of the support portion 6b. In addition, although the coil 6a was provided in the front-end | tip of the electrode member 6 in this example, the coil 6a is not necessarily required.

  In this example, a raw material for the bonding materials 5A and 5B is interposed between the discharge tube 2 as the first member and the sealing members 4A and 4B as the second member, and this raw material is heat-treated. The first member and the second member are joined. The bonding material is made of an oxide containing dysprosium, aluminum, and a second rare earth element other than dysprosium, and the ratio of the second rare earth element in the oxide is 2 mol% or more and 10 mol% or less in terms of oxide. . Further, the angle formed by the c-axis (arrow C) of sapphire constituting the discharge tube 2 and the tube axis L of the discharge tube 2 is 10 ° or less.

  The form of the discharge tube and the sealing member is not particularly limited, and for example, it may have a form as shown in FIGS. In the discharge lamp 11 and the luminous vessel 20B of FIG. 2, the discharge tube 2A and the end sealing member 14 are joined. The end sealing member 14 of this example includes a flat plate portion 14a, an annular flange portion 14b protruding from the edge of the flat plate portion 14a, and an electrode holding portion 14e protruding from the center of the flat plate portion 14a. Yes. An electrode member 16 is inserted into a through hole 14a inside the electrode holding portion 14e, and an electrode 16a is provided at the tip thereof.

  The joining surface 14c of the flat plate-like portion 14a of the sealing member 14 is joined to the end surface 2d of the discharge tube 2A by the joining material 15. Further, the flange portion 14b of the sealing member 14 is bonded to the end outer surface 2e of the discharge tube 2A by the bonding material 15.

  In the discharge lamp 21 and the luminous container 20C of FIG. 3, the discharge tube 2A and the end sealing member 24 are joined. An annular groove 24b is formed in the flat plate portion 24a of the end sealing member 24 of this example, and an electrode holding portion 24c protrudes on the opposite side. The electrode member 16 is inserted into the through hole 24f inside the electrode holding portion 24c, and the electrode 16a is provided at the tip thereof.

  The end 2a of the discharge tube 2A is inserted into the groove 24b. The end surface 2d, the inner side surface 2c, and the outer side surface 2e of the discharge tube 2A are bonded to the inner wall surface of the groove 24b of the sealing member 24 by the bonding material 15A.

  In the example of FIGS. 2 and 3, the raw material for the bonding material 15, 15 </ b> A is interposed between the discharge tube 2 </ b> A as the first member and the sealing members 14, 24 as the second member. The first member and the second member are joined by heat-treating. The bonding materials 15 and 15A are made of an oxide containing dysprosium, aluminum, and a second rare earth element other than dysprosium, and the ratio of the second rare earth element in the oxide is 2 mol% or more in terms of oxide, It is 10 mol% or less. The angle formed by the c-axis (arrow C) of sapphire constituting the discharge tube 2A and the tube axis L of the discharge tube 2A is 10 ° or less.

  By aligning the c-axis of the discharge tube made of sapphire in substantially the same direction as the tube axis (center axis) of the discharge tube, in the vicinity of the interface between the discharge tube and the second member fixed to the end of the discharge tube The sapphire cracking rate can be significantly reduced. From this viewpoint, it is more preferable that the angle formed by the c-axis of sapphire constituting the discharge tube and the tube axis of the discharge tube be 5 ° or less.

  In any example, an ionized luminescent substance and a starting gas are sealed in the inner space 3 of the arc tube. In the case of a metal halide high pressure discharge lamp, an inert gas such as argon or xenon and a metal halide are sealed in the internal space of the discharge tube, and mercury or metal zinc is sealed as necessary.

  The material of the discharge electrode is not limited, but a pure metal selected from the group consisting of tungsten, molybdenum, niobium, rhenium and tantalum is preferable, or two types selected from the group consisting of tungsten, molybdenum, niobium, rhenium and tantalum Alloys of the above metals are preferred. A composite material of these pure metals or alloys and ceramics is preferable.

  The high-pressure discharge lamp of the present invention can be applied to various lighting devices such as an automotive headlamp, an overhead projector (OHP), and a liquid crystal projector.

  In addition to the high-pressure discharge lamp, the joined body of the present invention can be widely applied as a part of a structure having a conductive portion or a terminal that requires airtightness at high temperatures of 900 ° C. or higher, such as a switch such as a vacuum. it can. Moreover, it can be used suitably for the use exposed to corrosive gas, especially halogen type corrosive gas.

(Experiment A)
An assembly for a high-pressure discharge lamp and a luminous container as shown in FIG. 1 were produced. However, the discharge tube 2 and the sealing members 4A and 4B were formed of sapphire. The electrode member 6 was made of molybdenum.

A mixture of each powder of dysprosium oxide, alumina, and scandium oxide was weighed. The ratio is shown in Table 1 (mol% unit).
Each mixture was molded to obtain a ring-shaped molded body, which was degreased at 700 ° C. in the atmosphere. The obtained ring-shaped molded body was set at the position of the bonding materials 5A and 5B in FIG. 1, treated by heat treatment in a dry non-oxidizing atmosphere, and then cooled. The heat treatment temperature is 1780 ° C.

  Each of the obtained light emitting containers was examined for the presence or absence of cracks during cutting. Specifically, the joint was sliced on a plane parallel to the tube axis L in FIG. 1, and the presence or absence of cracks extending in an arc shape was observed on this cut surface. Twenty samples were prepared for each example, and the percentage ratio of the number of samples in which cracks were observed to the total number is shown in Table 1. A crack at the time of cutting occurs when a tensile stress of a certain level or more is generated in the bonding material of the bonding portion in the radial direction.

  As can be seen from the results in Table 1, when the ratio of scandium oxide is 2 to 10 mol%, no cracking occurs at the time of cutting despite the high heat treatment temperature at 1780 ° C. during bonding.

  As described above, according to the present invention, in the joined body of the first member having at least the joining surface made of sapphire and the second member having at least the joining surface made of sapphire or polycrystalline alumina, the crack in the joining portion is formed. It is possible to provide a joined body in which the above is prevented.

It is a longitudinal cross-sectional view which shows typically the assembly 1 for high pressure discharge lamps and luminous container 20A which concern on one Embodiment of this invention. It is a longitudinal cross-sectional view which shows typically the assembly 11 for high pressure discharge lamps and luminous container 20B which concern on other embodiment of this invention. It is a longitudinal cross-sectional view which shows typically the assembly 21 for high pressure discharge lamps and 20 C of light emission containers which concern on other embodiment of this invention.

Explanation of symbols

  1, 11, 21 High pressure discharge lamp 2, 2A Discharge tube 2a, 2b Discharge tube end 2c End inner wall surface 2d End surface 2f Light emitting portion 4A, 4B, 14, 24 Sealing member 5A, 5B, 15A, 15B Bonding material 6 , 16 Electrode device C C axis of sapphire L Tube axis

Claims (6)

A first member having at least a joining surface made of sapphire, a second member having at least a joining surface made of sapphire or polycrystalline alumina, and a joining material for joining the first member and the second member. A joined body,
The bonding material is made of an oxide containing dysprosium, aluminum, and a second rare earth element other than dysprosium, and the ratio of the second rare earth element in the oxide is 2 mol% or more and 10 mol% in terms of oxide. or less, wherein the ratio of aluminum in the oxide is 75 mol% or more in terms of alumina state, and are less 85 mol%, the proportion of dysprosium in the oxide converted to 10 mol% or more of dysprosium oxide, below 18 mol% A joined body characterized by being.   The joined body according to claim 1, wherein the second rare earth element is scandium. The joined body according to claim 1 or 2 , wherein the first member is a discharge tube having an opening at an end, and the second member is fixed to an end of the discharge tube. A light emitting container, which is a sealed member. The light emitting container according to claim 3 , wherein an angle formed by a c-axis of sapphire constituting the discharge tube and a tube axis of the discharge tube is 10 ° or less. Characterized in that it comprises a claim 3 or 4 light emitting vessel, wherein the electrode is provided in the inner space of the discharge tube, and the conductor provided in the sealing member, a high pressure discharge lamp Assembly body. Luminous container of claim 3 or 4, further comprising the electrodes provided in the inner space of the discharge tube, conductor provided in the sealing member, and a light-emitting substance that is filled into the light emitting vessel A high-pressure discharge lamp characterized by

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