JP2009016211A - Electrode assembly, manufacturing method thereof, and discharging tube using same electrode assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode assembly wherein the leakage of a discharging gas is suppressed, and an electrode comprising a metal sintered body containing a refractory metal and a lead wire comprising the refractory metal are welded to each other with a high mechanical strength. <P>SOLUTION: The electrode assembly (4) has an electrode (1) comprising a metal sintered body, a lead wire (2) joined to a bottom portion (1a) of the electrode (1), and a fillet portion (3) provided in the periphery of the joining portion of the electrode (1) to the lead wire (2) and for joining the electrode (1) to the lead wire (2). The electrode (1) contains refractory tungsten particles (W) dispersed in the base material of the metal sintered body and contains a nickel powder (Ni) having a lower melting point than that of the tungsten particles (W) which adheres intimately to the tungsten particles (W) as the carrying material of the tungsten particles (W). The lead wire (2) is made of the same metal as the tungsten particles (W). The fillet portion (3) has a metal organizing structure wherein tungsten particles (W) comprising the same metal as the tungsten particles (W) of the electrode (1) are dispersed in a base material comprising the same metal as the nickel powder (Ni) contained inside the electrode (1). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrode assembly in which a lead wire is welded to the bottom of a sintered electrode, a method for manufacturing the electrode assembly, and a discharge tube having the electrode assembly.

  For example, in a discharge tube such as a cold cathode fluorescent discharge tube (CCFL), the electrode generates heat due to the discharge during lighting. In order to enhance the durability of the discharge tube against thermal shock caused by the heat generated by the glass tube that is in close contact with the lead wire integrated with the electrode, the linear expansion coefficient (linear expansion coefficient) of the glass tube must be reduced. First, the lead-in wire needs to be made of a metal having a small coefficient of linear expansion. In addition, when sputtering occurs in the discharge tube, a deterioration phenomenon of the light emission luminance of the discharge tube occurs due to a deterioration phenomenon of the metal constituting the electrode assembly of the electrode and the lead wire or a blackening phenomenon of the glass tube. It is desirable to form the electrode assembly from a metal that is difficult to cause sputtering in the discharge tube. For this reason, in consideration of sputtering resistance, linear expansion coefficient, chemical stability, and manufacturing price, it is desirable to provide an electrode assembly made of, for example, tungsten (W) or molybdenum (Mo). However, it is extremely difficult to form an electrode assembly by welding an electrode made of tungsten (W) or molybdenum (Mo), which is a refractory metal, and a lead wire by welding at the bottom of the electrode. Therefore, for example, in Patent Document 1 below, a low melting point metal such as nickel (Ni) is sandwiched between an electrode formed together with a high melting point metal such as tungsten (W) or molybdenum (Mo) and a lead wire, An electrode assembly is disclosed that is welded to the bottom surface of the electrode.

  In this electrode assembly, the electrode formed in the cup shape can suppress the voltage drop at the electrode by generating a hollow effect, but it is easy to draw tungsten (W) and molybdenum (Mo) which are difficult to draw. There was a difficulty that could not be formed. For this reason, for example, in Patent Document 2 below, refractory metal such as nickel (Ni) or tungsten (W) or molybdenum (Mo) including an electron emitting member is used as a submicron-sized powder, and the powder It is mixed with a two-part binder resin having thermoplasticity that is dispersed and supported, heated and melt-kneaded, and the kneaded product is poured into a mold to form the electrode and lead wire base into an integral shape, and then the two-part binder resin is added. An electrode is disclosed in which a porous structure having a communication hole is formed by degreasing, and further, the electrode and the lead wire base are integrated by sintering. Patent Document 2 shows a lead wire made of nickel (Ni), which is a low melting point metal, as a lead wire tip portion welded to the lead wire base.

JP 2005-327559 A JP-A-2005-71972

  When the electrode of Patent Document 2 is formed, a powdery body containing nickel (Ni) or an electron-emitting member and mainly made of a refractory metal such as tungsten (W) or molybdenum (Mo) is used as a cup-shaped electrode portion. When the glass tube is sealed, the glass beads surround the periphery of the lead-in base and weld to the lead-in base when the glass tube is sealed, but the surface roughness of the lead-in base cannot be smoothed. Therefore, the introduction line base and the glass beads cannot be adhered with sufficient adhesive strength, and a communication hole is formed between the introduction line base and the glass beads. If a communication hole is formed between the introduction wire base and the glass bead, a closed space with good airtightness cannot be formed in the glass tube, and the discharge gas filled in the glass tube is discharged through the communication hole. Or the atmosphere outside the discharge tube flows into the closed space of the discharge tube through the communication hole.

  Therefore, the present invention can suppress the outflow of the discharge gas in the discharge tube and the inflow of the atmosphere outside the discharge tube, and the lead wire composed of the electrode made of a metal sintered body containing a refractory metal and the refractory metal. It is an object of the present invention to provide an electrode assembly that can be welded with high mechanical strength and a method for producing the same. In addition, the present invention is resistant to thermal shock and can suppress the deterioration of light emission luminance due to the deterioration of the electrode of the electrode assembly or the blackening phenomenon of the bulb (12), and also suppresses the life reduction due to the discharge of the discharge gas or the inflow of outside air. An object of the present invention is to provide a discharge tube that can be used.

  An electrode assembly (4) according to the present invention comprises a first substrate made of a first metal having a low melting point, and a plurality of hard particles made of a second metal having a high melting point that is in close contact with the first substrate. The lead wire made of a third metal having a high melting point and having an end portion (2a) forming an end face (2b) to be joined to the electrode (1) composed of a sintered metal body including (2) and a fillet portion that annularly joins the outer peripheral portion (2c) of the end portion (2a) and the electrode (1) around the end surface (2b) of the end portion (2a) of the lead-in wire (2) ( And 3). The first metal in the electrode (1) is in close contact with the hard particles and has a lower hardness than the second metal, and the fillet (3) is made of a fourth metal having a melting point lower than that of the second metal. And a hard particle that is diffused from the first substrate and retained within at least a portion of the second substrate. The electrode (1) contains high melting point hard particles, and the first metal in the electrode (1) is in close contact with the hard particles, so that the spatter resistance of the electrode (2) is improved and the electrode assembly (4 ) Operating life can be extended. In addition, the electrode (1) can be formed in a desired shape with the first metal having a low melting point. Further, the end surface (2b) of the end portion (2a) of the lead-in wire (2) is joined to the electrode (1), and the joint portion between the electrode (1) and the lead-in wire (2) is formed by the fillet portion (3). Expand and increase the adhesion area between the electrode (1) and the lead-in wire (2) to improve the adhesion, so that the electrode (1) and the lead-in wire (2) can be welded with high mechanical strength . Since the fillet portion (3) holds the hard particles in at least a part of the second base material having a melting point lower than that of the second metal of the hard particles, the electrode (1) and the fillet portion (3) It is possible to obtain an electrode assembly (4) in which the thermal shock or vibration shock at the interface is alleviated and the electrode (1) and the lead-in wire (2) are welded with high mechanical strength. Furthermore, since the lead-in wire (2) is made of a high melting point metal and has a smooth surface, the glass tube (valve) is sealed by welding glass beads around the base of the lead-in wire (2). In addition, the base of the lead-in wire (2) and the glass beads are in close contact with each other with sufficient adhesive strength. For this reason, the communication hole formed between the base portion of the lead-in wire (2) and the glass beads can be suppressed, and the outflow of discharge gas and the inflow of outside air can be suppressed.

  The electrode assembly (4) according to the present invention is produced by mixing a powdery first metal having a low melting point and hard particles made of a second metal having a melting point higher than that of the first metal. And forming a metal sintered body electrode (1) having a large number of hard particles in close contact with the first substrate made of the first metal by sintering the powder mixture into a cup shape. And welding one end (2a) of the lead wire (2) made of the high melting point third metal to the electrode (1) at a temperature equal to or higher than the melting point of the first metal. A fillet portion (3) made of a second base material made of a fourth metal having a lower melting point than the second metal is formed around the joint between the electrode (1) and the lead-in wire (2) by a welding process. And a step of diffusing hard particles contained in the electrode (1) into the second substrate. In this production method, when the glass beads are welded around the base of the lead-in wire (2) to seal the glass tube (bulb), the base of the lead-in wire (2) made of a high melting point metal having a smooth surface And glass beads can be brought into close contact with each other with sufficient adhesive strength, so that a communication hole formed between the base of the lead-in wire (2) and the glass beads can be suppressed, and discharge of discharge gas and inflow of outside air can be suppressed. . And an electrode (1) obtained by mixing hard particles made of a second metal having a high melting point and a powdery first metal having a lower melting point than the hard particles made of the second metal, and sintering them in a cup shape; When welding the hard particles made of two metals and the lead wire (2) made of the same or different high melting point metal, the melting point of the first metal at the joint between the electrode (1) and the lead wire (2) When heating is performed by applying the thermal energy at the above temperature, the first metal of the electrode (1) to which the thermal energy is applied melts, and hard particles made of the second metal of the electrode (1) cannot be supported. . As a result, the hard particles made of the second metal of the electrode (1) diffuse into the base material of the fillet part (3) made of a metal having a relatively low melting point, so that the electrode (1) and the fillet part (3 The electrode assembly (4) with high reliability can be obtained by relieving the thermal shock or vibration shock at the interface with the above. Further, a fillet portion (3) is formed around the joint portion between the electrode (1) and the lead-in wire (2), and the fillet portion (3) is joined to the electrode (1) and the lead-in wire (2). The electrode (1) and the lead-in wire (2) can be welded with a high mechanical strength in order to increase the bonding area by expanding the.

  A discharge tube (11) using an electrode assembly (4) according to the present invention has an electrode (1) of an electrode assembly (4) disposed in a closed space (13) of a bulb (12) and an electrode (1 ) Embedded portion (2d) of lead wire (2) joined to each end (12a) of valve (12), and lead-out portion (2e) adjacent to embedded portion (2d) is connected to valve ( The electrode assembly (4) is fixed to each end portion of the valve (12) forming the closed space (13) by being led out to the outside of 12). Deterioration of electrode (1) of electrode assembly (4) or blackening of valve (12) because electrode assembly (4) containing hard particles made of a high melting point second metal with high spatter resistance is used. It is possible to obtain a discharge tube (11) that can suppress a decrease in light emission luminance due to the phenomenon. Further, when the embedded portion (2d) of the introduction line (2) is fused to each end (12a) of the valve (12), each of the embedded portion (2d) of the introduction line (2) and each of the valves (12) Since the end (12a) can be adhered with sufficient adhesive strength, a communication hole is generated between the embedded portion (2d) of the lead-in wire (2) and each end (12a) of the valve (12). By suppressing the outflow of discharge gas and the inflow of outside air, it is possible to suppress a decrease in the life of the discharge tube (11). Further, the fillet portion (3) of the electrode assembly (4) is formed of hard particles made of the second metal of the electrode (1) in a base material made of a metal having a lower melting point than the hard particles made of the second metal. Therefore, the thermal shock or vibration shock at the interface between the electrode (1) and the fillet portion (3) is relieved. Thereby, it is possible to obtain the discharge tube (11) that is resistant to thermal shock and vibration shock due to heat generation of the electrode assembly (4) during lighting.

  According to the present invention, when sealing the glass tube (bulb) by welding the glass beads around the base of the introduction line, without generating a communication hole between the base of the introduction line and the glass beads, The glass beads can be fixed and adhered to the base of the lead-in wire with sufficient adhesive strength, and discharge of discharge gas from the inside of the glass tube and inflow of air from the outside of the glass tube can be prevented. Further, the fillet portion formed around the joint between the electrode and the lead-in line can increase the adhesion area between the electrode and the lead-in line, and the electrode and the lead-in line can be welded with high mechanical strength. Furthermore, the hard particles made of the second metal of the electrode diffuse into the fillet part and homogenize it, so that the thermal and vibration shocks at the interface between the electrode and fillet part are alleviated and the service life is extended. In addition, a highly reliable electrode assembly can be obtained.

  Embodiments of an electrode assembly and its manufacturing method according to the present invention will be described below with reference to FIGS. An embodiment of a discharge tube using the electrode assembly according to the present invention will be described with reference to FIG.

As shown in FIG. 2, the electrode assembly (4) of the present embodiment includes a cup-shaped electrode (1) made of a sintered metal body and having a U-shaped cross section, and a bottom portion of the electrode (1) ( 1a) the lead wire (2) where the end face (2b) of one end (2a) is joined, and the electrode (1) provided around the joint of the electrode (1) and lead wire (2) And a fillet portion (3) that annularly joins the outer peripheral portion (2c) of the end portion (2a) of the lead-in wire (2). As shown in FIG. 5, the cup-shaped electrode (1) has a high melting point (melting point: about 3400 ° C.) dispersed in the base material (matrix) of the sintered metal body and a linear expansion coefficient of 2.6 × 10. Tungsten particles (W) as hard particles composed of a relatively small second metal at ^-6 / ° C and tungsten particles (W) as a support material (binder) for tungsten particles (W) ) And nickel (Ni) as a first metal having a lower melting point and a larger linear expansion coefficient. Incidentally, the linear expansion coefficient of nickel (Ni) is 6.6 × 10 ⁻⁶ / ° C., and the melting point is 1450 ° C. The lead-in wire (2) is made of the same component as the tungsten particles (W) in the electrode (1), that is, tungsten (W) having a high melting point as the third metal. The purity of tungsten (W) in the lead-in wire (2) is 99% by weight or more.

  In the electrode assembly (4) of the present embodiment, the fillet portion (3) formed when welding the electrode (1) and the lead-in wire (2) includes the electrode (1) and the lead-in wire (2). The cross section of the fillet portion (3) is from the other end side of the lead-in wire (2) to one end portion (joint side with the electrode (1)). It is formed in a tapered shape that expands in diameter. Nickel (Ni) as the fourth metal contained in the base material of the fillet portion (3) is nickel (Ni) and tungsten particles (W) dispersed in the base material of the sintered metal body, lead wire ( Any of the tungsten (W) constituting 2) is excellent in wettability, affinity or mutual diffusion. Further, the fillet portion (3) increases the bonding area between the electrode (1) and the lead-in wire (2), so that the electrode (1) and the lead-in wire (2) can be welded with high mechanical strength. it can. Further, in the base material of the fillet portion (3), tungsten particles (W) in the electrode (1), and further the same metal as nickel (Ni) are dispersed, so the electrode (1) and fillet portion ( An electrode assembly (4) resistant to thermal shock or vibration shock at the interface with 3) can be obtained. That is, an electrode assembly (4) having a long service life and high reliability can be obtained. Furthermore, the high melting point tungsten particles (W) bonded by the low melting point nickel (Ni) contained in the electrode (1) impart high sputtering resistance to the electrode (1), and the nickel (Ni) is a tungsten particle. Since (W) is firmly and closely joined, an electrode (1) having a long service life and high reliability can be obtained. When obtaining the electrode assembly (4) of the present embodiment, as shown in FIG. 1, a low melting point metal (for example, as a bonding material (5) between the electrode (1) and the lead-in wire (2) is used. When welding is performed with nickel (Ni)), some of the nickel (Ni) and tungsten particles (W) in the electrode (1) diffuse into the base material containing the low melting point metal in the bonding material (5). The fillet portion (3) having the above-described metal structure is obtained.

  When the electrode assembly (4) shown in FIG. 2 is manufactured, first, submicron or micron-sized tungsten particles having a high melting point, a relatively small linear expansion coefficient, and an average particle size of about 0.2 to several μm. (W) and powdered nickel (Ni), which is a metal having a lower melting point and a larger linear expansion coefficient than tungsten (W), are kneaded into a plurality of binder resins, tungsten particles (W) and powdery The nickel (Ni) mixture is sufficiently dispersed in the binder resin. On the other hand, one or more cup-shaped cavities are formed in the molding die mounted on the resin molding part of the injection molding apparatus, and tungsten particles (W) measured by a heating cylinder and A kneaded product containing nickel (Ni) particles and blended and kneaded with the binder resin in the above-described step is filled in the cavity of the molding die. The kneaded material filled in the cavity of the molding die is cooled and solidified to form a cup-shaped electrode molded body (green body). Thereafter, when the cup-shaped electrode molded body is taken out from the molding die and at least one binder resin is degreased, the remaining binder resin, tungsten particles (W) and nickel (Ni) supported on the resin are retained. ) The molded body containing particles is formed in a porous structure in which one trace of the eluted binder resin is left as a fine communication hole as a whole. The porous molded body is larger than the final shape in anticipation of the amount of shrinkage generated in the sintering process.

  Next, the porous molded body is put into a pressure sintering furnace, and the binder resin remaining in the molded body is further degreased. When the binder resin remaining in the molded body is further degreased, the temperature in the pressure sintering furnace is the melting point of nickel (Ni) contained in the molded body: 1455 ° C. or more and tungsten particles contained in the molded body (W ) At a recrystallization temperature of 1150 to 1350 ° C. (for example, 1300 ° C.) or higher and a melting point of tungsten particles (W) contained in the compact is 3422 ° C. or less, for example, 1500 ° C. By dissolving and further growing tungsten particles (W) in a rod shape by recrystallization and sintering and bonding the tungsten particles (W) with nickel (Ni) while applying pressure, the cup shape shown in FIG. 1 is obtained. An electrode (1) is formed. In the present embodiment, the tungsten particles (W) are densely integrated at a temperature lower than the melting point to sinter the electrode, and thus the obtained electrode (1) is referred to as “sintered electrode”. In practice, it is preferable to sinter using a hip furnace capable of heating the compact in the sintering furnace under pressure. In the sintered electrode (1), as shown in FIG. 5, fine gaps between tungsten particles (W) are tightly closed by nickel (Ni). The action of nickel (Ni) in the sintered electrode (1) is to prevent slow leaks, as well as good wettability and diffusibility with other metals, nickel (Ni) compared to tungsten (W) alone Therefore, there is an advantage that welding with different metals becomes easy. When the sintering is completed, a cup-shaped sintered electrode (1) having a desired dimension (for example, an outer diameter of about 2 mm) is obtained. The ratio of nickel (Ni) contained in the sintered electrode (1) is 0.5 to 10.0% by weight, more preferably 0.5 to 5.0%, and the balance is tungsten (W). Is desirable.

  Next, as shown in FIG. 1, it is made of nickel (Ni) having a melting point lower than that of the tungsten particles (W) contained in the cup-shaped electrode (1), has an outer diameter of 1.7 mm and a thickness of 0. One end (2a) of the lead wire (2) having an outer diameter of 0.8 mm and a bottom portion (1a) of the electrode (1) formed by powder metallurgy and polishing tungsten (W) powder with a 0.05 mm bonding material (5) Place between. Thereafter, for example, as shown in FIG. 6, the glass beads (14) are inserted into the embedded portion (2d) of the lead-in wire (2), and the welding power source (2e) is connected to the outlet portion (2e) adjacent to the embedded portion (2d). 21) Connect the fixed electrode (22) connected to the cathode, and insert the movable electrode (23) connected to the anode of the welding power source (21) into the cylindrical part (1b) of the electrode (1). The tip (23a) of the movable electrode (23) is brought into contact with the bottom (1a) of the cup inner wall of the electrode (1) while pressing the movable electrode (23) toward the lead-in line (2), and the electrode (1) Resistance welding is performed by flowing a welding current of 1200 amperes or more through the bottom (1a), joining material (5) and lead-in wire (2) for a period of 4 milliseconds, to the bottom (1a) of the cup-shaped electrode (1). Secure the lead-in wire (2). Alternatively, as shown in FIG. 7, 1 kilowatt laser beam (33) output from the condenser lens (32) of the high-power laser device (31) is converted into the bottom (1a) of the inner wall of the cup of the electrode (1). For 34 milliseconds, and 0.7 seconds later, 1 kilowatt laser beam (33) is further irradiated to the bottom (1a) of the inner wall of the cup of the electrode (1) for 34 milliseconds, and laser welding is performed. The lead-in wire (2) is fixed to the bottom (1a) of the cup-shaped electrode (1). Various conditions such as the welding current or laser light output are appropriately determined depending on the thickness of the bottom (1a) of the electrode (1) and the state of the metal. Further, the welding temperature of the joint surface with the lead-in wire (2) at the bottom (1a) of the electrode (1) is equal to or higher than the melting point of nickel (Ni) constituting the joint material (5) and is contained in the electrode (1). It is set to be equal to or higher than the melting temperature of (Ni) and lower than the melting point of tungsten (W) constituting the lead-in wire (2). Therefore, most of the tungsten particles (W) interposed between the electrode (1) and the lead-in wire (2) are not alloyed, but may be partially alloyed. In this way, when a large welding current is applied or a high-power laser beam or electron is irradiated to apply thermal energy only to the region including the junction between the electrode (1) and the lead-in wire (2), the heating is performed. In the region of the electrode (1), the low melting point nickel (Ni) sandwiched between the high melting point tungsten particles (W) dispersed in the base material of the sintered metal constituting the electrode (1) melts. . As a result, the bond between the tungsten particles (W) dispersed in the base material of the sintered metal becomes loose, and the molten nickel (Ni) does not function as a support material between the tungsten particles (W).

  At this time, the pressing force is applied to the electrode (1) and the lead-in wire (2) to crush the bonding material (5), so that the nickel (Ni) in the molten bonding material (5) becomes the electrode (1 ), And on the contrary, the unsupported tungsten particles (W) contained in the electrode (1) are melted in the nickel (Ni) in the molten bonding material (5) or the molten nickel (Ni in the electrode (1)). ) Is diffused to one or both of the inside, and a part of the diffusion overflows outside the electrode (1). Part of the tungsten particles (W) dispersed in nickel (Ni) overflowing outside the electrode (1) scoops up the lead wire (2) or leads from the bottom (1a) of the electrode (1). The electrode (1) and the lead-in wire (2) are joined so as to fill the region surrounding the outer surface of (2). As a result, as shown in FIG. 2, it has a metal structure in which a part of tungsten particles (W) of the electrode (1) is dispersed in a base material made of nickel (Ni) which is a relatively low melting point metal. A tapered fillet portion (3) is formed around one end (2a) of the lead-in wire (2). That is, the fillet (3) has a metal structure in which tungsten particles (W) in the electrode (1) are dispersed in a base material made of the same metal as nickel (Ni) contained in the electrode (1). The electrode (1) and the introduction line (2) are formed around the joint of the electrode (1) and the introduction line (2) while increasing the adhesion area between the electrode (1) and the introduction line (2). Join one end (2a) of the line (2). In this way, the electrode (1) made of a sintered body of tungsten particles (W) containing nickel (Ni) and the lead-in wire (2) made of tungsten, which is a high melting point hard metal, were firmly and closely joined. An electrode assembly (4) is obtained.

  When producing the electrode assembly (4) of the present embodiment, the fluidity of the fluid produced by blending the binder resin constituting the resin adhesive into the tungsten particles (W) and powdered nickel (Ni). The mixture may be filled into a cavity of a molding die, and a cup-shaped molded body may be easily molded by injection molding. Further, when welding the electrode (1) and the lead-in wire (2), if the electrode (1) is heated by applying heat energy to the contact portion between the bonding material (5) and the lead-in wire (2), the electrode Nickel (Ni) in the bonding material (5) melts and mixes with the nickel (Ni) in (1), and a part of the mixture flows out of the electrode (1), leading to the lead-in wire (2 The fillet portion (3) that rises from the fillet portion (3) is formed, and the electrode (1) and the lead-in wire (2) can be easily and firmly joined to each other by the nickel (Ni) of the fillet portion (3). At this time, among the tungsten particles (W) in the electrode (1), the tungsten particles (W) loosened by melting of nickel (Ni) between the particles, together with the above mixture, in the fillet portion (3) When the low melting point metal is sandwiched between the electrode made of the high melting point metal shown in Patent Document 1 and the lead wire, the difference in the linear expansion coefficient from the electrode (1) of the tungsten particles (W) to the weld is diffused. The electrode assembly (4) with high reliability can be obtained by relaxing in comparison.

  When manufacturing the electrode assembly (4), the bonding material (5) of FIG. 1 is not disposed between the bottom (1a) of the electrode (1) and one end (2a) of the lead-in wire (2). 3, the bottom (1a) of the cup-shaped electrode (1) composed of a sintered body containing tungsten particles (W) and nickel (Ni) and one end (2a of the tungsten lead wire (2)) May be directly butted to weld the electrode (1) and the lead-in wire (2) to form the electrode assembly (4) shown in FIG. In this case, since the bonding material (5) is not provided, the volume of the fillet portion (3) is reduced as shown in FIG. 4, so that the bonding area is reduced as compared with the case shown in FIG.

  Alternatively, when manufacturing the electrode assembly (4), without using a binder resin, the tungsten particles (W) and powdered nickel (Ni) are mixed to form a powder mixture, While a powder mixture of tungsten particles (W) and nickel (Ni) powder is charged into a pressure sintering furnace and pressed and consolidated, it is heated to a temperature of 600 ° C. or higher, for example, about 700 ° C. to form a cup shape. The electrode (1) may be formed by sintering. In this case, the step of kneading the tungsten particles (W) and nickel (Ni) particles and the binder resin and the step of removing the binder resin from the molded body can be omitted, and the sintered electrode (1) can be formed in a short time. Can be formed.

In the above embodiment, when welding the electrode (1) and the lead-in wire (2), nickel (Ni) in the vicinity of the region in contact with the lead-in wire (2) at the bottom (1a) of the electrode (1) As a result, the bonds between tungsten particles (W) in the same region become loose. As a result, the tungsten particles (W) in which the bonding between the particles is loose, together with one or both of nickel (Ni) in the bonding material (5) and molten nickel (Ni) in the electrode (1), Since it flows out of the electrode (1), the density of tungsten particles (W) in the vicinity of the area in contact with the lead-in line (2) at the bottom (1a) of the electrode (1) is compared with other areas of the electrode (1). Therefore, the thickness of the portion joined to the lead-in line (2) and fillet part (3) of the bottom part (1a) of the electrode (1) is slightly reduced or the tungsten particles (W) are slightly reduced. 1a) Slightly thinner than other parts. Therefore, the thickness of the portion joined to the lead wire (2) and fillet portion (3) of the bottom (1a) of the electrode (1) before welding is made thicker than the thickness of the other portion of the bottom (1a). Also good. Also, a low melting point metal containing metal particles having a large linear expansion coefficient such as a nickel (Ni) bonding material (5) containing tungsten particles (W) is interposed between the electrode (1) and the lead-in wire (2). You may let them. Further, the low melting point metals contained in the electrode (1) and the bonding material (5) may use different metal materials. Further, the refractory metal particles (hard particles made of the second metal) of the electrode (1) and the refractory metal constituting the lead-in wire (2) may use different metal materials. Further, the high melting point hard metal particles contained in the electrode (1) and the high melting point metal constituting the lead-in wire (2) are metals having a melting point of 2000 ° C. or higher, more preferably a melting point of 2000 ° C. or higher and a linear expansion coefficient. For example, tungsten (W) or molybdenum (Mo) can be used as a small metal. Further, as the low melting point metal constituting the interparticle metal and the bonding material (5) contained in the electrode (1), a metal having a melting point of 2000 ° C. or less, such as iron (Fe), platinum (Pt), cobalt (Co) Nickel (Ni), chromium (Cr), or an alloy containing at least one of these metals may be selected. Incidentally, the melting point of molybdenum (Mo) is 2620 ° C., and the linear expansion coefficient is 3.7 × 10 ⁻⁶ / ° C. Iron (Fe) has a melting point of 1540 ° C. and a linear expansion coefficient of 5.6 × 10 ⁻⁶ / ° C., and platinum (Pt) has a melting point of 1770 ° C. and a linear expansion coefficient of 6.6 × 10 ⁻⁶ / ° C. The melting point of cobalt (Co) is 1490 ° C. and the linear expansion coefficient is 6.8 × 10 ⁻⁶ / ° C. In addition, the electrode (1) has an electron emission property composed of a compound such as scandium (Sc), yttrium (Y), niobium (Nb), lanthanum (La), cerium (Ce), gadolinium (Gd), or thorium (Th). Materials may be included. The electrode (1) may have a complicated shape, but a cup shape that can reduce a voltage drop at the electrode (1) by the hollow effect is preferable.

  The electrode assembly (4) shown in FIGS. 1 to 5 can be applied to a discharge tube (11) such as a cold cathode fluorescent discharge tube (CCFL) shown in FIG. As shown in FIG. 8, the discharge tube (11) of the present embodiment includes a glass bulb (12) that forms a closed space (13) that accommodates a discharge gas, and an inner wall surface of the bulb (12). The electrode (1) of the electrode assembly (4) shown in FIGS. 1 to 5 is disposed in the closed space (13) of the bulb (12) and is made of glass beads (14). ) And the lead-out portion (2d) of the lead-in wire (2) joined to the electrode (1) via the lead (2) is fused to each end portion (12a) of the valve (12) and adjacent to the buried portion (2d). (2e) is led out of the valve (12), the electrode assembly (4) is fixed to each end (12a) of the valve (12), and a voltage is applied between the pair of electrode assemblies (4). Is applied to cause discharge between the electrodes (1) to emit light through the discharge gas filled in the closed space (13).

  In the discharge tube (11) of the present embodiment, since the electrode assembly (4) containing tungsten particles (W) having a small linear expansion coefficient is used, the deterioration of the electrode (1) of the electrode assembly (4) or the bulb The decrease in emission luminance due to the blackening phenomenon of (12) can be suppressed. Further, when the embedded portion (2d) of the introduction line (2) is fused to each end (12a) of the valve (12), each of the embedded portion (2d) of the introduction line (2) and each of the valves (12) Since the end (12a) can be adhered with sufficient adhesive strength, a communication hole is generated between the embedded portion (2d) of the lead-in wire (2) and each end (12a) of the valve (12). The discharge of the discharge gas in the bulb (12) and the inflow of the atmosphere outside the bulb (12) can be suppressed, and the life reduction of the discharge tube (11) can be suppressed. Further, the fillet portion (3) of the electrode assembly (4) is made of tungsten particles (W) of the electrode (1) in a base material made of nickel (Ni) which is a metal having a lower melting point than the tungsten particles (W). Therefore, the thermal shock at the interface between the electrode (1) and the fillet portion (3) is alleviated and welding is performed with high mechanical strength. This makes it possible to obtain a discharge tube (11) that is resistant to thermal shock and vibration shock due to heat generation of the electrode assembly (4) during lighting.

  INDUSTRIAL APPLICABILITY The present invention can be suitably applied to the production of an electrode constituted by a sintered body containing hard particles and intergranular metal and a discharge tube using the electrode.

Sectional drawing which shows one Embodiment of a structure of the electrode assembly by this invention Sectional drawing which shows the electrode assembly after welding with the structure of FIG. Sectional drawing which shows other embodiment of the structure of the electrode assembly by this invention Sectional drawing which shows the electrode assembly after welding with the structure of FIG. Sectional view showing the microstructure of the sintered electrode Configuration diagram when resistance welding the electrode assembly shown in FIG. Configuration diagram when laser welding the electrode assembly shown in FIG. Sectional view of a discharge tube using an electrode assembly according to the invention

Explanation of symbols

  (1) ・ ・ Electrode, (1a) ・ ・ Bottom, (1b) ・ ・ Cylinder, (2) ・ ・ Introduction wire, (2a) ・ ・ End, (2b) ・ ・ End face, (2c) ・ ・Peripheral part, (2d) ... Embedded part, (2e) ... Lead-out part, (3) ... Fillet part, (4) ... Electrode assembly, (5) ... Joining material, (11) ... Discharge tube, (12) ・ ・ Valve, (13) ・ ・ Enclosed space, (14) ・ ・ Glass beads, (21) ・ ・ Power supply for welding, (22) ・ ・ Fixed electrode, (23) ・ ・ Movable electrode , (23a)-tip, (31)-high power laser device, (32)-condensing lens, (33)-laser light, (W)-tungsten particles (consisting of a second metal) Hard particles), (Ni) ・ ・ Nickel (first metal),

Claims (8)

An electrode composed of a sintered metal body including a first base material made of a first metal having a low melting point and a plurality of hard particles made of a second metal having a high melting point that is in close contact with the first base material. When,
An introduction line made of a third metal having a high melting point and an end part forming an end face joined to the electrode;
A fillet portion that annularly joins the outer peripheral portion of the end portion and the electrode around the end face of the end portion of the introduction line,
The first metal in the electrode is in close contact with the hard particles and has a lower hardness than the second metal;
The fillet portion is diffused from the first base material and held in at least a part of the second base material made of a fourth metal having a melting point lower than that of the second metal. An electrode assembly comprising the hard particles. An electrode composed of a sintered metal body, and an introduction line joined to the bottom of the electrode,
The fillet portion provided around the lead-in line joined to the electrode extends the joint part between the bottom part of the electrode and the lead-in line in an annular shape,
The electrode includes a first metal constituting a first base of the sintered metal body, and hard particles composed of a second metal that is in close contact with the first metal,
The first metal has a low melting point and a large coefficient of linear expansion, and the second metal has a high melting point and a small coefficient of linear expansion,
The lead wire is made of a high melting point third metal,
The fillet part is diffused from the first base material and dispersed in at least a part of the second base material made of a fourth metal having a melting point lower than that of the second metal. An electrode assembly having a metallographic structure including the hard particles. The second metal and the third metal are selected from the group consisting of tungsten and molybdenum;
The electrode assembly according to claim 1, wherein the first metal and the fourth metal are nickel. Mixing a powdery first metal having a low melting point and hard particles composed of a second metal having a higher melting point than the first metal to form a powder mixture;
Sintering the powder mixture in a cup shape to form a metal sintered body electrode having a number of hard particles in close contact with the first substrate comprising the first metal;
Welding one end of a lead wire made of a high melting point third metal to the electrode at a temperature equal to or higher than the melting point of the first metal,
By the welding step, a fillet portion made of a second base material made of a fourth metal having a melting point lower than that of the second metal is formed around the joint portion between the electrode and the lead-in wire, and the electrode And a step of diffusing the hard particles contained in the second base material into the second base material. Mixing a powdery first metal having a low melting point and hard particles composed of a second metal having a higher melting point than the first metal to form a powder mixture;
Sintering the powder mixture in a cup shape to form an electrode composed of a metal sintered body having a large number of the hard particles in close contact with the first substrate made of the first metal;
Welding one end of a lead wire made of a high melting point third metal to the electrode at a temperature equal to or higher than the melting point of the first metal,
A fillet portion in which a part of the hard particles contained in the electrode is diffused from the electrode into the second base material by the welding process is provided around the joint portion of the electrode and the lead-in wire. A method of manufacturing an electrode assembly, comprising: forming an electrode assembly. Disposing a bonding material made of the first metal between the electrode and the lead-in wire;
The manufacturing method of the electrode assembly of Claim 4 or 5 including the process of welding the said electrode and the said introductory wire through the said joining material. The second metal and the third metal are selected from the group consisting of tungsten and molybdenum;
The method for producing an electrode assembly according to any one of claims 4 to 6, wherein the metal constituting the first metal and the fillet portion is nickel.   An electrode assembly according to any one of claims 1 to 3 or an electrode assembly manufactured according to any one of claims 4 to 7 is arranged in a closed space of a valve and joined to the electrode. A wire embedded portion is fused to each end portion of the bulb, and a lead-out portion adjacent to the buried portion is led out to the outside of the valve so that the electrode is formed at each end portion of the valve forming the closed space. A discharge tube having a fixed assembly.

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