KR20120057875A - Carbon-ceramic brake disc and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A carbon-ceramic brake disk and manufacturing method thereof are provided to maintain the function reinforcing a carbon-ceramic brake disk through keeping the initial shape of pan-based carbon fiber. CONSTITUTION: A carbon-ceramic brake disk manufacturing method is as follows. Pitch-based carbon fiber and phenol resin are mixed into a mixture(S11). The mixture is inserted a mold and pressed into a molded product(S12). The molded product is carbonized(S13). The carbonized molded product is worked mechanically(S14). Melted silicon is permeated into the worked molded product(S15). The worked molded product which permeated by melted silicon is polished(S16).

Description

CARBON-CERAMIC BRAKE DISC AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a carbon-ceramic brake disc.

Automobile brakes are divided into drum brakes and disc brakes.

Disc brakes slow or stop the rotation of the disc by the frictional force generated by the friction between the surface of the disc and the pad, thereby slowing down or stopping the vehicle.

Discs with good braking force should be light in weight, have high thermal shock resistance, high oxidation resistance, high wear resistance, high strength, and high coefficient of friction. To this end, in recent years, discs are made of carbon fiber reinforced ceramic composites.

Carbon fiber reinforced ceramic composites are materials in which the matrix is ceramic and reinforced with carbon fibers.

Hereinafter, a brake disc made of a carbon fiber reinforced ceramic composite will be referred to as a carbon-ceramic brake disc.

In general, a carbon-ceramic brake disc includes a step of mixing a phenol resin and carbon fibers to form a mixture, pressurizing and heating the mixture to form a molded body, carbonizing the molded body, and dissolving silicon in the carbonized molded body to infiltrate it. It is made through

As the carbon fiber, a fan (PAN, Polyacrylonitrile) -based carbon fiber is used. Fan-based carbon fiber has high strength, high toughness and low brittleness. Thus, it is suitable for use in reinforcing carbon-ceramic brake discs.

However, fan-based carbon fibers react well with silicon. Therefore, in the step of melting and infiltrating silicon into the carbonized molded body, the pan-based carbon fiber is easily eroded by silicon, and the eroded portion becomes silicon carbide (SiC).

1 is a view showing a state in which the fan-based carbon fiber is eroded by silicon, and the carbon of the eroded portion reacts with silicon to become silicon carbide.

As shown in FIG. 1, when the fan-based carbon fiber (Cf-pan) is eroded by silicon, it may be easily broken by an impact during brake operation. In this case, the function of reinforcing the carbon-ceramic brake disc cannot be properly performed.

Conventionally, in order to solve the problem that the fan-based carbon fiber is easily eroded by silicon, it was used by coating the fan-based carbon fiber. As a coating method, there is a method of forming a coating film around the pan-based carbon fibers by dipping the pan-based carbon fibers in a phenolic resin solution and then curing them. Due to the coating film, silicon does not easily erode the fan-based carbon fibers.

However, the above-described coating operation complicates the method of making the carbon-ceramic brake discs, which is expensive and time-consuming.

An object of the present invention is to provide a carbon-ceramic brake disc having excellent strength and a method of making the same without using a fan-based carbon fiber that requires coating.

A method of making a carbon-ceramic brake disc for achieving the above object comprises: a first step of mixing a pitch-based carbon fiber and a phenol resin to form a mixture; A second step of forming the molded body by pressing the mixture into a mold and pressing the mixture; A third step of carbonizing the molded body; A fourth step of machining the carbonized molded body; A fifth step of melting and infiltrating silicon into the machined molded body; And a sixth step of polishing the molded body in which the silicon has penetrated.

This object is also achieved by a carbon-ceramic brake disc in which pitch-based carbon fibers are randomly distributed.

In addition, the above object, a first step of making a first mixture by mixing the pitch-based carbon fibers and phenolic resin, a first step of making a second mixture by mixing the pitch-based carbon fibers and phenolic resin; A second step of forming a first molded body by putting the first mixture into a mold and pressing the mold with a press, and putting the second mixture into a mold and pressing the press with a press to form a second molded body; A third step of carbonizing the first molded body and carbonizing the second molded body; A fourth step of machining the carbonized first molded body and machining the carbonized second molded body; A fifth step of adhering the machined first molded body and the machined second molded body to each other; A sixth step of dissolving silicon in the first molded body and the second molded body bonded to each other; And a seventh step of polishing the first molded body and the second molded body in which the silicon has been penetrated.

In addition, the above object, a support layer; A friction layer bonded to upper and lower surfaces of the support layer, respectively; And an adhesive layer formed between the support layer and the friction layer, wherein each of the support layer and the friction layer is achieved by a carbon-ceramic brake disc in which pitch-based carbon fibers are randomly distributed.

The present invention uses a pitch-based carbon fiber having low reactivity with silicon to make a carbon-ceramic brake disc. For this reason, even after melt | dissolving and penetrating silicon in a carbonized molded object, a pitch type carbon fiber maintains the original shape as it is. Thus, the function of reinforcing the carbon-ceramic brake disc of the pitch-based carbon fiber is maintained as it is.

In addition, since the pitch-based carbon fiber can be used without coating, carbon-ceramic brake discs can be made simple, and cost and time can be saved.

In addition, by using pitch-based carbon fibers having superior thermal conductivity as compared to the fan-based carbon fibers, a carbon-ceramic brake disc having excellent thermal conductivity can be made.

1 is a view showing a state in which the fan-based carbon fiber is eroded by silicon, and the carbon of the eroded portion reacts with silicon to become silicon carbide.
Figure 2 is a flow chart illustrating a method of making a carbon-ceramic brake disc according to the first embodiment of the present invention.
FIG.3 (a), (b), (c) is a figure which shows the procedure which makes a molded object from a mixture.
4 shows a carbon-ceramic brake disc, made by a method of making a carbon-ceramic brake disc according to a first embodiment of the invention.
FIG. 5 is an enlarged view of portion A of FIG. 4.
6 is a flowchart illustrating a method of making a carbon-ceramic brake disc according to a second embodiment of the present invention.
7 (a), 7 (b) and 7 (c) are diagrams showing a procedure for forming a first molded body from the first mixture.
8 (a), 8 (b) and 8 (c) are diagrams showing a procedure of making a second molded product from the second mixture.
FIG. 9 is a view illustrating a carbon-ceramic brake disc made by a method of manufacturing a carbon-ceramic brake disc according to a second embodiment of the present invention.
FIG. 10 is an enlarged view of a portion A of FIG. 9.
FIG. 11 is an enlarged view of a portion B of FIG. 9.

Hereinafter, a method of making a carbon-ceramic brake disc according to the first embodiment of the present invention will be described.

Figure 2 is a flow chart illustrating a method of making a carbon-ceramic brake disc according to the first embodiment of the present invention. FIG.3 (a), (b), (c) is a figure which shows the procedure which makes a molded object from a mixture. The solid arrow shown in FIG. 3 indicates the moving direction of the press, and the dotted arrow indicates the direction in which the molded body is taken out of the mold.

As shown in Figures 2 and 3 (a), (b), (c), a method of making a carbon-ceramic brake disc according to a first embodiment of the present invention,

A first step (S11) of mixing a pitch-based carbon fiber and a phenol resin to form a mixture (X); A second step (S12) of putting the mixture (X) into a mold (M) and pressing the press (P) to form a molded body (Y); A third step S13 of carbonizing the molded body Y; A fourth step S14 of machining the carbonized molded body Y; A fifth step (S15) of melting and infiltrating silicon into the machined molded body (Y); And a sixth step S16 of grinding the molded body Y penetrated by the silicon.

Hereinafter, the first step S11 will be described.

30 to 70 vol% of the pitch-based carbon fibers and 70 to 30 vol% of the phenol resin are mixed to form a mixture (X).

Hereinafter, the second step S12 will be described.

As shown in FIG. 3 (a), the mixture X is placed in the mold M.

As shown in Fig. 3 (b), the mixture X is pressed by the press P to form the molded body Y. At this time, the pressure to pressurize is 3-5 MPa. Here, the mixture X can also be heated by the heater provided in the press P. The temperature to heat is 120-180 degreeC.

As shown in FIG.3 (c), the molded object Y is taken out from the mold M. As shown to FIG.

The molded body Y is composed of pitch-based carbon fibers randomly distributed in the cured phenolic resin.

Hereinafter, the third step S13 will be described.

The molded object (Y) is placed in a crucible. Put the crucible into the vacuum resistance furnace. It is either a vacuum atmosphere or an inert atmosphere in a vacuum resistance heating furnace.

In vacuum resistance heating, the temperature of the molded object Y is heated up to 1550 degreeC for 13 hours.

In vacuum resistance heating, the temperature of the molded object Y is kept at 1550 degreeC for 1-2 hours.

While the temperature of the molded body Y is raised and maintained at 1550 ° C., the organic compound contained in the molded body Y is thermally decomposed to become carbon. The organic compound is thermally decomposed and porosity is formed in the remaining position.

The fourth step S14 will be described below.

A shaft hole through which the axle passes is formed in the center of the molded body (Y).

Around the axial hole of the molded body (Y), a through hole through which a bolt coupled with a hat part passes, is drilled at equal intervals on the same circle. The hat part is combined with the wheels.

Hereinafter, a fifth step S15 will be described.

Put the silicon in the crucible.

Into the crucible is placed so that the lower part of the molded body (Y) is buried in silicon. Silicon is piled up on the molded body Y.

Put the crucible into the vacuum resistance furnace. It is either a vacuum atmosphere or an inert atmosphere in a vacuum resistance heating furnace.

In vacuum resistance heating, the temperature of the molded object Y is heated up to 1550 degreeC for 13 hours. In vacuum resistance heating, the temperature of the molded object Y is kept at 1550 degreeC for 1-2 hours.

While the temperature of the molded body Y is raised and maintained at 1550 ° C., the silicon melts and penetrates into the pores of the molded body Y.

Most of the silicon penetrated into the pores reacts with the carbon contained in the molded body (Y) to become silicon carbide (SiC). The remaining silicon that does not react with carbon fills the pores.

The sixth step S16 will be described below.

The molded object Y is polished with a grinder.

4 shows a carbon-ceramic brake disc, made by a method of making a carbon-ceramic brake disc according to a first embodiment of the invention.

As shown in Fig. 4, the carbon-ceramic brake disc 10 made by the method of making the carbon-ceramic brake disc according to the first embodiment of the present invention is composed of a single body.

The carbon-ceramic brake disc 10 has a shaft hole 11 through which an axle passes. Around the shaft hole 11, through-holes 12 through which bolts coupled with hat parts pass through are provided on the same circle at equal intervals.

The thickness of the carbon-ceramic brake disc 10 is 20-50 mm.

The composition of the carbon-ceramic brake disc 10 is 65-25 wt% of SiC, 15-25 wt% of Si, and 20-50 wt% of C.

FIG. 5 is an enlarged view of portion A of FIG. 4.

As shown in FIG. 5, the carbon-ceramic brake disc 10 has a short (1-3 mm) long pitch-based carbon fiber and a long (25-30 mm) pitch-based carbon fiber randomly distributed. The pitch-based carbon fiber is composed of a bundle of filament 1K to 48K having a diameter of 7 µm.

The reason that the long pitch carbon fibers and the short pitch carbon fibers are mixed is that when only the long pitch carbon fibers are distributed, the contact area between the pitch carbon fibers and the air increases and the pitch carbon fibers are oxidized. On the other hand, when only a short pitch-based carbon fiber is distributed, the reinforcing function of the pitch-based carbon fiber is reduced.

As shown in FIG. 5, the pitch-based carbon fiber has low reactivity with silicon, so that the surface is uneven and smooth. Therefore, the pitch-based carbon fiber can maintain the original shape even after silicon infiltration, and is not easily broken even when subjected to shock during brake operation.

6 is a flowchart illustrating a method of making a carbon-ceramic brake disc according to a second embodiment of the present invention. 7 (a), 7 (b) and 7 (c) are diagrams showing a procedure for forming a first molded body from the first mixture. 8 (a), 8 (b) and 8 (c) are diagrams showing a procedure of making a second molded product from the second mixture. The solid arrow shown in FIG. 7 or FIG. 8 shows the moving direction of the press, and the dotted arrow shows the direction in which the first molded body or the second molded body is taken out of the mold.

6, 7 (a), (b), (c), 8 (a), (b) and (c), the carbon-ceramic brake disc according to the second embodiment of the present invention How to make,

A first step (S21) of mixing a pitch-based carbon fiber and a phenol resin to make a first mixture (X1), and mixing a pitch-based carbon fiber and a phenol resin to form a second mixture (X2); The first mixture (X1) is put into the mold (M) and pressed with a press (P) to make a first molded body (Y1), the second mixture (X2) is put into a mold (M) and pressed with a press (P). A second step S22 of making a second molded body Y2; A third step (S23) of carbonizing the first molded body (Y1) and carbonizing the second molded body (Y2); A fourth step (S24) of machining the carbonized first molded body (Y1) and machining the carbonized second molded body (Y2); A fifth step (S25) of adhering the machined first molded body (Y1) and the machined second molded body (Y2) to each other; A sixth step (S26) of dissolving silicon in the first molded body (Y1) and the second molded body (Y2) adhered to each other; And a seventh step S27 of grinding the first molded body Y1 and the second molded body Y2 in which the silicon has penetrated.

Hereinafter, the first step S21 will be described.

30 to 70 vol% of pitch-based carbon fibers and 70 to 30 vol% of a phenol resin are mixed to form a first mixture (X1). A support layer to be described later is made of the first mixture X1.

30-70 vol% of pitch-based carbon fibers and 70-30 vol% of a phenol resin are mixed to form a second mixture (X2). A friction layer to be described later is made of the second mixture X2.

Hereinafter, the second step S22 will be described.

As shown in FIG. 7 (a), the first mixture X 1 is placed in the mold M.

The core body V is placed on the first mixture X1. The core body V has the shape of a cooling channel. The first mixture X1 is placed on the core body V.

As shown in FIG. 7B, the first molded body Y1 is formed by pressing the press P. As shown in FIG. At this time, the pressure to pressurize is 3-5 MPa. Here, the first mixture X1 may be heated by a heater provided in the press P. The temperature to heat is 120-180 degreeC.

As shown in FIG. 7C, the first molded object Y1 is taken out of the mold M. As shown in FIG.

The first molded product Y1 is composed of pitch-based carbon fibers randomly distributed in the cured phenolic resin.

As shown in FIG. 8A, the second mixture X2 is placed in the mold M. As shown in FIG.

As shown in FIG. 8B, the second mixture X2 is pressed by the press P to form the second molded body Y2. At this time, the pressure to pressurize is 3-5 MPa. Here, the second mixture X2 may be heated by a heater provided in the press P. The temperature to heat is 120-180 degreeC.

As shown in FIG. 8 (c), the second molded body Y2 is taken out of the mold M. As shown in FIG.

The second molded product Y2 is composed of pitch-based carbon fibers randomly distributed in the cured phenolic resin.

Hereinafter, the third step S23 will be described.

The first molded product Y1 is carbonized. The second molded product Y2 is carbonized. Since the method of carbonizing the first molded body Y1 and the second molded body Y2 is the same as the method of carbonizing the molded body in the first embodiment, the description thereof is omitted.

When carbonizing the first molded body Y1, the core body V is pyrolyzed. The amount of residual carbon upon thermal decomposition of the core body (V) is preferably less than 10 wt%. To this end, the core body (V) is made of a thermoplastic resin such as polycarbonate, ABS resin (Acrylonitrile Butadiene Styrene copolymer), styrene resin, polyethylene, acrylic resin and the like. When the core body V is thermally decomposed, the core body V is pyrolyzed and cooling channels are formed in the remaining empty space.

The fourth step S24 will be described below.

The axle passes through the shaft hole in the center of the first molded body (Y1) and the second molded body (Y2).

Through-holes through which bolts coupled with hat parts pass through the axial hole of the first molded body Y1 and the second molded body Y2 are drilled at equal intervals on the same circle. Hat parts are combined with wheels.

The fifth step S25 will be described below.

Liquid phenolic resin is applied to the upper and lower surfaces of the first molded body Y1. Coating thickness is 0.1 ~ 2mm. The second molded object Y2 is adhered to the upper and lower surfaces of the first molded object Y1. The phenolic resin in the liquid state exiting between the first molded object Y1 and the second molded object Y2 is removed.

Alternatively, a solid phenolic resin is sprinkled on the upper and lower surfaces of the first molded body Y1. The second molded body Y2 is placed on the upper and lower surfaces of the first molded body Y1, respectively, and is pressed by a press and heated by a heater installed in the press. As the phenolic resin in the solid state is melted, the second molded body Y2 is adhered to the upper and lower surfaces of the first molded object Y1. The phenol resin of the liquid state (the solid phenol resin melt | dissolved) which escaped between the 1st molded object Y1 and the 2nd molded object Y2 is removed.

When the first molded object Y1 and the second molded object Y2 are bonded together, an adhesive layer to be described later is formed between the first molded object Y1 and the second molded object Y2.

The sixth step S26 will be described below.

The silicon is melted and infiltrated into the first molded body Y1 and the second molded body Y2 adhered to each other. Since the method of dissolving silicon in the first molded product Y1 and the second molded product Y2 bonded to each other is the same as the method of infiltrating silicon into the molded product in the first embodiment, the description thereof is omitted.

The seventh step S27 will be described below.

The first molded object Y1 and the second molded object Y2 are polished by a grinder.

FIG. 9 is a view showing a carbon-ceramic brake disc made by a method of manufacturing a carbon-ceramic brake disc according to a second embodiment of the present invention, in which part of a friction layer and an adhesive layer are cut out so that a support layer is exposed. .

As shown in FIG. 9, the carbon-ceramic brake disc 100 produced by the method of manufacturing the carbon-ceramic brake disc according to the second embodiment of the present invention includes a support layer 110, a friction layer 120, and an adhesive layer ( 130).

The carbon-ceramic brake disc 100 has a shaft hole 101 through which the axle passes. Around the shaft hole 101, through-holes 102 through which bolts coupled with hat parts pass, are provided at the same interval on the same circle.

The support layer 110 has a cooling channel 111. The thickness of the support layer 110 is 20-50 mm. The composition of the support layer 110 is SiC 65-25 wt%, Si 15-25 wt%, C 20-50 wt%.

The thickness of the friction layer 120 is 0.1 ~ 2mm. The composition of the friction layer 120 is the same as the composition of the support layer 110, SiC 65-25 wt%, Si 15-25 wt%, C 20-50 wt%.

Since the composition of the support layer 110 and the composition of the friction layer 120 are the same, the coefficient of thermal expansion of the support layer 110 and the coefficient of thermal expansion of the friction layer 120 are the same. Therefore, in the process of making the carbon-ceramic brake disc 100, cracks do not occur in the friction layer 120 due to a difference between the thermal expansion coefficient of the support layer 110 and the thermal expansion coefficient of the friction layer 120.

The thickness of the adhesive layer 130 is 0.1-1 mm. The composition of the adhesive layer 130 is 50 wt% of SiC, 45 wt% of Si, and 5 wt% of C.

FIG. 10 is an enlarged view of a portion A of FIG. 9.

As illustrated in FIG. 10, pitch-based carbon fibers (Cf-pitch) are randomly distributed on the support layer 110. The pitch-based carbon fiber is composed of a bundle of filament 1K to 48K having a diameter of 7 µm. The length of pitch carbon fiber is 25-30 mm.

As shown in FIG. 10, the pitch-based carbon fiber included in the support layer 110 is low in reactivity with silicon, and thus the surface is uneven and smooth. Therefore, the pitch-based carbon fiber can maintain the original shape even after silicon infiltration, and is not easily broken even when subjected to shock during brake operation.

FIG. 11 is an enlarged view of a portion B of FIG. 9.

As illustrated in FIG. 11, pitch-based carbon fibers (Cf-Pitch) are randomly distributed in the friction layer 120. The pitch-based carbon fiber is composed of a bundle of filament 1K to 48K having a diameter of 7 µm. The length of pitch carbon fiber is 1-3 mm.

On the other hand, the pitch-based carbon fiber contained in the friction layer 120, the friction layer 120 is exposed to the outside, it is easy to oxidize with air. Therefore, in order to minimize the contact area with air, the pitch-based carbon fibers included in the friction layer 120 is shorter than the length of the pitch-based carbon fibers included in the support layer 110. Even if the length of the pitch-based carbon fiber is short, the strength of the friction layer 120 can be sufficiently maintained because the friction layer 120 is relatively less stressed than the support layer 110 during the brake operation.

As shown in FIG. 11, the pitch-based carbon fiber included in the friction layer 120 is low in reactivity with silicon, and thus the surface is uneven and smooth. Therefore, the pitch-based carbon fiber can maintain the original shape even after silicon infiltration, and is not easily broken even when subjected to shock during brake operation.

Claims (9)

A first step of mixing a pitch-based carbon fiber and a phenol resin to form a mixture;
A second step of forming the molded body by pressing the mixture into a mold and pressing the mixture;
A third step of carbonizing the molded body;
A fourth step of machining the carbonized molded body;
A fifth step of melting and infiltrating silicon into the machined molded body; And
And a sixth step of polishing the molded body in which the silicon is infiltrated. The method of claim 1, wherein the first step is a method of making a carbon-ceramic brake disc, wherein 30 to 70 vol% of the pitch-based carbon fibers and 70 to 30 vol% of the phenol resin are mixed to form a mixture. Carbon-ceramic brake discs with randomly distributed pitch-based carbon fibers. 4. The carbon-ceramic brake disc according to claim 3, wherein the pitch-based carbon fiber is composed of a long pitch-based carbon fiber (25-30 mm) and a short-length pitch-based carbon fiber (1-3 mm). A first step of making a first mixture by mixing pitch-based carbon fibers and phenol resins, and making a second mixture by mixing pitch-based carbon fibers and phenol resins;
A second step of forming a first molded body by putting the first mixture into a mold and pressing the mold with a press, and putting the second mixture into a mold and pressing the press with a press to form a second molded body;
A third step of carbonizing the first molded body and carbonizing the second molded body;
A fourth step of machining the carbonized first molded body and machining the carbonized second molded body;
A fifth step of adhering the machined first molded body and the machined second molded body to each other;
A sixth step of dissolving silicon in the first molded body and the second molded body bonded to each other; And
And a seventh step of polishing the first molded body and the second molded body in which the silicon has penetrated. The method of claim 5, wherein the first step,
30-70 vol% of pitch-based carbon fibers and 70-30 vol% of phenol resin are mixed to form a first mixture,
A method of making a carbon-ceramic brake disc in which a second mixture is made by mixing 30 to 70 vol% of pitch-based carbon fibers and 70 to 30 vol% of a phenol resin. Support layer;
A friction layer bonded to upper and lower surfaces of the support layer, respectively; And
Consists of an adhesive layer formed between the support layer and the friction layer,
A carbon-ceramic brake disc having randomly distributed pitch-based carbon fibers in each of the support layer and the friction layer. The method of claim 7, wherein
The length of the pitch-based carbon fibers distributed in the support layer is 25 ~ 30mm,
A pitch-based carbon fiber distributed in the friction layer is a carbon-ceramic brake disc having a length of 1 ~ 3mm. The method of claim 7, wherein
The composition of the support layer and the friction layer, the carbon-ceramic brake disc is the same as SiC 65-25 wt%, Si 15-25 wt%, C 20-50 wt%.

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