JP2007039556A - Friction material set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combination between a friction material having a high friction coefficient and excellent wear resistance and a partner material. <P>SOLUTION: A friction material set comprises a friction material 2 and a partner material 3 and generates a braking force by a frictional force produced between the friction material 2 and the partner material 3. The friction material 2 includes a fibrous substrate, a friction regulator and a binding agent which is an organic substance and contains an SiC fiber 2a as the friction regulator. Not less than 80 vol% of the SiC fiber 2a are oriented at an angle of 40-140° to the partner material 3. The partner material 3 has a cermet layer 3a on its surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a friction material set having a friction material and a counterpart material, and generating a braking force by a friction force generated between the friction material and the counterpart material.

The friction material set has conventionally been improved in friction coefficient, which is a basic characteristic, and in wear resistance. Attempts have been made to reduce the size and weight of the friction material set by improving both characteristics.
However, the improvement of the coefficient of friction and the improvement of the wear resistance are complementary to each other. For example, when the grinding force of the friction material is increased to increase the friction coefficient, there arises a problem that the wear amount of the counterpart material increases. When the friction coefficient is increased by adding a large amount of metal raw material to the friction material to increase the adhesion force, there arises a problem that the temperature dependence of the friction coefficient is large and seizure is likely to occur.

In order to solve these problems, various friction materials and counterpart materials have been developed.
For example, the friction material which concerns on patent document 1 has a silicon carbide which raises a friction coefficient, and the inorganic substance which improves lubricity. In order to obtain an appropriate friction coefficient and an appropriate wear resistance, the amount of silicon carbide is set to 10 to 30% by weight. However, with this friction material, a sufficiently high friction coefficient could not be obtained.
Patent Document 2 discloses a rotor (a counterpart material). The rotor has a hard cermet layer on the surface, thereby improving wear resistance. However, since the surface of the rotor is hard, there is a problem that a sufficiently high friction coefficient cannot be obtained unless a friction material slidingly contacted with the rotor is selected. Nevertheless, Patent Document 2 does not disclose a suitable friction material for the rotor.

  Patent Document 3 discloses a combination of a friction material and a counterpart material. That is, a combination is disclosed in which one is a carbon-carbon composite material and the other is a composite material in which silicon carbide is reinforced with a fibrous reinforcing material. Further, it is disclosed that, by using this combination, the friction coefficient is higher than that of a combination of carbon-carbon composite materials, and it can be configured at low cost. However, the friction material set of this combination has a problem that the amount of wear on the carbon-carbon composite material side becomes very large. Moreover, the friction material and the counterpart material described in Patent Document 3 have been developed for racing or aircraft, and are based on carbon or silicon carbide. Therefore, the friction material set according to the present invention including the friction material having the fiber base material, the friction modifier, and the organic binder as in the present invention is greatly different in material.

Patent Document 4 discloses a friction material. The friction material is made of a ceramic matrix composite material, and is made of a material in which boron carbide is reinforced with non-oxide ceramic fibers. This improves the wear resistance of the friction material. However, the friction material described in Patent Document 4 is used for racing or aircraft, and is based on ceramic. Therefore, the friction material according to Patent Document 4 is greatly different from the present invention in materials.
JP 2004-35871 A JP 2001-317573 A Japanese Patent Publication No. 7-68991 Japanese translation of PCT publication No. 2004-510474

  Therefore, the present invention provides a friction material set having a friction coefficient and a high wear resistance in a friction material set having a friction material and a counterpart material, and the friction material has a fiber base material, a friction modifier, and an organic binder. The issue is to provide.

In order to solve the above-mentioned problems, the present invention is a friction material set having a configuration as described in each claim.
That is, according to the first aspect of the present invention, the friction material has a fiber base material, a friction modifier, and an organic binder, and includes SiC fibers as the friction modifier. And 80 volume% or more of the SiC fibers are oriented at an angle of 40 ° to 140 ° with respect to the counterpart material. The counterpart material has a cermet layer on the surface.

  Therefore, since the friction material contains very hard SiC fibers, a high friction coefficient is generated between the friction material and the counterpart material. Moreover, since the SiC fiber is fibrous, it has a larger surface area in contact with the matrix than in the case of granular. For this reason, the SiC fiber is strongly held by the matrix, and is not easily detached from the matrix (not easily removed). In particular, at a high temperature (high load) or after a high temperature history, the matrix becomes fragile because it contains an organic binder, but even under such circumstances, the SiC fibers are not easily detached from the matrix. Therefore, the friction material has high wear resistance due to the SiC fiber, and particularly has high wear resistance at high temperatures.

Moreover, the SiC fibers are oriented at an angle of 40 ° to 140 ° with respect to the counterpart material. It was found from experimental results that the friction coefficient is sufficiently increased by setting the orientation angle of the SiC fiber to 40 ° to 140 °.
On the other hand, the counterpart material has a cermet layer. From the experimental results, it was found from the experimental results that the counterpart material having the cermet layer is difficult to scrape against the friction material containing SiC fibers and that the friction coefficient is sufficiently obtained.
Therefore, according to the present invention, it is possible to improve the friction coefficient and the wear resistance.

According to invention of Claim 2, 80 volume% or more of SiC fiber is orientated at 90 degrees +/- 5 degrees with respect to the other party material.
It was found from the experimental results that the friction coefficient can be further increased by this.

According to the invention described in claim 3, the SiC fiber has a fiber length of 0.5 mm to 20 mm.
Accordingly, the SiC fiber is not easily removed from the matrix because the fiber length is 0.5 mm or more. Therefore, the wear resistance of the friction material is sufficiently increased by the SiC fiber. Further, since the SiC fiber has a fiber length of 20 mm or less, it can be prevented that the SiC fiber is entangled with the mixer in the raw material mixing step which is one of the manufacturing processes. Therefore, according to the present invention, it is possible to facilitate the molding of the friction material and improve the wear resistance of the friction material.

According to invention of Claim 4, the friction material has 5-50 volume% of SiC fibers.
Therefore, the friction coefficient can be sufficiently increased by the blending amount.

According to the invention described in claim 5, the cermet layer of the counterpart material contains tungsten carbide.
From the experimental results, when tungsten carbide is included in the cermet layer, a high coefficient of friction is generated between the counterpart material and the friction material according to the present invention (see claims 1 to 4), and the resistance of both members is high. It was found that the wear resistance was high.

The friction material set 1 according to the present invention has a friction material 2 and a mating material 3 as shown in FIG. 1, and generates a braking force by the friction force generated when these are brought into sliding contact.
The friction material 2 has a fiber base material, a friction modifier (filler), and a binder as main components, and the friction modifier includes SiC fibers. As shown in FIGS. 2 and 3, the SiC fiber 2a is included in the friction material 2 in an oriented state.
On the other hand, a cermet layer 3 a is formed on the counterpart material 3. Hereinafter, the components and manufacturing methods of the friction material 2 and the counterpart material 3 will be described in detail.

As the fiber base material of the friction material 2, inorganic fibers and organic fibers can be appropriately selected and used. As the inorganic fibers, iron fibers, steel fibers, copper fibers, glass fibers, ceramic fibers (such as alumina-silica ceramic fibers), potassium titanate fibers, and the like can be used. An aramid fiber etc. can be used as an organic fiber. And although these fiber base materials can also be used individually, several types can also be mixed and used.
The fiber base material is short fiber or powder (for example, copper powder), and the added amount of the fiber base material is preferably 10 to 50% by weight of the entire friction material.

The friction modifier (filler) is included for adjusting the friction coefficient, adjusting abnormal noise, preventing rust, and the like, and inorganic fillers, organic fillers, lubricants, and the like are used as appropriate.
Examples of the inorganic filler include SiC fibers that are abrasives. In addition to SiC fibers, abrasives, barium sulfate, calcium carbonate, calcium hydroxide, mica (mica), kaolin, talc, and the like are appropriately included. As the organic filler, cashew dust, rubber dust and the like are appropriately included. Examples of the lubricant include graphite, graphite, antimony trisulfide, molybdenum disulfide, and zinc disulfide.

The SiC fiber having a diameter of 5 to 15 μm and a length of 0.5 to 20 mm, preferably having a length of 1 to 10 mm is used.
It is preferable that the addition amount of SiC fiber is 5-35 volume% of the whole friction material.
As shown in FIGS. 2 and 3, SiC fiber 2 a is included in a state of being oriented in friction material 2, and has an angle (orientation angle) α with respect to counterpart material 3.

The orientation angle α is also an angle formed between the SiC fiber 2a and the sliding direction A. Specifically, it is also an angle formed by the SiC fiber 2a and the sliding direction A on a plane (surface shown in FIGS. 2 and 3) parallel to the sliding direction A and perpendicular to the sliding surfaces of the friction material 2 and the counterpart material 3. .
The orientation angle α is 40 ° to 140 °, preferably 45 ° to 135 °, 60 ° to 120 °, more preferably 90 ° ± 5 °. And 80 volume% or more of SiC fiber 2a, Preferably 90 volume% or more has orientation angle (alpha). Roughly speaking, an average orientation angle of 8 out of 10 SiC fibers 2a included in the friction material 2 and preferably 9 or more has the orientation angle α.
Alternatively, the average orientation angle of the entire SiC fiber 2a is 40 ° to 140 °, preferably 45 ° to 135 °, 60 ° to 120 °, and more preferably 90 ° ± 5 °.

As the binder, an organic resin is used. For example, phenol resin, imide resin, rubber-modified phenol resin, melamine resin, epoxy resin, NBR, nitrile rubber, acrylic rubber and the like are used. And a binder can also be used individually by 1 type, and can also be used in combination of 2 or more type.
The addition amount of the binder is preferably 5 to 30% by volume of the entire friction material.

Next, a method for manufacturing the friction material 2 will be described.
First, the friction material raw materials are uniformly mixed in a dry process to obtain a raw material mixture. As a mixer, an Eirich mixer, a universal mixer, a Laedige mixer, or the like can be used.
Next, the raw material mixture is preformed with a preliminary mold to obtain the preform 4.
Then, as shown in FIG. 4, the preform 4 is press-heated and molded with a molding die. The molding temperature of the pressure heating molding is 130 to 200 ° C., the molding pressure is 100 to 1000 kgf / cm ² , and the molding time is 2 to 15 minutes.
Next, the molded body is thermally cured at 140 to 400 ° C. for 2 to 48 hours.

In the manufacturing process, the SiC fiber 2a can obtain orientation. That is, as shown in FIG. 4, the SiC fiber 2a does not have directivity in the preform 4 before press-heating, but is press-heated together with other raw materials as shown in FIG. As a result, it is substantially orthogonal (horizontal direction in FIG. 5) to the pressing direction (downward direction in FIG. 5). Therefore, the SiC fiber 2 a can obtain directivity in the molded body 5.
And the friction material 2 provided with the SiC fiber 2a which has a predetermined orientation angle can be obtained by cut | disconnecting the molded object 5 by a predetermined angle and obtaining the friction material 2. FIG.
Note that the timing of cutting the molded body 5 may be before or after the molded body 5 is thermally cured.
Finally, a back plate (not shown) is bonded to the back surface of the friction material 2.

The counterpart material 3 has a cermet layer 3a formed on the metal surface as shown in FIGS.
For example, the mating material 3 is a cast iron disc brake rotor as shown in FIG. 1, and is formed by spraying cermet raw material powder on the rotor surface and polishing the surface as shown in FIGS. The cermet layer 3a is provided.
The cermet raw material powder includes a metal powder such as Co and a carbonized or oxidized ceramic powder, and becomes a cermet layer 3a when sprayed. The cermet layer 3a preferably includes tungsten carbide (WC-12Co), and the thickness is preferably 50 to 1000 μm.

Hereinafter, Examples 1 to 3 and Comparative Examples 1 to 5 according to the present invention will be described using specific numbers.
The friction materials according to Examples 1 and 2 and the friction materials according to Comparative Examples 1 to 3 are formed from a raw material mixture blended in the raw material components and blending amounts shown in Table 1.

The friction material according to Examples 1 and 2 and the friction material according to Comparative Examples 2 and 3 include SiC fibers as an abrasive. On the other hand, the friction material according to Comparative Example 1 has granular SiC particles as an abrasive.
The SiC fibers included in Examples 1 and 2 and Comparative Examples 2 and 3 were those having an average diameter of 14 μm and a length of 4 mm. The SiC particles included in Comparative Example 1 were those having an average particle size of 15 μm.

  The friction material according to Examples 1 and 2 and the friction material according to Comparative Examples 2 and 3 are different in the orientation angle (α) of the SiC fiber with respect to the counterpart material. Comparative Example 2 has α = 0 ± 5 °, Comparative Example 3 has α = 30 ± 5 ° (in other words, 150 ± 5 °), and Example 1 has α = 45 ± 5 ° (as shown in FIG. In other words, in Example 2, α = 90 ± 5 ° as shown in FIG. Therefore, the SiC fiber stands up with respect to the counterpart material most in Example 2, and falls down with respect to the counterpart material in the order of Example 1, Comparative Example 3, and Comparative Example 2.

The manufacturing method of the friction material which concerns on Examples 1, 2 and Comparative Examples 1-3 is the same, Comprising: The raw material shown in Table 1 was mixed by the dry type for 5 minutes with the Eirich mixer, and the raw material mixture was obtained. The raw material mixture was pressure-heat molded at a molding temperature of 160 ° C., a molding pressure of 200 kgf / cm ² , and a molding time of 10 minutes to obtain a molded body. Thereafter, the compact was thermoset at 230 ° C. for 3 hours.
And the molded object was cut | disconnected by the desired angle so that the orientation angle of a SiC fiber might turn into a desired angle, and the friction material was obtained. The back plate was bonded to the friction material.
As a method of manufacturing the mating member, first, a rotor for disc brake made of cast iron was prepared. Then, WC-Co powder was sprayed on the rotor surface, and the surface was polished after spraying to form a cermet layer having a layer thickness of about 300 μm.

Next, each characteristic of the friction material set having the friction material and the counterpart material was measured. The measurement results are summarized in Table 2.
Each characteristic was measured as follows.
<Abrasion amount after test> According to JASO C-406-87, a measurement test of the friction coefficient of the first effect, the first fade, the second effect, the second fade, the third effect, and the third fade was performed. The wear amount of the counterpart material (rotor) and the friction material was measured.
<Friction Coefficient of Second Efficacy and Third Efficacy> The average friction coefficient and variation at a speed before braking of 50 km / h were measured according to JASO C-406-87.
<Friction coefficient of second fade> According to JASO C-406-87, the instantaneous minimum friction coefficient at the time of fade at a speed before braking of 50 km / h and the temperature at that time were measured.
<Determination> Each measurement result was determined according to the determination criteria shown in Table 3 below.
○: Satisfies all judgment criteria ×: Does not meet judgment criteria in one or more

From the measurement results in Table 2, the following were found.
In Comparative Examples 1 to 3, the friction coefficient of the second effect and the friction coefficient of the third effect were small, and it was found that the determination criteria shown in Table 3 were not satisfied.
In Examples 1 and 2 and Comparative Examples 2 and 3, it was found that the wear amount of the friction material was smaller than that in Comparative Example 1.
Therefore, it was found that the friction material containing SiC fibers has less wear than the friction material containing SiC particles.

In Examples 1 and 2, it was found that the friction coefficient of the second effect and the friction coefficient of the third effect were higher than those of Comparative Examples 1 to 3. Further, it was found that the friction coefficient (the friction coefficient of the second effect and the friction coefficient of the third effect) was highest in Example 2, and decreased in the order of Example 1, Comparative Example 1, and Comparative Example 2.
Therefore, it was found that the friction coefficient (the friction coefficient of the second effect and the friction coefficient of the third effect) becomes higher as the SiC fiber is closer to the standing state with respect to the counterpart material, that is, as the orientation angle α is closer to 90 °. . It was found that the orientation angle α exceeded the desired coefficient of friction (0.65) in the states of Examples 1 and 2, ie, α = 45 ± 5 ° and 90 ± 5 °.

Further, it was found that the wear amount of the counterpart material was sufficiently small in any of Examples 1 and 2 and Comparative Examples 1 to 3.
Therefore, even when SiC fibers with high hardness are used for the friction material and the SiC fibers are oriented at a desired angle, the wear amount of the counterpart material may be sufficiently reduced by having a cermet layer. all right.

As described above, the friction material set 1 is formed.
That is, the friction material 2 of the friction material set 1 includes the SiC fiber 2a as a friction modifier. And 80 volume% or more of the SiC fiber 2a is oriented at an angle of 40 ° to 140 ° with respect to the counterpart material 3 (see FIGS. 2 and 3). The counterpart material 3 of the friction material set 1 has a cermet layer 3a on the surface.

  Therefore, since the friction material 2 contains very hard SiC fibers, a high friction coefficient is generated between the friction material 2 and the counterpart material 3 (see Table 2). Moreover, since the SiC fiber 2a is in a fibrous form, it has a larger surface area in contact with the matrix than in the granular case. Therefore, SiC fiber 2a is strongly held by the matrix, and is difficult to be separated from the matrix (not easily removed). In particular, at a high temperature (high load) or after a high temperature history, the matrix is fragile because it contains an organic binder, but even under such circumstances, the SiC fiber 2a is not easily detached from the matrix. Therefore, the friction material 2 has high wear resistance due to the SiC fibers 2a, and particularly has high wear resistance at high temperatures.

Moreover, the SiC fiber 2a is oriented at an angle of 40 ° to 140 ° with respect to the counterpart material 3. It was found from the experimental results that the friction coefficient is sufficiently increased by setting the orientation angle of the SiC fiber 2a to 40 ° to 140 ° (see Table 2).
On the other hand, the counterpart material 3 has a cermet layer 3a. From the experimental results, it was found from the experimental results that the counterpart material 3 having the cermet layer 3a is not easily scraped against the friction material 2 including the SiC fibers 2a and that the friction coefficient is sufficiently obtained.
Therefore, according to the friction material set 1, it is possible to improve the friction coefficient and the wear resistance.

Further, it is preferable that the SiC fiber is in a form in which 80% by volume or more is oriented at 90 ° ± 5 ° with respect to the counterpart material.
It was found from the experimental results that the friction coefficient can be further increased (see Table 2).

The SiC fiber 2a has a fiber length of 0.5 mm to 20 mm.
Accordingly, the SiC fiber 2a has a fiber length of 0.5 mm or more, and thus is not easily removed from the matrix. Therefore, the wear resistance of the friction material is sufficiently increased by the SiC fiber 2a. Moreover, since the fiber length of the SiC fiber 2a is 20 mm or less, it can be prevented that the SiC fiber 2a is entangled with the mixer in the raw material mixing step which is one of the manufacturing processes. Therefore, according to this embodiment, it is possible to facilitate the molding of the friction material 2 and improve the wear resistance of the friction material 2.

Moreover, the friction material has 5-50 volume% of SiC fibers.
Therefore, the friction coefficient can be sufficiently increased by the blending amount.
Further, the cermet layer 3a of the counterpart material 3 contains tungsten carbide.
From the experimental results, when tungsten carbide is contained in the cermet layer 3a, a high coefficient of friction is generated between the counterpart material 3 and the friction material 2, and the wear resistance of both members is increased. Okay (see Table 2).

  The present invention is not limited to the friction material set used for the disk brake pad and rotor, but may be a friction material set used for other brake devices.

It is a front view of a friction material set. It is a schematic diagram of the friction material set in the II-II line of FIG. It is a schematic diagram of the friction material set in the II-II line of FIG. It is the figure which showed a mode that the preforming body was pressure-heat-molded. It is the figure which showed a mode that the molded object was cut | disconnected and a friction material was obtained.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Friction material set 2 ... Friction material 2a ... SiC fiber 3a ... Cermet layer 3 ... Opposite material 4 ... Preliminary molded object 5 ... Molded object alpha ... Orientation angle

Claims (5)

A friction material set (1) having a friction material (2) and a counterpart material (3) and generating a braking force by a friction force generated between the friction material (2) and the counterpart material (3). ,
The friction material (2) includes a fiber base material, a friction modifier, and an organic binder, includes the SiC fiber (2a) as the friction modifier, and the SiC fiber (2a) includes: 80% by volume or more is oriented at an angle of 40 ° to 140 ° with respect to the counterpart material (3),
The counterpart material (3) has a cermet layer (3a) on the surface thereof, and the friction material set (1). The friction material set (1) according to claim 1,
Friction material set (1) characterized in that 80% by volume or more of SiC fiber (2a) is oriented at 90 ° ± 5 ° with respect to counterpart material (3). The friction material set (1) according to claim 1 or 2,
The friction material set (1), wherein the fiber length of the SiC fiber (2a) is 0.5 mm to 20 mm. It is a friction material set (1) in any one of Claims 1-3,
The friction material (2) has 5 to 50% by volume of SiC fiber (2a), and the friction material set (1). The friction material set (1) according to any one of claims 1 to 4,
The friction material set (1), wherein the cermet layer (3a) of the counterpart material (3) contains tungsten carbide.

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