JPH0532457A - Carbon fiber-reinforced carbon composite material and its production - Google Patents

Abstract

PURPOSE:To obtain a carbon fiber-reinforced carbon composite material useful especially as a brake material because of high strength while keeping the frictional characteristics of conventional friction material and, furthermore, usable widely in the field of aerospace material and other general C/C composite use. CONSTITUTION:The objective carbon fiber-reinforced carbon composite material is produced by bonding carbonized glassy carbon fine particles having spherical or granular form and carbonaceous fiber resistant to graphitization with a carbonaceous matrix composed of a baked resin. It can be produced by forming an agglomerate of glassy carbon fine particles, a carbonizable resin and carbonaceous long fibers, compression-molding the prepreg, baking and carbonizing in a non-oxidizing atmosphere to obtain a composite material composed of 2-35wt.% of carbonized glassy carbon fine particles, 5-50wt.% of carbonaceous material originated from the resin and 40-85wt.% of the carbonaceous long fibers. Both of the reinforcing fiber and the matrix of the obtained carbon fiber-reinforced carbon composite material have glassy structure essentially resistant to graphitization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber reinforced carbon composite material for use in aerospace materials such as rocket nozzles and brake materials for aircraft, or as brake materials for automobiles such as high speed racing cars, and a method for producing the same.

[0002]

2. Description of the Related Art Carbon fiber reinforced carbon composite materials (hereinafter C / C
Since it is excellent in high temperature strength and lightweight, it is a so-called optical edge composite material used for brake materials of aircrafts and high-speed racing cars, rocket nozzles and the like. This C / C composite is manufactured as follows, for example. First, a carbonaceous long fiber or its woven fabric is impregnated with or coated with a thermosetting resin such as phenol, furan and epoxy resin or pitch to prepare a prepreg body. Next, this prepreg body is laminated to form a multilayer body. Alternatively, the carbonaceous short fibers and the thermosetting resin or pitch are dispersed in water, and then an aggregate is prepared by a papermaking method. After integrating these multilayer bodies or aggregates by press molding or the like, the matrix resin is carbonized and graphitized. The C / C composite produced by the molding method using such carbonaceous long fibers has a big problem that gas swelling due to generation of thermal decomposition gas of the resin in the carbonization process and delamination and cracking due to contraction of the resin are likely to occur. there were.

As a measure against this problem, a method using a filler of graphite powder has been proposed (Japanese Patent Laid-Open No. 57-2098).
83). However, although the method using the graphite powder filler is improved, degassing becomes insufficient when the temperature rising rate is increased or when a thick C / C composite having a plate thickness of 5 mm or more is produced. As a result, swelling occurred, and microscopic cracks were generated between the layers due to resin shrinkage, so that sufficient strength could not be obtained. Further, since the obtained product has a mixture of graphitized portion and glassy carbon portion in carbonaceous matter, for example, the friction characteristics are different from the conventional glassy carbon-based brake material, and it takes a long time to handle it. There was also.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems, and as a result, have completed the present invention, and the purpose thereof is high strength and graphitization. (EN) A carbon fiber reinforced carbon composite material having a small number of parts and a method for producing the same.

[0005]

The above-mentioned object is to provide a carbon fiber reinforced carbon in which a carbide of spherical or granular glassy carbon fine particles and a non-graphitizable carbonaceous fiber are fixed in a calcined resin carbonaceous matrix. Composite materials and

[0006] An aggregate composed of glassy carbon fine particles, a carbonizable resin and a carbonaceous long fiber is prepared, and then the aggregate is pressure-molded, followed by firing and carbonization in a non-oxidizing atmosphere to obtain glassy carbon fine particles. 2 to 35 wt% of carbide
Carbon fiber reinforced carbon composite material (hereinafter abbreviated as C / C composite), characterized in that carbonaceous matter derived from resin is 5 to 50 wt% and carbonaceous long fiber is 40 to 85 wt%
It is achieved by the manufacturing method of.

In the method for producing the C / C composite of the present invention, the glassy carbon fine particles and the carbonizable resin are first diluted in a solvent to form a resin varnish, which is impregnated into carbonaceous long fibers to obtain a prepreg. Next, this prepreg body is laminated to form a multilayer body. Alternatively, the carbonaceous short fibers, the glassy carbon fine particles and the carbonizable resin are uniformly dispersed in water, and then an aggregate is prepared by a papermaking method. The precursor or molded body is produced by curing the resin of these multilayer bodies or aggregates by press molding autoclave molding or the like. The precursor compact thus obtained is calcined by normal pressure sintering, pressure sintering or a combination of both to obtain a C / C composite. The compounding amount of the glassy carbon fine particles is 2 to 35 wt% of the carbide of the glassy carbon fine particles in the C / C composite obtained by firing and carbonization, preferably 4
It is preferable to adjust the content to be about 20 wt%. If the blending amount is less than 2 wt%, the gas out of the pyrolysis gas of the resin generated during firing and carbonization is poor, and the shrinkage of the resin greatly affects gas swelling, delamination, cracks and the like. On the other hand, if it exceeds 35 wt%, a C / C composite will be obtained in which the adhesive strength between fibers is extremely low. The amount of the carbonizable resin compounded is 5 to 50 wt%, preferably 10 to 40 wt% of carbonaceous material in the C / C composite after firing and carbonization.
To be prepared. When the compounding amount is less than 5 wt%,
The interfiber adhesion of the obtained C / C composite is significantly reduced. On the other hand, if the blending amount exceeds 50 wt%, a large amount of pyrolysis gas is generated during firing and carbonization, and the resin shrinkage greatly affects gas swelling and cracking.

Furthermore, the amount of carbonaceous fiber is 40 to 85 wt% in the C / C composite obtained after firing and carbonization.
%, Preferably 50-80 wt%. When the amount of carbonaceous long fibers is less than 40 wt%, the reinforcing effect of the fibers is insufficient and the strength of the C / C composite decreases. On the other hand, if it is more than 85 wt%, the inter-fiber adhesive strength will be significantly reduced.

Next, the starting material will be described. Glassy carbon fine particles are spherical or granular high-purity carbon,
For example, a carbonized spherical or granular resin that has been carbonized by heat treatment can be used. The glassy carbon fine particles have a particle size of 100 μm or less, and the finer the better. If it exceeds 100 μm, it is difficult to disperse it uniformly in the varnish, and the obtained C / C composite has poor denseness and low strength. Since spherical or granular glassy carbon is a sphere having a substantially perfect shape and a uniform particle size, it has an advantage that gas generated in the carbonization process smoothly escapes to the outside through the particles. Further, since it is spherical, it does not damage the fiber and does not reduce the strength of the fiber.

As the carbonizable resin, a phenol resin, a furan resin, an epoxy resin, an acrylic resin, a polyimide resin or the like can be used, and any resin having a high residual carbon rate of 40% or more can be sufficiently used in the present invention. You can Above all, a phenol resin is particularly preferable because the resin is easy to handle, the characteristics of the molded product are good, and the cost is low. In addition, since the amount of gas generated during firing is large for resins with a residual coal rate of less than 40%, C
The / C composite easily causes gas swelling and cracking.
As the fiber, a fiber having a non-graphitizable structure such as PAN-based or rayon-based fiber can be used, and if PAN-based fiber is used, the most excellent strength can be obtained. The reason why the non-graphitizable property is set is that it has essentially the same structure as the carbonizable resin and the glassy carbon fine particles to be the matrix, and all the structures are non-graphitizable. As the form of the reinforcing fiber, a roving in which long fiber filaments are bundled are aligned in one direction, and a roving woven fabric gives an excellent strength, but the form of short fiber dispersion strengthening is also effective. Act on.

The glass carbon fine particles, the carbonizable resin and the carbonaceous long fiber may be blended, for example, by mixing the glassy carbon fine particles and the carbonizable resin with an organic solvent having a low boiling point such as methyl ethyl ketone, methanol, acetone, or toluene. After dissolving in a mixed solvent and impregnating the reinforcing fiber, a method of removing the organic solvent by using an oven, a vacuum dryer or the like, or between the glassy carbon small spheres and the carbonizable resin on at least one side with the reinforcing fiber interposed therebetween. There is a method of stacking release paper coated with a mixture and heating and pressurizing it with a heating roll to disperse and impregnate the reinforcing fiber with the resin, but the surface of the reinforcing fiber is uniformly glassy carbon fine particles and carbonizable resin. Any method may be used as long as it can be uniformly impregnated and coated. When the carbonaceous fiber is short fiber, there is a method of blending it into short fiber paper, preform sheet, etc. in the same way as long fiber, but glassy carbon fine particles, carbonizable resin and carbonaceous short fiber are mixed. There is also a method of papermaking or a method of simply dispersing and mixing the mixture, and subjecting the aggregate to pressure molding for blending. The present invention is not particularly limited to the method of blending the glassy carbon fine particles, the carbonizable resin and the carbonaceous fiber.

The aggregate compounded in the proportion shown in the present invention is heated and molded by a known appropriate method such as press molding and autoclave molding to obtain a precursor molded product. A C / C composite is obtained by firing the precursor compact thus obtained by normal pressure firing, pressure firing or a combination of both.
If necessary, the impregnation and firing may be repeated, or the chemical vapor phase or vapor deposition may be used to improve the density and enhance the strength.

[0013]

INDUSTRIAL APPLICABILITY The carbon fiber-reinforced carbon composite material obtained by the method of the present invention has both a reinforcing fiber and a matrix, which essentially have a non-graphitizable glass-like structure. Conventionally, C / has a non-graphitizable structure as a brake material
The C composite is the mainstream, and the product of the present invention is particularly excellent as a brake material in that it has the same strength as conventional friction characteristics and high strength. However, it is not limited to this, but can be widely used for aerospace materials and other general C / C composite applications. Further, by mixing the glassy carbon fine particles, it is possible to improve the outgassing property of the pyrolysis gas and reduce the shrinkage ratio of the resin, so that a high-strength C / C composite without gas swelling and cracks can be obtained. Therefore, since the repetition of impregnation-firing for densification is significantly reduced or unnecessary, the cost reduction over the conventional method can be achieved. Furthermore, even when the temperature rising rate is increased or the thickness is increased, cracks and the like do not occur, and it is possible to improve productivity and improve quality.

[0014]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. The characteristics of the C / C composites obtained in the examples and comparative examples were measured and evaluated as follows. (1) Presence or absence of delamination, cracks, etc. Visual observation and observation with a microscope were carried out, and it was judged by the presence or absence of continuous delamination or cracks of several mm on the cross section. (2) Bending test A test according to JIS K7203 was performed. (3) Ratio of carbonaceous matter derived from resin in C / C composite Glass carbon fine particles and carbonaceous fiber residual carbon rate of 100
% Was calculated.

[0015]

Example 1 Gaseous carbon fine particles (Bellpearl C-800 manufactured by Kanebo Co., Ltd.) and powdered phenolic resin (Belpearl S-890 manufactured by Kanebo Co., Ltd.) were mixed at a ratio of 1: 4, and mixed with methyl ethyl ketone. A resin varnish prepared by dissolving it in a mixed solvent of 2-methoxyethanol (weight: 1: 1) to have a weight concentration of 42% was used as a carbon fiber woven fabric (manufactured by Kanebo Ltd .: C
3201), the solvent was removed in an oven, and then pre-cured to obtain a prepreg body. This prepreg body 12
After laminating the sheets and heating and molding at 150 ° C. for 60 minutes under a pressure of 30 kgf / cm ² with a hot press, the carbon fiber reinforced carbon composite material having a thickness of 8 mm is heated and carbonized to 1000 ° C. in a non-oxidizing atmosphere. Obtained. The bending strength of this C / C composite was 12.5 kg / cm ² , and the glassy carbon fine particles occupying the width of the C / C composite were Bellpearl S-8.
90 Carbide and carbon fiber weight ratio is 10:25:65
Met. Delamination did not occur in this C / C composite. Belpearl S-890 has a high residual carbon ratio of 65% compared to other liquid phenolic resins, and a dense C
/ C composite is obtained, so it is considered to be more effective.

[0016]

[Example 2] Example 1 except that a liquid phenol resin (BRL-274 manufactured by Showa High Polymer Co., Ltd.) was used instead of the powdery phenol resin Bellpearl S890 of Example 1.
A compounding treatment was carried out in the same manner as above to obtain a C / C composite.
The bending strength of this C / C composite is 11.0 kg / c.
m ² Glassy carbon fine particles The weight ratio of the carbide of the liquid phenol resin and the carbon fiber was 11:21:68.
Delamination did not occur in this C / C composite.

[0017]

[Example 3] Glass-like carbon fine particles were added to Belpearl C-
A carbon fiber-reinforced carbon composite material was obtained in exactly the same manner as in Example 1 except that the mixing ratio was 600 (Kanebo Co., Ltd.) and the mixing ratio with powdered phenol (Bellpearl S-870) was changed to 1:10. The bending strength of this C / C composite is 10.7.
Occupy in kg / cm ² C / C composite. The weight ratio of the glassy carbon fine particles, the bell pearl C-890 carbide, and the carbon fiber was 5:31:64. Delamination did not occur in this C / C composite.

[0018]

[Comparative Example] A carbon fiber reinforced carbon composite material was obtained in the same manner as in Example 1 from the powdery phenolic resin (Bellpearl S-890) and the carbon fiber woven fabric (C3201) without using glassy carbon fine particles. . The flexural strength of this C / C composite was 7.2 kg / cm ² , and the ratio of the carbide and carbon fiber of Belpearl S-890 in this C / C composite was 25:75. Gas blister and delamination occurred in this C / C composite.

[0019]

Comparative Example 2 Glassy carbon fine particles (Belpearl C-
800) and powdered phenolic resin ((Bellpearl S-8
90) and 7: 4 were mixed and dissolved in a mixed solvent of methyl ethyl ketone and 2-methoxyethanol in a weight ratio of 1: 1 to prepare a resin varnish having a weight concentration of 54%. A carbon fiber reinforced carbon composite material was obtained under the conditions. The weight ratio of the glassy carbon fine particles, the carbide of Bellpearl S-890, and the carbon fiber woven fabric in the C / C composite was 45:17:38. C / C obtained
Delamination did not occur in the composite, but the bending strength was as low as 5.2 kg / cm ² .

[0020]

Comparative Example 3 Glassy carbon fine particles (Belpearl C-
800) and powdered phenolic resin (Belpearl S-89
0) and 7) in a ratio of 7: 1 and dissolved in a mixed solvent of methyl ethyl ketone and 2-methoxyethanol in a weight ratio of 1: 1 to prepare a varnish having a weight concentration of 39%. A carbon fiber reinforced carbon composite material was obtained under the conditions.
The weight ratio of the glassy carbon fine particles, the carbide of Bellpearl S-890, and the carbon fiber woven fabric in the obtained C / C composite was 32: 3: 65. C / obtained
The C-composite was extremely brittle with a very low interlayer adhesion.

[0021]

Example 4 60 parts of PAN-based carbon fiber having a fiber length of 5 mm, 37 parts of Belpearl S890 and 16 parts of glassy carbon fine particles (C-800) were dispersed in water to prepare a sheet-like aggregate by a papermaking method. Ten of these were laminated to obtain a carbon fiber reinforced carbon composite material under the conditions of Example 1 below. The flexural strength of this C / C composite was 12.0 kg / cm ² , and no crack was observed. The weight ratio of the carbon fibers, the carbide of Belpearl S890, and the glassy carbon fine particles in the C / C composite was 60:24:16.

Claims (2)

[Claims] 1. A carbon fiber reinforced carbon composite material comprising a sintered resin carbonaceous matrix in which carbides of spherical or granular glassy carbon fine particles and non-graphitizable carbonaceous fibers are fixed. 2. A glassy carbon is prepared by forming an aggregate consisting of glassy carbon fine particles, a carbonizable resin and a carbonaceous fiber, press-molding the aggregate, and then firing and carbonizing the aggregate in a non-oxidizing atmosphere. 2 to 35 wt% of fine grain carbide
A method for producing a carbon fiber-reinforced carbon composite material, wherein the carbonaceous material derived from a resin is 5 to 50 wt% and the carbonaceous long fiber is 40 to 85 wt%.