JP2783807B2 - Carbon fiber reinforced carbon composite material and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a carbon fiber-reinforced carbon composite material reinforced with carbon fibers using carbon as a matrix, and a method for producing the same.

[Prior Art] A carbon fiber reinforced carbon composite material is called a C / C composite, and is used as a heat-resistant material in the space and aircraft fields. U.S. Patent No. 3 discloses a method for producing this C / C composite.
Nos. 734797 and 4201611, British Patent No. 1360887, JP-A-49-62768 and 54-101985, and JP-B-62-250
There is one described in No. 94. In one example,
Preform body of nonwoven fabric or woven fabric, impregnated with thermosetting resin or pitch such as phenol, furan and epoxy,
Alternatively, a prepreg body is prepared by coating. Next, the prepreg bodies are laminated to form a multilayer body, integrated by press molding or the like, and then fired to carbonize and graphitize the matrix resin. In addition, if necessary, this impregnation and firing are repeated to increase the density. In another example, a carbon fiber reinforced carbon composite material is produced by layering a nonwoven fabric, performing needle punching on the nonwoven fabric, producing a preform, then impregnating the resin, firing and carbonizing.

[Problems to be Solved by the Invention] However, the C / C composite manufactured in this manner is composed of a nonwoven fabric or a woven fabric which is a raw material, and a single fiber of 1,000 to 4,000 fine strands. There is a problem that impregnation or coating with a thermosetting resin or the like does not penetrate into the interior of the tow-shaped fiber alone because it is in a so-called tow (long fiber, filament) shape. For this reason, after carbonization and firing, cracks are generated at the interface with the matrix fiber, and layer-like peeling and cracking are likely to occur.

In addition, there is a problem that local imbalance in strength occurs, and when this C / C composite is used, delamination and deformation occur in layers.

In order to solve these problems, a C / C composite formed and fired using a prepreg obtained by kneading short fibers with a matrix material such as a thermosetting resin has been developed. However, the short fiber reinforced carbon material has a small absolute area and a poor impact resistance because the area occupied by the fibers is small and the spacing between the fibers is large. Furthermore, this short fiber reinforcing material has the disadvantage that the strength in the direction along the surface is lower than the strength in the direction perpendicular to the surface.

The present invention has been made in view of such problems, and has improved strength in the direction along the surface of the laminated nonwoven fabric, and has a carbon fiber reinforced carbon composite material that satisfies the requirements of increasing the size and complicating the shape. It is an object of the present invention to provide a manufacturing method thereof.

[Means for Solving the Problems] A carbon fiber reinforced carbon composite material according to the present invention has a three-dimensional structure in which nonwoven fabrics are laminated, wherein the nonwoven fabric includes a reinforcing material made of carbon fibers and a space portion of the reinforcing material. A carbonaceous matrix material contained therein, and a powdery, whisker-like or short-fibrous filler made of a material selected from carbon, metal, and ceramics dispersed in the carbonaceous matrix material; The filler and the filler are arranged in the thickness direction at the lamination interface of the nonwoven fabric.

The method for producing a carbon fiber reinforced carbon composite material according to the present invention comprises, in a base liquid composed of a synthetic resin liquid, graphite powder, carbon black powder, short carbon fiber, short graphite fiber, synthetic resin powder, pitch powder, mesophase pitch powder, One or two selected from coke powder, ceramic powder, metal powder, metal short fiber, Si ₃ N ₄ whisker, SiC whisker and ceramic short fiber
A mixture liquid containing at least one type of filler is coated on the surface of a nonwoven fabric made of carbon fiber or a mixture of carbon fibers and organic fibers, and then, after laminating the nonwoven fabric, needle punching is performed a plurality of times with a plurality of needles. Thus, a prepreg body having a three-dimensional structure is obtained.

[Action] In the present invention, the needle is inserted (punched) in a state where the mixed solution applied on the nonwoven fabric containing the carbon fiber (non-woven half mat raw cotton) is sandwiched between the nonwoven fabrics. If the liquid is in the form of a paste, this paste layer can penetrate in the thickness direction of the nonwoven fabric. Thereby, the filler applied and supported on the warp can be distributed at a sufficient density in the thickness direction,
A filler can be present vertically inside the nonwoven fabric. And since carbon fibers and fillers are arranged in the thickness direction at the lamination interface of the nonwoven fabric, the strength against delamination is extremely high. By controlling the number of punches (arrangement density of the needles) or the distribution of the needles in the needle punching, the strength and performance of a carbon fiber reinforced composite material having a large or complicated shape can be made uniform.

[Examples] In order to achieve the above-mentioned object of the present invention, the present inventors initially laminated a nonwoven fabric in a layered form, made a hole in a direction perpendicular to the layer surface by so-called needle punching, and also made a fiber in the thickness direction. Has been developed. And
The nonwoven fabric was impregnated with a mixed solution containing a filler (carbon powder, Si ₂ N ₄ , SiC whisker, etc.), and the impregnation and firing were repeated.

In order to add a powdery filler to the interior of the C / C composite, we attempted to impregnate the filler from the outside with a liquid suspension, but due to the filter effect of the non-woven fabric, the filler only adhered to the surface and went into the interior. It could not be impregnated.

In particular, in the case of a nonwoven fabric having a high carbon fiber content, the weight per unit area is limited due to the problem of resistance to needle punching, and it is difficult to obtain a high-density product. For this reason, the deformation at the time of impregnation and sintering is large, and a product having a predetermined size cannot be obtained.

Then, the present inventors first performed so-called needle punching after coating the surface of the nonwoven fabric with the mixed solution containing the filler. As a result, the filler was pushed into the inside of the nonwoven fabric and distributed at a sufficient density in the thickness direction. The present invention has been made based on such findings.

Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a schematic view showing the method of the embodiment. The nonwoven fabric 1 is made of carbon fiber or a mixture of carbon fiber and organic fiber. After coating the surface of the nonwoven fabric 1 with the mixed solution 2, a plurality of sheets (four sheets in the illustrated example) are laminated.

The mixed liquid 2 uses a synthetic resin liquid as a base liquid, and a filler is added to the base liquid. As the filler, powdery, whisker-like or short-fiber carbon, metal, ceramics, synthetic resin, or a mixture thereof, which can serve as a reinforcing material for the carbonaceous matrix, is used. Specifically, for example, graphite powder, carbon black powder, short carbon fiber, phenol resin powder, epoxy resin powder, pitch powder, mesophase pitch powder, coke powder, stainless steel, nickel, steel,
Metal powder such as aluminum, brass or cast iron or metal short fiber, Si ₃ N ₄ whisker, SiC whisker, ceramic short fiber and the like. One or more of these fillers are added to the base liquid.

The nonwoven fabric 1 preferably has a basis weight of 5 g / m ² or more. If the basis weight is less than 5 g / m ^2, it is difficult to form a non-woven fabric and it is difficult to apply.

The mixed liquid 2 is in the form of a paste or liquid, and preferably has a weight ratio to the nonwoven fabric 1 of 0.5 to 300 times. When the weight ratio is less than 0.5, the effect of adding the filler is insufficient. On the other hand, if the weight ratio exceeds 300 times, the original performance of the nonwoven fabric cannot be exhibited.

The plurality of needles 4 are implanted on the flat support 3. As shown in FIG. 2, the needle 4 has a needle-shaped blade 5 and an herb 6 projecting laterally from the blade 5.
And The needles 4 are preferably implanted at an arrangement density of 5 needles / cm ² or more. Needle 4 arrangement density is 5
If the number is less than this / cm ² , the fiber extending in the thickness direction slips due to the rigidity of the carbon fiber, and it is difficult to distribute the filler at a sufficient density in the thickness direction.

The needle 4 is connected to the nonwoven fabric 1 as shown by an arrow 7.
The needle 4 group is inserted (punched) many times into the laminated nonwoven fabric 1 by reciprocating vertically to the surface of the nonwoven fabric. The mixture 2 is coated on the surface of the nonwoven fabric 1, and the mixture 2 is interposed between the nonwoven fabrics 1. For this reason, when the punching of the needle 4 into the nonwoven fabric 1 is repeated, the carbon fibers are drawn by the needles 4 and arranged in a direction perpendicular to the plane of the nonwoven fabric, and the mixed liquid between the surface of the nonwoven fabric 1 and the interlayer. 2 are pushed into the nonwoven fabric 1. The filler is present in each nonwoven fabric 1 so as to extend in the thickness direction, and between the layers, as schematically shown in FIG. 1, extends over both upper and lower layers perpendicular to the layer interface. Exists.

Most preferably, the needle is inserted perpendicular to the surface of the nonwoven. However, the effects of the present invention can be sufficiently obtained if the inclination angle of the needle is within a cone angle inclined at an angle of 45 ° with respect to a direction perpendicular to the surface of the nonwoven fabric. If the angle of inclination of the needle exceeds 45 °, the inserted needle easily slides along the surface of the nonwoven fabric, and it is difficult to obtain the effect of needle punching.

Next, if necessary, a plurality of (for example, four) other nonwoven fabrics 1 are laminated on the nonwoven fabric 1 after the needle punching, and the punching with the needles 4 is performed again, and the carbon fiber and the filler are reduced in the thickness of the nonwoven fabric 1. Distribute in the direction. In this way, by repeating the lamination of the nonwoven fabric 1 to which the mixed solution is applied and the needle punching, a so-called three-dimensional structure prepreg body in which a predetermined number of the nonwoven fabrics 1 are integrally laminated is obtained.

Thereafter, the prepreg body is isotropically pressed at a pressure of, for example, 500 kgf / cm ² or more to increase the density. The pressure in this isotropic pressing step is preferably 500 kgf / cm ² or more. If the pressure is less than 500 kgf / cm ² , the filler may not be sufficiently uniform, and the performance may be deteriorated.

Next, after drying the prepreg body, for example, 150 ℃
And heat to cure. Thereafter, the prepreg body is charged into a carbonization firing furnace, and heated to, for example, 1000 ° C. to perform a carbonization firing treatment.

The matrix material of the carbon fiber reinforced carbon composite material manufactured in this way is mainly composed of the carbon material obtained by carbonizing and firing the synthetic resin contained in the base liquid. If a thermosetting resin such as phenol, furan and epoxy is used as the synthetic resin, carbonized and baked to be a glassy carbon, and the base liquid contains graphite which is soft carbon or pitch and / or coke which becomes baked to become soft carbon. If so, these become so-called soft carbon, and as a result, a matrix material composed of a composite carbon of glassy carbon and soft carbon can be formed.

Next, test results of actually producing a C / C composite by the method of the present invention will be described.

Example 1 A tow-like carbon fiber having a tensile strength of 300 kg / mm ² class and a polyester fiber were passed through a carding machine at a weight ratio of 80:20 to prepare a nonwoven fabric. This non-woven fabric is cut into a predetermined shape to reduce the width.
A nonwoven fabric having a length of 100 mm and a length of 200 mm was obtained. Next, the nonwoven fabric was arranged on a table, and pastes (No. 1 to No. 3) having the compounding ratios shown in Table 1 below were applied.

Then, the nonwoven fabric was laminated while applying the paste, and needle punching was performed so as to be 10 pieces / cm ² each time the lamination was performed. The nonwoven fabric was laminated in 20 layers. 15 prepregs
After heating to 0 ° C for 40 minutes for curing, 100
The mixture was heated at 0 ° C. for 5 hours and fired to obtain a C / C composite having a specific gravity of 1.5 g / cm ² and a porosity of 10%. The basis weight of the nonwoven fabric was 200 g / m ² .

The physical properties of the obtained C / C composite are shown in Table 2 below.

As is clear from Table 1, when any paste of the mixed liquid of the present invention is applied, the paste has a high density, a high bending strength and a high compressive strength, and an extremely high compressive strength in the direction along the lamination interface. high. Furthermore, the results of the brake test by the method of SAE J661 showed that the mixed liquid had better sliding properties than the mixed liquid in the table, and the mixed liquid had better sliding properties than the mixed liquid. This C / C composite did not exhibit any of delamination, blistering and cracking.

Example 2 A nonwoven fabric was prepared by blending carbon fibers and polyvinyl chloride organic fibers at a weight ratio of 90:10. Example 1
Is the same as The application of the mixed solution (the mixed solution of Example 1) and the punching of this nonwoven fabric at a punching number of 10 pieces / cm ² were repeated to laminate 20 nonwoven fabrics. The curing conditions and the carbonization and firing conditions are the same as in Example 1. The physical properties of the C / C composite obtained in this way are shown in the following
It is shown in the table.

Similarly, in this example, a C / C composite having a very high peel strength and a high density and a high strength was obtained.
No delamination, swelling or cracking occurred.

Example 3 A nonwoven fabric (size: 100 mm x 100 mm, weight: 100 g) in which carbon fibers and polyvinyl chloride organic fibers are 90:10 is divided into 20 pieces, and 100 g of phenol resin powder and 100 g of furfuryl alcohol are added.
In this solution, 50 g of graphite powder, CF mill 1
0 g was mixed. This paste is interposed between the laminated nonwoven fabrics, and needle punching is performed 5 times / cm ² or more in units of several sheets, and after all the sheets are finished, the paste is applied to the upper and lower ends to finish. This sample is subjected to a cold isostatic pressing (CIP) treatment at 2000 kgf / cm ² and then dried at a low temperature of 100 ° C. or less for 3 days. After drying, press molding at a 180 ° C. and 50 kgf / cm ² conditions, up to 500 ° C. 10 ° C. / hour or less, 30 ° C. up to 1000 ° C. or higher
Firing was performed in a non-oxidizing atmosphere at a heating rate of / h to obtain a C / C composite. Similarly, the composition of the paste was changed as shown in Table 4 to obtain the results shown in Table 5.

Comparative Example Twenty layers of the same nonwoven fabric as in Example 2 were laminated, and were subjected to a curing treatment and a carbonizing and firing treatment under the same conditions as in Example 2 without punching.

As a result, the physical properties of the obtained C / C composite are as shown in Table 6 below, and all the properties are lower than those of Examples 1 and 2.

In addition, when the mixture was applied, peeling and cracking occurred during use, and when the mixture was applied,
Peeling and cracking occurred during the manufacturing process.

[Effects of the Invention] According to the present invention, a powdery, fibrous or whisker-like filler can be added to the inside and between layers of a nonwoven fabric in the thickness direction, so that carbon having a remarkably high strength in the direction along the surface is provided. Fiber reinforced carbon composites can be manufactured.
In addition, in terms of sliding characteristics, the performance can be improved by the addition amount of these powders and fillers. Furthermore, since the present invention integrates each nonwoven fabric by inserting a plurality of needles into the nonwoven fabric, reinforcing fibers,
The uniformity with the matrix material is good, and a composite material or a large structure having a complicated shape can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a method of an embodiment of the present invention, and FIG. 2 is a schematic diagram illustrating a structure of a needle. 1; non-woven fabric, 2; mixture, 4; needle, 5; blade, 6; herb

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-209883 (JP, A) JP-A-60-16805 (JP, A) JP-A-62-171908 (JP, A) JP-A 63-209 99940 (JP, A) JP-A-62-230670 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 35/83

Claims (10)

(57) [Claims] 1. A three-dimensional structure in which a nonwoven fabric is laminated, wherein the nonwoven fabric includes a reinforcing material made of carbon fiber, a carbonaceous matrix material existing in a space of the reinforcing material, and a carbonaceous matrix material. Dispersed, carbon, powder having a material selected from metal and ceramics, having a whisker-like or short fiber-like filler, the carbon fiber and the filler in the thickness direction at the lamination interface of the non-woven fabric A carbon fiber reinforced carbon composite material which is arranged. 2. The carbon fiber reinforced carbon composite material according to claim 1, wherein said carbonaceous matrix material is composed of glassy carbon and soft carbon. 3. The filler according to claim 1, wherein the filler is graphite powder, carbon black powder, short carbon fiber, short graphite fiber, coke powder, metal powder,
The carbon fiber reinforced carbon composite material according to claim 1, wherein the carbon fiber reinforced carbon composite material is composed of one or more materials selected from short metal fibers, ceramic powder, ceramic whiskers, and short ceramic fibers. 4. A base liquid comprising a synthetic resin liquid, graphite powder,
Carbon black powder, carbon short fiber, graphite short fiber, synthetic resin powder, pitch powder, mesophase pitch powder, coke powder,
A mixture of one or more fillers selected from ceramic powder, metal powder, metal short fiber, Si ₃ Ni ₄ whisker, SiC whisker and ceramic short fiber is added to carbon fiber or carbon fiber and organic fiber. Coating or spraying the surface of a non-woven fabric made of a mixed weave, and then laminating the non-woven fabric, followed by needle punching with a plurality of needles a plurality of times to obtain a prepreg body, Manufacturing method of carbon composite material. 5. The carbon fiber reinforced carbon composite material according to claim 4, wherein the prepreg body is carbonized and fired by at least one of pressure, drying, heat curing, polymerization, carbonization and infusibilization. Manufacturing method. 6. The needle punching density is 5 needles / cm ^2.
The method for producing a carbon fiber reinforced carbon composite material according to claim 4, wherein: 7. A non-woven fabric having a basis weight of 5 g / m ² or more,
The method according to claim 4, wherein the mixture is a paste or a liquid, and has a weight ratio of 0.5 to 300 times the nonwoven fabric. 8. The carbon fiber reinforced carbon according to claim 4, wherein the pressing step isotropically presses the plurality of laminated prepreg bodies at a pressure of 500 kgf / cm ² or more. Manufacturing method of composite material. 9. The method for producing a carbon fiber reinforced carbon composite material according to claim 4, wherein after firing, glassy carbon exists around the carbon fiber, and the remaining area is occupied by soft carbon. . 10. The method for producing a carbon fiber reinforced carbon composite material according to claim 4, wherein the amount of the carbon fibers is 1 to 99 times the amount of the organic fibers.