WO2020105644A1 - Composant de cathode pour lampe à décharge, et lampe à décharge - Google Patents

Composant de cathode pour lampe à décharge, et lampe à décharge

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Publication number
WO2020105644A1
WO2020105644A1 PCT/JP2019/045311 JP2019045311W WO2020105644A1 WO 2020105644 A1 WO2020105644 A1 WO 2020105644A1 JP 2019045311 W JP2019045311 W JP 2019045311W WO 2020105644 A1 WO2020105644 A1 WO 2020105644A1
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WO
WIPO (PCT)
Prior art keywords
orientation
degrees
less
tungsten
crystal
Prior art date
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PCT/JP2019/045311
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English (en)
Japanese (ja)
Inventor
雅恭 溝部
斉 青山
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
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
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 CN201980037894.2A priority Critical patent/CN112272860B/zh
Priority to JP2020557563A priority patent/JP6972383B2/ja
Publication of WO2020105644A1 publication Critical patent/WO2020105644A1/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
    • 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

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 equipment, ultraviolet (UV) curing equipment, sterilization equipment, light cleaning equipment 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 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.
  • consumption of electrodes of the discharge lamp affects lamp life and flicker of emitted light.
  • PWM pulse width modulation
  • the cathode part manufactured by using the above technique was applied with a voltage in a state where the cathode part was energized and heated, and the emission current density (mA / mm 2 ) after 10 hours and after 100 hours 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 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 part includes a tungsten alloy containing 0.5% by mass or more and 3% by mass or less of ThO 2 in terms of ThO 2 , and within 1 mm from the center in the cross section passing through the center of the body and along the length direction of the body.
  • 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 portion 2, a tip portion 3, a center 4, a line W of the body portion 2, and a length T of the body portion 2.
  • FIG. 2 is a view showing an example of a cross section in the length direction of the center 4 of the body portion 2.
  • 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 catho
  • the discharge lamp cathode component may be simply referred to as “cathode component”.
  • 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 indicates the largest diameter. If the wire diameter W of the body portion 2 is less than 2 mm, the discharge lamp may be insufficient in light emission. If 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 becomes the tip 3.
  • the tip 3 has an acute-angled shape in a cross section of the cathode component 1 in the direction a.
  • 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 tip portion 3 has a tapered shape, it is possible to efficiently discharge between the pair of electrode parts of the discharge lamp.
  • 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 deteriorate. 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 cathode component 1 is located within 1 mm from the center 4 and has a unit area of 90 ⁇ m ⁇ 90 ⁇ m in a cross section 5 passing through the center 4 of the body 2 and along the length T direction (direction a) of the body 2.
  • EBSD electron backscattering diffraction
  • the area ratio of the tungsten phase having a crystallographic orientation of -15 degrees or more and 15 degrees or less is the highest in the inverse pole figure (IPF) map in the length direction. high.
  • EBSD irradiates a crystal sample with an electron beam.
  • the electrons are diffracted and emitted from the sample as reflected electrons.
  • the crystal orientation can be measured from the projected pattern.
  • X-ray diffraction X-ray diffraction
  • EBSD can measure the crystal orientation of individual crystals.
  • An analysis method similar to EBSD is sometimes called electron backscattering pattern (EBSP) analysis.
  • EBSD analysis is 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 are as follows: electron beam acceleration voltage 20 kV, irradiation current 12 nA, sample tilt angle 70 degrees, measurement area unit area 90 ⁇ m ⁇ 90 ⁇ m, measurement position within 1 mm from center 4, measurement interval 0.3 ⁇ m / step. including.
  • the cross section 5 is the 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 measurement point is the cross section 5 in the length T direction (direction a) that passes through the center 4 of the body 2.
  • the center 4 of the body portion 2 is a point where a straight line passing through the midpoint of the line W of the body portion 2 and a straight line passing through the midpoint of the length T intersect.
  • the cross section 5 is a cross section that passes through the center 4 and is horizontal in the length T direction (direction a).
  • the crystal orientation indicates the direction using the basic vector.
  • the notation consisting of a combination of square brackets ([]) and the numbers between the square brackets indicates only a specific crystal orientation.
  • a notation consisting of a combination of angle brackets ( ⁇ >) and a number sandwiched between angle brackets indicates a specific crystal orientation and an equivalent direction.
  • the ⁇ 101> direction indicates that the direction equivalent to [101] is included.
  • the fact that the preferential orientation of the tungsten phase in the direction a is the ⁇ 101> orientation means that the ⁇ 101> orientation has the highest proportion of all the crystal orientations.
  • the IPF map is a crystal orientation map.
  • the ratio of the area deviated from the predetermined crystal orientation can be obtained by the area ratio.
  • the IPF map can be obtained according to the above-mentioned EBSD measurement method. By color mapping, the area ratio can be easily obtained by image analysis.
  • the preferred orientation of the tungsten phase is ⁇ 101> orientation.
  • Abnormal grain growth is the coarsening of tungsten crystals during the manufacturing process or use of the discharge lamp.
  • Thorium is an emitter material. Thorium is distributed at grain boundaries between tungsten crystals. When the tungsten crystal grows abnormally, the distribution state of thorium changes. This reduces the flicker life and the illuminance maintenance rate. The flicker life is the time until the flicker phenomenon occurs.
  • the cathode part for a discharge lamp of the embodiment suppresses abnormal grain growth of tungsten crystals.
  • Abnormal grain growth occurs not only during the manufacturing process of the cathode component but also during use of the discharge lamp.
  • Coarse grains are formed during use of the discharge lamp after incorporation of the cathode component, even though the cathode component prior to incorporation into the discharge lamp does not have the coarse grains formed by abnormal grain growth.
  • the area ratio of the tungsten phase having a crystal orientation with an orientation difference of ⁇ 15 degrees or more and 15 degrees or less with respect to the orientation is preferably 50% or more.
  • the same effect as the ⁇ 101> orientation can be obtained.
  • the area ratio of the tungsten phase having a crystal orientation with an orientation difference of less than ⁇ 15 degrees with respect to the ⁇ 101> orientation is less than 50%, the effect of improving the characteristics may be insufficient. Further, the effect of suppressing abnormal grain growth can be enhanced by controlling the area ratio of the tungsten phase in a minute region having a unit area of 90 ⁇ m ⁇ 90 ⁇ m. This can prolong the flicker life.
  • the orientation difference with respect to the ⁇ 101> orientation deviates from the range of ⁇ 15 degrees, the proportion of the tungsten phase having a crystal orientation other than the desired crystal orientation increases.
  • the upper limit of the area ratio is preferably 80% or less. If it exceeds 80%, it may be difficult to control the crystal orientation in the direction b perpendicular to the cross section 5.
  • the area ratio of the tungsten phase having a crystal orientation with an orientation difference of ⁇ 10 degrees or more and 10 degrees or less with respect to the ⁇ 101> orientation is 35% or more, and further 50% or more. preferable.
  • the area ratio of the tungsten phase having a crystal orientation having an orientation difference within ⁇ 10 degrees with respect to the ⁇ 101> orientation is 35% or more, which means that the area ratio of the tungsten phase having a crystal orientation close to the ⁇ 101> orientation is high. Indicates that.
  • the area ratio is preferably 65% or less. Thereby, abnormal grain growth can be further suppressed.
  • the area ratio of the tungsten phase having a crystal orientation with an orientation difference of ⁇ 5 degrees or more and 5 degrees or less with respect to the ⁇ 101> orientation is preferably 10% or more, and more preferably 15% or more.
  • the area ratio is preferably 30% or less.
  • the area ratio of the tungsten phase having a crystal orientation within ⁇ 15 degrees, ⁇ 10 degrees, and ⁇ 5 degrees with respect to the ⁇ 101> orientation satisfies the respective ranges.
  • the area ratios are preferably larger in the order of “ ⁇ 5 degrees or less” ⁇ “ ⁇ 10 degrees or less” ⁇ “ ⁇ 15 degrees or less”.
  • the EBSD analysis is performed on a region that passes through the center 4 of the body portion 2 and is located within 1 mm from the center in the cross-section 5 in the length T direction (direction a) and has a unit area of 90 ⁇ m ⁇ 90 ⁇ m, it is perpendicular to the cross-section 5.
  • the area ratio of the tungsten phase having a crystal orientation with an orientation difference of ⁇ 15 degrees or more and 15 degrees or less with respect to the ⁇ 111> orientation is 15% or more and 50% or less.
  • the same effect as the ⁇ 111> orientation can be obtained. Even if the crystal orientation is within ⁇ 15 degrees with respect to the ⁇ 111> orientation, if the area ratio is less than 15% or more than 50%, the effect of improving the characteristics may be insufficient. Therefore, the area ratio is preferably 15% or more and 50% or less, and more preferably 18% or more and 40% or less.
  • the effect of suppressing abnormal grain growth can be enhanced by controlling the area ratio of the tungsten phase having a predetermined crystal orientation in a minute region having a unit area of 90 ⁇ m ⁇ 90 ⁇ m. This can prolong the flicker life.
  • the area ratio of the tungsten phase having a crystal orientation with an orientation difference of ⁇ 10 degrees or more and 10 degrees or less with respect to the ⁇ 111> orientation is 5% or more and 30% or less. Further, it is preferably within the range of 10% or more and 25% or less.
  • the area ratio of the tungsten phase having a crystal orientation with an orientation difference of ⁇ 5 degrees or more and 5 degrees or less with respect to the ⁇ 111> orientation is 1% or more and 15% or less. Further, it is preferably 3% or more and 10% or less.
  • the area ratios of the tungsten phases having crystal orientations within ⁇ 15 degrees, ⁇ 10 degrees, and ⁇ 5 degrees with respect to the ⁇ 111> orientation satisfy the above ranges. It is preferable that the respective area ratios are large in the order of "within ⁇ 5 degrees" ⁇ "within ⁇ 10 degrees” ⁇ "within ⁇ 15 degrees".
  • the larger order means that there is a tungsten phase having a crystallographic orientation having an orientation difference within ⁇ 5 degrees, ⁇ 6 degrees to ⁇ 10 degrees, and ⁇ 11 degrees to ⁇ 15 degrees. ..
  • the occurrence of abnormal grain growth can be suppressed by controlling the area ratio of each.
  • the direction b in FIG. 2 is a direction perpendicular to the cross section 5 in the length T direction (direction a).
  • a cross section 5 in the length T direction (direction a) is a measurement cross section of the crystal orientation difference.
  • the crystal orientation most strongly oriented in the length T direction (direction a) is the ⁇ 101> orientation.
  • the grain growth can be further suppressed by allowing the tungsten phase having a crystal orientation close to the ⁇ 111> orientation to exist in the vertical direction b of the cross section 5 at a predetermined ratio.
  • the control of the crystal orientation and its area ratio differs depending on the direction. Thereby, grain growth can be suppressed and the life of the cathode component can be extended.
  • the crystal orientation By controlling the crystal orientation in this manner, for example, elongated crystal grains can be formed. By forming elongated crystal grains, grain growth can be suppressed.
  • the average aspect ratio of crystal grains is 2 or more.
  • the longest diagonal line of the crystal shown in the image observed with the laser microscope or the SEM is the major axis.
  • the length extended vertically from the center of the major axis is defined as the minor axis.
  • (Major axis + minor axis) / 2 particle size. This operation is performed for 10 or more grains, and the average value is defined as the average grain size.
  • Major axis / minor axis aspect ratio.
  • the average value of 10 or more grains is defined as the average aspect ratio.
  • the crystal with all the contours is measured.
  • the average grain size of the tungsten crystal is preferably 20 ⁇ m or less. When the average particle size exceeds 20 ⁇ m, it becomes difficult to control the orientation ratio (area ratio) in a region having a unit area of 90 ⁇ m ⁇ 90 ⁇ m. If the average particle size is large, the durability is likely to decrease due to the particle growth. Thorium is distributed at grain boundaries between tungsten crystals. By setting the average grain size of the tungsten crystal to 20 ⁇ m or less, the distribution state of the emitter material can be made uniform. This can improve the discharge characteristics.
  • the average grain size of the tungsten crystal is obtained using the crystal grain map when performing EBSD analysis.
  • the crystal grain map of the tungsten crystal is the same crystal grain when the measurement points of the tungsten phase having the crystal orientations with the crystal orientation difference within ⁇ 5 degrees in the area of the unit area 90 ⁇ m ⁇ 90 ⁇ m exist continuously. Identified and displayed as.
  • the average particle size is calculated from the area of the identified crystal particles in a region having a unit area of 90 ⁇ m ⁇ 90 ⁇ m.
  • the particle size is equivalent to a circle.
  • the boundary of the region having a unit area of 90 ⁇ m ⁇ 90 ⁇ m is calculated as a crystal grain boundary.
  • the average particle diameter is the median diameter (average particle diameter D 50 ). That is, it is the cumulative particle size.
  • the average grain size D 50 of the tungsten crystal is preferably 20 ⁇ m or less, more preferably 15 ⁇ m or less.
  • the cross-section 5 is the measurement point of the average grain size D 50 of the tungsten crystal. It is preferable that the average grain diameter D 50 of the tungsten crystal is 20 ⁇ m or less regardless of where the cross section 5 and the cross section in the wire diameter W direction (direction b) are measured.
  • the particle size D 90 when the cumulative frequency ratio from the small diameter side in the particle size distribution of the tungsten crystal is 90% is preferably 25 ⁇ m or less.
  • the method of determining the particle size D 90 is the same as the average particle size D 50 . It is preferable that D 90 ⁇ D 50 ⁇ 7 ⁇ m. The fact that the difference between the particle size D 90 and the average particle size D 50 is 7 ⁇ m or less indicates that there is no variation in particle size and there are no coarse particles.
  • the lower limit of the average particle diameter D 50 of the tungsten crystal is not particularly limited, but it is preferably 3 ⁇ m or more. When the average particle size D 50 is smaller than 3 ⁇ m, it becomes difficult to control the difference from the particle size D 90 to 7 ⁇ m or less.
  • the grain size D 90 is also measured using the crystal grain map for which the average grain size D 50 is obtained.
  • the median diameter (average particle diameter D 50 ) of the thorium crystal is preferably 3 ⁇ m or less.
  • the average grain size of the thorium crystal is also obtained by using the crystal grain map of EBSD similarly to the tungsten crystal.
  • the crystal grain map of the thorium crystal is the same crystal grain when the measurement points of the tungsten phase having the crystal orientation with the crystal orientation difference within ⁇ 2 degrees within the unit area of 90 ⁇ m ⁇ 90 ⁇ m exist continuously. It is identified and displayed.
  • the grain size D 90 of the thorium crystal is preferably 5 ⁇ m or less.
  • the difference between the grain size D 90 of the thorium crystal and the average grain size D 50 is preferably 2 ⁇ m or less.
  • D 90 ⁇ D 50 ⁇ 2 ⁇ m it means that the variation in the grain size of the thorium crystal is small.
  • the average particle diameter D 50 of the thorium crystal is preferably 0.01 ⁇ m or more. If it is too small, evaporation may be faster.
  • the tungsten crystal of the cathode part 1 does not have a recrystallized structure. It is important to control the crystal orientation and grain size before recrystallization. Thereby, even if it has a recrystallized structure, abnormal grain growth of the tungsten crystal can be suppressed.
  • the cathode component of the embodiment is a cathode component before recrystallization.
  • Recrystallized structure is a structure in which strain in crystal (internal stress) is reduced by heat treatment at 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 to form 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 higher and 2000 K or lower 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 determined 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. If the product is used for a long time, the high temperature condition continues, so the environment is such that grain growth is more likely to occur.
  • the cathode component of the embodiment controls the crystal orientation before recrystallization, so that grain growth can be suppressed. As a result, the flicker life of the discharge lamp can be extended.
  • the flicker life is preferably 800 hours or more.
  • FIG. 3 is a diagram showing a structural example of a discharge lamp.
  • FIG. 3 shows the cathode component 1, the anode component 6, the electrode support rod 7, and the glass tube 8.
  • the cathode part 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 component 1 and the anode component 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.
  • Cathode part 1 can be applied to both low-pressure discharge lamps and high-pressure discharge lamps.
  • 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. Be done.
  • 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. Since the cathode component of the embodiment has excellent durability, it 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 its application.
  • Flicker life is one of the guaranteed lifetimes.
  • the flicker phenomenon is a variation in the output of the discharge lamp as described above, and the output decreases even though the voltage at which the output of the discharge lamp is 100% is applied.
  • Discharge lamps for digital cinema are composed of discharge lamps with an output of 1 kW or more and 7 kW or less. Select the output of the discharge lamp 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 with 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 the usage conditions.
  • the cathode component of the embodiment can suppress abnormal grain growth of tungsten crystals 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 it has the above-mentioned configuration, but the following method can be mentioned as a method for manufacturing the cathode component with good yield.
  • a tungsten alloy powder containing thorium is prepared.
  • the method for preparing the tungsten alloy powder include a wet method and a dry method.
  • the step of preparing a tungsten material powder is carried out.
  • the tungsten material powder include ammonium tungstate (APT) powder, metallic tungsten powder, and tungsten oxide powder. These tungsten material powders may be used alone or in combination of two or more. Ammonium tungstate powder is preferred because it is relatively inexpensive.
  • the tungsten material powder preferably has an average particle size of 5 ⁇ m or less.
  • the ammonium tungstate powder When using ammonium tungstate powder, the ammonium tungstate powder is converted to tungsten oxide powder by heating the ammonium tungstate powder in the air or in an inert atmosphere (nitrogen, argon, etc.) to a temperature of 400 ° C. or higher and 600 ° C. or lower. Let At a temperature of less than 400 ° C., it cannot be sufficiently converted into a tungsten oxide powder, and at a temperature of more than 600 ° C., the particles of the tungsten oxide powder become coarse, which makes it difficult to uniformly disperse it with the thorium oxide powder in the subsequent step. .. Through this step, a tungsten oxide powder is prepared.
  • the step of adding thorium material powder and tungsten oxide powder to the solution is carried out.
  • the thorium material powder include metal thorium powder, thorium oxide powder, and thorium nitrate powder. Of these, thorium nitrate powder is preferred. Thorium nitrate powder is easy to mix uniformly in a liquid.
  • a solution containing the thorium material powder and the tungsten oxide powder is prepared. It is preferable to add it so that the final concentration is the same as or slightly higher than the target concentration of thorium oxide.
  • the thorium material powder preferably has an average particle size of 5 ⁇ m or less.
  • the solution is preferably pure water.
  • the step of evaporating the liquid component of the solution containing the thorium material powder and the tungsten oxide powder is carried out.
  • a decomposition step of heating the powder of thorium material such as thorium nitrate into powder of thorium oxide by heating in an air atmosphere at a temperature of 400 ° C. or higher and 900 ° C. or lower is performed.
  • a mixed powder containing thorium oxide powder and tungsten oxide powder can be prepared.
  • the thorium oxide concentration of the obtained mixed powder containing the thorium oxide powder and the tungsten oxide powder is measured, and when the concentration is low, it is preferable to add the tungsten oxide powder.
  • a step of heating the mixed powder containing the thorium oxide powder and the tungsten oxide powder at a temperature of 750 ° C. or higher and 950 ° C. or lower in a reducing atmosphere such as hydrogen to reduce the tungsten oxide powder to metallic tungsten powder is carried out. ..
  • the tungsten powder containing the thorium oxide powder can be prepared.
  • a method of mixing the metal tungsten powder and the thorium material powder is also effective.
  • the metal tungsten powder is preferably formed by producing a tungsten oxide powder from an ammonium tungstate powder and reducing the obtained tungsten oxide.
  • the obtained tungsten oxide has oxygen deficiency.
  • WO 3 is stable. With oxygen deficiency, WO 3-x , x> 0. Oxygen deficiency causes distortion in the crystal structure.
  • the metallic tungsten powder obtained by reduction in that state has a high effect of suppressing abnormal grain growth.
  • the value of x is preferably in the range of 0.05 ⁇ x ⁇ 0.30.
  • the step of producing the tungsten oxide powder from the ammonium tungstate powder is preferably a step of heating in an inert atmosphere.
  • the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.
  • the heat treatment temperature is preferably in the range of 400 ° C or higher and 600 ° C or lower. If it is less than 400 ° C, the reaction rate is slow and the mass productivity is lowered. If it exceeds 600 ° C, grain growth may be excessive.
  • the step of reducing the WO 3-x powder is preferably performed in a hydrogen-containing atmosphere.
  • the heat treatment temperature is preferably in the range of 600 ° C or higher and 800 ° C or lower. When the heat treatment temperature is lower than 600 ° C, the rate of reduction is slow and the mass productivity is lowered. If it exceeds 800 ° C, grain growth may be excessive.
  • the step of evaporating the liquid component of the solution containing the thorium material powder and the metal tungsten powder is carried out.
  • a decomposition step of heating the sample at a temperature of 400 ° C. or more and 900 ° C. or less in the air atmosphere to change the thorium material powder such as thorium nitrate into the thorium oxide powder is performed.
  • the tungsten powder containing the thorium oxide powder can be prepared.
  • the dry method first prepare thorium oxide powder.
  • a step of pulverizing and mixing the thorium oxide powder with a ball mill is carried out.
  • the aggregated thorium oxide powder can be loosened, and the aggregated thorium oxide powder can be reduced.
  • a small amount of metallic tungsten powder may be added.
  • thorium oxide powder that has been pulverized and mixed to remove agglomerated powder or coarse particles that cannot be completely pulverized. It is preferable to remove aggregated powder or coarse particles having a maximum diameter of more than 10 ⁇ m by sieving.
  • the metal tungsten powder is added so that the desired concentration of thorium oxide is obtained.
  • a mixed powder of thorium oxide powder and metallic tungsten powder is put into a mixing container, and the mixing container is rotated to uniformly mix. At this time, smooth mixing can be achieved by rotating the cylindrical mixing container in the circumferential direction. Through this step, 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 come into contact with each other, and impurities are easily mixed.
  • the content of the thorium oxide powder is 0.5% by mass or more and 3% by mass or less.
  • a compact is prepared using the tungsten powder containing the obtained thorium oxide powder.
  • a binder may be used if necessary.
  • the molded body preferably has a cylindrical shape with a diameter of 7 mm or more and 50 mm or less. The length of the molded body is arbitrary.
  • the pre-sintering is preferably performed at a temperature of 1250 ° C or higher and 1500 ° C or lower. By this step, a pre-sintered body can be obtained.
  • the process of electric current sintering of the pre-sintered body it is preferable to perform the electric current so that the temperature of the sintered body becomes 2100 ° C. or higher and 2500 ° C. or lower. If the temperature is less than 2100 ° C., sufficient densification cannot be achieved and the strength may decrease. If it exceeds 2500 ° C., the thorium oxide particles and the tungsten particles may grow too much and the desired crystal structure may not be obtained. Through this step, a thorium oxide-containing tungsten alloy sintered body can be obtained. If the pre-sintered body has a cylindrical shape, the sintered body also has a cylindrical shape.
  • the processing rate of the first processing step is preferably in the range of 10% or more and 30% or less.
  • the second processing step is performed after the first processing step.
  • the second working step is preferably a rolling working with a working ratio of 40% or more and 70% or less.
  • the processing rate is [(AB) / A] ⁇ 100%.
  • a processing rate when processing a cylindrical sintered body having a diameter of 25 mm into a cylindrical sintered body having a diameter of 20 mm will be described.
  • 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. That the processing rate of the second processing step is 40% or more and 70% or less is obtained as the sectional area A, which is the sectional area of the cylindrical sintered body after the first processing step.
  • Forging is the process of hitting a sintered body with a hammer to apply pressure.
  • Rolling is a method of working while sandwiching a sintered body with two or more rollers.
  • Extrusion processing is a method of pressing strongly and extruding from a die hole.
  • the first processing step is preferably one or more of forging, rolling and extrusion. These processing methods can reduce the wire diameter W. Therefore, the pores in the cylindrical sintered body can be reduced.
  • the first processing step is preferably forging processing or extrusion processing. 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.
  • the processing rate of the first processing step is 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 processed in plural times as long as the processing rate is in the range of 10% or more and 30% or less.
  • the second processing step is 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.
  • 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, so that a difference in crystal orientation between the central portion and the surface portion is likely to occur.
  • the stress from the roller can be adjusted, so that the crystal orientation can be easily controlled.
  • the processing rate of rolling in the second processing step is 30% or more and 70% or less.
  • 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 orientation 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. It does not recrystallize when cold worked. It is important to control the crystal orientation with a structure that does not recrystallize.
  • the step of forming the tapered tip portion 3 is performed.
  • the processing of the tip portion 3 is performed 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 process.
  • the discharge lamp can be manufactured as follows. First, the cathode component 1 is connected to the electrode support rod 8. 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 8 is prepared. The cathode part 1 and the anode part 6 are arranged and fixed so as to face each other in the glass tube 9, and are sealed together with a part of the electrode support rod 8. The inside of the glass tube 9 is evacuated. During the process of manufacturing the discharge lamp, heat treatment may be performed at a temperature not lower than the recrystallization temperature of the cathode component, if necessary.
  • the first mixed raw material powder was prepared by the following method. First, ammonium tungstate (APT) powder having an average particle size of 2 ⁇ m was heated to a temperature of 500 ° C. in the atmosphere to change the ammonium tungstate powder into a tungsten oxide powder. Subsequently, thorium nitrate powder having an average particle diameter of 3 ⁇ m was added to the tungsten oxide powder, pure water was added thereto, and then the mixture was stirred for 15 hours or more to uniformly mix. Next, the water was completely evaporated to obtain a mixed powder in which the thorium nitrate powder and the tungsten oxide powder were uniformly mixed. Next, the powder was heated in the atmosphere at a temperature of 520 ° C.
  • APT ammonium tungstate
  • a first mixed raw material powder of thorium oxide powder and metallic tungsten powder was prepared.
  • the second mixed raw material powder was prepared by the following method. First, APT powder having an average particle size of 2 ⁇ m was heated to a temperature of 450 ° C. in a nitrogen atmosphere to change the ammonium tungstate powder into a tungsten oxide powder. At this time, the composition of the tungsten oxide powder obtained by mixing hydrogen in a nitrogen atmosphere was WO 2.9 . Subsequently, tungsten oxide WO 2.9 powder was reduced to metal tungsten powder was heat-treated at a temperature in a hydrogen atmosphere (reducing atmosphere) 740 ° C.. Thereby, a metal tungsten powder was prepared.
  • thorium nitrate powder and tungsten oxide WO 2.9 powder were uniformly mixed to prepare a mixed powder.
  • the powder was heated in the atmosphere at a temperature of 520 ° C. to convert the thorium nitrate powder into thorium oxide.
  • heat treatment was performed at a temperature of 800 ° C. in a hydrogen atmosphere (reducing atmosphere).
  • a second mixed raw material powder of thorium oxide powder and metallic tungsten powder was prepared.
  • a cylindrical sintered body (ingot) shown in Table 1 was formed using the first mixed raw material powder and the second mixed raw material powder.
  • the amounts of thorium in the first mixed raw material powder and the second mixed raw material powder were prepared by changing the addition amount of thorium nitrate added in producing the tungsten powder.
  • the cylindrical sintered body (ingot) was processed under the processing conditions shown in Table 2. All were processed by cold working.
  • the cylindrical sintered body obtained was cut and processed to form a tapered tip.
  • the taper angle of the tip portion was adjusted to 60 degrees or more and 80 degrees or less.
  • a cathode part for a discharge lamp was manufactured.
  • Table 3 shows the sizes of the cathode parts.
  • the crystal orientation, tungsten crystal size, and thorium crystal size were examined for the cathode parts according to the examples and comparative examples.
  • the crystal orientation was measured by performing EBSD analysis at a position within 1 mm from the center 4 of the cross section in the length T direction of the body passing through the center 4 of the body of the cathode component.
  • TFE-SEM thermal field emission scanning electron microscope
  • JSM-6500F manufactured by JEOL Ltd.
  • DigiView IV slow scan CCD camera manufactured by TSL Solution Co., Ltd.
  • OIM Data Collection ver. 7.3x OIM Analysis server. 8.0 was used.
  • the EBSD measurement conditions were an electron beam acceleration voltage of 20 kV, an irradiation current of 12 nA, and a sample inclination angle of 70 degrees.
  • the measurement area is 90 ⁇ m ⁇ 90 ⁇ m, and the measurement interval is 0.3 ⁇ m / step.
  • a cross section 5 passing through the center 4 of the body portion 2 was used as a measurement surface, and the cross section 5 was irradiated with an electron beam to obtain a diffraction pattern.
  • the grain size map of EBSD was used for the measurement of the grain size of the tungsten crystal.
  • the crystal grain map had a unit area of 90 ⁇ m ⁇ 90 ⁇ m. In the crystal grain map, those having two or more consecutive measurement points within 5 degrees of crystal orientation difference were identified as the same crystal grain. After determining the individual particle diameters, the average particle diameter D 50 and the particle diameter D 90 were determined.
  • the grain size map of EBSD was also used for the measurement of the grain size of the thorium crystal.
  • the unit area of the crystal grain map is 90 ⁇ m ⁇ 90 ⁇ m.
  • a crystal grain in which two or more measurement points within a crystal orientation difference of 2 degrees are continuously present is identified as the same crystal grain.
  • the average particle diameter D 50 and the particle diameter D 90 were determined. The results are shown in Tables 4, 5, and 6.
  • the preferential azimuth in the direction a in the cross section 5 was the ⁇ 101> azimuth.
  • the preferential azimuth in the direction a of the cross section 5 was not the ⁇ 101> azimuth.
  • the average grain size D 50 of the tungsten crystals was 20 ⁇ m or less, which satisfied D 90 ⁇ D 50 ⁇ 7 ⁇ m.
  • the thorium crystal had an average particle diameter D 50 of 3 ⁇ m or less, which satisfied D 90 ⁇ D 50 ⁇ 2 ⁇ m.
  • a discharge lamp was produced using a cathode part for a discharge lamp.
  • the flicker life of the discharge lamp was measured.
  • the durability test was performed by a lighting test.
  • the lamp voltage during lighting was 40V and the lamp voltage during non-lighting was 20V.
  • the lighting state was set to 3 hours and the non-lighting state was set to 2 hours, and this was repeated alternately.
  • Flicker was defined as 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 flicker phenomenon occurred was defined as the flicker life.
  • the average particle diameter D 50 ( ⁇ m) of the tungsten crystal was measured after 800 hours had passed.
  • the average particle diameter D 50 was measured by using the cross section of the tip portion 3 and measuring a portion having a depth of 0.5 mm from the tip portion 3. The results are shown in Table 7.
  • the flicker life of the discharge lamp according to the example was 800 hours or more, and the life was extended. This is because coarse particles are less likely to be formed in the cathode component.
  • the increase rate of the average grain size D 50 of the tungsten crystals is smaller in Examples 3 to 5 than in Examples 1 and 2. Grain growth can be suppressed by using tungsten oxide WO 2.9 once like the second mixed raw material powder.

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  • Discharge Lamp (AREA)
  • Powder Metallurgy (AREA)

Abstract

Ce composant de cathode pour une lampe à décharge comprend : une partie corps ayant un diamètre de fil de 2 à 35 mm; et une partie pointe effilée de la partie corps à l'extrémité de celle-ci. Le composant de cathode comprend un alliage de tungstène contenant de 0,5 à 3 % en masse de thorium en termes de ThO2; lorsqu'une analyse de diffraction des électrons rétrodiffusés est effectuée sur une région ayant une unité de surface de 90 µm × 90 µm et située dans 1 mm à partir du centre d'une section transversale qui passe par le centre de la partie corps et est prise le long de la direction longitudinale de la partie corps, le rapport de surface d'une phase de tungstène ayant une orientation cristalline, dont la différence d'orientation à partir de l'orientation <101> est de -15 à 15 degrés, est le plus élevé dans la cartographie de figures de pôles inverses selon une direction longitudinale.
PCT/JP2019/045311 2018-11-19 2019-11-19 Composant de cathode pour lampe à décharge, et lampe à décharge WO2020105644A1 (fr)

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JP2009259790A (ja) * 2008-03-26 2009-11-05 Harison Toshiba Lighting Corp 高圧放電ランプ
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
JP2012109192A (ja) * 2010-10-21 2012-06-07 Yumex Inc ショートアーク放電灯用陰極およびアーク放電方法
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US7262553B2 (en) * 2003-06-26 2007-08-28 Matsushita Electric Industrial Co., Ltd. High efficacy metal halide lamp with configured discharge chamber
JP5041349B2 (ja) * 2010-04-23 2012-10-03 ウシオ電機株式会社 ショートアーク型放電ランプ
JP5800922B2 (ja) * 2012-02-15 2015-10-28 株式会社東芝 放電ランプ用カソード部品

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US20060049761A1 (en) * 2004-09-07 2006-03-09 Patent-Treuhand-Gesellschaft Fur Elektrisch Gluhlampen Process for producing an electrode for high-pressure discharge lamps, and an electrode and a high-pressure discharge lamp with such electrodes
JP2009259790A (ja) * 2008-03-26 2009-11-05 Harison Toshiba Lighting Corp 高圧放電ランプ
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
JP2012109192A (ja) * 2010-10-21 2012-06-07 Yumex Inc ショートアーク放電灯用陰極およびアーク放電方法
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
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

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