JPH02160662A - Carbon-metal composite material - Google Patents

Abstract

PURPOSE:To obtain the title composite material excellent in resistance to wear and impact and electrical properties, etc., thus suitable for pantograph sliding plates by incorporating a carbonaceous raw material with metallic fiber so as to develop domains differing in said metallic fiber content from one another. CONSTITUTION:Metallic fiber (e. g. steel fiber) is incorporated in a carbonaceous raw material such as solf-sinterable mesophase powder, coke powder plus pitch, or phenolic resin so as to develop domains differing in said metallic fiber content from one another. For example, as for a pantograph sliding plate for railroad, the upper part sliding with trolley lines is made lower in said content so as to improve the frictional and/or sparking characteristics, while the lower part not sliding with the trolley lines is made higher in said content to improve the impact strength. To produce the objective composite material, several kinds of mixed material differing in metallic fiber content from one another are successively charged into a mold followed by forming and baking.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a composite material that can be used mainly for pantograph sliding plates for railways. Concerning carbon-metal composite materials with special characteristics.

Conventional technology Carbon materials for sliding and current collection in electric vehicles, etc., are based on the excellent sliding properties of carbon and the electrical conductivity of metals, in order to cope with the increasing speed of vehicles and the increase in power consumption due to air conditioning equipment, etc. Carbon/metal composite) W plates are being adopted.

This type of carbon-metal composite material includes, for example: ■ Composite material manufactured by pressurizing and impregnating the pores of a carbon material with a specific metal; Composite material manufactured by a method in which carbonization is performed after molding using a molding method (Japanese Unexamined Patent Application Publication No. 62-72564), ■ Manufactured by a method in which metal fibers are oriented in one direction and blended into raw materials for carbon materials, and then molded and fired. Composite materials (JP-A-62-197
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However, the carbon/metal based sliding plates mentioned above are in the transition period from the current sintered metal based sliding plates to the carbon/metal based sliding plates, that is, the transition between the metal sintered and carbon/metal based sliding plates. The drawback is that the sliding plate is subject to a large amount of wear when the trolley wire (made of copper) is slid in a rough condition, which is intended for mixed use.

In order to eliminate such drawbacks, the present inventors have developed a carbon material raw material whose main components are carbon material aggregate powder and binder pitch.
We previously proposed a method to obtain a carbon-metal composite material with excellent wear resistance by blending metal fibers and metal powder, molding this raw material under pressure and heating, and then firing it (Japanese Patent Application No. 63-26).
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By the way, when using a sliding board, the sliding board may hit hard against a trolley wire hanger that has come off due to ice forming on the trolley wire or for some other reason.

At that time, if the impact strength of the sliding plate is low, the sliding plate will break and its fragments will be scattered around, which is extremely dangerous.

Therefore, the sliding plate is required to have not only wear resistance but also impact resistance.

However, the carbon-metal composite materials described above have a common drawback of being significantly inferior in impact strength compared to conventional metal sintered sliding plates.

The reason for this poor impact strength is basically that the impact strength of carbon is low. Therefore, impact strength can be improved by increasing the amount of metal components blended to compensate for this, but as the amount of metal components increases, more sparks will be generated between the contact wire and the contact wire, resulting in greater wear on the contact wire and sliding plate. Undesirable.

Problems to be Solved by the Invention In view of the actual situation described above, the present invention has been designed to prevent damage to the sliding plate even if the sliding plate hits hard against ice or a detached trolley wire hoist. The present invention aims to provide a carbon-metal composite material that has excellent impact resistance, roughly stable spark characteristics, and good wear resistance.

Means for Solving the Problems The inventor has developed a carbon-metal composite material that has both wear resistance and impact resistance without increasing the content of metal fibers in a composite material that combines metal fibers with carbon material raw materials. As a result of various studies on composite materials, we found that it is possible to have wear resistance, impact resistance, and spark properties with the same amount by creating parts with a lot of metal fibers and parts with a small amount of metal fibers in the molded product. I found it.

In other words, taking a sliding plate as an example, the part that slides on the trolley wire (the upper part) has a low content of metal fibers to improve wear and spark characteristics, while the part that does not slide on the trolley wire (the upper part) The lower part) has excellent abrasion resistance and impact resistance as a whole by increasing the content of metal fibers,
Moreover, a carbon-metal composite material with good spark characteristics can be obtained.

That is, the gist of the present invention is a carbon-metal composite material in which the content of metal fibers is partially varied in a composite material in which metal fibers are blended with a carbon material raw material.

Function As the carbon material raw material in this invention, there are various types such as self-sintering mesophase powder, binary raw material consisting of carbonaceous aggregate powder and pitch such as coke powder, and thermosetting resin such as phenolic resin. Things can be used.

Here, as the carbonaceous aggregate in the binary raw material, materials with high hardness such as coke powder obtained by carbonizing pitch, coal, etc. at about 100°C, and isotropic carbon obtained by carbonizing phenolic resin are used. is preferred.

Regarding the particle size of the carbonaceous aggregate, from the viewpoint of strength and wear resistance, a small particle size is preferable, and it is preferable to use the carbonaceous aggregate by pulverizing it to 20 Atm or less.

Binder pitches include coal tar medium pitch,
A high softening point pitch obtained by further heat-treating this or the like can be used.

The pitch is preferably one that exhibits fluidity when heated and has as low a volatile content as possible, since this improves the strength and abrasion resistance of the composite material.

Metal fibers have a larger aspect ratio and a greater reinforcing effect than metal particles or impregnated metals, so when compared with the same blending amount, the effect of improving the static strength and impact strength of the composite material is large.

Various metal fibers such as steel fiber, steel wool, copper fiber, etc. can be used as the metal fiber. Among these, steel fiber made from low carbon steel shows the best performance.

The shape, size, etc. of the metal fibers are not particularly limited, but from the viewpoint of obtaining a molded product with high strength, those having a thickness of 0.5 mm or less and a length of 1 mm or more are preferable.

Taking a sliding plate as an example, the content of the metal fibers is set high in the portion corresponding to the wear allowance, and low in the portion other than the wear allowance. In this case, the quantitative ratio is preferably 10 to 40% by volume for the portion corresponding to the wear allowance, and 40 to 65% by volume for the portion other than the wear allowance. In addition to metal fibers,
It is also possible to add some metal powder.

Such a carbon/metal fiber composite material is obtained by sequentially charging a plurality of mixed raw materials with different metal fiber contents into a mold, followed by molding and firing.

As the molding method, various methods such as cold molding, extrusion molding, pressurized heating molding, etc. can be adopted. Among these, the method of using pitch as a binder and pressurizing and heating molding yields a carbon-metal composite material with the best strength and wear resistance.

The pressure and heat molding conditions are in the temperature range where the binder pitch solidifies, that is, 480°C or higher, preferably 500°C.
Since it is necessary to pressurize and heat in the above temperature range, the maximum pressure and heating temperature is 480°C or higher, preferably 500°C or higher.

The pressure of pressurized and heated molding is at least 40 kg-J or more in a part of the range from normal temperature to the maximum temperature of pressurized heating, preferably 80 K.
qJ or more. This is because if the molding pressure is less than 4014, the bonding force between the binder and the metal decreases, and a carbon-metal composite material having good wear characteristics cannot be produced.

The molded body obtained by the pressure and heat molding method is fired in the same manner as ordinary carbon materials.

Example Figure 1 is a schematic diagram showing an example of a pressurized and heated mold.
1) is the upper press head, (2) is the lower press head (fixed), (3) is the upper mold, (4) is the lower mold, (5) is the metal frame, (6) is the molding raw material, (7 ) is a sheathed heater (7-1
) hot plate, (8) is covered with heat insulating material.

That is, after filling the molding raw material (6) between the upper mold (3) and the lower mold (4), the sheath heater (7-1) is energized to heat the hot plate (7), and the press Pressure is applied by head (1). The mold may be preheated.

The molded body obtained by such a pressure-heat molding method can be fired in a non-oxidizing atmosphere at a temperature below the melting point of the metal fiber.

Next, a carbon-metal composite material manufactured by a pressure and heat molding method using a mold shown in FIG. 1 and a normal firing method will be described.

As the molding aggregate, coke powder with an average particle size of 12 particles obtained by carbonizing regular grade petroleum coke at 100°C and pulverizing it for 4 hours in a vibrating mill packed with stainless steel balls with a diameter of 10 m was used.

As the binder pitch, use 100mf of coal tar.
-It was heat treated at 420'C under reduced pressure for 6 hours and had a softening point of 250°C measured with a Koka type flow tester, which was pulverized to 60 mesh or less.

As the metal fiber, a low carbon steel fiber having a size of 0.05 sX O, 05#X and a length of 3 m was used.

In this example, four types of blended raw materials A to D obtained by mixing these three types of raw materials at the blending ratio shown in Table 1 were combined, and the lower part was placed in a mold with inner dimensions of 100 m width x 2 oos length. In order, the upper part was divided and charged in an amount that would have a thickness of 5#III after molding, and the fiber content of the upper and lower parts was varied, and then pressure and heat molding was performed using a hydraulic press with a pressure capacity of 500 tOn (
The molding pressure was 200, the temperature was raised to 550°C at 5°C/min under the pressure of 4, held for 1 hour and then cooled), and the width was 100fiX the length was 2
A molded body of 00 InM x 10 #thickness was obtained.

The obtained molded body was placed in a stainless steel container filled with coke powder and heated at a heating rate of 12°C/Hr in a nitrogen atmosphere.
The temperature was raised to 000°C, held for 4 hours, and then cooled and fired.

From the obtained carbon-metal composite material, width 10# x length 60m
(The thickness is the same as the thickness after firing) was cut out, and the Charpy impact value and bending strength were measured.

The direction in which the test piece was cut out was such that the direction of length 60# coincided with the direction of length 200 m of the molded body.

The Charpy impact value was measured with the impact direction perpendicular to the pressing direction during molding.

The bending strength was measured with a bending span of 40 m by rolling down from the upper part during molding.

Next, from the same carbon-metal composite material, width 8#IX length 81
111+1X height approx. 10. Cut out a test piece so that the height direction matches the press direction during molding, use the surface that corresponds to the top surface during molding as the sliding surface, perform a wear test under the following conditions, and after the wear test The thickness change of the test piece was measured, and the wear volume per 1 learning distance of 100 was calculated.

Comparative Examples 6 and 7 had a large amount of wear and it was difficult to achieve both wear and impact strength, whereas the carbon-metal composites of the present invention in Tests FJb and 1 to 3, which were made of different raw materials on the upper and lower sides, had a large amount of wear. The material has excellent wear properties and Charpy impact strength.

Table 1 The Charpy impact value, bending strength, and wear amount are shown in Table 2.

For comparison, Table 2 also includes the physical properties of carbon-metal composites obtained by pressurizing, heating, molding, and firing using the same method as in the present invention using raw materials with the same fiber content on the top and bottom. Shown.

As is clear from Table 1, in the case of the comparative example made of the same raw materials for the upper and lower sides, the Charpy impact strength of test positive 4°5, which had a small amount of wear, was low, and as explained in detail in the margin of the invention below, the impact strength was The carbon-metal composite material according to the present invention not only has excellent wear resistance but also has excellent impact resistance, so it exhibits excellent properties especially as a sliding plate for pantographs.
The effect it brings is enormous.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a pressure-heat molding mold for carrying out the method of the present invention. 1... Upper press head 2... Lower press head 3... Upper mold 4... Lower mold 5...
Metal frame 6... Molding raw material 7... Hot plate
8... Insulation material agent Patent attorney Yoshihisa Oshida 1iJ

Claims (1)

[Claims] A carbon-metal composite material, which is a composite material in which metal fibers are blended into a carbon material raw material, and the content of the metal fibers is partially different.