JPH0757715B2 - Fiber-reinforced carbonaceous composite material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat resistant and wear resistant carbonaceous inorganic composite material having excellent mechanical properties.

(Prior art and its problems) Among the carbonaceous inorganic composite materials reinforced with inorganic fibers, the so-called C / C composite, which uses carbon fiber as the reinforcing fiber and carbon as the inorganic matrix, has a specific strength, a specific elasticity, and a non-oxidizing property. It has excellent heat resistance, toughness, and friction characteristics in a strong atmosphere and is promising as a heat-resistant structural material and brake material. Particularly for brake applications, practical application is proceeding for aircraft and racing cars.

However, in the C / C composite, fatal cracks and peeling are likely to occur at the interface between the reinforcing material and the matrix carbon, and sufficient mechanical strength cannot be obtained. Also, in the C / C composite, the matrix is composed only of carbon. However, although it is difficult to use it for a long time in an oxidizing atmosphere, and the friction property is excellent in lubricity, the wear resistance is not always sufficient.

For the purpose of improving this defect and improving the interfacial adhesion between the carbon fiber and the matrix carbon, a method of sizing the surface of the carbon fiber with various treatment agents or a method of coating by a method such as CVD is performed. There is.

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

On the other hand, the method of applying coating treatment to each fiber is
It is necessary to add processes with low productivity such as CVD process,
Since the cost of the composite material is high and the fiber diameter of the obtained fiber is large, the suppleness is lost and the flexibility of the composite material design is greatly reduced.

On the other hand, when a commercially available amorphous inorganic fiber such as a silicon carbide fiber is used as the reinforcing fiber, the adhesiveness of the reinforcing fiber with the carbon matrix is improved, but the inorganic fiber is at a temperature at which the carbon matrix is sufficiently crystallized. However, since the mechanical strength cannot be sufficiently maintained, the mechanical properties of the composite material could not be improved.

On the other hand, as a method for improving the oxidation resistance and wear resistance of matrix carbon, in Walker (BEWalker.Jr) et al. In Am.Ceram.Soc.Bull.62 (1983) 916, C / C composite was treated with organosilicon. A method of impregnating a polymer and then thermally decomposing it to introduce a silicon carbide component into the matrix is described, but the bending strength of the obtained composite material is as low as 158 MP.

Also, Proc.of Int.Symp.on Ceramic, Compon.for Engin
e, 1983, Japan, p505, Fittour (E.Fitze
r) et al. describe a method of impregnating a C / C composite with a silicon melt to convert the matrix into silicon carbide, but the obtained composite material remains unreacted between the matrix particles. Because of the metallic silicon, which undergoes creep metamorphism at high temperatures above 1300 ° C, it does not have the high-temperature characteristics of C / C composites.

In any of the above processes, in addition to the conventional complicated C / C composite manufacturing process, a more complicated process was added, which made industrial use difficult.

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

Another object of the present invention is to provide an inorganic fiber reinforced carbonaceous material having excellent mechanical properties.

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

The inorganic fiber-reinforced carbonaceous composite material of the present invention is a composite material having an inorganic fiber as a reinforcing material and an inorganic substance as a matrix, wherein the inorganic fiber is an inorganic fiber obtained from a metal-containing polycyclic aromatic polymer. And its constituent components are: a) a 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 which constitutes the polymer. At least one selected carbonaceous material having a crystalline alignment state, b) a non-oriented crystalline carbon derived from an optically isotropic polycyclic aromatic compound containing an organic solvent insoluble component constituting the polymer, and And / or amorphous carbon, and c) an amorphous material consisting essentially of Si, M, C and O,
And / or substantially β-SiC, MC, a solid solution of β-SiC and MC and MC
_It is an aggregate of crystalline ultrafine particles of _{1-x with} a particle size of 500Å or less and amorphous SiO _y and MO _z. The proportion of constituent elements is Si; 5 to 70% by weight, M; 0.5 to 45% by weight. %,
C: 20-40% by weight and O: 0.01-30% by weight, Si-M-
C—O substance (wherein M is at least one element selected from Ti, Zr and Hf, and 0 <x <1, 0 <y ≦
2, 0 <z ≦ 2. ) A high-strength, high-modulus inorganic fiber, wherein the inorganic substance is an inorganic substance obtained from a silicon-containing polycyclic aromatic polymer, the constituent components of which are: i) a mesophase state that constitutes the polymer. Carbon derived from the polycyclic aromatic compound, or crystalline carbon and amorphous carbon, ii) a non-oriented state derived from the optically isotropic polycyclic aromatic compound constituting the polymer Crystalline carbon and / or amorphous carbon, and iii) an amorphous phase consisting essentially of Si, C and O and / or crystalline ultrafine particles consisting essentially of β-SiC having a particle size of 500Å or less. And amorphous SiO _x (0 <x ≦ 2), the proportion of constituent elements is Si; 30 to 70% by weight, C; 20 to 60% by weight, and O; 0.5 to 10% by weight. It is a carbonaceous inorganic substance consisting of a certain Si-C-O substance.

First, the inorganic fiber in the present invention will be described in detail.

In the following description, "part" means "part by weight" and "%"
Is "% by weight".

The inorganic fiber of the present invention comprises the above-mentioned constituents a), b) and c), and Si: 0.01-30%, M: 0.01-10%,
C; 65-99.9% and O; 0.001-10%, preferably Si; 0.1-2
Substantially composed of 5%, M; 0.01-8%, C; 74-99.8% and O; 0.01-8%.

The crystalline carbon, which is a constituent component of this inorganic fiber, has a crystallite size of 500 Å or less, and corresponds to a 3.2 Å (002) plane oriented in the fiber axis direction in a high resolution electron microscope having a resolution of 1.5 Å. It is an ultrafine graphite crystal that allows the observation of a fine lattice image. The crystalline carbon in the inorganic fiber may 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, or the like. This is due to the presence of the mesophase polycyclic aromatic compound in the raw material.

The sum of constituents a) and b) of this inorganic fiber is 100
The ratio of component c) to parts is 0.015 to 200 parts,
Moreover, the ratio of the constituents a) and b) is 1: 0.02-4.

When the ratio of the constituent component c) to the total 100 parts of the constituent components a) and b) is less than 0.015, it is almost the same as that of the pitch fiber, and the oxidation resistance and the wettability with respect to the matrix are not expected to be improved. If the amount exceeds the above range, fine graphite crystals are not effectively formed, and a fiber having a high elastic modulus cannot be obtained.

The inorganic fiber in the present invention is mainly composed of 1) (Si—CH ₂ ) bond unit, or (Si—CH ₂ ) bond unit and (Si—Si) bond unit, and has a hydrogen atom or a lower alkyl in the side chain of silicon. Group, a phenyl group or a silyl group, in the silicon atom of the main skeleton consisting of the above-mentioned bond unit,
M (M is at least one element selected from the group consisting of titanium, zirconium and hafnium),
At least a part of the silicon atoms of the transition metal-containing organosilicon polymer bonded to at least a part of the silicon atoms directly or through an oxygen atom is a polycyclic aroma of a petroleum-based or coal-based pitch or a heat-treated product thereof. Random copolymer in which carbon of aromatic ring of aromatic group compound is bonded through silicon-carbon linking group, and 2) both mesophase or mesophase and optically isotropic phase obtained from petroleum-based or coal-based pitch A polycyclic aromatic compound consisting of a phase (hereinafter, both may be collectively referred to as “mesophase polycyclic aromatic compound”) at a temperature in the range of 200 to 500 ° C. and / or by heating and melting. A first step of obtaining a polycyclic aromatic polymer containing M and silicon, a second step of preparing a spinning stock solution of the metal-containing polycyclic aromatic polymer, and spinning the same; Or nothing Third infusible under tension
And a fourth step of firing the infusibilized spun fiber at a temperature in the range of 800 to 3000 ° C. in a vacuum or an inert gas atmosphere.

Each of the above steps will be described more specifically.

First step: The precursor polymer (1) is prepared by heating and reacting the organosilicon polymer and pitch in an inert gas, preferably at a temperature in the range of 250 to 500 ° C.

The organosilicon polymer, which is one of the starting materials for the precursor polymer (1), is obtained by heating polymethylsilane obtained by the reaction of dimethyldichlorosilane and metallic sodium to 400 ° C. or more in an inert gas. can get. The organosilicon polymer has a (Si—CH ₂ ) bond unit or (Si—C).
H ₂ ) bond units and (Si-Si) bond units, and the ratio of the total number of (Si-CH ₂ ) bond units to the total number of (Si-Si) bond units is in the range of 1: 0 to 20. is there.

The weight average molecular weight (M _w ) of the organosilicon polymer is generally 300 to 1000, and the M _w of 400 to 800 is a random copolymer which is an intermediate raw material for obtaining an excellent carbon-based inorganic fiber. Particularly preferred for preparing polymer (2).

Pitch, which is another starting material of the precursor polymer (1), is a pitch obtained from petroleum or coal, and a particularly preferable pitch is a heavy oil obtained by fluid catalytic cracking of petroleum, or a heavy oil thereof. Distillate or residual oil obtained by distilling
Furthermore, these are heat-treated products.

The pitch contains 5 to 98% of insoluble components in organic solvents such as benzene, toluene, xylene, and tetrahydrofuran.
The content of the insoluble component is preferably 40 to 90% by weight, and when the pitch of the insoluble component is less than 5% by weight is used as a raw material, an inorganic fiber having excellent strength and elastic modulus cannot be obtained, and the insoluble component is not obtained. When more than 98% by weight of pitch is used as a raw material, the copolymer has a high melting point, which makes spinning difficult.

The weight average molecular weight (M _w ) of this pitch is 100 to 3000. The weight average molecular weight is a value determined as follows. That is, when the pitch does not contain the organic solvent insoluble matter for gel permeation chromatograph (GPC) measurement such as benzene, toluene, xylene, tetrahydrofuran, chloroform and dichlorobenzene, the GPC measurement is performed as it is, and the pitch is the above organic solvent insoluble matter. If it contains
Hydrogenation treatment is carried out under mild conditions, the organic solvent-insoluble matter is changed to the organic solvent-soluble component, and post-GPC measurement is carried out. 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.

The ratio of the pitch used is 83 to 4 per 100 parts of the organosilicon polymer.
It is preferably 900 parts. If the proportion of the pitch used is too small, the amount of silicon carbide component in the resulting inorganic fiber will be large, and it will not be possible to obtain an inorganic fiber having a high elastic modulus. If the proportion is too large, the silicon carbide component will be large. Is less, and it becomes impossible to obtain an inorganic fiber having excellent wettability to the matrix and oxidation resistance.

When the reaction temperature of the above reaction is excessively low, the bond between the silicon atom and the aromatic carbon is hard to be generated, and when the reaction temperature is excessively high, decomposition and high molecular weight of the generated precursor polymer (1) occur violently. Not preferable. The polymer (1) referred to herein includes, in addition to the copolymer in which the organosilicon polymer and the pitch are bonded via the silicon-carbon linking group, the polycondensate of the organosilicon polymer and the pitch. .

Nitrogen, argon and the like are preferably used as the inert gas.

Next, the precursor polymer (1) and the transition metal compound represented by the formula MX ₄ are reacted at a temperature in the range of 100 to 500 ° C. to produce a random copolymer (2).

In the above-mentioned MX ₄ , M is at least one element selected from Ti, Zr and Hf, and X is capable of binding M to silicon of the precursor polymer (1) directly or through an oxygen atom by condensation. However, a halogen atom, an alkoxy group, or a complex-forming group such as β-diketone is preferable.

If the reaction temperature is excessively low, the condensation reaction between the precursor polymer (1) and the formula MX ₄ will not proceed, and if the reaction temperature is excessively high, the crosslinking reaction of the precursor polymer (1) via M will be excessive. And gelation occurs, the precursor polymer (1) itself condenses to a high molecular weight, or in some cases MX ₄ is volatilized to produce an excellent inorganic fiber. You can't get united (2).

As an example, when M is Ti and X is OC ₄ H ₉ , the reaction temperature is 2
00 to 400 ° C is suitable.

By this reaction, a random copolymer (2) in which at least a part of silicon atoms of the precursor polymer (1) is bonded to the metal M directly or via an oxygen atom is prepared.

The metal M can be bonded to the silicon atom of the precursor polymer (1) in a side chain form by a bonding mode such as -MX ₃ or -O-MX ₃ , or directly to the silicon atom of the polymer (1). Alternatively, a bonding mode of crosslinking via oxygen may be adopted.

As the method for preparing the random copolymer (2), in addition to the method described above, a method of reacting an organosilicon polymer with MX ₄ and further reacting the obtained product with pitch can be used. .

In the first step, finally, the random copolymer (2) and the mesophase polycyclic aromatic compound are heated and / or heated and melted to prepare a metal-containing polycyclic aromatic polymer.

Mesophase polycyclic aromatic compound, for example, heating petroleum-based or coal-based pitch in an inert gas to 300 ~ 500 ℃,
It can be prepared by polycondensation while removing the produced soft fraction.

If the condensation polymerization reaction temperature is excessively low, the condensed ring does not grow sufficiently, and if the temperature is excessively high, an insoluble or infusible product is produced by coking.

The above mesophase polycyclic aromatic compound has a melting point of 200
~ 400 ℃, the weight average molecular weight of 200 ~ 10
It is 000.

Among the mesophase polycyclic aromatic compounds, 20-100
%, Especially 40-100% optical anisotropy, 30-100%
Of those containing an insoluble matter in benzene, toluene, xylene, or tetrahydrofuran is preferable in order to obtain an inorganic fiber having excellent mechanical performance.

The proportion of the mesophase polycyclic aromatic compound used is 5 to 50,000 parts per 100 parts of the random copolymer (2), more preferably 5 to 10,000 parts. If it is less than 5 parts, the mesophase content in the product is insufficient. If a highly elastic fired yarn cannot be obtained, and if it is more than 50,000 parts, an inorganic fiber excellent in wettability to a matrix and oxidation resistance cannot be obtained due to lack of a silicon component.

At least a portion of the random copolymer (2) is mesophase polycyclic by heating and melting and / or reacting the random copolymer (2) and the mesophase polycyclic aromatic compound in a temperature range of 200 to 500 ° C. A metal-containing polycyclic aromatic polymer bonded with an aromatic compound is obtained. However,
The term "bond" as used herein means a chemical bond between silicon of the random copolymer (2) and carbon of the polycyclic aromatic compound and a polycyclic aromatic ring portion chemically bonded to silicon of the random copolymer (2). It means a physical bond such as van der Waals bond with the mesophase polycyclic aromatic compound.

When the melt-mixing temperature is lower than 200 ° C, an infusible portion is generated,
The yarn becomes non-uniform, which adversely affects the strength and elastic modulus of the inorganic fiber, and when the melt-mixing temperature is higher than 500 ° C, the condensation reaction proceeds violently, the resulting polymer has a high melting point, and the spinning of the polymer is remarkable. It will be difficult.

The method for preparing the metal-containing polycyclic aromatic polymer,
In addition to the method described above, a method of reacting an organosilicon polymer with pitch, adding a mesophase polycyclic aromatic compound and MX ₄ simultaneously or sequentially to the obtained product, and further reacting, is also possible.

The weight average molecular weight of the metal-containing polycyclic aromatic polymer is 20
It has a melting point of 200 to 400 ° C. at 0 to 11000.

Second step: The spinning polymer, which is the metal-containing polycyclic aromatic polymer obtained in the first step, is heated and melted, and in some cases, this is filtered to remove substances such as microgels and impurities that are harmful during spinning. This is spun by a commonly used synthetic fiber spinning device.

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

In the spinning device, a spinning tube is attached if necessary,
After making the atmosphere in the spinning cylinder one or more atmospheres selected from the group consisting of air, inert gas, hot air, heat inert gas, steam, and ammonia gas, a small diameter is obtained by increasing the winding speed. Fibers can be obtained. The spinning speed in the melt spinning varies depending on the average molecular weight of the raw material, the molecular weight distribution, and the molecular structure, but is 50 to 5000.
It is preferably in the range of m / min.

Third step: The spun fiber obtained in the second step is infusibilized under the action of tension or no tension.

A typical infusibilizing method is a method of heating spun fibers in an oxidizing atmosphere. The temperature of infusibilization is preferably 50 to 400
The temperature is in the range of ° C. When the infusibilization temperature is excessively low, the polymer constituting the spinning yarn does not hang up, and
If this temperature is too high, the polymer will burn.

The purpose of infusibilization is to make the polymer that constitutes the spun fiber into an infusible or insoluble state of a three-dimensional structure so that it will not melt during the firing of the next step and will not fuse with adjacent fibers. Is. Examples of the gas forming the oxidizing atmosphere at the time of infusibilization include air, ozone, oxygen, chlorine gas, bromine gas, ammonia gas, and mixed gas thereof.

As another infusibilizing method different from the above, the spun fiber is infusibilized by γ-ray irradiation or electron beam irradiation while heating at low temperature in an oxidizing atmosphere or a non-oxidizing atmosphere under tension or no tension as necessary. Methods can also be employed.

The purpose of irradiating this γ ray or electron beam, by further polymerizing the polymer forming the spun fiber,
This is to prevent the spinning raw yarn from melting and losing the fiber shape.

The appropriate irradiation dose of gamma rays or electron beams is 10 ⁶ to 10 ¹⁰ rads.

Irradiation can be performed in a vacuum, an inert gas atmosphere, or an oxidizing gas atmosphere such as air, ozone, oxygen, chlorine gas, bromine gas, ammonia gas, or a mixed gas thereof.

The infusibilization by irradiation can be performed at room temperature, and if necessary, the infusibilization can be achieved by heating while heating in the temperature range of 50 to 200 ° C.

If the infusibilization is carried out under no tension, the spun fiber will have a wavy shape due to shrinkage, but in some cases it can be corrected in the firing step of the next step, tension is not always necessary, but tension acts In such a case, a good result can be obtained by applying a tension higher than the tension that can at least prevent the spun fiber from contracting and becoming wavy during infusibilization.

When infusibilizing, the tension applied is 1 to 500 g / mm ²
The range is preferable, and even if a tension of 1 g / mm ² or less is applied, it is not possible to give tension that does not cause the fiber to sag, and
The fiber may break when a tension of 0 g / mm ² or more is applied.

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 an inert gas atmosphere, inorganic fibers mainly composed of carbon, M, silicon and oxygen are produced. can get.

In the firing step, it is not always necessary to apply tension, but high-temperature inorganic fiber with less bending can be obtained by firing at high temperature while applying tension in the range of 0.001 to 100 Kg / mm ² .

In the heating process, mineralization becomes severe from about 700 ℃,
It is estimated that mineralization is almost completed at about 800 ° C. Therefore, the firing is preferably performed at a temperature of 800 ° C. or higher. Moreover, since an expensive device is required to obtain a temperature higher than 3000 ° C., firing at a temperature higher than 3000 ° C. is not practical in terms of cost.

In addition, Si-M- which is the constituent component c) of the inorganic fiber of the present invention.
The form of the C—O material is determined by the manufacturing conditions used in the first to fourth steps. Generally speaking, number four
If the firing temperature in the process is lower than 1000 ℃, for example, Si,
It is substantially composed of an amorphous material composed of M, C, and O.

On the other hand, when the firing temperature in the fourth step is, for example, 1700 ° C. or higher, substantially β-SiC, MC, a solid solution of β-SiC and MC and MC
_1-x (provided that 0 <x <1) ultrafine particles with a particle size of 500Å or less and amorphous composed of SiO _y (provided that 0 <y ≦ 2) and MO _z (provided that 0 <z ≦ 2) Substantially composed of an aggregate consisting of.

In the middle of the above temperature, it is composed of a mixed system of each aggregate. Further, the amount of oxygen in the inorganic fiber can be controlled by, for example, the addition ratio of MX ₄ in the first step or the infusibilizing condition in the third step.

Further, the distribution state of the constituent component c) can be controlled by the atmosphere during firing and the size and concentration of the mesophase in the raw material. For example, when the mesophase is grown large, the constituent component c) tends to be extruded into the fiber surface phase.

Next, a method for producing a silicon-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 described.

The silicon-containing polycyclic aromatic polymer is 1) binding unit (Si-CH _2), or mainly consists of coupling units (Si-CH ₂₎ and the coupling unit (Si-Si), hydrogen atoms in the side chain of silicon atoms , A lower alkyl group, a phenyl group and a silyl group, having a side chain group selected from the group consisting of bond units (Si-
The ratio of the total number of CH ₂ ) to the total number of bonding units (Si-Si) is 1: 0 to 20
At least a part of the silicon atoms of the organosilicon polymer in the range of 1 to 100 is bonded to the carbon of the aromatic ring of the petroleum-based or coal-based pitch or the heat-treated product thereof (1) 100 parts and 2) petroleum-based Alternatively, it is produced by heat-reacting and / or heat-melting 5 to 50,000 parts of a mesophase polycyclic aromatic compound obtained by heat-treating coal-based pitch at a temperature in the range of 200 to 500 ° C.

For the precursor polymer (1), the first step of producing the inorganic fiber can be applied as it is.

Since the silicon-containing polycyclic aromatic polymer is not required to be made into fibers, it may be set in a somewhat wider range than in the case of the first step of producing the inorganic fibers. That is, the proportion of the pitch used in the production of the precursor polymer (1) is preferably 10 to 4900 parts per 100 parts of the organosilicon polymer.

The silicon-containing polycyclic aromatic polymer is prepared by heating and / or melting the precursor polymer (1) and the mesophase polycyclic aromatic compound produced in the first step of producing the inorganic fiber by heating.

The use ratio of the mesophase polycyclic aromatic compound is preferably 5 to 50,000 parts per 100 parts of the random copolymer (2), and if it is less than 5 parts, the mesophase content in the product will be insufficient, so that the obtained heavy A highly elastic composite material cannot be obtained even if the coalesce is mineralized, and if it is more than 50,000 parts, the matrix obtained by the mineralization of the polymer due to the lack of a silicon component is inferior in wettability to the reinforcing fiber,
Oxidation resistance is not sufficient.

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

First, a method of adding the silicon-containing polycyclic aromatic polymer powder to various woven fabrics such as the plain weave, satin weave, imitation weave, twill weave, spiral woven fabric, and three-dimensional woven fabric of the above-mentioned inorganic fibers, and forming the woven fabric. After impregnation with a solution or slurry of a silicon-containing polycyclic aromatic polymer, the solvent is removed, a method of heat-molding a dried prepreg sheet, the inorganic fiber short fiber, or chopped fiber and a silicon-containing polycyclic aromatic polymer. A fiber-containing molded body is manufactured by melt-kneading, press molding, injection molding, or the like. At that time, the content of the inorganic fibers in the molded body is preferably 10 to 70% by volume.

Further, in the production of the fiber-containing molded body, the silicon-containing polycyclic aromatic polymer, for example, in an inert gas atmosphere, the polymer is fired at 800 ~ 1000 ℃, mixed with a calcined body powder that is mineralized. , Can be used.

This calcined powder is Si: 0.01-69.9%, C: 29.9-99.9%
And O: 0.001-10%.

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

As the method of infusibilizing treatment, the method of the third step of producing the inorganic fiber can be adopted as it is.

The infusibilized molded body can be vacuumed or in an inert gas.
Firing at a temperature in the range of 800 to 3000 ° C. gives a mineralized, fiber-reinforced composite material with a matrix of carbon, silicon and oxygen.

In the heating process, mineralization becomes severe from about 700 ℃,
It is estimated that mineralization is almost completed at about 800 ° C. Therefore, the firing is preferably performed at a temperature of 800 ° C. or higher. Moreover, since an expensive apparatus is required to obtain a temperature higher than 3000 ° C., firing at a temperature higher than 3000 ° C. is impractical in terms of cost.

The infusibilizing step can be omitted by extremely slowing the temperature rise rate of the mineralization in this step, using a shape-retaining jig such as a molded body shape-retaining jig, or a powder head. It is also possible to obtain a high density composite material in one step by using a high temperature hot press as a molding method.

Since the fiber-reinforced carbonaceous composite material obtained by firing and mineralization contains open pores to some extent, if necessary, after impregnation with the melt, solution or slurry of the silicon-containing polycyclic aromatic polymer, By making the composite infusible, firing and making it inorganic, it is possible to increase the density and strength of the composite.
The impregnation may be performed by using a melt, a solution or a slurry of a silicon-containing polycyclic aromatic polymer, but in order to permeate fine open pores, a solution or slurry of the polymer is added to this composite material. After impregnation with the above, the temperature is increased while accelerating the permeation into the fine pores under reduced pressure, the solvent is distilled off, the temperature is raised, and the pressure is applied to 10 to 500 kg / cm ² to fill the pores with the melt of the polymer.

The obtained impregnated body is infusibilized in the same manner as in the third step,
It can be calcined and made inorganic. By repeating this operation 2 to 10 times, a high density and high strength fiber reinforced composite material can be obtained.

(Effects of the Invention) The fiber-reinforced carbonaceous composite material of the present invention has high strength, high elasticity, and improved adhesiveness with the carbon matrix, and therefore 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 fiber and the matrix, a material having excellent oxidation resistance and abrasion resistance can be obtained.

Therefore, the obtained composite material is excellent in mechanical properties, oxidation resistance and abrasion resistance, and is excellent as various brakes and heat resistant structural materials.

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

Reference Example 1 (Production of Inorganic Fiber I) Into a three-necked flask of No. 5, 2.5 g of anhydrous xylene and 400 g of sodium were placed, heated to the boiling point of xylene under a nitrogen gas stream, and dimethyldichlorosilane 1 was added dropwise for 1 hour. After completion of the dropping, the mixture was heated under reflux for 10 hours to form a precipitate. The precipitate was filtered, washed with methanol and then with water to obtain 420 g of white powdery polydimethylsilane.

400 g of this polydimethylsilane, a gas introduction tube, a stirrer,
A three-necked flask equipped with a condenser and a distilling tube was charged into a three-necked flask, and heat-treated at 420 ° C under a nitrogen stream of 50 ml / min with stirring, and 350 g of a colorless transparent slightly viscous liquid was put in a distilling receiver. Got

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

The infrared absorption spectrum of this substance was measured and found to be 65
Absorption of Si-CH ₃ at 0-900 cm ^-1 and 1250 cm ^-1 , Si at 2100 cm ^-1
Absorption of -H, Si-CH ₂ -Si absorption of the of 1020 cm ^-1 and near 1355 cm ^-1, absorption of CH was observed at 2900 cm ^-1 and 2950 cm ^-1,
Further, when the far-infrared absorption spectrum of this substance was measured, absorption of Si-Si was observed at 380 cm ^-1 , and thus the obtained liquid substance was mainly composed of (Si-CH ₂ ) bond units and (Si-Si). It was found to be an organosilicon polymer having a bonding unit and having a hydrogen atom and a methyl group in the side chain of silicon.

From the results of nuclear magnetic resonance analysis and infrared absorption analysis, this organosilicon polymer shows that the total number of (Si—CH ₂ ) bond units is
It was confirmed that the polymer had a ratio of the total number of -Si) bond units of approximately 1: 3.

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

Measurement of the infrared absorption spectrum of this material, the absorption peak similar to that described above was observed, the material consists predominantly (Si-CH ₂₎ coupling units and (Si-Si) bond unit, hydrogen on the side chain of the silicon It was found to be an organosilicon polymer having atoms and methyl groups.

From the results of nuclear magnetic resonance analysis and infrared absorption analysis, this organosilicon polymer shows that the total number of (Si—CH ₂ ) bond units is
It was confirmed that the polymer had a ratio of the total number of -Si) bond units of about 7: 1.

On the other hand, among petroleum fractions, high boiling point substances above light oil are
Fluid catalytic cracking / rectification was carried out at a temperature of 500 ° C. in the presence of an alumina cracking catalyst to obtain a residue from the bottom of the column. Hereinafter, this residue is referred to as FCC slurry oil.

As a result of elemental analysis, the FCC slurry oil had an atomic ratio of carbon atoms to hydrogen atoms (C / H) of 0.75 and an aromatic carbon ratio of 0.55 by nuclear magnetic resonance analysis.

700 g of the above FCC slurry oil was heated to 450 ° C. under a nitrogen gas stream, and after distilling 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 A minute removal pitch of 200 g was obtained.

The light content removal pitch was an optically isotropic pitch containing 25% of xylene-insoluble matter.

180 g of this light content removal pitch was subjected to polycondensation at 400 ° C. for 8 hours under a nitrogen stream while removing the light content produced by the reaction to obtain a heat treatment pitch 97.2.

This heat-treated pitch contains a melting point of 263 ° C, a softening point of 308 ° C, xylene insoluble content of 77%, and quinoline insoluble content of 31%. It was a family compound.

Organosilicon polymer 2 obtained in Reference Example 1 with 57 g of light component removal pitch
5 g and 20 ml of xylene were added, the temperature was raised with stirring, the xylene was distilled off, and the mixture was reacted at 400 ° C. for 4 hours to obtain 57.4 g of a precursor polymer (1).

As a result of infrared absorption spectrum measurement, this precursor polymer (1) was found to have Si-H bonds (IR: 2100c) present in the organosilicon polymer.
m ^-1 ) decrease and new Si-C (carbon of benzene ring)
The formation of a bond (IR: 1135 cm ^-1 ) was found to indicate that the organosilicon polymer is a polymer having a part of silicon atoms directly bonded to carbon of a polycyclic aromatic ring.

To 57.4 g of the precursor polymer (1), tetraoctoxytitanium [Ti
(OC ₈ H ₁₇ ) ₄ ] 3.87 g of xylene solution (25% xylene solution 15.5 g) was added, and xylene was distilled off, followed by reaction at 340 ° C. for 1 hour to obtain 56 g of a random copolymer (2).

This polymer did not contain a xylene-insoluble portion, had a weight average molecular weight of 1580, a melting point of 258 ° C. and a softening point of 292 ° C., and was xylene-soluble.

6.4 g of the random copolymer (2) and 90 g of the mesophase polycyclic aromatic compound were mixed and melt-heated at 380 ° C. for 1 hour in a nitrogen atmosphere to obtain a metal-containing polycyclic aromatic polymer in a uniform state.

The melting point of this polymer was 264 ° C., the softening point was 307 ° C., and it contained 68% xylene-insoluble matter.

Using the above-mentioned high molecular weight material as a raw material for spinning, using a metal nozzle having a nozzle diameter of 0.15 mm, melt spinning is performed at 360 ° C., the obtained spun raw yarn is oxidized in air at 300 ° C., infusible, Firing was performed at 1300 ° C. in an argon atmosphere to obtain an inorganic fiber having a diameter of 7.5 μm.

This fiber has a tensile strength of 358 kg / mm ² and a tensile elastic modulus of 32 t / mm ² , and the fracture surface was observed using a scanning electron microscope, which revealed a coral-like random radial mixed structure with multiple layers of crystals. there were.

After crushing this inorganic fiber, alkali melting and hydrochloric acid treatment are applied to obtain an aqueous solution, and then high frequency plasma emission spectroscopy (IC
As a result of performing P), the silicon content was 0.95% and the titanium content was 0.06%.

Reference Example 2 (Production of Inorganic Fiber II) 1.8 g of a random copolymer (2) obtained in the same manner as in Example 1
And 90 g of mesophase polycyclic aromatic compound under nitrogen flow, 4
The mixture was melt-mixed at 00 ° C. for 1.5 hours to obtain a spinning polymer having a melting point of 265 ° C. and a xylene-insoluble content of 55%.

This polymer using a metal nozzle with a nozzle diameter of 0.15 mm,
Melt-spin at 350 ℃, the resulting spun yarn is oxidized in the air at 300 ℃, infusibilized, and further in an argon atmosphere, 2
Firing was performed at 500 ° C. to obtain an inorganic fiber II having a diameter of 7 μm.

As a result of ICP analysis of this inorganic fiber II in the same manner as in Example 1,
The silicon content was 0.3% and the titanium content was 0.015. Also,
The tensile strength of this fiber was 345 kg / mm ² , and the tensile elastic modulus was 60 t / mm ² .

Reference Example 3 (Production of Inorganic Fiber III) 39 g of the precursor polymer (1) obtained in Reference Example 1 was added with an ethanol-xylene solution (1.5%) of 5.4 g of tetrakisacetylacetonatozirconium, and after distilling off xylene, 250 ° C. In 1
Polymerization was carried out for a period of time to obtain 39.5 g of a random copolymer (2).

20 g of this polymer and 50 g of mesophase polycyclic aromatic compound prepared in the same manner as in Reference Example 1 were finely pulverized and mixed, melt-mixed at 360 ° C. for 1 hour, and spun at 350 ° C. using a nozzle having a nozzle diameter of 0.2 mm. The obtained spun raw yarn in air 250
The mixture was infusibilized at ℃, and further baked at 1400 ℃ in an argon atmosphere to obtain an inorganic fiber having a diameter of 11μ.

The tensile strength of this fiber was 345 kg / mm ² , and the tensile elastic modulus was 35 t / mm ² .

Reference Example 4 (Production of Inorganic Fiber IV) The same procedure as in Reference Example 1 was repeated except that the light content removal pitch and the usage amount of the organosilicon polymer were changed to 60 g and 40 g, respectively.
g of precursor polymer (1) was obtained.

An ethanol-xylene solution (1.5%) of 72 g of hafnium chloride was added to 40 g of the precursor polymer (1), and xylene was distilled off, followed by polymerization at 250 ° C. for 1 hour to obtain 43.5 g of a random copolymer (2).

20 g of this polymer and 80 g of mesophase polycyclic aromatic compound were finely pulverized and mixed, and then melt-mixed at 360 ° C. for 1 hour.
Melt-spin at 50 ° C, infusibilize at 270 ° C, and 120 in argon.
By firing at 0 ° C., 12.5μ of inorganic fiber was obtained.
The tensile strength of this fiber was 335 kg / mm ² , and the tensile elastic modulus was 35 t / mm ² .

Reference Example 5 (Production of Silicon Carbide Fiber) The silicon carbide fiber obtained from only polycarbosilane used in Comparative Example 2 was produced as follows.

3 parts by weight of polyborosiloxane was added to 100 parts by weight of polydimethylsilane synthesized by dechlorinating and condensing dimethylchlorosilane with sodium metal, and heat-condensed at 350 ° C. in nitrogen to obtain a compound represented by the formula (Si—CH ₂ ). A polycarbosilane having a main chain skeleton mainly composed of the carbosilane unit and having a hydrogen atom and a methyl group in the silicon atom of the carbosilane unit was obtained. This polymer is melt-spun and heated in air at 190 ° C.
Infusibilized, then fired in nitrogen at 1300 ° C to obtain a silicon carbide fiber consisting mainly of silicon, carbon and oxygen with a fiber diameter of 13μ, a tensile strength of 300 Kg / mm ² and a tensile elastic modulus of 16 t / mm ^2. Got

Reference Example 6 (Production of Polymer I) 6.4 g of the precursor polymer (1) in Reference Example 1 and 90 g of mesophase polycyclic aromatic compound were mixed, and the mixture was mixed at 1 at 380 ° C. under a nitrogen atmosphere.
Polymer I was produced by melt mixing for a period of time.

Reference Example 7 (Production of Polymer II) A precursor polymer (1) was obtained in the same manner as in Reference Example 1 from 50 g of the organosilicon polymer and 50 g of the light component removal pitch in Reference Example 1.

The precursor polymer (1) and the mesophase polycyclic aromatic compound in Reference Example 1 were mixed at a ratio of 1: 1 and the mixture was mixed under a nitrogen atmosphere.
Polymer II was produced by melt mixing at 80 ° C. for 1 hour.

Example 1 A two-dimensional plain weave woven fabric of inorganic fibers I obtained in Reference Example 1 was prepared to have a diameter of 7 cm.
Was cut into a disk shape, impregnated with a 30% xylene slurry of Polymer I and dried to prepare a prepreg sheet. In the mold, fine powder of polymer II was filled between the prepreg sheets, and each prepreg sheet was laminated 30 sheets while sequentially shifting the fiber direction of the reinforcing fibers by 45 °, and applying a pressure of 50 kg / cm ² .
Hot pressing was performed at 350 ° C to obtain a disk-shaped molded body. This molded body was embedded in a powder bed of carbon powder and held in shape, heated up to 800 ° C at a rate of 5 ° C / h in a nitrogen stream, and then 1300
The temperature was raised to ℃ and the matrix was made inorganic. The bulk density of the obtained composite material was 1.21 g / cm ³ .

This composite material was immersed in a 50% xylene slurry of polymer II, heated to 350 ° C while distilling off xylene under reduced pressure, and then pressure-impregnated to 100 kg / cm ² , and then in air at a rate of 5 ° C / h. The temperature was raised to 300 ° C., infusibilized, and then mineralized at 1300 ° C. This impregnation / mineralization treatment was further repeated 3 times to obtain a material having a bulk density of 1.93 g / cm ³ . The bending strength of the obtained composite material was 57 kg / mm ² .

Example 2 A mixture of 50 parts of an inorganic substance obtained by calcination of Polymer I in nitrogen at 1300 ° C. and 50 parts of a powder of Polymer I and a two-dimensional plain weave fabric of inorganic fiber II obtained in Reference Example 2 were alternately used. Paving, 400
Hot pressing was performed at 100 ° C. and 100 kg / cm ² to obtain a molded body. This molded body was mineralized in the same manner as in Example 1 and, using Polymer II, impregnation and mineralization were repeated in the same manner as in Example 1 four times. The obtained composite material has a bulk density of 2.00 g / cm ³ and a bending strength of 59 kg / mm ² .
Upon firing at 2200 ° C., the bulk density was improved to 2.03 g / cm ³ and the bending strength was improved to 63 kg / mm ² .

Comparative Example 1 As the reinforcing fiber, a commercially available PAN-based carbon fiber having a fiber type of 7 μm, a tensile strength of 300 kg / mm ² and a tensile elastic modulus of 21 t / mm ² was used instead of the inorganic fiber I of Reference Example 1, and the polymers I and II were used instead. A carbon fiber reinforced carbon material was obtained in the same manner as in Example 1, except that a petroleum-based heat-treated pitch having a softening point of 150 ° C. and a residual coal rate of 60% was used. This material had a low bulk density of 1.67 g / cm ³ and a bending strength of 15 kg / mm ² .

Comparative Example 2 Using the silicon carbide fiber obtained in Reference Example 5, an equal weight mixture of artificial graphite having a bulk density of 0.15 g / cm ³ under no load and powder of the same pitch as used in Comparative Example 1 was used as a matrix raw material. In the same manner as in Example 2, after forming a molded body by the hot pressing method, mineralizing, and further impregnating with the above pitch and mineralizing treatment were repeated 4 times, the bulk density was 1.90 g / cm 3.
^{At 3} , a composite material having a bending strength of 21 kg / mm ² was obtained. When an attempt was made to graphitize this composite material at 2200 ° C, the reinforcing fiber deteriorated and the strength decreased to 5 kg / mm ² .

Example 3 A composite material having a bulk density of 1.20 g / cm ³ was obtained in the same manner as in Example 1 except that the reinforcing fibers were inorganic fibers III.

Further, impregnation was conducted in the same manner as in Example 1 using Polymer II to obtain a composite material having a bulk density of 1.96 g / cm ³ and a bending strength of 59 kg / mm ² .

Example 4 A composite material having a bulk density of 1.24 g / cm ³ was obtained in the same manner as in Example 1 except that the reinforcing fiber was the inorganic fiber IV.

Further, the polymer II was impregnated in the same manner as in Example 1 to obtain a composite material having a bulk density of 2.03 g / cm ³ and a bending strength of 54 kg / mm ² .

Example 5 The composite materials of Examples 1, 2, 3, 4 and Comparative Examples 1 and 2 were mixed with 600
The bending strength was measured after a heat treatment for 1 hour in an oven in an air atmosphere at 0 ° C.

In the composite materials of Comparative Examples 1 and 2, oxidative deterioration had progressed to such an extent that strength could not be measured, but in the composite materials of Examples 1, 2, 3, and 4, no decrease in strength was observed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaki Shibuya 5 1978, Kozugushi, Ube City, Yamaguchi Prefecture 5 Ube Kosan Co., Ltd.

Claims (1)

[Claims] 1. A fiber-reinforced composite material comprising an inorganic fiber as a reinforcing material and an inorganic substance as a matrix, wherein the inorganic fiber is an inorganic fiber obtained from a metal-containing polycyclic aromatic polymer, and its constituent components are a) At least one crystal arrangement 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 which constitutes the polymer. A carbonaceous state, b) a non-oriented crystalline carbon and / or an amorphous carbon derived from an optically isotropic polycyclic aromatic compound containing an organic solvent insoluble component constituting the polymer, And c) an amorphous material consisting essentially of Si, M, C and O,
And / or substantially β-SiC, MC, a solid solution of β-SiC and MC and MC
_It is an aggregate of crystalline ultrafine particles of _{1-x with} a particle size of 500Å or less and amorphous SiO _y and MO _z. The proportion of constituent elements is Si; 5 to 70% by weight, M; 0.5 to 45% by weight. %,
C: 20-40% by weight and O: 0.01-30% by weight, Si-M-
C—O substance (wherein M is at least one element selected from Ti, Zr and Hf, and 0 <x <1, 0 <y ≦
2, 0 <z ≦ 2. ) A high-strength, high-modulus inorganic fiber, wherein the inorganic substance is an inorganic substance obtained from a silicon-containing polycyclic aromatic polymer, the constituent components of which are: i) a mesophase state that constitutes the polymer. Crystalline carbon derived from the polycyclic aromatic compound in, or crystalline carbon and amorphous carbon, ii) a non-oriented state derived from the optically isotropic polycyclic aromatic compound constituting the polymer Crystalline carbon and / or amorphous carbon, and iii) an amorphous phase consisting essentially of Si, C and O and / or crystalline ultrafine particles consisting essentially of β-SiC having a particle size of 500Å or less. And amorphous SiO _x (0 <x ≦ 2), the proportion of the constituent elements is Si; 30 to 70% by weight, C; 20 to 60% by weight, and O; 0.5 to 10% by weight. A fiber-reinforced carbonaceous composite material, which is a carbonaceous inorganic substance made of a certain Si-C-O substance.