JPH0476086A - Wet friction material - Google Patents

Abstract

PURPOSE:To obtain a friction material for automatic transmission, excellent in durability and stability by forming a constitution wherein carbon fibers alone or together with fine inorganic particles are integrally buried in a carbon matrix in a specified manner. CONSTITUTION:This wet friction material has a constitution wherein carbon fibers alone or together with fine inorganic particles are integrally buried in a carbon matrix. The carbon matrix has a mosaic structure wherein fine particles optically anisotropic when observed under a polarizing microscope uniformly agglomerate. This friction material comprises a sinter of carbon fiber reinforced carbon, in which the percentage of the separated interface between the carbon fibers and the carbon matrix is at most 10% of the whole interface and which has a density of 1.65g/cm<3> or higher. Because of a small difference between the static coefficient of friction and the dynamic coefficient of friction, this friction material can reduce the engagement shock when changing speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wet friction sensor for automatic transmissions used in hydraulic automatic transmissions such as automobiles.

[Prior Art] In hydraulic automatic transmissions of automobiles and various industrial machines, wet friction materials are used in clutches that operate in fluids such as oil. Conventionally, wet friction materials generally used include pulp fibers, asbeth 1 and other inorganic fibers mixed with powdered or granular inorganic fillers and bonded with phenolic resin. In addition, proposals have been made to improve performance by changing the composition of the compound (Special Publication No. 48-241).
No. 01, JP-A-58-77938, etc.). Unexamined Japanese Patent Publication 1986
Publication No. 165037 discloses that a composite VF of -C carbon fiber ML/carbon (hereinafter referred to as C/C fiber) is applied as a wet grinding mill.

In recent years, due to the increase in automobile engine output and the miniaturization of transmissions, performance requirements for friction materials have become stricter, and conventional wet friction materials cannot satisfy durability (wear resistance, heat resistance, etc.) and are always stable. This may cause deterioration in friction characteristics such as stiffness and shift feeling.

[Problems to be Solved by the Invention] In order to solve the above problems, when C/CvJ is used instead of the inorganic filler solidified with phenol resin, heat resistance etc. are improved. Somewhere this c/
When forming using c vJ, first stack carbon fibers in a predetermined shape, impregnate this with phenol resin,
After curing it, it is heated and carbonized to obtain a molded body of carbon/carbon composite material.

This molded body is fabricated by repeating resin immersion and carbonization several times, densifying it by CVD treatment, and graphitizing it. However, this c / c + A is brittle in itself, and volatile substances are generated during carbonization (J pores or residual ribolus are likely to occur), so when friction occurs, the 1-joint part is worn out, increasing the amount of wear and stability. There is a problem that there is a lack of (-).

The present invention, kJ, was developed in view of the above-mentioned circumstances. The purpose is to provide a wet grinding shrine.

``Means for Solving the Problems 1 The wet-type grinder for O1-71TSUKU1HERANCE transmission of the present invention engages the first plate and the second SOLETO in oil to transfer i~silk transmission to d3. The wet friction material is a wet friction material constituting the plate, and the wet friction material is composed of carbon 71 to 60% carbon, or carbon fibers, metals, and ceramics. [Considering the embedded structure, the carbon 71 wax has a mosaic structure in which optically anisotropic fine particles are uniformly densely packed when viewed with a polarizing microscope, and the carbon 71 wax has a mosaic structure in which optically anisotropic fine particles are uniformly densely packed. The ratio of the interface that is peeled off at the interface is 10% (relative to the other interface)
or less, and is characterized by being constructed of a carbon fiber-reinforced carbon sintered body having a density of 1.65 or more.

The wet friction material of the present invention can be applied between the friction surface of the first play I~ (desk plate) and the second play 1~ (play N~) in lubricating oil.
) is used to connect and isolate the grinding surface of one plate and transmit or release the rotational torque of one plate to the other plate.

This wet friction material is made of carbon fiber-reinforced carbon sintered body.

The carbon fibers constituting this carbon fiber-reinforced carbon sintered body ensure the strength of the sintered body, and may be those that exhibit anisotropy or isotropy when viewed under a polarizing microscope. The carbon fibers may be cut short fibers or long fibers. Further, the carbon fibers may be oriented in a fixed direction or randomly oriented in the matrix. carbon 1
Carbon in 11i fiber-reinforced carbon sintered body! The blending ratio of the 1i string is preferably 2 to 50% by weight, more preferably 10 to 40% by weight.

The inorganic microscopic bodies that can be a component of the carbon fiber-reinforced carbon sintered body can be composed of microscopic metals and ceramics.

These inorganic microscopic bodies can be in the form of powder, I-strings such as whiskers, pieces of foil, etc. The blending ratio of the inorganic microscopic carbon fiber-reinforced carbon sintered body is preferably 3 to 30% by weight, more preferably 5 to 10% by weight.

The carbon 7 trix, which is a component of the carbon fiber-reinforced carbon sintered body, has an 1E1 Ike structure in which optically anisotropic fine particles are uniformly densely packed when viewed under a polarizing microscope.

When observed under a polarizing microscope, optical anisotropy is thought to be due to carbon having a structure regularly arranged in a certain direction.

That is, this carbon matrix IJ5 is in a state in which carbon particles having optical anisotropy are compacted in a dense state. Uniformly densely packed means that the carbon particles are not flowing;
This means that there are no patterns such as flow lines. The size of carbon particles observed in a zaic shape under a polarizing microscope is preferably 30 μm or less.

The peeled area of the interface between the carbon fibers and the carbon 7 trix that constitute the carbon wI string-reinforced carbon sintered body of the present invention is such that the peeled interface area is less than % of the total interface area. There is a need to do so. If the carbon 71~lix and the carbon fibers are separated, the reinforcing effect of the carbon fibers will not be fully exhibited.

Therefore, the peeled area of the interface should be set at 10% or less, preferably 3%.

This peeling between the carbon fiber and the carbon matrix can be observed and measured using a scanning electron microscope (hereinafter referred to as SEM).

Further, the porosity of this carbon fiber-reinforced carbon sintered body is preferably 0% or less. When observed under a polarizing microscope, the pores in this sintered body are observed as black dots. Therefore, the porosity of pores can be calculated by the area of the black dots occupying the observed area.

The density of the carbon HME-reinforced carbon sintered body according to the present invention is 1.
A value of 65 or higher is a combination of characteristics such as denseness of the carbon matrix, few pores, and no peeling at the interface between the carbon fiber and the carbon 71 hex. Once upon a time, 7
1 - If the density of the wax is lacking, the porosity is too high, or there is a lot of peeling between the 111i navy blue and the 71 wax,
The specific gravity will be 1.65 or less.

This carbon fiber-reinforced carbon sintered body is characterized by direct mechanical changes such as the composition ratio of the carbon fibers, the material composition ratio of the inorganic particles, the ratio of the peeled area between the carbon fibers and the carbon matrix, and the porosity. Affects strength. When the mechanical properties of this carbon fiber-reinforced carbon sintered body are defined by bending strength, the bending strength of this sintered body is preferably 600 kg/cri or more.

The carbon fiber-reinforced carbon sintered body of the present invention is a composite body made of a self-sintering carbonaceous powder in which uncarbonized carbonaceous fibers or uncarbonized carbonaceous fibers and inorganic microscopic bodies are embedded. A sintered body obtained by sintering can be used.

Here, the uncarbonized carbonaceous fiber refers to a carbonaceous fiber that has not been subjected to normal carbonization treatment. In other words, it refers to carbonaceous fibers that can be carbonized by rough heat treatment. Specifically, when pitch is used as a raw material, the as-spun fiber or the spun fiber is
It refers to fibers that are infusible at temperatures not exceeding 0'C. PAN
(For polymer-based fibers such as polyacrylonitrile and rayon-based fibers, this refers to fibers that have undergone a decomposition process and have not yet been graphitized.This type of carbon fiber includes, for example, coal-based or petroleum-based raw material pitch. Examples include pitch fibers obtained by spinning and infusible fibers obtained by infusibleizing the pitch fibers.

The spinning a3 and infusibility of this raw material Vidge may be carried out according to a conventional method, and the length of the strips 141 etc. are not particularly limited. Normally, pitch fiber is produced by supplying raw material pitch to a spinning machine,
It can be obtained by extruding from a nozzle under pressure with inert dregs while heated to about ~400'C. In addition, such pitch fibers can be roughly heated to 150 to 50% in an oxidizing atmosphere.
It can be maintained at a temperature of about 00'C for about 0.5 to 5 hours to form an infusible fiber. In addition, this raw material pitch is
The fiber length of the 3° uncarbonized carbonaceous fiber, which may be optically isotropic or optically anisotropic, is not particularly limited to short fibers or long fibers. However, in the case of short fibers, 0
．． 01 to 50 mm can be used. Particularly, 0.03 to 10# is preferable from the viewpoint of ease of mixing and aspect ratio. If the length is too long, the fibers will become entangled with each other, resulting in poor dispersibility, which in turn will result in poor isotropy of product properties.
Moreover, if it is shorter than 0°01 m, the strength of the product will drop rapidly, which is not preferable. In addition, the fiber diameter is 5 to 25μ
It is preferable to have a diameter of about m. Furthermore, these fibers can also be used as nonwoven fabrics or coated fabrics.

Preferably, the uncarbonized carbon fibers are further surface-treated with a material containing a caking component such as tar, pitch, or organic polymer to improve compatibility with the binder. This surface treatment can be carried out by adding 100 to 1000 parts by weight of a material containing a sticky component to 100 parts by weight of carbonaceous fibers, stirring the mixture, washing with an organic solvent, and drying.

The tar and pitch used for this surface treatment are both coal-based and petroleum-based. When pitch is used, heating to about 140 to 170'C is required during stirring, so tar is more preferable for treatment (Δ), and carbonization in the subsequent carbonization and graphitization steps is more preferable. From the viewpoint of yield, coal-based materials are more preferable.

Examples of organic polymers used for this surface treatment include phenolic resins, polyvinyl chloride, and polyvinyl alcohols.

As the organic solvent used for cleaning in the above surface treatment, aromatic solvents such as toluene and xylene can be used. The organic solvent is added in an amount of about 100 to 1000 parts by weight to 100 parts by weight of the mixture of the uncarbonized carbon fiber and the adhesive component-containing material, and the mixture is crushed and washed. This washing removes light oils containing many volatile components. The uncarbonized carbonaceous fibers that have been washed are dried under conditions such as heating and/or reduced pressure in a non-oxidizing atmosphere such as nitrogen or argon. The drying process is not limited to these methods.

Furthermore, the uncarbonized carbonaceous fibers that have been dried and surface-treated are subjected to a dispersion treatment, if necessary. In other words, the dried fibers may be lumped or aggregated, so in such cases, dispersion should be carried out by any means such as a normal powder mill, a hemizer, a bulbarizer, etc. Let's do it.

The inorganic microscopic bodies together with the uncarbonized carbonaceous fibers serve as raw materials for the carbon fiber-reinforced carbon sintered body of the present invention. This inorganic microscopic body is
It is added to keep the friction coefficient μ of the friction tree low and stable, and to provide high wear resistance and high seizure resistance even with a relatively high friction coefficient μ. . The inorganic fine particles have a melting point of 1000'C or more and do not react with carbon, and more preferably have a HV of 1000 or more.

Examples of such inorganic substances include inorganic oxides, inorganic carbides, and inorganic nitrides. Examples of inorganic oxides include △, f! 203, TiO2, ZrO2, MQO
I can list many things. Examples of inorganic carbides include Cl 1c, Cl 1/r''C, etc. Examples of inorganic nitrides include Cl IN, Cr2N, Cl 1/r''C, etc.
N, A, fJ N, Z rN, etc. can be mentioned. Rani, Fe, Mn, MOLNi, Nb, 3i,
V, King i% W% Any inorganic material can be used. Note that these inorganic substances can also be added in the form of metals. Furthermore, inorganic microscopic bodies include whiskers and ceramic fibers in addition to fine particles.

By selecting an appropriate one from among the inorganic fine particles described above, the friction coefficient μ, wear resistance characteristics, anti-seizure characteristics, etc. of the friction tip can be controlled to a suitable state.

When inorganic powder is used as the inorganic particles, the particle size should be 0.1 to 5 μm, taking into consideration its compatibility with the matrix material, dispersibility, and the strength and wear resistance of the finished sintered body. The thickness is preferably 0.2 to 4 μm, more preferably 0.2 to 4 μm.

In addition, when inorganic fibers are used as the inorganic microscopic bodies, the diameter is 0.0000. 7-4C1m, length 0°01-8mm is preferable, J, more preferably diameter 1-15μm, length 0.
05-3mm.

The carbonaceous powder constitutes the binding material of the carbon fiber-reinforced carbon sintered body of the present invention. This carbonaceous powder has self-sintering properties and is uncarbonized or not completely carbonized. The self-sintering carbonaceous powder may be petroleum-based or coal-based, and specifically includes mesocarbon microbeads, bulk meso-noise pulverized products,
Examples include pulverized products of low-temperature calcined coke. Among these, petroleum-based and coal-based mesocarbon microbeads are preferred from the viewpoint of particle size 13, compositional uniformity, stability, etc., and coal-based mesocarbon microbeads are more preferred from the viewpoint of carbonization yield. As self-sintering carbonaceous powder,
Preferably, the particle size is 30 μm or less and the amount of β-resin is about 3 to 50%. In addition, this amount of β-resin is more preferably 6 to 30%, still more preferably 8 to 25%.

The sintered body of the present invention can be produced by a simple process of, for example, dry mixing uncarbonized carbon fibers, inorganic powder or inorganic fibers, and self-sintering carbonaceous powder, then press-molding and firing the mixture. Can be manufactured. Then, if necessary, it is machined to produce a -C finished product.

Uncarbonized carbon fibers, inorganic powders, [J, inorganic fibers,
The self-sintering carbonaceous powder is mixed and molded to form a composite. The mixing means at this time is not particularly limited, or
In order to make the strength and abrasion resistance uniform, it is best to uniformly mix the raw materials mentioned above. Further, the blending ratio of the self-sintering carbonaceous powder and the uncarbonized carbonaceous fiber is about 2-70 parts by weight per 100 parts by weight of the former, and more preferably about 2-70 parts by weight of the latter per 100 parts by weight of the former. It is about 10 to 50 heavy hanging parts. Further, the amount of the inorganic fine particles added is preferably 3 to 30% by weight, more preferably 5 to 10% by weight when the weight of the inorganic particles is 100%.

The sintered body according to the present invention can be formed by a conventional method, and is usually formed into a predetermined shape by applying an additive of about 1 to i Q ton / cI7i. Or The molding may be carried out by the , CIP method, l-11P method, Hola 1 to press method, etc.The molding may be carried out by heating at room temperature or in an inert atmosphere to a temperature of about 00°C. I can do it.

The molded body is sintered to become a sintered body according to the present invention. Note that sintering here means 700~・2o o o at normal pressure.
It refers to carbonizing and solidifying uncarbonized carbonaceous fibers and self-sintering carbonaceous powder by sintering at a temperature of about 'c. In addition,
If necessary, this carbonized composite may be graphitized by heating it to the sintering temperature in a graphitizing furnace. The carbonization conditions are not particularly limited, but usually 0.1-
・From room temperature to 1500℃ at a heating rate of about 300'C/hour
It is sufficient to raise the temperature to about 'C' and wait for about 0.5 to 10 hours. Note that during sintering, by sintering at a higher temperature, a part of the composite is carbonized and then graphitized.

Furthermore, the conditions for graphitization are not particularly limited, and the temperature is raised from the temperature during sintering in a non-oxidizing atmosphere to a temperature of about 1500 to 3000'C at a heating rate of about 0.1 to 500°C/hour. Just warm it up and wait for about 0.5 to 10 hours. When graphitized, graphite crystals significantly improve the density, strength, and wear resistance of the product.

This special carbon fiber-reinforced carbon sintered body consists of a compact before sintering made of uncarbonized carbon fibers and inorganic powder or uncarbonized carbonaceous powder with self-sintering properties embedded with inorganic fibers. There is C. In the past, when sintering a molded body,
The carbonaceous fiber used as a reinforcing material is either uncarbonized or not completely carbonized, so this uncarbonized carbonaceous fiber and the uncarbonized carbonaceous fiber that determines self-sintering properties differ when carbonized. They have similar physical properties (strength, shrinkage rate, etc.).

Therefore, the interfacial adhesion between these carbonaceous fibers and the carbonaceous powder is improved, making it possible to obtain high strength and excellent wear resistance. In short, when a compact is sintered, uncarbonized carbon fibers and carbon powder h) shrink to the same degree and bond together, increasing their interfacial adhesion and improving the strength and wear resistance of the friction material. or improve.

In addition, parts made of carbon fiber-reinforced carbon sintered bodies with inorganic powder or inorganic fibers have a mechanical resistance between them and the other material, which results in a high coefficient of friction μ and stability. Become. In other words, the added inorganic powder or inorganic fiber does not exert mechanical resistance on the mating material.
The friction coefficient μ of the friction material is high and stable.

For example, when inorganic powder is added, since it is necessarily in powder form, carbon 71 tends to separate from the wax part as the load increases, and by balancing the separation of the inorganic powder with the adhesion of the carbon matrix part, The friction coefficient μ remains stable against changes in load. Further, when inorganic fibers are added, even if the load increases, since they are fibrous, they are difficult to separate from the carbon 71 to lix portion, and therefore the friction coefficient μ becomes a high value.

Furthermore, as described above, the self-sintering carbonaceous powder as a binder eliminates the need for a conventional binder consisting of liquid carbonaceous material. Therefore, there is no need to repeat impregnation and firing in order to fill the pores caused by the use of a liquid binder. The special carbon fiber reinforced carbon sintered body according to the present invention is
As described in 7j above, it can be manufactured at low cost by a simple two-step process of dry mixing, pressure molding, and firing.

By selecting appropriate inorganic powders or inorganic fibers, the wear of products made from carbon fiber-reinforced carbon sintered bodies can be improved.
The detection coefficient μ can be managed to a suitable value depending on the application. When the inorganic powder is an inorganic carbide, the friction coefficient μ of the friction material can be controlled within the range of 0.15 to 0.35, and when the inorganic powder is an inorganic nitride, the friction coefficient μ of 1 g of abrasion If the inorganic powder is an oxide, the friction coefficient μ of the friction material should be controlled within the range of 0.25 to 0.5. You can cover it.

The reason why the coefficient of friction μ of the friction plate changes greatly depending on the inorganic powder or fibers added is thought to be because the state of the inorganic powder or fibers changes due to the heat generated by friction. For example, since oxides have high heat resistance, they remain in the form of particles or fibers even during friction, and are therefore thought to exhibit a high coefficient of friction μ.

Furthermore, when uncarbonized carbonaceous fibers are surface-treated with a material containing a viscosity component such as tar, pitch, or organic polymer, the wettability of the carbonaceous fiber interface increases, which makes it difficult to use as a binder. Since the compatibility with the carbonaceous powder is improved, the interfacial adhesion between these carbonaceous fibers and the carbonaceous powder is further improved.

[Example] Hereinafter, this will be explained in detail using examples.

This friction material was produced as follows.

Uncarbonized carbonaceous fibers made of infusible fibers with a diameter of 15 μm and a length of 3# are prepared by spinning coal-based optically isotropic pitch using a conventional method.

Using this uncarbonized carbonaceous fiber as a reinforcing material, 300 parts by weight of this uncarbonized carbonaceous fiber is combined with self-sintering carbon powder 7 consisting of Luthal-based carbon microbeads with a center particle size of 7 μm.
After adding 00 parts by weight, the mixture was mixed uniformly, and the resulting mixture was shaped into a hollow disk having an outer diameter of 130/II/I+inner diameter of 100 m, and a molded body was formed using a molding pressure horn of 2 ton/cm.

Next, this molded body was heated to 1000°C at a heating rate of 150'C/hour in a non-oxidizing atmosphere, and sintered by holding at the same temperature for 1 hour. The self-sintering carbonaceous powder was carbonized and consolidated.

Then, in a non-oxidizing atmosphere, the temperature was raised to 2800'C at a heating rate of 500'C/hour and held for 20 minutes to remove NO31, which was 1°d5, this carbon, *
Using a part of the fiber-reinforced carbon sintered body, the surface was observed using a polarizing microscope, the interface state between Knox and reinforcing fibers was observed using SEM, and the density and bending strength were measured. The matrix was observed as a mosaic of sintered carbon particles with different colored patterns, and the fibers were observed as uniformly colored islands scattered throughout this 71~rix.The area of these black dots was The total area is 100
When expressed as area %, it was about 3 area %.

The state of the interface between the matrix and reinforcing fibers observed by SEM was such that they were integrally bonded, and no separation of the 71-wax and reinforcing fibers was observed. Further, the density CJ of this carbon fiber reinforced carbon sintered body, 1.
809/cm3, and the bending strength was 9°/IK9/#2.

N092 m+A was produced as follows.

Coal-based optically isotropic pitch was fed to the spinning machine, and 340
Pitch fibers obtained by extruding them from a nozzle under pressure with an inert gas while heated to 15°C are held at 350°C for 2 hours in a roughly oxidizing atmosphere to make them infusible, and the fiber diameter is 15°C.
Infusible charcoalized carbon fibers with μrT1 and a fiber length of 0.5 mm were produced. A 95% mixture of 30% by weight of infusible uncarbonized carbon fibers as a reinforcing material and 70% by weight of rutal mesocarbon microbeads with a center particle diameter of 771 m as self-sintering carbonaceous powder. However, the particle size is 4゜0
No. A mixture containing 5% by weight of μm alumina.

It was molded in the same manner as 1.

Next, this molded body is heated to 1000°C at a rate of 1 bO'C/hour in a non-oxidizing atmosphere, and kept at the same temperature for 1 hour to sinter to form uncarbonized carbon fibers and self-sinter. The carbonaceous powder was carbonized and solidified in 1, and then sintered by raising the temperature to 2000°C at a rate of 500°C/hour in a roughly non-oxidizing atmosphere and holding it for 20 minutes.

Na a3, this carbon 1. Using a part of the Ti fiber-reinforced carbon sintered body, in the same manner as in Example No. 1, the surface was observed using a polarizing microscope, the interface state of SFM was observed, and the density and bending strength were measured. When observed using a polarized light microscope, the wax or sintered carbon particles were observed to form a mosaic pattern in which the individual particles were closely intermixed with each other and had different colored patterns, and the fibers had a uniform color scattered throughout this matrix. It was observed as an island.

Also, the area of these black dots is 100% of the total area.
When closed, the area was about 3%. 71 observed with SEM
The state of the interface between the matrix and the reinforcing fibers was considered to be that they were both integrally bonded, and the matrix and reinforcing fibers were separated.

In addition, the density of this carbon fiber reinforced carbon sintered body is 1°86g.
/cm3, and the bending strength is 8.0KFi/mm2.

No. 093 was a comparative example, and a molding material based on conventional cellulose fibers was produced. This is made by making paper in water from a mixture of 50 parts by weight of cell fibers with a fiber diameter of 10 μrTl and 40 parts by weight of inorganic fillers (diatomite, potassium titanate, glass fibers) to a thickness of 0°558. A friction material was prepared by impregnating it with a phenol resin, curing it by heating, and laminating it into a predetermined shape.

(Test Example 1) Wear test This test was conducted using three friction plates (outer diameter 127#, inner diameter 108#) made by the method described in 1-1 and steel (material 5P02).
8> Put 4 separators together in silk A-F oil, 5AENo.
A friction detection engagement test was conducted using 2 test machines.

Row number 1 is rotation speed: 4000r, p, m, pressing is crab 5
00Kgf, oil temperature: 110'C1, number of repetitions: 200
This was repeated 0 times and the 1 Herc waveform generated at that time was examined. Note that in this torque waveform, the friction coefficient was calculated based on the slope of the curve. Calculations were made at the positions corresponding to the positions of a: initial friction coefficient, b: dynamic friction coefficient, and C: static friction coefficient in FIG. 1 (a>).

The torque waveforms at the initial stage and after 2000 cycles are shown in Figure 1 (
Shown in a>(b). In addition, sideways! +I+ is the time required for engagement of 2/l, and the vertical axis is the friction force.

In the comparative example of No. 1.3, the friction force is low after the start of engagement, and the friction force increases rapidly when the engagement is completed. No. 1.2 shows a flat curve until engagement. Even when the engagement is completed, it does not take on a sharp shape as in the comparative example, but instead has a gentle curve. 6, smooth engagement is possible.

For conventional valves and base material No. 3 friction plate, initial a3
The coefficient of static friction/coefficient of dynamic friction is 1.0 or more for both No. and 2000 cycles, and the feeling is worse due to the influence of gear change shock during engagement, whereas No. 1 of Example, No. 1. In both of the friction plates No. 2, the coefficient of static friction/coefficient of dynamic friction is close to 1.0, allowing smooth engagement.

In the comparative example after the durability test of 20001 No-Ikuru, the level of the dynamic friction coefficient was low and the engagement time was long.
In the examples, even after durability, the level of the dynamic friction coefficient is almost constant, indicating stable engagement.

Further, in the case of the example, since the friction coefficient is higher than that of the comparative example, the engagement time with the body surface is shorter.

FIG. 2 shows the amount of wear after J, 2000I Nikle durability test. In Comparative Example No. 3, the surface was carbonized and partially peeled off, showing a large amount of wear, but it was removed.

Examples 1 and 2 show excellent durability with little wear.

With friction materials No. 3, after repeated durability tests, the friction material becomes stuck in a porous state or becomes clogged, the coefficient of dynamic friction decreases, and the engagement time becomes longer.

Also, the coefficient of static friction does not change much - the shock of CC shifting increases.

(Test Example 2) The above friction plate was tested on an actual 71"-1~Magic Transmission (overdrive (=j-A/K) for
The assembly was completed through d3 friction tests on the actual machine.

The test conditions were to increase sequentially from 1 to 4 descent with full throttle and 1 hell, then decrease from 4 to 1]-h at throttle opening 0% for 3000 cycles of Nycle (120 seconds/1 cycle). carried out. Figure 3 shows the change in the shift time from 1st to 2nd speed at G.

This figure shows that in the comparative example No. 3, it takes time to shift initially, and as the number of cycles increases, the time gradually becomes shorter, reaches the lowest point at first glance, and then becomes longer again.-C
There is. In contrast to this, where the shift time changes depending on the number of cycles, the shift time of Example C2 is constant and stable from the initial stage to 3000 cycles. That is, the friction plate of Example [1] always has a stable shift feeling.

(Test Example 3) Furthermore, the carbon fiber reinforced carbon sintered body of Example No. 2 (S
Test pieces were prepared by varying the type and maximum (5%, 10%) of ceramic powder as inorganic microspheres mixed in T30), and the wear amount and friction coefficient were measured using a 1-FW friction wear tester. The measuring strip '1 is a 5-piece wire with an outer diameter of 35 mm, an inner diameter of 31 mm, and a length of 8.7 in the axial direction.
Using a UJ2 ring, using S to F standard 5W-30 base oil as the lubricant, -C rotation speed 160 times/
Separately, the length is 15.7 mm and the width is 6.3 m on the outer peripheral surface of the mating material.
m, a test piece with a height of 10 m was pressurized with a load of 15 kgf, and 1
It was allowed to slide for 5 minutes. The results are shown in FIGS. 4(a) to 4(d).

In Figure 4, the bar graph shows the amount of wear on the test piece, and the number for the old capital is the coefficient of friction. Carbon aIi fiber reinforced carbon sintered body (ST
30) The amount of wear and friction coefficient can be changed by appropriately selecting the amount of ceramics added, particle size, etc. Therefore, this carbon fiber-reinforced carbon sintered body can be made into a material with predetermined physical properties depending on the type and amount of ceramics.

[Effects of the Invention] The wet friction material of the present invention is made of a special carbon fiber-reinforced carbon sintered body. This carbon fiber-reinforced carbon sintered body has high strength, low wear, and stable friction characteristics.

Furthermore, the friction coefficient can be easily controlled to a predetermined value by adding inorganic particles. Furthermore, this friction ∆ has a small difference between the static friction coefficient and the dynamic friction coefficient 1. Therefore, engagement shock during gear shifting can be reduced. Therefore, smooth gear shifting is possible and good shift 1 feeling is achieved.

In addition, since the friction coefficient is larger than that of conventional materials, the time during engagement is short and stable, and the friction coefficient (Δ) is excellent and lightweight.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are the initial stage of the friction test, 200
A graph showing the torque waveform after 0-recycling, Fig. 2 is a bar graph showing the amount of wear on the friction plate, and Fig. 3 is a graph showing the amount of wear on the friction plate.
The graphs of the shift time for each cycle, FIGS. 4(a) to 4(d), are bar graphs showing the friction coefficient and wear amount of carbon 11li fiber-reinforced carbon sintered blocks with different types of inorganic particles. Tokumu'F Applicant 1 - Yota Motors Co., Ltd.
Osaka Gas Co., Ltd.

Claims (2)

[Claims] (1) A wet friction material that constitutes a plate that transmits torque by engaging a first plate and a second plate in oil, the wet friction material having carbon fibers or carbon in a carbon matrix. The carbon matrix has a structure in which fibers and inorganic microscopic bodies are embedded integrally, and the carbon matrix has a mosaic structure in which optically anisotropic fine particles are uniformly densely packed when viewed under a polarizing microscope. The carbon fiber-reinforced carbon sintered body has a ratio of peeled interfaces of 10% or less of all interfaces and a density of 1.65 or more. wet friction material. (2) A wet friction material that constitutes a plate that transmits torque by engaging a first plate and a second plate in oil, the wet friction material comprising uncarbonized carbon fibers or uncarbonized carbon fibers. A wet method characterized by being composed of a carbon fiber-reinforced carbon sintered body obtained by sintering a composite body made of carbonaceous powder having a self-sintered body in which carbonized carbonaceous fibers and inorganic microscopic bodies are embedded. Friction material.