JPH04280865A - Carbon-metal composite material - Google Patents

Abstract

PURPOSE:To obtain a carbon-metal composite material for a sliding plate excellent in impact properties and sliding properties. CONSTITUTION:A raw molding material 6 containing one or both of metal fibers and a metal wire is charged in a space between an upper mold unit 3 and a lower mold unit 4, and another metal wire 9 orientated in one direction is inserted so that the metal wire may be arranged in a position on the non- sliding surface side. The raw molding material charged in the molds is subjected to pressure-and-heat molding at a prescribed temperature by using a press head 1 to obtain a molding containing the metal wire 9 arranged on the non- sliding surface side. The resultant carbon-metal composite material is excellent in impact resistance due to the metal wire or the metal net. Stabilized abrasion properties can be obtained since the metal wire or the metal net are arranged on the non-sliding surface side.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material that can be used primarily for railway pantograph sliding plates, and more particularly to a carbon-metal composite material that has excellent wear resistance, impact resistance, and electrical properties.

0002

[Prior Art] As a carbon material for sliding and current collection in electric vehicles, etc., in order to cope with the increase in speed of vehicles and the increase in power consumption due to air conditioning equipment, etc., the excellent sliding properties of carbon and the electrical conductivity of metal are used. Carbon/metal composite sliding plates that take advantage of their properties 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 Patent Application Laid-open No. 62-72564); ■ Manufactured by a method in which metal fibers are oriented in one direction and blended into raw materials for carbon materials, then molded and fired. Composite materials (JP-A-62-197
352).

[0003] However, the above mentioned carbon/metal sliding plates are in the transition period from the current metal sintered sliding plates to carbon/metal based sliding plates, that is, metal sintered and carbon/metal based sliding plates. The drawback is that the sliding plates are subject to large wear when sliding on a rough trolley wire (made of copper), which is intended for mixed use of the sliding plates. In order to eliminate such drawbacks, the present inventor has developed the following methods: (1) Mixing metal fibers and metal powder into a carbon material raw material whose main components are carbon aggregate powder and binder pitch, molding this raw material under pressure and heat, and then sintering it. We previously proposed a method for obtaining a carbon-metal composite material with excellent wear resistance by
.

By the way, when the sliding plate is used, the sliding plate may hit violently 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 be damaged 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 above-mentioned carbon-metal composite materials have a common drawback of being significantly inferior in impact strength compared to conventional metal sintered sliding plates.

[0005] The reason for this poor impact strength is basically that the impact strength of carbon is low. In order to compensate for this, it is possible to increase the amount of metal components mixed or increase the length or thickness of the metal fibers, but if the metal components are increased or the size of the metal fibers is increased, An increase in the coefficient of friction with the trolley wire and an increase in the number of sparks generated between the trolley wire and the contact wire increases wear on the trolley wire and the sliding plate, which is undesirable.

[0006] In order to solve these problems, the present inventors added thin and short metal fibers with excellent friction properties to the sliding parts of the sliding plate, and added fibers with excellent impact resistance to the non-sliding parts. We previously proposed a carbon-metal composite material containing long and thick metal fibers (Japanese Patent Laid-Open No. 2-160665). However, even this composite material cannot be said to have sufficient impact resistance, and further improvement in impact strength is desired.

[0007]

[Problem to be Solved by the Invention] In view of the actual situation described above, the present invention is designed to prevent the sliding plate from being damaged even if the sliding plate is violently hit by ice or a detached trolley wire hoist. The present invention aims to provide a carbon-metal composite material that has excellent impact resistance and even better abrasion resistance.

[0008]

[Means for Solving the Problems] The present inventor has developed a carbon-metal composite material in which one or both of metal fibers and metal powder is blended into a carbon material raw material, and by blending a metal wire or a wire mesh therein, the impact resistance can be improved. We have discovered that it is possible to dramatically improve However, when metal wires or wire meshes appear on the sliding surface, stable friction characteristics cannot be obtained due to increased frictional resistance and sparks, and wear resistance deteriorates.

Based on this knowledge, the present invention is to arrange metal wires and wire meshes only in non-sliding parts in a carbon-metal composite material.
Or, the gist is to arrange a metal wire and/or wire mesh in a part of the thickness direction of a composite material containing metal powder, and to arrange this metal wire and/or wire mesh on the mounting surface side of the composite material. It is something to do.

0010

[Operation] Various carbon material raw materials in this invention include self-sintering mesophase powder, binary raw materials consisting of carbonaceous aggregate powder and pitch such as coke powder, and thermosetting resins such as phenolic resin. can be used. Here, 2
Examples of carbonaceous aggregates used as raw materials include coke powder made by carbonizing pitch, coal, etc. at about 1000℃ from the viewpoint of wear resistance, and isotropic carbon obtained by carbonizing phenolic resin. The higher the price, the better. 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 μm 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.

[0011] As the metal fiber, steel fiber,
Various metal fibers such as steel wool and copper fiber, and various metal powders can be used. Among these, steel fiber made from low carbon steel shows the best performance. The size of the metal fibers should be 0.5 mm in thickness considering the wear characteristics.
5 mm or less, preferably 0.1 mm or less, and the length is 10
A diameter of mm or less is suitable. The metal powder has a particle size of 100 mm from the viewpoint of obtaining a molded product with stable wear characteristics and high strength.
Preferably, the thickness is less than μm.

[0012] The impact resistance can be greatly improved by orienting the metal wires continuously in parallel to the longitudinal direction of the sliding plate and over the entire length of the sliding plate. The thickness of the metal wire is preferably 3 mmφ or less in consideration of the strength of the composite material. This is because when a metal wire with a large diameter is used, the adhesiveness between the carbonaceous matrix containing metal fibers and metal powder and the metal wire becomes weak, resulting in a decrease in strength. It is also preferable that the wire mesh is made of metal wire with a diameter of 3 mm.

[0013] The spacing between the metal wires and wire meshes in the composite material is not particularly limited, but it is preferably at least three times the diameter of the metal wires or wire meshes. This is because if the interval is narrow, the moldability of the composite material will deteriorate, and shear failure will easily occur at the interface between the carbon material and the metal wire or wire mesh.

[0014] Materials for the metal wire and wire mesh include steel, stainless steel, copper alloys such as copper, blue body, and brass casting, nickel, and nickel alloys, as well as carbides such as copper and nickel to prevent impact strength due to carburization. Steel plated with a metal that has a lower tendency to form than steel is preferable.

[0015] The metal wire or wire mesh is incorporated into the non-sliding portion of the carbon/metal composite sliding material. In that case, it is also possible to blend these in multiple layers. In addition, adding metal wire or wire mesh to the sliding part will cause the amount of metal appearing on the sliding surface to vary, making the coefficient of friction unstable, making sparks more likely to occur during energized sliding, and affecting the friction properties. is undesirable because it becomes unstable.

[0016] The method of blending the metal wire and wire mesh into the matrix is not particularly limited, but after charging a certain amount of a mixture of metal fibers, metal powder, and carbonaceous raw materials into a mold, It can be easily blended by placing a metal wire or wire gauze, charging the same mixture onto it, and molding it.

[0017] As the molding method, various methods such as cold molding, pressurizing and heating molding, etc. can be employed. 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.
Because it is necessary to pressurize and heat the temperature range above ℃,
The maximum pressure heating temperature is 480℃ or higher, preferably 500℃
The above shall apply. The pressure of pressurized and heated molding is at least 40 kg/cm2 or more in a part of the range from room temperature to the maximum temperature of pressurized heating,
Preferably it is 80 kg/cm2 or more. This is because if the molding pressure is less than 40 kg/cm2, the bonding force between the binder and the metal decreases, making it impossible to obtain a carbon-metal composite material with good wear characteristics. The molded body obtained by the pressure and heat molding method is fired in the same manner as ordinary carbon materials.

[0018]

[Example] Figure 1 is a schematic diagram showing an example of a pressurized and heated molding device, where 1 is an upper press head and 2 is a 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 hot plate containing a sheathed heater 7-1, 8 is a heat insulating material, and 9 is a metal wire. FIG. 2 shows an example of a metal wire-containing molded body molded by the same pressurized and heated molding apparatus, in which (A) is a plan view, (B) is a front view, 10 is a sliding surface, and 11 is a non-sliding surface. It is a moving surface.

That is, after filling the molding raw material 6 between the upper mold 3 and the lower mold 4 and inserting the metal wire 9 into the raw material so as to be located on the non-sliding surface side, the seed Heater 7-
1 is energized to heat the hot plate 7, and pressurized by the press 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. As shown in FIG. 2, the obtained molded body has a metal wire 9 arranged on the non-sliding surface 11 side in parallel with the longitudinal direction of the molded body and over the entire length of the molded body.

[0020]

[Example 1] Next, a carbon-metal composite material manufactured by a pressure and heat molding method using the mold shown in FIG. 1 and a normal firing method will be described. As the aggregate for molding, regular grade petroleum coke was carbonized at 1000°C and had a diameter of 10 mm.
Coke powder with an average particle size of 15 μm was used, which was obtained by pulverizing it with a vibrating mill packed with stainless steel balls. The binder pitch was 440 mmHg of coal tar under a reduced pressure of 100 mmHg.
Coal tar pitch with a softening point of 240°C measured with a Koka type flow tester obtained by heat treatment at 60°C for 2 hours.
The material was ground to 0 mesh or less. As the metal additive, a low carbon steel fiber with a diameter of 0.05 mm and a length of 3 mm was used, and the amount added was 30% by volume.

[0021] The blended raw materials obtained by mixing these raw materials are
First, an amount that would have a thickness of 2.5 mm after molding was charged into a mold with internal dimensions of 100 mm width x 200 mm length. Next, on top of this, a steel wire with a wire diameter of 1.0 mm x length of 200 mm,
The length direction of the wires was made to match the longitudinal direction of the mold, and the wires were arranged at intervals of 5.0 mm. Thereafter, the raw materials were charged into the mold in an amount that would give a thickness of 7.5 mm after molding. The raw material charged into the mold in this way has a pressurizing capacity of 500
Pressure and heat molding using a ton hydraulic press (molding pressure 20
550℃ at a heating rate of 5℃/min under a pressure of 0Kg/cm2
The temperature was raised to 100 mm, maintained for 1 hour, and then cooled) to obtain a molded article with a width of 100 mm, a length of 200 mm, and a thickness of 10 mm. The obtained molded body was placed in a stainless steel container filled with coke powder, heated to 1000°C at a heating rate of 10°C/Hr in a nitrogen atmosphere, held for 4 hours, and then cooled and fired.

[0022] In addition, in the same manner as above, instead of the steel wire, a wire with a diameter of 1.0 mm and an interval between vertical lines and horizontal lines of 5 mm each was used.
100mm wide x 200mm long, made of steel wire mesh
A molded body with a thickness of 10 mm was obtained and fired under the same conditions as above.

[0023] Test pieces of width 10 mm x length 60 mm (thickness is the same as the thickness after firing) were prepared from the steel wire-containing carbon-metal composite material and the wire mesh-containing carbon-metal composite material obtained by the above method. was cut out and the Charpy impact value was measured. The cutting direction of the test piece was such that the direction of the length of 60 mm coincided with the direction of the length of the molded body of 200 mm. The Charpy impact value was measured so that the direction of impact was perpendicular to the pressing direction during molding. Table 1 shows the results.
Shown below.

[0024] Table 1 shows a comparative example in which pressure-heat molding and sintering were performed in the same manner as above, using only coke powder, binder pitch, and low carbon steel fibers as raw materials, without adding steel wire or wire mesh. The carbon obtained by
Charpy impact values of metal composites are also shown.

[0025] As is clear from Table 1, the impact strength of the product of the present invention containing unidirectionally oriented metal wire or wire mesh is dramatically improved compared to the composite material containing no such material.

[0026]

[Table 1]

[0027]

[Effects of the Invention] As explained above, the carbon-metal composite material according to the present invention has improved impact properties by incorporating metal wires or wire meshes oriented in one direction on the non-sliding surface side. In particular, it exhibits excellent properties as a sliding plate for pantographs, and its effects are enormous.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a pressure and heat molding apparatus for carrying out the method of the present invention.

FIG. 2 is a diagram showing an example of a metal wire-containing molded body molded by the same pressurized and heated molding device, in which (A) is a plan view and (B)
is a front view.

[Explanation of symbols]

1 Upper press head 2 Lower press head 3 Upper mold 4 Lower mold 5 Gold frame 6 Molding raw materials 7 Hot plate 8 Insulation material

Claims (2)

[Claims] [Claim 1] A composite material in which metal fibers and/or metal powder are blended with a carbon material raw material, further comprising a metal wire and/or wire mesh arranged in a part of the composite material in the thickness direction. carbon/metal composite material. 2. The carbon-metal composite material according to claim 1, wherein a metal wire and/or a wire mesh are arranged on the mounting surface side of the composite material.