WO2020171065A1 - Composant de cathode pour lampes à décharge, lampe à décharge et procédé de production d'un composant de cathode pour lampes à décharge - Google Patents

Composant de cathode pour lampes à décharge, lampe à décharge et procédé de production d'un composant de cathode pour lampes à décharge Download PDF

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Publication number
WO2020171065A1
WO2020171065A1 PCT/JP2020/006284 JP2020006284W WO2020171065A1 WO 2020171065 A1 WO2020171065 A1 WO 2020171065A1 JP 2020006284 W JP2020006284 W JP 2020006284W WO 2020171065 A1 WO2020171065 A1 WO 2020171065A1
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Prior art keywords
thorium
discharge lamp
tungsten
crystal
less
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PCT/JP2020/006284
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English (en)
Japanese (ja)
Inventor
斉 青山
雅恭 溝部
憲治 友清
康彦 中野
Original Assignee
株式会社 東芝
東芝マテリアル株式会社
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Application filed by 株式会社 東芝, 東芝マテリアル株式会社 filed Critical 株式会社 東芝
Priority to CN202080003268.4A priority Critical patent/CN112262454B/zh
Priority to JP2021502027A priority patent/JP7098812B2/ja
Publication of WO2020171065A1 publication Critical patent/WO2020171065A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/067—Main electrodes for low-pressure discharge lamps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/073—Main electrodes for high-pressure discharge lamps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems

Definitions

  • the embodiment relates to a discharge lamp cathode component and a discharge lamp.
  • the -Discharge lamps can be broadly divided into two types: low-pressure discharge lamps and high-pressure discharge lamps.
  • the low-pressure discharge lamp includes various arc discharge type discharge lamps such as general lighting, special lighting used for roads and tunnels, paint curing device, ultraviolet (UV) curing device, sterilizing device, light cleaning device for semiconductors, etc. ..
  • High-pressure discharge lamps include water and sewage treatment equipment, general lighting, outdoor lighting such as stadiums, UV curing equipment, exposure equipment such as semiconductors and printed circuit boards, wafer inspection equipment, high-pressure mercury lamps such as projectors, metal halide lamps, and ultra-high pressure. Examples thereof include a mercury lamp, a xenon lamp, and a sodium lamp.
  • the discharge lamp is used in various devices such as a lighting device, a video projection device, and a manufacturing device.
  • a projection type display device using a discharge lamp is known.
  • home theaters and digital cinemas have become popular.
  • These use a projection type display device called a projector.
  • the consumption of the electrodes of the discharge lamp affects the life of the lamp and the flicker of the emitted light.
  • PWM pulse width modulation
  • the consumption of electrodes of the discharge lamp can be managed by the control circuit.
  • the cathode part manufactured by using the above technique was applied with a voltage while the cathode part was energized and heated, and after 10 hours, the emission current density (mA/mm 2 ) and after 100 hours were applied. It is known to have excellent characteristics by measuring the emission current density (mA/mm 2 ) of.
  • a conventional cathode part for a discharge lamp exhibits excellent durability for about 100 hours, but the durability deteriorates for a longer time than that.
  • the discharge lamp cathode component of the embodiment includes a body portion having a wire diameter of 2 mm or more and 35 mm or less, and a tip portion tapered from the body portion.
  • the cathode component contains a tungsten alloy containing 0.5 mass% or more and 3 mass% or less of thorium in terms of ThO 2 .
  • the electron backscattering diffraction analysis of the region including the center and having a unit area of 90 ⁇ m ⁇ 90 ⁇ m in the cross section passing through the center of the body part and along the length direction of the body part is obtained by electron backscattering diffraction analysis.
  • the obtained crystal grain map has a tungsten crystal grain containing tungsten and a thorium crystal grain containing thorium.
  • a thorium crystal grain is defined by a thorium crystal region that includes thorium and has a crystal orientation angle difference of ⁇ 5 degrees or more and +5 degrees or less at two or more consecutive measurement points in the crystal grain map.
  • the grain size of the thorium crystal grain is defined by the equivalent circle diameter of the thorium crystal region in the crystal grain map.
  • the grain size with a cumulative frequency of 90% is 3.0 ⁇ m or more.
  • FIG. 3 is a diagram showing a cumulative distribution graph of thorium crystal grains of Example 1 and Comparative Example 1. It is a figure which shows the frequency distribution graph of the thorium crystal grain of Example 1 and Comparative Example 1. It is a figure which shows the constructional example of a discharge lamp.
  • FIG. 1 is a side view showing an example of a cathode part for a discharge lamp.
  • the discharge lamp cathode component 1 includes a body portion 2 having a wire diameter of 2 mm or more and 35 mm or less, and a tip portion 3 extending from the body portion 2 so as to taper.
  • FIG. 1 shows a cathode part 1 for a discharge lamp, a body part 2, a tip part 3, a center 4, a line W of the body part 2 and a length T of the body part 2.
  • FIG. 2 is a diagram showing an example of a cross section in the length direction of the center 4 of the body portion 2.
  • the discharge lamp cathode part may be simply referred to as “cathode part”.
  • the body 2 has a columnar shape.
  • the wire diameter W is the diameter of the circumferential cross section. When the circumference is an ellipse, the wire diameter W has the largest diameter. If the wire diameter W of the body 2 is less than 2 mm, the discharge lamp may be insufficient in light emission. When the wire diameter W exceeds 35 mm, the discharge lamp becomes large. Therefore, the wire diameter W is preferably 2 mm or more and 35 mm or less, and more preferably 5 mm or more and 20 mm or less.
  • the length T of the body portion 2 is preferably 10 mm or more and 600 mm or less.
  • the tip 3 has a shape that tapers from the body 2. Therefore, the region from the point where the taper starts to the end is the tip 3.
  • the tip 3 has an acute-angled shape in a cross section in the direction a of the cathode component 1.
  • the cathode component 1 is not limited to such a shape, and in the cross section of the cathode component 1 in the direction a, the tip portion 3 may have another shape such as an R shape or a planar shape.
  • the cathode part is made of a tungsten alloy containing 0.5 mass% or more and 3 mass% or less of thorium (also referred to as a thorium component) in terms of oxide (ThO 2 ). If the content is less than 0.5% by mass, the effect of addition is small, and if it exceeds 3% by mass, the sinterability and workability are deteriorated. Therefore, the content of thorium is preferably 0.5% by mass or more and 3% by mass or less, further preferably 0.8% by mass or more and 2.5% by mass or less in terms of oxide (ThO 2 ).
  • the crystal grain map obtained by the EBSD analysis is a crystal grain containing tungsten (tungsten). Crystal grains) and crystal grains containing thorium (thorium crystal grains).
  • EBSD irradiates a crystal sample with an electron beam.
  • the electrons are diffracted and emitted from the sample as reflected electrons.
  • XRD X-ray diffraction
  • EBSD can measure the crystal orientation of individual crystals.
  • An analytical method similar to EBSD is sometimes called electron backscattering pattern (EBSP) analysis.
  • EBSD analysis was performed by JEOL Co., Ltd. thermal field emission scanning electron microscope (TFE-SEM) JSM-6500F and TSL Solution Co., Ltd. DigiView IV slow scan CCD camera, OIM Data Collection ver. 7.3x, OIM Analysis server. Performed using 8.0.
  • TFE-SEM thermal field emission scanning electron microscope
  • DigiView IV slow scan CCD camera OIM Data Collection ver. 7.3x
  • OIM Analysis server Performed using 8.0.
  • the measurement conditions of the EBSD analysis include an electron beam acceleration voltage of 20 kV, an irradiation current of 12 nA, a sample inclination angle of 70 degrees, a measurement area unit area of 90 ⁇ m ⁇ 90 ⁇ m, and a measurement interval of 0.3 ⁇ m/step.
  • the cross section 5 is a measurement surface, and the cross section 5 is irradiated with an electron beam to obtain a diffraction pattern.
  • the measurement surface of the measurement sample is polished until the surface roughness Ra becomes 0.8 ⁇ m or less.
  • the cross section 5 passes through the center of the tip portion 3 and the center 4 of the thickness T of the body portion 2.
  • the measurement area includes the center 4.
  • a tungsten crystal grain is defined by a tungsten crystal region that contains tungsten and has a crystal orientation angle difference between two or more consecutive measurement points of -5 degrees or more and +5 degrees or less in the crystal grain map.
  • a tungsten crystal region in which two or more measurement points where the crystal orientation difference is within 5 degrees is continuously present is identified as a tungsten crystal grain.
  • the tungsten crystal region can be identified by using the EBSD analysis device.
  • the grain size of the tungsten crystal grain is defined by the circle equivalent diameter of the tungsten crystal region in the crystal grain map.
  • the average grain size of the plurality of tungsten crystal grains is, for example, 20 ⁇ m or less, preferably 15 ⁇ m or less.
  • the average grain size is calculated from the identified crystal grains in the area of 90 ⁇ m ⁇ 90 ⁇ m unit area.
  • the particle diameter is equivalent to a circle.
  • the boundary of the region is calculated as the end of the crystal grain.
  • the average particle diameter is the median diameter. That is, it is the cumulative particle size.
  • a thorium crystal grain is defined by a thorium crystal region that includes thorium and has a crystal orientation angle difference between two or more consecutive measurement points of ⁇ 5 degrees or more and +5 degrees or less in the crystal grain map.
  • a thorium crystal region in which two or more measurement points where the crystal orientation difference is within 5 degrees is continuously present is identified as a thorium crystal grain.
  • the thorium crystal region can be identified by using the EBSD analysis device.
  • the grain size of the thorium crystal grain is defined by the circle equivalent diameter of the thorium crystal region in the crystal grain map.
  • the particle size distribution of a plurality of thorium crystal grains is represented by a cumulative distribution graph and a frequency distribution graph.
  • the cumulative distribution graph shows the relationship between the particle size ( ⁇ m) on the horizontal axis and the cumulative frequency (%) on the vertical axis.
  • the horizontal axis is divided into a plurality of particle size ranges at intervals of, for example, 0.125 ⁇ m to 0.25 ⁇ m.
  • the cumulative distribution graph of thorium crystal grains shows the relationship between the grain size of thorium crystal grains existing in a region having a unit area of 90 ⁇ m ⁇ 90 ⁇ m and the cumulative frequency.
  • the upper limit of the cumulative frequency is 100%.
  • the frequency distribution graph shows the relationship between the particle size ( ⁇ m) on the horizontal axis and the frequency (%) on the vertical axis.
  • the horizontal axis is divided into a plurality of particle size ranges at intervals of, for example, 0.125 ⁇ m to 0.25 ⁇ m.
  • the frequency distribution graph relatively indicates, for example, of which grain size the grain size is large among grain sizes of the grain grains existing in the grain grain map.
  • the grain size D 90 having a cumulative frequency of 90% is preferably 3.0 ⁇ m or more.
  • the upper limit of the particle size D 90 is not particularly limited, but is 4.5 ⁇ m or less, for example.
  • the grain size of the thorium crystal grain is defined by the circle equivalent diameter of the thorium crystal region in the crystal grain map.
  • the particle size D 90 of 3.0 ⁇ m or more indicates that the particle size of the thorium crystal grains is relatively large.
  • Conventional cathode components have a particle size D 90 of less than 3.0 ⁇ m.
  • Thorium crystal grains exist at grain boundaries between tungsten crystal grains. By enlarging the thorium crystal grain, grain growth of the tungsten crystal grain can be suppressed.
  • the effect of suppressing the grain growth of the base material crystal grain by allowing the grain boundary crystal grain such as thorium crystal grain to exist in the grain boundary of the base material crystal grain such as tungsten crystal grain is also called a pinning effect. If the pinning effect is not uniform, it will cause the base material crystal grains to grow rapidly. The pinning effect can be made uniform by increasing the grain size of the thorium crystal grains. As a result, the tungsten crystal grains can be grown uniformly.
  • the grain size D 100 having a cumulative frequency of 100% is preferably 4.8 ⁇ m or less, and more preferably 4.5 ⁇ m or less.
  • Thorium crystal grains evaporate due to emission. Therefore, if there are coarse thorium crystal grains, the trace of evaporation of the thorium crystal grains forms a large cavity, and the durability of the cathode component 1 may be reduced.
  • the particle size D 50 having a cumulative frequency of 50% is preferably 1.8 ⁇ m or more. As a result, the pinning effect can be made more uniform.
  • the upper limit of the particle size D 50 is not particularly limited, but is, for example, 3.0 ⁇ m or less.
  • the frequency distribution graph of thorium crystal grains has a minimum point in the range of grain size of 2 ⁇ m or more and 3 ⁇ m or less. This can increase the proportion of thorium crystal grains having a grain size of 3 ⁇ m or more.
  • the minimum point is the top of the valley of the frequency distribution graph.
  • the maximum point is the peak of the mountain of the frequency distribution graph.
  • the presence of peaks in the frequency distribution graph indicates that the number of crystal grains having a grain size corresponding to the top of the peaks is large.
  • the presence of valleys in the frequency distribution graph indicates that the number of crystal grains having a grain size corresponding to the bottom of the valley is small.
  • the frequency distribution graph of thorium crystal grains shows that the difference between the frequency of the minimum point in the particle size range of 2 ⁇ m or more and 3 ⁇ m or less in the frequency distribution graph and the frequency of the maximum point closest to the minimum point is 10% or more. It is preferable to have certain points. This indicates that the frequency distribution graph has large valleys. The large troughs can increase the number of thorium crystal grains having a similar grain size. The pinning effect can be made uniform by approximating the grain size of the thorium crystal grains.
  • the cathode component 1 does not have a recrystallized structure. Before recrystallization, it is important to control the grain size of thorium crystal grains, the grain size of tungsten crystal grains, and the like. Thereby, even if it has a recrystallized structure, abnormal grain growth of tungsten crystal grains can be suppressed.
  • the cathode component of the embodiment is a cathode component before recrystallization.
  • the recrystallization structure is a structure in which strain within the crystal (internal stress) is reduced by heat treatment at the recrystallization temperature.
  • the recrystallization temperature of the tungsten alloy containing thorium is 1300K or more and 2000K or less (1027°C or more and 1727°C or less).
  • the cathode component 1 needs to be formed by processing for forming the tip portion 3. In addition, it is necessary to perform processing for adjustment in order to adjust the wire diameter W of the body portion 2.
  • the strain caused by these processes can be relaxed by the recrystallization heat treatment. Recrystallization formed at a temperature of 1300 K or more and 2000 K or less is called primary recrystallization.
  • the primary recrystallization is accompanied by grain growth as compared with that before the heat treatment.
  • Recrystallization formed at a temperature of over 2000 K is called secondary recrystallization.
  • Secondary recrystallization causes more grain growth than primary recrystallization.
  • the grain size of the secondary recrystallization is 30 times or more larger than that before the heat treatment. Therefore, the presence or absence of recrystallization can be judged from the grain size.
  • the discharge lamp is turned on, the temperature of the cathode electrode rises to over 2000°C. Therefore, the cathode component 1 has a recrystallized structure. When it is used for a long time, the high temperature state continues, so that it is an environment where the particles are more likely to grow.
  • the secondary recrystallized crystal grains are 30 times or more larger than those before the heat treatment. Therefore, the presence or absence of the recrystallized structure can be judged from the grain size.
  • the grain size before recrystallization is controlled, so grain growth can be suppressed. As a result, the flicker life of the discharge lamp can be extended.
  • the conventional discharge lamp causes a flicker phenomenon after about half the guaranteed life required for the discharge lamp. Upon investigating the cause of this, it was found that abnormal grain growth occurs in the tungsten crystal grains of the cathode part for the discharge lamp after a certain period of time.
  • the discharge lamp cathode component of the embodiment can suppress the occurrence of abnormal grain growth of tungsten crystal grains. As a result, it is possible to provide a discharge lamp cathode component having a long life.
  • FIG. 5 is a diagram showing a structural example of a discharge lamp.
  • FIG. 5 shows the cathode component 1, the anode component 6, the electrode support rod 7, and the glass tube 8.
  • Cathode component 1 is connected to one electrode support rod 7.
  • the anode component 6 is connected to another electrode support rod 7.
  • the connection is made by brazing or the like.
  • the cathode part 1 and the anode part 6 are arranged to face each other in the glass tube 8 and are sealed together with a part of the electrode support rod 7.
  • the inside of the glass tube 8 is kept in vacuum.
  • the cathode part 1 can be applied to both low-pressure discharge lamps and high-pressure discharge lamps.
  • the low-pressure discharge lamps include various arc discharge type discharge lamps used for general lighting, special lighting used for roads and tunnels, paint curing equipment, UV curing equipment, sterilization equipment, light cleaning equipment for semiconductors, etc.
  • To be High-pressure discharge lamps include water and sewage treatment equipment, general lighting, outdoor lighting such as stadiums, UV curing equipment, exposure equipment such as semiconductors and printed circuit boards, wafer inspection equipment, high-pressure mercury lamps such as projectors, metal halide lamps, and ultra-high pressure. Examples thereof include a mercury lamp, a xenon lamp, and a sodium lamp.
  • the discharge lamp is used in various devices such as a lighting device, a video projection device, and a manufacturing device.
  • the cathode component of the embodiment has excellent durability and is suitable for a high pressure discharge lamp.
  • the output of the discharge lamp is, for example, 100 W to 10 kW.
  • a discharge lamp with an output of less than 1000 W is a low-pressure discharge lamp, and a discharge lamp with an output of 1000 W or more is a high-pressure discharge lamp.
  • Each discharge lamp has a guaranteed life set according to the application.
  • Flicker life is one of the guaranteed lifetimes.
  • the flicker phenomenon is a phenomenon in which the output of the discharge lamp fluctuates as described above, and the output decreases despite the application of a voltage that makes the output of the discharge lamp 100%.
  • ⁇ Discharge lamps for digital cinema are configured with discharge lamps with an output of 1 kW or more and 7 kW or less. Select the discharge lamp output according to the screen size. When the screen size is 6 m, the output is 1.2 kW. When the screen size is 15 m, the output is 4 kW. When the screen size is 30 m, the output is 7 kW.
  • the rated life of a discharge lamp with an output of 1.2 kW is set to about 3000 hours.
  • the rated life of a discharge lamp with an output of 4 kW is set to about 1000 hours.
  • the rated life of the discharge lamp having an output of 7 kW is set to about 300 hours.
  • the life of the discharge lamp for digital cinema becomes shorter as the output increases. As described above, the life of the discharge lamp varies depending on the application and use conditions.
  • the cathode component of the embodiment can suppress abnormal grain growth of tungsten crystal grains during use of the discharge lamp. Therefore, the occurrence of the flicker phenomenon can be suppressed.
  • the cathode component of the embodiment is suitable for a discharge lamp for digital cinema. Although a discharge lamp for digital cinema is illustrated here, the same applies to other uses.
  • the method for manufacturing the cathode component of the embodiment is not particularly limited as long as the cathode component having the above-described configuration can be formed, but the following method can be mentioned as a method for manufacturing the cathode component with high yield.
  • a method for manufacturing a cathode component for a discharge lamp is a method of forming a mixed powder by mixing a tungsten source powder and a thorium source powder, a step of forming a molded body using the mixed powder, and a pre-sintering of the molded body.
  • the method includes a step of sintering to form a pre-sintered body, and a step of sintering the pre-sintered body by electric current sintering.
  • the frequency distribution graph of the particle size distribution of the tungsten source powder has a plurality of peaks including a first peak and a second peak which are adjacent to each other, and a peak-to-peak distance between the first peak and the second peak is It is preferably 10 ⁇ m or more.
  • a mixed powder of a large powder and a small powder can be formed.
  • the mixed powder has the small powder at the grain boundary of the large powder.
  • the grain boundary size between the tungsten crystal grains can be made uniform.
  • Thorium crystal grains exist at grain boundaries between tungsten crystal grains. By making the grain boundary sizes of the tungsten crystal grains uniform, the size of the thorium crystal grains existing at the grain boundaries can be adjusted.
  • Each of the frequencies of a plurality of peaks including the first peak and the second peak is preferably 2% or more. This can improve the effect of making the grain boundary size uniform.
  • the frequency distribution graph has a first tungsten source powder having a first peak in a particle size range of less than 10 ⁇ m, and the frequency distribution graph has a particle size range of 10 ⁇ m or more. It is preferred to mix with a second tungsten source powder having a second peak to form a mixed tungsten powder. 30% by mass or more and 50% by mass or less of the mixed tungsten powder is the first tungsten source powder (tungsten source powder having a small particle size), and the balance is the second tungsten source powder (tungsten source powder having a large particle size). Preferably.
  • the frequency distribution graph of the particle size distribution of the first tungsten source powder preferably has a first peak having a frequency of 4% or more and 6% or less in a particle size range of 4 ⁇ m or more and 7 ⁇ m or less.
  • the frequency distribution graph of the second tungsten source powder preferably has a second peak having a frequency of 6% or more and 8% or less in a particle size range of 20 ⁇ m or more and 50 ⁇ m or less.
  • the particle size distribution of the tungsten source powder is measured using Microtrac 9320-X100. This device can measure the particle size by the laser diffraction method. The peak position and frequency can be read from the particle size distribution obtained by the measurement.
  • the thorium source powder can adjust the amount of thorium in the tungsten alloy by using a thorium component that becomes thorium oxide (ThO 2 ) for example.
  • the thorium source powder and the tungsten source powder can be mixed using, for example, a wet method or a dry method.
  • a liquid component is evaporated from a solution containing thorium nitrate and tungsten powder, and heated at a temperature of 400°C to 900°C in an air atmosphere to decompose the thorium component into thorium oxide.
  • the tungsten powder containing the thorium oxide powder can be formed.
  • thorium oxide powder is pulverized and mixed in a ball mill.
  • the aggregated thorium oxide powder can be loosened, and the aggregation of the thorium oxide powder can be reduced.
  • a small amount of tungsten powder may be added during the mixing step.
  • tungsten powder is added so that the desired concentration of thorium oxide is obtained.
  • a mixed powder of thorium oxide powder and tungsten powder is put in a mixing container, and the mixing container is rotated to uniformly mix.
  • the mixing container has a cylindrical shape and is rotated in the circumferential direction, whereby smooth mixing can be performed.
  • the tungsten powder containing the thorium oxide powder can be prepared.
  • the tungsten powder containing the thorium oxide powder can be prepared by the wet method or the dry method as described above.
  • the wet method is preferable. Since the dry method mixes while rotating the mixing container, the raw material powder and the container are rubbed with each other and impurities are easily mixed.
  • the content of the thorium oxide powder is preferably 0.5% by mass or more and 3% by mass or less.
  • the thorium oxide powder can easily penetrate into the gap between the tungsten powders. This makes it easy to control the grain sizes of the tungsten crystal grains and thorium crystal grains.
  • the molded body is formed using, for example, tungsten powder containing thorium oxide powder.
  • a binder may be used if necessary.
  • the molded body has, for example, a cylindrical shape having a diameter of 5 mm or more and 50 mm or less. The length of the molded body is arbitrary.
  • Pre-sintering is preferably performed at a temperature of 1250°C or higher and 1500°C or lower.
  • the temperature becomes 2100° C. or higher and 2500° C. or lower. If the temperature is lower than 2100°C, sufficient densification cannot be achieved and the strength may be reduced. If it exceeds 2500° C., the thorium crystal grains and the tungsten crystal grains may grow too much to obtain a desired crystal structure.
  • a sintered body (ingot) having a thorium-containing tungsten alloy can be obtained. If the pre-sintered body has a cylindrical shape, the sintered body also has a cylindrical shape. An example in which the sintered body is a columnar sintered body having a cylindrical shape will be described below.
  • the above manufacturing method may further include a first processing step and a second processing step.
  • the ingot is processed by at least one processing selected from the group consisting of forging processing, rolling processing, and extrusion processing, and, for example, the wire diameter W of the ingot is adjusted.
  • the wire diameter W can be reduced by these processes. Therefore, the pores in the cylindrical sintered body can be reduced.
  • the first processing step is preferably forging or extrusion. In the forging process or the extrusion process, it is easy to process the entire circumference of the cylindrical sintered body, so that the effect of reducing pores is high.
  • Forging is the process of hitting a cylindrical sintered body with a hammer to apply pressure.
  • Rolling is a method of processing while sandwiching the sintered body with two or more rollers.
  • Extrusion processing is a method of pressing strongly and extruding through a die hole.
  • Forging process is hit with a hammer, so it is easy for partial variation in crystal orientation.
  • the stress when passing through the die is strong, and thus the crystal orientations in the central part and the surface part are likely to differ.
  • the stress from the roller can be adjusted, so that the crystal orientation can be easily controlled.
  • the processing rate of the first processing step is preferably 10% or more and 30% or less. If the processing rate is less than 10%, the effect of reducing pores is small. When the processing rate exceeds 30%, it becomes difficult to control the crystal orientation.
  • the first processing step may be carried out in plural times as long as the processing rate is in the range of 10% or more and 30% or less.
  • the processing rate is [(AB)/A] ⁇ 100%. , Required by.
  • the fact that the processing rate of the first processing step is 10% or more and 30% or less is determined as the cross-sectional area A of the cylindrical sintered body (ingot) before the first processing step.
  • the second processing step is, for example, rolling. Rolling makes it easy to control the crystal orientation. Rolling is a method of reducing the cross-sectional area while sandwiching it with a plurality of rollers. The crystal orientation can be controlled by processing only by rolling. The second processing step is performed after the first processing step.
  • the processing rate of rolling in the second processing step is 30% or more and 70% or less, preferably 40% or more and 70% or less. That the processing rate of the second processing step is 30% or more and 70% or less is obtained by setting the sectional area A of the cylindrical sintered body after the first processing step as the sectional area A.
  • the processing rate is controlled by setting the sectional area after the first processing step as the sectional area A. If the processing rate is within the range of 30% or more and 70% or less, the processing may be performed once or may be divided into two or more times. If the processing rate is less than 30% or more than 70%, the desired crystal grains cannot be obtained.
  • the first working step and the second working step are preferably cold working.
  • Cold working is a method of working an object at a temperature equal to or lower than the recrystallization temperature. Processing in a heated state above the recrystallization temperature is called hot working. If it is hot working, the cylindrical sintered body is recrystallized. Cold working does not recrystallize. It is important to control the crystal grains with a structure that does not recrystallize.
  • the cylindrical sintered body with a wire diameter of 2 mm or more and 35 mm or less formed by the above process is cut into a required length.
  • the step of forming the tapered tip portion 3 is performed.
  • the tip portion 3 is processed by cutting the tip portion 3 into a predetermined taper shape. If necessary, surface polishing is performed so that the surface roughness Ra is 5 ⁇ m or less.
  • the cathode component of the embodiment can be manufactured by the above steps.
  • the discharge lamp can be manufactured as follows. First, the cathode component 1 is connected to the electrode support rod 7. The connection can be made by brazing or the like. A part in which the anode part 6 is connected to the electrode support rod 7 is prepared. The cathode component 1 and the anode component 6 are arranged and fixed so as to face each other in the glass tube 8, and are sealed together with a part of the electrode support rod 7. The inside of the glass tube 8 is evacuated. During the process of manufacturing the discharge lamp, if necessary, heat treatment at a recrystallization temperature of the cathode component or higher may be performed.
  • Example 1 is a table for explaining the tungsten source powder and the thorium source powder.
  • the tungsten source powder includes a first tungsten powder having a particle size distribution showing a frequency distribution graph having a first peak and a second tungsten powder having a particle size distribution showing a frequency distribution graph having a second peak. It is a mixed tungsten powder. Table 1 shows the content of the first tungsten powder and the content of the second tungsten powder in the mixed tungsten powder, and the peak particle diameter and the peak frequency of the first and second tungsten powders.
  • the mixed powder was formed by evaporating a liquid component from a solution containing thorium nitrate and tungsten powder and heating it in an air atmosphere at a temperature of 400° C. or higher and 900° C. or lower to decompose the thorium component into thorium oxide.
  • the content of the thorium source powder is ThO 2 conversion.
  • the thorium source powder has an average particle size of 3 ⁇ m or less.
  • the content of the thorium source powder is 0.5% by mass or more and 2.6% by mass or less in terms of ThO 2
  • the first tungsten source powder of the mixed tungsten powder is 40 mass% or more and 50 mass% or less
  • the content of the second tungsten source powder is 50 mass% or more and 60 mass% or less
  • the frequency distribution graph of the tungsten source powder is 8 ⁇ m or less. It can be seen that there is a first peak in the particle size range and a second peak in the particle size range of 20 ⁇ m or more, and the peak frequencies are all 3% or more.
  • a molded body was formed using the mixed powder.
  • the compact was sintered by pre-sintering to form a pre-sintered body.
  • the pre-sintered body was sintered by electric current sintering to prepare a columnar sintered body (ingot).
  • Table 2 is a table for explaining the pre-sintering and the electric current sintering.
  • Table 3 is a diagram for explaining the first processing step and the second processing step. Both the first working step and the second working step are cold working.
  • the cold-worked cylindrical sintered body was processed by cutting. Further, a tapered tip portion was formed on the end portion of the cut columnar sintered body. The taper angle of the tip is 60 degrees or more and 80 degrees or less.
  • Table 4 is a table for explaining the size of the cathode component.
  • the manufactured cathode part was analyzed by EBSD analysis to create a crystal grain map of tungsten crystal grains and a crystal grain map of thorium crystal grains. Since the measurement conditions and the like are as described in the embodiment, the description thereof will be omitted here.
  • FIG. 3 is a diagram showing a cumulative distribution graph of thorium crystal grains of Example 1 and Comparative Example 1.
  • FIG. 4 is a diagram showing a frequency distribution graph of thorium crystal grains of Example 1 and Comparative Example 1.
  • the solid lines in FIGS. 3 and 4 show Example 1, and the dotted lines show Comparative Example 1.
  • the grain size D 90 and the grain sizes D 50 and D 100 of the thorium crystal grains were calculated.
  • the presence/absence of a minimum point the presence/absence of a minimum point in the particle size range of 2 ⁇ m or more and 3 ⁇ m or less, and the frequency of the minimum point in the particle size range of 2 ⁇ m or more and 3 ⁇ m or less and the closest point to the minimum point. It was confirmed whether or not there was a portion where the difference from the frequency of the maximum point was 10% or more.
  • the average grain size of the tungsten crystal grains was calculated using the crystal grain map of the tungsten crystal grains.
  • Table 5 is a table for explaining the thorium crystal grain and the tungsten crystal grain.
  • the grain size D 90 of the thorium crystal grains was 3.0 ⁇ m or more and 3.9 ⁇ m or less, and the grain size D 50 was 1.8 ⁇ m or more and 4.0 ⁇ m or less.
  • D 100 was 4.8 ⁇ m or less.
  • the average grain size of the tungsten crystal grains was 4 ⁇ m or more and 7.8 ⁇ m or less.
  • the frequency distribution graph has a minimum point in the range of particle size of 2 ⁇ m or more and 3 ⁇ m or less.
  • the difference between the frequency of the minimum point in the range of the particle size of 2 ⁇ m or more and 3 ⁇ m or less and the frequency of the maximum point closest to the minimum point was 10% or more.
  • Comparative Example 1 although there was a minimum value in the frequency distribution graph of thorium crystal grains, other values were out of the range. Further, the grain size D 50 of the tungsten crystal grains was 20 ⁇ m or less in all cases.
  • the durability of the cathode parts for discharge lamps was evaluated by a durability test.
  • a discharge lamp was produced using the cathode part for a discharge lamp.
  • the durability test was performed by a lighting test, and the flicker life of the discharge lamp was measured.
  • the lamp voltage during lighting is 40V, and the lamp voltage during non-lighting is 20V.
  • the lighting state was set to 3 hours and the non-lighting state was set to 2 hours, and the lighting state and the non-lighting state were alternately repeated. It was defined that flicker occurred when the deviation of the lamp voltage in the lighting state or the non-lighting state was 1 V or more.
  • the total lighting time until the occurrence of flicker was defined as the flicker life.
  • the average grain size ( ⁇ m) of the tungsten crystal grains was measured after 800 hours.
  • the average particle diameter D50 was measured by using a cross-section in the side surface direction of the tip portion and measuring a portion located 0.5 mm from the tip. The results are shown in Table 6.
  • the discharge lamps using the cathode parts of Examples 1 to 7 had a longer life than the discharge lamps using the cathode parts of Comparative Example 1. This is because the pinning effect of the thorium crystal grains can be uniformly exhibited and the coarsening of the tungsten crystal grains can be suppressed. Further, by using the tungsten source powder having a plurality of peaks in the frequency distribution graph, the particle size distribution of thorium crystal grains can be controlled.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Discharge Lamp (AREA)
  • Powder Metallurgy (AREA)

Abstract

Un composant de cathode pour lampes à décharge selon la présente invention comprend : une partie de corps qui a un diamètre de fil de 2 mm à 35 mm (inclus) ; et une partie de pointe qui est effilée à partir de la partie de corps. Ce composant de cathode contient un alliage de tungstène qui contient de 0,5 % en masse à 3 % en masse de thorium en termes de ThO2. Si une analyse de diffraction par rétrodiffusion d'électrons est effectuée sur une région qui comprend le centre d'une section transversale qui passe à travers le centre de la partie de corps et s'étend le long de la direction de la longueur de la partie de corps, et qui a une surface unitaire de 90 µm × 90 µm, la carte de grains cristallins obtenue par cette analyse de diffraction par rétrodiffusion d'électrons comprend des grains de cristaux de tungstène contenant du tungstène et des grains cristallins de thorium contenant du thorium. Par rapport au graphique de distribution cumulative de la distribution de taille de particule de la pluralité de grains cristallins de thorium dans la carte de grains cristallins, la taille de particule à la fréquence cumulative de 90 % est supérieure ou égale à 3,0 µm.
PCT/JP2020/006284 2019-02-18 2020-02-18 Composant de cathode pour lampes à décharge, lampe à décharge et procédé de production d'un composant de cathode pour lampes à décharge WO2020171065A1 (fr)

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JP2021502027A JP7098812B2 (ja) 2019-02-18 2020-02-18 放電ランプ用カソード部品、放電ランプ、および放電ランプ用カソード部品の製造方法

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Citations (6)

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Publication number Priority date Publication date Assignee Title
WO2011108288A1 (fr) * 2010-03-05 2011-09-09 パナソニック株式会社 Électrode pour lampe à décharge, lampe à décharge à haute tension, unité de lampe et dispositif d'affichage d'images du type projecteur
WO2013122081A1 (fr) * 2012-02-15 2013-08-22 株式会社 東芝 Composant cathodique pour lampe à décharge
WO2014006779A1 (fr) * 2012-07-03 2014-01-09 株式会社 東芝 Pièce en alliage de tungstène, et lampe à décharge, tube de transmission et magnétron la comportant
WO2014021154A1 (fr) * 2012-07-31 2014-02-06 東芝マテリアル株式会社 Électrode négative destinée à une lampe à décharge et son procédé de fabrication
JP2014063655A (ja) * 2012-09-21 2014-04-10 Orc Manufacturing Co Ltd 放電ランプ用電極の製造方法
WO2018213858A2 (fr) * 2017-05-23 2018-11-29 Plansee Se Matériau de cathode

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DE19738574A1 (de) * 1997-09-04 1999-03-11 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Elektrode und Verfahren sowie Vorrichtung zur Herstellung derselben
JP4486163B1 (ja) * 2008-12-08 2010-06-23 株式会社アライドマテリアル タングステン電極材料およびタングステン電極材料の製造方法
CN112272860B (zh) * 2018-11-19 2023-11-07 株式会社东芝 放电灯用阴极部件及放电灯

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011108288A1 (fr) * 2010-03-05 2011-09-09 パナソニック株式会社 Électrode pour lampe à décharge, lampe à décharge à haute tension, unité de lampe et dispositif d'affichage d'images du type projecteur
WO2013122081A1 (fr) * 2012-02-15 2013-08-22 株式会社 東芝 Composant cathodique pour lampe à décharge
WO2014006779A1 (fr) * 2012-07-03 2014-01-09 株式会社 東芝 Pièce en alliage de tungstène, et lampe à décharge, tube de transmission et magnétron la comportant
WO2014021154A1 (fr) * 2012-07-31 2014-02-06 東芝マテリアル株式会社 Électrode négative destinée à une lampe à décharge et son procédé de fabrication
JP2014063655A (ja) * 2012-09-21 2014-04-10 Orc Manufacturing Co Ltd 放電ランプ用電極の製造方法
WO2018213858A2 (fr) * 2017-05-23 2018-11-29 Plansee Se Matériau de cathode

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