JP2004225765A - Disc rotor for disc brakes for vehicles - Google Patents

Abstract

An object of the present invention is to provide a disk rotor of a vehicle disk brake having improved rigidity, heat resistance, heat dissipation, and wear resistance.
A disk rotor (1) of a vehicle disk brake (10) has at least a carbon nanofiber having an average diameter of 0.7 to 500 nm and an average length of 0.01 to 1000 μm and fullerene which is spherical shell carbon. It is formed by a metal containing one.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a disk rotor for a disk brake for a vehicle used for an automobile or the like.
[0002]
[Background Art]
2. Description of the Related Art A disc brake for a vehicle used in an automobile or the like is configured to brake a vehicle by obtaining a frictional force by pressing a brake pad attached to a caliper body against a disc rotor from both sides. 2. Description of the Related Art Conventionally, cast iron or chromium-based stainless steel is generally used as a disk rotor of a vehicle disk brake. However, there is a demand for improvements in brake characteristics such as heat resistance, heat dissipation, wear resistance, and weight reduction.
[0003]
Therefore, there has been proposed a disk rotor of a disk brake for a vehicle in which an oxide ceramic material is thermally sprayed on a sliding surface between the disk rotor and a brake pad to improve wear resistance. Further, the disc rotor of the disc brake for a vehicle has a base material made of aluminum to reduce the weight (see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2001-65612 (pages 1-5, FIGS. 1-3)
[0005]
[Problems to be solved by the invention]
However, the conventional light-weight disk rotor requires two steps, a step of manufacturing the disk rotor body and a step of spraying the disk rotor. Further, it is desired to further improve the rigidity, heat resistance, heat dissipation, and wear resistance of the reduced disk rotor.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a disk rotor for a disk brake for a vehicle, which is capable of improving rigidity, heat resistance, heat dissipation, and abrasion resistance and reducing the weight while maintaining the rigidity.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a disk rotor for a vehicle disk brake according to a first aspect of the present invention has a carbon nanofiber having an average diameter of 0.7 to 500 nm and an average length of 0.01 to 1000 μm. And a metal containing at least one of fullerene which is spherical shell carbon.
[0008]
According to the first aspect of the present invention, rigidity, in particular, fracture toughness can be improved by being formed of a metal containing at least one of carbon nanofiber and fullerene, and a disk rotor can be obtained while maintaining rigidity. The weight can be reduced. Further, according to this aspect, heat resistance, heat dissipation, and abrasion resistance can be improved. In particular, since the friction coefficient does not easily decrease at high temperatures (heat resistance) and the amount of wear is small (abrasion resistance), the braking effect at the time of braking from a high rotation region or at a high load region is improved.
[0009]
Here, in the disk rotor of the vehicle disk brake according to the first aspect of the present invention,
The metal can be aluminum or an aluminum alloy.
[0010]
With this configuration, the weight of the disk rotor can be reduced while maintaining the rigidity. As a result, it is possible to contribute to reducing the weight of a vehicle, especially a vehicle for competition. Further, by containing at least one of carbon nanofiber and fullerene in aluminum or an aluminum alloy which is more likely to be worn than cast iron or stainless steel, wear resistance can be improved.
[0011]
Here, in the disk rotor of the vehicle disk brake according to the first aspect of the present invention,
The metal can be magnesium or a magnesium alloy.
[0012]
With this configuration, the weight of the disk rotor can be reduced while maintaining the rigidity. As a result, it is possible to contribute to reducing the weight of a vehicle, especially a vehicle for competition. Further, wear resistance can be improved by containing at least one of carbon nanofiber and fullerene in magnesium or a magnesium alloy which is more likely to be worn than cast iron or stainless steel.
[0013]
Here, in the disk rotor of the vehicle disk brake according to the first aspect of the present invention,
The metal can be titanium or a titanium alloy.
[0014]
With this configuration, the weight of the disk rotor can be reduced while maintaining the rigidity. As a result, it is possible to contribute to reducing the weight of a vehicle, especially a vehicle for competition.
[0015]
Here, in the disk rotor of the vehicle disk brake according to the first aspect of the present invention,
The carbon nanofiber may be subjected to an ion implantation process.
[0016]
By adopting such a configuration, the ion-implanted carbon nanofiber has at least a surface chemical composition that is changed, and the metal (aluminum, magnesium, titanium, etc.) constituting the disk rotor and the carbon nanofiber are formed. Adhesiveness and wettability are improved, the mechanical strength of the disk rotor can be further improved, and the dispersibility of the carbon nanofibers in the metal is improved, so that uniform performance can be obtained as a whole.
[0017]
Here, in the disk rotor of the vehicle disk brake according to the first aspect of the present invention,
The carbon nanofiber may be subjected to a sputter etching process.
[0018]
With such a configuration, the carbon nanofibers subjected to the sputter etching process have fine irregularities formed on the surface thereof. Therefore, the metal (aluminum, magnesium, titanium, etc.) constituting the disk rotor and the carbon nanofibers are formed. Adhesiveness and wettability are improved, the mechanical strength of the disk rotor can be further improved, and the dispersibility of the carbon nanofibers in the metal is improved, so that uniform performance can be obtained as a whole.
[0019]
Here, in the disk rotor of the vehicle disk brake according to the first aspect of the present invention,
The carbon nanofiber can be plasma-treated.
[0020]
With such a configuration, the carbon nanofibers subjected to the plasma treatment are subjected to surface modification such as formation of fine irregularities on the surface thereof. Therefore, the metal (aluminum, magnesium, titanium, etc.) constituting the disk rotor is formed. In addition to improving the adhesiveness and wetting of carbon nanofibers, the mechanical strength of the disk rotor can be further improved, and the dispersibility of carbon nanofibers in metal improves, resulting in uniform performance throughout. Can have.
[0021]
Here, in the disk rotor of the vehicle disk brake according to the first aspect of the present invention,
The fullerene includes carbon 60 and carbon 70,
The carbon 60 may be contained more than the carbon 70.
[0022]
With such a configuration, in the process of synthesizing fullerene, carbon 60 synthesized more than carbon 70 can be effectively used. Since fullerene has high dispersibility in metal, uniform characteristics can be obtained in the entire disk rotor.
[0023]
Here, in the disk rotor of the vehicle disk brake according to the first aspect of the present invention,
The metal may contain carbon and a carbon compound obtained in a synthesis process of at least one of the carbon nanofiber and the fullerene.
[0024]
With such a configuration, carbon and carbon compounds, which are impurities synthesized, can be effectively used in the process of synthesizing carbon nanofibers and / or fullerenes.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0026]
FIG. 1 is a diagram illustrating a disk rotor 1 of a vehicle disk brake 10 according to one embodiment of the present invention. FIG. 2 is a sectional view of the disc brake 10. FIG. 3 is a schematic configuration diagram of an omnidirectional ion implantation apparatus, and FIG. 4 is a partial cross-sectional view showing another embodiment of the turntable.
[0027]
As shown in FIG. 2, the structure of the disc brake 10 used in a vehicle such as an automobile is transmitted to the hydraulic chamber 14 of the caliper body 11 by hydraulic pressure of a hydraulic device and presses the piston 12. The friction material of the pad 20 is pressed against the disk-shaped disk rotor 1, and the kinetic energy of the vehicle is changed into thermal energy by the frictional action to perform braking.
[0028]
As shown in FIG. 1, a disk rotor 1 of a vehicle disk brake 10 has a smooth sliding surface 4 against which a pad 20 is pressed, formed on both outer peripheral surfaces of a disk-shaped main body 2. In the present embodiment, the main body 2 of the disk rotor 1 is made of aluminum for ease of manufacture and the like, but may be made of cast iron or stainless steel as long as it is made of metal. Therefore, it can be appropriately selected from so-called light metals such as aluminum, aluminum alloy, magnesium, magnesium alloy, titanium, and titanium alloy.
[0029]
The method for forming the disk rotor 1 of the present invention is not particularly limited, but can be manufactured by forging, casting, powder metallurgy, metal injection molding (MIM), or the like. In the present embodiment, at least one of carbon nanofiber and fullerene is mixed into a molten metal (aluminum molten metal), and a cavity formed by a mold is filled with the molten metal (aluminum molten metal) and pressurized. After the molten metal is solidified, the main body 2 of the disk rotor 1 is taken out of the cavity and subjected to a desired cutting process to obtain a disk rotor 1 as a final product. In addition, a slit, a hole, or the like may be appropriately formed on the sliding surface 4 of the disk rotor 1 by this cutting.
[0030]
Preferably, the disk rotor 1 contains 0.01 to 50% by weight of carbon fiber and fullerene in total. If the proportion of carbon fiber and fullerene exceeds 50% by weight, it is not preferable in terms of moldability, and if it is less than 0.01% by weight, mechanical strength may not be sufficiently improved. When the carbon fiber and the fullerene are each independently contained, the above weight ratio is the weight percentage of the carbon fiber and the fullerene alone.
[0031]
The carbon nanofiber to be mixed with a metal such as aluminum is preferably a carbon nanofiber having an average diameter of 0.7 nm to 500 nm and an average length of 0.01 to 1000 μm. The amount of the carbon nanofiber is 0.01 to 50% by weight in the metal of the main body 2 of the disk rotor 1, for example, aluminum, from the viewpoint of the fluidity during molding and the strength of the obtained disk rotor. It is preferred that Such a carbon nanofiber is a so-called carbon nanotube having a single-layer structure in which a graphene sheet having a carbon hexagonal mesh surface is closed in a cylindrical shape or a multilayer structure in which these cylindrical structures are nested. The carbon nanotube may be composed of only a single-layer structure or only a multi-layer structure, and may be a mixture of a single-layer structure and a multi-layer structure. Further, a carbon material partially having a carbon nanotube structure can also be used. In addition, it may be called by a name such as graphite fibril nanotube other than the name carbon nanotube.
[0032]
The single-walled carbon nanotube or the multi-walled carbon nanotube is manufactured to a desired size by an arc discharge method, a laser ablation method, a vapor phase growth method, or the like.
[0033]
The arc discharge method is to obtain multi-walled carbon nanotubes deposited on a cathode by performing arc discharge between electrode materials made of carbon rods in an atmosphere of argon or hydrogen at a pressure slightly lower than atmospheric pressure. Further, the single-walled carbon nanotube is obtained by mixing a catalyst such as nickel / cobalt into the carbon rod, performing arc discharge, and soot adhering to the inner surface of the processing container.
[0034]
In the laser ablation method, a carbon surface mixed with a catalyst such as nickel / cobalt as a target is irradiated with a strong pulsed laser beam of a YAG laser in a rare gas (eg, argon) to melt and evaporate the carbon surface. This is to obtain a single-walled carbon nanotube.
[0035]
The vapor phase growth method is a method in which hydrocarbons such as benzene and toluene are thermally decomposed in a gas phase to synthesize carbon nanotubes, and examples thereof include a fluidized catalyst method and a zeolite supported catalyst method.
[0036]
Before the carbon nanofiber is mixed with a metal such as aluminum, a surface treatment such as an ion implantation treatment, a sputter etching treatment, and a plasma treatment can be performed in advance to improve the adhesiveness and wettability with aluminum.
[0037]
(Ion implantation processing)
Ion implantation is a process in which necessary energy is given to an element ionized by an ion source, such as oxygen, by an accelerator, and ions are implanted in the surface of a carbon nanofiber in a vacuum chamber maintained in a high vacuum state by a vacuum pump. It is something to drive.
[0038]
The ion implantation processing according to one embodiment of the present invention will be described with reference to the schematic configuration diagram of the omnidirectional ion implantation apparatus shown in FIG. In the omnidirectional ion implantation apparatus 50, a rotary table 53 for placing a sample (for example, carbon nanofiber 52) to be subjected to an ion implantation process is rotatably arranged in a vacuum chamber 51 made of, for example, stainless steel connected to a vacuum pump 57. I have. The turntable 53 is connected to a pulse bias power supply 54, and is insulated from the vacuum chamber 51 by an insulator 55. The vacuum chamber 51 is connected to a process gas supply device 58, a coil 60 connected to a high frequency power supply 59, an arc evaporation source 61, and an infrared radiation thermometer 62 for measuring the temperature inside the vacuum chamber 51.
[0039]
In the ion implantation process, a gas is supplied from a process gas supply device 58 into a vacuum chamber 51 which is brought into an appropriate vacuum state by a vacuum pump 57, and a plasma is generated around a coil 60 by a high frequency power supply 59. The gas ionized thereby is drawn into a sample, for example, the carbon nanofiber 52 connected to the negative electrode of the pulse bias power supply 54 and injected. Further, metal ions can be injected into the sample, for example, the carbon nanofibers 52 by the arc evaporation source 61 connected to the vacuum chamber 51. In this case, the metal evaporation source in the arc evaporation source 61 is connected to a DC arc power supply (not shown), and is evaporated by arc discharge. At this time, since the rotating table 53 and the sample, for example, the carbon nanofibers 52 are applied by the negative DC bias power source 56 switched by the switch 63, the metal ions are injected into the sample, for example, the carbon nanofibers 52.
[0040]
Further, the rotary table 53 of the omnidirectional ion implanter 50 may have a structure having a stirring blade 53a and a container 53b as shown in FIG. The container 53b has a wide opening at the top, and a sample such as the carbon nanofiber 52 can be arranged in the container 53b. During the ion implantation process, the powder sample such as the carbon nanofibers 52 can be uniformly and entirely subjected to the ion implantation process by being stirred by the rotation of the stirring blades 53a. The rotation speed of the stirring blade 53a can be appropriately adjusted depending on the amount of the carbon nanofibers 52, the ion implantation processing time, and the like.
[0041]
The surface of the ion-implanted carbon nanofiber is chemically modified, the wettability and adhesion of the body 2 of the disk rotor 1 to metal such as aluminum are improved, and the fracture toughness and wear resistance of the disk rotor 1 are improved. The property can be improved.
[0042]
Elements used for the ion implantation treatment include, for example, oxygen (O), nitrogen (N), chlorine (Cl), chromium (Cr), carbon (C), boron (B), titanium (Ti), and molybdenum (Mo). , Phosphorus (P), aluminum (Al), etc., can be appropriately selected depending on the compatibility with the metal of the main body 2 of the disk rotor 1, for example, aluminum.
[0043]
(Sputter etching treatment)
In the dry etching sputter etching process, glow discharge is performed by applying an alternating current in an etching gas or an ultra-low pressure inert gas atmosphere such as argon (Ar) in a vacuum chamber maintained in a high vacuum state by a vacuum pump. In addition, etching is performed by colliding ions with the surface of the carbon nanofiber in contact with the electrode exposed in the plasma generated by the glow discharge.
[0044]
The surface of the carbon nanofiber that has been subjected to the sputter etching treatment is physically etched to form fine (nano-sized) irregularities. The unevenness of the surface of the carbon nanofibers increases the contact area of the main body 2 of the disk rotor 1 with metal, for example, aluminum, so that the adhesive strength between aluminum and the carbon nanofibers can be improved. It is possible to improve the fracture toughness and wear resistance of the disk rotor 1 manufactured by mixing carbon nanofibers with aluminum.
[0045]
(Plasma treatment)
The plasma treatment modifies the surface by irradiating the carbon nanofibers with plasma. As the plasma processing, general glow discharge processing, corona discharge processing, or the like can be employed.
[0046]
For example, a plasma applies a high-voltage / high-frequency pulse voltage generated by a pulse generation circuit between a discharge electrode and a counter electrode facing each other, causing a corona discharge between the two electrodes and causing a plasma in the air. Is caused to occur. The object to be processed is arranged in a stationary state or a moving state between the two electrodes, and its surface is subjected to plasma processing.
[0047]
The method of plasma generation is a bipolar discharge type in which a voltage of several hundred to several thousand volts is applied to two parallel flat electrodes to discharge them. A large amount of electrons emitted from a hot cathode collide with gas molecules before entering the anode. Thermionic discharge type that generates plasma, magnetron discharge type that discharges in a high vacuum using a magnetic field, electrodeless discharge type that generates plasma by high-frequency electromagnetic induction, ECR that sends microwaves to a resonance chamber with a magnetic field to resonate electrons (Electron Cyclotron Resonance) discharge type and the like can be selected as appropriate.
[0048]
The surface of the carbon nanofibers thus plasma-treated has improved adhesion and wettability with the metal of the main body 2 of the disk rotor 1 such as aluminum, and the surface of the disk rotor 1 manufactured by mixing carbon nanofibers into aluminum. Improved fracture toughness and wear resistance can be obtained.
[0049]
The fullerene used in the present embodiment includes spherical shell carbon such as fullerenes such as carbon 60 (hereinafter referred to as C60), C70, C74, C76, C78, C82, C84, C720, and C860. Is preferably a main component. Further, it is preferable to use fullerene containing C60 as a main component and containing C70 in a smaller amount than C60. Further, C60 may be the main component, and may include other fullerenes, or may include other carbon and carbon compounds simultaneously generated when fullerene other than fullerene is generated. The form of the fullerenes may be, for example, a soccer ball shape, a bucky ball shape, or the like.
[0050]
Further, the fullerenes may be modified by introducing a substituent or the like. The modification method is not particularly limited, and for example, a 5-membered carbon ring portion of a fullerene having high reactivity can be chemically modified. The type of the substituent is not particularly limited, and examples thereof include an alkyl group, an aryl group, an aralkyl group, a dioxolane unit, a halogen or an oxygen atom, and the like, and the modification may be performed by introducing a liquid crystal polymer, a dye, polyethylene oxide, or the like. Good. Modification of fullerenes allows for improved affinity with selected metals, such as aluminum, and dispersion of fullerenes.
[0051]
C60 fullerene was subjected to arc discharge in a helium atmosphere using a graphite electrode, the resulting soot was extracted with benzene, and the resulting C60 mixture was purified by column separation using basic activated alumina as a carrier and hexane as a developing solvent. Prepared. The method for obtaining fullerene is not limited to the arc discharge method, but may be another method.
[0052]
As described above, the heat resistance and the wear resistance of the disk rotor 1 manufactured by mixing fullerene into the metal, for example, aluminum of the main body 2 of the disk rotor 1 can be improved.
[0053]
It should be noted that the present invention is not limited to the present embodiment, and can be modified into various forms within the scope of the present invention.
[0054]
For example, a composite material obtained by mixing magnesium or a magnesium alloy with aluminum or an aluminum alloy constituting the main body 2 of the disk rotor 1 by several percent, such as a metal mainly containing aluminum, magnesium, and titanium, and another metal May be mixed.
[Brief description of the drawings]
FIG. 1 is a front view of a disk rotor of a vehicle disk brake according to one embodiment of the present invention.
FIG. 2 is a sectional view of a disc brake according to one embodiment of the present invention.
FIG. 3 is a schematic explanatory view of an omnidirectional ion implantation apparatus used in one embodiment of the present invention.
FIG. 4 is a partial sectional view showing another embodiment of the rotary table of the omnidirectional ion implantation apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Disc rotor 2 Main body 4 Sliding surface 10 Disc brake 11 Caliper body 12 Piston 14 Hydraulic chamber 50 Omnidirectional ion implanter 53 Rotary table 53a Stirrer blade 53b Container

Claims (9)

In a disk rotor of a vehicle disk brake,
A disc brake for a vehicle, which is formed of a metal containing at least one of carbon nanofiber having an average diameter of 0.7 to 500 nm and an average length of 0.01 to 1000 μm and fullerene which is a spherical shell carbon. Disk rotor. The disk rotor for a vehicle disk brake according to claim 1,
The disc rotor for a disc brake for a vehicle, wherein the metal is aluminum or an aluminum alloy. The disk rotor for a vehicle disk brake according to claim 1,
The disc rotor for a disc brake for a vehicle, wherein the metal is magnesium or a magnesium alloy. The disk rotor for a vehicle disk brake according to claim 1,
The disc rotor for a disc brake for a vehicle, wherein the metal is titanium or a titanium alloy. The disk rotor for a vehicle disk brake according to any one of claims 1 to 4,
A disk rotor for a disk brake for a vehicle, wherein the carbon nanofibers are subjected to ion implantation. The disk rotor for a vehicle disk brake according to any one of claims 1 to 4,
A disk rotor for a disk brake for a vehicle, wherein the carbon nanofibers are sputter-etched. The disk rotor for a vehicle disk brake according to any one of claims 1 to 4,
A disk rotor for a disk brake for a vehicle, wherein the carbon nanofibers are plasma-treated. The disk rotor for a vehicle disk brake according to any one of claims 1 to 7,
The fullerene includes carbon 60 and carbon 70,
A disc rotor for a vehicle disc brake, wherein the disc rotor contains more carbon 60 than carbon 70. The disk rotor for a vehicle disk brake according to any one of claims 1 to 8,
The disc rotor for a disc brake for a vehicle, wherein the metal contains carbon and a carbon compound obtained in a synthesis process of at least one of the carbon nanofiber and the fullerene.

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