JPS5944381B2 - Manufacturing method of carbon fiber reinforced metal composite material prepreg - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a prepreg for use in producing a carbon fiber reinforced metal composite material (hereinafter abbreviated as CFRM) using carbon fiber as a reinforcing material.

Conventionally, composite materials using carbon fiber as a reinforcing material and metal have a lightweight structure that combines the high elasticity, high strength, and lightness of carbon fiber with the formability, heat resistance, electrical conductivity, and thermal conductivity of metal. Although it is seen as a promising material, it has been difficult to uniformly and firmly bond and mold the metal as the base material and the carbon fiber as the reinforcing material at the manufacturing stage of the composite material.

The reason for this is that it is difficult to uniformly mix the molten metal base material and carbon fiber, and when carbon fiber and base metal are laminated and heated and pressed to make a composite material, the carbon fiber and metal The problems include that the bond strength is weak and peeling between layers tends to occur, and that the strength of the composite material decreases when the metal reacts with the carbon fibers and tends to form carbide.

As a result of research on these issues, the present inventors found that a prepreg with specific properties has excellent handling properties, and that CF RM manufactured using this prepreg has good performance due to uniform mixing of fibers and metals and strong bonding. We have discovered that such a prepreg can be obtained by subjecting a thin sheet consisting of a monofilament layer of carbon fibers to ion blasting or vacuum deposition.

The present invention provides a prepreg that is easy to handle and allows production of high-performance CFRM.

That is, in the present invention, carbon fibers are made into a thin sheet with an average of 10 layers or less, with each single fiber being one layer, and this is subjected to ion blasting or vacuum deposition to form a base metal layer around each single fiber. At the same time, a carbon fiber-reinforced metal having moderate flexibility and shapeability is obtained by partially point bonding the single fibers to each other using a base metal to obtain a thin sheet-like product having moderate flexibility and shapeability. This is a method for manufacturing prepreg for manufacturing composite materials.

This type of carbon fiber-metal prepreg allows the carbon fibers to be uniformly arranged in the CF RM, and the fibers are thin and the single fibers are point-bonded to each other with metal in the form of a sheet, which provides appropriate flexibility. It has excellent handling properties.

In addition, by manufacturing this using an ion blasting method or a vacuum evaporation method, it is possible to prevent the base metal from being included in an excessive volume ratio in this prepreg and CFRM, and to make the bond between the carbon fiber and the metal tighter. It can be done.

In the present invention, carbon fibers refer to so-called carbon fibers and graphite fibers in the commonly used sense, and it does not matter whether they are long fibers or short fibers.

The type of base metal formed around carbon fibers is A.
12MgtZntTi, Ni, Cu and other vaporizable metals and alloys.

These base metals directly or indirectly cover carbon fibers,
It is made of multilayered fiber material.

The multilayer structure fiber material is a fiber having a core layer of carbon fiber, a base metal layer as the outermost layer, and a third layer interposed in the middle as necessary.

When the base metal is used at its coating formation stage, at the CFRM manufacturing stage, or at the CFRM usage stage,
metals that can react with or dissolve carbon fibers that are essentially carbon, i.e. AA;
In the case of Ti, Ni, etc., a barrier layer is interposed between the carbon fiber and the base metal layer in order to prevent these.

This barrier is a layer of Ti, Si, or their carbides or nitrides, and even in the case of metals that do not easily react with carbon fibers, such as Mg, Zn, Cu, etc.
It can be used to improve its wettability.

Of course, you can use Ti even if you sacrifice some strength.

If it is desired to avoid contamination with impurities such as Si, it is possible to create a CF RM without intervening the barrier layer.

Usually the barrier is very thin, a few tenths of a micrometer or less, which is sufficient.

If the barrier layer becomes unnecessarily thick, the volume ratio of the barrier layer becomes high, which deteriorates the performance of the CFRM.

The aggregate of fibrous materials may be a unidirectionally aligned sheet of fibrous materials, a random web, a nonwoven fabric, or the like.

The fiber material is in the form of a thin sheet, with an average of 1 layer of single fibers.
It is necessary that the number of layers is 0 or less, preferably 3 to 5 layers.

During ion blasting or vacuum deposition, the base metal layer uniformly covers the carbon fibers, and at the same time, the base metal adheres the fibers at the contact points where the single fibers partially touch each other, resulting in moderate flexibility and regular shape. CFRM with gender
It becomes prepreg.

Carbon fiber volume content in prepreg is 5-70%
It is preferably 20 to 60%.

This is because the reinforcing effect is weak when the volume content of carbon fiber is low.
This is because molding becomes difficult if the sparrow is too large.

To obtain CFRM using this CFRM prepreg, the required number of prepregs are laminated in any direction, heated under pressure so that each metal fuses with each other and becomes integrated, and the carbon fiber volume content is adjusted according to the application. CFRM.

This prepreg is manufactured by an ion blasting method or a vacuum evaporation method.

Other methods for forming the base metal layer include infiltration, plasma spraying, and plating, but the first infiltration method has a narrow range of adjustment for the carbon fiber volume content of CFRM. Furthermore, when the prepreg is pulled up from the molten metal bath, the metal penetrates between the fibers, solidifies, and becomes integrated into a rod-like shape.
This makes workability worse when creating M.

In the second plasma spray method, it is difficult to obtain a CFRM in which carbon fibers are uniformly dispersed because the carbon fibers are not uniformly coated with metal.

The third plating method makes it difficult for the fibers to clump together, resulting in C
In addition to the difficulty in working with FRM, it is extremely difficult to coat AA and the like.

The prepreg obtained by the ion blating method of the present invention by the vacuum evaporation method has carbon fibers coated with a base metal for each single fiber, and has appropriate flexibility and shapeability, which is a disadvantage of the three methods described above. There is no.

Furthermore, there are advantages such as good bonding between carbon fiber and metal, and metal coating without oxidation.

Formation of metal layer by ion blating method is lXl0
In a vacuum of Torr or less, using carbon fiber or carbon fiber with a single barrier layer as a cathode, 10.5KV to 2. OKV
to be applied.

The inside of this system is set to an argon atmosphere of about 0.5 x 10 -2 to 5 x 1 O -2 Torr, and the base metal is heated and evaporated by resistance heating, electron beam irradiation heating, high frequency induction heating, etc.

This metal evaporation is activated (ionized) in the plasma region and condenses as a metal layer on the surface of the fibers arranged at the cathode.

The higher the carbon fiber temperature, the denser the metal layer is formed.
Al, Ti, Ni on the carbon fiber surface that does not have a single barrier layer
When forming a metal layer that causes reactions such as This is not desirable because it occurs.

Prior to forming the metal layer on the surface of the carbon fiber, it is preferable to etch the surface of the fiber.

Although known etching methods can be employed, plasma etching is particularly preferred, which is performed continuously as a step prior to ion blasting.

This method is carried out in an argon atmosphere of 0.5 x 10-2 to 5 x 1 O-2 Torr. This is a method in which etching is performed using plasma generated by a discharge caused by a discharge voltage applied to approximately OKV.

When etching is performed in this manner, deposits on the carbon fiber surface are removed and a metal layer is formed directly on the fiber surface.

The method of forming a barrier layer by ion blating differs depending on the type of barrier layer.

A single barrier layer of Si and Ti can be formed in the same manner as the formation of the metal layer described above, and when the temperature of the carbon fiber is raised, a single barrier layer of these carbides is formed.
When performed in a nitrogen atmosphere, a single nitride barrier layer is formed.

Preferred combinations of base metal and barrier layer are shown in the following table.

Formation of the metal layer by vacuum evaporation evaporates the metal in a vacuum of less than 1X10-'Torr without applying electric power to the fiber.

Vacuum deposition differs from ion brating,
Throwing P of metal atoms
Since there is no overflow, it is necessary to evaporate the metal from both sides of the sheet.

Also in this case, it is preferable to perform plasma etching as the first step because it cleans the surface of the carbon fiber.

When carbon fibers are arranged in a thin sheet with an average of 10 layers or less, preferably 3 to 5 layers or less, and ion blasting or vacuum deposition is performed, the fibers are bonded to each other at their contact points at the same time as the metal layer is formed. It adheres and becomes a prepreg with appropriate flexibility and shapeability.

In this case, if the sheet has more than 10 layers with one layer of single fibers, the carbon fibers inside will not be covered with the metal layer, which is not preferable.

In addition, if the metal layer is formed in a state where the carbon fibers do not have sufficient shape, it is possible to create a sheet with a higher degree of shape by crimping only the contact points of the fiber material with light pressure and temperature. It is possible to obtain.

To obtain a CF RM using this prepreg, a required number of prepreg sheets are laminated, and the metals are bonded by applying pressure and heating.

Also, if necessary, place metal foil between the prepreg sheets.
It is also possible to insert metal powder, and it is also possible to form this prepreg sheet into a so-called sandwich structure by sandwiching it between metal plates.

The molding conditions to obtain CFRM vary depending on the base metal, and the atmosphere may be air or inert gas, but it is usually done in a vacuum when the base material is a metal that does not react with carbon fibers, or when a single barrier layer is provided. is 10 to 100k within the range of the melting point temperature of the base metal or 100℃ lower than the melting point.
It is preferable to apply a pressure of g/ffl.

If there is no barrier layer and the base material is a metal that reacts or dissolves with carbon fibers, the temperature should be 100°C above the melting point of the base metal.
It is preferable to mold at 100 to 1000 kg/cril in a temperature range from low temperature to 1/2 of the melting point expressed in absolute temperature.

The prepreg obtained by the method of the present invention will be explained with reference to the drawings.

Carbon fiber, which is the basic fiber material constituting the prepreg of the present invention, has a cross section of a multilayer structure as shown in FIGS. However, in some cases, a barrier layer 4 is interposed in the intermediate layer.

The prepreg of the present invention is composed of a fiber aggregate of such single fibers, and is in the form of a thin sheet with an average of 10 layers or less with each single fiber as one layer. (applied by vacuum evaporation)
It is point-adhesive and has appropriate flexibility and shapeability.

The fiber aggregate may be unidirectionally aligned or randomly oriented.

In the case of a unidirectional arrangement, the prepreg of the present invention has an appearance as shown in FIG.
It is connected with.

The cross section of this point bonded portion is as shown in FIG.

When the fiber aggregate is randomly oriented, the prepreg of the present invention has an appearance as shown in FIG.
are partially bonded to each other by point bonding portions 2 by the base metal.

The prepreg of the present invention is a thin sheet-like material having an average of 10 layers or less, and the number of layers is determined based on the single fiber layer.

The unidirectional prepreg consisting of an average of three layers of single fibers is the fifth
This is conceptually shown in the figure.

As described above, when the prepreg sheet for producing carbon fiber reinforced composite materials obtained by the present invention is used, it is easy to handle and has high performance with any orientation and carbon fiber volume content.
, CCFRM can be created.

The present invention will be explained below with reference to Examples.

Example 1 Untwisted 6,000 filament in vacuum system, diameter 9.2
μm carbon fiber (strength 220kg 1m, elastic modulus 19.5
t on / ii) was spread to a width of 18 mm and an average of 3 layers, sheets arranged in a row and high-purity Kl were arranged, and after the system was evacuated to below lXl0'Torr, argon gas was introduced. While maintaining the argon pressure at 2 x 10" Torr, apply a voltage of -1, OKV to the carbon fiber.
Plasma etching was performed for minutes.

After etching, kl is evaporated by resistance heating,
An was deposited at 1.0μIV″rT1in and ion-bladed to obtain a carbon fiber-aluminum prepreg sheet having a 4μm A1 layer.

This sheet is moderately flexible and has a diameter of 10 mr.
It was possible to wrap the wire around the pipe in parallel and at right angles to the pipe.

The carbon fiber volume content of this prepreg was 30%.

20 sheets of this prepreg are stacked in one direction, and the vacuum level is 2X1.
A CF RM having a carbon fiber volume content of 31% was obtained by heating and pressurizing at 0-5 Torr, 560° C., and 9001 y/cflL.

This CFRM had a strength of 45 Y/- in the fiber axis direction and good electrical conductivity.

Example 2 A web of 5 random average monofilament layers made of carbon fibers with a diameter of 9.0 μm and T were prepared in a vacuum system according to the method of Example 1.
5X10-5T after evaporating Ti at a deposition rate of 0.5 μm/min and performing ion blating.
Cu was evaporated from both sides of the random web in a vacuum of 3.0 μm/min at a deposition rate of 3.0 μm/min.

The obtained prepreg is moderately flexible, and the thickness of the coated metal layer is 0.1 μm for Ti and 8.0 μm for Cu.
m, and the carbon fiber volume content was 13%.

Ten carbon fiber-copper prepreg sheets obtained in this manner were laminated, and the vacuum degree was 2×10 −4 Torr s.
1000℃, 50kg/Cr? A CF RM having a carbon fiber volume content of 15% was obtained by heating and pressing with L.

Example 3 According to the method of Example 1, a unidirectionally arranged sheet (diameter 7.0 μm, 6,000 filaments) spread to an average of 3 layers and a width of 14 mm and Ti were placed, and the system was heated to 1×10' To
After evacuation to below rr, introduce nitrogen gas and increase the nitrogen pressure to 2X.
-1, OKV to carbon fiber while maintaining at 10-2 Torr
Plasma etching was performed for 5 minutes by applying a voltage of .

After 5 minutes had passed, the carbon fibers were heated to 200°C using a tank heater.

On the other hand, Ti was evaporated by resistance heating to form a titanium nitride coating on the carbon fiber surface at a deposition rate of 0.5 μm/min.

The thickness of the coating was 0.2 μm. Then lXl0-
After evacuation to below Torr, introduce argon gas,
Deposition rate 1.0 μm/ml using the same method as Example 1
2.5 μm of Al was coated by ion-blating at n, and a prepreg sheet with a three-layer structure of carbon-nitrogen titanium-aluminum was obtained.

Fifty sheets of this prepreg sheet were laminated in one direction and heated and pressed at a vacuum degree of 5×10' Torr, 650° C., and 50 kg/d to obtain a C F RM having Al as the base material.

The carbon fiber volume content of this CFRM was 35%, and the strength in the fiber axis direction was 58 kg/xi.

Example 4 According to the method of Example 1, a unidirectionally oriented sheet (diameter 7 μm, 12,000 filaments) with an average of two layers and a width of about 45 mm was placed and Mg was placed, and the system was heated to lXl0'T.
After evacuation to a pressure below 100 psi, argon gas was introduced and plasma etching was performed for 5 minutes by applying a voltage of 0.5 KV to the carbon fibers while maintaining the argon pressure at 1X10'' Torr.

After that, the graphite crucible containing Mg was heated by high frequency induction.
A moderately flexible carbon fiber-Mg prepreg sheet coated with 2.0 μm of Mg was prepared by evaporating the Mg and performing ion blasting at a deposition rate of 0.1 μm/min.

80 of these sheets were stacked and heated at 450°C1C in a N2 air flow.
C heated and pressurized at 15oo/ffl, with Mg as the base material
I got FRM.

The carbon fiber volume content of this product was 40%, and the strength in the fiber axis direction was 76 kg/mm.

Example 5 According to the method of Example 1, carbon fibers with a diameter of 7 μm and 6,000 filaments were spread to have an average thickness of 3 layers and a width of 14 mm.
i was evaporated by electron beam irradiation, and ion blating was performed with argon molecules at -1.5 KV and 0.5 x 1 O-2 Torr at a deposition rate of 0.6 μm/min.

By this ion blasting, Ni was coated to a thickness of 2.5 μm to obtain a moderately flexible prepreg sheet having a carbon fiber-Ni structure.

A total of 60 pieces of this prepreg were placed in a mold alternately in the 0 degree direction at 600℃, 500 kg/c, 11 yen, and I x 10.
CF with Ni as the base material heated and pressurized under a vacuum of 1 Torr
Got RM.

The carbon fiber volume content of this CFRM is 35%, 0 degrees, 9
The strength in the 0 degree direction was 45 kg/m4.

Example 6 According to the method of Example 3, carbon fiber bundles with a diameter of 7 μm and 6000 filaments were spread to have an average of one layer and a width of 43 mm, and Si
After vacuum evacuation to below IXIC)' Torr, N2 gas was introduced and the N2 pressure was increased to 1 x 1 O-2 Torr.
Pyrazma etching is performed by applying a voltage of -2, OKV to the carbon fibers while maintaining the temperature.

After that, the graphite crucible containing Si was heated by high frequency induction.
The Si was evaporated and Si3N4 was coated with a thickness of 0.3 μm.

Then, after evacuation to lXl0' Torr again, argon gas was introduced, Ti was evaporated by resistance heating, and ion blasting was performed to a thickness of 2.0 μm at a deposition rate of 0.5 μm/min, and the carbon fiber - silicon nitride - A titanium three-layer prepreg sheet was obtained.

This product had appropriate flexibility and shapeability.

200 sheets of this prepreg sheet were laminated in one direction, 16
Hot pressed at 50℃, 501y/ffl, lXl0-5torr, carbon fiber volume content 40%, strength 65kg
/- CFRM was obtained.

[Brief explanation of the drawing]

Figures 1a and b are cross-sectional views of a carbon fiber single fiber having a base metal around it, Figure 2 is a cross-sectional view of a point bonded portion, and Figure 3 is a point bonded portion of the unidirectional prepreg of the present invention. Fig. 4 is an overview diagram showing point bonding parts of the randomly oriented prepreg of the present invention, Fig. 5 is a conceptual diagram of the prepreg of the present invention consisting of an average of three layers of single fibers, 1...Carbon fiber , 2... point adhesive part, 3
...Base metal layer, 4...Barrier layer,
5...Metal coated carbon fiber.

Claims (1)

[Claims] 1 Carbon fibers are formed into a thin sheet with an average of 10 layers or less, with each single fiber being one layer, and this is subjected to ion blasting or vacuum deposition to form a base metal layer around each single fiber, and at the same time, the single fiber is formed into a thin sheet. For manufacturing carbon fiber-reinforced metal composite materials having moderate flexibility and shapeability, characterized in that a thin sheet-like material having moderate flexibility and shapeability is obtained by partially point-bonding each other with base metals. Prepreg manufacturing method.