JP2005206936A - Metal sheet in which carbon nanofiber is easy to be formed, its production method, and nanocarbon emitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel sheet in which the formation of carbon nanofibers is easy to be controlled and can be uniformized, and an electron emission device of high performance can inexpensively be produced, to provide its production method, and to provide a nanocarbon emitter. <P>SOLUTION: Regarding the metal sheet in which carbon nanofibers are easy to be formed, in the metal sheet made of steel comprising C at a mean concentration of ≤1 mass% in the sheet thickness direction, many microregions where the metal sheet face is exposed are formed on the surface of the metal sheet, and further, each film layer on which carbon nanofibers are hard to be formed is formed on the surface of the metal sheet other than the microregions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal plate that can easily form a carbon nanofiber as a substrate material for manufacturing an electron-emitting device composed of needle-like emitter electrodes, a method for manufacturing the same, and a carbon nanofiber formed on the substrate material. The present invention relates to a nanocarbon emitter as an electron-emitting device having a needle-like emitter electrode.

  As one type of flat panel display, FED (Field Emission Display) has been actively researched. In this FED, a cathode substrate and an anode substrate are opposed to each other, and a large number of needle-shaped electron-emitting devices are arranged on the cathode substrate, and electrons are emitted toward the anode substrate to cause the phosphor layer on the anode substrate to emit light. .

  Generally, the electron-emitting device formed on the cathode substrate has a needle-like protruding electrode suitable for electron emission. For example, an electron-emitting device using an electrode made of a conical metal with a sharp tip is widely used.

  Patent Document 1 proposes an electron-emitting device, a focusing electrode for the electron-emitting device, and a manufacturing method thereof. The purpose of this is to improve the electron convergence on the counter substrate side of the electron-emitting device. A metal plate with a fine opening corresponding to the emitter electrode is provided in parallel, and a negative voltage is applied to this to converge. By using the electrode, the electron beam emitted from the emitter tip on the cathode side can be efficiently converged.

As a method for manufacturing the emitter-side electron-emitting device, the surface of the silicon substrate on the emitter electrode side is thermally oxidized, a thermal oxide film made of SiO ₂ is formed on the surface, and an inorganic resist film and further an organic resist are formed thereon. Layers are sequentially stacked. After the organic resist layer is formed in a predetermined pattern, the inorganic resist layer is etched and used as a mask, and the thermal oxide film made of SiO ₂ is etched by reactive ion etching or the like to remove the organic resist). Subsequently, when the silicon substrate is isotropically etched with an aqueous potassium hydroxide solution using an inorganic resist as a mask, the shape of a needle-shaped tip appears.

  Patent Document 2 proposes a surface conduction electron-emitting device, a focusing electrode for the electron-emitting device, and a manufacturing method thereof. The purpose of this is to increase the convergence of the electron beam, as in Patent Document 1, except that a surface conduction electron-emitting device is used, and a negative voltage is applied to the metal plate in which the opening is formed. Efficiently focuses the beam inside the aperture. In particular, since the converging electrode is formed on one common metal plate, it can be integrated with the anode side substrate or the cathode side substrate, and variation among elements can be eliminated.

Utilizing carbon nanofibers or carbon fine fibers as an electron-emitting device has also been studied for these electrode forming methods. For example, Non-Patent Document 1 proposes a method of manufacturing an emitter electrode for FED by a thermal CVD method. According to this method, using a mixed gas of CO and H ₂ as a raw material gas, the cathode substrate for FED disposed in the chamber is heated with an infrared lamp installed outside the chamber. A catalytic metal film is formed on the substrate, and CO molecules are separated by the catalyst to generate carbon nanofibers or carbon fine fibers.

  Patent Document 3 also proposes a method for producing carbon nanofibers or carbon fine fibers. In this method, catalyst particles are arranged on a cathode electrode on a substrate by a gas deposition method, and a fiber mainly composed of carbon is grown from the gas phase using the catalyst particles as nuclei.

Patent Document 4 proposes a field emission device that reduces the power consumption by increasing the aspect ratio of the emitter, thereby reducing the power consumption and a method for manufacturing the same. In this semiconductor device manufacturing process, a nanometer-sized hole is first formed in a silicon substrate, and an emitter is formed in the hole to increase the emitter aspect ratio.
JP-A-9-274845 Japanese Patent Laid-Open No. 9-283013 JP 2003-160321 A JP 2003-203556 A Hirohiko Murakami, “Development of nanocarbon materials for FED”, Metals, Agne Technology Center, September 2002, vol.72, No.9, p872-875

  However, in order to produce an image display device using a field emission type cathode, it is required to increase the amount of electrons emitted from the emitter in order to obtain a high brightness like a CRT. For this purpose, a structure in which the tip of the emitter is sharpened must be provided so that the electric field concentration on the emitter tip tends to occur.

  In the techniques described in Patent Documents 1 and 2, the tip of the emitter is sharpened by etching, but the control of etching is not always easy, and a tip having a sufficiently small radius of curvature cannot be obtained stably. Furthermore, when etching a large number of emitters at the same time, it is difficult to align the shape of the tip of each emitter. If the tip of the emitter tip is not sufficiently sharpened, there is a problem that the electric field strength is lowered, the emission current is lowered, and sufficient luminance cannot be obtained.

  In that respect, since carbon nanofibers have a high aspect ratio, the electric field tends to concentrate on the tip, and electrons can be emitted at a low voltage. Furthermore, since the individual dimensions (outer diameter) are fine, it is possible to arrange and arrange them at a high density per unit area.

  However, as in the technique described in Non-Patent Document 1, in the method of forming a catalyst metal film, defects (nonuniform distribution density of carbon nanofibers) due to nonuniform film formation cannot be avoided. Alternatively, in the technique described in Patent Document 3, it is necessary to dispose the catalyst particles on the substrate, and it is inevitable that the distribution density of the carbon nanofibers is uneven due to the uneven distribution density of the catalyst particles.

  The present invention solves these problems, makes it easy to control the generation of carbon nanofibers, makes it uniform, and makes it possible to produce an electron-emitting device at low cost and with high performance. It is an object to provide a manufacturing method and a nanocarbon emitter.

  The above problems are solved by the following invention. The invention is as follows.

  In the invention, a metal plate made of steel containing C in an average concentration in the thickness direction of 1 mass% or less C, the surface of the metal plate is formed with a number of microregions where the metal plate surface is exposed, It is a metal plate that is easy to form carbon nanofibers, characterized in that a coating layer that is difficult to form carbon nanofibers is formed on the surface of the metal plate other than the minute region.

  The carbon nanofiber in the present invention is different from the carbon nanotube in the arrangement structure of the atomic plane. FIG. 8 shows the difference depending on the form of various carbon fibers. Carbon nanotubes (in the figure, single-walled and multi-walled carbon nanotubes) have an outer atomic plane parallel to the fiber growth direction, whereas carbon nanofibers have an outer atomic plane relative to the fiber growth direction. Are not parallel. As described above, this carbon nanofiber has a more preferable structure as an electron emission source because the crystal planes are not parallel and there are many crystal defects on the fiber surface as compared with the carbon nanotube.

  In the present invention, the coating layer that is difficult to form the carbon nanofibers may be a coating layer that has an insulating property and is difficult to form the carbon nanofibers. In each of the inventions, a concave hole may be formed on the surface of the metal plate in the minute region. Moreover, in each said invention, the decarburization layer can be formed in the metal plate surface layer and its vicinity.

  The invention of the production method capable of producing the metal plate of the above invention is to hot-roll a metal plate made of steel containing 1 mass% or less of C in an average concentration in the plate thickness direction, and then perform cold rolling once. As described above, when the annealing is performed once or more as necessary to obtain a predetermined plate thickness, decarburization annealing is performed as necessary during or after any step after hot rolling, and the obtained metal plate A coating layer on which carbon nanofibers are difficult to form is formed on the surface, and then a number of micropores that penetrate the coating layer on which carbon nanofibers are difficult to form and reach the surface of the metal plate or the surface layer are formed. A method for producing a metal plate that is easy to form carbon nanofibers is characterized by forming a large number of minute regions that do not have a coating layer that is difficult to form carbon nanofibers.

  Moreover, in the said invention, the process of forming the said carbon nanofiber can also form the film layer which cannot form a carbon nanofiber easily after forming an insulating layer.

  In the present invention, the coating layer that is difficult to form the carbon nanofibers may be a coating layer that has insulating properties and is difficult to form the carbon nanofibers.

  In each of the manufacturing methods described above, the coating layer that hardly forms carbon nanofibers is penetrated (when the coating layer that is difficult to form carbon nanofibers is formed after forming the insulating layer, both layers are penetrated. The method of forming a large number of micro holes reaching the surface or the surface layer of the metal plate to form a large number of micro regions where the metal plate surface is exposed is not particularly limited.

  The step of forming a large number of minute regions where the metal plate surface is exposed may be a photoetching step. In addition, after masking the sacrificial layer by photofabrication technology or the like on the surface of the obtained metal plate, after forming a coating layer that is difficult to form carbon nanofibers or a coating layer that is difficult to form an insulating layer and carbon nanofibers Alternatively, a large number of through holes (micropores) may be formed in the coating layer in which the sacrificial layer is peeled off and the carbon nanofibers are not easily formed, or in the coating layer in which the insulating layer and the carbon nanofibers are not easily formed. When the above-mentioned through-holes are formed by photoetching, the coating layer and the insulating layer can be drilled simultaneously, so that the process can be omitted.

  The nanocarbon emitter of the present invention uses a metal plate that is easy to form the carbon nanofibers of the above inventions, or a metal plate that is easy to form the carbon nanofibers manufactured by the methods of the above inventions. It is a nanocarbon emitter excellent in discharge characteristics, characterized in that carbon nanofibers are formed on the surface of a metal plate in a minute hole portion by a CVD method or a plasma arc method.

  By applying the metal plate that is the subject of the present invention to the nanocarbon emitter, the conventionally used glass substrate becomes unnecessary, so the emitter structure itself can be simplified and the cost of the FED panel can be reduced. Can contribute. Further, by using the metal plate characterized in the present invention, the carbon nanofibers produced on the metal substrate become more uniform than those produced on the catalytic metal deposited on the glass substrate. Also, the electron emission characteristics are improved, and an excellent effect is exhibited.

  In these inventions, when a metal plate containing the above-described element is subjected to a thermal CVD method, a plasma arc method, or a plasma CVD method, precipitation of C is observed on the metal plate in the through-hole portion. Preferably, it was made based on the knowledge that precipitation of C is preferentially seen in a region where the C concentration in steel is high due to the formation of a decarburized layer. That is, there is no coating layer that is difficult to form carbon nanofibers on the surface of the metal plate, or a coating layer that is difficult to form an insulating layer and carbon nanofibers, and a large number of minute regions with exposed metal plate surfaces are formed, or By forming a concave hole on the surface of the metal plate in the minute region, C deposition is preferentially performed in the minute region by a thermal CVD method, a plasma arc method or a plasma CVD method, and in the minute region. When a recess is formed, carbon nanofibers are generated in a region with a high C concentration by preferentially precipitating C in the recess, more preferably by giving a predetermined distribution to the C concentration of the metal plate. Utilizes easy things.

  In the steel of the present invention, C is an essential element for efficiently forming carbon nanofibers. However, if the C content exceeds 1 mass% in the average concentration in the plate thickness direction, the cold workability deteriorates and the yield in manufacturing the steel sheet is remarkably reduced. Therefore, the upper limit of the C content is set to 1 mass%. On the other hand, when the amount of C is small, the formation of carbon nanofibers is inefficient, but fine carbon nanofibers with a high aspect ratio can be obtained. In this case, from the viewpoint of C amount adjustment cost, the lower limit of the C amount is preferably 0.0001 mass% (hereinafter simply referred to as “%”).

  Carbon steel and extremely low carbon are suitable for the steel to be used in the present invention. Here, the ultra-low carbon steel also contains pure iron having a purity higher than that obtained industrially. Specifically, C: 0.005% or less, Si: 0.05% or less, Mn: 0.5% or less, P: 0.05% or less, N: 0.005% or less, S: 0.01% or less, sol.Al: 0.0001 to 0.1% A range is preferable. At this time, in order to make the generation of carbon nanofibers uniform, it is important to control C, Si, Mn, P, N, S to the specified value or less, and furthermore, control of sol. This is important for miniaturizing non-metallic inclusions and reducing the total amount to a level necessary to uniformly produce the carbon nanofibers featured in the present application.

  Carbon steel is C: 1% or less, Si: 0.5% or less (except for C: 0.005% or less and Si: 0.05% or less), Mn: 1% or less, P: 0.05% or less, N 0.005% or less, S; 0.01% or less, sol.Al; preferably in the range of 0.0001 to 0.1%. At this time, in order to make the generation of carbon nanofibers uniform, it is important to control C, Si, Mn, P, N, S to the specified value or less, and furthermore, control of sol. This is important for miniaturizing non-metallic inclusions and reducing the total amount to a level necessary to uniformly produce the carbon nanofibers featured in the present application.

  Moreover, when using the above-mentioned ultra low carbon steel, since the fiber of the carbon nanofiber to produce | generate refines | miniaturizes, it is preferable.

  In the present invention, as a more preferable form, a decarburized layer is formed on the surface portion of the metal plate made of steel, and a concentration gradient is given in the thickness direction of the metal plate. If a part of this surface layer part is removed by etching or the like to provide a recess, the C concentration increases in the thickness direction of the metal plate, so that the C concentration on the bottom surface of the recess becomes the highest. As a result, the metal plate having the recesses and the coating layer formed on the surface is treated with a plasma arc method or a plasma CVD method, so that carbon having excellent discharge characteristics is formed on the bottom surface of the recesses and in the vicinity thereof. Nanofibers can be preferentially generated.

  For example, in the image display device, the size of the minute region formed on the surface of the metal plate is one pixel size or less. The above-described minute region of the metal plate and the hole formed in the minute region can be formed by photoetching or the like in accordance with the shape, size, and distribution of each target FED phosphor. Further, in the present invention, by disposing a Cu or Al layer on the metal plate, the thermal conductivity and heat dissipation of the metal substrate that becomes the cathode electrode when FED is formed can be improved.

  According to the present invention, by forming a large number of minute regions for forming carbon nanofibers as a metal plate made of steel, which is easy to form carbon nanofibers, the conditions for generating carbon nanofibers are almost the same for all the minute regions. Become. According to the present invention, on the surface of the metal plate, there is no coating layer that is difficult to form carbon nanofibers, or a micro region that does not have a coating layer that is difficult to form an insulating layer and carbon nanofibers is formed, or in the micro region. By forming the concave hole, the carbon nanofiber can be effectively formed only in the minute region portion or the hole portion. Therefore, it is possible to essentially avoid non-uniformity of the carbon nanofiber generation conditions such as non-uniformity of the catalyst metal film formation, which is essential in the prior art. As a result, it becomes easy to manufacture a highly reliable nanocarbon emitter with few defects. Further, by causing the bottom surface of the recess to reach a region having a high C concentration, the conditions for generating the carbon nanofibers are substantially the same for all the recesses.

  In carrying out the invention, the steel components are adjusted so that the C content is 1 mass% or less in terms of the average concentration in the thickness direction. About other elements, even if it contains about a normal thin steel plate, there is no particular problem in the production of carbon nanofibers. Rather, from the viewpoint of etching properties, the C content is preferably 0.5% or less.

  Steel is hot-rolled, cold-rolled, and annealed as needed one or more times to produce a metal plate made of steel with a predetermined thickness. In that case, more preferably, a decarburization annealing is performed in the process in the meantime or a final process, and a decarburization layer is formed in the metal plate surface layer part, and the more preferable metal plate which this invention intends can be obtained. In addition, decarburization annealing may be performed under the decarburization annealing conditions in a normal thin steel plate, but in order to ensure a concentration gradient in the thickness direction of the metal plate, the decarburization time should be 60 seconds to 3 hours. Is desirable.

The coating layer that is difficult to form the carbon nanofibers to be formed on the surface of the metal plate is desirably a coating that is corroded and removed during photoetching of the concave portion of the metal plate and that C is not easily precipitated. For example, a film of indium oxide (In ₂ O ₃ ), ITO (Indium Tin Oxide: In ₂ O ₃ —SnO ₂ ), which is a transparent conductive film, or Cr or a Cr-based alloy may be formed. Insulating coatings that are hard to form carbon nanofibers include indium oxide (In ₂ O ₃ ) and ITO (Indium Tin Oxide: In ₂ O ₃ -SnO ₂ ), which is a transparent conductive film. There is a film. These films can be formed by vacuum deposition, chemical vapor generation, or the like.

Further, when an insulating layer is formed in order to install a control electrode or a circuit, a coating layer that is difficult to form carbon nanofibers is formed thereon. Alternatively, a coating layer (for example, Al ₂ O ₃ or the like) is formed with a coating material that has an insulating property and is difficult to form carbon nanofibers. As a result, the surface of the metal plate is in a state where it is difficult for carbon nanofibers to be generated.

  In the present invention, there is no coating that does not easily form carbon nanofibers, and the surface shape of a large number of minute regions where the metal plate surface is exposed is not particularly limited, and a free curve other than a concave hole by photoetching or the like It includes all convex shapes, concavo-convex shapes, and planar shapes (straight plate surfaces or shapes obtained by chemically reducing the surface) including straight lines. In order to form these minute regions, a sacrificial layer (for example, a resist material) can be used in the photoetching process.

  According to the method of the present invention, the carbon nanofibers may be arranged in a pattern by a printing method (a method in which a binder is mixed with the generated carbon nanofibers and placed in the minute region).

Obtained by casting steel (carbon steel) containing C: 0.35%, Si: 0.20%, Mn: 0.75%, P: 0.015%, S: 0.0098%, sol.Al: 0.020%, N: 0.0018% The cast slab was hot-rolled to a thickness of 3 mm, pickled, decarburized, and cold-rolled to a thickness of 1 mm. Thereafter, annealing was performed to soften the metal plate, and a thin steel plate having a thickness of 0.25 mm was subsequently formed by cold rolling. Decarburization is performed in a hot-rolled sheet in an atmosphere; 20% H ₂ -residual N ₂ , dew point + 20 ° C. for 3 hours, a decarburized layer is formed on the surface of the metal plate, and the C concentration at the center of the metal plate is A higher concentration gradient was applied.

  FIG. 1 shows a method for producing carbon nanofibers. As shown in FIG. 1B, a coating layer 3 (indium oxide) was formed on a metal plate 9 provided with a concentration gradient as shown in FIG. This material is coated with a photoresist as shown in FIG. 4C, exposed and developed to form a portion 4 that is not corroded by etching. As shown in FIG. The concave portion 1 was formed by photoetching. The pitch of the recesses 1 was 250 μm, and the depth of the recesses was 50 μm or less.

  Carbon nanofibers 2 were generated from the metal plate 9 with the recesses 1 formed by plasma CVD. As a result, as shown in FIG. 1 (e), the carbon nanofibers 2 were preferentially generated on the bottom surface of the concave portion 1 of the metal plate and the vicinity thereof, and the fiber generation state of each concave portion was almost uniform. . In addition, the production | generation of the carbon nanofiber was not seen on the surface of the insulating layer 3.

Obtained by casting steel (carbon steel) containing C: 0.35%, Si: 0.20%, Mn: 0.75%, P: 0.015%, S: 0.0098%, sol.Al: 0.020%, N: 0.0018% The cast slab was hot-rolled to a thickness of 3 mm, pickled, decarburized, and cold-rolled to a thickness of 1 mm. Then, annealing was performed to soften the steel sheet, and a thin steel sheet having a thickness of 0.25 mm was subsequently formed by cold rolling. Decarburization is performed in a hot-rolled sheet in an atmosphere; 20% H ₂ -residual N ₂ , dew point + 20 ° C. for 3 hours to form a decarburized layer on the surface layer of the steel sheet, and the C concentration in the central part of the steel sheet is increased. A concentration gradient was applied.

  FIG. 1 shows a method for producing carbon nanofibers. As shown in FIG. 1B, a coating layer 3 (indium oxide) in which carbon nanofibers are difficult to be formed was formed on a steel plate 9 provided with a concentration gradient as shown in FIG. This material is coated with a photoresist as shown in FIG. 4C, exposed and developed to form a portion 4 that is not corroded by etching. As shown in FIG. The concave portion 1 was formed by photoetching. The pitch of the recesses 1 was 250 μm, and the depth of the recesses was 50 μm or less.

  The carbon nanofiber 2 was produced | generated by the process of the thermal CVD method from the steel plate 9 in which this recessed part 1 was formed. As a result, as shown in FIG. 1 (e), carbon nanofibers 2 were preferentially generated on the bottom surface of the concave portion 1 of the steel plate and in the vicinity thereof, and the fiber generation state of each concave portion was almost uniform. In addition, the production | generation of carbon nanofiber was not seen on the surface of the coating layer 3. FIG.

  Carbon steel containing C: 0.35%, Si: 0.20%, Mn: 0.75%, P: 0.015%, S: 0.0098%, sol. Al: 0.020%, N: 0.0018% (hereinafter referred to as Steel A), C: Casting ultra-low carbon steel (hereinafter referred to as steel B) containing 0.0025%, Si: less than 0.01%, Mn: 0.14%, P: 0.01%, S: 0.0028%, sol.Al: 0.0002%, N: 0.0018% The obtained slab was hot-rolled to a thickness of 3 mm, pickled, and cold-rolled to a thickness of 1 mm. Thereafter, only the steel plate made of steel A was annealed to soften the steel plate, and was subsequently made into a thin steel plate having a thickness of 0.25 mm by cold rolling.

  Thereafter, carbon nanofibers were produced in the same manner as in Example 2. However, a Cr layer having a thickness of 1000 mm was formed as a coating layer that is difficult to form carbon nanofibers. As a result, as shown in FIGS. 2 to 5, carbon nanofibers were preferentially generated on the bottom surface of the concave portion of the steel plate and in the vicinity thereof, and the fiber generation state of each concave portion was almost uniform. In addition, the production | generation of carbon nanofiber was hardly seen on the surface of the coating layer which is hard to form carbon nanofiber. In addition, a steel sheet containing 0.35% C (steel A) produces a thick fiber, whereas a steel sheet containing 0.0025% C (steel B) produces a finer fiber with a higher aspect ratio. doing.

  Steel A and steel B having the composition described in Example 3 were cast, and the obtained slab was hot-rolled to a plate thickness of 3 mm, pickled, and cold-rolled to a plate thickness of 1 mm. Thereafter, only the steel plate made of steel A was annealed to soften the steel plate, and was subsequently made into a thin steel plate having a thickness of 0.25 mm by cold rolling.

  The thin steel plate is coated with a photoresist as shown in FIG. 6A, exposed and developed, and as shown in FIG. 6B, the resist is coated with an area of 1 mm × 1 mm for the coating layer through hole. Remained. Further, as shown in FIG. 6 (c), after depositing the Cr peritoneum in a vacuum, the resist was peeled off to form a coating layer through-hole (micro area) 1A. Carbon nanofibers 2 were produced by a thermal CVD process in the coating layer through-hole portion of the metal plate 9 in which the coating layer through-hole 1A was formed, thereby producing a carbon nanoemitter.

After a copper lead electrode with a thickness of 1 mm is placed on the counter electrode of the carbon nanoemitter, a vacuum is drawn to 1 × 10 ^-4 Pa, and a voltage is applied between the carbon nanoemitter and the lead electrode to make IV (voltage-current ) The characteristics were evaluated. The results are shown in FIG. It was confirmed that the carbon nanoemitter according to the present invention emits a field from a low electric field strength of 3 V / μm and has a field emission characteristic of a high current density of 100 μA / mm ² . Furthermore, it was confirmed that the carbon nanoemitter using a steel plate (steel B) containing 0.0025% of C emits a field from an extremely low electric field strength of 0.6 V / μm.

The metal plate which can easily form the carbon nanofiber of the present invention can be used as an element for manufacturing a needle-like emitter electrode of an electron-emitting element at low cost.
The metal plate manufacturing method of the present invention can utilize the metal plate as a manufacturing method.
The nanocarbon emitter of the present invention can be used as an electron-emitting device used in an image display device such as FED.

It is a figure which shows the method of producing | generating a carbon nanofiber by the photoetching method by Example 1, (a) is after decarburization annealing, (b) is after a coating layer coating, (c) is after photoresist application and development, ( d) shows after photo-etching, and (e) shows after plasma CVD or thermal CVD. It is a SEM (scanning electron microscope) photograph which shows the production | generation state of the carbon nanofiber of the steel plate which contains C 0.35%. It is a SEM enlarged photograph which shows the production | generation state of the carbon nanofiber of the hole part of FIG. It is a SEM (scanning electron microscope) photograph which shows the production | generation state of the carbon nanofiber of the steel plate containing C 0.0025%. It is a SEM enlarged photograph which shows the production | generation state of the carbon nanofiber of the hole part of FIG. FIG. 6 is a diagram for explaining a method of patterning and forming carbon nanofibers on the surface of a flat metal plate by a photoresist method and a thermal CVD method according to Example 3, (a) is a photoresist coating process on the metal plate, (b) ) Is a developing step, (c) is a step of coating a coating layer that is difficult to form carbon nanofibers, (d) is a resist stripping step, and (e) is a processing step by a thermal CVD method. It is a figure which shows the IV characteristic of the nanocarbon emitter of Example 3. It is a figure explaining the form of various nanocarbon materials.

Explanation of symbols

1 Recess 1A Through hole (micro area)
2 Carbon nanofiber 3 Insulating layer, coating layer 4 Photoresist 9 Steel plate

Claims (10)

  In a metal plate made of steel containing 1 mass% or less of C in an average concentration in the plate thickness direction, the surface of the metal plate is formed with a large number of minute regions where the metal plate surface is exposed, and other than the minute regions A metal plate that is easy to form carbon nanofibers, wherein a coating layer that is difficult to form carbon nanofibers is formed on the surface of the metal plate.   2. The metal plate that is easy to form carbon nanofibers according to claim 1, wherein the coating layer that is difficult to form carbon nanofibers is a coating layer that has insulating properties and is difficult to form carbon nanofibers.   The metal plate according to claim 1 or 2, wherein a concave hole is formed on the surface of the metal plate in the minute region.   The metal plate which can form the carbon nanofiber of any one of Claims 1-3 in which the decarburization layer is formed in the metal plate surface layer and its vicinity.   Hot rolled a metal plate made of steel containing C in the thickness direction with an average concentration of 1 mass% or less, followed by cold rolling at least once, and annealing at least once as needed to achieve a predetermined thickness In doing so, decarburization annealing is performed as necessary during or after any step after hot rolling to form a coating layer that is difficult to form carbon nanofibers on the surface of the obtained metal plate, and then A carbon nanofiber characterized by forming a large number of micropores penetrating the coating layer that is difficult to form the carbon nanofiber to reach the surface or surface layer of the metal plate, and forming a large number of microregions where the metal plate surface is exposed. The manufacturing method of the metal plate which is easy to form.   6. The method for producing a metal plate that easily forms carbon nanofibers according to claim 5, wherein the coating layer that is difficult to form carbon nanofibers is a coating layer that has insulating properties and is difficult to form carbon nanofibers. .   7. The metal that easily forms carbon nanofibers according to claim 5 or 6, wherein, in the step of forming the carbon nanofibers, after forming an insulating layer, a coating layer that is difficult to form carbon nanofibers is formed. A manufacturing method of a board.   8. The metal easily forming carbon nanofibers according to claim 5, wherein the step of forming a large number of minute regions with the metal plate surface exposed on the surface of the metal plate is a photoetching step. A manufacturing method of a board.   9. The method of manufacturing a metal plate that easily forms carbon nanofibers according to claim 8, wherein the photoetching step forms a concave hole on the surface of the metal plate.   The steel plate which is easy to form the carbon nanofiber according to any one of claims 1 to 4, or the metal plate which is easy to form the carbon nanofiber manufactured by the method according to claims 5 to 9, using a thermal CVD method or plasma CVD. Nanocarbon emitters with excellent discharge characteristics, characterized in that carbon nanofibers are formed in a minute region on the surface of a metal plate by a plasma method or a plasma arc method.