JP4374339B2 - Brake member manufacturing method - Google Patents

Description

The present invention relates to the manufacture of a brake member used as a friction material for a brake disk mounted in conjunction with a speed control device used for stopping or speed control of a large land transport machine, for example, a large automobile. Regarding the method .

  As a friction material used in a braking device installed in a large land transportation machine such as a large automobile, a composite carbon fiber (hereinafter referred to as C / C) has a very high friction coefficient at a high temperature and is lightweight. Is also widely used.

  In such a large-scale ground transportation machine, braking by the brake must be continued for a long time according to the change of the driving situation, or it may be necessary to repeat the braking by the brake frequently, as a result. In the case of a braking device using C / C as a friction material, the friction material is exposed to a high temperature in air for a long time. Therefore, the friction material is basically composed of carbon fibers that are easily combusted at high temperatures. Under such conditions, the friction material not only reacts with oxygen and wears significantly, but also emits smoke. It has been reported that there are cases in which it has occurred and is about to reach a major accident. However, from the viewpoint of performance such as high frictional force at high temperatures and flexibility required for mounting on a disc brake, no alternative raw material has been found.

Excellent impact resistance possessed by C / C composite, while retaining excellent point light such, as a large land transportation machinery brake friction material hot is forced to occur, the wear in the presence of oxygen An object of the present invention is to provide a method for manufacturing a friction material for a brake that does not require replacement work with a significant frequency.

As a result of various investigations to achieve the above object, the inventors of the present invention formed a film made of a thermoplastic resin around a carbon fiber bundle containing a powdery binder pitch, cokes and a phenol resin, and made the softness. The intermediate material is obtained, and the flexible intermediate material is made into a yarn shape and laminated in a predetermined amount, and then molded by hot pressing at 300 to 2000 ° C. under the conditions of Jojo to 500 kg / cm ² to obtain a molded body, Alternatively, the molded body is fired to obtain a sintered body, and the molded body or the sintered body and Si are flowed through an inert gas of 0.1 NL or more per 1 kg of the total weight, and 1100 to 1400 ° C., and the furnace pressure is 0. after holding for 1 hour or more at .1～10HPa, by heating to from 1450 to 2,500 ° C. in furnace pressure 0.1～10HPa, containing a bundle and a carbon component other than carbon fibers of at least carbon fiber yarn A yarn assembly that is three-dimensionally combined and integrated so as not to separate from each other, and a matrix made of Si-SiC-based material that is filled between adjacent yarns in the yarn assembly. provided able production of fiber composite materials are, the fiber composite material, the impact resistance is excellent as a friction material for brakes, while maintaining an excellent point of light such as disc brake to be forced to a high temperature of occurrence Even if it is used as a friction material, it exhibits sufficient wear resistance even in the presence of oxygen, and it can be used continuously without the need for frequent replacement work like C / C composite. Thus, the inventors have found that the above object can be achieved and completed the present invention.

The fiber composite material constituting the brake friction material according to the present invention (hereinafter also referred to simply as a brake member) is a three-dimensional combination of Si-SiC-based matrices and integrated so as not to separate from each other. It is integrally formed between the yarn aggregates made of the carbon fibers formed. As will be described later, when a matrix layer formed of a Si—SiC-based material is provided, the thickness is preferably at least 0.01 mm. Furthermore, it is preferably at least 0.05 mm or more, and more preferably at least 0.1 mm or more.
Further, in the fiber composite material constituting the brake friction material, the fiber composite material preferably has a gradient composition in which the content ratio of silicon increases as the matrix moves away from the yarn. One or more substances selected from the group consisting of boron, boron, copper, bismuth, titanium, chromium, tungsten and molybdenum may be contained. The brake friction material preferably has a dynamic friction coefficient at room temperature of 0.05 to 0.6. It is preferable that the dynamic friction coefficient rises rapidly as the operating temperature rises as compared to normal temperature.

The brake member of the present invention is remarkably excellent in wear resistance under high temperature conditions in the presence of oxygen, and has a layer made of Si-SiC material having oxidation resistance, creep resistance and spalling resistance on the surface. Therefore, the low oxidation resistance of the C / C composite can be overcome, and it can be used even at high temperatures and in the presence of oxygen. It also has excellent wear resistance.
Further, since the C / C composite is used as a base material, it is lightweight, has little energy loss, and meets the demand for energy saving.
Furthermore, since the base material is a C / C composite, it is rich in toughness and has excellent impact resistance and high hardness.

  The brake friction material of the present invention is configured using a composite material made of ceramics, metal, and carbon in which a base material made of C / C composite is provided with a layer made of Si-SiC material.

Hereinafter, the novel fiber composite material used for the brake friction material of the present invention will be described.
This is a new concept material based on a so-called C / C composite, with the basic structure improved.
As a C / C composite used as a basic material, a carbon bundle having a diameter of about 10 μm is usually bundled from several hundred to several tens of thousands to form a fiber bundle (yarn), and the fiber bundle is two-dimensional or three-dimensional. A pre-formed body (fiber preform) having a predetermined shape is formed by arranging in a direction to form a unidirectional sheet (UD sheet) or various cloths, or by laminating the above-described sheets or cloths. What is known as a C / C composite formed by forming a matrix made of carbon by the CVI method (Chemical Vapor Infiltration) or inorganic polymer impregnation sintering method is used inside That's fine. In the C / C composite used in the present invention, the carbon component other than the carbon fiber in the yarn is preferably a carbon powder, and particularly preferably a graphitized carbon powder.

  The fiber composite material used in the present invention uses a C / C composite as a base material, and has a great feature that the structure of the carbon fiber is maintained without being broken. . And it has the microstructure which filled the matrix which consists of Si-SiC type material between the adjacent yarns in a yarn assembly.

  In the present invention, the Si—SiC-based material is a generic name for materials containing silicon and silicon carbide as main components, and this Si—SiC-based material is manufactured as follows. In the present invention, silicon is impregnated into a C / C composite or a molded body thereof. At this time, silicon is a carbon atom constituting carbon fiber in the composite and / or free carbon remaining on the surface of the carbon fiber. Since it reacts with atoms and is partially carbonized, silicon that is partially carbonized is formed between the outermost surface of the C / C composite and the yarn made of carbon fiber. A matrix containing carbonized silicon is formed between the yarns. This matrix may contain several different phases, from a silicon phase in which substantially pure silicon remains to a substantially pure silicon carbide phase. That is, this matrix is typically composed of a silicon phase and a silicon carbide phase, but Si— in which the carbon content changes in a gradient manner based on silicon between the silicon phase and the silicon carbide phase. A SiC coexisting phase may be included. Therefore, the Si—SiC-based material is a generic name for materials in which the carbon concentration changes from 0 mol% to 50 mol% in such a Si—SiC series.

In the fiber composite material used as a raw material for the brake friction material according to the present invention, the matrix preferably includes a silicon carbide phase generated along the surface of the yarn. In this case, the strength of each yarn itself is further improved and it is difficult to break.
The fiber composite material preferably includes a silicon phase whose matrix is made of silicon, and a silicon carbide phase is generated between the silicon phase and the yarn. In this case, the surface of the yarn is strengthened by the silicon carbide phase, and the central portion of the matrix is made of the silicon phase having a relatively low hardness, so that the microscopic stress distribution is further promoted.

The fiber composite material preferably has a matrix having a gradient composition in which the content ratio of silicon increases as the distance from the surface of the yarn increases.
In the fiber composite material, preferably, the yarn assembly includes a plurality of yarn arrays, and each yarn array is formed by two-dimensionally arranging a plurality of yarns substantially in parallel. Each yarn array is stacked to form a yarn assembly. As a result, the fiber composite material has a laminated structure in which a plurality of yarn arrays are laminated in one direction.

In this case, it is particularly preferable that the longitudinal directions of the yarns in adjacent yarn arrays intersect each other. This further promotes stress dispersion. The longitudinal directions of the yarns in adjacent yarn arrays are particularly preferably orthogonal.
Preferably, the matrix is continuous with each other in the fiber composite material to form a three-dimensional network structure. Particularly preferably in this case, the matrix is arranged two-dimensionally in parallel in each yarn array, and the matrices generated in each adjacent yarn array are continuous with each other, whereby the matrix is A three-dimensional lattice is formed.
Further, the gap between adjacent yarns may be filled with 100% matrix, but includes the case where a part of the gap between yarns is filled with the matrix.

The brake member according to the present invention has a matrix as a matrix between a base material made of a specific amount of C / C composite manufactured as described above, and the yarn assembly constituting the base material, the yarn and the yarn. It is manufactured from a fiber composite material composed of an Si—SiC-based material formed in an original lattice shape.
The brake friction material of the present invention has a large coefficient of dynamic friction at room temperature of 0.05 to 0.6, and a matrix layer made of a Si-SiC material having oxidation resistance, creep resistance, and spalling resistance. By disposing on the surface, the low oxidation resistance of the C / C composite can be overcome, and it can also be used as a brake friction material that is inevitably exposed to high temperatures in the presence of oxygen. The amount of wear under such conditions is 1.0% / hour or less at 500 ° C., more preferably 0.6% / hour or less. It also has excellent wear resistance.

In addition, since the C / C composite is used as a base material, it is lightweight, and even if it is mounted on a large land transportation machine, it does not substantially affect fuel consumption, does not cause any problems in energy consumption, and saves energy. It can be said that the material meets the requirements.
Furthermore, since the base material is a C / C composite, it is rich in toughness and has excellent impact resistance and high hardness. Therefore, it is possible to overcome the drawback that the high temperature wear resistance of the C / C composite is low while maintaining the characteristics of the conventionally used C / C composite.
Further, since the C / C composite has continuous open pores, Si-SiC impregnated with respect to the pores has a continuous structure and a three-dimensional network structure. Therefore, no matter which part is cut out, it has higher wear resistance than the C / C composite used as the base material, and maintains the high heat dissipation and flexibility inherent to the C / C composite. Is done.

  The C / C composite is a material formed by forming a matrix made of carbon at intervals between carbon fibers arranged in a two-dimensional or three-dimensional direction as described above, and contains 10 to 70% of carbon fibers. As long as it contains, elements other than carbon, such as boron nitride, boron, copper, bismuth, titanium, chromium, tungsten, and molybdenum, may be included.

  When a material having a matrix layer made of a Si-SiC-based material is used, the speed at which the Si-SiC material melts to become glass and protects the base material from oxygen is greater than the oxygen inside the base material. Since it is larger than diffusion, such a situation can be avoided and the base material can be protected from oxidation. That is, in the case of the brake member according to the present invention, it exhibits self-repairing property and can be used for a longer period of time. This effect is effective even if Si contains the third component such as boron nitride, copper, or bismuth described above.

  Furthermore, since the SiC material has a thermal expansion coefficient larger than that of the C / C composite, the layer made of the SiC material may be peeled off when used under a high temperature generated by braking for a long time, whereas the Si-SiC Since the thermal expansion coefficient of the system material is about the same as that of the C / C composite, it is possible to prevent peeling due to the difference in the thermal expansion coefficient and to have excellent characteristics as a brake member. .

The fiber composite material used in the present invention will be further described with reference to the drawings.
1 is a schematic perspective view for explaining the concept of a yarn assembly, FIG. 2 (a) is a sectional view taken along the line IIa-IIa in FIG. 1, and FIG. 2 (b) is a sectional view taken along line IIb-IIb in FIG. It is line sectional drawing. FIG. 3 is a partially enlarged view of FIG.
The skeleton of the fiber composite material 7 is constituted by a yarn assembly 6. The yarn assembly 6 is formed by stacking yarn arrays 1A, 1B, 1C, 1D, 1E, and 1F in the vertical direction. In each yarn array, each yarn 3 is arranged two-dimensionally, and the longitudinal direction of each yarn is substantially parallel. The longitudinal direction of each yarn in each yarn array adjacent to each other in the vertical direction is orthogonal. That is, the longitudinal directions of the yarns 2A of the yarn arrays 1A, 1C, and 1E are parallel to each other and orthogonal to the longitudinal direction of the yarns 2B of the yarn arrays 1B, 1D, and 1F.
Each yarn is composed of a fiber bundle 3 composed of carbon fibers and carbon components other than carbon fibers. By stacking the yarn arrays, a three-dimensional lattice-shaped yarn assembly 6 is formed. Each yarn is crushed during a pressure forming process as described later, and has a substantially elliptical shape.

In each yarn array 1A, 1C, 1E, a gap between adjacent yarns is filled with a matrix 8A, and each matrix 8A extends parallel to the surface of the yarn 2A. In each yarn array 1B, 1D, 1F, the gap between adjacent yarns is filled with a matrix 8B, and each matrix 8B extends along the surface of the yarn 2B in parallel therewith.
In this example, the matrixes 8A and 8B are respectively composed of silicon carbide phases 4A and 4B covering the surface of each yarn, and Si-SiC-based material phases 5A and 5B having a lower carbon content than the silicon carbide phases 4A and 4B. It is made up of. The silicon carbide phase may partially contain silicon. In this example, silicon carbide phases 4A and 4B are also generated between yarns 2A and 2B adjacent in the vertical direction.
Each matrix 8A and 8B is elongated along the surface of the yarn, and preferably extends linearly, and each matrix 8A and 8B is orthogonal to each other. The matrix 8A in the yarn arrays 1A, 1C, and 1E and the matrix 8B in the yarn arrays 1B, 1D, and 1F orthogonal thereto are continuous at the gap portions between the yarns 2A and 2B, respectively. As a result, the matrices 8A and 8B form a three-dimensional lattice as a whole.

  FIG. 4 is a partial cross-sectional perspective view schematically showing a main part of another fiber composite material constituting a brake member according to another embodiment. In this example, there is substantially no silicon carbide phase between the yarns 2A and 2B adjacent in the vertical direction. In each yarn array, matrices 8A and 8B are formed between adjacent yarns 2A and 2A or between yarns 2B and 2B, respectively. The forms of the matrices 8A and 8B are the same as the examples of FIGS. 1 to 3 except that there is no silicon carbide phase between yarns adjacent in the vertical direction. Each of the matrices 8A and 8B includes a silicon carbide phase 5C generated in contact with the surfaces of the yarns 2A and 2B, and a Si—SiC-based material phase 4C generated away from the yarn inside thereof. ing.

Each of the Si—SiC-based material phases preferably has a gradient composition in which the carbon concentration decreases as the distance from the surface of the yarn increases, or it preferably includes a silicon phase.
As shown in FIG. 5, the material for a brake member according to the present invention includes a C / C composite 15 and a matrix layer 13 generated by impregnating silicon on the surface of the C / C composite 15. It is preferable that the silicon layer 14 is formed on the surface layer of the matrix layer 13. In addition, 12 shows the range of the C / C composite main body before impregnating silicon. It is also preferable that the entire brake member of the present invention is formed from the above fiber composite material.

As shown in FIG. 5, the composite material used for the brake member of the present invention is preferably composed of a matrix layer 2 in which a layer made only of silicon is formed in the vicinity of the surface.
If the Si-SiC material is simply coated on the surface of the base material, the layer made of the Si-SiC material easily peels off due to the difference in thermal expansion coefficient between the two under high-temperature oxidation conditions. By forming as a matrix layer of a composite material, the strength in the fiber lamination direction can be increased, peeling can be prevented, and durability can be imparted to the brake member.

  Here, the thickness of the matrix layer 13 formed by impregnating the base material with the Si—SiC material is preferably at least 0.01 mm. Further, it is preferably at least 0.05 mm or more, and more preferably at least 0.1 mm or more. This is because when the thickness of the matrix layer 13 is less than 0.01 mm, the durability required as a brake member cannot be sufficiently provided under high oxidation conditions.

In the brake member of the present invention, it is preferable that the Si concentration in the matrix layer 13 decreases from the surface toward the inside.
By providing a gradient in the Si concentration in the matrix layer 13, it is possible to significantly improve the corrosion resistance and strength in a strong oxidative corrosion environment, the healing function against defects in the surface layer portion and the inner layer portion, and further due to the difference in thermal expansion coefficient. It is possible to prevent thermal stress deterioration of the material. This is because the Si concentration in the surface layer portion is relatively higher than the Si concentration in the inner layer portion, so that the generated microcracks are healed during heating and retain oxidation resistance.
The C / C composite used for the brake member of the present invention may contain one or more substances selected from the group consisting of boron nitride, boron, copper, bismuth, titanium, chromium, tungsten and molybdenum. .
Since these materials have lubricity, the lubricity of the fibers can be maintained even in the portion of the base material impregnated with the Si-SiC material by adding it to the base material made of C / C composite, and toughness Can be prevented.
For example, the boron nitride content is preferably 0.1 to 40% by weight with respect to 100% by weight of the base material made of the C / C composite. If the amount is less than 0.1% by weight, the effect of imparting lubricity by boron nitride cannot be obtained sufficiently, and if it exceeds 40% by weight, brittleness of boron nitride appears in the brake member.

  As described above, the brake member of the present invention has the impact resistance, high hardness and light weight of the C / C composite, and the oxidation resistance, spalling resistance, self-lubricating property, and abrasion resistance of the Si-SiC material. Combined with wear and other properties, and also has self-healing properties, it can withstand long-term use under high-temperature oxidation conditions. Specifically, it is suitable as a brake member in the field of large-scale land transport machinery. Can be used.

The fiber composite material used in the present invention can be preferably produced by the following method.
That is, for the bundle of carbon fibers, powdery binder pitches and cokes that eventually become free carbon and act as a matrix for the bundle of carbon fibers are included, and if necessary, phenol resin powder and the like are contained. To produce a carbon fiber bundle. A flexible coating made of a plastic such as a thermoplastic resin is formed around the carbon fiber bundle to obtain a flexible intermediate material. This flexible intermediate material is made into a yarn and laminated in the required amount as described in Japanese Patent Application No. 63-231791, and then hot-pressed at 300 to 2000 ° C. under the conditions of Changjo to 500 kg / cm ² . A molded body is obtained by molding with. Or this molded object is carbonized at 700-1200 degreeC as needed, and graphitized at 1500-3000 degreeC, and a sintered compact is obtained.

Carbon fiber is a PAN obtained by carbonizing pitch-based carbon fiber and acrylonitrile (co) polymer fiber obtained by adjusting pitch for spinning, melt spinning, infusibilization and carbonization using petroleum pitch or coal tar pitch as raw materials. Any of carbon-based carbon fibers may be used.
As the carbon precursor necessary for forming the matrix, thermosetting resins such as phenol resin and epoxy resin and tar, pitch, etc. are used, and these include cokes, metals, metal compounds, inorganic and organic compounds, etc. You may go out.

Next, the molded body or sintered body produced as described above and Si are held in a temperature range of 1100 to 1400 ° C. and a furnace pressure of 0.1 to 10 hPa for 1 hour or longer. Preferably, at this time, while flowing an inert gas of 0.1 NL per kg of the total weight of the compact or sintered body and silicon (normal liter: 1200 ° C., equivalent to 5065 liter when pressure is 0.1 hPa), A Si—SiC layer is formed on the surface of the compact or sintered body. Then, the temperature from 1450 to 2,500 ° C., preferably molten silicon to the green body or sintered body open pores inside temperature was raised to 1700 to 1800 ° C., impregnated, to form Si-SiC material. In this process, when a molded body is used, the molded body is also fired to produce a fiber composite material.

The molded body or sintered body and Si are held at a temperature of 1100 to 1400 ° C. and a pressure of 0.1 to 10 hPa for 1 hour or more, and in that case, inert per 1 kg of the total weight of the molded body or sintered body and Si It is desirable to control the gas to flow at 0.1 NL or more, preferably 1 NL or more, more preferably 10 NL or more.
In this way, by forming an inert gas atmosphere at the time of firing (ie, before the melting and impregnation of Si), the generated gas such as CO accompanying the change of the inorganic polymer or inorganic material to ceramic is removed from the firing atmosphere. Moreover, the porosity of the composite material obtained by subsequently melting and impregnating Si can be kept low by preventing the external firing atmosphere from being contaminated by O ₂ or the like in the atmosphere.

  Further, when Si is contacted and impregnated into the molded body or sintered body, the ambient temperature is raised to 1450 to 2500 ° C., preferably 1700 to 1800 ° C. In this case, the firing furnace pressure is preferably in the range of 0.1 to 10 hPa.

  As described above, when a flexible intermediate material is used and combined with silicon impregnation and melting, elongated pores tend to remain in the gap of the yarn in the molded body or sintered body, and along the elongated apertures. Thus, silicon easily penetrates into the sintered body or the molded body. In the process of permeation, silicon reacts with the carbon of the yarn and is gradually carbonized from the surface side of the yarn, so that the fiber composite material used in the present invention can be generated. In addition, according to a use, you may form the fiber composite material which has such a structure as what is called a fiber composite material layer only in a part of surface layer part of the base material which consists of C / C composites.

  The depth of the matrix layer is adjusted by the open porosity and the pore diameter of the molded body or sintered body. For example, when the thickness of the Si—SiC material layer is 0.01 to 10 mm, the open porosity at least near the surface of the molded body or sintered body is 5 to 50%, and the average pore diameter is 1 μm or more. . The open porosity of the molded body or sintered body is preferably 10 to 50%, and the average pore diameter is preferably 10 μm or more. If the open porosity is less than 5%, the binder in the molded body or sintered body cannot be removed. If the open porosity is greater than 50%, the Si-SiC material is impregnated deeply into the base material, and the composite material has a resistance to resistance. This is because the impact property is lowered.

  Further, in order to form the fiber composite material layer only on the surface of the C / C composite, it is necessary to use a molded body adjusted so that the open porosity near the surface is 0.1 to 30% during sintering. preferable.

  In order to reduce the open porosity of the molded body or sintered body from the surface to the inside, a plurality of preformed sheets made of preformed yarns having different binder pitches are arranged from the inside to the surface side. It arrange | positions and shape | molds so that a binder pitch may become large.

  When the silicon concentration in the fiber composite material layer is inclined, the sintered body adjusted so that the open porosity near the surface decreases from the surface toward the inside, or at least the open porosity near the surface The fiber composite material is manufactured using a molded body that is adjusted so as to become smaller from the surface toward the inside during sintering.

The brake member according to the present invention is manufactured by cutting the fiber composite material manufactured as described above into an appropriate size with a surface grinding machine or the like, and performing surface grinding finishing.
The brake member of the present invention can be used as a brake member for a large transport machine or the like.

EXAMPLES Next, although this invention is demonstrated in more detail using an Example, this invention is not limited to these Examples.
In addition, the composite material obtained by each example evaluated the characteristic by the method shown below.

(Evaluation method of dynamic friction coefficient)
The test piece was set on a jig and rotated at 100 rpm for 10 minutes. The mating material (SUJ, 10 mm sphere) was pressed against the test piece with a load Fp (N) of 2 kg, and the frictional force Fs (N) at that time was measured. The value of the friction coefficient was calculated by the following formula.
Friction coefficient μ = Fs / Fp

(Evaluation method of specific wear)
Set the test piece on the jig, rotate it at 100 rpm for 10 minutes, press the mating material (SUJ 10 mm ball) against the test piece with a load P of 2 kg, and calculate the weight Wa (mg) before the test and the weight Wb (mg) after the test. It was measured. From the density ρ (g / cm ³ ) of the test piece, the wear amount V (mm ³ ) was calculated by the following equation.
V = (Wa−Wb) / ρ
The specific wear amount Vs (mm ³ / (N · km)) was calculated from the wear amount V (mm ³ ), the test load P (N), and the sliding distance L (km) by the following equation.
Vs = V / (P · L)

(Oxidation resistance evaluation method)
The test piece was left in a furnace (1% O ₂ , 99% N ₂ ) at 1150 ° C., and the weight reduction rate after 200 hours was measured to evaluate the oxidation resistance.

(Method for evaluating compressive strength)
A compressive load was applied to the test piece, and the test piece was calculated according to the following formula.
Compressive strength = P / A
(In the formula, P represents the load at the maximum load, and A represents the minimum cross-sectional area of the test piece.)

(Weight reduction rate under high temperature oxidation conditions)
After holding a predetermined amount of the test piece in the atmosphere at 400 ° C. for 100 hours, the weight is measured, and the weight after the end of the test is subtracted from the weight before the start of the test to obtain the reduced weight. Calculated as the rate of decrease with respect to weight.

(Method for evaluating interlaminar shear strength)
Three-point bending was performed with a distance four times the thickness h of the test piece as the distance between the fulcrums, and the calculation was performed according to the following equation.
Interlaminar shear strength = 3P / 4bH
(In the formula, P represents the maximum bending load at the time of fracture, and b represents the width of the test piece.)

(Bending elastic modulus evaluation method)
A three-point bending was performed with a distance 40 times the thickness h of the test piece as the distance L between fulcrums, and the initial slope P / σ of the linear portion of the load-deflection curve was used to calculate the following equation.
Flexural modulus = 1/4 · L ³ / bh ³ · P / σ
(In the formula, b represents the width of the test piece.)

(Self-healing evaluation method)
A repetitive stress of Max: 20 MPa to Min: 5 MPa was applied 100,000 times to generate microcracks inside, and then annealed at 900 ° C. for 2 hours in an argon atmosphere to measure the compressive strength.

(5% weight loss temperature measurement method)
While giving a sufficient air flow in the atmosphere, measuring the change in the weight of the sample while raising the temperature at a rate of 10 ° C./min, the temperature at which the weight of the sample shows a 5% decrease is determined.

Example 1
A fiber composite material in which a matrix layer made of a Si—SiC-based material was arranged on a C / C composite base material having a thickness of 10 mm was manufactured, and a brake member was manufactured using this. The thickness from the surface of the fiber composite material layer formed by impregnating the base material with the Si—SiC-based material was 50 μm.
The C / C composite was produced by the following method.
A prepreg sheet impregnated with a phenolic resin in which carbon fibers were aligned in one direction was laminated so that the carbon fibers were orthogonal to each other, and the resin was cured by hot pressing at 180 ° C. and 10 kg / cm ² . Subsequently, it was fired at 2000 ° C. in nitrogen to obtain a C / C composite having a density of 1.0 g / cm ³ and an open porosity of 50%.

  Next, the obtained C / C composite was installed in a carbon crucible filled with Si powder having a purity of 99.8% and an average particle diameter of 1 mm. Next, the carbon crucible was moved into the firing furnace. The temperature in the firing furnace is 1300 ° C., the argon gas flow rate is 20 NL / min as an inert gas, the firing furnace pressure is 1 hPa, and the holding time is 4 hours. By raising the temperature to 1600 ° C., a C / C composite was impregnated with Si to produce a composite material.

  A test piece is cut out from the above-mentioned composite material from the vicinity of the surface of the C / C composite where the Si-SiC material and the C / C composite are sufficiently composited, and is 60 mm long, 60 mm wide, and 5 mm thick by a surface grinder. Then, the surface was ground with an 800 # grindstone to obtain a brake member. The surface roughness of the obtained sliding material on the ground surface was Ra = 1 μm, and the flatness was 2 μm in straightness.

  Measurement of friction coefficient, specific wear amount, oxidation resistance, interlaminar shear strength, compressive strength, flexural modulus, wear resistance under high-temperature oxidation conditions, 5% weight loss temperature, etc. The results are shown in Table 1. FIG. 6 is a chart showing the relationship between temperature and weight loss when the 5% weight loss temperature is measured. Here, the friction coefficient of the material was a value in a direction parallel to the fiber lamination direction.

(Comparative Example 1)
A C / C composite was produced in the same manner as in Example 1. The obtained C / C composite was cut into a size of 60 mm in length, 60 mm in width, and 5 mm in thickness with a surface grinder, and then surface ground with an 800 # grindstone to obtain a brake member. The surface roughness on the ground surface of the obtained brake member was Ra = 25 μm, and the flatness was 6 μm in straightness. The performance of the obtained brake member was evaluated by the same method as in Example 1, and the results are also shown in Table 1.

  From Table 1, a yarn assembly containing at least a bundle of carbon fibers and a carbon component other than carbon fibers is three-dimensionally combined and integrated so as not to separate from each other, and in this yarn assembly, A brake member made of a fiber composite material including a matrix made of a Si—SiC-based material, which is filled between adjacent yarns, is a C / C composite material conventionally used as a brake member. It can be seen that the wear resistance under high temperature conditions in the presence of oxygen is remarkably excellent.

It can be seen that the specific wear amount of the brake member according to the present invention is 1/5 or less as compared with the C / C composite of Comparative Example 1. Furthermore, compared with the C / C composite, the compression strength and the interlaminar shear strength were excellent, and the flexural modulus was similar to that of the C / C composite.
By impregnating the Si-SiC material, the compressive strength is increased as compared with the C / C composite because the SiC material enters between the carbon fibers.

  It is clear that the brake member of the present invention is a very promising material as a brake member in a braking device for a large transport machine that is used at a high temperature and in the presence of oxygen.

It is a perspective view which shows typically the structure of the yarn assembly which makes the basic structure of one fiber composite material used for the member for brakes of this invention. (A) is the IIa-IIa sectional view taken on the line of FIG. 1, (b) is the IIb-IIb sectional view taken on the line of FIG. FIG. 3 is a partially enlarged view of FIG. It is a fragmentary sectional perspective view which shows roughly the principal part of the fiber composite material of another aspect which can be used for the member for brakes concerning this invention. It is a schematic diagram which shows the cross-sectional structure of one fiber composite material used for the member for brakes of this invention. It is a chart which shows the relationship between temperature and weight reduction.

Explanation of symbols

1A, 1B, 1C, 1D, 1E, 1F ... yarn array, 2A ... yarn, 2B ... yarn, 3 ... fiber bundle (yarn), 4A ... silicon carbide phase, 4B ... silicon carbide phase, 4C ... silicon carbide phase, 5A ... Si-SiC-based material phase, 5B ... Si-SiC-based material phase, 5C ... Si-SiC-based material phase, 6 ... yarn aggregate, 7 ... fiber composite material, 8A ... matrix, 8B ... matrix, 11 ... fiber Composite material, 12 ... range of C / C composite body before impregnation with silicon, 13 ... fiber composite material layer, 14 ... silicon layer, 15 ... C / C composite.

Claims (1)

A flexible intermediate material is obtained by forming a film made of a thermoplastic resin around a carbon fiber bundle containing powdered binder pitch, coke and phenolic resin, and this flexible intermediate material is made into a yarn to give a predetermined amount. After being laminated, the molded body is molded by hot pressing at 300 to 2000 ° C. under the conditions of Jojo to 500 kg / cm ² , or the molded body is fired to obtain a sintered body. After maintaining the sintered body and Si at 1100 to 1400 ° C. and a furnace pressure of 0.1 to 10 hPa for 1 hour or more while flowing an inert gas of 0.1 NL or more per 1 kg of the total weight, a furnace pressure of 0.1 to by increasing the temperature to 1450-2,500 ° C. at 10 hPa, yarns containing a bundle and a carbon component other than carbon fibers of at least carbon fibers are combined three-dimensionally while being oriented in the layer direction, and separated from each other And strangely integrated with that yarn aggregates that Do from fiber composite material and a matrix of being filled, Si-SiC-based material between the yarns adjacent in the yarn assembly method of manufacturing a brake member.

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