JP7519702B2 - Carbon fiber coating method and device - Google Patents

Description

The present invention relates to a method and apparatus for forming a coating on carbon fibers, and more specifically, to a method and apparatus for forming a coating on carbon fibers in which a coating material that has been positively ionized in a vacuum chamber is attached to the surface of the carbon fibers to which a negative voltage has been applied to form a coating.

Conventionally, a method for producing a metal composite material using carbon fiber as a reinforcing material is known in which a metal coating is formed on the surface of carbon fiber by ion plating, the metal-coated carbon fiber is mixed into a base metal, and the carbon fiber is dispersed and integrated into the base metal by metal melting or sintering to obtain a metal composite material (see Patent Document 1 below).

However, in the manufacturing method of metal composite material described in Patent Document 1, when forming a metal coating on the surface of carbon fiber, long or short carbon fibers are placed in a rotating wire mesh container and ion plating is performed while rotating and stirring the carbon fibers. As a result, the orientation of the obtained metal-coated carbon fibers is random. For example, in order to obtain a metal composite material in which the carbon fibers are oriented in a uniform manner, a separate process of aligning the orientation of these metal-coated carbon fibers is required. Furthermore, in order to form a uniform coating, there is a limit to the amount of carbon fibers that can be placed in the rotating wire mesh container, which makes it difficult to mass-produce metal-coated carbon fibers.

Japanese Unexamined Patent Publication No. 51-61404

The present invention was made in consideration of the above-mentioned drawbacks of conventional carbon fiber coating methods, and aims to provide a method and apparatus for forming a coating on carbon fibers that can form an even coating on the surface of each carbon fiber when a large number of carbon fibers are aligned in a sheet shape, and that can mass-produce carbon fiber sheets in which a coating is evenly formed on the surface of each carbon fiber.

The method for forming a coating on carbon fibers according to the present invention is a method for forming a coating on carbon fibers by adhering a positively ionized coating material to the surface of carbon fibers to which a negative voltage has been applied in a vacuum chamber to form a coating, characterized in that both ends of a carbon fiber sheet obtained by arranging a large number of carbon fibers into a sheet shape are held by holders, and a coating is formed on each of the carbon fibers while micro-vibrating each of the carbon fibers via the holder by a vibrator , and a spread fiber sheet is used as the carbon fiber sheet, which is obtained by passing an air flow through a carbon fiber bundle obtained by previously arranging a large number of carbon fibers into a sheet shape .

The carbon fiber coating method according to the present invention is characterized in that a coating is formed on the carbon fibers while rotating the holder that holds the carbon fiber sheet.

Furthermore, the carbon fiber coating formation device of the present invention is a carbon fiber coating formation device that forms a coating by adhering positively ionized coating material to the surface of carbon fibers to which a negative voltage has been applied within a vacuum container, and is characterized in that it includes a holder that holds both ends of a carbon fiber sheet in which a large number of carbon fibers are aligned into a sheet shape, a vibrator that micro-vibrates the carbon fiber sheet via the holder, and tensioning means that imparts a predetermined tension to the carbon fiber sheet held by the holder , and forms a coating on each of the carbon fibers while micro-vibrating each of the carbon fibers with the vibrator.

The carbon fiber coating forming device according to the present invention is also characterized by having a rotation drive means for rotating the holder that holds the carbon fiber sheet.

The carbon fiber coating forming device according to the present invention is also characterized in that the holders are provided in multiple numbers radially around the axis of rotation of the rotary drive means.

According to the carbon fiber coating forming method and device of the present invention, both ends of a carbon fiber sheet in which many carbon fibers are aligned in a sheet shape are held by holders, and a coating is formed on each carbon fiber while each carbon fiber is slightly vibrated by a vibrator through the holder. This improves the adhesion of the coating material and allows the coating to be formed evenly on the surface of each carbon fiber, making it possible to mass-produce carbon fiber sheets in which a coating is formed evenly on the surface of each carbon fiber.

1 is a schematic vertical cross-sectional view of a carbon fiber coating forming apparatus according to an embodiment of the present invention. FIG. FIG. 2 is a schematic cross-sectional view of the carbon fiber coating forming apparatus of the present embodiment.

The carbon fiber coating method and device of this embodiment is a method of forming a coating by attaching a positively ionized coating material to the surface of carbon fibers to which a negative voltage has been applied in a vacuum vessel to form a coating. As shown in FIG. 1, the carbon fiber coating device 10 of this embodiment is mainly composed of a vacuum vessel 1, a plurality of coating material supply sources 2, 2... provided on the peripheral wall of the vacuum vessel 1 to supply the coating material, a pair of upper and lower holders 3, 3 attached to the center of the vacuum vessel 1 to hold both ends of a carbon fiber sheet S formed by aligning a large number of carbon fibers into a sheet shape, an exhaust pipe 4 for evacuating the inside of the vacuum vessel 1, and an introduction pipe 5 for introducing an inert gas such as argon into the vacuum vessel 1.

The coating material supply source 2 in this embodiment is equipped with an unbalanced magnetron, and the coating material set in this coating material supply source 2 is evaporated by arc discharge, and the evaporated coating material is positively ionized. On the other hand, a negative bias voltage is applied to the carbon fiber sheet S through the holder 3 by an external power source (not shown). This causes the positively ionized coating material to collide with the surface of each carbon fiber in the carbon fiber sheet S, and the coating material is attached to the surface of each carbon fiber to form a coating.

The carbon fiber coating forming device 10 of this embodiment forms a coating by an ion plating method using arc discharge, but may also form a coating by, for example, an ion plating method using glow discharge or a sputtering method. In addition, to evaporate the coating material, a heating evaporation source such as a resistance heating method, an electron beam heating method, a high-frequency induction heating method, or a laser heating method may be used, and in order to generate plasma that positively ions the coating material, a direct current discharge method, a microwave discharge method, a bias probe discharge method, or the like may be used.

The carbon fiber sheet S can be a spread sheet obtained by passing an air flow through a carbon fiber bundle in which a large number of carbon fibers have been aligned in advance and spreading it into a sheet. This spread sheet can be obtained by a known fiber spreading device (Patent Publication No. 3907660). This fiber spreading device provides multiple support members at the ventilation opening of a wind tunnel tube that guides the air flow, and while the carbon fiber bundle traveling through the ventilation opening is supported by these multiple support members, an air flow is passed from a direction perpendicular to the traveling direction of the carbon fiber bundle to spread the carbon fiber bundle. With this fiber spreading device, the carbon fiber bundle can be spread in stages at small intervals while maintaining a constant posture with the multiple support members, and a spread sheet in which the spacing between each carbon fiber is approximately uniform can be obtained.

Coating materials include metals that do not react with carbon to form carbides, such as Ru, Rh, Pd, Os, Ir, and Pt, as well as other metals such as Al, Zn, Ti, and Ni. In addition, a coating made of a compound of each metal and a reactive gas such as nitrogen or oxygen may be formed on the surface of the carbon fiber, or multiple layers of coatings may be formed on the surface of the carbon fiber.

As shown in Figures 1 and 2, a cage-shaped frame 31 is provided inside the vacuum vessel 1 of this embodiment so as to be rotatable by an external rotary drive means 6. An upper support rod 32 is provided on the top of this frame 31 via a vibrator 7, and a lower support rod 33 is provided on the bottom of the frame 31 in parallel with the upper support rod 32.

Each pair of upper and lower holders 3 is made of gripping members that hold the front and back sides of the carbon fiber sheet S, and is detachably attached to the upper support rod 32 and the lower support rod 33, respectively. That is, the upper holder 3 is provided with a hook 34 that is hooked onto the upper support rod 32, while the lower holder 3 is provided with a detachable coil spring as tensioning means 8 that is hooked onto the lower support rod 33. In this way, the carbon fiber sheet S is set in the vacuum vessel 1 by the pair of upper and lower holders 3, 3 with a predetermined tension applied by the tensioning means 8.

In this embodiment, a total of eight upper support rods 32 and eight lower support rods 33 are provided radially from the rotation axis A of the frame 31 driven by the rotation drive means 6, and a total of eight carbon fiber sheets S can be set simultaneously in the vacuum vessel 1 using the eight pairs of upper and lower holders 3.

When forming a coating on a carbon fiber sheet S using the carbon fiber coating forming device 10 of this embodiment, first, an inert gas such as argon is introduced into the vacuum vessel 1, and a predetermined degree of vacuum is maintained inside the vacuum vessel 1. Then, the rotary drive means 6 is operated to continuously rotate the carbon fiber sheet S around the central axis A via the holder 3, and the vibrator 7 is operated to micro-vibrate the carbon fiber sheet S via the holder 3. Then, in this state, the coating material supply source 2 is operated to attach the coating material positively ionized by arc discharge to the carbon fiber sheet S to which a negative voltage is applied, forming a coating on the surface of each carbon fiber.

In this way, according to the carbon fiber coating method and coating forming device 10 of this embodiment, both ends of the carbon fiber sheet S, which is made by arranging a large number of carbon fibers into a sheet shape, are held by the holder 3, and each carbon fiber is slightly vibrated by the vibrator 7 through this holder 3 while ion plating is performed to form a coating on each carbon fiber. This makes it easier for the positively ionized coating material to reach the back side of each carbon fiber (the side opposite the nearest coating material supply source 2), further improving the adhesion of the coating material and allowing a more even coating to be formed on the surface of each carbon fiber.

In addition, according to the carbon fiber coating method and coating forming device 10 of this embodiment, a coating can be formed evenly on the surface of each carbon fiber when a large number of carbon fibers are aligned in a sheet shape, making it possible to mass-produce carbon fiber sheets in which a coating is formed evenly on the surface of each carbon fiber.

In addition, in this embodiment, the carbon fiber sheet S is a spread sheet in which a carbon fiber bundle in which a large number of carbon fibers have been aligned in advance is spread by air flow. This ensures uniform gaps between the carbon fibers of the carbon fiber sheet S, and reduces contact between the carbon fibers during micro-vibration. This also allows a more uniform coating to be formed on the surface of each carbon fiber.

In addition, in this embodiment, a predetermined tension is applied to the carbon fiber sheet S by the tension applying means 8, so that the carbon fiber sheet S can be held more stably while each carbon fiber is subjected to micro-vibration, which also allows a more uniform coating to be formed on the surface of each carbon fiber.

In addition, this embodiment is equipped with a rotary drive means 6 that rotates the holder 3 that holds the carbon fiber sheet S, and multiple holders 3 are provided radially around the rotation axis A, so that multiple carbon fiber sheets S can be coated simultaneously, allowing for mass production of carbon fiber sheets S with an even coating formed on the surface of each carbon fiber.

Although the carbon fiber coating method and coating device of this embodiment have been described above, the present invention can be implemented in other embodiments. The present invention can be implemented in various forms with improvements, modifications, and variations based on the knowledge of those skilled in the art, without departing from the spirit of the invention. In addition, the present invention may be implemented in a form in which any of the invention-specific matters are replaced with other technology within the scope of the same action or effect, and an invention-specific matter that is integrally configured may be composed of multiple members, or an invention-specific matter that is composed of multiple members may be implemented in a form in which it is integrally configured.

The carbon fiber coating method and device according to the present invention allows for the mass production of carbon fiber sheets with an even coating formed on the surface of each carbon fiber, making them suitable for use in the manufacture of metal composite materials reinforced with carbon fiber. In addition, carbon fiber sheets with catalytic metal coatings such as Pt formed on the surface of each carbon fiber can be used, for example, as a cheaper component material for the electrode catalyst layer of a fuel cell.

Reference Signs List 10 Carbon fiber coating forming apparatus 1 Vacuum vessel 2 Coating material supply source 3 Holder 4 Exhaust pipe 5 Inlet pipe 6 Rotation drive means 7 Vibrator 8 Tension applying means A Rotation axis S Carbon fiber sheet

Claims (5)

A method for forming a coating on carbon fibers, comprising the steps of: depositing a positively ionized coating material on a surface of carbon fibers to which a negative voltage is applied in a vacuum chamber to form a coating, the method comprising the steps of:
a carbon fiber sheet in which a large number of carbon fibers are aligned in a sheet shape is held at both ends by a holder, and a coating is formed on each of the carbon fibers while micro-vibrating each of the carbon fibers by a vibrator through the holder ;
The method for forming a coating on carbon fibers is characterized in that the carbon fiber sheet used is a spread fiber sheet prepared by passing an air flow through a carbon fiber bundle in which a large number of carbon fibers have been aligned in advance and spreading the fibers into a sheet shape . 2. The method for forming a coating on carbon fibers according to claim 1 , wherein the coating is formed on the carbon fibers while rotating the holder that holds the carbon fiber sheet. A carbon fiber coating forming apparatus for forming a coating by attaching a positively ionized coating material to a surface of a carbon fiber to which a negative voltage is applied in a vacuum chamber, comprising:
A holder for holding both ends of a carbon fiber sheet in which a large number of carbon fibers are aligned in a sheet shape;
a vibrator that vibrates the carbon fiber sheet slightly through the holder;
and a tension applying means for applying a predetermined tension to the carbon fiber sheet held by the holder,
A carbon fiber coating forming apparatus, characterized in that a coating is formed on each of the carbon fibers while micro-vibrating each of the carbon fibers with the vibrator. 4. The carbon fiber coating forming apparatus according to claim 3, further comprising a rotation drive means for rotating said holder which holds said carbon fiber sheet. 5. The carbon fiber coating forming apparatus according to claim 4 , wherein a plurality of said holders are provided radially around a rotation axis of said rotation drive means.

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