JP7680285B2 - Powder film forming apparatus and powder film forming method - Google Patents

Description

This disclosure relates to a powder coating apparatus and a powder coating method for applying a coating process to the surface of powder.

As a technique for forming a film on the surface of a powder, for example, Patent Document 1 discloses a method for coating a fine powder by sputtering. This method involves subjecting a fine powder of metal, ceramic, or plastic to reduced pressure heat treatment in an inert atmosphere, placing the heat-treated fine powder in a rotating container containing a sputtering source and rotating the container to form a fluidized layer of the fine powder, and forming a coating on the fluidized fine powder by sputtering while the container is rotating.

Japanese Unexamined Patent Publication No. 2-153068

Incidentally, in order to efficiently form a film on the surface of the powder, it is necessary to thoroughly agitate the powder in the container used for the film formation process. However, with the technology disclosed in Patent Document 1, it cannot necessarily be said that the powder is thoroughly agitated in the container. Specifically, the technology in Patent Document 1 agitates the powder by rotating a rotating container with the fine powder placed at the bottom of the container, so the fine powder (powder) only moves along the bottom surface of the rotating container and the vicinity of the side surface connected to the bottom surface. Such powder movement alone may result in insufficient agitation of the powder.

This disclosure has been made in light of the above problems, and aims to provide a powder film-forming device and a powder film-forming method that can efficiently form a film on the surface of a powder by efficiently stirring the powder in a container for performing a film-forming process on the surface of the powder.

The powder film forming apparatus according to one aspect of the present disclosure is an apparatus for performing a film forming process on the surface of a powder, and is an apparatus body including a container having a bottom surface on which powder can be placed, in which a powder drop space is formed as a space continuing upward from the bottom surface within the container, an upper transport path is formed for transporting the powder placed on the bottom surface of the container upward in an area other than the powder drop space within the container, and the apparatus body is configured to be able to drop the powder transported upward along the upper transport path through the powder drop space onto the bottom surface, and a film forming source that makes the film forming material into a film-formable state capable of forming a film on the surface of the powder, and the film forming source is configured to make the film forming material into the film-formable state at least one of a position above the container facing the bottom surface in the vertical direction and inside the container, and to supply the film forming material in the film-formable state to the bottom surface through the powder drop space.

In this powder film-forming device, the film-forming source makes the film-forming material film-formable at least in one of the positions above the container facing the bottom surface in the vertical direction and inside the container, and supplies the film-forming material in the film-formable state to the bottom surface through the powder drop space. In other words, the film-forming material in the film-formable state above the bottom surface can directly act on the powder on the bottom surface by moving downward through the powder drop space, and can efficiently contact the surface of the powder on the bottom surface. Moreover, since the upper transport path of the device body is formed in the container and in an area other than the powder drop space, it does not interfere with the movement of the powder falling toward the bottom surface through the powder drop space, and the powder placed on the bottom surface of the container can be transported upward so as not to interfere with the movement of the film-forming material in the film-formable state that is supplied to the bottom surface through the powder drop space. Therefore, this powder film-forming device transports the powder upward, then returns it to the bottom surface through the powder drop space, creating a smooth powder flow within the container and ensuring that the powder is circulated, efficiently stirring the powder while efficiently bringing the film-forming material in a film-forming state into contact with the powder on the bottom surface, allowing for efficient formation of a film on the powder surface.

It is preferable that the film forming source is configured to supply the film forming material that is in a film forming state to at least a portion of the upper transport path.

In this embodiment, the film-forming material that has become film-formable is not only supplied to the bottom surface of the container, but also to at least a portion of the upper transport path within the container. As a result, the film-forming process is performed not only on the powder on the bottom surface, but also on at least a portion of the powder on the upper transport path. This makes it possible to form a film on the surface of the powder more efficiently. Specific examples of the film-forming material that has become film-formable can be supplied to at least a portion of the upper transport path include the following. For example, when there is no obstruction between at least a portion of the upper transport path and the position where the film-forming source puts the film-forming material into a film-formable state, the film-forming material that has become film-formable can be supplied to at least the portion of the upper transport path.

In the powder deposition device, the upward transport path includes a spiral transport path that extends upward from the bottom surface, the device body further includes a vibration generating unit that operates to transport the powder placed on the bottom surface upward along the spiral transport path by vibrating the container, and the powder drop space is preferably a space radially inward of the container relative to the spiral transport path.

In this embodiment, the spiral conveying path for conveying the powder upward is formed in a spiral shape, so that the powder drop space can be formed in an area inside the spiral conveying path, that is, in an area near the center of the container (for example, an area including the central axis of the container). Therefore, in this embodiment, the radially outer area in the container that does not interfere with the powder falling toward the bottom surface through the powder drop space and the film-forming material that has become film-formable moving toward the bottom surface through the powder drop space is used as an area for providing the spiral conveying path, and the powder on the bottom surface can be conveyed upward along the spiral conveying path by the vibration of the container. In this embodiment, if there is nothing between at least a part of the spiral conveying path and the position where the film-forming source makes the film-forming material in a film-formable state, the film-forming material that has become film-formable can be supplied to that part of the spiral conveying path, and the powder on that part of the spiral conveying path can be subjected to a film-forming process.

In the powder deposition device, it is preferable that the vibration generating unit is configured to be capable of vibrating the container in a direction including a component in the direction of the central axis of the container and a component in the circumferential direction around the central axis.

In this embodiment, the powder can be efficiently moved upward along the spiral transport path by vibrating the container in a direction that contains the above-mentioned components.

In the powder deposition device, it is preferable that the upper conveying path further includes an inner guide path extending from the upper end of the spiral conveying path so that the powder conveyed to the upper end of the spiral conveying path can be guided to a region radially inward from the upper end.

In this embodiment, the inner guide path can further guide the powder transported to the upper end of the spiral transport path to a region radially inward from the upper end. This allows the drop point on the bottom surface of the powder falling from the tip of the inner guide path to be closer to the center of the bottom surface. Therefore, a powder flow is formed in which the powder moves from the center of the bottom surface to the radially outer side of the bottom surface, and the moved powder reaches the entrance of the spiral transport path. As a result, the occurrence of a situation in which the powder is locally retained on the bottom surface is suppressed. This makes it possible to reliably circulate the powder in the container in the powder movement path that is continuous in the order of the center of the bottom surface, the radially outer region of the bottom surface, the spiral transport path, the inner guide path, and the powder drop space. This further promotes the stirring of the powder.

In addition, in this embodiment, the powder transported sequentially along the spiral transport path and the inner guide path sequentially falls from the tip of the inner guide path to near the center of the bottom surface, and then moves radially outward on the bottom surface. By sequentially dropping the powder to near the center of the bottom surface and moving the powder radially outward on the bottom surface, the powder can be dispersed over a wide area of the bottom surface. When the powder is dispersed over a wide area of the bottom surface, the surface area of the powder on the bottom surface that can come into contact with the film-forming material that has become film-formable increases, and the powder on the bottom surface can efficiently capture the film-forming material. This can further improve the efficiency of film formation on the powder surface.

It is more preferable that the inner guideway includes a portion that slopes downward toward the tip of the inner guideway.

In this embodiment, since the inner guide path includes a downwardly sloping portion as described above, the distance between the tip of the inner guide path and the center of the bottom surface can be made smaller. This prevents the powder falling from the tip of the inner guide path from diffusing to the surroundings before it reaches the bottom surface, making it easier to move the point at which the powder falls on the bottom surface closer to a desired position (e.g., the center of the bottom surface).

Furthermore, the powder on the inclined portion as described above is more likely to move toward the tip of the inner guideway due to the action of gravity than, for example, powder on a horizontal surface. Therefore, even if the vibration generating unit vibrates the container in a direction including, for example, a component in the direction of the central axis and a component in the circumferential direction around the central axis, the powder on the inner guideway is reliably transported toward its tip. Specifically, it is as follows. The inner guideway extends from the upper end of the spiral transport path so that the powder transported to the upper end of the spiral transport path can be guided to a region radially inward from the upper end, and since the tip of the inner guideway is located closer to the central axis than the spiral transport path, the circumferential vibration component in the inner guideway becomes smaller toward the tip of the inner guideway. Therefore, since the vibration in the direction of the central axis is the main vibration near the tip of the inner guideway, it may be difficult to transport the powder on the inner guideway toward its tip. Even in such a case, the powder on the inner guideway can be reliably transported toward its tip by the inner guideway including the inclined portion as described above.

In the powder deposition device, it is preferable that the bottom surface of the container includes an inclined surface that slopes downward from the center of the bottom surface toward the outside in the radial direction, and the inner guide path is arranged so that the drop point of at least a portion of the powder falling from the tip of the inner guide path is the center of the bottom surface.

In this embodiment, the powder that falls from the tip of the inner guide path and reaches the center of the bottom surface is efficiently moved radially outward along the inclined surface of the bottom surface by the vibration of the container. This more effectively creates a powder flow in which the powder moves from the center of the bottom surface to the radially outer side of the bottom surface, and the moved powder reaches the entrance of the spiral conveying path. As a result, the occurrence of a situation in which the powder is locally retained on the bottom surface is further suppressed, and the mixing of the powder is further promoted. This makes it possible to reliably circulate substantially all of the powder in the container along the powder movement path that is continuous in the order of the center of the bottom surface, the radially outer area of the bottom surface, the spiral conveying path, the inner guide path, and the powder drop space.

It is preferable that the spiral conveying path has a shape that, in a plan view, gradually moves away from the center of the container as it moves upward.

In this embodiment, the overlap between the upper region of the spiral conveying path and the lower region of the spiral conveying path in plan view can be reduced, compared to a spiral conveying path that describes a spiral shape so that the distance from the center of the container is constant. In other words, in this embodiment, the lower region of the spiral conveying path can be positioned radially inward relative to the upper region of the spiral conveying path in plan view, so that the film-forming material that is ready for film formation is efficiently supplied not only to the powder in the upper region of the spiral conveying path, but also to the powder in the lower region of the spiral conveying path.

The powder deposition device is a device that performs a deposition process on the surface of powder by sputtering, and the deposition source includes a cathode for the sputtering, and the cathode may be disposed in a position that faces the bottom surface in the vertical direction through the powder drop space.

In this embodiment, the powder placed on the bottom surface and the cathode can be arranged to face each other in the vertical direction with the powder falling space in between. This allows the particles (e.g., atoms or molecules) flying out from the cathode to efficiently come into contact with the powder placed on the bottom surface and the powder falling through the powder falling space. As a result, a film can be efficiently formed on the surface of the powder.

The powder deposition device is a device that performs a film deposition process on the surface of powder by sputtering, and the deposition source may include at least one rotary cathode for the sputtering.

The powder film forming device is a device that performs a film forming process on the surface of powder by sputtering, and the film forming source includes at least one rotary cathode for the sputtering, and the at least one rotary cathode includes a cylindrical target, and it is preferable that the target is arranged in such a manner that the central axis of the target faces the vertical direction and at least a portion of the target faces the spiral transport path in the horizontal direction.

In this embodiment, the target is positioned so that its central axis faces the vertical direction, and at least a portion of the target faces the horizontal direction relative to the spiral transport path, so that the film-forming material that is ready for film formation is efficiently supplied to the powder in the spiral transport path.

The powder coating device is a device that performs a coating process on the surface of powder by arc ion plating, and the coating source includes a cathode for the arc ion plating, and the cathode may be disposed in a position that faces the bottom surface in the vertical direction through the powder drop space.

In this embodiment, the powder placed on the bottom surface and the cathode can be arranged to face each other in the vertical direction with the powder falling space in between. This allows the particles (e.g., ions) evaporated from the cathode to efficiently come into contact with the powder placed on the bottom surface and the powder falling through the powder falling space. As a result, a film can be efficiently formed on the surface of the powder.

In the powder deposition device, it is preferable that the area of the bottom surface that overlaps with the powder drop space in a plan view is large enough to include the cathode within the area in a plan view.

In a film formation process using sputtering or arc ion plating, particles (e.g., atoms or molecules) ejected from the cathode or particles (e.g., ions) evaporated from the cathode do not only move downward parallel to the vertical direction from the cathode, but also move diagonally downward at a certain angle relative to the vertical direction, diffusing as they move. Therefore, by making the area of the bottom surface that overlaps with the powder drop space in a plan view larger than the cathode, the particles can come into contact with the powder over a wider area of the bottom surface. As a result, a film can be formed more efficiently on the surface of the powder.

The powder deposition device is a device that performs a film deposition process on the surface of powder by plasma CVD, and the deposition source includes a plasma source for making the raw material gas as the deposition material into a state in which a film can be formed, and the plasma source may be disposed in a position that faces the bottom surface in the vertical direction through the powder drop space.

In this embodiment, the powder placed on the bottom surface and the plasma source can be arranged to face each other in the vertical direction with the powder falling space in between. This allows the raw material gas that has been made into a film-forming state by the plasma source to efficiently come into contact with the powder placed on the bottom surface and the powder falling through the powder falling space. As a result, a film can be efficiently formed on the surface of the powder. In this embodiment, the raw material gas that has been made into a film-forming state is, for example, a product generated by the raw material gas being decomposed by the action of the plasma source on the raw material gas.

It is preferable that the powder deposition device further includes a raw material gas supply unit that supplies the raw material gas to an area affected by the plasma source.

In this embodiment, the raw material gas supplied from the raw material gas supply unit becomes ready for film formation in the area affected by the plasma source (e.g., the area directly below the plasma source), and then contacts the powder on the bottom surface. This allows a film to be efficiently formed on the surface of the powder.

In the powder deposition apparatus, it is preferable that the plasma source has an opening formed at the bottom of the plasma source for discharging the plasma generated inside the plasma source to the outside of the plasma source.

In this embodiment, the source gas is decomposed by the plasma emitted through an opening formed at the bottom of the plasma source, and can be efficiently converted into a state suitable for film formation.

In the powder deposition apparatus, it is preferable that the raw material gas supply unit has a pipe arranged in a ring shape so as to surround the opening of the plasma source in a plan view, and is configured so that the raw material gas can be supplied below the plasma source from a gas supply hole formed in the pipe.

In this embodiment, the pipe of the raw material gas supply unit is arranged to surround the opening of the plasma source in a plan view, so that the pipe does not interfere with the downward movement of the plasma emitted from the opening. This allows the raw material gas supplied below the plasma source from the supply hole of the pipe to come into efficient contact with the plasma emitted from the opening of the plasma source.

In the powder deposition device, it is preferable that the area of the bottom surface that overlaps with the powder drop space in a plan view has a size such that the opening of the plasma source is included within the area in a plan view.

In a film formation process using plasma CVD, the raw material gas that has been made into a film-forming state by the plasma source not only moves downward parallel to the vertical direction from directly below the opening of the plasma source, but also moves so as to diffuse diagonally downward at a certain angle range with respect to the vertical direction. Therefore, by making the area of the bottom surface that overlaps with the powder drop space in a plan view larger than the opening of the plasma source, the raw material gas that has been made into a film-forming state can come into contact with the powder over a wider area of the bottom surface. As a result, a film can be formed on the surface of the powder more efficiently.

It is preferable that the powder film forming apparatus further includes an inert gas supply unit that supplies an inert gas into the container so that the raw material gas that has become capable of film formation is guided toward the bottom surface in the powder falling space.

In this embodiment, the raw material gas that has been made into a film-forming state by the plasma source is guided to the bottom surface by the inert gas supplied from the inert gas supply unit. This allows a film to be formed on the surface of the powder more efficiently.

The powder deposition apparatus further includes a vacuum chamber that houses the container, the container having an upwardly open shape, and it is preferable that the deposition material is in the deposition-enabling state at least either above the container or inside the container in the vacuum chamber.

In this embodiment, by forming a series of powder flows as described above in the vacuum chamber, the powder can be efficiently stirred while the film-forming material that is ready for film formation can be efficiently brought into contact with the powder on the bottom surface in the vacuum chamber. Therefore, in this embodiment, a film can be efficiently formed on the surface of the powder in a vacuum atmosphere.

In the powder deposition apparatus, it is preferable that the vacuum chamber has an internal space that accommodates the container, an upwardly opening chamber body, and a lid portion that is attached to the top of the chamber body in an openable and closable manner.

In this embodiment, the film formation process can be performed with the lid portion closing the top of the chamber body, and consumable parts such as the target can be easily replaced with the lid portion open.

The powder deposition apparatus further includes a vacuum chamber that houses the container, the upward transport path includes a spiral transport path that extends upward in a spiral shape from the bottom surface, and the device body further includes a vibration generating unit that operates to transport the powder placed on the bottom surface upward along the spiral transport path by vibrating the container, the vibration generating unit includes a generator body that generates vibrations and a shaft that connects the generator body and the container, and it is preferable that the generator body is disposed outside the vacuum chamber.

In this embodiment, the vibration generating unit's main body is positioned outside the vacuum chamber, which helps prevent deterioration in the quality of the film formed on the powder.

The powder film forming method according to the present disclosure is a method of performing a film forming process on the surface of powder using the powder film forming device, and includes the steps of placing powder in the container, transporting the powder in the container along the upward transport path, causing the powder transported upward to fall onto the bottom surface through the powder drop space, and forming a film of the film forming material that has become ready for film forming on the surface of the powder.

In this method, the powder can be efficiently stirred in a container for performing a film-forming process on the powder surface, thereby efficiently forming a film on the powder surface.

According to the present disclosure, a powder film forming apparatus and a powder film forming method are provided that can efficiently form a film on the surface of a powder by efficiently stirring the powder in a container for performing a film forming process on the powder.

1 is a side view showing a powder film forming apparatus according to a first embodiment, with a portion thereof depicted in cross section. 2 is a perspective view showing a container and a powder moving mechanism in the main body of the powder film forming apparatus according to the first embodiment; FIG. 2 is a schematic diagram showing a chamber body and a lid of a vacuum chamber of the powder film formation apparatus according to the first embodiment. FIG. 3 is a schematic plan view for explaining the positional relationship between a cathode, a bottom surface of a container, and an upper transport path of the powder film forming apparatus according to the first embodiment; FIG. 1 is a schematic cross-sectional view showing a powder film forming apparatus according to a first embodiment. FIG. 11 is a schematic cross-sectional view showing a powder film forming apparatus according to a second embodiment. FIG. 11 is a schematic cross-sectional view showing a powder film forming apparatus according to a third embodiment. 13 is a schematic plan view for explaining the positional relationship between an opening in a plasma source of a powder film forming apparatus according to a third embodiment, a bottom surface of a container, a pipe of a raw material gas supply unit, and an upper transport path. FIG. FIG. 2 is a side view showing a powder film forming apparatus according to a first modified example of the first embodiment, with a portion thereof depicted in cross section. 10 is a cross-sectional view taken along line XX in FIG. 9. FIG. 11 is a side view showing a powder film forming apparatus according to a second modified example of the first embodiment, with a portion thereof depicted in cross section. 12 is a cross-sectional view taken along line XII-XII in FIG. 11 . FIG. 11 is a side view showing a powder film forming apparatus according to a third modified example of the first embodiment, with a portion thereof depicted in cross section. 14 is a cross-sectional view taken along line XIV-XIV in FIG. 13. FIG. 11 is a side view showing a powder film forming apparatus according to a fourth modified example of the first embodiment, with a portion thereof depicted in cross section. FIG. 13 is a side view showing a powder film forming apparatus according to a fifth modified example of the first embodiment, with a portion thereof depicted in cross section.

Below, a powder film forming apparatus and a powder film forming method according to an embodiment of the present disclosure will be described with reference to the drawings. The powder film forming apparatus according to this embodiment is an apparatus for forming a film on the surface of powder by a film forming method such as PVD (physical vapor deposition) or CVD (chemical vapor deposition). Specifically, examples of PVD include sputtering and arc ion plating. Examples of CVD include plasma CVD.

[First embodiment]
Fig. 1 is a side view of a powder film forming apparatus 1 according to a first embodiment, with a portion of the apparatus drawn in cross section. Fig. 2 is a perspective view showing a container and a powder moving mechanism of the powder film forming apparatus 1. Fig. 3 is a schematic diagram showing a chamber body and a lid of a vacuum chamber of the powder film forming apparatus 1. Fig. 4 is a schematic plan view for explaining the positional relationship between the cathode of the powder film forming apparatus 1, the bottom surface of the container, and the upper transport path. Fig. 5 is a schematic cross-sectional view showing the powder film forming apparatus 1.

The powder deposition device 1 according to the first embodiment is a device that performs a deposition process on the surface of powder by sputtering.

As shown in Figures 1 to 5, the powder deposition device 1 includes an apparatus main body, a vacuum chamber 40, a sputtering unit 50, an inert gas supply unit 70 (see Figure 5), and a support table 90 that supports these. The apparatus main body includes a container 10 and a powder moving mechanism 30.

The container 10 is a cylindrical container having a bottom and a side wall. The container 10 has an upwardly open shape. The container 10 has a bottom surface 13, which is the upper surface of the bottom, and an inner surface 14, which is the inner surface of the side wall.

The bottom surface 13 is a surface on which powder F to be supplied into the container 10 at the start of the film formation process can be placed. The bottom surface 13 includes an inclined surface. This inclined surface inclines downward from the center of the bottom surface 13 (the portion through which the central axis A of the cylindrical container 10 passes) toward the outside in the radial direction of the container 10. In this embodiment, the inclined surface is formed continuously from the center of the bottom surface 13 to the outer periphery of the bottom surface 13. A powder drop space S is formed within the container 10. This powder drop space S is a space for dropping powder F toward the bottom surface 13 within the container 10 when the film formation process is performed, and is a space that continues upward from the bottom surface 13. Details of the powder drop space S will be described later.

The inner surface 14 has a circular shape in a plan view and is a surface that rises upward from the outer periphery of the bottom surface 13. The spiral conveying path 31A, which will be described later, is attached to this inner surface 14.

The powder moving mechanism 30 is configured to transport the powder F arranged on the bottom surface 13 upward and to allow the transported powder F to fall onto the bottom surface 13 through the powder fall space S. The powder moving mechanism 30 has an upward transport path 31 and a vibration generating unit 32 (vibration generating device).

The upper conveying path 31 is formed in an area of the container 10 other than the powder drop space S, and is a path along which the powder F is conveyed. The upper conveying path 31 includes a spiral conveying path 31A and an inner guide path 31B. In this embodiment, the upper conveying path 31 is a separate component from the container 10, but may also constitute a part of the container 10 as in variant example 3 described below.

2, 4 and 5, the spiral conveying path 31A extends upward from the bottom surface 13 in a spiral shape along the inner surface 14 of the container 10. The lower end of the spiral conveying path 31A is located adjacent to the outer periphery of the bottom surface 13, and the upper end of the spiral conveying path 31A is located adjacent to the inner surface 14 above the bottom surface 13. Specifically, the upper end of the spiral conveying path 31A is provided at a position adjacent to the inner surface 14 at the upper part of the container 10 (near the upper end of the container 10). The spiral conveying path 31A has an upper surface on which the powder F is placed. The outer edge (radially outer edge) of the upper surface of the spiral conveying path 31A is connected to the inner surface 14 of the container 10. The spiral conveying path 31A has a gradient such that the position becomes higher from the lower end to the upper end.

The inner guide path 31B extends from the upper end of the spiral conveying path 31A so as to guide the powder F conveyed to the upper end of the spiral conveying path 31A to a region radially inward of the upper end of the container 10. As shown in FIG. 2, the inner guide path 31B has an upper surface on which the powder F is placed, and a pair of side surfaces that rise upward from a pair of edges located on both sides of the upper surface. The inner guide path 31B is arranged so that the drop point of at least a part of the powder F falling from the tip of the inner guide path 31B is the center of the bottom surface 13. Specifically, as shown in FIG. 4, the tip of the inner guide path 31B is located near the central axis A of the container 10 in a plan view. The inner guide path 31B has a curved shape (e.g., an arc shape) in a plan view, but may include a part that extends linearly.

The vibration generating unit 32 vibrates the container 10 to transport the powder F placed on the bottom surface 13 upward along the spiral transport path 31A, and also operates to guide the powder F that reaches the upper end of the spiral transport path 31A along the inner guide path 31B to the tip of the inner guide path 31B.

The vibration generating unit 32 includes a generating unit main body 321 and a shaft 322. The shaft 322 interconnects the generating unit main body 321 and the container 10. The upper part of the shaft 322 is connected to the bottom of the container 10. This allows the generating unit main body 321 to transmit vibrations to the container 10 via the shaft 322, causing the container 10 to vibrate.

The vibration generating unit 32 is configured to be able to vibrate the container 10 in a direction including a component in the direction of the central axis A of the container 10 (up and down direction) and a component in the circumferential direction around the central axis A. Specifically, the vibration generating unit 32 may vibrate the container 10 so that the container 10 reciprocates in a first direction including a component in one circumferential direction and an upward component, and a second direction including a component in the other circumferential direction and a downward component. The vibration generating unit 32 may also vibrate the container 10 so that the container 10 alternately moves in a direction including a component in one circumferential direction and an upward component, and a direction including a component in one circumferential direction and a downward component. By vibrating the container 10 in a direction including such components, the powder F can be efficiently transported upward along the spiral transport path 31A as shown by the arrow in FIG. 2, and efficiently guided radially inward along the inner guide path 31B. The powder F that reaches the end of the inner guide path 31B falls toward the bottom surface 13 in the powder fall space S.

As described above, the powder drop space S is a space for dropping the powder F toward the bottom surface 13 in the container 10. In this embodiment, the powder drop space S is a space radially inward of the container 10 from the spiral conveying path 31A. Specifically, the powder drop space S is a space radially inward of the container 10 from the spiral conveying path 31A, and is a space below the downstream end of the upper conveying path 31 in the conveying direction. In this embodiment, the downstream end of the upper conveying path 31 in the conveying direction is the end of the inner guide path 31B. This powder drop space S is a space that is continuous in the vertical direction from the bottom surface 13 to the end of the upper conveying path 31 (the end of the inner guide path 31B).

The vacuum chamber 40 forms an internal space that houses the container 10. The vacuum chamber 40 has a chamber body 41 and a lid 42. The chamber body 41 is, for example, a cylindrical container having a bottom. The chamber body 41 has a shape that opens upward. The lid 42 can open and close the opening at the top of the chamber body 41. As shown in FIG. 3, the lid 42 is attached to the top of the chamber body 41 via a hinge 43 so that it can be opened and closed. A pipe 411 for drawing a vacuum is connected to the side of the chamber body 41. The end of the pipe 411 (not shown) is connected to a pump for drawing a vacuum.

As shown in FIG. 1, the lid 42 has a disk-shaped lid body 421 and an attachment portion 422 provided in the center of the lid body 421. The attachment portion 422 is a portion to which the target 52, which will be described later, is detachably attached. When the lid 42 closes the upper opening of the chamber body 41 with the target 52 attached to the attachment portion 422, the target 52 is positioned above the vessel 10 in the vacuum chamber 40. Specifically, in this state, the target 52 is positioned so as to face the bottom surface 13 of the vessel 10 in the vertical direction with a vertical gap therebetween. As a result, the vacuum chamber 40 contains the vessel 10 and the target 52 in its internal space.

The sputtering unit 50 includes the target 52 described above and various components such as a cooling mechanism housed in the case 51. In the powder deposition apparatus 1 that performs a film deposition process on the surface of the powder by sputtering, the target 52 constitutes a cathode or a part of the cathode. The container 10 or the vacuum chamber 40 may constitute an anode. When the powder deposition apparatus 1 is an apparatus that performs a film deposition process on the surface of the powder by magnetron sputtering, for example, the sputtering unit 50 includes a magnet. In this case, the magnet is disposed adjacent to the target 52 (for example, directly above the target 52).

The inert gas supply unit 70 is for supplying an inert gas into the vacuum chamber 40 when the film formation process is performed (see FIG. 5). The inert gas from the inert gas supply unit 70 may be supplied into the vacuum chamber 40, for example, through the same piping as the vacuum piping 411 connected to the pump, or may be supplied into the vacuum chamber 40 through a supply piping (not shown) provided separately from the vacuum piping 411. For example, argon gas is used as the inert gas.

Next, a method of performing a film formation process on the surface of the powder F by sputtering will be described. First, with the lid 42 open to the chamber body 41, the target 52 is attached to the lid 42 of the vacuum chamber 40, and a predetermined amount of powder F is placed on the bottom surface 13 of the container 10. After that, the lid 42 is closed so as to block the opening at the top of the chamber body 41. Next, after evacuation is performed in the vacuum chamber 40, an inert gas (e.g., argon gas) is supplied into the vacuum chamber 40. In this state, a glow discharge occurs when an external power source (e.g., a direct current power source) applies positive and negative voltages to the anode and the target 52 (cathode), respectively, and a plasma region P is generated near the target, and the inert gas is ionized. The ionized inert gas collides with the target 52, and the particles E (e.g., atoms or molecules) that constitute the target 52 are knocked out by the kinetic energy. A part of the particles E knocked out from the target 52 moves downward in the powder drop space S and adheres to the surface of the powder F on the bottom surface 13. In this embodiment, as shown in FIG. 2 and FIG. 5, there is no obstruction between at least a part of the spiral transport path 31A and the lower surface of the target 52, which is the position where the film-forming material is in a film-forming state. Therefore, another part of the particles E knocked out from the target 52 moves toward the at least a part of the spiral transport path 31A in the powder drop space S and adheres to the surface of the powder F thereon. This allows the film-forming process to be performed on the surface of the powder F on the bottom surface 13 and on the surface of the powder F on the at least a part of the spiral transport path 31A. The inert gas also has a function (action) of maintaining the plasma state in the plasma region P.

In this embodiment, the target 52 constituting the cathode, the anode, and the inert gas supply unit 70 are an example of a film-forming source that makes the film-forming material in a film-forming state capable of forming a film on the surface of the powder F. Specifically, the target 52, the anode, and the inert gas supply unit 70 make the film-forming material in the film-forming state on the lower surface of the target 52, and supply the film-forming material E in the film-forming state to the powder F on the bottom surface 13 through the powder drop space S. The material constituting the target 52 is an example of a film-forming material, and the particles E knocked out from the target 52 (particles E flying out from the target 52) are an example of a film-forming material in a film-forming state. The position of the lower surface of the target 52 is an example of a position facing the bottom surface 13 in the vertical direction through the powder drop space S. The position of the lower surface of the target 52 is also an example of a position facing the bottom surface 13 in the vertical direction above the container 10. The lower surface of the target 52 may be located inside the container 10. In this case, the target 52 as the film-forming source, the anode, and the inert gas supply unit 70 are configured to bring the film-forming material to the film-forming state on the lower surface of the target 52 located inside the container 10, and supply the film-forming material in the film-forming state to the powder on the bottom surface 13.

As described above, in the powder film forming apparatus 1 and the powder film forming method according to the first embodiment, the target 52 is arranged to face the bottom surface 13 in the vertical direction through the powder drop space S, so that the film forming source including the target 52 can put the film forming material into a film-forming state at a position facing the bottom surface 13 in the vertical direction through the powder drop space S. The film forming material E that has been put into a film-forming state by the film forming source can move toward the bottom surface 13 in the vertical direction or in a direction inclined thereto through the powder drop space S. Therefore, the film forming material E that has been put into a film-forming state above the bottom surface 13 can directly act on the powder F on the bottom surface 13 and can efficiently contact the surface of the powder F on the bottom surface 13. In addition, in this embodiment, the film forming material E that has been put into a film-forming state can also contact the surface of the powder F on at least a part of the spiral transport path 31A, and can also contact the surface of the powder F on the inner guide path 31B. Moreover, since the upper conveying path 31 of the powder moving mechanism 30 is formed in an area other than the powder drop space S within the container 10, it does not interfere with the movement of the powder F falling toward the bottom surface 13 through the powder drop space S, and does not interfere with the movement of the film-forming material E that is ready for film formation and is supplied to the powder F on the bottom surface 13 through the powder drop space S. Therefore, this powder film-forming device 1 conveys the powder F upward, and returns the conveyed powder F to the bottom surface 13 through the powder drop space S to form a series of smooth flows of the powder F, thereby reliably circulating the powder F, and efficiently agitating the powder F while efficiently bringing the film-forming material E that is ready for film formation into contact with the powder F on the bottom surface 13, thereby efficiently forming a film on the surface of the powder F. Note that, until the film-forming operation of the powder film-forming device 1 is stopped, the series of movements of the powder F, in which the powder F is conveyed upward from the bottom surface 13 and the conveyed powder F falls to the bottom surface 13, may be repeated multiple times.

In addition, in the first embodiment, the powder F placed on the bottom surface 13 and the target 52 can be arranged to face each other in the vertical direction via the powder drop space S. This allows the particles E flying out from the target 52 to efficiently come into contact with the powder F placed on the bottom surface 13 and the powder F falling through the powder drop space S. As a result, a film can be efficiently formed on the surface of the powder F.

In the first embodiment, as shown in FIG. 4, the area of the bottom surface 13 that overlaps with the powder drop space S in a planar view has a size such that the target 52 is included within the range of the area in a planar view. In other words, the area of the bottom surface 13 that is radially inward from the spiral transport path 31A in a planar view has a size such that the target 52 is included within the range of the area in a planar view. In a film formation process by sputtering, the particles E that fly out from the target 52 that constitutes the cathode not only move downward parallel to the vertical direction from the target 52, but also move so as to diffuse diagonally downward inclined at a certain angle range with respect to the vertical direction. Therefore, by making the area of the bottom surface 13 that overlaps with the powder drop space S in a planar view larger than the target 52, the particles E can be brought into contact with the powder F over a wider range on the bottom surface 13. As a result, a film can be formed on the surface of the powder F more efficiently.

In addition, by forming the spiral conveying path 31A for conveying the powder F upward in a spiral shape along the inner surface 14 of the container 10, the powder drop space S can be formed in an area inside the spiral conveying path 31A, i.e., an area near the center of the container 10 (an area including the central axis A of the cylindrical container 10). Therefore, the spiral conveying path 31A can be provided in the radially outer area of the container 10, which does not interfere with the powder F falling toward the bottom surface 13 through the powder drop space S and the film-forming material E that has become film-formable moving toward the bottom surface through the powder drop space S, and the powder F on the bottom surface 13 can be conveyed upward along the spiral conveying path 31A by the vibration of the container 10.

The upper conveying path 31 further includes an inner guide path 31B extending from the upper end of the spiral conveying path 31A so that the powder F conveyed to the upper end of the spiral conveying path 31A can be guided to a region radially inward from the upper end by the inner guide path 31B. This allows the drop point on the bottom surface 13 of the powder F falling from the tip of the inner guide path 31B to be closer to the center of the bottom surface 13.

The powder F that falls from the tip of the inner guide path 31B and reaches the center of the bottom surface 13 is efficiently moved radially outward along the inclined surface of the bottom surface 13 by the vibration of the container 10. This effectively creates a flow of powder F in which the powder F moves radially outward from the center of the bottom surface 13 and reaches the entrance of the spiral conveying path 31A. As a result, the powder F is prevented from being locally stagnated on the bottom surface 13, and the mixing of the powder F is further promoted.

The inner guide path 31B may also include a portion that slopes downward toward the tip of the inner guide path 31B. In this case, the distance between the tip of the inner guide path 31B and the center of the bottom surface 13 can be made smaller. This prevents the powder F from diffusing to the surroundings before it falls from the tip of the inner guide path 31B and reaches the bottom surface 13, making it easier to move the drop point of the powder F on the bottom surface 13 closer to the center of the bottom surface 13. Only a portion of the inner guide path 31B may slope downward, or the entire inner guide path 31B may slope downward.

The vacuum chamber 40 has an internal space that accommodates the container 10, a chamber body 41 that opens upward, and a lid portion 42 that is attached to the upper part of the chamber body 41 in an openable and closable manner, and the target 52 is attached to the lid portion 42 in a detachable manner. Therefore, the film formation process can be performed with the lid portion 42 closing the upper part of the chamber body 41, and the target 52 can be easily replaced with the lid portion 42 open. In this embodiment, as described above, the vibration generating unit 32 vibrates the container 10 to transport the powder F arranged on the bottom surface 13 upward along the upper transport path 31, and the transported powder F falls to the bottom surface 13 through the powder falling space S. This makes it possible to simplify the mechanism for creating a vacuum in the vacuum chamber 40, since the rotating sliding portion that rotatably supports the rotary barrel-type sputtering chamber of Patent Document 1 is no longer necessary.

Second Embodiment
FIG. 6 is a schematic cross-sectional view showing a powder film forming apparatus 1 according to the second embodiment.

The powder coating device 1 according to the second embodiment is a device that applies a coating process to the surface of powder by arc ion plating.

The powder deposition device 1 according to the second embodiment includes a device main body, a vacuum chamber 40, an ion plating unit 50A, and a support table 90 that supports these. The device main body includes a container 10 and a powder moving mechanism 30.

The configurations of the container 10, powder moving mechanism 30, vacuum chamber 40, and support table 90 of the powder deposition apparatus 1 according to the second embodiment are similar to those of the powder deposition apparatus 1 according to the first embodiment shown in Figures 1 to 5, and therefore illustrations and descriptions of these are omitted. Below, the differences between the powder deposition apparatus 1 according to the second embodiment and the first embodiment will be mainly described.

The ion plating unit 50A includes a target 52 and various components such as a magnet and a cooling mechanism housed in a case 51A. In a powder film forming apparatus 1 that performs a film forming process on the surface of powder F by arc ion plating, the target 52 constitutes a cathode or a part of a cathode. The anode may be constituted by a container 10. In this case, the cooling mechanism may have a pipe for cooling water that is wrapped around the outer circumference of the container 10. The container 10 is cooled by supplying cooling water to this pipe.

In the film formation process using arc ion plating, a vacuum arc discharge is used to evaporate a solid target 52. Specifically, in this film formation process, in a vacuum atmosphere, the target 52 is used as a cathode, and power is supplied from an external power source (not shown) to generate a vacuum arc discharge between the target 52 and the anode. This causes the film formation material that constitutes the target 52 to evaporate from the surface of the target 52 and become ionized. The ionized film formation material E is supplied to the powder F on the bottom surface 13, and thus a film is formed on the surface of the powder F.

In this second embodiment, the target 52 constituting the cathode and the anode are an example of a film-forming source that makes the film-forming material in a film-forming state capable of forming a film on the surface of the powder F. Specifically, the target 52 and the anode make the film-forming material in the film-forming state on the lower surface of the target 52, and supply the film-forming material in the film-forming state to the powder F on the bottom surface 13 through the powder drop space S. The material constituting the target 52 is an example of a film-forming material, and the film-forming material E evaporated and ionized from the surface of the target 52 is an example of a film-forming material in a film-forming state. The position of the lower surface of the target 52 is an example of a position that faces the bottom surface 13 in the vertical direction through the powder drop space S. The position of the lower surface of the target 52 is also an example of a position that faces the bottom surface 13 in the vertical direction above the container 10. The lower surface of the target 52 may be located inside the container 10.

As with the first embodiment, the powder film-forming device 1 according to the second embodiment efficiently stirs the powder F by transporting the powder F upward and then returning the transported powder F to the bottom surface 13 through the powder drop space S, thereby efficiently bringing the film-forming material E in a film-forming state into contact with the powder F on the bottom surface 13, thereby efficiently forming a film on the surface of the powder F.

In the second embodiment, the powder F and the target 52 placed on the bottom surface 13 can be opposed to each other in the vertical direction through the powder drop space S. Therefore, the film forming source including the target 52 can put the film forming material into a film forming state at a position that faces the bottom surface 13 in the vertical direction through the powder drop space S. This allows the ions evaporated from the target 52 to efficiently contact the powder F placed on the bottom surface 13 and the powder F falling through the powder drop space S. As a result, a film can be efficiently formed on the surface of the powder F. In the second embodiment, similarly to the first embodiment, the film forming material E in a film forming state can also contact the surface of the powder F on at least a part of the spiral transport path 31A, and can also contact the surface of the powder F on the inner guide path 31B. As a result, the film forming process is not only performed on the powder F on the bottom surface 13, but also on the powder F on at least a part of the spiral transport path 31A and the powder F on the inner guide path 31B.

[Third embodiment]
FIG. 7 is a schematic cross-sectional view showing a powder film forming apparatus 1 according to the third embodiment.

The powder film forming apparatus 1 according to the third embodiment is an apparatus that performs a film forming process on the surface of powder F by plasma CVD.

The powder deposition apparatus 1 according to the third embodiment includes an apparatus main body, a vacuum chamber 40, a plasma source 60, a raw material gas supply unit, an inert gas supply unit 70, and a support table 90 that supports these. The apparatus main body includes a container 10 and a powder moving mechanism 30.

The configurations of the container 10, powder moving mechanism 30, vacuum chamber 40, and support table 90 of the powder deposition apparatus 1 according to the third embodiment are similar to those of the powder deposition apparatus 1 according to the first embodiment shown in Figures 1 to 5, so illustrations and explanations of these are omitted. Below, the differences between the powder deposition apparatus 1 according to the third embodiment and the first embodiment will be mainly described.

The plasma source 60 has the function of bringing the raw material gas into a state in which a film can be formed within the vacuum chamber 40. The plasma source 60 includes a case 61, a power supply housed within the case 61, and an electrode or coil. The power supply may be placed outside the plasma source 60.

The raw gas supply unit supplies raw gas as a film forming material into the vacuum chamber 40. In the specific example shown in FIG. 7, the raw gas supply unit has a pipe 62 for supplying raw gas. The pipe 62 supplies raw gas to an area affected by the action of the plasma source 60. Specifically, as shown in FIG. 7, the pipe 62 has multiple gas supply holes on the lower surface of the pipe 62, and is configured to be able to supply raw gas from these gas supply holes below the plasma source 60. When the pipe 62 has an annular shape in a plan view, the multiple gas supply holes are provided, for example, at intervals along the circumferential direction on the lower surface of the pipe 62. It is preferable that the multiple gas supply holes are provided evenly in the circumferential direction. In this case, unevenness in the film forming process can be reduced compared to when the pipe is, for example, a straight pipe.

The raw material gas supplied from the pipe 62 of the raw material gas supply unit is in a state in which a film can be formed in the area affected by the plasma source 60, for example, the area directly below the plasma source 60, such as the area P surrounded by the two-dot chain line P in FIG. 7. The raw material gas E in a state in which a film can be formed is supplied to the powder F on the bottom surface 13. As a result, a film is formed on the surface of the powder F.

Specifically, an opening 63 is provided at the bottom of the plasma source 60. This opening 63 is for discharging plasma generated inside the plasma source 60 to the outside. When plasma is discharged from the opening 63 of the plasma source 60, a plasma region P is formed directly below the plasma source 60. The raw material gas supplied from the pipe 62 of the raw material gas supply unit is decomposed in the plasma region P and becomes in a state in which a film can be formed. That is, in this embodiment, the raw material gas E in a state in which a film can be formed is a product (decomposition product) generated by decomposing the raw material gas by the plasma discharged from the plasma source 60.

In this third embodiment, the plasma source 60 and the raw material gas supply unit are an example of a film formation source that makes the raw material gas as a film formation material in a film-formable state in which a film can be formed on the surface of the powder F. Specifically, the plasma source 60 and the raw material gas supply unit make the film formation material in the plasma region P where the action of the plasma source 60 is applied, and supply the film formation material E in the film-formable state to the powder F on the bottom surface 13 through the powder drop space S. The raw material gas supplied by the raw material gas supply unit is an example of a film formation material. The product generated by decomposing the raw material gas by the plasma emitted from the plasma source 60 is an example of a film formation material in a film-formable state. The plasma region P where the action of the plasma source 60 is applied is located in a position facing the bottom surface 13 in the vertical direction. As shown in FIG. 7, the lower part of this plasma region P may be located in the powder drop space S in the container 10. The upper part of the plasma region P may be located between the container 10 and the plasma source 60, and may be located opposite the bottom surface 13 in the vertical direction across the powder drop space S.

Although not shown, the upper part of the plasma region P may be located inside the container 10. Specifically, for example, the opening 63 of the plasma source 60 or its vicinity may be located near the upper end of the container 10 or inside the container 10. In this case, since the upper part of the plasma region P located immediately below the opening 63 is located inside the container 10, the plasma region P can be brought closer to the bottom surface 13 as a whole. Here, the plasma emitted from the opening 63 of the plasma source 60 not only moves downward parallel to the vertical direction from the opening 63, but also moves so as to diffuse diagonally downward inclined at a certain angle range with respect to the vertical direction. Therefore, if the plasma region P can be brought closer to the bottom surface 13, the proportion of the plasma emitted from the opening 63 that moves toward, for example, the inner surface 14 of the container 10 can be reduced, and the proportion of the plasma that moves toward the bottom surface 13 can be increased. This allows the powder on the bottom surface 13 to be more efficiently film-formed.

As with the first embodiment, the powder film-forming device 1 according to the third embodiment efficiently stirs the powder F by transporting the powder F upward and then returning the transported powder F to the bottom surface 13 through the powder drop space S, thereby efficiently bringing the film-forming material E in a film-forming state into contact with the powder F on the bottom surface 13, thereby efficiently forming a film on the surface of the powder F.

In the third embodiment, the powder F placed on the bottom surface 13 and the plasma source 60 are opposed in the vertical direction through the powder drop space S. Therefore, the film forming source including the plasma source 60 and the raw material gas supply unit can make the raw material gas as the film forming material in a film-forming state at a position facing the bottom surface 13 in the vertical direction through the powder drop space S and in a part of the powder drop space S. This allows the raw material gas E made into a film-forming state by the plasma source 60 to efficiently come into contact with the powder F placed on the bottom surface 13 and the powder F falling through the powder drop space S. As a result, a film can be efficiently formed on the surface of the powder F. In addition, in the third embodiment, as in the first embodiment, the film forming material E made into a film-forming state can also come into contact with the surface of the powder F on at least a part of the spiral transport path 31A, and can also come into contact with the surface of the powder F on the inner guide path 31B. As a result, the film formation process is not only performed on the powder F on the bottom surface 13, but also on the powder F on at least a portion of the spiral conveying path 31A and the powder F on the inner guide path 31B.

Figure 8 is a schematic plan view illustrating the positional relationship between the opening 63 in the plasma source 60 of the powder deposition device 1, the bottom surface 13 of the container 10, the pipe 62 of the raw material gas supply section, and the upper transport path 31.

The opening 63 of the plasma source 60 is formed, for example, on the bottom surface 64 of the case 61. By providing this opening 63 on the bottom surface 64 of the case 61, the action of the plasma source 60 can be more effectively exerted through the opening 63 on the raw material gas supplied below the plasma source 60.

In the powder deposition apparatus 1, the pipe 62 of the raw material gas supply section is arranged in a ring shape so as to surround the plasma source 60 (more specifically, the opening 63 of the plasma source 60) in the plan view shown in FIG. 8. The raw material gas is supplied below the plasma source 60 from multiple gas supply holes formed in the pipe 62.

In this way, the pipe 62 of the raw material gas supply section is arranged to surround the opening 63 of the plasma source 60 in a plan view, so that the pipe 62 does not interfere with the downward movement of the plasma emitted from the opening 63. This allows the raw material gas supplied below the plasma source 60 from the gas supply hole of the pipe 62 to come into contact efficiently with the plasma emitted from the opening 63 of the plasma source 60.

In the specific example shown in FIG. 8, the outer diameter of the annular pipe 62 is smaller than the opening diameter of the container 10 (the inner diameter of the container 10), and the pipe 62 is arranged so as to be contained within the range of the container 10 in a planar view. However, the pipe 62 is not limited to the aspect shown in FIG. 8. The outer diameter of the pipe 62 may be larger than the opening diameter of the container 10, for example. Specifically, the pipe 62 may be arranged so that the container 10 is contained within the inner region of the annular pipe 62 in a planar view, for example.

Also, as shown in FIG. 8, the area of the bottom surface 13 that overlaps with the powder drop space S in plan view is large enough to include the opening 63 provided on the lower surface 64 of the plasma source 60. In other words, the area of the bottom surface 13 that is radially inward from the spiral transport path 31A in plan view is large enough to include the opening 63 of the plasma source 60 within the range of the area in plan view. In FIG. 8, the area occupied by the powder drop space S in plan view (i.e., the area of the bottom surface 13 that overlaps with the powder drop space S in plan view) is shown by a number of dots so that it is easy to distinguish. Note that the area also exists at a position corresponding to the pipe 62 and the inner guide path 31B in plan view, but dots are not added at the positions corresponding to the pipe 62 and the inner guide path 31B.

In a film formation process using plasma CVD, the raw material gas E that has been made into a film-forming state by the plasma source 60 not only moves downward parallel to the vertical direction from directly below the opening 63 of the plasma source 60, but also moves so as to diffuse diagonally downward at a certain angle range with respect to the vertical direction. Therefore, by making the area of the bottom surface 13 that overlaps with the powder drop space S in a plan view larger than the opening 63 provided on the lower surface 64 of the plasma source 60, the raw material gas E that has been made into a film-forming state can come into contact with the powder F over a wider area of the bottom surface 13. As a result, a film can be formed on the surface of the powder F more efficiently.

The inert gas supply unit 70 shown in FIG. 7 supplies inert gas into the container 10 so that the raw material gas E that has become ready for film formation below the plasma source 60 is guided toward the bottom surface 13 in the powder falling space S. As a result, the raw material gas E that has become ready for film formation is guided toward the bottom surface 13 by the inert gas supplied from the inert gas supply unit 70, so that a film can be formed more efficiently on the surface of the powder F. The supplied inert gas also has the function (action) of maintaining the plasma state.

[Modifications 1 to 3 of the first embodiment]
Next, a description will be given of Modifications 1 to 3 of the first embodiment. Each of the powder film forming apparatuses 1 according to Modifications 1 to 3 of the first embodiment is an apparatus that performs a film forming process on the surface of powder by sputtering.

Figure 9 is a side view of a powder deposition apparatus 1 according to Modification 1 of the first embodiment, partially in cross section. Figure 10 is a cross-sectional view taken along line X-X in Figure 9. As shown in Figures 9 and 10, the powder deposition apparatus 1 according to Modification 1 comprises an apparatus main body, a vacuum chamber 40, a sputtering unit 50, an inert gas supply section 70, and a support table 90 that supports these. The apparatus main body includes a container 10 and a powder moving mechanism 30.

The configurations of the container 10, vacuum chamber 40, inert gas supply unit 70, and support table 90 of the powder deposition apparatus 1 according to the modified example 1 are similar to those of the powder deposition apparatus 1 shown in Figures 1 to 5, so detailed descriptions of these will be omitted. Below, the differences between the powder deposition apparatus 1 according to the modified example 1 and the powder deposition apparatus 1 shown in Figures 1 to 5 will be mainly described.

In the first modified example, a first powder drop space S1 and a second powder drop space S2 are formed in the container 10. Each of these powder drop spaces S1 and S2 is a space for dropping powder F toward the bottom surface 13 in the container 10 when a film formation process is performed, and is a space that continues upward from the bottom surface 13. The first powder drop space S1 and the second powder drop space S2 are provided so as to be located apart from each other in the circumferential direction in the container 10. Each of the first powder drop space S1 and the second powder drop space S2 is a space located radially inward of the container 10 from the spiral conveying path 31A. In the specific example shown in FIG. 10, the first powder drop space S1 and the second powder drop space S2 are provided so as to be located radially opposite each other in the container 10.

As shown in Figures 9 and 10, the sputtering unit 50 in variant 1 includes multiple rotary cathodes 53 (specifically, four rotary cathodes 53). Each of the multiple rotary cathodes 53 includes a cylindrical target 54 and a magnet 56 disposed within the target 54.

Each target 54 is supported by a support member (not shown) so that the central axis of the cylinder that constitutes the target 54 faces in the vertical direction and can rotate around the central axis. At least the lower part of each target 54 is disposed within the container 10. The lower end of each target 54 is located below the vertical center of the container 10, and the upper end of each target 54 is located above the vertical center of the container 10. A cooling liquid such as cooling water is supplied into the target 54.

Each magnet 56 has a shape that extends along the direction of the central axis of the target 54 within the corresponding target 54. The magnets 56 form a magnetic field to increase the density of the plasma. The magnets 56 do not rotate with the target 54, but are fixed in a predetermined position as shown in FIG. 10 by a fixing member (not shown). At least the lower part of each magnet 56 is disposed within the vessel 10. The lower end of each magnet 56 is located below the center of the vessel 10 in the vertical direction, and the upper end of each magnet 56 is located above the center of the vessel 10 in the vertical direction.

The four rotary cathodes 53 are arranged at intervals around the central axis A of the container 10 in the circumferential direction. Of the four rotary cathodes 53, two adjacent rotary cathodes 53 in the circumferential direction (the upper two rotary cathodes 53 in FIG. 10) are connected to an AC power supply PS as shown in FIG. 9. When a film formation process is performed, the AC power supply PS alternately applies positive and negative voltages for sputtering to the targets 54 of these two rotary cathodes 53. As a result, a discharge occurs between the two rotary cathodes 53 to form a plasma. For example, in the specific example shown in FIG. 10, in each of the two rotary cathodes 53, the magnet 56 is arranged in a position closer to the first powder drop space S1 than the central axis of the cylinder constituting the target 54. As a result, the two rotary cathodes 53 can locally form a first plasma region P1 at a position corresponding to the first powder drop space S1. The relative position of the magnet 56 with respect to the vessel 10 and the target 54 is set so that at least a portion of the plasma region formed by one rotary cathode 53 overlaps with at least a portion of the plasma region formed by the other rotary cathode 53.

Similarly, the remaining two rotary cathodes 53 adjacent in the circumferential direction (the two lower rotary cathodes 53 in FIG. 10) are connected to an AC power source. When a film formation process is performed, the AC power source alternately applies positive and negative voltages for sputtering to the targets 54 of these two rotary cathodes 53. This causes a discharge between the two rotary cathodes 53 to form a plasma. For example, in the specific example shown in FIG. 10, in each of the two rotary cathodes 53, the magnet 56 is disposed in a position closer to the second powder drop space S2 than the central axis of the cylinder constituting the target 54. This allows the two rotary cathodes 53 to locally form a second plasma region P2 at a position corresponding to the second powder drop space S2. The relative positions of the magnet 56 with respect to the container 10 and the target 54 are set so that at least a part of the plasma region formed by one rotary cathode 53 and at least a part of the plasma region formed by the other rotary cathode 53 overlap.

The powder moving mechanism 30 is configured to transport the powder F arranged on the bottom surface 13 of the container 10 upward and to allow the transported powder F to fall onto the bottom surface 13 through the powder falling space S. The powder moving mechanism 30 has an upward transport path 31 and a vibration generating unit 32.

The upper conveying path 31 is formed in an area of the container 10 other than the powder drop space S, and is a path along which the powder F is conveyed. The upper conveying path 31 includes a spiral conveying path 31A and at least one guide wall (for example, two guide walls 311 and 312 described below).

The spiral conveying path 31A in the first modification is similar to the spiral conveying path 31A shown in Figures 2, 4, and 5. That is, as shown in Figures 9 and 10, the spiral conveying path 31A extends spirally upward from the bottom surface 13 along the inner surface 14 of the container 10. The spiral conveying path 31A has a gradient such that the position becomes higher from the lower end to the upper end.

The at least one guide wall is provided on the spiral conveying path 31A so as to guide the powder F conveyed upward along the spiral conveying path 31A to the inside (diametrically inward) of the spiral conveying path 31A and to allow the powder F to fall from the spiral conveying path 31A toward the bottom surface 13. In the specific example shown in FIG. 10, the at least one guide wall includes a first guide wall 311 provided at the upper part of the spiral conveying path 31A and a second guide wall 312 provided at a portion upstream in the conveying direction in the spiral conveying path 31A from the first guide wall 311. The first guide wall 311 and the second guide wall 312 are provided at positions corresponding to the first powder drop space S1 and the second powder drop space S2, respectively. The first guide wall 311 and the second guide wall 312 are provided at positions corresponding to the first plasma region P1 and the second plasma region P2, respectively, which will be described later. Specifically, the first guide wall 311 is provided at or near the upper end of the spiral conveying path 31A, and the second guide wall 312 is provided at a location on the radially opposite side of the spiral conveying path 31A from the first guide wall 311 in a plan view as shown in FIG. 10.

Each of the first guide wall 311 and the second guide wall 312 has a guide surface which is a side surface rising upward from the spiral conveying path 31A. The second guide wall 312 is disposed at a position radially inwardly spaced from the inner surface 14 of the container 10 so that a gap is formed between the second guide wall 312 and the inner surface 14 of the container 10. The guide surface of the second guide wall 312 has a shape capable of guiding a portion of the powder F conveyed upward along the spiral conveying path 31A radially inward from the spiral conveying path 31A and allowing it to fall from the spiral conveying path 31A toward the bottom surface 13 through the second powder falling space S2. The guide surface of the first guide wall 311 has a shape that allows the powder F, which passes through the gap between the second guide wall 312 and the inner surface 14 of the container 10 and is transported upward along the spiral transport path 31A, to be guided radially inward from the spiral transport path 31A and allowed to fall from the spiral transport path 31A toward the bottom surface 13 through the first powder drop space S1.

The vibration generating unit 32 in the first modified example is the same as the vibration generating unit 32 shown in Figs. 1 and 2. That is, the vibration generating unit 32 operates to vibrate the container 10 to transport the powder F arranged on the bottom surface 13 upward along the spiral transport path 31A. The vacuum chamber 40 forms an internal space that houses the container 10. A pipe (not shown) for vacuum drawing is connected to the side of the chamber body 41. The inert gas supply unit 70 is for supplying an inert gas into the vacuum chamber 40 when the film formation process is performed. For example, argon gas is used as the inert gas.

Next, in the first modified example, a method of performing a film formation process on the surface of the powder F by sputtering will be described. First, a predetermined amount of powder F is placed on the bottom surface 13 of the container 10, and after the vacuum chamber 40 is evacuated, an inert gas (e.g., argon gas) is supplied into the vacuum chamber 40. In this state, the AC power supply PS applies alternately positive and negative voltages to the targets 54 of the two rotary cathodes 53, thereby generating a first plasma region P1 near these targets 54 and ionizing the inert gas. Similarly, the AC power supply applies alternately positive and negative voltages to the targets 54 of the remaining two rotary cathodes 53, thereby generating a second plasma region P2 near these targets 54 and ionizing the inert gas. The ionized inert gas collides with the target 54, and the particles E (e.g., atoms or molecules) that constitute the target 54 are knocked out by the kinetic energy.

The numerous particles E that are knocked out from the targets 54 of the four rotary cathodes 53 move in various directions within the container 10. Specifically, some of the particles E that are knocked out from the targets 54 move downward in the powder drop space S and adhere to the surface of the powder F on the bottom surface 13. Another part of the particles E that are knocked out from the targets 54 move toward the spiral transport path 31A and adhere to the surface of the powder F on the spiral transport path 31A. This allows a film formation process to be performed on the surface of the powder F on the bottom surface 13, and also on the surface of the powder F on the spiral transport path 31A.

In the first modified example, each target 54 is arranged so that the central axis of the cylinder constituting the target 54 faces the vertical direction, and at least a part of the target 54 faces the spiral transport path 31A in the horizontal direction (the radial direction of the container 10). In the specific example shown in FIG. 9, each target 54 faces each of the multiple parts (multiple transport parts) of the spiral transport path 31A in the radial direction. The multiple transport parts are arranged vertically at intervals along the vertical direction, which is the longitudinal direction of the target 54. Therefore, the particles E knocked out from the target 54 are efficiently supplied to each of the multiple transport parts of the spiral transport path 31A and adhere to the surface of the powder F on the transport part. This allows the film formation process to be performed efficiently.

In addition, in the first modified example, the multiple rotary cathodes 53 and the inert gas supply unit 70 are an example of a film formation source that makes the film formation material in a film-formable state in which a film can be formed on the surface of the powder F. Specifically, the multiple rotary cathodes 53 and the inert gas supply unit 70 are configured to make the film formation material in the film-formable state on the surface of the target 54 located in the container 10, and to supply the film formation material E in the film-formable state to the powder F on the bottom surface 13 through the powder drop space S and to supply it to the powder F on the spiral transport path 31A. The material that constitutes the target 54 is an example of a film formation material, and the particles E knocked out from the target 54 (particles E flying out from the target 54) are an example of a film formation material in a film-formable state.

Figure 11 is a side view of a powder deposition apparatus 1 according to Modification 2 of the first embodiment, partially in cross section. Figure 12 is a cross-sectional view taken along line XII-XII in Figure 11. As shown in Figures 11 and 12, the powder deposition apparatus 1 according to Modification 2 includes an apparatus main body, a vacuum chamber 40, a sputtering unit 50, an inert gas supply section 70, and a support table 90 that supports these. The apparatus main body includes a container 10 and a powder moving mechanism 30.

The configurations of the container 10, powder moving mechanism 30, vacuum chamber 40, inert gas supply unit 70, and support table 90 of the powder deposition apparatus 1 according to the modified example 2 are similar to those of the powder deposition apparatus 1 shown in Figures 1 to 5, so detailed descriptions of these will be omitted. Below, the differences between the powder deposition apparatus 1 according to the modified example 2 and the powder deposition apparatus 1 shown in Figures 1 to 5 will be mainly described.

As shown in Figures 11 and 12, the sputtering unit 50 in variant 2 includes multiple rotary cathodes 53 (specifically, two rotary cathodes 53). Each of the multiple rotary cathodes 53 has a configuration similar to that of the rotary cathode 53 in variant 1. That is, each of the multiple rotary cathodes 53 includes a cylindrical target 54 and a magnet 56 disposed within the target 54.

In the second modification, each target 54 is supported by a support member (not shown) so that the central axis of the cylinder that constitutes the target 54 faces horizontally and can rotate around the central axis. The magnet 56 has a shape that extends within the target 54 along the direction of the central axis of the target 54.

The two rotary cathodes 53 are arranged above the bottom surface 13 of the container 10 and spaced apart from each other in the horizontal direction. Specifically, the two rotary cathodes 53 are arranged directly above the container 10 so that they face the same direction and are positioned at the same height.

The two rotary cathodes 53 are connected to an AC power supply PS as shown in FIG. 11. When a film formation process is performed, the AC power supply PS alternately applies positive and negative voltages for sputtering to the targets 54 of the two rotary cathodes 53. This causes a discharge between the two rotary cathodes 53 to form plasma. In each of the two rotary cathodes 53, the magnet 56 is disposed at the bottom of the cylinder constituting the target 54 so that a plasma region P is formed in a wide area directly below the rotary cathodes 53. In each of the two rotary cathodes 53, the relative position of the magnet 56 with respect to the container 10 and the target 54 is set so that a plasma region P is formed between the rotary cathodes 53 and the bottom surface 13 of the container 10.

As shown in FIG. 12, the powder moving mechanism 30 in this modified example 2 has an upper conveying path 31 and a vibration generating unit 32 (vibration generating device), and the upper conveying path 31 includes a spiral conveying path 31A and an inner guide path 31B, similar to the upper conveying path 31 shown in FIG. 2 and FIG. 4.

Next, in Modification 2, a method of performing a film formation process on the surface of powder F by sputtering will be described. First, a predetermined amount of powder F is placed on the bottom surface 13 of the container 10, and after the vacuum chamber 40 is evacuated, an inert gas (e.g., argon gas) is supplied into the vacuum chamber 40. In this state, the AC power supply PS applies alternating positive and negative voltages to the targets 54 of the two rotary cathodes 53, generating a plasma region P near these targets 54 and ionizing the inert gas. The ionized inert gas collides with the target 54, and the particles E (e.g., atoms or molecules) that make up the target 54 are knocked out by the kinetic energy.

A part of the particles E knocked out from each of the targets 54 of the two rotary cathodes 53 moves downward in the powder drop space S and adheres to the surface of the powder F on the bottom surface 13. In this embodiment, as shown in FIG. 11, there is no obstruction between at least a part of the spiral transport path 31A and the lower surface of each target 54, which is the position where the film-forming material is ready for film formation. Therefore, another part of the particles E knocked out from each target 54 moves toward the at least a part of the spiral transport path 31A in the powder drop space S and adheres to the surface of the powder F thereon. This allows the film formation process to be performed on the surface of the powder F on the bottom surface 13 and the surface of the powder F on the at least a part of the spiral transport path 31A.

In addition, in the second modified example, the multiple rotary cathodes 53 and the inert gas supply unit 70 are an example of a film-forming source that makes the film-forming material in a film-forming state capable of forming a film on the surface of the powder F. Specifically, the multiple rotary cathodes 53 and the inert gas supply unit 70 make the film-forming material in the film-forming state on the lower surface of the target 54, and supply the film-forming material E in the film-forming state to the powder F on the bottom surface 13 through the powder drop space S and to the powder F on the spiral transport path 31A. The material constituting the target 54 is an example of a film-forming material, and the particles E knocked out from the target 54 (particles E flying out from the target 54) are an example of a film-forming material in a film-forming state. In addition, the position of the lower surface of the target 54 is an example of a position that is above the container 10 and faces the bottom surface 13 in the vertical direction. The lower surface of the target 54 may be located inside the container 10. In this case, the multiple rotary cathodes 53 and the inert gas supply unit 70 as the film-forming source are configured to bring the film-forming material to the film-forming state on the lower surface of the target 54 located inside the container 10, and to supply the film-forming material in the film-forming state to the powder on the bottom surface 13.

Figure 13 is a side view of a powder deposition apparatus 1 according to Modification 3 of the first embodiment, partially in cross section. Figure 14 is a cross-sectional view taken along line XIV-XIV in Figure 13. As shown in Figures 13 and 14, the powder deposition apparatus 1 according to Modification 3 includes an apparatus main body, a vacuum chamber 40, a sputtering unit 50, an inert gas supply unit 70, and a support table 90 that supports these.

In this modified example 3, the device main body includes a container 10 and a vibration generating unit 32 (vibration generating device), the container 10 includes a bottom surface 13, an inner surface 14, and an upper conveying path 31, and the upper conveying path 31 includes a spiral conveying path 31A and an inner guide path 31B. Also, in this modified example 3, the powder moving mechanism includes the upper conveying path 31 of the container 10 and the vibration generating unit 32. The upper conveying path 31 is formed in an area inside the container 10 other than the powder falling space S. In this modified example 3, the upper conveying path 31 constitutes a part of the container 10, specifically, constitutes a part of the inner surface of the container 10.

In Modification 3 shown in Figures 13 and 14, the configuration of the container 10 differs from Modification 2, but the other configurations are the same as Modification 2. Below, the differences between the powder film forming apparatus 1 of Modification 3 and the powder film forming apparatus 1 of Modification 2 will be mainly described, and the description of the configurations that are the same as those of Modification 2 will be omitted.

As shown in FIG. 13, the container 10 in the third modified example is configured as a container (a stepped bowl) having a shape in which the bottom surface 13, the inner surface 14, and the spiral conveying path 31A are arranged in a stepped manner in a cross section when the container 10 is cut along a vertical plane including the central axis A of the container 10.

The spiral conveying path 31A extends upward in a spiral shape from the bottom surface 13. The spiral conveying path 31A has a shape that, in a plan view, gradually moves away from the center of the container 10 (the central axis A of the container 10) as it extends upward. In other words, the spiral conveying path 31A has a shape that is positioned radially outward as it extends upward. The upper region 31A2 of the spiral conveying path 31A is positioned radially outward relative to the lower region 31A1 of the spiral conveying path 31A. Specifically, the spiral conveying path 31A has a shape such that the lower region 31A1 of the spiral conveying path 31A and the upper region 31A2 of the spiral conveying path 31A do not overlap in a plan view as shown in FIG. 14.

Compared to the spiral conveying path 31A in variant 2 (see Figures 11 and 12), which has a spiral shape with a constant distance from the center (central axis A) of the container 10, for example, the spiral conveying path 31A in variant 3 allows the film-forming material that has reached a film-forming state to be efficiently supplied not only to the powder F in the upper region 31A2 of the spiral conveying path 31A, but also to the powder F in the lower region 31A1 of the spiral conveying path 31A.

Figure 15 is a side view of the powder deposition apparatus 1 according to the fourth modified example of the first embodiment, partially in cross section. Figure 15 differs from Figure 1 in that the sealing mechanism, which will be described later, is specifically illustrated. Below, the configuration of the powder deposition apparatus 1 shown in Figure 15 that is related to the sealing mechanism will be mainly described, and the other configuration of the powder deposition apparatus 1 shown in Figure 15 will be assigned the same reference numerals as in Figure 1 and will not be described.

In the powder deposition apparatus 1 shown in FIG. 15, the container 10 is disposed in the vacuum chamber 40, the generator body 321 of the vibration generating unit 32 (vibration generating device) is disposed outside the vacuum chamber 40 (e.g., in the atmosphere) below the container 10, and the shaft 322 of the vibration generating unit 32 connects the generator body 321 and the container 10. As described above, the chamber body 41 of the vacuum chamber 40 is a container having a bottom, and the bottom includes a partition member 81 as shown in FIG. 15. This partition member 81 is interposed between the generator body 321 of the vibration generating unit 32 and the container 10, and has, for example, a plate shape. A through hole having an inner diameter slightly larger than the outer diameter of the shaft 322 is formed in the partition member 81, and the shaft 322 is inserted into this through hole.

The powder deposition apparatus 1 shown in FIG. 15 is equipped with an O-ring 80 as a sealing mechanism for maintaining the degree of vacuum within the vacuum chamber 40. The O-ring 80 is a member having a circular ring shape formed from a material having rubber elasticity, for example. The O-ring 80 has a circular ring shape surrounding the shaft 322, and is disposed between the shaft 322 and a partition member 81. This maintains the degree of vacuum within the vacuum chamber 40.

Figure 16 is a side view of the powder deposition apparatus 1 according to the fifth modified example of the first embodiment, partially in cross section. Figure 16 differs from Figure 13 in that the sealing mechanism is specifically illustrated. Below, the configuration related to the sealing mechanism among the configuration of the powder deposition apparatus 1 shown in Figure 16 will be mainly described, and the other configuration of the powder deposition apparatus 1 shown in Figure 16 will be assigned the same reference numerals as in Figure 13 and will not be described.

In the powder deposition apparatus 1 shown in FIG. 16, similarly to the powder deposition apparatus 1 shown in FIG. 15, the container 10 is placed in the vacuum chamber 40, the generator body 321 of the vibration generating unit 32 is placed outside the vacuum chamber 40 (e.g., in the atmosphere) below the container 10, and the shaft 322 of the vibration generating unit 32 connects the generator body 321 and the container 10. The bottom of the chamber body 41 of the vacuum chamber 40 includes a partition member 81 as shown in FIG. 16. A through hole having an inner diameter slightly larger than the outer diameter of the shaft 322 is formed in this partition member 81, and the shaft 322 is inserted into this through hole.

The powder deposition apparatus 1 shown in FIG. 16 is equipped with an O-ring 80 similar to that shown in FIG. 15 as a sealing mechanism for maintaining the degree of vacuum within the vacuum chamber 40. The O-ring 80 has an annular shape surrounding the shaft 322, and is disposed between the shaft 322 and a partition member 81. This allows the degree of vacuum within the vacuum chamber 40 to be maintained.

The reason why the generating unit body 321 of the vibration generating unit 32 is arranged outside the vacuum chamber 40, rather than inside the vacuum chamber 40, will be explained. The generating unit body 321 includes a vibrator that generates vibrations. Examples of the vibrator include a type that uses an electromagnet and a type that uses a piezoelectric element. The vibrator includes various parts such as electronic components. Such a generating unit body 321 is a source of gas generation. Therefore, when the generating unit body 321 is arranged in the vacuum chamber 40, gas components other than the process gas (e.g., the inert gas) may be mixed into the film formed on the surface of the powder F, and the film quality, such as the conductivity, may be reduced. In addition, if the gas generated due to the generating unit body 321 contains a lot of moisture, the crystallinity of the film may be damaged and the film quality may be reduced. In addition, when the generating unit body 321 is arranged in the vacuum chamber 40, the deterioration of the electronic components may be accelerated. In addition, since powder F is present in the vacuum chamber 40, if the generating unit body 321 is placed in the vacuum chamber 40, the powder F may get mixed into the generating unit body 321, leading to a breakdown of the generating unit body 321. Therefore, it is preferable that the container 10 is placed in the vacuum chamber 40 and the generating unit body 321 of the vibration generating unit 32 is placed outside the vacuum chamber 40.

The sealing mechanism may be, for example, a bellows. The bellows is a cylindrical, bellows-like member. The bellows is, for example, disposed between the bottom surface of the container 10 and the top surface of the partition member 81 so as to surround the shaft 322. The periphery of the top end of the bellows is fixed to the bottom surface of the container 10, and the periphery of the bottom end of the bellows is fixed to the top surface of the partition member 81 so as to maintain the vacuum level of the vacuum chamber 40. The sealing mechanism may also be, for example, an oil seal. The oil seal has an inner periphery (lip portion) that contacts the shaft 322, and an outer periphery (fitting portion) that contacts the partition member 81.

However, the sealing mechanism is preferably an O-ring 80 in terms of durability as described below. The vibration generating unit 32 vibrates the container 10 in an oblique direction including a component in the direction of the central axis A of the container 10 and a component in the circumferential direction around the central axis A in order to transport the powder F arranged on the bottom surface 13 of the container 10 upward along the spiral transport path 31A. That is, the container 10 is torsionally vibrated in association with the vibration of the generating unit body 321 of the vibration generating unit 32. When the container 10 is vibrated in such an oblique direction, a force in a direction along the oblique direction acts on the sealing mechanism, and a torsional load is applied. The O-ring 80 is more durable against the torsional load than a bellows and an oil seal, and therefore the effect of maintaining the vacuum degree of the vacuum chamber 40 can be ensured for a longer period of time than a bellows and an oil seal.

The powder deposition device 1 may have only a single O-ring 80 as a sealing mechanism as shown in each of FIG. 15 and FIG. 16, or may have a plurality of (for example, two) O-rings 80 arranged at intervals in the axial direction of the shaft 322 as a sealing mechanism. The O-ring 80 may be arranged so that a part of the O-ring 80 fits into an annular groove (not shown) formed along the circumferential direction on the outer circumferential surface of the shaft 322. The O-ring 80 may be arranged so that a part of the O-ring 80 fits into an annular groove (not shown) formed along the circumferential direction on the inner circumferential surface of the partition member 81 surrounding the shaft 322. In the above specific example, the partition member 81 is a member that constitutes a part of the vacuum chamber 40, but may also be a member that constitutes a part of the support table 90.

Specific illustrations of the sealing mechanism are omitted in Figures 1, 9, 11, and 13, but each of the powder deposition apparatuses 1 shown in Figures 1, 9, 11, and 13 has a sealing mechanism for maintaining the vacuum level in the vacuum chamber 40, similar to the powder deposition apparatus 1 shown in Figures 15 and 16. Also, as shown in Figures 1, 9, 11, and 13, in each of the powder deposition apparatuses 1, the container 10 is disposed in the vacuum chamber 40, and the vibration generating unit main body 321 of the vibration generating unit 32 is disposed outside the vacuum chamber 40 (e.g., in the atmosphere).

Next, the shape of the container 10 will be further described. Each container 10 of the powder deposition apparatus 1 shown in Figures 1 to 12 and 15 is a cylindrical container having a bottom. On the other hand, each container 10 of the powder deposition apparatus 1 shown in Figures 13, 14 and 16 is a stepped container in which the bottom surface 13, the inner surface 14 and the spiral transport path 31A are arranged in a staircase shape in the cross section shown in Figures 13 and 16. When the total length of the spiral transport path 31A in the cylindrical container 10 is approximately the same as the total length of the spiral transport path 31A in the stepped container 10, the cylindrical container 10 can have a smaller outer diameter than the stepped container 10, and as a result, the vacuum chamber 40 can be made compact.

The cylindrical container has an inner surface 14, for example, as shown in Figures 1, 2, 5, and 15, and the stepped container 10 has an inner surface 14, for example, as shown in Figures 10, 13, 14, and 16. The inner surface 14 is a surface that rises vertically upward from the outer periphery of the bottom surface 13. In the case of the stepped container 10, the inner surface 14 is not hidden behind the spiral transport path 31A in plan view, as can be seen, for example, from the plan view shown in Figure 14. Therefore, since the film-forming material E that has become film-formable in the film-forming source can easily reach many areas of the inner surface 14 of the container 10, a film is formed on many areas of the inner surface 14. On the other hand, in the case of the cylindrical container 10, many areas of the inner surface 14 are hidden behind the spiral transport path 31A in plan view, as can be seen, for example, from the perspective view of Figure 2 and the plan view of Figure 4. Therefore, the film-forming material E that has become film-formable in the film-forming source is unlikely to reach many areas of the inner surface 14. Therefore, in the cylindrical container 10, the ratio of the area on which a film is formed to the entire area of the inner surface 14 is significantly smaller than that of the stepped container 10. Since the inner surface 14 of the container 10 is an area on which film formation is not required, forming a film on the inner surface 14 is wasteful and undesirable. Therefore, from this perspective, the cylindrical container 10 is preferable to the stepped container 10. In this way, the cylindrical container 10 can suppress film formation in areas on which film formation is not required compared to the stepped container 10, and can efficiently form a film on the powder F on the spiral conveying path 31A, the powder F on the inner guide path 31B, and the powder F on the bottom surface 13.

Next, the opening and closing structure of the vacuum chamber 40 will be further described. When the target (target 52 in each of FIGS. 1 and 15, and target 54 of the rotary cathode 53 in each of FIGS. 11, 13, and 16) is placed above the container 10, the vacuum chamber 40 can be configured so that the lid 42 is attached to the upper part of the chamber body 41 via the hinge 43 as shown in FIG. 3 so as to be openable and closable. On the other hand, when the rotary cathode 53 is placed vertically and the target 54 of the rotary cathode 53 is placed inside the container 10 as shown in FIG. 9, the vacuum chamber 40 is configured so that the top plate is removable from the chamber body, which is the part below the top plate. The rotary cathode 53 is fixed to the top plate. By attaching the top plate to the chamber body, the rotary cathode 53 is placed at a predetermined position. Also, in FIG. 9, the top plate does not have to be integral with the chamber body and cannot be removed. In this case, a through hole is formed in the top plate, through which the upper part of the rotary cathode 53 is inserted, and an adapter flange is attached to the upper part of the rotary cathode 53, which is located above the top plate. This adapter flange includes, for example, a power source and its wiring. The adapter flange and the rotary cathode 53 supported by it can be removed from the top plate by lifting them upward. The area between the adapter flange and the top plate is preferably sealed with a sealing member (for example, an O-ring).

Next, the inner guide path 31B will be further described. The inner guide path 31B shown in each of Figures 2, 4, 8, 12, and 14 has a curved shape (for example, a circular arc shape) in a plan view as described above, and is smoothly continuous with the spiral conveying path 31A. Therefore, when the container 10 is torsionally vibrated with the vibration of the generating unit body 321 of the vibration generating unit 32, the powder F that reaches the upper end of the spiral conveying path 31A is smoothly conveyed into the inner guide path 31B, and the conveyed powder F is smoothly guided to the tip of the inner guide path 31B. If a linear guide path (linear chute) is connected to the upper part of the spiral conveying path 31A and the guide path is arranged so that the extension direction of the guide path is perpendicular to the tangential direction of the spiral conveying path 31A at the upper part of the spiral conveying path 31A in a plan view, the following problem occurs. In this case, the powder F that reaches the top of the spiral conveying path 31A is conveyed from the spiral conveying path 31A to the guide path perpendicular to it, but the direction of movement of the powder F immediately after being conveyed is along the tangent direction of the spiral conveying path 31A, not the direction of the guide path perpendicular to it. Therefore, the powder F conveyed to the linear guide path will stagnate near the connection between the spiral conveying path 31A and the guide path, and some of the powder F on the guide path will overflow the guide path and fall downward without reaching the tip of the guide path. As a result, it becomes difficult to uniformly mix the powder F in the container 10.

Specifically, when the container 10 is torsionally vibrated as described above, the powder F on the spiral conveying path 31A is given kinetic energy in a direction along the circumferential direction of the spiral conveying path 31A (for example, a tangential direction of the spiral conveying path 31A). Since the inner guide path 31B has a curved shape that smoothly continues to the spiral conveying path 31A, the powder F conveyed to the inner guide path 31B can move on the inner guide path 31B toward the tip of the inner guide path 31B by the kinetic energy given from the container 10. As described above with reference to FIG. 2, the inner guide path 31B has an upper surface on which the powder F is placed and a pair of side surfaces that rise upward from a pair of edges located on both sides of the upper surface, but the inner side surface of the pair of side surfaces can be omitted.

In addition, the tip of the inner guide path 31B is located above and away from the bottom surface 13 of the container 10. Therefore, the powder F guided to the tip of the inner guide path 31B falls freely toward the bottom surface 13 of the container 10, suppressing the agglomeration of the powder F within the container 10. The powder F in the vacuum of the vacuum chamber 40 tends to agglomerate more easily than when it is in the atmosphere, but by free falling from the tip of the inner guide path 31B to the bottom surface 13 of the container 10 as described above, the agglomeration of the powder F is suppressed. This allows the powder F to be stirred more uniformly, resulting in a more uniform film-forming state of the powder F.

The powder F is also formed into a film while moving on the inner guide path 31B. Since the inner guide path 31B is relatively close to the film-forming source, the powder F on the inner guide path 31B is efficiently formed into a film. If the inner guide path is formed so as to continue from the upper end of the spiral conveying path 31A to the bottom surface 13 of the container 10, the degree of inclination of the inner guide path with respect to the horizontal plane becomes large. The speed of the powder F moving to the bottom surface 13 of the container 10 while being guided by such an inner guide path is inevitably likely to increase. In this case, the powder F is sparsely present on the inner guide path, and the proportion of the exposed portion of the upper surface of the inner guide path that is not covered by the powder F tends to increase. In this way, the film-forming material E that has become film-formable in the film-forming source reaches the exposed portion of the upper surface of the inner guide path and forms a film. Since the upper surface of the inner guide path is an area that does not need to be film-formed, it is wasteful and undesirable to form a film on the upper surface of the inner guide path. Also, the powder F moving toward the bottom surface at a high speed along the inner guide path is less likely to be efficiently filmed. Therefore, in the powder film forming device 1 according to this embodiment, the degree of inclination of the inner guide path 31B with respect to the horizontal plane is set to be small so that the increase in the moving speed of the powder F guided by the inner guide path 31B can be suppressed to be relatively small. This suppresses the powder F from being sparsely present on the inner guide path 31B, and the powder F moving on the inner guide path 31B at a relatively slow speed is efficiently filmed. In addition, by reducing the degree of inclination of the inner guide path 31B with respect to the horizontal plane, the vertical distance between the tip of the inner guide path 31B and the bottom surface 13 of the container 10 can be increased. This makes it easier to increase the falling speed of the powder F that has fallen freely from the tip of the inner guide path 31B before it reaches the bottom surface 13 of the container 10. This makes it possible to further enhance the stirring effect of the powder F due to the free fall of the powder F.

The tip of the inner guide path 31B is preferably located, for example, above the center in the vertical direction on the inner surface 14 of the container 10. In addition, the vertical distance between the tip of the inner guide path 31B and the bottom surface 13 of the container 10 is preferably greater than half the distance between the upper end of the container 10 and the bottom surface 13 of the container 10.

[Other Modifications]
Although the powder film forming apparatus 1 according to the embodiment of the present disclosure has been described above, the present disclosure is not limited to these embodiments and may be modified as follows, for example.

(1) The powder moving mechanism of the device body does not have to have a vibration generating unit 32. For example, the powder moving mechanism may be equipped with a mechanism that transports the powder from the bottom surface upward by a driving source such as a motor. An example of such a mechanism is a belt conveyor. The inner guide path of the upper transport path can be omitted. In the above embodiment, the powder transported upward by the upper transport path falls freely, but this is not limited to this form. For example, the powder transported upward by the upper transport path may fall toward the bottom surface 13 along a guide path (not shown) that extends from that position toward the bottom surface 13 and guides the fall of the powder.

(2) The container is not limited to a cylindrical shape, and may be another shape, such as a rectangular parallelepiped shape. In addition, the bottom surface of the container does not have to include an inclined surface.

(3) If the film formation process is performed using a method such as CVD in an atmosphere other than a vacuum atmosphere, the vacuum chamber can be omitted.

(4) The method of film formation is not limited to sputtering, arc ion plating, and plasma CVD.

(5) In the third embodiment, the inert gas supply unit 70 can be omitted.

(6) In each embodiment, the powder drop space S does not necessarily have to be located in the center of the container 10, but may be located at a position horizontally offset from the center of the container 10.

(7) The spiral conveying path 31A as shown in Figures 13 and 14, i.e., a spiral conveying path having a shape that gradually moves away from the center of the container in a plan view as it moves upward, can be used in an apparatus that applies a film formation process to the surface of powder by arc ion plating, such as the powder coating apparatus of the second embodiment, and can also be used in an apparatus that applies a film formation process to the surface of powder by plasma CVD, such as the powder coating apparatus of the third embodiment.

(8) In each of the first to third modified examples of the first embodiment, the sputtering unit 50 includes multiple rotary cathodes 53, but is not limited to this configuration. The sputtering unit 50 only needs to include at least one rotary cathode 53. When the sputtering unit 50 includes only one rotary cathode 53, the rotary cathode 53 is connected to a DC power supply.

1 Powder film forming apparatus 10 Container 13 Bottom surface of container 14 Inner surface of container 30 Powder moving mechanism 31 Upper conveying path 31A Spiral conveying path 31B Inner guide path 32 Vibration generating unit 40 Vacuum chamber 41 Chamber body 42 Lid 50 Sputtering unit 50A Arc ion plating unit 52 Target 53 Rotary cathode 54 Target 60 Plasma source 62 Pipe of raw material gas supply unit 63 Opening 70 Inert gas supply unit A Central axis of container E Film forming material F ready for film formation Powder S Powder falling space

Claims (22)

A powder film forming apparatus for performing a film forming process on a surface of a powder, comprising:
an apparatus main body including a container having a bottom surface on which powder can be placed, the container having a powder drop space formed therein, the powder drop space being a space continuing upward from the bottom surface, the apparatus main body being configured such that an upper transport path is formed for transporting powder placed on the bottom surface of the container upward within an area of the container other than the powder drop space, and the powder transported upward along the upper transport path can be dropped onto the bottom surface through the powder drop space;
a film-forming source for making the film-forming material into a film-forming state capable of forming a film on the surface of the powder;
the film formation source is configured to bring the film formation material into the film-formable state at least one of a position above the container and facing the bottom surface in the vertical direction and inside the container, and to supply the film formation material in the film-formable state to the bottom surface through the powder falling space ;
the upper conveying path includes a spiral conveying path extending upward from the bottom surface in a spiral shape, and an inner guide path extending from the upper end so as to guide the powder conveyed to the upper end of the spiral conveying path to a region radially inward of the container relative to the upper end,
The inner guideway has a curved shape in a plan view,
a tip end of the inner guide path is located above the center of the bottom surface of the container across the powder falling space,
The powder deposition apparatus, wherein the apparatus main body further includes a vibration generating unit, and the vibration generating unit operates to vibrate the container in the vertical direction about its central axis and in the circumferential direction around the central axis, thereby transporting the powder placed on the bottom surface upward along the spiral transport path, guiding it along the curved inner guide path, and causing it to fall from the tip of the inner guide path . A powder film forming apparatus for performing a film forming process on a surface of a powder, comprising:
an apparatus main body including a container having a bottom surface on which powder can be placed, the container having a powder drop space formed therein, the powder drop space being a space continuing upward from the bottom surface, the apparatus main body being configured such that an upper transport path is formed for transporting powder placed on the bottom surface of the container upward within an area of the container other than the powder drop space, and the powder transported upward along the upper transport path can be dropped onto the bottom surface through the powder drop space;
a film-forming source for making the film-forming material into a film-forming state capable of forming a film on the surface of the powder;
the film formation source is configured to bring the film formation material into the film-formable state at least one of a position above the container and facing the bottom surface in the vertical direction and inside the container, and to supply the film formation material in the film-formable state to the bottom surface through the powder falling space;
the upper conveying path includes a spiral conveying path extending spirally upward from the bottom surface, a first guide wall provided at an upper portion of the spiral conveying path, and a second guide wall provided at a portion of the spiral conveying path upstream of the first guide wall in the conveying direction,
A powder deposition apparatus, wherein each of the first guide wall and the second guide wall is configured to guide powder transported upward along the spiral transport path radially inward of the container further than the spiral transport path so as to cause the powder to fall from the spiral transport path toward the bottom surface. The powder film forming apparatus according to claim 1 , wherein the film forming source is configured to supply the film forming material in the film-forming state also to at least a portion of the upper transport path. The powder deposition apparatus according to claim 1 , wherein the powder falling space is a space located radially inside the container relative to the spiral transport path. The powder deposition apparatus according to claim 1 , wherein the inner guide path includes a portion that slopes downward toward a tip of the inner guide path. The bottom surface of the container includes an inclined surface that slopes downward from a center portion of the bottom surface toward an outer side in a radial direction of the container ,
The powder deposition apparatus according to claim 1 or 5 , wherein the inner guide path is disposed so that a drop point of at least a part of the powder dropping from a tip of the inner guide path is the central part of the bottom surface. The powder deposition apparatus according to claim 1 , wherein the spiral transport path has a shape that, in a plan view, gradually moves away from a center of the container as it goes upward. The powder film forming apparatus is an apparatus for performing a film forming process on a surface of a powder by sputtering,
the deposition source includes a cathode for the sputtering;
The powder deposition apparatus according to claim 1 , wherein the cathode is disposed at a position vertically opposed to the bottom surface across the powder falling space. The powder film forming apparatus is an apparatus for performing a film forming process on a surface of a powder by sputtering,
The powder deposition apparatus according to claim 1 , wherein the deposition source includes at least one rotary cathode for the sputtering. The powder film forming apparatus is an apparatus for performing a film forming process on a surface of a powder by sputtering,
the deposition source includes at least one rotary cathode for the sputtering;
the at least one rotary cathode includes a cylindrical target;
The powder deposition apparatus according to any one of claims 1 to 7, wherein the target is arranged in such a manner that a central axis of the target faces in a vertical direction and at least a portion of the target faces the spiral transport path in a horizontal direction. The powder film forming apparatus is an apparatus for performing a film forming process on a surface of a powder by arc ion plating,
the deposition source includes a cathode for the arc ion plating;
The powder deposition apparatus according to claim 1 , wherein the cathode is disposed at a position vertically opposed to the bottom surface across the powder falling space. 12. The powder deposition apparatus according to claim 8, wherein an area of the bottom surface overlapping with the powder falling space in a plan view has a size such that the cathode is included within the area in a plan view. The powder film forming apparatus is an apparatus for performing a film forming process on a surface of a powder by plasma CVD,
the film formation source includes a plasma source for bringing a raw material gas into the film formation state,
The powder deposition apparatus according to claim 1 , wherein the plasma source is disposed at a position vertically opposed to the bottom surface across the powder falling space. The powder deposition apparatus according to claim 13 , further comprising a source gas supply unit that supplies the source gas to a region affected by the plasma source. 15. The powder deposition apparatus according to claim 14 , wherein the plasma source has an opening formed in a lower portion of the plasma source and provided for discharging the plasma generated inside the plasma source to the outside of the plasma source. 16. The powder deposition apparatus according to claim 15, wherein the raw material gas supply unit has a pipe arranged in a ring shape so as to surround the opening of the plasma source in a plan view, and is configured so as to be able to supply the raw material gas below the plasma source from a gas supply hole formed in the pipe . 17. The powder deposition apparatus according to claim 15 , wherein an area of the bottom surface overlapping with the powder falling space in a plan view has a size such that the opening of the plasma source is included within the area in a plan view. The powder deposition apparatus according to any one of claims 13 to 17 , further comprising an inert gas supply unit that supplies an inert gas into the container so that the raw material gas in the film-forming state is guided toward the bottom surface in the powder falling space. a vacuum chamber for housing the container;
The container has an upwardly opening shape,
The powder film forming apparatus according to claim 1 , wherein the film forming material is brought into the film-forming state at least one of above the container and inside the container in the vacuum chamber. The vacuum chamber comprises:
a chamber body that defines an internal space for accommodating the container and is open upward;
The powder deposition apparatus according to claim 19 , further comprising: a lid portion attached to an upper portion of the chamber body in an openable and closable manner. a vacuum chamber for housing the container;
The vibration generating unit includes a generating unit body that generates vibrations, and a shaft that connects the generating unit body and the container,
The powder deposition apparatus according to claim 1 , wherein the generation unit body is disposed outside the vacuum chamber. A powder film-forming method for performing a film-forming process on a surface of a powder by using the powder film-forming apparatus according to any one of claims 1 to 21 , comprising:
placing a powder in the container;
conveying the powder in the container along the upward conveying path, and allowing the powder conveyed upward to fall onto the bottom surface through the powder falling space;
and forming a film on a surface of powder using the film-forming material that has become capable of forming a film.

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