Powder surface film-forming apparatus and method for producing coated powder

Abstract

The present disclosure provides a powder surface film-forming device, which makes it possible to reduce the aggregation of a powder by disintegrating aggregates of the powder at a proper timing during the delivery of the powder when the formation of a film on the surfaces of the powder is performed by a dry-mode process and, as a result, enables the formation of a film having a uniform thickness on the surface of each particle of a raw material powder, and can achieve satisfactory adhesion efficiency of a thin film. The powder surface film-forming device 100 is provided with a powder delivery mechanism 3 which has delivery passages 8-2 to 8-5 for a powder 15, film formation units 6-1 to 6-4 which are respectively arranged at positions respectively facing passage surfaces of the delivery passages and in which a portion of each of the passage surfaces serves as a film formation area, disintegration mechanisms 2-1 to 2-3 which are used for disintegrating aggregates of the powder, and a relay mechanism 2 which delivers the powder from the delivery passages to the disintegration mechanisms and transfers the disintegrated powder to another delivery passage, in which the delivery passages and the relay mechanism together constitute a single circulation passage 16 and repeatedly perform the formation of a film on the surface of each particle of the powder and the disintegration of the aggregates of the powder during circulating delivery of the powder through the circulation passages.

Description

Technical Field

[0001] The present disclosure relates to a powder surface film-forming apparatus for uniformly forming a thin film on the surface of each particle of powder and a method for manufacturing coated powder.

Background Art

[0002] In order to impart new functions to powder, a thin film may be formed on the surface of the particles. As a technique for forming a thin film on the particle surface by a vapor deposition method (dry method), there is a sputtering method. Various film-forming apparatuses for powder using the sputtering method have been proposed (see, for example, Patent Documents 1 to 6).

[0003] In Patent Document 1, an apparatus is proposed in which a sputtering source is provided in a rotatable and evacuable barrel. A method is described in which raw material powder of metal, ceramics, or plastic is charged into the rotating barrel, and the raw material powder is coated while forming a fluidized bed of the powder by rotating the barrel. Based on the above-described barrel type mechanism, an improvement has been proposed to efficiently form a film on the surface of the raw material powder by enhancing the stirring efficiency of the powder in the rotating container.

[0004] In Patent Document 2, an apparatus having a polygonal shape of a rotating container is proposed. By rotating or pendulum-operating the container and sputtering while stirring the raw material powder charged inside the container, uniform coating of the raw material powder is enabled.

[0005] Patent Documents 3 and 4 disclose an apparatus in which a stirring plate, a scraper, and rod-shaped powder aggregation suppressing components are installed in a rotating container to promote stirring of the raw material powder and sputter the raw material powder equally.

[0006] In Patent Document 5, a film-forming apparatus of a method different from the barrel type is proposed, and it is shown that a film can be efficiently formed on the surface of the powder by efficiently stirring the powder by repeating conveyance and dropping in a powder conveyance container having a bottom surface.

[0007] In the apparatus of FIG. 1 of Patent Document 6, the vacuum chamber 110 surrounds the coating material vaporization source 120 and the substrate exposure apparatus embodied by the vibrating bed 130. The powder substrate material 132 is disposed in a rotatable container 344 operably connected to the vibrator 140. In the operation of the coating apparatus 100, the substrate material 132 undergoes a substantially helical motion represented by arrows A1 and A2 in FIG. 1. The flow 152 of the vaporized coating material is discharged from the coating material vaporization source 120, reaches the substrate material 132, and coats it. Further, in the apparatus of FIG. 3A of Patent Document 6, the vacuum chamber 310 encloses both the coating material vaporization source 320 and the substrate exposure apparatus embodied by the vibrating conveyor coater. The vibrating conveyor coater 330 preferably has four conveyors 371, 372, 373, and 374, which are arranged such that the powder of the substrate material 332 circulates effectively counterclockwise as indicated by arrow A5. The powder circulates along this path and is effectively mixed so that the exposure to the vaporized coating material becomes uniform. Efficient mixing is also performed at the ends of each conveyor when the powder falls like a waterfall from one tray to the next. In the apparatus of FIG. 1 or FIG. 3A of Patent Document 6, the powder is circulated and transferred by the vibrator 140 (FIG. 1) or the vibrating conveyor coater 330 (FIG. 3A) connected to the container 344, and while mixing the powder during that time, it is a device for coating a thin film on the surface of the powder.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0009] By the way, when the present inventors observed the powder formed by the sputtering method, it was found that the particles with a film formed and the particles without a film were mixed, and further, uneven film adhesion was confirmed for each particle even in the particles with a film formed. This was particularly prominent in powders with a particle diameter of 100 μm or less. And during the inventors' further study, it was identified that the aggregation of the powder is one of the causes of uneven film adhesion. Sputtered particles reach the surface of the particles existing on the surface of the powder. And if the powder is not aggregated, when the powder is stirred and mixed, the particles existing inside the surface of the powder are exposed to the surface of the powder, and a film is formed on the surface of the particles. As this is repeated, a thin film is uniformly formed on the surface of each particle of the powder. However, if the powder is aggregated, sputtered particles do not reach the inner region of the aggregated powder, resulting in uneven film adhesion.

[0010] When there is uneven film adhesion, for example, in the particles of the paste material used in electronic devices, the electrical characteristics deteriorate, and in the positive electrode material used in all-solid-state batteries, the coating property is poor, resulting in a decrease in durability. Also, in the case of a catalyst, the performance efficiency deteriorates.

[0011] The causes of powder aggregation include intermolecular forces and electrostatic forces, etc. However, the main causes are two types: aggregation due to the surface tension of moisture on the particle surface (hereinafter referred to as liquid bridging) and aggregation where the film formed connects between particles (hereinafter referred to as film bridging). In particular, the smaller the particle diameter of the powder, the larger the specific surface area, and it cannot be loosened by its own weight. Therefore, it has been found that solving the above two causes is important for achieving uniform film formation on the powder.

[0012] Now, the inventions described in Patent Documents 2 to 6 are technologies that have been studied regarding stirring operations with the main focus on improving the efficiency of film formation, and are effective means for efficiently forming a film on powder. However, the problem of aggregation discovered by the present inventors, that is, as long as aggregation is not solved, a uniform film cannot be formed on each particle of the powder after film formation, is actually not studied in Patent Documents 2 to 6, and the film uniformity of the coated powder could not be said to be good.

[0013] On the other hand, for liquid crosslinking, measures such as removing moisture on the particle surface by heating the powder or removing moisture by decomposing moisture on the particle surface by reverse sputtering can be considered. However, even if these are carried out, moisture removal is insufficient in powders with a large specific surface area, and it is difficult to completely prevent powder aggregation.

[0014] In addition, since the powder film-forming apparatus has a low production capacity due to the particularity of its mechanism, this is also an issue to be solved. Since Patent Documents 1 to 4 all have a barrel-type mechanism, they are batch production and there are restrictions on the container, and there are mechanical constraints in increasing mass productivity. Also, the maintainability is poor. Patent Documents 5 and 6 also result in batch production, and the powder loading capacity depends on the size of the conveying device and the size of the sputtering target.

[0015] Therefore, an object of the present disclosure is to reduce powder aggregation by crushing powder aggregates at an appropriate timing during the conveyance of the powder when performing powder surface film formation by a dry method. As a result, a uniform film thickness can be formed on the surface of each particle of the raw material powder, and a powder surface film-forming apparatus capable of achieving good film adhesion efficiency can be provided. Another object of the present disclosure is to provide a manufacturing method capable of manufacturing a coated powder having a uniform film thickness formed on the surface of each particle of the raw material powder while achieving good film adhesion efficiency.

Means for Solving the Problems

[0016] As a result of intensive studies, the present inventors have found that liquid crosslinking and film crosslinking are major factors in powder aggregation, and that stirring is insufficient to loosen powder aggregation. They have also found that the above problems can be solved by introducing a mechanism for crushing powder aggregates. In addition, they have noticed that the thickness of the film crosslinking significantly affects the success of aggregate crushing. By circulating the powder and repeating film formation and crushing of the powder aggregates at least once per revolution by passing through the crushing mechanism for the powder aggregates, the present inventors have found that the above problems can be solved, and have completed the present invention.

[0017] The powder surface film-forming apparatus according to the present invention is an apparatus for forming a film on the surface of each particle of powder, and includes a powder transport mechanism having at least one transport path for the powder, a film-forming unit disposed at a position facing at least one road surface of the transport path and having all or a part of the road surface as a film-forming region, a crushing mechanism for crushing aggregates of the powder, and a relay mechanism for sending the powder from at least one of the transport paths to the crushing mechanism and returning the powder after the crushing process to the transport path or transferring it to another transport path. The powder conveying mechanism has a vibrating feeder. The transport path and the relay mechanism constitute a single circulation path, and it is characterized in that while circulating the powder in the circulation path, film formation on the surface of each particle of the powder and crushing of the powder aggregates are repeated. By having a vibrating feeder, the powder can be spread in a uniform thickness in the conveying path and conveyed while being agitated. Also, the powder can be conveyed even if the conveying path is upwardly inclined, and it is easy to form a circulation path.

[0018] Further, the powder surface film-forming apparatus according to the present invention is an apparatus for forming a film on the surface of each particle of the powder, and includes a powder conveying mechanism having at least one conveying path for the powder, a film-forming unit disposed at a position facing at least one road surface of the conveying path and having all or a part of the road surface as a film-forming region, a crushing mechanism for crushing aggregates of the powder, a relay mechanism for sending the powder from at least one of the conveying paths to the crushing mechanism and returning the powder after the crushing process to the conveying path or transferring it to another conveying path, a film-forming chamber, at least one preliminary chamber communicating with the film-forming chamber via an opening / closing door, a powder supply mechanism, and a powder discharge mechanism. The conveying path and the relay mechanism constitute a single circulation path. The powder conveying mechanism, the film-forming unit, the crushing mechanism, the relay mechanism, and the circulation path are disposed in the internal space of the film-forming chamber, and the powder supply mechanism and the powder discharge mechanism are disposed in the internal space of the preliminary chamber. While the powder is circulated and conveyed in the circulation path, film formation on the surface of each particle of the powder and crushing of the aggregates of the powder are repeatedly performed. Without releasing the vacuum of the film-forming chamber to the atmosphere, powder supply into the film-forming chamber in vacuum, film formation on each particle of the powder, crushing of the aggregates of the powder, and powder discharge from the film-forming chamber in vacuum can be performed. As a result, it becomes possible to manufacture coated powder with high efficiency close to continuous film formation.

[0019] Moreover, the powder surface film-forming apparatus according to the present invention is an apparatus for forming a film on the surface of each particle of powder, and includes a powder conveying mechanism having at least one conveying path for the powder, a film-forming unit disposed at a position facing at least one road surface of the conveying path and having all or part of the road surface as a film-forming region, a crushing mechanism for crushing aggregates of the powder, and a relay mechanism for sending the powder from at least one of the conveying paths to the crushing mechanism and returning the powder after the crushing treatment to the conveying path or transferring it to another conveying path. The conveying path and the relay mechanism constitute a single circulation path. The powder conveying mechanism is configured to annularly arrange a plurality of conveying paths along the conveying direction of the powder, and in all of the plurality of conveying paths, the starting point of the conveying direction of the adjacent conveying path is arranged below the end point of the conveying direction of the conveying path. The relay mechanism is arranged at a position for receiving the powder falling from the end point of the conveying direction of the conveying path, and supplies the powder crushed by the crushing mechanism to the starting point of the conveying direction of the adjacent conveying path. The relay mechanism is provided at least at one location between the plurality of conveying paths, and is characterized in that while circulating and conveying the powder in the circulation path, film formation on the surface of each particle of the powder and crushing of aggregates of the powder are repeatedly performed. The aggregates of the powder can be crushed by the number of relay mechanisms provided each time the circulation path makes one round.

[0020] Moreover, the powder surface film-forming apparatus according to the present invention is an apparatus for forming a film on the surface of each particle of the powder, and includes a powder conveying mechanism having at least one conveying path for the powder, a film-forming unit disposed at a position facing at least one road surface of the conveying path and having all or part of the road surface as a film-forming region, a crushing mechanism for crushing aggregates of the powder, and a relay mechanism for sending the powder from at least one of the conveying paths to the crushing mechanism and returning the powder after the crushing process to the conveying path or transferring it to another conveying path. The conveying path and the relay mechanism constitute a single circulation path. The conveying path has a constant spiral surface and a step portion between the upper end portion and the lower end portion of the constant spiral surface formed by spiral circulation. The film-forming unit has the entire constant spiral surface as the film-forming region. The powder conveying mechanism conveys the powder to the spiral upper side of the constant spiral surface. The relay mechanism disposes the crushing mechanism at a position for receiving the powder falling from the upper end portion of the constant spiral surface and supplies the powder crushed by the crushing mechanism to the lower end portion of the constant spiral surface. While the powder is circulated and conveyed in the circulation path, film formation on the surface of each particle of the powder and crushing of aggregates of the powder are repeatedly performed. By conveying the powder so as to spiral around the constant spiral surface, the aggregates of the powder can be crushed each time the powder passes through the step portion.

[0021] Further, the powder surface film-forming apparatus according to the present invention is an apparatus for forming a film on the surface of each particle of powder, and includes a powder conveying mechanism having at least one conveying path for the powder, a film-forming unit disposed at a position facing at least one road surface of the conveying path and having all or part of the road surface as a film-forming region, a crushing mechanism for crushing aggregates of the powder, and a relay mechanism for sending the powder from at least one of the conveying paths to the crushing mechanism and returning the powder after the crushing process to the conveying path or transferring it to another conveying path. The conveying path and the relay mechanism constitute a single circulation path. The powder conveying mechanism arranges a plurality of conveying paths along the upstream side to the downstream side in the conveying direction of the powder, and has a relationship in which the starting point in the conveying direction of the adjacent conveying path is disposed below the end point in the conveying direction of the conveying path. The relay mechanism disposes the crushing mechanism at a position for receiving the powder falling from the end point in the conveying direction of the conveying path, and supplies the powder crushed by the crushing mechanism to the starting point in the conveying direction of the adjacent conveying path. The relay mechanism is provided at least at one location between the plurality of conveying paths, and includes a powder supply hopper disposed above the starting point of the most upstream of the plurality of conveying paths, a powder discharge hopper disposed below the end point of the most downstream of the plurality of conveying paths, and a powder return mechanism for sending the powder discharged from the powder discharge hopper to the powder supply hopper. While the powder is circulated and conveyed in the circulation path, film formation on the surface of each particle of the powder and crushing of aggregates of the powder are repeatedly performed. The aggregates of the powder can be crushed by the number of relay mechanisms provided each time the circulation path makes one round.

[0022] Further, the powder surface film-forming apparatus according to the present invention is an apparatus for forming a film on the surface of each particle of powder, and includes a powder conveying mechanism having at least one conveying path for the powder, a film-forming unit disposed at a position facing at least one road surface of the conveying path and having all or a part of the road surface as a film-forming region, a crushing mechanism for crushing aggregates of the powder, and a relay mechanism for sending the powder from at least one of the conveying paths to the crushing mechanism and returning the powder after the crushing process to the conveying path or transferring it to another conveying path. The conveying path and the relay mechanism constitute a single circulation path. The crushing mechanism is a mechanical crushing mechanism, and the mechanical crushing mechanism has a sieve for sieving the powder, and the vibration of the sieve has a vibration component perpendicular to the mesh passing direction of the powder, or has a vibration component perpendicular to the mesh passing direction of the powder and a vibration component parallel to the mesh passing direction of the powder, and the acceleration of the vibration of the sieve is 10 m / s 2 or more. While circulating and conveying the powder in the circulation path, film formation on the surface of each particle of the powder and crushing of aggregates of the powder are repeatedly performed. If the crushing mechanism is a method in which pressure is applied to the powder, aggregation will be promoted. By suppressing the pressure applied to the powder and vibrating it so that a shearing force is applied to the powder, the efficiency of crushing can be increased. By setting the acceleration of the vibration of the sieve to 10 m / s 2 or more, sufficient crushing force can be applied to the aggregates of the powder.

[0023] Also, the powder surface film-forming apparatus according to the present invention is an apparatus for forming a film on the surface of each particle of powder, and includes a powder conveying mechanism having at least one conveying path for the powder, a film-forming unit disposed at a position facing at least one road surface of the conveying path and having all or part of the road surface as a film-forming region, a crushing mechanism for crushing aggregates of the powder, and a relay mechanism for sending the powder from at least one of the conveying paths to the crushing mechanism and returning the powder after the crushing treatment to the conveying path or transferring it to another conveying path. The conveying path and the relay mechanism constitute a single circulation path, and further include a film-forming chamber, at least one preliminary chamber communicating with the film-forming chamber via an opening / closing door, a powder supply mechanism, and a powder discharge mechanism. The powder conveying mechanism, the film-forming unit, the crushing mechanism, the relay mechanism, and the circulation path are disposed in the internal space of the film-forming chamber. The conveying path has n (where n ≥ 2) regular helical surfaces having the same central axis and arranged adjacent to each other, and n step portions between the upper end portion of one regular helical surface and the lower end portion of the adjacent regular helical surface. The film-forming unit has the entire n regular helical surfaces arranged adjacent to each other as the film-forming region. The powder conveying mechanism conveys the powder to the spiral upper side of the regular helical surface. The relay mechanism disposes the crushing mechanism at a position for receiving the powder falling from the upper end portion of the regular helical surface at at least one of the step portions, and supplies the powder crushed by the crushing mechanism to the lower end portion of the regular helical surface. The powder supply mechanism is disposed in the internal space of the preliminary chamber, and supplies the powder before film formation to the regular helical surface at at least one of the step portions when the opening / closing door is open. The powder discharge mechanism is disposed in the internal space of the preliminary chamber, and moves to a position for receiving the powder falling from the upper end portion of the regular helical surface at at least one of the step portions when the opening / closing door is open to collect the powder. While the powder is circulated and conveyed in the circulation path, film formation on the surface of each particle of the powder and crushing of aggregates of the powder are repeatedly performed. By conveying the powder so as to spiral around the regular helical surface, crushing can be performed each time the step portion is passed through.In addition, without releasing the vacuum in the film-forming chamber to the atmosphere, it is possible to supply powder into the film-forming chamber in a vacuum, form a film on each particle of the powder, crush aggregates of the powder, and carry out the powder out of the film-forming chamber in the vacuum. As a result, it becomes possible to manufacture coated powder with high efficiency close to continuous film formation.

[0024] In the powder surface film-forming apparatus according to the present invention, the film-forming unit is preferably a film-forming apparatus by any one of metalorganic chemical vapor deposition, plasma-excited chemical vapor deposition, sputtering, ion plating, vapor deposition, ion beam, and atomic beam, or a combination of two or more of these.

[0027] The manufacturing method of the coated powder according to the present invention is a method for manufacturing a coated powder in which a thin film is coated on the surface of each particle of the powder, and includes: a first step of circulating and transporting the powder through a circulation path including a transport path; and a second step of supplying a film-forming material in a film-forming state from a film-forming unit that is disposed at a position facing the road surface of the transport path and that defines all or part of the road surface as a film-forming region, to form a film on the surface of at least the particles located in the surface layer of the powder, while the powder is being transported on the transport path; and a third step of crushing aggregates of the powder at at least one location in the circulation path. The conveying path has a vibrating feeder, and the powder is conveyed by the operation of the vibrating feeder. During the circulating and transporting of the powder, film formation on the surface of each particle of the powder and crushing of aggregates of the powder are repeatedly performed.

[0028] In the manufacturing method of the coated powder according to the present invention, it is preferable to perform the crushing treatment in the third step at least once while the thickness of the thin film formed in the second step is 20 nm or less. It is possible to efficiently crush aggregates of the powder, and as a result, the film can be formed more uniformly on each particle of the powder.

[0029] In the manufacturing method of the coated powder according to the present invention, the film-forming method by the film-forming unit is preferably any one of metalorganic chemical vapor deposition, plasma-enhanced chemical vapor deposition, sputtering, ion plating, vapor deposition, ion beam, and atomic beam, or a combination of two or more of these methods.

Advantages of the Invention

[0030] According to the present disclosure, when forming a film on the surface of powder by a dry method, aggregation of the powder is reduced by crushing aggregates of the powder at an appropriate timing during the conveyance of the powder. As a result, a film with a uniform film thickness can be formed on the surface of each particle of the raw material powder, and a powder surface film forming apparatus capable of achieving good adhesion efficiency of the thin film can be provided. Further, according to the present disclosure, a manufacturing method capable of manufacturing a coated powder having a uniform film thickness formed on the surface of each particle of the raw material powder while achieving good adhesion efficiency of the thin film can be provided.

Brief Description of the Drawings

[0031]

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Mode for Carrying Out the Invention

[0032] Hereinafter, embodiments of the present invention will be shown and described in detail, but the present invention is not construed as being limited to these descriptions. As long as the effects of the present invention are achieved, the embodiments may be variously modified. In the drawings, in each apparatus, parts with the same name are given the same reference numeral regardless of their shape.

[0033] The powder surface film-forming apparatuses 100, 200, 300, 400 according to the present embodiment are apparatuses for forming a film on the surface of each particle of the powder 15, and include a powder conveying mechanism 3 having at least one of the conveying paths 8-2 to 8-5, 38, 58, 78-1 to 78-2 of the powder 15; a film-forming unit 6-1 to 6-4, 36, 56, 76-1 to 76-2 disposed at a position facing at least one road surface of the conveying paths 8-2 to 8-5, 38, 58, 78-1 to 78-2, and having all or part of the road surface as a film-forming region; a crushing mechanism 2-1 to 2-3, 32, 52, 72-1 to 72-2 for crushing the aggregates of the powder 15; and a relay mechanism 2 that sends the powder from at least one of the conveying paths 8-2 to 8-5, 38, 58, 78-1 to 78-2 to the crushing mechanism, and returns the powder 15 after the crushing process to the conveying path or transfers it to another conveying path. The conveying paths 8-2 to 8-5, 38, 58, 78-1 to 78-2 and the relay mechanism 2 constitute a single circulation path 16, and while the powder 15 is circulated and conveyed in the circulation path 16, film formation on the surface of each particle of the powder 15 and crushing of the aggregates of the powder are repeatedly performed.

[0034] Four modes can be exemplified for the powder surface film-forming apparatus according to the present embodiment depending on the form of the circulation path 16. Each apparatus will be described hereinafter.

[0035] (First mode: A mode in which the circulation path is arranged in a ring shape) The powder surface film-forming apparatus 100 according to the present embodiment will be described with reference to FIGS. 1 to 9. The film-forming apparatus 100 of the present embodiment has a preliminary chamber 4-1 and a film-forming chamber 4-2. A second opening / closing door 9-2 is provided between the preliminary chamber 4-1 and the film-forming chamber 4-2, and the opening and closing between the chambers can be performed. The preliminary chamber 4-1 and the film-forming chamber 4-2 communicate with each other via the second opening / closing door 9-2.

[0036] In the internal space of the preliminary chamber 4-1, a powder supply mechanism 11 and a powder discharge mechanism 12 are arranged. The powder supply mechanism 11 has an ultrasonic sieve hopper 1-1, an ultrasonic sieve 1-1a, a trough 8-1, and a vibratory feeder 3-1. Specifically, in the internal space of the preliminary chamber 4-1, the ultrasonic sieve hopper 1-1 is arranged. The ultrasonic sieve 1-1a is mounted on the ultrasonic sieve hopper 1-1. The trough 8-1 is arranged below the ultrasonic sieve hopper 1-1, and the vibratory feeder 3-1 is connected to the trough 8-1. A heater or a reverse sputtering mechanism (not shown) is installed in the preliminary chamber 4-1, and moisture in the powder can be removed by operating the heater or the reverse sputtering mechanism. The preliminary chamber 4-1 is evacuated by an exhaust pump 7-2 such as a rotary pump, an oil diffusion pump, or a turbo molecular pump. The preliminary chamber 4-1 is connected to the glove box 10 via a first opening / closing door 9-1. Further, the powder discharge mechanism 12 has a discharge hopper 1-3, a trough 8-6, and a vibratory feeder 3-6. Specifically, in the preliminary chamber 4-1, the discharge hopper 1-3 is arranged. Also, the trough 8-6 is arranged, and the vibratory feeder 3-6 is connected to the trough 8-6. The opening of the discharge hopper 1-3 is arranged below the end of the trough 8-6 on the side of the first opening / closing door 9-1.

[0037] In the internal space of the film forming chamber 4-2, a powder transfer mechanism 3, film forming units 6-1 to 6-4, crushing mechanisms 2-1 to 2-3, a relay mechanism 2, and a circulation path 16 are arranged. The film forming chamber 4-2 is evacuated by an exhaust pump 7-1 such as a rotary pump, an oil diffusion pump, or a turbo molecular pump.

[0038] The powder conveying mechanism 3 has troughs and vibration feeders 3-2 to 3-5 as conveying paths 8-2 to 8-5. When the vibration feeder is operated, the powder is evenly covered and conveyed on the conveying path. It is important that the conveying path is filled with powder. The reason is that when a film adheres to the surface of the conveying path, the adhesion efficiency decreases, and the film on the surface of the conveying path hinders the conveyance of the powder, leading to a decrease in productivity. Vibration feeders 3-2 to 3-5 are respectively connected to the conveying paths 8-2 to 8-5. Here, it is preferable to have a cooling mechanism for cooling the conveying paths 8-2 to 8-5. Also, it is preferable to have a cooling mechanism for cooling the housings of the electromagnetic coils of the vibration feeders 3-2 to 3-5. The vibration feeders 3-2 to 3-5 are continuously operated when conveying the powder 15 in the circulation path 16. At this time, it is preferable to provide a cooling mechanism to prevent damage to the electromagnetic coils of the vibration feeders 3-2 to 3-5. As the cooling mechanism, the installation of a water-cooled plate using cooling water is used. The vibration feeder can be either piezo or electromagnetic.

[0039] In FIG. 1, there are four powder conveyance paths 8-2 to 8-5, and the conveyance paths 8-2 to 8-5 are arranged in an annular and rectangular shape along the powder conveyance direction. It is also possible to arrange three conveyance paths in an annular or triangular shape along the powder conveyance direction, or to arrange N conveyance paths in an annular or N-sided shape along the powder conveyance direction. Here, the powder conveyance mechanism 3 has a relationship in which, at all of the plurality of conveyance paths, the starting point of the conveyance direction of the adjacent conveyance path is arranged below the end point of the conveyance direction of the conveyance path. The starting point of the conveyance direction of the adjacent conveyance path 8-3 is arranged below the end point of the conveyance direction of the conveyance path 8-2, and between them, a crushing mechanism 2-1 for crushing the aggregate of the powder 15 is arranged. Since the powder surface film forming apparatus 100 has such an arrangement relationship, the relay mechanism 2 sends the powder 15 from the conveyance path 8-2 to the crushing mechanism 2-1 and transfers the powder 15 after the crushing process to another conveyance path 8-3. That is, the relay mechanism 2 arranges the crushing mechanism 2-1 at a position to receive the powder 15 falling from the end point of the conveyance direction of the conveyance path 8-2, and supplies the powder 15 crushed by the crushing mechanism 2-1 to the starting point of the conveyance direction of the adjacent conveyance path 8-3. Similarly, the starting point of the conveyance direction of the adjacent conveyance path 8-4 is arranged below the end point of the conveyance direction of the conveyance path 8-3, and between them, a crushing mechanism 2-2 is arranged and a relay mechanism 2 is provided. Similarly, the starting point of the conveyance direction of the adjacent conveyance path 8-5 is arranged below the end point of the conveyance direction of the conveyance path 8-4, and between them, a crushing mechanism 2-3 is arranged and a relay mechanism 2 is provided. Although the starting point of the conveyance direction of the adjacent conveyance path 8-2 is arranged below the end point of the conveyance direction of the conveyance path 8-5, no crushing mechanism is arranged between them. Therefore, no relay mechanism is provided. Thus, in FIG. 1, the relay mechanism 2 is installed at three locations between the four conveyance paths. FIG. 1 shows a form in which three crushing mechanisms are installed between the four conveyance paths, but the number may be two or one. The more the number of crushing mechanisms provided, the more opportunities there are to crush the aggregation of the powder. Also, when no crushing mechanism is provided between the conveyance path and the adjacent conveyance path, the powder is transferred by directly falling from the conveyance path to the adjacent conveyance path, and such a form can be said to be a modified example of the conveyance of the powder by the conveyance path.The reason for not arranging a crushing mechanism between the transport path 8-5 and the transport path 8-2 is to enable the insertion of the trough 8-6 as the powder discharge mechanism 12 when discharging the powder from the film forming chamber 4-2.

[0040] The relay mechanisms 2 installed at three locations between the transport paths 8-2 to 8-5 and the four transport paths constitute a single circulation path 16. With such a configuration, while the powder 15 is circulated and transported in the circulation path 16, film formation on the surface of each particle of the powder 15 and crushing of the powder aggregates can be repeatedly performed.

[0041] As a modified example of the powder surface film forming apparatus 100 shown in FIG. 1, one annular transport path may be arranged. One annular transport path has a relationship in which the starting point of the transport direction of the adjacent transport path is arranged below the end point of the transport direction of the transport path. At the position where the starting point of the transport direction of the transport path is arranged below the end point of the transport direction of the transport path, a crushing mechanism for crushing the powder aggregates is arranged therebetween. The relay mechanism sends the powder from the transport path to the crushing mechanism and returns the powder after the crushing process to the transport path. That is, the relay mechanism 2 arranges the crushing mechanism at a position to receive the powder falling from the end point of the transport direction of the transport path and supplies the powder crushed by the crushing mechanism to the starting point of the transport direction of the transport path.

[0042] The crushing mechanisms 2-1 to 2-3 are mechanical crushing mechanisms as shown in FIG. 9. The mechanical crushing mechanism has a sieve for sieving the powder 15. The vibration of the sieve preferably has a vibration component perpendicular to the mesh passing direction T of the powder, or preferably has a vibration component perpendicular and a vibration component parallel to the mesh passing direction of the powder. Here, the perpendicular direction V to the mesh passing direction of the powder means the front-back, left-right direction of the vibration direction of the sieve with respect to the paper surface of FIG. 9 with respect to the passing direction of the powder. The parallel direction P to the mesh passing direction of the powder means the up-down direction of the vibration direction of the sieve with respect to the paper surface of FIG. 9 with respect to the passing direction of the powder. When the vibration of the sieve has a vibration component perpendicular and a vibration component parallel to the mesh passing direction of the powder, the mesh surface of the sieve may be inclined with respect to the passing direction of the powder. In this case, the powder passes through the mesh while moving on the mesh surface. Also, depending on the vibration method of the sieve, even if the mesh surface of the sieve is not inclined with respect to the passing direction of the powder, it may have a vibration component perpendicular and a vibration component parallel to the mesh passing direction of the powder. In the crushing mechanisms 2-1 to 2-3, a shearing force is generated between the particles of the powder due to the stress when the powder containing aggregates hits the unevenness of the sieve mesh and the frictional force between the mesh and the powder. The force of the vertical component of the self-weight of the powder mainly affects the crushing. The crushing mechanisms 2-1 to 2-3 do not include crushing that compresses and crushes the object to be crushed such as a ball mill or a vibration mill. The acceleration of the vibration of the sieve is 10 m / s 2 or more is preferable. When the vibration of the sieve has a vibration component perpendicular and a vibration component parallel to the mesh passing direction of the powder, the vibration in the amplitude direction of the vibration of the sieve obtained by synthesizing the vertical component and the parallel component is 10 m / s 2 or more is preferably satisfied. The sieve is preferably an ultrasonic sieve. The vibration frequency of the sieve is preferably 20 kHz or more, and more preferably 33 to 38 kHz. Here, the reason for setting the acceleration to 10 m / s 2 or more is related to the acceleration of the vibration of the sieve and the crushing force of the aggregates. When the acceleration of the vibration of the sieve is 10 m / s 2 or more, the crushing of the aggregates was efficiently performed. In the case of an ultrasonic sieve, the acceleration of the vibration of the sieve is 10 to 500 m / s 2It was easy to do. The method for measuring the acceleration of the vibration of the sieve is exemplified by attaching the vibration measuring instrument VM-82A of RION Co., Ltd. to the frame of the sieve for measurement. The propagation efficiency varies depending on how the element that generates vibration is attached to the sieve, and the acceleration of the vibration of the sieve also varies. As a result, the obtained crushing force varies. Therefore, even if it is set to a frequency of a predetermined value or higher, a high acceleration is not necessarily obtained.

[0043] The crushing mechanisms 2-1 to 2-3 may use a shear crusher that crushes powder aggregation when discharging the powder put into the cylindrical tube from the gap by bringing at least one of the bottom plate and the cylindrical tube closer to a bottom plate horizontally arranged with a slight gap on one end side of the cylindrical tube and vibrating at least one of them in the horizontal direction, in addition to the sieve shown in FIG. 9.

[0044] The ultrasonic sieve 1-1a preferably has an acceleration of vibration of the sieve of 10 m / s 2 or more.

[0045] The film forming units 6-1 to 6-4 are arranged at positions facing the road surface for each of the transport paths 8-2 to 8-5, and all or part of the road surface is a film forming region. The road surface is the transport surface of the trough. The film forming units 6-1 to 6-4 are preferably film forming apparatuses by any one of metalorganic chemical vapor deposition, plasma enhanced chemical vapor deposition, sputtering, ion plating, vapor deposition, ion beam, atom beam, or a combination of two or more of these. When the film forming units 6-1 to 6-4 are sputtering film forming apparatuses, the cathodes are arranged at positions facing the road surface of the transport paths 8-2 to 8-5. When it is a sputtering film forming apparatus, it is preferably a film forming apparatus of DC-magnetron, DC-pulse magnetron or RF-magnetron. A supply pipe for process gas is introduced into each of the film forming units 6-1 to 6-4. The supply pipe for process gas may be introduced into the film forming chamber 4-2.

[0046] Next, a method for manufacturing coated powder using the powder surface film-forming apparatus 100 will be described. The method for manufacturing coated powder according to the present embodiment is a method for manufacturing coated powder in which a thin film is coated on the surface of each particle of the powder. The method includes a first step of circulating and transporting the powder 15 by a circulation path 16 including transport paths 8-2 to 8-5, and a second step of supplying a film-forming material in a film-forming state from film-forming units 6-1 to 6-4, which are arranged at positions facing the road surface of the transport paths 8-2 to 8-5 and in which all or part of the road surface is a film-forming region, to form a film on the surface of at least the particles located in the surface layer of the powder 15. The method also includes a third step of crushing the aggregates of the powder 15 at at least one location in the circulation path 16, and during the circulating and transporting of the powder 15, the film formation on the surface of each particle of the powder 15 and the crushing of the aggregates of the powder 15 are repeatedly performed. Here, as shown in FIG. 1, the circulation path 16 includes troughs as the transport paths 8-2 to 8-5, a dropping path where the powder drops between the troughs, and a sieving path of ultrasonic sieves as the crushing mechanisms 2-1 to 2-3 arranged in the middle of the dropping path. Here, the first step and the third step may be performed simultaneously. Further, the first step, the second step, and the third step may be performed simultaneously.

[0047] (Previous step) As shown in Fig. 2, open the first opening / closing door 9-1, move the trough 8-1 into the glove box 10, and fill the ultrasonic sieve hopper 1-1 with the powder 15. For filling the powder, the preliminary chamber 4-1 may be opened to the atmosphere for filling. Also, when it is inconvenient for the powder 15 to be exposed to the atmosphere, the glove box 10 may be used to fill it in an inert gas atmosphere. Next, as shown in Fig. 3, return the trough 8-1 to the preliminary chamber 4-1, close the first opening / closing door 9-1, evacuate the preliminary chamber 4-1, and dry the powder 15. The drying may be accelerated by further operating a heater or a reverse sputtering mechanism (not shown). Next, operate the ultrasonic sieve 1-1a to drop the powder 15 in the ultrasonic sieve hopper 1-1 onto the entire surface of the trough 8-1. The film-forming chamber 4-2 is evacuated. After removing moisture, as shown in Fig. 4, the second opening / closing door 9-2 is opened, and the trough 8-1 is brought close to the transport path 8-2. Operate the vibrating feeder 3-1 to transport the powder on the trough 8-1 to the transport path 8-2. At this time, operate the vibrating feeders 3-2 to 3-5 and the crushing mechanisms 2-1 to 2-3. As a result, the powder transported to the transport path 8-2 is spread to the transport paths 8-3 to 8-5. Next, as shown in Fig. 5, return the trough 8-1 into the preliminary chamber 4-1 and close the second opening / closing door 9-2. If the powder 15 is evenly spread to the transport paths 8-2 to 8-5, the film-forming operation can be performed.

[0048] (First step) By operating the vibrating feeders 3-2 to 3-5 and the crushing mechanisms 2-1 to 2-3, as shown in Fig. 1 or Fig. 5, the powder 15 can be circulated and transported by the circulation path 16 including the transport paths 8-2 to 8-5.

[0049] (Second step) For the powder 15 being conveyed on the conveying paths 8-2 to 8-5, a film-forming material is supplied from the film-forming units 6-1 to 6-4 in a film-forming capable state, and a film is formed on the surface of the particles located at least on the surface layer of the powder 15. The film-forming method by the film-forming unit is preferably any one of metalorganic chemical vapor deposition, plasma-enhanced chemical vapor deposition, sputtering, ion plating, evaporation, ion beam, atomic beam, or a combination of two or more of these methods. The film-forming process at this time can be selected according to the film type to be formed, for example, DC-magnetron, DC-pulse magnetron, RF-magnetron. The film-forming chamber 4-2 is evacuated by the exhaust pump 7-1. As the process gas, for example, argon or a mixed gas of argon and oxygen or a mixed gas of argon and nitrogen is used.

[0050] (The third step) At least at one location in the circulation path 16, the aggregates of the powder 15 are crushed. In FIG. 1, the crushing is performed as follows. The powder formed by the film-forming unit 6-1 on the conveying path 8-2 falls from the end of the conveying path 8-2 onto the ultrasonic sieve of the crushing mechanism 2-1, is crushed, and is supplied to the conveying path 8-3. The powder on the conveying path 8-3 is formed under the same film-forming conditions as the film-forming unit 6-1 by the film-forming unit 6-2, falls from the end of the conveying path 8-3 onto the ultrasonic sieve of the crushing mechanism 2-2, is crushed, and is supplied to the conveying path 8-4. The powder on the conveying path 8-4 is formed under the same film-forming conditions as the film-forming unit 6-1 by the film-forming unit 6-3, falls from the end of the conveying path 8-4 onto the ultrasonic sieve of the crushing mechanism 2-3, is crushed, and is supplied to the conveying path 8-5. The powder on the conveying path 8-5 is formed under the same film-forming conditions as the film-forming unit 6-1 by the film-forming unit 6-4, falls from the end of the conveying path 8-5, and is supplied to the conveying path 8-2.

[0051] Here, the first step and the third step may be performed simultaneously. This is the case where the powder 15 is circulated and conveyed in the circulation path 16 without film formation. Furthermore, the first step, the second step, and the third step may be performed simultaneously. This is the case where the powder 15 is circulated and conveyed in the circulation path 16 while performing film formation and crushing.

[0052] It is preferable to perform the crushing treatment in the third step at least once while the thickness of the thin film formed in the second step is 20 nm or less. Preferably it is 5 nm or less, more preferably 2 nm or less. The lower limit of the thickness of the thin film is not particularly limited, but from the viewpoint of productivity, it is preferably 0.01 nm or more. As such an example, there is a form in which when forming a film again in the second step on the particles subjected to the crushing treatment in the third step, the crushing treatment in the third step is performed again while the thickness of the thin film is 20 nm or less. Aggregates of powder are expressed by liquid crosslinking, film crosslinking, etc. In the case of film crosslinking, if the thickness of the thin film exceeds 20 nm, the crushing efficiency decreases. Therefore, if the crushing treatment is performed before the thickness of the thin film reaches 20 nm, it is possible to uniformly form a film on the surface of each particle of the powder while suppressing the aggregation of the powder.

[0053] Until the film thickness reaches the target value, the powder is transported, crushed by an ultrasonic sieve as a crushing mechanism, and a film is formed by a film forming unit. At this time, during the circulation and transportation of the powder 15, film formation on the surface of each particle of the powder 15 and crushing of the aggregates of the powder 15 are repeatedly performed. When the film thickness reaches the target value, film formation is stopped.

[0054] In this embodiment, it is preferable that the number of repetitions of film formation / crushing is 2 times or more the estimated deposition number of the transported powder. A more uniform powder surface film formation can be achieved. Here, the estimated deposition number is a numerical value indicating how many layers of powder are overlapping on the transport path. Assuming the thickness of the powder is t (μm) and the number average particle diameter of the powder is P (μm), the estimated deposition number (pieces) is obtained by Equation 1. (Equation 1) Estimated deposition number (pieces) = t / P The thickness of the powder is obtained by Equation 2, assuming the input mass of the powder is W (g), the bulk density of the powder is d (g / cm 3 ), and the area of the transport path is S (cm 2 ). (Equation 2) t (μm) = W / (d · S) × 10 -4 For example, when the estimated number of particles is 200, the number of film formation / crushing repetitions is preferably 400 times or more. In the case of the apparatus of FIG. 1, film formation / crushing is performed three times while the powder circulates once through the circulation path 16. Therefore, in this example, it is preferable to continue film formation until the powder circulates through the circulation path 16 for 134 times or more.

[0055] (Post-process) As shown in FIG. 6, open the second opening / closing door 9-2 and move the trough 8-6 to the transport path 8-5. Drop the powder 15 into the trough 8-6. By operating the vibration feeder 3-6, the powder 15 dropped onto the trough 8-6 accumulates in the discharge hopper 1-3. By operating all of the vibration feeders 3-2 to 3-5, all of the powder 15 accumulates in the discharge hopper 1-3. At this time, the crushing mechanisms 2-1 to 2-3 may be operated. Next, as shown in FIG. 7, after all of the powder 15 has been accumulated in the discharge hopper 1-3, return the trough 8-6 to the preliminary chamber 4-1 and close the second opening / closing door 9-2. Next, as shown in FIG. 8, return the preliminary chamber 4-1 to atmospheric pressure, open the first opening / closing door 9-1, and move the discharge hopper 1-3 to the glove box 10. Take out the coated powder from the discharge hopper 1-3.

[0056] (Second aspect: form in which the circulation path has a regular helical surface and one stepped portion) The powder surface film forming apparatus 200 according to the present embodiment will be described with reference to FIGS. 10 to 11. This is an apparatus suitable for a simple type and small amount of film formation. The description will focus on the parts different from the first aspect, and the description of the common parts may be omitted. Similar to the first aspect, the film forming apparatus 200 of the present embodiment preferably includes, in addition to the film forming chamber 34, a glove box, a preliminary chamber, a first opening / closing door provided between the glove box and the preliminary chamber, a second opening / closing door provided between the preliminary chamber and the film forming chamber, a powder supply mechanism, and a powder discharge mechanism (all not shown). The preliminary chamber and the film forming chamber communicate with each other through an opening / closing door.

[0057] Inside the internal space of the film formation chamber 34, a powder transfer mechanism 3, a film formation unit 36, a disintegration mechanism 32, a relay mechanism 2, and a circulation path 16 are arranged. The film formation chamber 34 is evacuated by an exhaust pump 37 such as a rotary pump, an oil diffusion pump, or a turbo molecular pump.

[0058] The powder transfer mechanism 3 has a bowl-shaped trough and a vibration feeder 33 as a transfer path 38. A vibration feeder 33 is connected to the transfer path 38. Here, it is preferable to have a cooling mechanism for cooling the transfer path 38. Further, it is preferable to have a cooling mechanism for cooling the housing of the electromagnetic coil of the vibration feeder 33.

[0059] In FIGS. 10 to 11, the transfer path 38 has a constant spiral surface 38a, and a step portion 38d between the upper end portion 38b and the lower end portion 38c of the constant spiral surface due to spiral circulation. The powder transfer mechanism 3 transfers the powder 15 to the upper side of the spiral of the constant spiral surface by the operation of the vibration feeder 33. That is, the powder 15 is transferred so as to rise on the constant spiral surface 38a from the lower end portion 38c to the upper end portion 38b of the constant spiral surface, and is dropped from the upper end portion 38b to the lower end portion 38c. Here, the disintegration mechanism 32 is arranged at a position to receive the powder falling from the upper end portion 38b of the constant spiral surface, and the powder disintegrated by the disintegration mechanism 32 is supplied to the lower end portion 38c of the constant spiral surface. By having such an arrangement relationship in the powder surface film formation apparatus 200, the relay mechanism 2 sends the powder 15 from the upper end portion 38b of the transfer path to the disintegration mechanism 32, and returns the powder 15 after the disintegration process to the lower end portion 38c of the transfer path. Thus, in FIGS. 10 to 11, the relay mechanism 2 is installed at one place in the transfer path 38. FIGS. 10 to 11 show a form in which a guide 38e is installed at the upper end portion 38b of the constant spiral surface. The guide 38e can efficiently drop the powder 15 to the disintegration mechanism 32.

[0060] The relay mechanism 2 installed in the transfer path 38 and the step portion 38d constitutes one circulation path 16. With such a configuration, while the powder 15 is circulated and transferred in the circulation path 16, film formation on the surface of each particle of the powder 15 and disintegration of powder aggregates can be repeatedly performed.

[0061] The crushing mechanism 32 is the same as in the first aspect. Also, the film forming unit 36 is the same as in the first aspect. However, it is preferable that the entire constant helical surface 38a of the film forming unit 36 be the film forming region.

[0062] Next, a method for manufacturing coated powder using the powder surface film forming apparatus 200 will be described. The method for manufacturing coated powder is the same as in the first aspect. In the first step, the powder 15 is circulated and conveyed by a circulation path 16 including a conveyance path 38. In the second step, a film forming material is supplied in a film forming capable state from a film forming unit 36 that is disposed at a position facing the constant helical surface 38a and that has all or part, preferably the entire surface, of the constant helical surface as the film forming region, onto the powder 15 being conveyed on the conveyance path 38, so as to form a film on the surfaces of at least the particles located in the surface layer of the powder 15. In the third step, the agglomerates of the powder 15 are crushed by the crushing mechanism 32 of the relay mechanism 2 installed at the step portion 38d. During the circulation and conveyance of the powder 15, film formation on the surfaces of the respective particles of the powder 15 and crushing of the agglomerates of the powder 15 are repeatedly performed. In the method for manufacturing coated powder, similar to the first aspect, the previous step and the subsequent step may be carried out.

[0063] Also, coated powder may be manufactured according to the following procedure. (Raw material input) The raw material powder is subjected to a vacuum drying treatment. Thereafter, an appropriate amount of the powder is placed on the constant helical surface 38a in the atmosphere. The film forming chamber 34 is closed, and evacuation is slowly performed using the evacuation pump 37. (Powder conveyance) In advance, the conveyance speed of the vibration feeder 33 and the crushing output of the ultrasonic sieve as the crushing mechanism 32 are adjusted. It is preferable that the discharge speed from the ultrasonic sieve be faster than the conveyance speed. This can suppress the powder from staying on the ultrasonic sieve. The vibration feeder 33 and the crushing mechanism 32 are operated. After several seconds, the powder on the constant helical surface 38a automatically becomes of a uniform thickness and fills the constant helical surface 38a. The shape of the constant helical surface 38a may be inclined inward (toward the center of the helix). This can prevent the powder from being biased outward by centrifugal force. (Film formation) Introduce the process gas. When the film forming unit 36 is operated to start supplying the film forming material from the cathode in a film formable state, a thin film is formed on the powder surface on the constant spiral surface 38a facing the cathode. Subsequently, the powder is crushed by an ultrasonic sieve, and these operations are repeated. When the film thickness reaches the target value, the film formation of the film forming unit 36 stops. (Powder recovery) Introduce air or an inert gas into the film forming chamber 34 to return it to atmospheric pressure. The trough having the constant spiral surface 38a and the vibrating feeder 33 are collectively pulled out from the film forming chamber 34, and the coated powder is recovered. The extraction may be performed in a draft.

[0064] (Third aspect: The form in which the circulation path has a constant spiral surface and two or more stepped portions) The powder surface film forming apparatus 300 according to the present embodiment will be described with reference to FIGS. 12 to 17. The description will be centered on the parts different from the first aspect, and the common parts may be omitted. Similar to the first aspect, the film forming apparatus 300 of the present embodiment preferably includes, in addition to the film forming chamber 54-2, a glove box (not shown), a preliminary chamber 54-1, a first opening / closing door (not shown) provided between the glove box and the preliminary chamber, a second opening / closing door 59-2 provided between the preliminary chamber and the film forming chamber, a powder supply mechanism 61, and a powder discharge mechanism 62. The preliminary chamber 54-1 and the film forming chamber 54-2 communicate with each other via the second opening / closing door 59-2.

[0065] In the internal space of the film forming chamber 54-2, a powder transport mechanism 3, a film forming unit 56, a crushing mechanism 52, a relay mechanism 2, and a circulation path 16 are arranged. The film forming chamber 54-2 is evacuated by an exhaust pump 57 such as a rotary pump, an oil diffusion pump, or a turbo molecular pump.

[0066] As shown in FIG. 12, a powder supply mechanism 61 and a powder discharge mechanism 62 are arranged in the internal space of the preliminary chamber 54-1. As shown in FIG. 13, the powder supply mechanism 61 has a trough 58-1 for supplying raw material powder and a vibratory feeder 53-2. Also, as shown in FIG. 13, the powder discharge mechanism 62 has a trough 58-6 for discharging powder and a vibratory feeder 53-3. A eaves-shaped guide 58e2 may be provided at the upper end portion 58b2 of the constant spiral surface 58a2. A eaves-shaped guide 58e1 may be provided at the upper end portion 58b1 of the constant spiral surface 58a1.

[0067] The powder conveying mechanism 3 has a bowl-shaped trough as a conveying path 58 and a vibratory feeder 53-1. A vibratory feeder 53-1 is connected to the conveying path 58. Here, it is preferable to have a cooling mechanism for cooling the conveying path 58. Also, it is preferable to have a cooling mechanism for cooling the housing of the electromagnetic coil of the vibratory feeder 53-1.

[0068] In Fig. 12, the conveyance path 58 has n (where n ≥ 2) regular helical surfaces 58a1, 58a2 (n = 2 in Fig. 12) having the same central axis and arranged adjacent to each other, and n step portions 58d1, 58d2 between the upper end portions 58b1, 58b2 of the regular helical surfaces 58a1, 58a2 and the lower end portions 58c1, 58c2 of the adjacent regular helical surfaces. The powder conveyance mechanism 3 conveys the powder 15 to the upper side of the helix of the regular helical surface by the operation of the vibratory feeder 53-1. That is, the powder 15 is conveyed so as to ascend on the regular helical surface 58a1 from the lower end portion 58c2 to the upper end portion 58b1, and is dropped from the upper end portion 58b1 to the lower end portion 58c1. Also, the powder 15 is conveyed so as to ascend on the regular helical surface 58a2 from the lower end portion 58c1 to the upper end portion 58b2, and is dropped from the upper end portion 58b2 to the lower end portion 58c2. Here, the crushing mechanism 52 is arranged at a position to receive the powder falling from the upper end portion 58b1 of the regular helical surface 58a1, and the powder crushed by the crushing mechanism 52 is supplied to the lower end portion 58c1 of the regular helical surface 58a2. Since the powder surface film-forming device 300 has such an arrangement relationship, the relay mechanism 2 sends the powder 15 from the upper end portion 58b1 of the conveyance path to the crushing mechanism 52, and transfers the powder 15 after the crushing process to the lower end portion 58c1 of the conveyance path. Thus, in Fig. 12, the relay mechanism 2 is installed at one location in the conveyance path 58. Note that the relay mechanism is not arranged at the step portion 58d2.

[0069] The conveyance path 58 including the step portion 58d2 and the relay mechanism 2 installed at the step portion 58d1 constitute a single circulation path 16. With such a configuration, while the powder 15 is circulated and conveyed in the circulation path 16, film formation on the surface of each particle of the powder 15 and crushing of the powder agglomerates can be repeatedly performed.

[0070] The crushing mechanism 52 is the same as in the first aspect. Also, the film-forming unit 56 is the same as in the first aspect. However, it is preferable that the film-forming unit 56 uses the entire n regular helical surfaces 58a1, 58a2 arranged adjacent to each other as the film-forming region.

[0071] Next, a method for manufacturing coated powder using the powder surface film-forming apparatus 300 will be described. The method for manufacturing coated powder is the same as in the first aspect. In the first step, the powder 15 is circulated and conveyed by a circulation path 16 including a conveyance path 58. In the second step, for the powder 15 being conveyed on the conveyance path 58, a film-forming material is supplied in a film-formable state from a film-forming unit 56 disposed at a position facing the constant spiral surfaces 58a1 and 58a2, and at least the entire or part, preferably the entire surface of the constant spiral surface is defined as a film-forming region, to form a film on the surface of the particles located in at least the surface layer of the powder 15. In the third step, the agglomerates of the powder 15 are crushed by a crushing mechanism 52 of a relay mechanism 2 installed at a step portion 58d1. During the circulating conveyance of the powder 15, film formation on the surface of each particle of the powder 15 and crushing of the agglomerates of the powder 15 are repeated.

[0072] In the method for manufacturing coated powder, as in the first aspect, it is preferable to perform pre-steps and post-steps. As shown in FIGS. 14 and 15, powder is supplied using a powder supply mechanism 61. That is, when the second opening / closing door 59-2 is open, the trough 58-1 for supplying raw material powder supplies the powder before film formation to the constant spiral surface 58a1 by the operation of the vibratory feeder 53-2. As shown in FIGS. 16 and 17, powder is discharged using a powder discharge mechanism 62. That is, as shown in FIGS. 16 and 17, the trough 58-6 for powder discharge moves to a position where it receives the powder falling from the upper end portion 58b2 of the constant spiral surface 58a2 at the step portion 58d2 when the second opening / closing door 59-2 is open, and collects the powder. The powder on the trough 58-6 for powder discharge is collected in a discharge hopper (not shown) by operating the vibratory feeder 53-3. Thereafter, the second opening / closing door 59-2 is closed, and air or an inert gas is introduced into the preliminary chamber 54-1 to return to atmospheric pressure, and the coated powder having a predetermined film thickness is collected.

[0073] (Fourth Aspect: Form in which the circulation path includes bucket conveyance) The powder surface film forming apparatus 400 according to the present embodiment will be described with reference to FIG. 18. The description will focus on the parts different from the first aspect, and the common parts may be omitted. Similar to the first aspect, the film forming apparatus 400 of the present embodiment includes, in addition to the film forming chamber 74-2, a glove box (not shown), preliminary chambers 74-1a and 74-1b, a first opening and closing door (not shown) provided between the glove box and the preliminary chambers, second opening and closing doors 79-2a and 79-2b provided between the preliminary chambers and the film forming chamber, a powder supply mechanism 81, and a powder discharge mechanism 82. The preliminary chambers 74-1a and 74-1b communicate with the film forming chamber 74-2 via the second opening and closing doors 79-2a and 79-2b.

[0074] Inside the internal space of the film forming chamber 74-2, a powder transport mechanism 3, film forming units 76-1 and 76-2, crushing mechanisms 72-1 and 72-2, a relay mechanism 2, and a circulation path 16 are arranged. The film forming chamber 74-2 is evacuated by an exhaust pump 77-1 such as a rotary pump, an oil diffusion pump, or a turbo molecular pump. The preliminary chamber 74-1a is evacuated by an exhaust pump 77-2. The preliminary chamber 74-1b is evacuated by an exhaust pump 77-3.

[0075] As shown in Fig. 18, a powder supply mechanism 81 is disposed in the internal space of the preliminary chamber 74-1a, and a powder discharge mechanism 82 is disposed in the internal space of the preliminary chamber 74-1b. The powder supply mechanism 81 has a raw material input hopper 71-1. The raw material input hopper 71-1 supplies the powder before film formation to the powder supply hopper 71-2 when the second opening / closing door 79-2a is open. The powder supply hopper 71-2 is disposed above the starting point of the most upstream of the plurality of transfer paths 78-1 and 78-2 disposed in the film formation chamber 74-2. Further, the powder discharge mechanism 82 has a powder recovery hopper 71-4. The powder recovery hopper 71-4 recovers the powder after film formation from the powder discharge hopper 71-3 when the second opening / closing door 79-2b is open. The powder discharge hopper 71-3 is disposed below the end point of the most downstream of the plurality of transfer paths 78-1 and 78-2. Below the powder discharge hopper 71-3, the respective buckets conveyed by the powder return mechanism 80 are arranged in a circulating manner.

[0076] The powder transfer mechanism 3 includes a powder supply hopper 71-2, elongated troughs 78-1 and 78-2 having a U-shaped cross section as transfer paths, vibration feeders 73-1 and 73-2, a powder discharge hopper 71-3, and a powder return mechanism 80. The vibration feeders 73-1 and 73-2 are connected to the transfer paths 78-1 and 78-2. Here, it is preferable to have a cooling mechanism for cooling the transfer paths 78-1 and 78-2. Further, it is preferable to have a cooling mechanism for cooling the housings of the electromagnetic coils of the vibration feeders 73-1 and 73-2.

[0077] In FIG. 18, the powder conveying mechanism 3 arranges a plurality of conveying paths 78-1 and 78-2 along the upstream side to the downstream side in the conveying direction of the powder 15, and has a relationship in which the starting point in the conveying direction of the adjacent conveying path 78-2 is arranged below the end point in the conveying direction of the conveying path 78-1. The conveying paths 78-1 and 78-2 are arranged, for example, with a downward inclination of 5 to 15 degrees. By providing the inclination, the influence of gravity is also added, the conveying speed of the powder is improved, and even if powder with poor transportability is mixed in, the transport efficiency can be increased. The powder conveying mechanism 3 conveys the powder 15 downward along the inclination of the conveying path 78-1 by the operation of the vibration feeder 73-1. Here, the relay mechanism 2 arranges the crushing mechanism 72-2 at a position to receive the powder 15 falling from the end point in the conveying direction of the conveying path 78-1, and supplies the powder crushed by the crushing mechanism 72-2 to the starting point in the conveying direction of the adjacent conveying path 78-2. Since the powder surface film forming device 400 has such an arrangement relationship, the relay mechanism 2 sends the powder 15 from the conveying path 78-1 to the crushing mechanism 2 and transfers the powder 15 after the crushing process to the conveying path 78-2. When three or more conveying paths are arranged, it is preferable that the relay mechanism 2 is installed at at least one location between the plurality of conveying paths. In the present embodiment, it is preferable to further have a crushing mechanism 72-1 at the bottom of the powder supply hopper 71-2. The powder supplied to the starting point in the conveying direction of the conveying path 78-1 can be provided in a crushed state. The powder is dropped from the end point in the conveying direction of the conveying path 78-2 to the powder discharge hopper 71-3. The powder surface film forming device 400 has a powder return mechanism 80. The powder return mechanism has each bucket to be conveyed, and each bucket is arranged to circulate below the powder discharge hopper 71-3 and above the powder supply hopper 71-2, receives the powder dropped from the powder discharge hopper 71-3, and sends the received powder to the powder supply hopper 71-2.

[0078] The powder supply hopper 71-2, the conveying paths 78-1 and 78-2, the relay mechanism 2, the powder discharge hopper 71-3, and the powder return mechanism 80 constitute a single circulation path 16. With such a configuration, while the powder 15 is circulated and conveyed in the circulation path 16, film formation on the surface of each particle of the powder 15 and crushing of the powder agglomerates can be repeatedly performed.

[0079] The crushing mechanisms 72-1 and 72-2 are the same as in the first embodiment. Also, the film-forming units 76-1 and 76-2 are the same as in the first embodiment. Above the transport path 78-1, a laser displacement meter 84 is installed. The laser displacement meter 84 measures the thickness of the powder being transported on the transport path 78-1. The control mechanism of the powder surface film-forming apparatus 400 obtains the value of the laser displacement meter 84, and adjusts the feed rate of the powder return mechanism 80, the supply amount of the powder supply hopper 71-2, and the transport rates of the vibratory feeders 73-1 and 73-2 so that the powder thickness is the desired thickness and the change over time is small and the displacement is small.

[0080] Next, a method for manufacturing coated powder using the powder surface film-forming apparatus 400 will be described. The method for manufacturing coated powder is also the same as in the first embodiment. In the first step, the powder 15 is circulated and transported by a circulation path 16 including the transport paths 78-1 and 78-2. In the second step, for the powder 15 being transported on the transport paths 78-1 and 78-2, a film-forming material is supplied in a film-formable state from the film-forming units 76-1 and 76-2 disposed at positions facing the transport paths 78-1 and 78-2 and having all or part of the transport path as a film-forming region, and a film is formed on the surfaces of at least the particles located in the surface layer of the powder 15. In the third step, the aggregate of the powder 15 is crushed by the crushing mechanisms 72-1 and 72-2 of the relay mechanism 2. During the circulation and transport of the powder 15, film formation on the surfaces of the respective particles of the powder 15 and crushing of the aggregate of the powder 15 are repeatedly performed. In the method for manufacturing coated powder, it is preferable to perform the previous step and the subsequent step in the same manner as in the first embodiment.

[0081] Also, coated powder may be manufactured according to the following procedure. (Raw material input) The film formation chamber 74-2 is evacuated by an exhaust pump 77-1. A rotary pump, an oil diffusion pump, a turbo molecular pump, or a cryopump may be used. After raw material powder is charged into the raw material charging hopper 71-1, the evacuation of the preliminary chamber 74-1a is performed by an exhaust pump 77-2. A rotary pump is used as the exhaust pump 77-2. The preliminary chamber 74-1a may be equipped with a heater or a reverse sputtering mechanism. Moisture on the powder surface is removed by vacuum or heat treatment, or reverse sputtering. When the pressure in the preliminary chamber 74-1a becomes lower than 10 -1 Pa, the evacuation by the exhaust pump 77-2 stops, and the preliminary chamber 74-1a is evacuated by the exhaust pump 77-1 via the path 77-2R. When the degrees of vacuum in the preliminary chamber 74-1a and the film formation chamber 74-2 become approximately the same, the second opening / closing door 79-2a is opened. The raw material charging hopper 71-1 is moved close to the raw material supply hopper 71-2, and the opening of the raw material charging hopper 71-1 is opened inside the raw material supply hopper 71-2. The raw material is loaded into the raw material supply hopper 71-2. At this time, the bucket installed in the powder return mechanism 80 is placed at a position where it does not interfere when the raw material powder moves from the raw material charging hopper 71-1 to the raw material supply hopper 71-2. After the raw material charging hopper 71-1 is returned to its original position, the second opening / closing door 79-2a is closed. Then, the path 77-2R is adjusted to switch to the evacuation of only the film formation chamber 74-2. (Powder transfer) The vibration feeders 73-1 and 73-2 and the ultrasonic sieves as the crushing mechanisms 72-1 and 72-2 are operated. The powder crushed by the crushing mechanism 72-1 is supplied onto the conveyance path 78-1 and conveyed by the vibration feeder 73-1. The powder is crushed again by the crushing mechanism 72-2 and then conveyed on the conveyance path 78-2. Thereafter, it accumulates in the powder discharge hopper 71-3. The powder discharge hopper 71-3 is equipped with a load cell (not shown). When powder of an arbitrary weight accumulates in the discharge hopper 71-3, the powder discharge hopper 71-3 opens, and the powder is discharged into a bucket arranged at the lower part of the hopper. Thereafter, the powder discharge hopper 71-3 closes, and the bucket is conveyed to return the discharged powder to the raw material supply hopper 71-2. The thickness of the powder is measured by the laser displacement meter 84, and the conveyance amount of the powder is measured by the load cell equipped in the powder discharge hopper 71-3. These results are fed back to the crushing mechanisms 72-1 and 72-2, the vibration feeders 73-1 and 73-2, and arbitrary conveyance conditions are determined. Further, in order to stably convey and form a film without the powder in the raw material supply hopper 71-2 running out during conveyance, the timing of powder discharge of the load cell, the conveyance speed of the bucket, and the charging amount of the raw material are adjusted. When the conveyance conditions are determined, powder conveyance is continuously performed. (Film formation) Process gas is introduced. Although it can be arbitrarily selected according to the film formation method, in the case of sputtering, argon, a mixed gas of argon and oxygen, or a mixed gas of argon and nitrogen is preferable. The film formation process at this time can be properly selected according to the film type to be formed, such as DC-magnetron, DC pulse-magnetron, or RF-magnetron. When the film formation units 76-1 and 76-2 are operated to start supplying the film forming material from the cathode in a film formable state, a thin film is formed on the powder surface on the conveyance paths 78-1 and 78-2 facing the cathode. Subsequently, it is crushed by an ultrasonic sieve, and these operations are repeated. When the film thickness reaches the target value, the film formation of the film formation units 76-1 and 76-2 stops. (Powder recovery) When film formation is completed, all the coated powder is collected in the powder discharge hopper 71-3. At this time, the buckets installed in the powder return mechanism 80 are placed at positions where they do not interfere when the coated powder moves from the powder discharge hopper 71-3 to the powder recovery hopper 71-4. In advance, the preliminary chamber 74-1b is evacuated by the exhaust pump 77-3, and vacuum pumping is performed by the exhaust pump 77-1 via the path 77-3R. When the degree of vacuum in the preliminary chamber 74-1b and the film formation chamber 74-2 becomes approximately the same, the second opening / closing door 79-2b is opened. The powder recovery hopper 71-4 is moved to the vicinity of the discharge hopper 71-3, and the mouth of the discharge hopper 71-3 is opened. The coated powder is loaded into the powder recovery hopper 71-4. After returning the powder recovery hopper 71-4 to its original position, the second opening / closing door 79-2b is closed. Then, the path 77-3R is adjusted, and vacuum exhaust is switched to only the film formation chamber 74-2. The preliminary chamber 74-1b is returned to atmospheric pressure by introducing air or an inert gas, and the coated powder with a predetermined film thickness is recovered.

Example

[0082] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not construed as being limited to the examples.

[0083] (Example 1) Using the powder surface film forming apparatus shown in FIG. 1, powder having an Ag thin film formed on the surface of Cu powder is produced. First, four Ag targets (purity 99.9%, target surface is 150×100 mm) are prepared and attached to the film forming units 6-1 to 6-4 respectively. All the sputtering power supplies are DC power supplies, and the DC-magnetron process is selected. Next, 1 kg of Cu powder with an average particle size of 5 μm is put into the ultrasonic sieve hopper 1-1 arranged in the preliminary chamber 4-1, and the preliminary chamber is evacuated to 5×10 -3 Pa or less by the rotary pump installed as the exhaust pump 7-2. After that, moisture removal is performed at 200°C for 2 hours using the heater equipped in the hopper. The film formation chamber 4-2 is evacuated to 5×10, which is the same as that of the preliminary chamber 4-1 -3After evacuating to below Pa, open the second opening / closing door 9-2 and move the powder supply mechanism 11 toward the transport path 8-2. Then, while crushing the Cu powder with the ultrasonic sieve 1-1a, supply it onto the trough 8-1 of the powder supply mechanism 11, operate the vibrating feeder 3-1, and transport the powder at a transport speed of 50 mm / s. The powder transported by the vibrating feeder 3-1 is supplied from the end of the trough 8-1 to the transport path 8-2 and then transported to the transport path 8-3 by the vibrating feeder 3-2. At this time, the vibrating feeder 3-2 transported the powder at a transport speed of 130 mm / s. When supplying the powder from the transport path 8-2 to the transport path 8-3, the powder falls onto the crushing mechanism 2-1 having an ultrasonic sieve installed between the transport paths, and the crushing process is performed. The same process is performed in the transport paths 8-3, 8-4, 8-5, and the crushing mechanisms 2-2, 2-3. The vibrating feeders 3-3 to 3-5 transported the powder at a transport speed of 130 mm / s, the same as the vibrating feeder 3-2, and formed a powder circulation path 16. The crushing mechanisms 2-1 to 2-3 had previously confirmed the vibration acceleration in the atmosphere. After adjusting the output, the vibration acceleration was 30 to 100 m / s 2 was set. After supplying all the Cu powder on the trough 8-1 to the circulation path 16, return the powder supply mechanism 11 to the preliminary chamber and close the second opening / closing door 9-2. Then, operate the turbo molecular pump (TMP) installed as the exhaust pump 7-1 inside the vacuum chamber 4-2 and evacuate to below 5×10 -5 Pa. After that, flow argon gas and adjust to maintain a pressure of 0.5 Pa. With the circulation path 16 formed, apply 300 W (film formation power density 2.0 W / cm 2)'s output was multiplied and sputtering was performed. Under the current film formation conditions and powder conveyance speed, it is calculated that a film with a thickness of 2 nm is deposited on the powder surface when the powder passes through a certain film formation unit. Since the film thickness is small, the powder aggregates are sufficiently crushed and transported to the adjacent film formation unit. The powder is repeatedly transported, crushed by an ultrasonic sieve, and film-formed until the Ag film thickness reaches 10 nm, and then the film formation is stopped. After the film formation is stopped, the vibration feeders 3-2 to 3-5 are stopped, the powder conveyance is stopped, the pressures in the preliminary chamber 4-1 and the film formation chamber 4-2 are made equal, the second opening / closing door 9-2 is opened, and the powder discharge mechanism 12 is moved to the conveyance path 8-5 side. The trough 8-6 of the powder discharge mechanism 12 is moved below the conveyance path 8-5, and the vibration feeder 3-6 is operated at a conveyance speed of 130 mm / s. The vibration feeders 3-2 to 3-5 are restarted, and the powder on the conveyance paths 8-2 to 8-5 is dropped into the trough 8-6. The powder is all collected into the discharge hopper 1-3 through the trough 8-6.

[0084] (Example 2) The Cu powder with an average particle size of 5 μm was changed to LiCoO2 powder (LCO powder) with an average particle size of 5 μm, the Ag target was changed to a LiNbO3 (LNO) target, the DC-magnetron process was changed to the RF-magnetron process, the 10-nm-thick Ag film was changed to a 5-nm-thick LNO film, the film formation argon gas pressure (0.5 Pa), output 300 W (film formation power density 2.0 W / cm 2 ) conditions were changed to a film formation argon gas pressure (1 Pa), output 200 W (film formation power density 1.3 W / cm 2 )), and the conditions for film formation until the Ag film thickness reaches 10 nm were changed to the conditions for film formation until the LNO film thickness reaches 5 nm. Coated powder was produced in the same manner as in Example 1 except for this.

[0085] (Example 3) Using the disk feeder type powder surface film forming apparatus shown in FIGS. 12 to 17, a powder with an Ag thin film formed on the surface of Cu powder is produced. First, an Ag target (purity 99.9%, target surface 150×45 mm) is attached to the film forming unit 56. The sputtering power supply is a high frequency power supply (frequency 13.56 MHz), and the RF-magnetron process is selected. Next, 32 g (≈8 cc) of Cu powder with an average particle size of 5 μm that has been previously dehumidified in a vacuum drying furnace is loaded into the transport trough 58-1 of the powder supply mechanism 61, and the preliminary chamber 54-1 is evacuated. After evacuating the film forming chamber 54-2 to the same vacuum as the preliminary chamber 54-1, the second opening / closing door 59-2 is opened, and the powder supply mechanism 61 is moved to the transport path 58 side. After moving the powder supply mechanism 61, the vibration feeder 53-1 is operated to move the powder on the trough 58-1 of the powder supply mechanism 61 to the transport path 58. After moving the powder onto the transport path 58, the vibration feeder 53-2 and the pulverizing mechanism 52 are operated, and the output of the vibration feeder 53-2 is set so that the time for the powder to travel one round on the transport path 58 is 4 seconds or less. After closing the second opening / closing door 59-2, the film forming chamber 54-2 is evacuated to a vacuum of 5×10 -3 Pa or less, argon gas is flowed, and the pressure inside the film forming chamber 54-2 is adjusted to maintain a pressure of 0.5 Pa. An output of 100 W (film forming power density 1.5 W / cm 2 ) is applied to the Ag target, and sputtering is performed. Until the film thickness of Ag reaches 20 nm, the powder is repeatedly transported, pulverized, and film formed, and then the film formation is stopped. After the film formation is stopped, the vibration feeder 53-2 is stopped, the powder transport is stopped, the pressures of the preliminary chamber 54-1 and the film forming chamber 54-2 are made equal, the second opening / closing door 59-2 is opened, and the powder discharge mechanism 62 is moved to the transport path 58 side. The trough 58-6 of the powder discharge mechanism 62 is moved to the transport path 58, and the vibration feeder 53-3 is operated. Also, the vibration feeder 53-2 is restarted to drop the powder on the transport path 58 into the trough 58-6 of the powder discharge mechanism 62. The powder is all recovered into the powder recovery hopper by the vibration feeder 53-3 through the trough 58-6.

[0086] (Comparative Example 1) A coated powder was produced in the same manner as in Example 3 except that the pulverizing mechanism was removed.

[0087] (Comparative Example 2) Using the barrel-type powder coating apparatus presented in JP-A-2020-186473, an Ag thin film was formed on the surface of Cu powder. One Ag target (purity 99.9%, target surface 150×35 mm) was prepared and attached to the cathode. The sputtering power supply 1 was a high-frequency power supply (frequency 13.56 MHz), and the RF-magnetron process was selected. Next, Cu powder with an average particle size of 5 μm that had been previously dehydrated in a vacuum drying furnace was loaded into the barrel container, and evacuation was performed until 1.3×10 -3 Pa. After that, argon gas was flowed and adjusted to maintain a pressure of 0.5 Pa. Then, an output was applied to the Ag target, the barrel container was rotated, and while the leveling part (round bar type) was shaken, film formation was performed until the film thickness of Ag reached 30 nm on the surface of the Cu powder.

[0088] (Film thickness after film formation) The film thicknesses of the powders formed in Examples 1 to 3, Comparative Example 1, and Comparative Example 2 were calculated from the analytical values of ICP and the specific surface area obtained by BET.

[0089] (Appearance of the powder after film formation) In Examples 1 to 3, there were no significant aggregates. In Examples 1 and 2, the color slightly changed to white, and in Example 3, the color further changed to white. In Comparative Example 1, there were many whiteish aggregates of 2 to 30 mm, and when the aggregates were broken, red powder was confirmed inside. In Comparative Example 2, there were no significant aggregates, and the color changed to white, but a large amount of powder adhered to the barrel wall surface, and red powder was confirmed from the back side where the adhesion was peeled off.

[0090] (Comparison of non-uniform adhesion 1) Using a JEOL JSM-IT800 Schottky field emission scanning electron microscope, the uneven adhesion of the powder of Example 3 and the powder not adhered to the barrel wall surface of Comparative Example 2 was confirmed. In the BD mode with the detector UED, it was set to the filter -50V and observed with the composition emphasized. The observation magnification was 1000 times that of a field of view where 100 or more powder particles were present. In the secondary electron image, Ag is observed as white and Cu is observed as darker than Ag due to the difference in atomic weight. The uneven adhesion was evaluated based on this difference in color tone. In Example 3, there was almost no contrast in color tone, and it was found that each grain of Cu powder was almost covered with an Ag film. On the other hand, in Comparative Example 2, a strong contrast between white and black appeared, and it was found that each grain of Cu powder was not partially covered with an Ag film.

[0091] (Comparison of Adhesion Unevenness 2) Cross-sectional observation was performed on the powder of Example 3 and the powder not adhered to the barrel wall surface of Comparative Example 2 to confirm the adhesion unevenness and the uniformity of the film. For the observation, a JEOL JSM-IT800 Schottky field emission scanning electron microscope was used, and the observation magnifications were 1000 times and 5000 times. To obtain the observation cross-section of the powder, the powder was embedded in a cured resin, the resin was mechanically polished, and the powder cross-section was prepared by ion milling. In the cross-section of the powder of Example 3, when observed at a magnification of 1000 times, more than 100 Cu cross-sections could be confirmed, and it was confirmed that a faint white Ag film was attached to the surface of each grain. From the scale bar of the observation image, the film thickness of the Ag film was about 100 nm. There were some grains with a thicker Ag film. When the powder cross-section of Example 3 was observed at a magnification of 5000 times, it was confirmed that an Ag film with an approximately uniform film thickness covered each grain of Cu powder. In the cross-section of the powder of Comparative Example 2, when observed at a magnification of 1000 times, more than 100 Cu cross-sections could be confirmed, but there were grains with a very thick Ag film. The thickness of the Ag film of this grain was about 1000 - 5000 nm from the scale bar of the observation image. When the powder cross-section of Comparative Example 2 was observed at a magnification of 5000 times, the presence of Cu powder with a non-uniform Ag film thickness and Cu powder without any Ag film was confirmed.

[0092] In view of the evaluation of the appearance of the powder after film formation, comparison of coating unevenness 1, and comparison of coating unevenness 2, in the powder surface film forming apparatus of the present disclosure, an excellent effect of uniform film formation was confirmed by a mechanism incorporating disintegration of aggregates.

Industrial Applicability

[0093] The powder surface film forming apparatus of the present invention can be used for many materials as a coating technology for various fine particles, such as coating of all-solid positive electrodes and negative electrodes, coating of metal paste powders, coating of catalysts, and magnetic core materials with oxide coating on iron powder.

Explanation of Signs

[0094] 100, 200, 300, 400 Powder surface film forming apparatus 1-1 Ultrasonic sieve hopper 1-1a Ultrasonic sieve 1-3 Discharge hopper 2 Relay mechanism 2-1~2-3, 32, 52, 72-1, 72-2 Disintegration mechanism 3 Powder conveying mechanism 3-1~3-6, 33, 53-1~53-3, 73-1, 73-2 Vibrating feeder 4-1, 54-1, 74-1a, 74-1b Preliminary chamber 4-2, 34, 54-2, 74-2 Film forming chamber 6-1~6-4, 36, 56, 76-1, 76-2 Film forming unit 7-1, 7-2, 37, 57, 77-1~77-3 Exhaust pump 8-1, 8-6, 58-1, 58-6 Trough 8-2~8-5, 38, 58, 78-1, 78-2 Conveying path 9-1 First opening / closing door 9-2, 59-2, 79-2a, 79-2b Second opening / closing door 10 Glove box 11, 61, 62 Powder supply mechanism 12 Powder discharge mechanism 15 Powder 16 Circulation path Regular helicoid 38a, 58a1, 58a2 Upper end of regular helicoid 38b, 58b1, 58b2 Lower end of regular helicoid 38c, 58c1, 58c2 Step portion 38d, 58d1, 58d2 Guide 38e, 58e1 Raw material input hopper 71-1 Powder supply hopper 71-2 Powder discharge hopper 71-3 Powder recovery hopper 71-4 Path 77-2R, 77-3R Powder return mechanism 80 Powder supply mechanism 81 Powder discharge mechanism 82 Laser displacement meter 84 Direction T of powder passing through mesh Direction V perpendicular to the direction of powder passing through mesh Direction P parallel to the direction of powder passing through mesh

Claims

1. An apparatus for forming a film on the surface of each particle of a powder, comprising: a powder conveying mechanism having at least one conveying path for the powder; a film forming unit disposed at a position facing at least one road surface of the conveying path and having all or part of the road surface as a film forming region; a crushing mechanism for crushing aggregates of the powder; a relay mechanism for sending the powder from at least one of the conveying paths to the crushing mechanism and returning the powder after the crushing process to the conveying path or transferring it to another conveying path; the powder conveying mechanism having a vibrating feeder; the conveying path and the relay mechanism constituting a single circulation path; a powder surface film forming apparatus, characterized in that during the circulating conveyance of the powder in the circulation path, film formation on the surface of each particle of the powder and crushing of aggregates of the powder are repeatedly performed.

2. An apparatus for forming a film on the surface of each particle of a powder, comprising: a powder conveying mechanism having at least one conveying path for the powder; a film forming unit disposed at a position facing at least one road surface of the conveying path and having all or part of the road surface as a film forming region; a crushing mechanism for crushing aggregates of the powder; a relay mechanism for sending the powder from at least one of the conveying paths to the crushing mechanism and returning the powder after the crushing process to the conveying path or transferring it to another conveying path; a film forming chamber; at least one preliminary chamber communicating with the film forming chamber via an opening / closing door; a powder supply mechanism; a powder discharge mechanism; the conveying path and the relay mechanism constituting a single circulation path; the powder conveying mechanism, the film forming unit, the crushing mechanism, the relay mechanism and the circulation path being disposed in the internal space of the film forming chamber; the powder supply mechanism and the powder discharge mechanism being disposed in the internal space of the preliminary chamber; a powder surface film forming apparatus, characterized in that during the circulating conveyance of the powder in the circulation path, film formation on the surface of each particle of the powder and crushing of aggregates of the powder are repeatedly performed.

3. An apparatus for forming a film on the surface of each particle of a powder, comprising: a powder conveying mechanism having at least one conveying path for the powder; a film forming unit disposed at a position facing at least one road surface of the conveying path and having all or part of the road surface as a film forming region; a crushing mechanism for crushing aggregates of the powder; A relay mechanism that sends the powder from at least one of the conveying paths to the crushing mechanism and returns the crushed powder to the conveying path or transfers it to another conveying path. The conveying path and the relay mechanism constitute a single circulation path. The powder conveying mechanism arranges a plurality of conveying paths annularly along the conveying direction of the powder, and in all of the plurality of conveying paths, the starting point of the conveying direction of the adjacent conveying path is arranged below the end point of the conveying direction of the conveying path. The relay mechanism arranges the crushing mechanism at a position to receive the powder falling from the end point of the conveying direction of the conveying path, and supplies the powder crushed by the crushing mechanism to the starting point of the conveying direction of the adjacent conveying path. The relay mechanism is installed at least at one location between the plurality of conveying paths. A powder surface film-forming device characterized by repeatedly performing film formation on the surface of each particle of the powder and crushing of the powder aggregates while circulating and conveying the powder in the circulation path.

4. An apparatus for forming a film on the surface of each particle of powder, A powder conveying mechanism having at least one conveying path for the powder, A film-forming unit arranged at a position facing at least one road surface of the conveying path, and having all or a part of the road surface as a film-forming region, A crushing mechanism for crushing the aggregates of the powder, A relay mechanism that sends the powder from at least one of the conveying paths to the crushing mechanism and returns the crushed powder to the conveying path or transfers it to another conveying path. The conveying path and the relay mechanism constitute a single circulation path. The conveying path has a normal helical surface and a stepped portion between the upper end and the lower end of the normal helical surface due to helical circulation. The film-forming unit has the entire normal helical surface as a film-forming region. The powder conveying mechanism conveys the powder to the upper side of the helix of the normal helical surface. The relay mechanism arranges the crushing mechanism at a position to receive the powder falling from the upper end of the normal helical surface, and supplies the powder crushed by the crushing mechanism to the lower end of the normal helical surface. A powder surface film-forming device characterized by repeatedly performing film formation on the surface of each particle of the powder and crushing of the powder aggregates while circulating and conveying the powder in the circulation path.

5. An apparatus for forming a film on the surface of each particle of powder, A powder conveying mechanism having at least one conveying path for the powder, A film forming unit that is disposed at a position facing at least one road surface of the transport path and that defines all or part of the road surface as a film forming region; A crushing mechanism for crushing the powder aggregates; A relay mechanism that sends the powder from at least one of the transport paths to the crushing mechanism and returns the crushed powder to the transport path or transfers it to another transport path; The transport path and the relay mechanism constitute a single circulation path; The powder transport mechanism has a relationship in which a plurality of transport paths are arranged along the upstream side to the downstream side in the transport direction of the powder, and the starting point in the transport direction of an adjacent transport path is arranged below the end point in the transport direction of the transport path; The relay mechanism arranges the crushing mechanism at a position for receiving the powder falling from the end point in the transport direction of the transport path and supplies the powder crushed by the crushing mechanism to the starting point in the transport direction of the adjacent transport path; The relay mechanism is installed at at least one location between the plurality of transport paths; A powder supply hopper disposed above the starting point of the most upstream one of the plurality of transport paths, a powder discharge hopper disposed below the end point of the most downstream one of the plurality of transport paths, and a powder return mechanism that sends the powder discharged from the powder discharge hopper to the powder supply hopper; A powder surface film forming apparatus characterized in that while the powder is circulated and transported in the circulation path, film formation on the surface of each particle of the powder and crushing of the powder aggregates are repeatedly performed. **Claim 6**: An apparatus for forming a film on the surface of each particle of powder, comprising: A powder transport mechanism having at least one transport path for the powder; A film forming unit that is disposed at a position facing at least one road surface of the transport path and that defines all or part of the road surface as a film forming region; A crushing mechanism for crushing the powder aggregates; A relay mechanism that sends the powder from at least one of the transport paths to the crushing mechanism and returns the crushed powder to the transport path or transfers it to another transport path; The transport path and the relay mechanism constitute a single circulation path; The crushing mechanism is a mechanical crushing mechanism; The mechanical crushing mechanism has a sieve for sieving the powder; The vibration of the sieve has a vibration component perpendicular to the mesh passing direction of the powder, or has a vibration component perpendicular to the mesh passing direction of the powder and a parallel vibration component; The acceleration of the vibration of the sieve is 10 m / s2 or more. A powder surface film-forming apparatus, characterized in that while the powder is circulated and conveyed in the circulation path, film formation on the surface of each particle of the powder and disintegration of aggregates of the powder are repeatedly performed. **Claim 7**: An apparatus for forming a film on the surface of each particle of a powder, comprising: a powder conveying mechanism having at least one conveying path for the powder; a film-forming unit disposed at a position facing at least one road surface of the conveying path, and having all or a part of the road surface as a film-forming region; a disintegration mechanism for disintegrating aggregates of the powder; a relay mechanism for sending the powder from at least one of the conveying paths to the disintegration mechanism, and returning the powder after the disintegration process to the conveying path or transferring it to another conveying path; wherein the conveying path and the relay mechanism constitute a single circulation path; a film-forming chamber, at least one preliminary chamber communicating with the film-forming chamber via an opening / closing door, a powder supply mechanism, and a powder discharge mechanism; wherein the powder conveying mechanism, the film-forming unit, the disintegration mechanism, the relay mechanism, and the circulation path are disposed in the internal space of the film-forming chamber; wherein the conveying path has n (where n ≧ 2) constant helical surfaces having the same central axis and arranged adjacent to each other, and n step portions between the upper end portions of the constant helical surfaces and the lower end portions of the adjacent constant helical surfaces; wherein the film-forming unit has the entire n constant helical surfaces arranged adjacent to each other as a film-forming region; wherein the powder conveying mechanism conveys the powder to the upper side of the helix of the constant helical surface; wherein the relay mechanism disposes the disintegration mechanism at a position for receiving the powder falling from the upper end portion of the constant helical surface at at least one of the step portions, and supplies the powder disintegrated by the disintegration mechanism to the lower end portion of the constant helical surface; wherein the powder supply mechanism is disposed in the internal space of the preliminary chamber, and supplies the powder before film formation to the constant helical surface at at least one of the step portions when the opening / closing door is open; wherein the powder discharge mechanism is disposed in the internal space of the preliminary chamber, and moves to a position for receiving the powder falling from the upper end portion of the constant helical surface at at least one of the step portions when the opening / closing door is open, and recovers the powder; A powder surface film-forming apparatus, characterized in that while the powder is circulated and conveyed in the circulation path, film formation on the surface of each particle of the powder and disintegration of aggregates of the powder are repeatedly performed. Claim 8. The powder surface film forming apparatus according to any one of claims 1 to 7, wherein the film forming unit is a film forming apparatus by any one of metalorganic chemical vapor deposition, plasma enhanced chemical vapor deposition, sputtering, ion plating, vapor deposition, ion beam, and atomic beam, or a combination of two or more of these.

9. A method for producing a coated powder in which a thin film is coated on the surface of each particle of the powder, a first step of circulating and transporting the powder through a circulation path including a transport path, a second step of supplying a film forming material in a film formable state from a film forming unit disposed at a position facing the road surface of the transport path and having all or part of the road surface as a film forming region to the powder being transported on the transport path, and forming a film on the surface of at least the particles located in the surface layer of the powder, a third step of crushing agglomerates of the powder at at least one location in the circulation path, wherein the transport path has a vibrating feeder, and the powder is transported by the operation of the vibrating feeder, A method for producing a coated powder, characterized in that during the circulating transportation of the powder, film formation on the surface of each particle of the powder and crushing of the agglomerates of the powder are repeatedly performed.

10. The method for producing a coated powder according to claim 9, wherein the crushing treatment in the third step is performed at least once while the thickness of the thin film formed in the second step is 20 nm or less.

11. The film forming method by the film forming unit is any one of metalorganic chemical vapor deposition, plasma enhanced chemical vapor deposition, sputtering, ion plating, vapor deposition, ion beam, and atomic beam, or a combination of two or more of these methods. The method for producing a coated powder according to claim 9.

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