JPH03109265A - Fiber reinforced carbonaceous composite material - Google Patents

Abstract

PURPOSE:To provide the above composite material which is excellent in strength, elasticity, toughness, etc., by using the specific high-strength and high- modulus inorg. fibers obtd. from a silicon-contg. polycyclic arom. polymer as a reinforcing material and a specific carbonaceous inorg. material as a matrix. CONSTITUTION:The fiber reinforced carbonaceous composite material is produced by using the high-strength and high-modulus inorg. fibers obtd. from the silicon-contg. polycyclic arom. polymer as the reinforcing material and the carbonaceous inorg. material obtd. from the silicon-contg. polyclic arom. polymer as the matrix. The constituting components of the inorg. fibers are the crystalline carbon derived from a polycyclic arom. compd. of a mesophase state constituting the polymer, the carbon in a non-oriented state derived from an optically isotropic polycyclic arom. compd. contg. the components insoluble in org. solvents constituting the polymer, and amorphous materials, etc., contg. Si, C, O, etc. The constituting components of the inorg. material are the crystalline carbon derived from the polycyclic arom. compd. constituting the polymer, amorphous carbon, and amorphous materials contg. Si, C, and O, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heat-resistant, wear-resistant carbonaceous inorganic composite material with excellent mechanical properties.

(Prior art and its problems) Among carbonaceous inorganic composite materials reinforced with inorganic fibers, so-called C/C composite materials using carbon fiber as the reinforcing fiber and carbon as the inorganic matrix have strength, specific elasticity, and non-oxidation properties. Excellent heat resistance, toughness, and friction properties in a harsh atmosphere,
It is promising as a heat-resistant structural material and brake material. Particularly in brake applications, practical use is progressing for aircraft and racing cars.

However, C/C composites tend to cause fatal cracks and peeling at the interface between the reinforcing material and matrix carbon, making it difficult to obtain sufficient mechanical strength. However, it is difficult to use it for a long time in an oxidizing atmosphere, and although it has excellent friction properties and lubricity, its wear resistance is not necessarily sufficient.

In order to improve this drawback and improve the interfacial adhesion between carbon fibers and matrix carbon, methods have been used in which the surface of carbon fibers is sized with various treatment agents and coated with methods such as CVD. There is.

However, with the above sizing method, it is difficult to fundamentally solve the problem of interfacial adhesion between carbon fibers and matrix carbon, and new defects and peeling occur between the treatment agent and the fibers or matrix. Some agents may remain as impurities in the composite material, resulting in loss of corrosion resistance, heat resistance, etc. among the excellent properties of the C/C composite.

On the other hand, the method of coating each fiber is
It is necessary to add a process with low productivity such as a CVD process, which makes the composite material expensive, and the fiber diameter of the obtained fiber increases, which causes a loss of flexibility and freedom in composite material design. This was a significant reduction in severity.

On the other hand, when amorphous inorganic fibers such as silicon carbide fibers are used as reinforcing fibers, the adhesion of the reinforcing fibers to the carbon matrix is improved; could not be retained sufficiently, so it was not possible to improve the mechanical properties of the composite material.

On the other hand, as a method for improving the oxidation resistance and abrasion resistance of matrix carbon, Am, Ceram, So'c, Bu
Walker (
B., E. Walker, Jr.) describe a method in which a C/C composite is impregnated with an organosilicon polymer and then thermally decomposed to introduce a silicon carbide component into the matrix. The bending strength of the composite material is as low as 15 BMP.

Also, Proc, of Int, Symp, on C
eramic, Compon.

for Engine, 1983+Japan, p50
In 5, Fitzer et al.
This paper describes a method in which a C/C composite is impregnated with a silicon melt to convert the matrix into silicon carbide, but the resulting composite material is made up of metal silicon that remains unreacted between the matrix particles. , creep metamorphosis occurs at high temperatures of 1300°C or higher, and it does not have the high-temperature properties of C/C composites.

In addition to the conventional complicated C/C composite manufacturing process, each of the above-mentioned processes involves an additional complicated process, making it difficult to use industrially.

(Means for Solving the Problems) An object of the present invention is to provide a novel inorganic fiber-reinforced carbon material that solves the above problems.

Another object of the present invention is to provide an inorganic fiber-reinforced carbon material with excellent mechanical properties.

Another object of the present invention is to provide a carbon material with excellent corrosion resistance, heat resistance, and oxidation resistance.

The inorganic fiber-reinforced carbonaceous composite material of the present invention is a composite material having inorganic fibers as a reinforcing material and an inorganic substance as a matrix, wherein the inorganic fibers are inorganic fibers obtained from a silicon-containing polycyclic aromatic polymer. and its constituent components are t) Consisting of a radial structure, an onion structure, a random structure, a core radial structure, a skin onion structure, and a mosaic structure derived from the polycyclic aromatic compound in the mesophase state that constitutes the E'A polymer. ii) a non-oriented crystalline substance derived from an optically isotropic polycyclic aromatic compound containing an organic solvent insoluble component constituting the polymer; carbon and/or amorphous carbon, and 1ii) an amorphous phase consisting essentially of St, C and 0 and/or crystalline ultrafine particles consisting essentially of β-SiC with a particle size of 500 Å or less and amorphous It is an aggregate consisting of quality SiOx (0<x≦2), and the ratio of constituent elements is S i ; 3
0-70% by weight, C; 20-60% by weight and O; 0.
A high-strength, high-modulus inorganic fiber made of a Si-C-0 material of 5 to 10% by weight, wherein the inorganic material is an inorganic material obtained from a metal-containing polycyclic aromatic polymer, and its constituent components is a) crystalline carbon derived from a polycyclic aromatic compound in a mesophase state constituting the polymer, or crystalline carbon and amorphous carbon, b) optically isotropic carbon constituting the 31 polymer. non-oriented crystalline carbon and/or amorphous carbon derived from a polycyclic aromatic compound; and c) (1) an amorphous substance consisting essentially of Si, M, C and 0; and/or ■Substantially β-SiC, MC1 It is an aggregate of crystalline ultrafine particles with a particle size of 500 Å or less consisting of a solid solution of β-SiC and MC and MCI-X, and amorphous SiOy and MO□, and its constituent elements The proportion of Si: 5 to 70% by weight, M: 0.5 to 70% by weight
45% by weight, C: 20-40% by weight and O: 0.01-
30% by weight of Si-M-C-〇 material (in the above formula, M
is a carbonaceous inorganic substance consisting of a small amount selected from Ti, Zr, and Hf (all of which are one type of element, and Q<x<1, O<y≦2, and Q<z≦2).

First, the inorganic fiber in the present invention will be explained in detail. In the following explanation, "part" means "part by weight" and "%
” is “% by weight”.

The inorganic fibers in the present invention include the above-mentioned constituent components i), i)
Consisting of i) and ji), St; 0.01 to 29
%, C, 70-99.9% and o, o, o.

1-10%, preferably Si; 0.1-25%, C; 7
4 to 99.8% and O; 0.01 to 8%.

Crystalline carbon, which is a component of this inorganic fiber, has a crystallite size of 500 Å or less, and is oriented in the fiber axis direction in a high-resolution electron microscope with a resolution of 1.5 people.
It is an ultrafine graphite crystal in which a fine lattice image corresponding to two (002) planes can be observed.

The crystalline carbon in the inorganic fibers can have a radial structure, an onion structure, a random structure, a core radial structure, a skin onion structure, a mosaic structure, a random structure including a partial radial structure, and the like. This is due to the presence of the mesophase polycyclic aromatic compound (2) in the raw material.

Total sum of constituent components i) and ii) in this inorganic fiber 1
The ratio of component 1ii) to 0.00 parts is from 0.015 to
200 parts, and the ratio of components i) and ii) is 1
:0.02-4.

When the ratio of component 1ii) to 100 parts of the total of components i) and ii) is less than 0.015, the fiber is almost the same as pitch fiber, and the oxidation resistance and interfacial adhesive strength with the matrix are not improved. If the above ratio exceeds 200 parts, graphite fine crystals will not be effectively generated.
Fibers with high elastic modulus cannot be obtained.

In the continuous inorganic fiber of the present invention, microcrystals with a small interlayer spacing and three-dimensional arrangement are effectively generated,
Silicon atoms are distributed very uniformly so as to surround the microcrystals.

The inorganic fiber in the present invention includes: 1) a bonding unit (St CH2) or a bonding unit (Si
Hz) and a bonding unit (Si-3t),
Having a side chain group selected from the group consisting of a hydrogen atom, a lower alkyl group, a phenyl group and a silyl group in the side chain of a silicon atom,
Bonding unit (Si-CH2) (7) Total number of pairs bonding unit (St
-3i) (7) At least a part of the silicon atoms of the organosilicon polymer whose total number ratio is in the range of 100 to 20 are bonded to the carbon of the aromatic ring of petroleum-based or coal-based pitch or its heat-treated product. 100 parts of a precursor polymer and 2) a mesophase state obtained by heat-treating petroleum-based or coal-based pitch, or a polycyclic aromatic compound consisting of both mesophase and optically isotonic phase (hereinafter both are collectively referred to as "
Sometimes referred to as ``mesophase polycyclic aromatic compounds''.

) 5 to 50,000 parts are heat-reacted and/or heat-melted at a temperature in the range of 200 to 500°C to obtain a silicon-containing polycyclic aromatic polymer.
a second step of preparing a spinning dope of the silicon-containing polycyclic aromatic polymer and spinning it; a third step of infusibleizing the spun yarn under tension or without tension;
and a fourth step of firing the infusible spun fiber bundle at a temperature in the range of 800 to 3000° C. in vacuum or in an inert gas atmosphere.

Each of the above steps will be explained in more detail.

First step: The organosilicon polymer, which is one of the starting materials, can be synthesized by a known method. For example, polymethylsilane obtained by the reaction of dimethyldichlorosilane and metallic sodium is heated in an inert gas for 400 min. Obtained by heating above °C.

The organosilicon polymer has a bonding unit (Si CHt),
Or the bonding unit (St CHz) and the bonding unit (3i-S
i), and the ratio of the total number of bond units (St-CH,) to the total number of bond units (Si-3i) is 100 to 2
It is within the range of 0.

The weight average molecular weight (MW) of the organosilicon polymer is 300 to 1000 for boat fishing, and those with Ml of 400 to 800 are suitable for use as precursor polymers (which are intermediate raw materials for obtaining excellent carbon-based inorganic fibers). Particularly preferred for preparing 1).

Another starting material, a polycyclic aromatic compound, is pitch obtained from petroleum and/or coal, especially heavy oil obtained by fluid catalytic cracking of petroleum, and pitch obtained by distilling the heavy oil. Distillate components or residual oils and pitch obtained by heat-treating them.

The above pitch contains 5 to 9 components insoluble in organic solvents such as benzene, toluene, xylene, and tetrahydrofuran.
The content is preferably 8% by weight. If pitch containing less than 5% by weight of the above-mentioned insoluble components is used as a raw material, inorganic fibers with excellent strength and elastic modulus cannot be obtained;
If more than % by weight of pitch is used as a raw material, the molecular weight of the copolymer will increase sharply, and coking may occur in some cases, making spinning difficult.

The weight average molecule N (Mt, ) of this pitch is 100
~3000.

The weight average molecular weight is a value determined as follows. That is, if the pitch does not contain organic solvent insoluble components for gel permeation chromatography (GPC) measurement, such as benzene, toluene, xylene, tetrahydrofuran, chloroform, and dichlorobenzene, the pitch is directly measured by GPC, and the pitch is determined from the above organic solvent insoluble components. If it contains, it is hydrogenated under mild conditions to change the organic solvent-insoluble components to the organic solvent-soluble components, followed by GPC measurement. The weight average molecular weight of the polymer containing the organic solvent insoluble matter is a value obtained by performing the same treatment as above.

Precursor polymer (1) is prepared by adding petroleum-based or coal-based pitch to an organosilicon polymer, and preparing the mixture preferably at 250% in an inert gas.
It is prepared by a heated reaction at a temperature in the range of ~500''C.

The ratio of pitch used is 8 parts per 100 parts of organosilicon polymer.
It is preferable that it is 3-4900 parts.

If the ratio of pitch used is too small, the silicon carbide component in the resulting inorganic fiber will increase, making it impossible to obtain an inorganic fiber with a high modulus of elasticity. As a result, inorganic fibers with excellent interfacial adhesion with matrix carbon and oxidation resistance cannot be obtained.

If the reaction temperature of the above reaction is too low, it will be difficult to form bonds between silicon atoms and aromatic carbon, and if the reaction temperature is too high, the resulting precursor polymer (1) will be violently decomposed and its molecular weight will increase. Undesirable.

The mesophase polycyclic aromatic compound (2) is, for example, petroleum-based or coal-based pitch heated to 300 to 500% in an inert gas.
Q can be carried out by heating to °C and performing condensation polymerization while removing the soft fraction produced.

If the temperature of the condensation polymerization reaction is too low, the growth of the condensed ring will not be sufficient, and if the temperature is too high, an insoluble or infusible product will be produced due to coking.

The mesophase polycyclic aromatic compound (2) has a melting point of 20
The temperature is in the range of 0 to 400°C, and the weight average molecular weight is in the range of 200 to 10,000.

Among the mesophase polycyclic aromatic compounds (2), 20
Those having an optical anisotropy of 100% to 100% and containing 30 to 100% insoluble matter in benzene, toluene, xylene or tetrahydrofuran are particularly preferred in order to obtain inorganic fibers with excellent mechanical performance.

In the first step, the precursor polymer (1) and the mesophase polycyclic aromatic compound (2) are heated and melted and/or reacted in a temperature range of 200 to 500°C to form a silicon-containing polycyclic aromatic polymer. Prepare the spun polymer.

The mesophase polycyclic aromatic compound (2) is preferably used in an amount of 5 to 50,000 parts per 100 parts of the precursor polymer (1). If it is less than 5 parts, the mesophase content in the product will be insufficient, resulting in high elasticity. If the amount is more than 50,000 parts, an inorganic fiber with excellent interfacial adhesion with matrix carbon and oxidation resistance cannot be obtained due to the lack of silicon component.

The weight average molecular weight of the silicon-containing polycyclic aromatic polymer is 2
00-11000, and the melting point is 200-400°C.

2nd step: The spinning polymer, which is a silicon-containing polycyclic aromatic polymer obtained in the 1st step, is heated and melted, and in some cases, it is filtered to remove substances that are harmful during spinning, such as microgels and impurities. This is then spun using a commonly used synthetic fiber spinning device.

The temperature of the spinning dope during spinning varies depending on the softening temperature of the raw material polymer, but a temperature in the range of 220 to 420°C is advantageous.

In the spinning device, a spinning tube is attached as necessary, and the atmosphere inside the spinning tube is changed to air, inert gas, hot air,
After creating an atmosphere of one or more selected from the group consisting of thermally inert gas, steam, and ammonia gas, fibers with a narrow diameter can be obtained by increasing the winding speed. The spinning speed in the melt spinning varies depending on the average molecular weight, molecular weight distribution, and molecular structure of the raw materials, but is 50 to 50%.
000 m/min is preferable.

Third step: The spun fibers obtained in the second step are made infusible under the action of tension or no tension.

A typical method for infusibility is to heat the molded article in an oxidizing atmosphere. The infusibility temperature is preferably 50 to 4
The temperature is in the range of 00'C. If the infusibility temperature is too low, the polymer constituting the matrix will not deform, and if the temperature is too high, the polymer will burn.

The purpose of infusibility is to make the polymer that makes up the spun fibers into a three-dimensional structure that is infusible and insoluble, so that it does not melt during the next firing process and does not fuse with adjacent fibers. It is. Gases constituting the oxidizing atmosphere during infusibility include air, ozone, oxygen, chlorine gas, bromine gas, ammonia gas, and mixed gases thereof.

As an infusibilization method different from the above, the spun fibers are infusibilized by irradiation with gamma rays or electron beams in an oxidizing or non-oxidizing atmosphere, under tension or without tension, while heating at a low temperature as necessary. method can also be adopted.

The purpose of irradiating with gamma rays or electron beams is to further polymerize the polymer that forms the spun fibers.
The purpose is to prevent the spun yarn from melting and losing its fiber shape.

The appropriate dose of γ-rays or electron beams is 10' to 1010 rand.

Irradiation can be carried out in a vacuum, an inert gas atmosphere, or an oxidizing gas atmosphere such as air, ozone, oxygen, chlorine gas, bromine gas, ammonia gas, and mixtures thereof.

Infusibility by irradiation can be carried out at room temperature, and if necessary, infusibility can be achieved in a shorter time by heating in the temperature range of 50 to 200°C.

If infusibility is carried out without tension, the spun fibers will shrink and take on a wavy shape, but this can sometimes be corrected in the next firing process, and tension is not necessarily required. In this case, good results can be obtained by applying a tension that is small enough to prevent the spun fibers from shrinking and becoming wavy during infusibility.

The tension to be applied during infusibility is 1 to 500
A range of 7mm" is preferable; even if a tension of 1g7mm2 or less is applied, it will not be possible to apply enough tension to prevent the fibers from sagging; if a tension of 500g7mm2 or more is applied, the fibers may break. .

Fourth step: By firing the infusible yarn obtained in the third step at a temperature in the range of 800 to 3000°C in a vacuum or inert gas atmosphere, inorganic fibers mainly composed of carbon, silicon, and oxygen are obtained. It will be done.

In the firing process, it is not necessarily necessary to apply tension, but high-temperature firing while applying tension in the range of 0, 00 to 100 Kg/mm" makes it possible to obtain high-strength inorganic fibers with less bending.

It is estimated that during the heating process, mineralization becomes intense from about 700°C and is almost completed at about 800°C. Therefore, the firing is preferably performed at a temperature of 800°C or higher. Furthermore, since obtaining a temperature higher than 3000°C requires expensive equipment, firing at a higher temperature than 3000°C is not practical from a cost standpoint.

The distribution state of silicon in the inorganic fiber of the present invention can also be controlled by the atmosphere during firing and the size and concentration of mesophase in the raw material. For example, when the mesophase is grown to a large size, the silicon-based polymer is easily extruded into the fiber surface phase, and a silicon-rich layer can be formed on the fiber surface after firing.

Incidentally, the constituent component of the inorganic fiber is Si-C
The form of the -0 substance can be controlled by the mineralization temperature in the fourth step.

When it is desired to obtain an amorphous substance consisting essentially of Si, C, and 0, it is preferable to set the mineralization temperature to 800 to 1000'C, and to obtain an amorphous substance consisting essentially of β-SiC and amorphous SinX (however, When it is desired to obtain O<x≦2), a temperature of 1700°C or higher is suitable.

Further, when a mixed system of each aggregate is desired, the temperature can be appropriately selected from the above intermediate temperatures.

Further, the amount of oxygen in the inorganic fiber of the present invention can be controlled, for example, by the infusibility conditions in the fourth step.

Next, a method for producing a metal-containing polycyclic aromatic polymer, which is a raw material for the matrix of the fiber-reinforced carbonaceous composite material of the present invention, will be explained.

The metal-containing polycyclic aromatic polymer has 1) a bonding unit (Si CHz) or a bonding unit (S
i CHz) and a bonding unit (St-3i), and has a hydrogen atom, a lower alkyl group, a phenyl group, or a silyl group in the side chain of silicon, and the silicon atom of the main skeleton consisting of the bonding unit has Ti , Zr, and Hf are bonded directly or via oxygen atoms. The heat-treated product is a random copolymer (3) bonded to the carbon of the aromatic ring of a polycyclic aromatic compound obtained from pitch containing organic solvent-insoluble matter and (2) petroleum-based or coal-based pitch. It is produced by heating reaction and/or heating melting of the obtained mesophase or a polycyclic aromatic compound consisting of both the mesophase and the optically auspicious phase at a temperature in the range of 200 to 500°C.

The random copolymer (3) is produced by reacting the precursor polymer (1) produced in the first step of producing inorganic fibers with a transition metal compound represented by MX4 at a temperature of 100 to 500°C. Prepare. Note that since the metal-containing polycyclic aromatic polymer is not required to be made into fibers, the composition ratio of silicon and carbon may be set to a somewhat wider range than in the case of producing the inorganic fibers. That is, the proportion of pitch used in the production of the precursor polymer (1) is:
It is preferably 10 to 4900 parts per 100 parts of organosilicon polymer.

In the above-mentioned MX, M is a small amount selected from Ti, Zr, and Hf (both are one type of element, and X is a type of element selected from Ti, Zr, and Hf, and Any substance that can be bonded may be used, and although there is no particular limitation, a halogen atom, an alkoxy group, or a complex-forming group such as β-diketone is preferable.

If the reaction temperature is too low, the precursor polymer (1) and 2MX4
If the condensation reaction with M does not proceed and the reaction temperature is excessively high, M
Preferably, the crosslinking reaction of the precursor polymer (1) may proceed excessively and cause gelation, or the precursor polymer (1) itself may condense and increase its molecular weight, or in some cases, MX may volatilize. do not have. - For example, when M is Ti and X is OC4Hq, a suitable reaction temperature is 200-400°C.

Through this reaction, a random copolymer (3) in which at least some of the silicon atoms of the precursor polymer (1) are bonded to the metal M directly or via oxygen atoms is prepared.

The metal M can be bonded to the silicon atom of the precursor polymer (1) in the form of a side chain in a bonding mode such as -M Alternatively, a bonding mode such as crosslinking via oxygen may be adopted.

As a method for preparing the random copolymer (3), in addition to the above-mentioned method, it is also possible to prepare the random copolymer (3) by reacting an organosilicon polymer with MX and further reacting the resulting product with pitch. .

A metal-containing polycyclic aromatic polymer is prepared by subjecting the random copolymer (3) and the mesophase polycyclic aromatic compound produced in the first step of producing inorganic fibers to a heating reaction and/or heating and melting.

The proportion of the mesophase polycyclic aromatic compound to be used is preferably 5 to 50,000 parts per 100 parts of the random copolymer (3); if it is less than 5 parts, the mesophase content in the resulting polymer will be insufficient. Even if the resulting polymer is mineralized, highly elastic fibers or molded products cannot be obtained.
If the amount is more than 50,000 parts, the silicon component is insufficient, and even if the polymer is made inorganic, its properties such as matrix wettability and oxidation resistance cannot be sufficiently exhibited.

By heating the random copolymer (3) and the mesophase polycyclic aromatic compound at 200 to 500°C and/or heating and melting it, at least a part of the random copolymer (3) becomes a mesophase polycyclic aromatic compound. A metal-containing polycyclic aromatic polymer combined with a compound is obtained. However, the bond mentioned here refers to the chemical bond between silicon and carbon of the polycyclic aromatic compound and/or the bond between the optically isotropic pitch part in the random copolymer (3) and the mesophase polycyclic aromatic compound. It means a physical bond such as a van der Waals bond between.

If the above-mentioned melt mixing temperature is lower than 200°C, an infusible portion will occur and the system will become non-uniform;
If the temperature is higher, the condensation reaction will proceed violently, the resulting polymer will have a high melting point, and the fluidity of the polymer will be lost.As a method for preparing a metal-containing polycyclic aromatic polymer,
In addition to the above-mentioned method, it is also possible to prepare a product by reacting an organosilicon polymer and pitch, adding mesophase pitch and MX simultaneously or sequentially to the resulting product, and further reacting.

Next, a method for manufacturing the fiber-reinforced carbonaceous composite material of the present invention will be explained.

First, a method of adding powder of the metal-containing polycyclic aromatic polymer to various textiles such as plain weave, satin weave, mock-sawn weave, twill weave, spiral weave, three-dimensional weave, etc. of the inorganic fibers and hot pressing to form the said textile; A method of impregnating a solution or slurry of a metal-containing polycyclic aromatic polymer, removing the solvent, and heat-forming a dried prepreg sheet; The combined product is melt-kneaded and a fiber-containing molded article is produced by press molding, injection molding, or the like. At that time, the content of inorganic fibers in the molded body is preferably 10 to 70% by volume.

In addition, in producing a fiber-containing molded article, a calcined powder obtained by calcining and mineralizing this polymer at 800 to 1000°C in an inert gas atmosphere is mixed with the metal-containing polycyclic aromatic polymer. However, there is no harm in using it.

This calcined body powder contains Si: 0.01 to 69.9%, M
: 0.005-30.0%, C: 29.9-99.9
% and o: It is preferable that it substantially consists of o, oo i to 10%.

Next, the molded body is subjected to an infusible treatment, if necessary.

As the method of infusibility treatment, the method of the third step of inorganic fiber production can be directly adopted.

The infusible molded body is heated in vacuum or inert gas,
Calcined at temperatures in the range 800-3000° C., a mineralized, fiber-reinforced composite material with a matrix of carbon, silicon, M and oxygen is obtained.

It is estimated that during the heating process, mineralization becomes intense from about 700°C and is almost completed at about 800°C. Therefore, the firing is preferably performed at a temperature of 800°C or higher. Furthermore, since obtaining a temperature higher than 3000°C requires expensive equipment, firing at a higher temperature than 3000°C is not practical from a cost standpoint.

Note that the infusibility step can be omitted by extremely slowing down the temperature increase rate for mineralization in this step, or by using a shape-retaining means such as a molded object shape-retaining jig or a powder head. It is also possible to obtain a high-density composite material in one step by using high-temperature hot pressing as a molding method.

Since the fiber-reinforced carbonaceous composite material obtained by calcination and mineralization contains open pores to some extent, it may be impregnated with the melt, solution or slurry of the metal-containing polycyclic aromatic polymer, if necessary. By making it infusible, firing it, and making it inorganic, it is possible to increase the density and strength of the composite.

Impregnation can be carried out using either a melt, solution or slurry of the metal-containing polycyclic aromatic polymer; After impregnating, promote penetration into the fine pores under reduced pressure, and then raise the temperature while distilling off the solvent to produce 10 to 500 kg/
The pores are filled with the polymer melt by applying pressure to .tin''.

The obtained impregnated body is made infusible in the same manner as in the third step,
Can be calcined and mineralized. Repeat this operation 2 to 10 times
By repeating this process several times, a fiber-reinforced composite material with high density and high strength can be obtained.

(Effects of the Invention) The fiber-reinforced carbonaceous composite material of the present invention has high strength, high elasticity, and improved adhesion with the carbon matrix, so the reinforcing fibers have high strength, high elasticity, and excellent toughness. A carbonaceous composite material can be obtained. Further, due to the effects of the silicon carbide component and the titanium carbide component contained in the fibers and matrix, a material with excellent oxidation resistance and wear resistance can be obtained.

Therefore, the obtained composite material has excellent mechanical properties, oxidation resistance, and abrasion resistance, and is excellent as a heat-resistant structural material for various types of brakes.

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

Reference Example 1 (Production of Polymer I) Anhydrous xylene 2. Si and 400 g of sodium were put therein, heated under a nitrogen gas stream to the boiling point of xylene, and 1 liter of dimethyldichlorosilane was added dropwise over 1 hour. After the dropwise addition was completed, the mixture was heated under reflux for 10 hours to form a precipitate. The precipitate was filtered and washed with methanol and then water to obtain 420 g of white powder polydimethylsilane.

400 g of this polydimethylsilane was charged into a 31-hole flask equipped with a gas inlet tube, a stirrer, a condenser, and a distillation tube, and heated at 420 degrees under a nitrogen flow of 50 mm/min while stirring.
C. to obtain 350 g of a colorless and transparent slightly viscous liquid in a distillation receiver.

The number average molecular weight of this liquid was 470 as measured by vapor pressure osmosis.

When the infrared absorption spectrum of this substance was measured, it was found that 6
SiCH3 at 50~900cm-' and 1250cm-'
Absorption of Si-H at 2100 cm-', 1020
Si CHzSi near cm-' and 1355 cm-'
absorption, C at 2900c111-summer and 2950cm-'
-H absorption was observed, and when the far infrared absorption spectrum of this material was measured, Si-3
Since absorption of i is observed, the obtained liquid substance is
Mainly (St CH2) bonding units and (Si-3i
) was found to be an organosilicon polymer consisting of bonding units and having hydrogen atoms and methyl groups in silicon side chains.

From the measurement results of nuclear magnetic resonance analysis and infrared absorption analysis, this organosilicon polymer is a polymer in which the ratio of the total number of (Si CHI) bond units to the total number of (Si-Si) bond units is approximately 1:3. This was confirmed.

300 g of the above organosilicon polymer was treated with ethanol to remove low molecular weight substances to obtain 40 g of a polymer having a number average molecular weight of 1200.

When we measured the infrared absorption spectrum of this substance, absorption peaks similar to those above were observed, and this substance mainly consists of (S1-CH,) bond units and (Si-3i) bond units, and It turned out to be an organosilicon polymer containing hydrogen atoms and methyl groups.

According to the measurement results of nuclear magnetic resonance analysis and infrared absorption analysis, this organosilicon polymer is a polymer in which the ratio of the total number of (Si CH2) bond units to the total number of (Si-3i) bond units is approximately 7:1. This was confirmed.

On the other hand, among petroleum fractions, substances with a boiling point higher than that of light oil are removed using silica.
Fluid catalytic cracking and rectification were performed at a temperature of 500°C in the presence of an alumina-based cracking catalyst, and a residue was obtained from the bottom of the column. Hereinafter, this residue will be referred to as FCC slurry oil.

As a result of elemental analysis, this FCC slurry oil had an atomic ratio of carbon atoms to hydrogen atoms (C/H) of 0675, and an aromatic carbon ratio of 0.55 as determined by nuclear magnetic resonance analysis.

200g of the above FCC slurry oil was added to nitrogen gas.

After heating to 450 °C under air flow and distilling off the distillate at the same temperature, the residue was filtered while hot at 200 °C to remove the infusible part at the same temperature, and 57 g of light bone-removed Bi-Sochi was obtained. I got it.

This light bone removal pitch contained 25% xylene insolubles.

Add 25 g of organosilicon polymer and 20 mm of xylene to 57 g of this light bone-removed pitch, raise the temperature while stirring, distill off the xylene, and react at 400°C for 6 hours to obtain Sig precursor polymer (1). Ta.

As a result of infrared absorption spectrum measurement, this precursor polymer (1) was found to have Si-H bonds (IR:
2100cm-') and the formation of a new Si-C (benzene ring carbon) bond (IR: 1135C11-'), some of the silicon atoms in the organosilicon polymer were found to be polycyclic aromatic rings. It was found that it is a copolymer with a portion directly bonded to carbon.

This precursor polymer (1) contained no xylene-insoluble portion, had a weight average molecular weight of 1400, a melting point of 265°C, and a softening point of 310°C.

On the other hand, 180 g of the light bone-removed pitch was subjected to condensation polymerization at 400° C. for 8 hours under a nitrogen stream while removing light bones produced by the reaction to obtain heat-treated pinch 97.2.

This heat-treated pitch has a melting point of 263°C and a softening point of 308°C.
It was a mesophase polycyclic aromatic compound containing 77% xylene-insoluble matter and 31% quinoline-soluble matter, and had an optical anisotropy of 75% when observed with a polarizing microscope on the polished surface.

90 g of this mesophase polycyclic aromatic compound and 6.4 g of the precursor polymer (1) were mixed at 380°C under a nitrogen atmosphere.
The mixture was melted and heated for 1 hour to obtain a silicon-containing polycyclic aromatic polymer in a uniform state.

The melting point of this polymer is 267°C and the softening point is 315°C.
It contained 70% xylene insoluble matter.

Reference Example 2 (Production of Polymer ■) A silicon-containing polycyclic aromatic compound was prepared in the same manner as in Reference Example 1, except that 97 g of the mesophase polycyclic aromatic compound and 3 g of the precursor polymer (1) were mixed and melted and heated at 400"C. A family polymer was obtained.

The melting point of this polymer is 272°C (and the softening point is 319°C).
It contained 71% xylene insoluble matter.

Reference Example 3 (Production of Polymer ■) A xylene solution (15.5 g of 25% xylene solution) of 3.87 g of tetraoctoxytitanium (T i (OCs H17) 4) was added to 57.4 g of precursor polymer (1). In addition, after xylene was distilled off, the mixture was reacted at 340°C for 1 hour to obtain 56 g of random copolymer (2).

The obtained random copolymer (2) and the mesophase polycyclic aromatic compound obtained in Reference Example I were melt-mixed at a ratio of 1:1 at 380°C under a nitrogen atmosphere to produce Polymer (2).

Reference Example 4 (Production of Polymer ①) To 39 g of the precursor polymer obtained in Reference Example 1, an ethanol-xylene solution (1.5%) of 5.4 g of tetrakis acetylacetonatosilconium was added, and after distilling off the xylene,
Polymerization for 1 hour at °C yielded 39.5 g of random copolymer (
2) was obtained.

The obtained random copolymer (2) and the mesophase polycyclic aromatic compound obtained in Reference Example 1 were melt-mixed at a ratio of 1:1 at 380°C under a nitrogen atmosphere to produce Polymer (2).

Reference Example 5 (Production of Polymer (1)) 57 g of a precursor polymer was obtained in the same manner as in Example 1, except that the amounts of light bone removal pitch and organosilicon polymer used were changed to 60 g and 40 g, respectively.

An ethanol-xylene solution (1.5%) of 7.2 g of hafnium chloride was added to 40 g of this precursor polymer (1), and after the xylene was distilled off, polymerization was carried out at 250 °C for 1 hour.
5 g of random copolymer (2) was obtained.

The obtained random copolymer (2) and the mesophase polycyclic aromatic compound obtained in Reference Example 1 were melt-mixed at a ratio of 1:1 at 380° C. under a nitrogen atmosphere to produce Polymer (1).

Reference Example 6 (Manufacture of inorganic fiber) Using the polymer (1) obtained in Reference Example 1 as a raw material for spinning, melt spinning was performed at 360°C using a metal nozzle with a nozzle diameter of 0.15 am, and the obtained spun yarn was obtained. , in air at 300℃
oxidized and made infusible, and then heated at 1300°C in an argon atmosphere.
The fibers were fired to obtain inorganic fibers (2) with a diameter of 8 μm.

This fiber had a tensile strength of 320 kg/m'' and a tensile modulus of 26 t/mm'', and an observation of the fractured surface using a scanning electron microscope clearly showed a radial structure.

After pulverizing the inorganic fiber I, it was melted with alkali and treated with hydrochloric acid to form an aqueous solution, which was then subjected to high-frequency plasma emission spectrometry analysis (I
CP), the silicon content was 0.95%.

Polymer (2) obtained in Reference Example 2 was spun and infusible in the same manner as above, and then fired at 2500°C in an argon atmosphere to obtain inorganic fiber (2) with a diameter of 7.2 μm.

The tensile strength of this fiber was 335) cg/mm'', and the tensile modulus was 53 t/mm''.

After pulverizing this inorganic fiber, it was melted with alkali and treated with hydrochloric acid to form an aqueous solution, which was then analyzed by high-frequency plasma emission spectroscopy (1,
CP), the silicon content was 0.42%.

Reference Example 7 (Manufacture of silicon carbide fiber) The silicon carbide fiber obtained only from polycarbosilane used in Comparative Example 2 was manufactured as follows.

3 parts by weight of polyborosiloxane was added to 100 parts by weight of polydimethylsilane synthesized by dechlorination condensation of dimethyldichlorosilane with metallic sodium, and 350 parts by weight of polyborosiloxane was added in nitrogen.
Thermal condensation was carried out at °C to obtain a polycarbosilane having a main chain skeleton mainly composed of carbosilane units of the formula (Si-CH2) and having a hydrogen atom and a methyl group on the silicon atom of the carbosilane unit. . This polymer is melt-spun,
Infusibility treatment was carried out at 190°C in air, followed by firing at 1300°C in nitrogen, resulting in a fiber diameter of 13μ, tensile strength of 300 Kg/mm, and tensile modulus of 16t/Inf.
A silicon carbide fiber consisting mainly of silicon, carbon and oxygen was obtained.

Example 1 The two-dimensional plain woven fabric of the inorganic fiber r obtained in Reference Example 6 had a diameter of 7 cm.
It was cut into discs of 500 m in diameter, impregnated in a 30% xylene slurry of polymer (1), and dried to produce prepreg sheets. In the mold, fill the spaces between the prepreg sheets with fine powder of polymer ①, and set the fiber direction of the reinforcing fibers to 45.
Thirty sheets were laminated while being shifted sequentially by .degree., and hot-pressed at 350.degree. C. under pressure of 50 kg/d to obtain a disc-shaped molded product.

This molded body was buried in a powder bed of carbon powder to maintain its shape, and the temperature was raised to 800°C at a rate of 5°C/h in a nitrogen stream, and then further raised to 1300°C to inorganize the matrix. The bulk density of the obtained composite material was 1.19 g/cd.

This composite material was immersed in a 50% xylene slurry of polymer Ⅰ, heated to 350°C while distilling off the xylene under reduced pressure, then impregnated at a pressure of 100 kg/cJ, and then heated at 5°C/h in air. The temperature was raised to 300°C at a high speed to make it infusible and then mineralized at 1300''C. This impregnation and mineralization treatment was repeated three more times to obtain a material with a bulk density of 1.96 g LC. The bending strength of the composite material was 57 kg.
/mm”.

Example 2 A mixture of 50 parts of an inorganic material calcined in nitrogen at 1300°C and 50 parts of powder of polymer ■ and a two-dimensional plain woven fabric of the inorganic fiber ■ obtained in Reference Example 6 were alternately mixed. and hot pressed at 400°C and 1100kg/c4 to obtain a molded body. This molded body was mineralized in the same manner as in Example 1, and the impregnation and mineralization were repeated four more times in the same manner as in Example 1 using Polymer (1). The obtained composite material had a bulk density of 2.03 g/ci and a bending strength of 58 kg/mm2. When this composite material was further fired at 2200'C in argon, the bulk density was 2.06 g/ci, The bending strength was improved to 63 kg/Peng2.

Example 3 A composite material was obtained in the same manner as in Example 1 except that Polymer (2) of Reference Example 5 was used as the prepreg sheet manufacturing polymer, mold filling polymer, and impregnation polymer. The bulk density of the obtained composite material is 2. IOg/ci, bending strength 54kg
/in2.

Comparative Example 1 As reinforcing fibers, commercially available PAN-based carbon fibers with a fiber diameter of 7 μm, a tensile strength of 300 kg/+nm", and a tensile modulus of 21 t 7 mm" were used instead of the inorganic fibers of Reference Example 6, and instead of the polymer A carbon fiber-reinforced carbon material was obtained in the same manner as in Example 1 using petroleum-based heat-treated pitch with a softening point of 150°C and a residual carbon content of 60%. This material has a low bulk density of 1.67 g/cm and a bending strength of 15 kg/m.
It was "m".

Comparative Example 2 Using the silicon carbide fibers obtained in Reference Example 7, a matrix was prepared using an equal weight mixture of artificial graphite with a bulk density of 0.15 g/cJ when no load was applied and powder with the same pitch as that used in Comparative Example 1. As in Example 2, the raw material was made into a molded body by hot pressing, mineralized, and then impregnated with the pitch and mineralized four times, resulting in a bulk density of 1.90 g/ci. , bending strength is 21kg/a+m
” composite material was obtained.

Graphitization of this composite material at 2200'C was attempted, but the reinforcing fibers deteriorated and the strength decreased to 5 kg/mm''.

Example 4 The composite materials of Example 1.2.3 and Comparative Example 1.2 were
The bending strength was measured after heat treatment for 1 hour in an oven in an air atmosphere of C.

The composite material of Comparative Example 1.2 had undergone oxidative deterioration to such an extent that its strength could not be measured, but the composite material of Example 1.2.3 showed no decrease in strength at all.

Claims (1)

[Scope of Claims] A fiber-reinforced composite material having inorganic fibers as a reinforcing material and an inorganic substance as a matrix, wherein the inorganic fibers are inorganic fibers obtained from a silicon-containing polycyclic aromatic polymer, and the constituent components thereof i) at least one type of crystal selected from the group consisting of a radial structure, an onion structure, a random structure, a core radial structure, a skin onion structure, and a mosaic structure derived from a polycyclic aromatic compound in a mesophase state constituting the polymer; ii) crystalline carbon and/or amorphous carbon in a non-oriented state derived from an optically isotropic polycyclic aromatic compound containing an organic solvent insoluble component constituting the polymer; , and iii) an amorphous phase consisting essentially of Si, C and O and/or crystalline ultrafine particles consisting essentially of β-SiC with a particle size of 500 Å or less and amorphous SiO_x (0<x≦ 2)
It is an aggregate consisting of Si, and the proportion of the constituent elements is Si; 30 ~
70% by weight, C: 20-60% by weight and O: 0.5-1
0% by weight of a Si-C-O material, the inorganic material is an inorganic material obtained from a metal-containing polycyclic aromatic polymer, and its constituent components are: a) Crystalline carbon derived from a polycyclic aromatic compound in a mesophase state constituting the polymer, or crystalline carbon and amorphous carbon, b) Optically isotropic polycyclic constituting the polymer non-oriented crystalline carbon and/or amorphous carbon derived from an aromatic compound; and c) an amorphous substance consisting essentially of (1) Si, M, C and O; and/or (2) ) Crystalline ultrafine particles with a particle size of 500 Å or less consisting essentially of β-SiC, MC, a solid solution of β-SiC and MC, and MC_1_-_x, and amorphous SiO_y and MO_z
The proportion of the constituent elements is Si: 5-70% by weight, M: 0.5-70% by weight.
45% by weight, C: 20-40% by weight and O: 0.01-
30% by weight of Si-M-C-O material (where M
is at least one element selected from Ti, Zr, and Hf, and satisfies 0<x<1, 0<y≦2, and 0<z≦2. ) A fiber-reinforced carbonaceous composite material characterized by being a carbonaceous inorganic material.