WO2005091335A1 - Radiator and device comprising such radiator - Google Patents

Radiator and device comprising such radiator Download PDF

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Publication number
WO2005091335A1
WO2005091335A1 PCT/JP2005/001130 JP2005001130W WO2005091335A1 WO 2005091335 A1 WO2005091335 A1 WO 2005091335A1 JP 2005001130 W JP2005001130 W JP 2005001130W WO 2005091335 A1 WO2005091335 A1 WO 2005091335A1
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WO
WIPO (PCT)
Prior art keywords
radiator
tungsten
microcavities
carbon
electromagnetic waves
Prior art date
Application number
PCT/JP2005/001130
Other languages
French (fr)
Japanese (ja)
Inventor
Yuriko Kaneko
Makoto Horiuchi
Kazuaki Ohkubo
Mitsuhiko Kimoto
Mika Sakaue
Original Assignee
Matsushita Electric Industrial Co., Ltd.
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.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co., Ltd. filed Critical Matsushita Electric Industrial Co., Ltd.
Priority to JP2006516871A priority Critical patent/JP3825466B2/en
Priority to US11/184,258 priority patent/US20050263269A1/en
Publication of WO2005091335A1 publication Critical patent/WO2005091335A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K1/00—Details
    • H01K1/02—Incandescent bodies
    • H01K1/04—Incandescent bodies characterised by the material thereof
    • H01K1/10—Bodies of metal or carbon combined with other substance
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K1/00—Details
    • H01K1/02—Incandescent bodies
    • H01K1/04—Incandescent bodies characterised by the material thereof
    • H01K1/08—Metallic bodies
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01K—ELECTRIC INCANDESCENT LAMPS
    • H01K3/00—Apparatus or processes adapted to the manufacture, installing, removal, or maintenance of incandescent lamps or parts thereof
    • H01K3/02—Manufacture of incandescent bodies

Definitions

  • the present invention relates to a radiator having a microcavity structure that improves radiation efficiency in a specific wavelength range.
  • Incandescent lamps which are widely used as illumination light sources, have a filament that functions as a thermal radiator.
  • the thermal radiator emits electromagnetic waves by thermal radiation. It is a radiation source that emits, and thermal radiation is radiation (radiation of electromagnetic waves) generated by applying heat to atoms or molecules of an object. Thermal radiation energy is determined by the temperature of the object and has a continuous spectral distribution.
  • the heat radiator will be referred to as a “radiator”.
  • Incandescent light bulbs have excellent color rendering properties and are lit by simple equipment. However, because they use the heat generated by the filament, they emit only 10% of the visible wavelength range (the operating temperature is low). For example, 2600K). More specifically, the ratio of the energy density of infrared radiation to the total energy density of radiation is dominant, accounting for about 70%. In addition, heat loss due to gas conduction and convection in the incandescent bulb is about 20%. For this reason, the visible radiation efficiency of incandescent lamps is as low as about 151 m / W. Therefore, studies are underway to improve the efficiency of visible light radiation by suppressing infrared radiation, which accounts for about 70% of the total electromagnetic waves emitted from the radiator.
  • Patent Document 1 discloses a radiator having an array of fine waveguides (hereinafter, referred to as "cavity") formed on a surface thereof. This radiator propagates only electromagnetic radiation having a wavelength shorter than a predetermined wavelength defined by the shape and size of the cavity, and can suppress infrared radiation. According to the description of Patent Document 1, the cavity does not propagate electromagnetic radiation having a wavelength of twice or more its inner diameter.Therefore, the inner diameter of the cavity is 350 nm, and the thickness of the wall portion existing between the cavities is If the wavelength is 150 nm, photons with wavelengths longer than 700 nm will be radiated only from the wall. External electromagnetic radiation will not be propagated.
  • the total area occupied by the array of cavities is 50% of the surface area when no cavities are formed.
  • the total luminous flux at wavelengths longer than 700 nm is suppressed to about one tenth compared to tungsten at the same temperature, and at an operating temperature of 2100K, the visible radiation efficiency is about six times that of the conventional one. improves.
  • Patent Document 1 US Pat. No. 5,079,473
  • FIG. 1 is a graph showing the temperature dependence of blackbody radiation.
  • the operating temperature of the incandescent lamp is, for example, 1600 K
  • the spectral luminance distribution of light emitted from the filament is indicated by a curve marked with “1600 °” in the graph. According to this curve, the peak is at a wavelength of about 2 x m, indicating that the infrared radiation ratio is high.
  • the radiator when the temperature of the radiator rises from 1200K to 2000K, radiation in the visible region improves by more than three orders of magnitude, but radiation in the infrared region does not change much. ,. As can be seen from this, it is preferable to set the operating temperature to 2000K or higher in order to obtain visible radiation efficiently.
  • the radiator when the radiator is used as an illumination light source, if the operating temperature is lower than 2000 K, redness becomes strong, which is not preferable. For this reason, the radiator is made of a high melting point material such as tungsten that can withstand high-temperature operation at 2000K or more.
  • the inventors of the present invention formed a cavity array on the surface of tungsten and conducted various experiments. As a result, a tungsten array having a fine cavity array having an individual size of 1 ⁇ m or less was formed. An interesting phenomenon was observed in which the cavity array was destroyed in a short time at a temperature of about 1200K. As mentioned above, filaments of incandescent lamps need to operate at temperatures as high as 2000K or more, and incandescent lamps are required to have a long life. If the surface structure disappears when the structure of the cavity array is miniaturized to submicron size in order to suppress the radiation in the infrared region, such a radiator may be replaced by incandescent lamps or other light sources. It cannot be applied to devices that operate at high temperatures.
  • the present invention has been made in view of the above circumstances, and an object thereof is to provide a radiation device that operates stably at high temperatures when the cavities arranged on the surface have a microstructure of 1 ⁇ or less. Is to provide the body.
  • Another object of the present invention is to provide an incandescent lamp that includes the radiator and efficiently emits visible light.
  • Still another object of the present invention is to provide a device other than the lighting device having the above-described radiator, and a method of manufacturing the radiator.
  • the radiator of the present invention is a radiator that converts heat into an electromagnetic wave and radiates it from a surface. At least a part of the surface has a plurality of microcavities formed therein. The region has a layer containing tungsten and carbon.
  • the layer containing tungsten and carbon contains tungsten bonded to carbon.
  • the plurality of microcavities form an array in at least a part of the region.
  • each of the plurality of microcavities is formed from a recess having an inner diameter of 1 ⁇ m or less and a depth greater than the inner diameter.
  • the plurality of microcavities are periodically arranged at a pitch of 2 ⁇ m or less.
  • the plurality of microcavities are constituted by gaps between a plurality of columnar members arranged.
  • the radiator has a main body mainly made of tungsten.
  • the radiator is mainly formed of tungsten carbide.
  • an operating temperature of the radiator is 2000K or more.
  • the apparatus of the present invention provides any one of the above radiators and a container for shielding the radiators from the atmosphere. And energy supply means for supplying energy to the radiator and radiating electromagnetic waves from the radiator.
  • thermoelectric conversion device of the present invention receives any of the above radiators, a container for shielding the radiators from the atmosphere, and an electromagnetic wave radiated from the radiators, and converts them into electric energy. And a converter for supplying energy to the radiator and causing the radiator to emit electromagnetic waves.
  • a method for manufacturing a radiator according to the present invention is a method for manufacturing a radiator that converts heat into electromagnetic waves and radiates from a surface, wherein a step of preparing a tungsten member and at least a part of the surface of the tungsten member are provided. Forming a plurality of microcavities in the region, and carbonizing at least a part of the region on the surface of the tungsten member.
  • a method for manufacturing a radiator according to the present invention is a method for manufacturing a radiator that converts heat into electromagnetic waves and radiates from a surface, and prepares a member having a layer containing tungsten and carbon on at least a part of the surface. And forming a plurality of microcavities in at least a part of the surface of the member.
  • the layer containing tungsten and carbon contains tungsten bonded to carbon.
  • the step of forming the plurality of microcavities is performed by laser irradiation or sandblasting.
  • the method for producing a radiator according to the present invention is a method for producing a radiator that converts heat into electromagnetic waves and radiates from a surface, and includes a plurality of wires having a layer containing tungsten and carbon on at least a part of the surface. And forming a plurality of microcavities in gaps between the plurality of wires by bundling the plurality of wires.
  • the layer containing tungsten and carbon contains tungsten bonded to carbon.
  • the thermal stability of the microcavity structure can be improved by introducing carbon into the surface region of tungsten, so that the fine structure of the surface is broken even at high temperatures. It is possible to realize a radiator with high radiation efficiency that suppresses radiation having a wavelength longer than a predetermined wavelength. Further, according to the incandescent lamp of the present invention provided with such a radiator, a lighting fixture that efficiently converts heat energy into visible light and emits it is realized.
  • the radiation efficiency in a specific wavelength range can be increased, excellent effects can be exerted even when applied to devices other than the illumination light source.
  • FIG. 1 is a graph showing the spectral radiance of blackbody radiation.
  • FIG. 2 is a drawing showing a first embodiment of a radiator according to the present invention.
  • FIG. 3 (a) to (e) are cross-sectional views schematically showing various relationships between microcavities and tungsten compound layers.
  • FIG. 4 is a scanning electron micrograph showing the surface of tungsten after carburizing.
  • FIG. 5 is a graph showing the results of measurement by XPS (X-ray photoelectron spectroscopy).
  • FIG. 6 (a) and (b) are a surface SEM photograph before heating and a surface SEM photograph after heating, respectively, of a comparative example, and (c) and (d) respectively relate to the present embodiment.
  • FIG. 6 shows a surface SEM photograph of the radiator 1 before heating and a surface SEM photograph after heating.
  • FIG. 7 is a graph showing the concentration (partial pressure) of saturated oxygen related to the oxidation reaction of tungsten.
  • FIG. 8 is a graph showing Gibbs free energy in an oxidation reaction of a high melting point material.
  • FIG. 9 is a graph showing the emissivity of tungsten (W) and tungsten carbide (WC).
  • FIG. 10 is a drawing schematically showing the temperature and melting point at which microcavity collapses for each of tungsten and tungsten bite.
  • FIG. 11 is a drawing showing a configuration example of an incandescent lamp including the radiator 1 according to the embodiment of the present invention.
  • FIG. 12 is a view showing an electrode formed by using a carburizing process.
  • FIG. 13 is a diagram schematically showing an embodiment of a thermoelectric conversion device according to the present invention.
  • FIG. 2 is a plan view showing the surface of the radiator 1 in the present embodiment in a constitutive manner.
  • the rectangular part surrounded by the dotted line in FIG. 2 is a schematic diagram in which a partial surface of the radiator 1 is enlarged.
  • the radiator 1 of the present embodiment has a ribbon shape of 0.1 mm in width, 10 mm in length, and 0.05 mm in thickness as a whole, and is mainly formed of tungsten.
  • An array of cavities 2 having a diameter of 0.7 zm and a depth of 1.2 zm is formed on the surface of the radiator 1.
  • Each of these cavities 2 has a dimension of l ⁇ m or less in a plane parallel to the radiation surface, and is therefore referred to as “microcavity” in this specification.
  • microcavities 2 are arranged substantially periodically on the surface of radiator 1, and the distance between the center axes of two cavities that are in contact with each other in the arrangement is 1). It is set to 4 xm.
  • Such a microcavity 2 can be formed by using various fine processing techniques, but in the present embodiment, it is manufactured by irradiation with a pulse laser.
  • a method for forming a fine concave portion on the surface of an object to be processed using a pulse laser as described above is described in, for example, JP-A-2001-314989.
  • a pulse Irradiation with a laser beam with a pulse width of 100 femtoseconds having energy is used for fine processing. Irradiation of such a laser pulse is repeatedly performed several tens to several thousand times to form one microcavity 2.
  • the radiator 1 to be laser-processed is mounted on an XY stage.
  • an array of microcavities as shown in FIG. 2 can be formed.
  • the force S that periodically arranges the microcavities 2 at a substantially constant pitch the density of the microcavities 2 is made uneven, and different radiation characteristics are given according to the position of the radiator 1 You may.
  • the inner diameter and the depth of the microcavity 2 can be arbitrarily set by adjusting the irradiation energy density of the laser pulse, the beam spot diameter, the number of irradiations, and the like.
  • the most characteristic point of the radiator 1 of the present embodiment is that the radiation surface of the radiator 1 has a region (surface region) force from the surface to a depth of about 2 ⁇ m from the layer containing tungsten and carbon The point is that it is formed.
  • the layer containing tungsten and carbon at least a part of tungsten is chemically bonded to another element (such as carbon). It is referred to as a "tungsten compound layer.”
  • the surface of tungsten is carburized to form the above-mentioned tungsten compound layer.
  • Carburizing treatment is a treatment for carbonizing the surface of a metal or the like, and various methods have been developed. For example, in plasma carburization, a high-voltage DC voltage is applied between the two electrodes in a rare-gas atmosphere containing a hydrocarbon-based gas such as methane or propane containing argon and hydrogen. To generate glow discharge. Due to various electrochemical actions in the plasma generated by the glow discharge, ions such as hydrocarbon-based gases act on the surface of the workpiece to be carburized. Compared to other carburizing technologies, it has the effect of activating the surface of the workpiece and cleaning / reducing.
  • the carburizing temperature is 500-2000 ° C (eg, 1100 ° C),
  • the time is set to 4 to 48 hours (for example, 8 hours).
  • the thickness of the formed tungsten carbide conjugate layer can be controlled.
  • a tungsten compound layer with a thickness of several nm or more is considered to be sufficient.
  • the method of forming the above-mentioned tungsten compound layer is not limited to carburizing treatment, and may be performed by introducing a compound constituent element such as carbon into tungsten by carbon ion implantation or solid-phase diffusion. .
  • micro-cavity 2 arrays may be formed after carburizing tungsten. In that case, a compound layer having a thickness smaller than the depth of the microcavity 2 to be formed may be formed. This is because the array structure of the microcavities 2 is thermally stabilized even if a thin compound layer is formed only on the surface.
  • FIGS. 3A to 3E are cross-sectional views schematically showing various relationships between the microcavity 2 and the tungsten compound layer 22.
  • FIG. 3A a tungsten compound layer 22 having a thickness smaller than the depth of the microcavity is formed on the surface of the tungsten 21.
  • FIG. 3B a tungsten compound layer 22 which is thinner than that shown in FIG. 3A is formed.
  • FIG. 3 (c) shows a configuration corresponding to the case where the tungsten compound layer 22 is formed on the surface of the tank dust 22 and then the microcavity is formed.
  • the tungsten compound layer 22 does not exist on the bottom surface or side surface of the microcavity 2, but even in such a case, the structure of the microcavity is thermally stabilized.
  • the reason why the microcavity structure formed on the surface of tungsten collapses at a relatively low temperature may be due to the active migration of tungsten atoms during current heating.
  • FIG. 3D shows a structure in which the tungsten compound layer 22 is formed only on the side surface of the microcavity 2.
  • a structure for example, It is obtained by performing physical etching and thinly removing a plane parallel to the main surface. Since the tungsten compound layer 22 is also present at the edge portion 23 of the microcavity, it contributes sufficiently to the structural stability of the microcavity despite the small formation area of the compound layer as a whole. there is a possibility.
  • FIG. 3 (e) shows an example in which the entire wide area including the microcavity is composed of 22 elements of the tungsten conjugate.
  • a structure can also be obtained by using a tungsten compound such as tungsten carbide produced by sintering or the like as it is as the material of the radiator 1 instead of performing the carburizing treatment on the tungsten surface for a long time.
  • a tungsten compound such as tungsten carbide produced by sintering or the like as it is as the material of the radiator 1 instead of performing the carburizing treatment on the tungsten surface for a long time.
  • an array of microcavities is formed on the surface thereof.
  • FIG. 4 is a scanning electron microscope (SEM) photograph showing a cross section near the tungsten surface after the above-described carburizing treatment.
  • a carbon layer (C deposit) is deposited on the sample surface via a Pt-Pd layer so that the layer structure of the cross section becomes clear.
  • the layer formed by carburizing does not clearly show a polycrystalline structure like tungsten, and is composed of an amorphous phase or a microcrystalline phase. It is considered to be.
  • the thickness of the layer formed by carburizing is about 1.8 ⁇ .
  • FIG. 5 is a graph showing the results of measurement by XPS (X-ray photoelectron spectroscopy). The vertical axis of the graph indicates the photoelectrons emitted from the sample surface by irradiating the sample with X-rays in a vacuum.
  • XPS X-ray photoelectron spectroscopy
  • the 4f electron binding energy of tungsten in the layer formed by carburizing shows a chemical shift as compared with the value in the crystal of tungsten alone. I have.
  • the carbon in the carburized layer had a higher concentration than the carbon inside tungsten. From the above, at least a part of the tungsten in the carburized layer is made of another element ( Carbon) to form a compound.
  • tungsten compound layer a layer formed on the surface of tungsten by carburizing treatment. Does not mean that a layer of a compound is formed by bonding with carbon, but broadly means that at least a part of the layer containing carbon and tungsten is in a chemically bonded state.
  • radiator 1 of this embodiment providing a radiator which is not carburized on the surface (Comparative Example), in a vacuum of about 10- 6 torr, heated 10 component force opening at 2000 K.
  • FIGS. 6 (a) and 6 (b) are a surface SEM photograph before heating and a surface SEM photograph after heating, respectively, of a comparative example.
  • FIGS. 6 (c) and (d) are a surface SEM photograph before and after heating of the radiator 1 according to the present embodiment, respectively.
  • the surface of radiator 1 shown in FIGS. 6 (c) and 6 (d) is formed from the above-mentioned tungsten compound layer.
  • the microcavity structure of the radiator 1 according to the present embodiment has a force that has not changed at all after the heating test.
  • the microcavity structure collapsed. No trace was found.
  • the evaporation number flow rate of tungsten depends on the pressure of the atmospheric gas, and the higher the degree of vacuum, the easier the evaporation occurs.
  • the filament is arranged in, for example, an inert gas atmosphere of latm.
  • LATM Rere when maintained stable
  • the microcavity structure melts and disappears even at a low temperature of about 1200K.
  • the melting point of tungsten can be found in the Metal Data Book (revised). It is 3653.15K as described in the 3rd edition, edited by the Japan Institute of Metals, published by Maruzen Co., Ltd.). For this reason, at a temperature of about 1200 K, it is unlikely that the tungsten cavity structure will melt.
  • the present inventor believes that one possibility is that the fine microcavity array structure formed on the surface of tungsten is thinly oxidized, thereby greatly reducing the melting point of the surface layer. Nare, I thought.
  • FIG. 7 is a graph showing the calculation results of the saturated oxygen concentration (partial pressure) related to the tungsten oxidation reaction.
  • the vertical axis of this graph is pressure (partial pressure), and the horizontal axis is temperature.
  • the graph shows, for example, WO (s) ⁇ W02 (s) 3 ⁇ 4, the partial pressure temperature dependence of tungsten oxide in the solid state.
  • W ⁇ (g) and W ⁇ 2 (g) show the temperature dependence of the partial pressure of tantalum oxide in the gaseous state.
  • the oxidation reaction of tungsten proceeds at a low temperature of about room temperature. Therefore, even if a treatment such as hydrogen reduction is performed to remove oxygen from the tungsten surface, it is considered that the surface is easily oxidized when the tungsten surface is exposed to the atmosphere again.
  • a thin oxide layer was formed on the surface of a tungsten filament conventionally used in an incandescent light bulb when exposed to room temperature air during the manufacturing process. Such an oxide layer evaporates as soon as the bulb is turned on, but it can be inferred that the lower layer of tungsten appeared on the surface, so that it did not adversely affect the characteristics.
  • the microcavity array structure is provided on the surface as in the present invention, the situation is greatly different. That is, when the microcavity array on the tungsten surface is exposed to the air at room temperature and oxidized, the microcavity structure itself disappears when the bulb is turned on.
  • FIG. 8 is a graph showing Gibbs free energy in the oxidation reaction of a high melting point material.
  • FIG. 8 shows the oxidation resistance of each material.
  • Tantalum carbide is less likely to be oxidized than molybdenum, niobium, or tungsten. Tantalum carbide can be considered as a material having such properties in addition to tungsten carbide.
  • the tungsten compound layer formed by carburizing in the present invention also has a property of being less susceptible to oxidation than tungsten.
  • the structure of the microcavity may be thermally stabilized.
  • the compound layer in the present invention has the same properties as tungsten carbide in a Balta state.
  • the layer formed on the surface of tungsten by the carburizing treatment of the present invention indicates that tungsten is chemically bonded to other elements, and that the layer contains carbon. It is present in higher concentrations than in Tankusten. From these facts, it is clear that tungsten and carbon are chemically bonded.Since the composition ratio has not been confirmed, it cannot be concluded that this compound layer is ⁇ tungsten carbide '' .
  • tungsten carbide which is a material that is not easily oxidized, however, has not been used as a filament of an incandescent lamp.
  • the melting point of tungsten carbide is several hundred K lower than that of tungsten, and the other is the difference in the emissivity between tungsten and tungsten carbide.
  • FIG. 9 is a graph showing an example of the results of measuring the emissivity of tungsten and tungsten carbide in the infrared region.
  • the force is higher than tungsten (W).
  • Nutsten carbide (WC) emits more infrared radiation.
  • the emissivity of tungsten at a wavelength of 2.5 / im is 20%, while the emissivity of tungsten carbide at the same wavelength is 70%.
  • the proportion of visible light in the total radiation from tungsten carbide is reduced. For this reason, when a tungsten carbide power filament is produced, the luminous efficiency in the visible region is significantly lower than that of a tungsten filament, and the filament cannot be used as a light bulb at all.
  • incandescent light bulbs In the early days of the invention of incandescent light bulbs, light bulbs (Edison light bulbs) using carbon filaments having a low melting point and a high infrared emissivity were used. However, carbon filaments have since been replaced by tungsten filaments with higher melting points. From this historical background, the common sense has emerged that tungsten carbide, which has a lower melting point and higher infrared emissivity than tungsten, should not be used for radiators such as filaments.
  • the radiator of the present invention dares to use tantalum carbide having a relatively low radiation efficiency in the visible region.
  • tantalum carbide having a relatively low radiation efficiency in the visible region.
  • it since it has a fine microcavity structure on its surface, it is red. External radiation can be sufficiently suppressed, and the high infrared emissivity inherently exhibited by tungsten carbide can be suppressed to a sufficiently low level.
  • the operating temperature can be lowered as compared with the case where a tungsten filament is used.
  • FIG. 10 is a drawing schematically showing the melting point and the temperature at which the microcavity collapses for each of tungsten and tungsten carbide.
  • the melting point of tungsten carbide (WC) is about 3175K, which is lower than the melting point of tungsten (about 3650K).
  • Methodal Data Book, 3rd edition, edited by the Japan Institute of Metals, published by Maruzen ( stock ) Nevertheless, the collapse temperature of the carburized microcavity structure is around 2400K. This temperature can be predicted from the melting point of tungsten carbide, which is extremely high compared to the temperature at which the microcavity of tungsten collapses (about 1900K). It is too high value.
  • FIG. 11 is a drawing showing a configuration example of an incandescent lamp including the radiator 1 described above.
  • the incandescent lamp includes a radiator (filament) 1 that emits radiated light, a translucent bulb 12 that shields the radiator 1 from the atmosphere, and a stem 13 that supports an electrode connected to the radiator 1. And a base 14 that is electrically connected to the radiator 1 through an electrode and supplies the radiator 1 with electric power from a commercial power supply. It is preferable to fill the inside of the valve 12 with argon gas or the like to suppress the evaporation of the filament.
  • the radiator 1 since the radiator 1 has a thermally stable microcavity structure as described above, even at an operating temperature of 2000 K, a spectral distribution with little infrared radiation is obtained. The indicated radiation can be continued for a long time.
  • FIG. 12 is a diagram schematically showing a configuration example of such an electrode.
  • the tungsten electrode 30 shown in FIG. 12 has a shape in which one end of a round rod-shaped tungsten having a diameter of 0.2 to 15 m is sharpened in a conical shape, and the tip is cut by 0.2 to 0.8 mm. .
  • This tungsten electrode 30 contains thorium, and electrons are emitted from the tip.
  • the conical portion of the tungsten electrode 30 a region other than a tip from which electrons are emitted is carburized.
  • the reason for performing the carburizing treatment is to prevent thorium from diffusing through the crystal grain boundaries of the tungsten electrode and disappearing outside the electrode.
  • the carburized layer formed by the carburizing process is considered to be W2C whose melting point is lower than that of tungsten, and therefore, the relatively low temperature portion of the tungsten electrode 30 (the high temperature tip where electron emission occurs). (Except for the region).
  • a fine concave-convex structure is formed on the surface of the radiator by a method other than the method described above, and each fine concave portion (average size of concave portion: 1 ⁇ m or less)
  • the lower part may function as a microcavity.
  • by processing the surface by sandblasting it is possible to form a concave portion functioning as a microcavity on the surface of the radiator.
  • a decrease in thermal stability due to oxidation of the surface of the radiator can be suppressed, and a long-time heat radiation can be performed at a high temperature. Be able to apply.
  • the fine structure formed on the surface can be kept stable even at a high temperature of 2000 K or more.
  • a fine processing technology such as MEMS.
  • a lattice structure may be formed at intervals of about the wavelength of light by arranging and stacking fine grid members, and a photonic crystal structure may be realized on the radiation surface of the radiator.
  • the surface or the whole of the member constituting such a fine structure is formed of tungsten carbide.
  • the radiator of the present invention can also be applied to the three-dimensional tungsten structure disclosed in International Publication Pamphlet WO O3 / 058676A2.
  • members that have traditionally been improved in heat resistance using materials such as tungsten and tungsten, which have extremely high melting points, will be increasingly miniaturized in the future.
  • the present invention can solve a big problem widely.
  • thermoelectric conversion device Next, an embodiment of a thermoelectric conversion device will be described as a device other than the lighting device using the radiator according to the present invention.
  • FIG. 13 schematically shows the configuration of such a thermoelectric converter.
  • the illustrated device includes a radiator 40 of the present invention that absorbs sunlight (electromagnetic waves) and emits an electromagnetic wave of a specific wavelength, a container (not shown) that blocks the radiator 40 from atmospheric power, and a radiator. And a converter (for example, a photovoltaic cell) 44 that receives the electromagnetic wave radiated from 40 and converts it into electric energy.
  • a filter 42 for blocking an unnecessary wavelength band is optionally arranged between the radiator 40 and the converter 44.
  • the radiator 40 is a force having a main body portion mainly formed of tungsten.
  • a microstructure of a microcavity or a photonic crystal structure is formed and formed on the surface.
  • a layer containing tungsten and carbon is formed on the surface of the radiator 40 where a microstructure (such as microcavity) for enhancing the radiation efficiency in the specific wavelength range is formed as in the first embodiment. I have.
  • the radiator 40 selectively emits an electromagnetic wave of a specific wavelength due to the fine structure formed on the surface thereof, and this specific wavelength is selected as a wavelength at which the converter 44 efficiently absorbs the electromagnetic wave. .
  • radiator 40 When the radiator 40 is irradiated with a method such as condensing solar heat and energy is supplied to the radiator 40, electromagnetic waves in a specific wavelength range are radiated from the radiator 40 heated to a high temperature (for example, 2000K or more). Is done.
  • the converter 44 that receives such electromagnetic wave radiation via the filter 42 can efficiently convert it into electric energy.
  • Ordinary sunlight contains many electromagnetic waves in a wavelength range where the conversion efficiency of the converter 44 is low. However, by using the radiator 40 (and the filter 42) of the present invention, the conversion efficiency is high. Since the electromagnetic wave in the wavelength range can be supplied to the converter 44, the overall conversion efficiency in the light-heat-electricity conversion system is improved.
  • Such a thermoelectric conversion device can generate electric energy by heating the radiator 40 with energy other than light, and thus can be used for power generation devices other than the light-heat-electric conversion system.
  • thermoelectric power generation system using such a radiator having wavelength selectivity is disclosed in Japanese Patent No. 347283 and the like.
  • This patent discloses radiation using a tungsten material. Only the body is disclosed, and fine structures are destroyed by heating, and nothing is mentioned.
  • the thermal stability of the microcavity or the photonic crystal structure on the surface of the radiator 40 is increased by the layer containing S, tungsten, and carbon. Power can be maintained over a long period of time, and the radiator 40 can operate at a higher temperature. Therefore, it is possible to flexibly cope with an increase in output of a power generation system. As a result, the device of the present embodiment can greatly contribute to global environmental protection as a power generation system using sunlight.
  • the radiator of the present invention has, on its surface, a microfabricated structure for improving radiation efficiency.
  • the surface of the microfabricated structure is formed from a layer containing carbon and tungsten, it is useful as a radiator for general lighting such as a high-efficiency light bulb.
  • the incandescent lamp according to the present invention is suitably applied to a store or the like where a high-efficiency lamp is required. Furthermore, it is widely applied to devices that efficiently convert radiation in a specific wavelength range into other energy among various devices required to operate stably at high temperatures.

Abstract

Disclosed is a radiator (1) which converts heat into electromagnetic waves and emits the electromagnetic waves from the surface. A plurality of microcavities (2) are formed in at least a part of the surface of the radiator (1), and the surface of each microcavity (2) is composed of a layer containing tungsten which is bonded with carbon.

Description

明 細 書  Specification
放射体および当該放射体を備えた装置  Radiator and device equipped with the radiator
技術分野  Technical field
[0001] 本発明は、特定波長域の放射効率を向上させるマイクロキヤビティ構造を有する放 射体に関している。  The present invention relates to a radiator having a microcavity structure that improves radiation efficiency in a specific wavelength range.
背景技術  Background art
[0002] 照明光源として広く普及してレ、る白熱電球は、熱放射体 (thermal radiator)として機 能するフィラメントを有している、熱放射体は、熱放射 (thermal radiation)によって電磁 波を放出する放射源であり、熱放射は、物体の原子または分子に熱をカ卩えることによ つて生じる放射（電磁波の輻射）である。熱放射エネルギーは、物体の温度で決まり、 連続したスペクトル分布を持つ。以下、簡単のため、熱放射体を「放射体」と呼ぶこと にする。  [0002] Incandescent lamps, which are widely used as illumination light sources, have a filament that functions as a thermal radiator. The thermal radiator emits electromagnetic waves by thermal radiation. It is a radiation source that emits, and thermal radiation is radiation (radiation of electromagnetic waves) generated by applying heat to atoms or molecules of an object. Thermal radiation energy is determined by the temperature of the object and has a continuous spectral distribution. Hereinafter, for simplicity, the heat radiator will be referred to as a “radiator”.
[0003] 白熱電球は、演色性に優れ、簡単な使用器具によって点灯されるが、フィラメントの 発熱による放射を利用するため、可視波長域の放射が全体の 10%程度と少ない（動 作温度が例えば 2600Kの場合)。より具体的には、放射の全エネルギー密度に対す る赤外放射のエネルギー密度の比率が 70%程度を占め、支配的である。また、白熱 電球内の封入ガスによる熱伝導や対流による熱損失が 20%程度もある。このため、 白熱電球の可視放射効率は 151m/W程度と低い。そこで、放射体から放射される 電磁波全体の約 70%を占めている赤外放射を抑制することにより、可視光放射の効 率向上をことが検討されている。  [0003] Incandescent light bulbs have excellent color rendering properties and are lit by simple equipment. However, because they use the heat generated by the filament, they emit only 10% of the visible wavelength range (the operating temperature is low). For example, 2600K). More specifically, the ratio of the energy density of infrared radiation to the total energy density of radiation is dominant, accounting for about 70%. In addition, heat loss due to gas conduction and convection in the incandescent bulb is about 20%. For this reason, the visible radiation efficiency of incandescent lamps is as low as about 151 m / W. Therefore, studies are underway to improve the efficiency of visible light radiation by suppressing infrared radiation, which accounts for about 70% of the total electromagnetic waves emitted from the radiator.
[0004] 特許文献 1は、表面に微細な導波管（以下、「キヤビティ」と称する）のアレイを形成 した放射体を開示している。この放射体は、キヤビティの形状およびサイズによって規 定される所定の波長よりも短い波長の電磁線のみを伝播し、赤外放射を抑制すること ができる。この特許文献 1の記載によれば、キヤビティは、その内径の倍以上の波長 を有する電磁線を伝播しない、このため、キヤビティの内径が 350nm、キヤビティどう しの間に存在する壁部分の厚さが 150nmの場合、 700nmよりも長い波長のフオトン は、壁部分からのみ放射されうる力 キヤビティアレイからは、波長 700nm以上の赤 外域電磁線は伝播されないことになる。 [0004] Patent Document 1 discloses a radiator having an array of fine waveguides (hereinafter, referred to as "cavity") formed on a surface thereof. This radiator propagates only electromagnetic radiation having a wavelength shorter than a predetermined wavelength defined by the shape and size of the cavity, and can suppress infrared radiation. According to the description of Patent Document 1, the cavity does not propagate electromagnetic radiation having a wavelength of twice or more its inner diameter.Therefore, the inner diameter of the cavity is 350 nm, and the thickness of the wall portion existing between the cavities is If the wavelength is 150 nm, photons with wavelengths longer than 700 nm will be radiated only from the wall. External electromagnetic radiation will not be propagated.
[0005] 上記の設計寸法による場合、キヤビティのアレイが占める総面積は、キヤビティが形 成されない場合における表面積の 50%になる。特許文献 1によると、 700nmより長 い波長の全放射光束は、同一温度におけるタングステンに比べて約 10分の一に抑 制され、 2100Kの動作温度では、可視放射効率が従来の約 6倍に向上する。  [0005] With the above design dimensions, the total area occupied by the array of cavities is 50% of the surface area when no cavities are formed. According to Patent Document 1, the total luminous flux at wavelengths longer than 700 nm is suppressed to about one tenth compared to tungsten at the same temperature, and at an operating temperature of 2100K, the visible radiation efficiency is about six times that of the conventional one. improves.
特許文献 1：米国特許第 5,079,473号明細書  Patent Document 1: US Pat. No. 5,079,473
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0006] 熱平衡状態における熱放射のスペクトルは、プランクの放射則に従い、温度に依存 する。図 1は、黒体放射の温度依存性を示すグラフである。グラフの縦軸は、黒体の 分光放射輝度 Β λ Δ λ [単位: W' cm- 2str-l] ( Δ λ = 10nm)であり、横軸は放射 の波長 [単位： μ πι]である。 白熱電球の動作温度が例えば 1600Kの場合、そのフィ ラメントから放射される光の分光輝度分布は、グラフ中の「1600Κ」が付された曲線 で示される。この曲線によれば、ピークは波長 2 x m程度にあり、赤外の放射比率が 高いことがわかる。 [0006] The spectrum of thermal radiation in a thermal equilibrium state depends on temperature according to Planck's law of radiation. FIG. 1 is a graph showing the temperature dependence of blackbody radiation. The vertical axis of the graph is the spectral radiance of the black body Β λ Δ λ [unit: W'cm-2str-l] (Δλ = 10 nm), and the horizontal axis is the wavelength of the radiation [unit: μ πι]. . When the operating temperature of the incandescent lamp is, for example, 1600 K, the spectral luminance distribution of light emitted from the filament is indicated by a curve marked with “1600 °” in the graph. According to this curve, the peak is at a wavelength of about 2 x m, indicating that the infrared radiation ratio is high.
[0007] 図 1から明ら力、なように、放射体の温度が 1200Kから 2000Kに上昇すると、可視域 での放射が 3桁以上向上するが、赤外域での放射はあまり変化しなレ、。このこと力、ら わかるように、効率良く可視放射を得るためには、動作温度を 2000K以上に設定す ることが好ましい。特に放射体を照明光源として利用する場合は、動作温度が 2000 Kより低いと赤みが強くなり、好ましくない。このため、放射体は、 2000K以上の高温 動作に耐えられるタングステンなどの高融点材料から形成されている。  [0007] As is clear from Fig. 1, when the temperature of the radiator rises from 1200K to 2000K, radiation in the visible region improves by more than three orders of magnitude, but radiation in the infrared region does not change much. ,. As can be seen from this, it is preferable to set the operating temperature to 2000K or higher in order to obtain visible radiation efficiently. In particular, when the radiator is used as an illumination light source, if the operating temperature is lower than 2000 K, redness becomes strong, which is not preferable. For this reason, the radiator is made of a high melting point material such as tungsten that can withstand high-temperature operation at 2000K or more.
[0008] 本発明者らが、キヤビティアレイをタングステンの表面に形成し、種々の実験を行つ たところ、個々のサイズが 1 μ m以下となる微細なキヤビティのアレイが形成されたタ ングステンでは、 1200K程度の温度で短時間にキヤビティアレイが破壊するという興 味深い現象が観察された。前述のように白熱電球のフィラメントは 2000K以上の高 温で動作する必要があり、また、白熱電球の寿命は長期であることが要求される。赤 外域の放射を抑制するために、キヤビティアレイの構造をサブミクロンのサイズに微細 化した場合に、表面構造が消失するのでは、そのような放射体を白熱電球その他の 高温で動作する装置に応用することはできない。 [0008] The inventors of the present invention formed a cavity array on the surface of tungsten and conducted various experiments. As a result, a tungsten array having a fine cavity array having an individual size of 1 μm or less was formed. An interesting phenomenon was observed in which the cavity array was destroyed in a short time at a temperature of about 1200K. As mentioned above, filaments of incandescent lamps need to operate at temperatures as high as 2000K or more, and incandescent lamps are required to have a long life. If the surface structure disappears when the structure of the cavity array is miniaturized to submicron size in order to suppress the radiation in the infrared region, such a radiator may be replaced by incandescent lamps or other light sources. It cannot be applied to devices that operate at high temperatures.
[0009] 本発明は、上記事情に鑑みてなされたものであり、その目的とするところは、表面に 配列したキヤビティが 1 μ ΐη以下の微細構造を有する場合において、高温で安定に 動作する放射体を提供することにある。  The present invention has been made in view of the above circumstances, and an object thereof is to provide a radiation device that operates stably at high temperatures when the cavities arranged on the surface have a microstructure of 1 μΐη or less. Is to provide the body.
[0010] また、本発明の他の目的は、上記の放射体を備え、可視光を効率的に放射する白 熱電球を提供することにある。  [0010] Another object of the present invention is to provide an incandescent lamp that includes the radiator and efficiently emits visible light.
[0011] 本発明の更に他の目的は、上記の放射体を有する照明装置以外の装置や、放射 体の製造方法を提供することにある。  [0011] Still another object of the present invention is to provide a device other than the lighting device having the above-described radiator, and a method of manufacturing the radiator.
課題を解決するための手段  Means for solving the problem
[0012] 本発明の放射体は、熱を電磁波に変換して表面から放射する放射体であって、前 記表面の少なくとも一部の領域には複数のマイクロキヤビティが形成されており、前 記領域は、タングステンおよび炭素を含む層を有している。  [0012] The radiator of the present invention is a radiator that converts heat into an electromagnetic wave and radiates it from a surface. At least a part of the surface has a plurality of microcavities formed therein. The region has a layer containing tungsten and carbon.
[0013] 好ましい実施形態において、タングステンおよび炭素を含む前記層は、炭素と結合 したタングステンを含有してレ、る。 [0013] In a preferred embodiment, the layer containing tungsten and carbon contains tungsten bonded to carbon.
[0014] 好ましい実施形態において、前記複数のマイクロキヤビティは、前記少なくとも一部 の領域において、アレイを形成している。 [0014] In a preferred embodiment, the plurality of microcavities form an array in at least a part of the region.
[0015] 好ましい実施形態において、前記複数のマイクロキヤビティの各々は、内径が 1 μ m以下、深さが内径よりも大きい凹部から形成されてレ、る。 [0015] In a preferred embodiment, each of the plurality of microcavities is formed from a recess having an inner diameter of 1 µm or less and a depth greater than the inner diameter.
[0016] 好ましい実施形態において、前記複数のマイクロキヤビティは、 2 μ m以下のピッチ で周期的に配列されている。 In a preferred embodiment, the plurality of microcavities are periodically arranged at a pitch of 2 μm or less.
[0017] 好ましい実施形態において、前記複数のマイクロキヤビティは、配列された複数の 柱状部材の隙間から構成されている。 [0017] In a preferred embodiment, the plurality of microcavities are constituted by gaps between a plurality of columnar members arranged.
[0018] 好ましい実施形態において、前記放射体は、主としてタングステンから形成された 本体を有している。 [0018] In a preferred embodiment, the radiator has a main body mainly made of tungsten.
[0019] 好ましい実施形態において、前記放射体は、主としてタングステンカーバイドから形 成されている。  [0019] In a preferred embodiment, the radiator is mainly formed of tungsten carbide.
[0020] 好ましい実施形態において、前記放射体の動作温度は 2000K以上である。  [0020] In a preferred embodiment, an operating temperature of the radiator is 2000K or more.
[0021] 本発明の装置は、上記いずれかの放射体と、前記放射体を大気から遮断する容器 と、前記放射体にエネルギーを供給し、前記放射体から電磁波を放射させるェネル ギー供給手段とを備えている。 [0021] The apparatus of the present invention provides any one of the above radiators and a container for shielding the radiators from the atmosphere. And energy supply means for supplying energy to the radiator and radiating electromagnetic waves from the radiator.
[0022] 本発明の熱電変換装置は、上記いずれかの放射体と、前記放射体を大気から遮 断する容器と、前記放射体から放射される電磁波を受け取り、電気工ネルギ一に変 化する変換器とを備え、前記放射体にエネルギーを供給し、前記放射体から電磁波 を放射させる。  [0022] The thermoelectric conversion device of the present invention receives any of the above radiators, a container for shielding the radiators from the atmosphere, and an electromagnetic wave radiated from the radiators, and converts them into electric energy. And a converter for supplying energy to the radiator and causing the radiator to emit electromagnetic waves.
[0023] 本発明による放射体の製造方法は、熱を電磁波に変換して表面から放射する放射 体の製造方法であって、タングステン部材を用意する工程と、前記タングステン部材 の表面の少なくとも一部の領域に複数のマイクロキヤビティを形成する工程と、前記タ ングステン部材の前記表面における前記領域の少なくとも一部を炭化する工程とを 含む。  [0023] A method for manufacturing a radiator according to the present invention is a method for manufacturing a radiator that converts heat into electromagnetic waves and radiates from a surface, wherein a step of preparing a tungsten member and at least a part of the surface of the tungsten member are provided. Forming a plurality of microcavities in the region, and carbonizing at least a part of the region on the surface of the tungsten member.
[0024] 本発明による放射体の製造方法は、熱を電磁波に変換して表面から放射する放射 体の製造方法であって、タングステンおよび炭素を含む層を表面の少なくとも一部に 有する部材を用意する工程と、前記部材の表面における少なくとも一部の領域に複 数のマイクロキヤビティを形成する工程とを含む。  [0024] A method for manufacturing a radiator according to the present invention is a method for manufacturing a radiator that converts heat into electromagnetic waves and radiates from a surface, and prepares a member having a layer containing tungsten and carbon on at least a part of the surface. And forming a plurality of microcavities in at least a part of the surface of the member.
[0025] 好ましい実施形態において、タングステンおよび炭素を含む前記層は、炭素と結合 したタングステンを含有してレ、る。  [0025] In a preferred embodiment, the layer containing tungsten and carbon contains tungsten bonded to carbon.
[0026] 好ましい実施形態において、前記複数のマイクロキヤビティを形成する工程は、レ 一ザ照射またはサンドブラストによって行なう。  [0026] In a preferred embodiment, the step of forming the plurality of microcavities is performed by laser irradiation or sandblasting.
[0027] 本発明による放射体の製造方法は、熱を電磁波に変換して表面から放射する放射 体の製造方法であって、タングステンおよび炭素を含む層を表面の少なくとも一部に 有する複数の線材を用意する工程と、前記複数の線材を束ねることによって、前記 複数の線材の隙間に複数のマイクロキヤビティを形成する工程とを含む。  [0027] The method for producing a radiator according to the present invention is a method for producing a radiator that converts heat into electromagnetic waves and radiates from a surface, and includes a plurality of wires having a layer containing tungsten and carbon on at least a part of the surface. And forming a plurality of microcavities in gaps between the plurality of wires by bundling the plurality of wires.
[0028] 好ましい実施形態において、タングステンおよび炭素を含む前記層は、炭素と結合 したタングステンを含有してレ、る。  [0028] In a preferred embodiment, the layer containing tungsten and carbon contains tungsten bonded to carbon.
発明の効果  The invention's effect
[0029] 本発明によれば、タングステンの表面領域に炭素を導入することによりマイクロキヤ ビティ構造の熱的安定性を高めることができるため、表面の微細構造が高温でも壊 れず保持され、所定波長以上の波長を有する放射を抑えた高放射効率の放射体を 実現すること力 Sできる。また、このような放射体を備えた本発明の白熱電球によれば、 熱エネルギーを効率よく可視光に変化して放射する照明器具が実現する。 According to the present invention, the thermal stability of the microcavity structure can be improved by introducing carbon into the surface region of tungsten, so that the fine structure of the surface is broken even at high temperatures. It is possible to realize a radiator with high radiation efficiency that suppresses radiation having a wavelength longer than a predetermined wavelength. Further, according to the incandescent lamp of the present invention provided with such a radiator, a lighting fixture that efficiently converts heat energy into visible light and emits it is realized.
[0030] また、本発明によれば、特定の波長域における放射効率を高めることができるため 、照明光源以外の装置に適用しても優れた効果を発揮し得る。  [0030] Further, according to the present invention, since the radiation efficiency in a specific wavelength range can be increased, excellent effects can be exerted even when applied to devices other than the illumination light source.
図面の簡単な説明  Brief Description of Drawings
[0031] [図 1]黒体放射の分光放射輝度を示すグラフである。  FIG. 1 is a graph showing the spectral radiance of blackbody radiation.
[図 2]本発明による放射体の第 1の実施形態を示す図面である。  FIG. 2 is a drawing showing a first embodiment of a radiator according to the present invention.
[図 3] (a)から（e)は、マイクロキヤビティとタングステン化合物層との種々の関係を模 式的に示す断面図である。  [FIG. 3] (a) to (e) are cross-sectional views schematically showing various relationships between microcavities and tungsten compound layers.
[図 4]浸炭処理後のタングステン表面を示す走査電子顕微鏡写真である。  FIG. 4 is a scanning electron micrograph showing the surface of tungsten after carburizing.
[図 5]XPS (X線光電子分光法）による測定の結果を示すグラフである。  FIG. 5 is a graph showing the results of measurement by XPS (X-ray photoelectron spectroscopy).
[図 6] (a)および (b)は、それぞれ、比較例の加熱前における表面 SEM写真および 加熱後における表面 SEM写真であり、（c)および (d)は、それぞれ、本実施形態に 係る放射体 1の加熱前における表面 SEM写真および加熱後における表面 SEM写 真である。  [FIG. 6] (a) and (b) are a surface SEM photograph before heating and a surface SEM photograph after heating, respectively, of a comparative example, and (c) and (d) respectively relate to the present embodiment. FIG. 6 shows a surface SEM photograph of the radiator 1 before heating and a surface SEM photograph after heating.
[図 7]タングステンの酸化反応に関する飽和酸素の濃度 (分圧）を示すグラフである。  FIG. 7 is a graph showing the concentration (partial pressure) of saturated oxygen related to the oxidation reaction of tungsten.
[図 8]高融点材料の酸化反応におけるギブズ自由エネルギーを示すグラフである。  FIG. 8 is a graph showing Gibbs free energy in an oxidation reaction of a high melting point material.
[図 9]タングステン (W)およびタングステンカーバイド (WC)の放射率を示すグラフで ある。  FIG. 9 is a graph showing the emissivity of tungsten (W) and tungsten carbide (WC).
[図 10]マイクロキヤビティが崩壊する温度と融点を、タングステンおよびタングステン力 一バイトの各々について模式的に示す図面である。  FIG. 10 is a drawing schematically showing the temperature and melting point at which microcavity collapses for each of tungsten and tungsten bite.
[図 11]本発明の実施形態に係る放射体 1を備える白熱電球の構成例を示す図面で ある。  FIG. 11 is a drawing showing a configuration example of an incandescent lamp including the radiator 1 according to the embodiment of the present invention.
[図 12]浸炭処理を利用した形成された電極を示す図である。  FIG. 12 is a view showing an electrode formed by using a carburizing process.
[図 13]本発明による熱電変換装置の実施形態を模式的に示す図である。  FIG. 13 is a diagram schematically showing an embodiment of a thermoelectric conversion device according to the present invention.
符号の説明  Explanation of symbols
[0032] 1 放射体 2 キヤビティ構造 [0032] 1 radiator 2 Cavity structure
12 バルブ  12 valve
13 ステム  13 Stem
14 口金  14 base
21 タングステン  21 Tungsten
22 タングステン化合物層  22 Tungsten compound layer
30 電極  30 electrodes
40 放射体  40 radiator
42 フイノレタ  42 Huinoleta
44 変換器 (太陽電池など）  44 Converter (solar cell, etc.)
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0033] 以下、図面を参照しながら、本発明の放射体の好ましい実施形態を説明する。  Hereinafter, preferred embodiments of the radiator of the present invention will be described with reference to the drawings.
[0034] (実施形態 1)  (Embodiment 1)
まず、図 2を参照する。図 2は、本実施形態における放射体 1の表面を構成的に示 す平面図である。図 2において点線で囲まれた矩形部分は、放射体 1の一部表面を 拡大した模式図である。  First, refer to FIG. FIG. 2 is a plan view showing the surface of the radiator 1 in the present embodiment in a constitutive manner. The rectangular part surrounded by the dotted line in FIG. 2 is a schematic diagram in which a partial surface of the radiator 1 is enlarged.
[0035] 本実施形態の放射体 1は、全体として幅 0. lmm、長さ 10mm、厚さ 0. 05mmのリ ボン形状を有しており、主にタングステンから形成されている。放射体 1の表面には、 直径 0. 7 z m、深さ 1. 2 z mの円柱形状を有するキヤビティ 2のアレイが形成されて いる。これらのキヤビティ 2は、それぞれ、放射面に平行な面内において l x m以下の 寸法を有しているため、本明細書では「マイクロキヤビティ」と称することとする。  The radiator 1 of the present embodiment has a ribbon shape of 0.1 mm in width, 10 mm in length, and 0.05 mm in thickness as a whole, and is mainly formed of tungsten. An array of cavities 2 having a diameter of 0.7 zm and a depth of 1.2 zm is formed on the surface of the radiator 1. Each of these cavities 2 has a dimension of l × m or less in a plane parallel to the radiation surface, and is therefore referred to as “microcavity” in this specification.
[0036] 本実施形態では、このようなマイクロキヤビティ 2が放射体 1の表面において略周期 的に配列されており、その配列のピッチ 舞接する 2つのキヤビティの中心軸間の距 離）は 1. 4 x mに設定されている。  In the present embodiment, such microcavities 2 are arranged substantially periodically on the surface of radiator 1, and the distance between the center axes of two cavities that are in contact with each other in the arrangement is 1). It is set to 4 xm.
[0037] このようなマイクロキヤビティ 2は、種々の微細加工技術を用いて形成可能であるが 、本実施形態では、パルスレーザの照射によって作製している。このようにパルスレ 一ザを用いて被処理物の表面に微細な凹部を形成する方法は、例えば特開 2001- 314989号公報などに記載されている。本実施形態では、例えば 0. lmjのパルスェ ネルギーを有するパルス幅 100フェムト秒のレーザ光を照射して微細加工を行う。こ のようなレーザパルスの照射は、一つのマイクロキヤビティ 2を形成するために数十か ら数千回繰り返して実行される。 [0037] Such a microcavity 2 can be formed by using various fine processing techniques, but in the present embodiment, it is manufactured by irradiation with a pulse laser. A method for forming a fine concave portion on the surface of an object to be processed using a pulse laser as described above is described in, for example, JP-A-2001-314989. In the present embodiment, for example, a pulse Irradiation with a laser beam with a pulse width of 100 femtoseconds having energy is used for fine processing. Irradiation of such a laser pulse is repeatedly performed several tens to several thousand times to form one microcavity 2.
[0038] レーザ加工されるべき放射体 1は X— Yステージ上に搭載される。この X— Yステージ の動作と同期してレーザの照射を行なうことにより、図 2に示すようなマイクロキヤビテ ィのアレイを形成することができる。 X— Yステージの動作を高レ、精度で制御すること により、アレイの配列パターンを任意に設定することが可能になる。本実施形態では 、マイクロキヤビティ 2を略一定のピッチで周期的に配列している力 S、マイクロキヤビテ ィ 2の密度に粗密を設け、放射体 1の位置に応じて異なる放射特性を付与しても良い 。マイクロキヤビティ 2の内径および深さは、レーザパルスの照射エネルギー密度、ビ 一ムスポット径、照射回数などを調節することにより任意の大きさを付与できる。  [0038] The radiator 1 to be laser-processed is mounted on an XY stage. By performing laser irradiation in synchronization with the operation of the XY stage, an array of microcavities as shown in FIG. 2 can be formed. By controlling the operation of the X-Y stage with high precision and accuracy, it is possible to set the array pattern of the array arbitrarily. In the present embodiment, the force S that periodically arranges the microcavities 2 at a substantially constant pitch, the density of the microcavities 2 is made uneven, and different radiation characteristics are given according to the position of the radiator 1 You may. The inner diameter and the depth of the microcavity 2 can be arbitrarily set by adjusting the irradiation energy density of the laser pulse, the beam spot diameter, the number of irradiations, and the like.
[0039] なお、多数のマイクロキヤビティを同時に形成するためには、半導体製造分野や M EMS (Micro Electro Mechanical Systems)で広く利用されているフォトリソグラフィぉ よびエッチング技術を用いてもょレ、。  In order to simultaneously form a large number of microcavities, photolithography and etching techniques widely used in the semiconductor manufacturing field and MEMS (Micro Electro Mechanical Systems) may be used.
[0040] 本実施形態の放射体 1において最も特徴的な点は、放射体 1の放射面において表 面から深さ約 2 β mまでの領域 (表面領域）力 タングステンと炭素とを含む層から形 成されている点にある。後に詳しく説明するように、このタングステンと炭素とを含む層 では、タングステンの少なくとも一部が他の元素（炭素など）と化学的に結合している ため、本明細書においては、この層を「タングステン化合物層」と称することとする。 The most characteristic point of the radiator 1 of the present embodiment is that the radiation surface of the radiator 1 has a region (surface region) force from the surface to a depth of about 2 βm from the layer containing tungsten and carbon The point is that it is formed. As described later in detail, in the layer containing tungsten and carbon, at least a part of tungsten is chemically bonded to another element (such as carbon). It is referred to as a "tungsten compound layer."
[0041] 本実施形態では、上記のタングステン化合物層を形成するために、タングステンの 表面に対して浸炭処理を行なっている。浸炭処理は、金属などの表面を炭化する処 理であり、種々の方法が開発されている。例えば、プラズマ浸炭は、炉体 '断熱材を 陽極、被処理物を陰極とし、アルゴン '水素を含むメタンやプロパンなどの炭化水素 系ガスを含む希ガス雰囲気中で、両極間に高圧の直流電圧を印加し、グロ一放電を 発生させる。グロ一放電で生じたプラズマ中での種種の電気化学的作用により、炭化 水素系ガス等のイオンが被処理物表面に作用し、浸炭が行われる。他の浸炭技術と 比べて、被処理物表面の活性化やクリーニング ·還元といった効果がある。好ましい 実施形態において、浸炭処理温度は、 500— 2000°C (例えば 1100°C)、浸炭処理 時間は 4一 48時間（例えば 8時間）に設定される。浸炭処理の条件を調節することに より、形成されるタングステンィ匕合物層の厚さを制御することができる。熱的な安定性 を高めるには、おそらく数 nm程度以上の厚さを有するタングステン化合物層があれ ば充分であると考えられる。 In the present embodiment, the surface of tungsten is carburized to form the above-mentioned tungsten compound layer. Carburizing treatment is a treatment for carbonizing the surface of a metal or the like, and various methods have been developed. For example, in plasma carburization, a high-voltage DC voltage is applied between the two electrodes in a rare-gas atmosphere containing a hydrocarbon-based gas such as methane or propane containing argon and hydrogen. To generate glow discharge. Due to various electrochemical actions in the plasma generated by the glow discharge, ions such as hydrocarbon-based gases act on the surface of the workpiece to be carburized. Compared to other carburizing technologies, it has the effect of activating the surface of the workpiece and cleaning / reducing. In a preferred embodiment, the carburizing temperature is 500-2000 ° C (eg, 1100 ° C), The time is set to 4 to 48 hours (for example, 8 hours). By adjusting the conditions of the carburizing treatment, the thickness of the formed tungsten carbide conjugate layer can be controlled. To improve the thermal stability, a tungsten compound layer with a thickness of several nm or more is considered to be sufficient.
[0042] 上記のタングステン化合物層を形成する方法は、浸炭処理に限定されず、炭素の イオン注入や固相拡散によってタングステン中に炭素などの化合物構成元素を導入 することによって行なっても良レ、。  [0042] The method of forming the above-mentioned tungsten compound layer is not limited to carburizing treatment, and may be performed by introducing a compound constituent element such as carbon into tungsten by carbon ion implantation or solid-phase diffusion. .
[0043] 本実施形態では、タングステンの表面にマイクロキヤビティ 2のアレイを形成した後 に浸炭処理を行っているため、被処理体の表面積が大きぐタングステンを効率的に 炭化できる。ただし、タングステンに浸炭処理を行なってからマイクロキヤビティ 2のァ レイを形成しても良レ、。その場合、形成するマイクロキヤビティ 2の深さよりも小さな厚 さを有する化合物層を形成してもよい。表面部分に薄く化合物層が形成されるだけ でも、マイクロキヤビティ 2のアレイ構造は熱的に安定化されるからである。  In the present embodiment, since the carburizing treatment is performed after the microcavity 2 array is formed on the surface of tungsten, tungsten having a large surface area of the object can be efficiently carbonized. However, micro-cavity 2 arrays may be formed after carburizing tungsten. In that case, a compound layer having a thickness smaller than the depth of the microcavity 2 to be formed may be formed. This is because the array structure of the microcavities 2 is thermally stabilized even if a thin compound layer is formed only on the surface.
[0044] 図 3 (a)から（e)は、マイクロキヤビティ 2とタングステン化合物層 22との種々の関係 を模式的に示す断面図である。図 3 (a)は、マイクロキヤビティの深さに比べて厚さが 小さいタングステン化合物層 22がタングステン 21の表面に形成されている。図 3 (b) の例では、図 3 (a)に示す場合よりも更に薄いタングステン化合物層 22が形成されて レ、る。図 3 (c)は、タンクダステン 22の表面にタングステン化合物層 22を形成した後 に、マイクロキヤビティを形成した場合に相当する構成を示している。マイクロキヤビテ ィ 2の底面や側面には、タングステン化合物層 22が存在していないが、このような場 合でもマイクロキヤビティの構造は熱的に安定化される。タングステンの表面に形成し たマイクロキヤビティ構造が比較的低い温度で崩壊する原因は、通電加熱時におけ るタングステン原子のマイグレーションが活発なことに起因している可能性がある。こ のような原子のマイグレーションを抑制するには、マイクロキヤビティ構造の全表面に マイグレーションの生じにくい化合物層を形成することが好ましいが、最も構造の安 定性が損なわれやすいエッジ部のみにタングステン化合物層を形成しても良い。  FIGS. 3A to 3E are cross-sectional views schematically showing various relationships between the microcavity 2 and the tungsten compound layer 22. FIG. In FIG. 3A, a tungsten compound layer 22 having a thickness smaller than the depth of the microcavity is formed on the surface of the tungsten 21. In the example shown in FIG. 3B, a tungsten compound layer 22 which is thinner than that shown in FIG. 3A is formed. FIG. 3 (c) shows a configuration corresponding to the case where the tungsten compound layer 22 is formed on the surface of the tank dust 22 and then the microcavity is formed. The tungsten compound layer 22 does not exist on the bottom surface or side surface of the microcavity 2, but even in such a case, the structure of the microcavity is thermally stabilized. The reason why the microcavity structure formed on the surface of tungsten collapses at a relatively low temperature may be due to the active migration of tungsten atoms during current heating. In order to suppress such migration of atoms, it is preferable to form a compound layer in which migration is unlikely to occur on the entire surface of the microcavity structure.However, a tungsten compound is formed only at the edge where the stability of the structure is most likely to be impaired. A layer may be formed.
[0045] 図 3 (d)は、マイクロキヤビティ 2の側面部のみにタングステン化合物層 22が形成さ れている構造を示している。このような構造は、例えば図 3 (b)の構造の表面に対して 物理的なエッチングを行レ、、主面に平行な面を薄く除去することによって得られる。こ のタングステン化合物層 22は、マイクロキヤビティのエッジ部 23にも存在しているた め、全体として化合物層の形成面積が少ないにもかかわらず、マイクロキヤビティの 構造安定には充分に寄与する可能性がある。 FIG. 3D shows a structure in which the tungsten compound layer 22 is formed only on the side surface of the microcavity 2. Such a structure, for example, It is obtained by performing physical etching and thinly removing a plane parallel to the main surface. Since the tungsten compound layer 22 is also present at the edge portion 23 of the microcavity, it contributes sufficiently to the structural stability of the microcavity despite the small formation area of the compound layer as a whole. there is a possibility.
[0046] なお、図 3 (e)は、マイクロキヤビティを含む広い領域の全体がタングステンィ匕合物 2 2力、ら構成されている例を示している。このような構造は、浸炭処理をタングステンの 表面に対して長時間行なう代わりに、焼結などによって作製されたタングステンカー バイドなどのタングステン化合物をそのまま放射体 1の材料として用いても得られる。 この場合、適切な大きさおよび形状に加工されたタングステンカーバイド部材を用意 した後、その表面にマイクロキヤビティのアレイを形成することになる。  FIG. 3 (e) shows an example in which the entire wide area including the microcavity is composed of 22 elements of the tungsten conjugate. Such a structure can also be obtained by using a tungsten compound such as tungsten carbide produced by sintering or the like as it is as the material of the radiator 1 instead of performing the carburizing treatment on the tungsten surface for a long time. In this case, after preparing a tungsten carbide member processed into an appropriate size and shape, an array of microcavities is formed on the surface thereof.
[0047] 図 4は、前述した浸炭処理後におけるタングステン表面近傍における断面を示す走 查型電子顕微鏡（SEM)写真である。図 4では、断面の層構成が明確になるように、 試料表面に Pt— Pd層を介して炭素層（Cデポ）を堆積している。  FIG. 4 is a scanning electron microscope (SEM) photograph showing a cross section near the tungsten surface after the above-described carburizing treatment. In Fig. 4, a carbon layer (C deposit) is deposited on the sample surface via a Pt-Pd layer so that the layer structure of the cross section becomes clear.
[0048] 図 4から明ら力なように、浸炭処理によって形成された層は、タングステンのように多 結晶構造を明確に示しておらず、非晶質相または微結晶相から構成されてレ、ると考 えられる。図 4の試料では、浸炭処理によって形成された層の厚さは 1. 8 μ ΐη程度で ある。  [0048] As is clear from FIG. 4, the layer formed by carburizing does not clearly show a polycrystalline structure like tungsten, and is composed of an amorphous phase or a microcrystalline phase. It is considered to be. In the sample shown in Fig. 4, the thickness of the layer formed by carburizing is about 1.8 μΐη.
[0049] 図 5は、 XPS (X線光電子分光法）による測定の結果を示すグラフである。グラフの 縦軸は真空中に試料に X線を照射することによって試料表面から放出された光電子 FIG. 5 is a graph showing the results of measurement by XPS (X-ray photoelectron spectroscopy). The vertical axis of the graph indicates the photoelectrons emitted from the sample surface by irradiating the sample with X-rays in a vacuum.
(タングステンの 4f電子）の強度（カウント数）であり、横軸は結合エネルギー（Bindin g Energy)を示している。測定には、 Physical Electronics社製の分析装置（ESC A5400HC)を用レヽた。 X線のアノードとしては、 Monochromated— A1Kひ（14Ke v : 200W)を使用し、分析領域は直径 0. 6mmの円であった。 (4f electrons of tungsten), the intensity (count number), and the horizontal axis indicates binding energy. For measurement, an analyzer (ESC A5400HC) manufactured by Physical Electronics was used. Monochromated A1K (14 KeV: 200 W) was used as the X-ray anode, and the analysis area was a circle with a diameter of 0.6 mm.
[0050] 上記の測定結果からわかるように、浸炭処理によって形成された層（浸炭処理層） におけるタングステンの 4f電子結合エネルギーは、タングステン単体の結晶中にお ける値に比べて化学シフトを示している。また、他の測定結果から、浸炭処理層中の 炭素がタングステン内部における炭素よりも高い濃度を有していることが確認できて いる。以上のことから、浸炭処理層中のタングステンの少なくとも一部は、他の元素（ 炭素）と化学的に結合して化合物を形成していると考えられる。 [0050] As can be seen from the above measurement results, the 4f electron binding energy of tungsten in the layer formed by carburizing (carburized layer) shows a chemical shift as compared with the value in the crystal of tungsten alone. I have. In addition, other measurement results confirmed that the carbon in the carburized layer had a higher concentration than the carbon inside tungsten. From the above, at least a part of the tungsten in the carburized layer is made of another element ( Carbon) to form a compound.
[0051] 以上の測定結果に基づき、本明細書では、浸炭処理によってタングステンの表面 に形成される層を「タングステン化合物層」と称している力 このことは、その層に含ま れるタングステン原子の全てが炭素と結合して化合物の層を形成していることを意味 するものではなぐ炭素およびタングステンを含有する層の少なくとも一部が化学的 に結合した状態にあることを広く意味するものとする。  [0051] Based on the above measurement results, in this specification, a layer formed on the surface of tungsten by carburizing treatment is referred to as a "tungsten compound layer". Does not mean that a layer of a compound is formed by bonding with carbon, but broadly means that at least a part of the layer containing carbon and tungsten is in a chemically bonded state.
[0052] 本実施形態の放射体 1と、表面に浸炭処理していない放射体（比較例）を用意し、 約 10— 6torrの真空中、 2000Kで 10分力口熱した。図 6 (a)および（b)は、それぞれ、比 較例の加熱前における表面 SEM写真および加熱後における表面 SEM写真である 。図 6 (c)および (d)は、それぞれ、本実施形態に係る放射体 1の加熱前における表 面 SEM写真および加熱後における表面 SEM写真である。図 6 (c)および（d)におい て示されている放射体 1の表面は、前述したタングステン化合物層から形成されてい る。 [0052] and radiator 1 of this embodiment, providing a radiator which is not carburized on the surface (Comparative Example), in a vacuum of about 10- 6 torr, heated 10 component force opening at 2000 K. FIGS. 6 (a) and 6 (b) are a surface SEM photograph before heating and a surface SEM photograph after heating, respectively, of a comparative example. FIGS. 6 (c) and (d) are a surface SEM photograph before and after heating of the radiator 1 according to the present embodiment, respectively. The surface of radiator 1 shown in FIGS. 6 (c) and 6 (d) is formed from the above-mentioned tungsten compound layer.
[0053] 図 6からわかるように、本実施形態に係る放射体 1のマイクロキヤビティ構造は加熱 テスト後も全く変化しなかった力 比較例の放射体では、マイクロキヤビティ構造が崩 壊し、その痕跡が認められない状態に至った。  As can be seen from FIG. 6, the microcavity structure of the radiator 1 according to the present embodiment has a force that has not changed at all after the heating test. In the radiator of the comparative example, the microcavity structure collapsed. No trace was found.
[0054] タングステンの蒸発数流速は、雰囲気ガスの圧力に依存し、真空度が高くなるほど 蒸発が起こりやすくなる。実際に、本実施形態に係る放射体 1を白熱電球のフイラメン トとして用いる場合、フィラメントは例えば latmの不活性ガス雰囲気中に配置される。 このような場合の寿命を見積もるため、拡散方程式に基づいて計算すると、マイクロ キヤビティアレイが約 10— 6torrの真空中において、 2000Kで 10分間、安定に維持さ れるとレヽうことは、 latmの不活性ガス雰囲気中に置かれた場合、 2000Kで約 9700 時間、安定に維持されることに相当していることがわかる。従って、本実施形態の放 射体 1を備える白熱電球によれば、従来のタングステンフィラメントを利用した場合の 寿命 1000時間に対して、その 10倍である 10000時間程度の長寿命を期待できる。 [0054] The evaporation number flow rate of tungsten depends on the pressure of the atmospheric gas, and the higher the degree of vacuum, the easier the evaporation occurs. Actually, when the radiator 1 according to the present embodiment is used as a filament of an incandescent lamp, the filament is arranged in, for example, an inert gas atmosphere of latm. To estimate the lifetime of such cases, when calculated based on diffusion equation, in a vacuum micro Canon Activity array of about 10- 6 torr, 10 minutes at 2000 K, it intends Rere when maintained stable, LATM It can be seen that when the sample is placed in an inert gas atmosphere, it is stable for about 9700 hours at 2000K. Therefore, according to the incandescent lamp including the radiator 1 of the present embodiment, a long life of about 10,000 hours, which is ten times as long as the life of 1000 hours when a conventional tungsten filament is used, can be expected.
[0055] なお、本発明者の検討によると、比較例のようにタングステンフィラメントの表面にマ イク口キヤビティ構造を形成した場合は、 1200K程度の低温でもマイクロキヤビティ構 造が融解して消滅することがわかった。タングステンの融点は、金属データブック（改 訂 3版 ·日本金属学会編 ·発行：丸善 (株））などに記されているように 3653. 15Kで ある。このため、 1200K程度の温度では、タングステンのキヤビティ構造が融解する とは考えがたい。 According to the study of the present inventors, when a microphone opening cavity structure is formed on the surface of a tungsten filament as in a comparative example, the microcavity structure melts and disappears even at a low temperature of about 1200K. I understand. The melting point of tungsten can be found in the Metal Data Book (revised). It is 3653.15K as described in the 3rd edition, edited by the Japan Institute of Metals, published by Maruzen Co., Ltd.). For this reason, at a temperature of about 1200 K, it is unlikely that the tungsten cavity structure will melt.
[0056] 本発明者は、 1つの可能性として、タングステンの表面に形成された微細なマイクロ キヤビティのアレイ構造が薄く酸化され、それによつて表面層の融点が大きく低下して レ、るのではなレ、かと考えた。  [0056] The present inventor believes that one possibility is that the fine microcavity array structure formed on the surface of tungsten is thinly oxidized, thereby greatly reducing the melting point of the surface layer. Nare, I thought.
[0057] 図 7は、タングステンの酸化反応に関わる飽和酸素濃度 (分圧）の計算結果を示す グラフである。このグラフの縦軸は、圧力（分圧）であり、横軸は温度である。グラフに おいて、例えば、 WO (s) ^W02 (s) ¾,固体状態におけるタングステン酸化物の分 圧温度依存性を示している。また、 W〇（g)や W〇2 (g)は、気体状態におけるタンダ ステン酸化物の分圧温度依存性を示してレ、る。  FIG. 7 is a graph showing the calculation results of the saturated oxygen concentration (partial pressure) related to the tungsten oxidation reaction. The vertical axis of this graph is pressure (partial pressure), and the horizontal axis is temperature. The graph shows, for example, WO (s) ^ W02 (s) ¾, the partial pressure temperature dependence of tungsten oxide in the solid state. W〇 (g) and W〇2 (g) show the temperature dependence of the partial pressure of tantalum oxide in the gaseous state.
[0058] 図 7からわかるように、タングステンの酸化物のうち、室温程度の低い温度では微量 の酸素によってタングステンの酸化反応が進行する。従って、タングステン表面から 酸素を取り除くために水素還元などの処理を行っても、再びタングステン表面を大気 にさらすと、表面は容易に酸化すると考えられる。  As can be seen from FIG. 7, at a temperature as low as room temperature, the oxidation reaction of tungsten proceeds at a low temperature of about room temperature. Therefore, even if a treatment such as hydrogen reduction is performed to remove oxygen from the tungsten surface, it is considered that the surface is easily oxidized when the tungsten surface is exposed to the atmosphere again.
[0059] 従来、一般の白熱電球に利用されているタングステンフィラメントにおいても、製造 段階で室温の大気に晒されたときに、その表面に薄い酸化層が形成されていたと考 えられる。このような酸化層は、電球を点灯するとすぐに蒸発するが、下層のタンダス テンが表面に現れるため、特性に悪い影響を与えなかったと推察できる。  [0059] It is considered that a thin oxide layer was formed on the surface of a tungsten filament conventionally used in an incandescent light bulb when exposed to room temperature air during the manufacturing process. Such an oxide layer evaporates as soon as the bulb is turned on, but it can be inferred that the lower layer of tungsten appeared on the surface, so that it did not adversely affect the characteristics.
[0060] しかし、本発明のように、表面に微細なマイクロキヤビティアレイ構造が設けられてい ると、状況は大きく異なる。すなわち、タングステン表面のマイクロキヤビティアレイが 室温で大気に晒されて酸化した場合は、電球の点灯時にマイクロキヤビティ構造自 体が消滅してしまう。  [0060] However, when the microcavity array structure is provided on the surface as in the present invention, the situation is greatly different. That is, when the microcavity array on the tungsten surface is exposed to the air at room temperature and oxidized, the microcavity structure itself disappears when the bulb is turned on.
[0061] 図 8は、高融点材料の酸化反応におけるギブズの自由エネルギーを示すグラフで ある。図 8は、各材料の耐酸化性を表している。  FIG. 8 is a graph showing Gibbs free energy in the oxidation reaction of a high melting point material. FIG. 8 shows the oxidation resistance of each material.
[0062] 図 8に示す化学反応式から明らかなように、タングステンカーバイドが酸化タンダス テンになるには、最初にタングステンカーバイドを酸化することによってタングステン および COに分解し、次にタングステンを酸化するという 2段階の反応が連続して生じ る必要がある。また、タングステンカーバイドが酸化によってタングステンおよび COに 分解する反応は、図 8に示すようにタングステンから酸化タングステンが生成される反 応に比べて生じにくい。 [0062] As is clear from the chemical reaction formula shown in Fig. 8, in order for tungsten carbide to become tungsten oxide, a two-step process of first decomposing tungsten carbide into tungsten and CO by oxidizing tungsten carbide and then oxidizing tungsten. Reaction occurs continuously Need to be In addition, a reaction in which tungsten carbide is decomposed into tungsten and CO by oxidation is less likely to occur than a reaction in which tungsten oxide is generated from tungsten, as shown in FIG.
[0063] 以上のことから、モリブデンやニオブ、タングステンに比べ、タングステンカーバイド は酸化しにくいことがわかる。このような性質を持つ材料としては、タングステンカーバ イド以外に炭化タンタルが考えられる。  From the above, it can be seen that tungsten carbide is less likely to be oxidized than molybdenum, niobium, or tungsten. Tantalum carbide can be considered as a material having such properties in addition to tungsten carbide.
[0064] このようにタングステンカーバイドがタングステンに比べて酸化されにくいことを考慮 すると、本発明における浸炭処理によって形成されたタングステン化合物層もタンダ ステンに比較して酸化されにくい性質を持ち、そのことがマイクロキヤビティの構造を 熱的に安定化している可能性がある。  [0064] In consideration of the fact that tungsten carbide is less susceptible to oxidation than tungsten, the tungsten compound layer formed by carburizing in the present invention also has a property of being less susceptible to oxidation than tungsten. The structure of the microcavity may be thermally stabilized.
[0065] ただし、本発明における化合物層がバルタ状態にあるタングステンカーバイドと同 一の性質を有している必要はない。前述した分析結果によると、本発明の浸炭処理 によってタングステンの表面に形成された層は、タングステンが他の元素と化学的に 結合していることを示しており、しかも、その層には炭素がタンクダステン中よりも高い 濃度で存在している。これらのことから、タングステンと炭素とが化学的に結合してい ることは明らかである力 その組成比率は確認できていないため、この化合物層を「タ ングステンカーバイド」であると断定することはできない。ただし、タングステンカーバ イドと同様の性質を有していると考えられ、少なくとも部分的にはタングステンカーバ イドが形成されている可能性が高レ、。このため、上記のタングステンィ匕合物は、典型 的にはタングステンカーバイドである力 タングステンカーバイドに限定されるもので はない。  [0065] However, it is not necessary that the compound layer in the present invention has the same properties as tungsten carbide in a Balta state. According to the analysis results described above, the layer formed on the surface of tungsten by the carburizing treatment of the present invention indicates that tungsten is chemically bonded to other elements, and that the layer contains carbon. It is present in higher concentrations than in Tankusten. From these facts, it is clear that tungsten and carbon are chemically bonded.Since the composition ratio has not been confirmed, it cannot be concluded that this compound layer is `` tungsten carbide '' . However, it is considered to have the same properties as tungsten carbide, and there is a high possibility that tungsten carbide is formed at least partially. For this reason, the above-mentioned tungsten carbide ligature is not limited to tungsten carbide, which is typically tungsten carbide.
[0066] 前述したように酸化されにくい材料であるタングステンカーバイドは、しかしながら、 白熱電球のフィラメントとしては用いられてこなかった。この理由の 1つは、タンダステ ンカーバイドの融点がタングステンの融点に比べ数百 K程度も低い点にあり、更に他 の理由は、タングステンとタングステンカーバイドの間に存在する放射率の差にある。  [0066] As described above, tungsten carbide, which is a material that is not easily oxidized, however, has not been used as a filament of an incandescent lamp. One of the reasons is that the melting point of tungsten carbide is several hundred K lower than that of tungsten, and the other is the difference in the emissivity between tungsten and tungsten carbide.
[0067] 以下、図 9を参照しながら、放射率の差について説明する。  Hereinafter, the difference in emissivity will be described with reference to FIG.
[0068] 図 9は、タングステンおよびタングステンカーバイドの赤外域における放射率を測定 した結果の一例を示すグラフである。図 9からわ力、るように、タングステン (W)よりもタ ングステンカーバイド (WC)の方が赤外域での放射が強レ、。例えば波長 2. 5 /i mに おけるタングステンの放射率は 20%であるのに対して、同一波長におけるタンダステ ンカーバイドの放射率は 70%である。その結果、タングステンカーバイドからの放射 全体に占める可視域光の比率が低くなつてしまう。このため、タングステンカーバイド 力 フィラメントを作製すると、タングステンフィラメントよりも可視域における発光効率 が著しく低下し、電球としては到底利用できなくなる。 FIG. 9 is a graph showing an example of the results of measuring the emissivity of tungsten and tungsten carbide in the infrared region. As shown in Fig. 9, the force is higher than tungsten (W). Nutsten carbide (WC) emits more infrared radiation. For example, the emissivity of tungsten at a wavelength of 2.5 / im is 20%, while the emissivity of tungsten carbide at the same wavelength is 70%. As a result, the proportion of visible light in the total radiation from tungsten carbide is reduced. For this reason, when a tungsten carbide power filament is produced, the luminous efficiency in the visible region is significantly lower than that of a tungsten filament, and the filament cannot be used as a light bulb at all.
[0069] 白熱電球の開発史によれば、白熱電球が発明された初期の頃は、融点が低ぐし 力、も赤外放射率の高い炭素フィラメントを使用する電球 (エジソン電球）が使用されて いたが、その後、炭素フィラメントはより融点の高いタングステンフィラメントに置き換え られてきた。このような歴史的経緯から、タングステンよりも融点が低ぐまた赤外放射 率の高い材料であるタングステンカーバイドをフィラメントなどの放射体に使用するべ きではないとの技術常識が生まれてきた。  [0069] According to the development history of incandescent light bulbs, in the early days of the invention of incandescent light bulbs, light bulbs (Edison light bulbs) using carbon filaments having a low melting point and a high infrared emissivity were used. However, carbon filaments have since been replaced by tungsten filaments with higher melting points. From this historical background, the common sense has emerged that tungsten carbide, which has a lower melting point and higher infrared emissivity than tungsten, should not be used for radiators such as filaments.
[0070] これに対し、本発明の放射体は、可視域における放射効率が相対的に低いタンダ ステンカーバイドを敢えて用いているが、表面に微細なマイクロキヤビティ構造を具備 しているため、赤外放射を充分に抑制することができ、タングステンカーバイドが本来 的に示す高い赤外放射率を充分に低いレベルに抑制することが可能となる。  [0070] On the other hand, the radiator of the present invention dares to use tantalum carbide having a relatively low radiation efficiency in the visible region. However, since it has a fine microcavity structure on its surface, it is red. External radiation can be sufficiently suppressed, and the high infrared emissivity inherently exhibited by tungsten carbide can be suppressed to a sufficiently low level.
[0071] また、放射効率が高まるため、タングステンフィラメントを使用する場合に比べて動 作温度を低くすることもできる。  Further, since the radiation efficiency is increased, the operating temperature can be lowered as compared with the case where a tungsten filament is used.
[0072] なお、タングステンカーバイドの融点がタングステンの融点よりも格段に低いことを 考慮すると、タンクダステンの浸炭処理によってマイクロキヤビティの高温崩壊を抑制 できることは当業者に予測困難な意外な現象である。  Considering that the melting point of tungsten carbide is much lower than the melting point of tungsten, it is a surprising phenomenon that it is difficult for a person skilled in the art to predict that high-temperature collapse of microcavity can be suppressed by carburizing treatment of tank dust.
[0073] 図 10は、融点およびマイクロキヤビティが崩壊する温度を、タングステンおよびタン ダステンカーバイドの各々について模式的に示す図面である。この図からわかるよう に、タングステンの融点（約 3650K)に比べて、タングステンカーバイド（WC)の融点 は 3175K程度と低レ、 (金属データブック、改訂 3版'日本金属学会編'発行:丸善 (株 ) )。にもかかわらず、浸炭処理を行なったマイクロキヤビティ構造の崩壊する温度は、 2400K程度である。この温度は、タングステンのマイクロキヤビティが崩壊する温度（ 1900K程度）に比べて極めて高ぐタングステンカーバイドの融点からは到底予測で きない高い値である。 FIG. 10 is a drawing schematically showing the melting point and the temperature at which the microcavity collapses for each of tungsten and tungsten carbide. As can be seen from this figure, the melting point of tungsten carbide (WC) is about 3175K, which is lower than the melting point of tungsten (about 3650K). (Metal Data Book, 3rd edition, edited by the Japan Institute of Metals, published by Maruzen ( stock ) ). Nevertheless, the collapse temperature of the carburized microcavity structure is around 2400K. This temperature can be predicted from the melting point of tungsten carbide, which is extremely high compared to the temperature at which the microcavity of tungsten collapses (about 1900K). It is too high value.
[0074] 次に、図 11を参照しながら、本発明の放射体を有する照明装置の実施形態を説明 する。図 11は、上記の放射体 1を備える白熱電球の構成例を示す図面である。  Next, an embodiment of a lighting device having a radiator of the present invention will be described with reference to FIG. FIG. 11 is a drawing showing a configuration example of an incandescent lamp including the radiator 1 described above.
[0075] この白熱電球は、放射光を発する放射体 (フィラメント） 1と、放射体 1を大気から遮 蔽する透光性のバルブ 12と、放射体 1に接続された電極を支持するステム 13と、電 極を介して放射体 1に電気的に接続され、放射体 1に商用電源からの電力を供給す るための口金 14とを備えている。バルブ 12の内部には、アルゴンガスなどを封入し、 フィラメントの蒸発を抑制することが好ましレ、。  The incandescent lamp includes a radiator (filament) 1 that emits radiated light, a translucent bulb 12 that shields the radiator 1 from the atmosphere, and a stem 13 that supports an electrode connected to the radiator 1. And a base 14 that is electrically connected to the radiator 1 through an electrode and supplies the radiator 1 with electric power from a commercial power supply. It is preferable to fill the inside of the valve 12 with argon gas or the like to suppress the evaporation of the filament.
[0076] 図示される白熱電球によれば、放射体 1が前述したように熱的に安定なマイクロキヤ ビティ構造を有しているため、 2000Kの動作温度でも赤外域放射の少ない分光分 布を示す放射を長期間継続することが可能である。  According to the illustrated incandescent lamp, since the radiator 1 has a thermally stable microcavity structure as described above, even at an operating temperature of 2000 K, a spectral distribution with little infrared radiation is obtained. The indicated radiation can be continued for a long time.
[0077] なお、従来、浸炭処理によって形成した層（浸炭層）を表面の一部に設けたタンダ ステンの電極が知られてレ、る（例えば特開平 9一 111387号公報および特開平 9-11 1388号公報）。図 12は、このような電極の構成例を模式的に示す図である。図 12に 示すタングステン電極 30は、 0. 2— 15mの丸棒状タングステンの一端を円錐状に尖 らせた後、その先端部を 0. 2—0. 8mmだけカットした形状を有している。このタンダ ステン電極 30にはトリウムが含有されており、先端部からは電子が放射される。タンダ ステン電極 30における円錐状の部分のうち、電子が放射される先端部を除く領域に は浸炭処理が行われている。浸炭処理を行う理由は、トリウムがタングステン電極の 結晶粒界を拡散して電極の外部へ消失してしまうことを抑制することにある。この場合 、浸炭処理によって形成される浸炭層は、融点がタングステンよりも低い W2Cである と考えられており、したがってタングステン電極 30のうち温度の比較的低い部分（電 子放出が生じる高温の先端部を除く領域）に形成されてレ、る。  Conventionally, tungsten electrodes in which a layer (carburized layer) formed by carburizing treatment is provided on a part of the surface are known (for example, see JP-A-9-1111387 and JP-A-9-11387). 11 1388). FIG. 12 is a diagram schematically showing a configuration example of such an electrode. The tungsten electrode 30 shown in FIG. 12 has a shape in which one end of a round rod-shaped tungsten having a diameter of 0.2 to 15 m is sharpened in a conical shape, and the tip is cut by 0.2 to 0.8 mm. . This tungsten electrode 30 contains thorium, and electrons are emitted from the tip. In the conical portion of the tungsten electrode 30, a region other than a tip from which electrons are emitted is carburized. The reason for performing the carburizing treatment is to prevent thorium from diffusing through the crystal grain boundaries of the tungsten electrode and disappearing outside the electrode. In this case, the carburized layer formed by the carburizing process is considered to be W2C whose melting point is lower than that of tungsten, and therefore, the relatively low temperature portion of the tungsten electrode 30 (the high temperature tip where electron emission occurs). (Except for the region).
[0078] このように、電界/熱電子放出のためのタングステン電極の一部に浸炭処理を行な うこと自体は従来から知られているが、フィラメントのように高温での使用が必要になる 部材に浸炭処理を行なうことは報告されていない。  [0078] As described above, it is conventionally known that carburizing is performed on a part of the tungsten electrode for electric field / thermoelectron emission, but it is necessary to use a high temperature like a filament. It has not been reported to carburize parts.
[0079] なお、所定波長以上の放射を抑制するために、前述した方法以外の方法で放射体 表面に微細な凹凸構造を形成し、個々の微細な凹部（凹部の平均サイズ： 1 μ m以 下）がマイクロキヤビティとして機能するようにしてもよい。例えば、サンドブラスト処理 によって表面を加工することにより、マイクロキヤビティとして機能する凹部を放射体の 表面に形成することも可能である。そのような場合においても、本発明によれば、放 射体表面の酸化による熱的安定性低下を抑制でき、高温で長時間の熱放射が可能 となるため、白熱電球のフィラメントなどへ好適に適用できるようになる。 In order to suppress radiation of a predetermined wavelength or more, a fine concave-convex structure is formed on the surface of the radiator by a method other than the method described above, and each fine concave portion (average size of concave portion: 1 μm or less) The lower part may function as a microcavity. For example, by processing the surface by sandblasting, it is possible to form a concave portion functioning as a microcavity on the surface of the radiator. Even in such a case, according to the present invention, a decrease in thermal stability due to oxidation of the surface of the radiator can be suppressed, and a long-time heat radiation can be performed at a high temperature. Be able to apply.
[0080] このように本発明によれば、表面に形成した微細構造を 2000K以上の高温でも安 定に保つことができるが、このような効果は、放射体の表面に凹部を形成した場合に 限られず、 MEMSなどの微細加工技術を用いて、より複雑な微細構造を形成した場 合にも適用可能である。例えば、微細なグリッド状部材を配歹 積層することにより、 光の波長程度の間隔で格子構造を形成し、フォトニック結晶構造を放射体の放射面 上に実現してもよい。本発明では、このような微細構造を構成する部材の表面または 全体をタングステンカーバイドから形成する。これにより、選択された波長域の放射効 率を向上させる微細構造を高温でも長時間動作させることが可能となる。  As described above, according to the present invention, the fine structure formed on the surface can be kept stable even at a high temperature of 2000 K or more. However, such an effect is obtained when the concave portion is formed on the surface of the radiator. The present invention is not limited to this, and can be applied to a case where a more complicated fine structure is formed by using a fine processing technology such as MEMS. For example, a lattice structure may be formed at intervals of about the wavelength of light by arranging and stacking fine grid members, and a photonic crystal structure may be realized on the radiation surface of the radiator. In the present invention, the surface or the whole of the member constituting such a fine structure is formed of tungsten carbide. As a result, it becomes possible to operate the microstructure for improving the radiation efficiency in the selected wavelength range for a long time even at a high temperature.
[0081] なお、本発明の放射体は、国際公開パンフレット WO O3/058676A2に開示されて レ、る三次元的なタングステン構造にも適用化できる。すなわち、従来、タングステンと レ、う融点の極めて高い材料を用いて耐熱性の向上が図られてきた部材が今後ますま す微細化されてレ、く場合に生じえる「微細構造の崩壊」という大きな問題を、本発明 は広く解決することが可能である。  The radiator of the present invention can also be applied to the three-dimensional tungsten structure disclosed in International Publication Pamphlet WO O3 / 058676A2. In other words, members that have traditionally been improved in heat resistance using materials such as tungsten and tungsten, which have extremely high melting points, will be increasingly miniaturized in the future. The present invention can solve a big problem widely.
[0082] (実施形態 2)  (Embodiment 2)
次に、本発明による放射体を利用した照明装置以外の装置として、熱電変換装置 の実施形態を説明する。  Next, an embodiment of a thermoelectric conversion device will be described as a device other than the lighting device using the radiator according to the present invention.
[0083] 図 13は、このような熱電変換装置の構成を模式的に示している。図示されている装 置は、太陽光（電磁波）を吸収し、特定波長の電磁波を放射する本発明の放射体 40 と、この放射体 40を大気力 遮断する容器 (不図示）と、放射体 40から放射される電 磁波を受け取り、電気エネルギーに変化する変換器 (例えば光起電力電池) 44とを 備えている。図 13の例では、放射体 40と変換器 44との間に不要な波長域を遮断す るフィルタ 42がオプショナルに配置されてレ、る。  FIG. 13 schematically shows the configuration of such a thermoelectric converter. The illustrated device includes a radiator 40 of the present invention that absorbs sunlight (electromagnetic waves) and emits an electromagnetic wave of a specific wavelength, a container (not shown) that blocks the radiator 40 from atmospheric power, and a radiator. And a converter (for example, a photovoltaic cell) 44 that receives the electromagnetic wave radiated from 40 and converts it into electric energy. In the example of FIG. 13, a filter 42 for blocking an unnecessary wavelength band is optionally arranged between the radiator 40 and the converter 44.
[0084] 放射体 40は、主としてタングステンから形成された本体部分を有している力 その 表面には、マイクロキヤビティまたはフォトニック結晶構造の微細構造が形成されてレヽ る。放射体 40の表面において、上記特定波長域の放射効率を高める微細構造 (マイ クロキヤビティなど）が形成されている部分には、実施形態 1と同様にタングステンおよ び炭素を含む層が形成されている。このように放射体 40は、その表面に形成された 微細構造により、特定波長の電磁波が選択的に放射するが、この特定波長は変換器 44が効率よく電磁波を吸収する波長に選択されている。 [0084] The radiator 40 is a force having a main body portion mainly formed of tungsten. A microstructure of a microcavity or a photonic crystal structure is formed and formed on the surface. A layer containing tungsten and carbon is formed on the surface of the radiator 40 where a microstructure (such as microcavity) for enhancing the radiation efficiency in the specific wavelength range is formed as in the first embodiment. I have. As described above, the radiator 40 selectively emits an electromagnetic wave of a specific wavelength due to the fine structure formed on the surface thereof, and this specific wavelength is selected as a wavelength at which the converter 44 efficiently absorbs the electromagnetic wave. .
[0085] 太陽熱を集光するなどの方法によって放射体 40を照射して放射体 40にエネルギ 一を供給すると、高温 (例えば 2000K以上）に加熱された放射体 40から特定波長域 の電磁波が放射される。このような電磁波の放射を、フィルタ 42を介して受けとつた 変換器 44は、効率よく電気エネルギーに変換することができる。  When the radiator 40 is irradiated with a method such as condensing solar heat and energy is supplied to the radiator 40, electromagnetic waves in a specific wavelength range are radiated from the radiator 40 heated to a high temperature (for example, 2000K or more). Is done. The converter 44 that receives such electromagnetic wave radiation via the filter 42 can efficiently convert it into electric energy.
[0086] 通常の太陽光には、変換器 44による変換効率の低い波長域の電磁波が多く含ま れているが、本発明の放射体 40 (およびフィルタ 42)を用いることにより、変換効率の 高い波長域の電磁波を変換器 44に供給できるため、光一熱一電気変換システムにお ける全体の変換効率が高められる。このような熱電変換装置は、光以外のエネルギ 一によつて放射体 40を加熱することによつても電気エネルギーを生成できるため、光 -熱 -電気変換システム以外の発電装置に利用できる。  [0086] Ordinary sunlight contains many electromagnetic waves in a wavelength range where the conversion efficiency of the converter 44 is low. However, by using the radiator 40 (and the filter 42) of the present invention, the conversion efficiency is high. Since the electromagnetic wave in the wavelength range can be supplied to the converter 44, the overall conversion efficiency in the light-heat-electricity conversion system is improved. Such a thermoelectric conversion device can generate electric energy by heating the radiator 40 with energy other than light, and thus can be used for power generation devices other than the light-heat-electric conversion system.
[0087] なお、このような波長選択性を有する放射体を用いる熱起電力発電システムは、特 許第 347283号明細書などに開示されている力 この特許明細書にはタングステン 材料を用いた放射体しか開示されておらず、微細な構造が加熱によって崩壊するこ とにっレ、ては何も言及されてレ、なレ、。  [0087] A thermoelectric power generation system using such a radiator having wavelength selectivity is disclosed in Japanese Patent No. 347283 and the like. This patent discloses radiation using a tungsten material. Only the body is disclosed, and fine structures are destroyed by heating, and nothing is mentioned.
[0088] 本実施形態によれば、放射体 40の表面のマイクロキヤビティまたはフォトニック結晶 構造の熱的安定性力 S、タングステンおよび炭素を含む層によって高められているた め、発電システムの信頼性を長時間にわたって高く維持することができるとともに、放 射体 40のより高温での動作が可能になるため、発電システムの高出力化にもフレキ シブルに対応できる。この結果、本実施形態の装置は、太陽光を利用する発電シス テムとして地球環境保護に大いに貢献することができる。  According to the present embodiment, the thermal stability of the microcavity or the photonic crystal structure on the surface of the radiator 40 is increased by the layer containing S, tungsten, and carbon. Power can be maintained over a long period of time, and the radiator 40 can operate at a higher temperature. Therefore, it is possible to flexibly cope with an increase in output of a power generation system. As a result, the device of the present embodiment can greatly contribute to global environmental protection as a power generation system using sunlight.
産業上の利用可能性  Industrial applicability
[0089] 本発明の放射体は、その表面に放射効率を向上させる微細加工構造物を有し、か つ、その微細加工構造物の表面が炭素およびタングステンを含有する層から形成さ れているため、高効率電球などの一般照明用の放射体として有用である。また、本発 明による白熱電球は、高効率ランプが要求される店舗用などに好適に応用される。 更に、高温で安定に動作することが求められる各種の装置のうち、特定波長域の放 射を効率的に他のエネルギーに変換する装置に広く適用される。 [0089] The radiator of the present invention has, on its surface, a microfabricated structure for improving radiation efficiency. On the other hand, since the surface of the microfabricated structure is formed from a layer containing carbon and tungsten, it is useful as a radiator for general lighting such as a high-efficiency light bulb. Further, the incandescent lamp according to the present invention is suitably applied to a store or the like where a high-efficiency lamp is required. Furthermore, it is widely applied to devices that efficiently convert radiation in a specific wavelength range into other energy among various devices required to operate stably at high temperatures.

Claims

請求の範囲 The scope of the claims
[I] 熱を電磁波に変換して表面から放射する放射体であって、  [I] A radiator that converts heat into electromagnetic waves and radiates from the surface,
前記表面の少なくとも一部の領域には複数のマイクロキヤビティが形成されており、 前記領域は、タングステンおよび炭素を含む層を有している、放射体。  A radiator, wherein a plurality of microcavities are formed in at least a part of an area of the surface, and the area has a layer containing tungsten and carbon.
[2] タングステンおよび炭素を含む前記層は、炭素と結合したタングステンを含有して レ、る請求項 1に記載の放射体。  [2] The radiator according to claim 1, wherein the layer containing tungsten and carbon contains tungsten bonded to carbon.
[3] 前記複数のマイクロキヤビティは、前記少なくとも一部の領域において、アレイを形 成している請求項 1に記載の放射体。 3. The radiator according to claim 1, wherein the plurality of microcavities form an array in the at least a part of the region.
[4] 前記複数のマイクロキヤビティの各々は、内径が 1 μ m以下、深さが内径よりも大き い凹部から形成されている請求項 1に記載の放射体。 4. The radiator according to claim 1, wherein each of the plurality of microcavities is formed of a concave portion having an inner diameter of 1 μm or less and a depth greater than the inner diameter.
[5] 前記複数のマイクロキヤビティは、 2 μ ΐη以下のピッチで周期的に配列されている請 求項 1に記載の放射体。 5. The radiator according to claim 1, wherein the plurality of microcavities are periodically arranged at a pitch of 2 μΐη or less.
[6] 前記複数のマイクロキヤビティは、配列された複数の柱状部材の隙間から構成され ている請求項 1に記載の放射体。 6. The radiator according to claim 1, wherein the plurality of microcavities are constituted by gaps between a plurality of columnar members arranged.
[7] 前記放射体は、主としてタングステンから形成された本体を有している請求項 1に 記載の放射体。 [7] The radiator according to claim 1, wherein the radiator has a main body mainly made of tungsten.
[8] 前記放射体は、主としてタングステンカーバイドから形成されている請求項 1に記載 の放射体。  [8] The radiator according to claim 1, wherein the radiator is mainly formed of tungsten carbide.
[9] 前記放射体の動作温度は 2000K以上である請求項 1から 8のいずれかに記載の 放射体。  [9] The radiator according to any one of claims 1 to 8, wherein an operating temperature of the radiator is 2000K or more.
[10] 請求項 1から 9のいずれかに記載の放射体と、  [10] The radiator according to any one of claims 1 to 9, and
前記放射体を大気から遮断する容器と、  A container for shielding the radiator from the atmosphere;
前記放射体にエネルギーを供給し、前記放射体から電磁波を放射させるエネルギ 一供給手段と、  Energy supplying means for supplying energy to the radiator and radiating electromagnetic waves from the radiator;
を備えた装置。  An apparatus equipped with.
[II] 請求項 1から 9のいずれかに記載の放射体と、  [II] The radiator according to any one of claims 1 to 9, and
前記放射体を大気から遮断する容器と、  A container for shielding the radiator from the atmosphere;
前記放射体から放射される電磁波を受け取り、電気エネルギーに変化する変換器 と、 A converter that receives electromagnetic waves radiated from the radiator and converts it into electrical energy When,
を備え、  With
前記放射体にエネルギーを供給し、前記放射体から電磁波を放射させる熱電変換 装置。  A thermoelectric conversion device that supplies energy to the radiator and emits electromagnetic waves from the radiator.
[12] 熱を電磁波に変換して表面から放射する放射体の製造方法であって、  [12] A method for producing a radiator that converts heat into electromagnetic waves and radiates from a surface,
タングステン部材を用意する工程と、  Preparing a tungsten member;
前記タングステン部材の表面の少なくとも一部の領域に複数のマイクロキヤビティを 形成する工程と、  Forming a plurality of microcavities in at least a part of the surface of the tungsten member;
前記タングステン部材の前記表面における前記領域の少なくとも一部を炭化する 工程と、  Carbonizing at least a part of the region on the surface of the tungsten member;
を含む放射体の製造方法。  A method for producing a radiator comprising:
[13] 熱を電磁波に変換して表面から放射する放射体の製造方法であって、 [13] A method for producing a radiator that converts heat into electromagnetic waves and radiates from a surface,
タングステンおよび炭素を含む層を表面の少なくとも一部に有する部材を用意する 工程と、  Providing a member having a layer containing tungsten and carbon on at least a portion of the surface;
前記部材の表面における少なくとも一部の領域に複数のマイクロキヤビティを形成 する工程と、  Forming a plurality of microcavities in at least a partial region of the surface of the member;
を含む放射体の製造方法。  A method for producing a radiator comprising:
[14] タングステンおよび炭素を含む前記層は、炭素と結合したタングステンを含有して レ、る請求項 13に記載の放射体の製造方法。 14. The method for manufacturing a radiator according to claim 13, wherein the layer containing tungsten and carbon contains tungsten bonded to carbon.
[15] 前記複数のマイクロキヤビティを形成する工程は、レーザ照射またはサンドブラスト によつて行なう請求項 12または 13に記載の製造方法。 15. The method according to claim 12, wherein the step of forming the plurality of microcavities is performed by laser irradiation or sandblasting.
[16] 熱を電磁波に変換して表面から放射する放射体の製造方法であって、 [16] A method for producing a radiator that converts heat into electromagnetic waves and radiates from a surface,
タングステンおよび炭素を含む層を表面の少なくとも一部に有する複数の線材を用 意する工程と、  Providing a plurality of wires having a layer containing tungsten and carbon on at least a portion of the surface;
前記複数の線材を束ねることによって、前記複数の線材の隙間に複数のマイクロキ ャビティを形成する工程と、  Forming a plurality of microcavities in gaps between the plurality of wires by bundling the plurality of wires;
を含む放射体の製造方法。  A method for producing a radiator comprising:
[17] タングステンおよび炭素を含む前記層は、炭素と結合したタングステンを含有して レ、る請求項 16に記載の放射体の製造方法。 [17] The layer containing tungsten and carbon contains tungsten bonded to carbon. 17. A method for producing a radiator according to claim 16.
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