JPH0699186B2 - Carbon / steel fiber composite material for pantograph sliding plate - Google Patents

Description

Description: TECHNICAL FIELD The present invention mainly relates to carbon for pantograph sliding plates, which has excellent strength characteristics and wear resistance suitable for pantograph sliding plates for railways.
Steel fiber composite material.

2. Description of the Related Art Carbon materials for sliding and collecting electricity in electric vehicles, etc. make use of the excellent sliding characteristics of carbon and the electrical conductivity of metals in order to respond to the speeding up of vehicles and the increase in power consumption due to cooling equipment. Carbon
Development of metal composites is desired.

Conventionally, as such a carbon-metal composite material, for example, a material in which pores of a carbon material are impregnated with a specific metal under pressure is known. Further, as a carbon / metal composite material having a performance superior to that of the carbon / metal composite material, a conventional charcoal, such as molding or extrusion molding, in which 2 to 30% by volume of metal fiber is blended, which is proposed by the present inventors, is used. A product manufactured by a method of molding after the material is molded and then carbonized (see JP-A-62-72564),
Alternatively, there is one produced by a method in which metal fibers are oriented in one direction and then molded (see JP-A-62-197352).

However, the sliding plate using these conventional carbon-metal composite materials has a lower bending strength than the conventional metal-based sliding plate even if the metal fibers are oriented in one direction to force the sliding plate. Met.

Therefore, these carbon-metal composite sliding plates are more likely to be lost or damaged when they collide with the frost attached to the overhead wire or to the trolley wire suspension tool that has come off due to an abnormal situation. There was a problem that reliability and safety were poor.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention improves the fact that a sliding plate using a carbon-metal composite material in which metal fibers are oriented in one direction is inferior in strength to a conventional metal-based sliding plate. It is an object of the present invention to provide a carbon / steel fiber composite material for a pantograph sliding plate, which has significantly better bending strength than the carbon / metal composite sliding plate.

Means for Solving the Problems As a result of examining the cause of the low bending strength of the carbon / steel fiber composite material, the present inventors have found the following.

The cause of the low bending strength of the carbon / steel fiber composite material is that during the carbonization of the composite material, the steel fiber is carburized by the carbon powder or pitch of the matrix to form metal carbide. It was found that the strength of the composite material decreases because the composition of steel fiber changes to a composition containing a large amount of iron carbide, cementite (Fe ₃ C).

In other words, the carburization reaction of steel fiber proceeds remarkably at 1000 ° C where the strength of carbon is sufficiently expressed,
The bending strength of the sliding plate is significantly reduced. Therefore, as a result of various studies on the method for suppressing the carburizing reaction of the steel fiber, the present inventors coated the surface of the steel fiber with a copper coating layer to suppress the carburizing reaction of the steel fiber at the time of carbonization and bend the composite material. It has been found that the strength and impact resistance can be significantly improved.

This invention was made on the basis of such findings, a steel material is oriented in one direction to a carbon material raw material, molded, carbonized composite material, the surface of the steel fiber is coated with copper. The gist is a carbon / steel fiber composite material for a pantograph sliding plate, which is characterized in that

Action The carbon material raw material in this invention is composed of self-sintering mesophase powder binder pitch and carbonaceous or graphitic aggregate 2
Various raw materials such as thermosetting resin such as phenol resin can be used.

Next, as the steel fibers, fibrous or wool-like ones manufactured by various methods such as thin plate cutting method, chatter vibration cutting method, wire cutting method and drawing method can be used. The material composition of the steel fiber is not particularly limited, and various materials such as ordinary steel, high-strength steel, and stainless steel can be used.

The reason why the steel fiber is oriented in one direction is as follows. That is, when the steel fiber is oriented in one direction, the electrical resistance is significantly reduced due to the improvement in the continuity of the steel fiber in the carbon material, and the steel fiber acts effectively as a reinforcing material due to the one-way orientation of the fiber. The impact resistance is remarkably improved, and in the bending strength test, it is possible to obtain a characteristic that the material bends without breaking even after passing the yield point. Therefore, carbon
In the case of a steel fiber composite material, it is effective to orient the steel fibers in one direction to improve strength and impact resistance.

As a method of orienting the steel fibers in the carbon material raw material in one direction, a method of orienting in one direction by a magnetic field of tens of thousands of gauss or more can be used when the steel fibers are ferromagnetic materials. When using a short fiber having a fiber length of about 5 mm, after charging a mixture of a short fiber metal and a raw material for a carbon material into a molding die through a slit having a width shorter than the length of the fiber, a method of molding, etc. Can be used.

Examples of the molding method include a cold uniaxial molding method, a pressure heating molding method, an extrusion molding method, and a CIP method. Among them, the carbon / steel fiber composite material having the best strength can be obtained by the method of using the pitch as the binder and performing the pressure heating molding.

Steel fiber can be plated and vaporized in various ways,
It is used by coating the surface with a copper coating layer, which is a material that is difficult to carburize. Even if the thickness of the surface coating layer is at most about 0.1 μm, it has a sufficient effect of suppressing the carburizing reaction. Although there is no particular upper limit to the thickness of the coating layer, a layer thickness of 1 μm or less is sufficient from the economical viewpoint.

Here, the material used for the steel fiber surface coating must be copper, since it is necessary for the pantograph slide plate to have excellent carburization resistance and low electrical resistivity. The reason is that, in the case of a pantograph sliding plate, if a material having a high electrical resistivity is used as the coating layer, the electrical conductivity of the steel fiber is not effectively expressed, and the electrical resistivity of the composite material is significantly increased, which is not preferable. .

The shape, size and the like of the steel fiber are not particularly limited, but from the viewpoint of obtaining a high-strength molded product, a thickness of 0.5 mm or less and a length of 1 mm or more is preferable.

The carbon material raw material and the copper-coated steel fiber are blended at a predetermined compounding ratio and then sufficiently mixed to orient the steel fiber in one direction and then provided for molding.
The compounding amount of the steel fiber is not particularly limited, and a carbon / steel fiber composite material having high strength and excellent wear resistance can be obtained even at a high compounding ratio of 40 to 50% by volume.

In addition, the molded body obtained by molding is carbonized by a conventional method.
It can be a steel fiber composite. The carbonization temperature is 900 from the viewpoint of sufficiently developing the strength of carbon.
C. or higher is preferable. On the other hand, if the carbonization temperature exceeds 1100 ° C, the coating effect is reduced due to melting of the copper coating layer, and the strength of the composite material is reduced due to the transformation of the steel fiber itself, which is not preferable.

Example After regular grade petroleum coke was carbonized at 1000 ° C., it was placed in a vibration mill filled with stainless balls having a diameter of 10 mm and pulverized for 4 hours to obtain coke powder having an average particle size of 15 μm, which was used as a molding aggregate.

As the binder pitch, the coal tar pitch with a softening point of 240 ° C., which was obtained by processing coal tar under a reduced pressure of 100 mmHg at 440 ° C. for 2 hours, was crushed to 60 mesh or less. Using.

As a steel fiber, 0.05 mm x 0.05 mm x 3 m long
m low carbon steel fiber (material: SPPC-1B) was used. This steel fiber is immersed in a plating solution (composition shown in Table 1) in an amount of 80 times the weight ratio for a predetermined time, subjected to copper plating treatment, thoroughly washed with water and dried to give an average plating layer thickness of 0.3 μm.
And 0.5 μm of two kinds of copper-plated steel fibers were obtained. The average plating layer thickness was calculated from the nominal shape of the fiber, the weight of copper deposited, and the true specific gravity of steel fiber and copper.

22 parts by weight of coke powder, binder pitch
10 parts by weight and 68 parts by weight of steel fiber (all copper-plated fiber) were mixed and used as a raw material for molding. Here, the fiber ratio was set to about 30% by volume in terms of volume.

Next, load each material into a stainless steel mold with internal dimensions of 50 mm x 80 mm in such an amount that the dimension after molding will be 10 mm.
A magnetic field of 10,000 Gauss was applied to orient the steel fibers in one direction. After that, using a hydraulic press with a pressurizing capacity of 30 tons, pressurizing and heating molding (pressurizing at a molding pressure of 200 kg / cm ² to 550 ° C. at a heating rate of 5 ° C./min and holding for 1 hour and cooling). The width in which the steel fibers are oriented parallel to the long side
A molded body of 50 mm × length 80 mm × thickness 10 mm was obtained.

Subsequently, the obtained molded body was placed in a stainless steel container filled with powdered coke, and the temperature was raised at a temperature rising rate of 10 ° C / Hr in a nitrogen atmosphere at 1 ° C.
The temperature was raised to 000 ° C., the temperature was maintained for 4 hours and then cooled to obtain a carbon / steel fiber composite material.

10 mm x 10 from the obtained carbon / steel fiber composite material
A mm × 60 mm test piece was cut out and the bending strength and the Charpy impact value were measured. The cutting-out direction of the test piece was such that the direction of length 60 mm coincided with the direction of length 80 mm of the molded body.
The bending strength was measured with a bending span of 40 mm by pressing down from the portion that contacts the upper part during molding. The Charpy impact test was performed so that the impact direction was perpendicular to the pressing direction during molding.

8mm wide from the same carbon / steel fiber composite
Cut out a test piece with a length of 8 mm and a height of 10 mm so that the height direction matches the pressing direction at the time of molding, and use this test piece as the sliding surface with the surface that contacts the upper surface at the time of molding under the following conditions The thickness change of the test piece was measured after the abrasion test, and the abrasion volume per sliding distance of 100 km was calculated. The test piece was attached so that the steel fiber was perpendicular to the sliding direction.

Table 2 shows the measured bending strength, the Charpy impact value, and the wear amount. For comparison, Table 2 shows that Comparative Example 1 is the same as Comparative Example 1 except that the steel fibers having the same dimensions and no copper plating are oriented in one direction, and molded and fired by the same method. Dimensionally oriented steel fiber without copper plating in one direction and molded in the same way,
The result of firing is also shown in Comparative Example 2.

As is clear from the results shown in Table 2, the product of the present invention in which the steel fiber subjected to the copper plating treatment is oriented in one direction has a higher bending strength and impact than those of Comparative Example 2 using the steel fiber without the plating treatment. The strength is remarkably improved and the abrasion resistance is also excellent.

Effect of the Invention As described above, the carbon / steel fiber composite sliding plate according to the present invention has the effect of the unidirectional orientation of the steel fiber and the effect of the copper coating treatment applied to the surface of the steel fiber to carburize the steel fiber during carbonization. Since the reaction is sufficiently suppressed, the pantograph sliding plate using the carbon / steel fiber composite material of the present invention has remarkably excellent bending strength as compared with the conventional carbon sliding plate, and troubles such as breakage during use occur. Is extremely small, and the effect it brings is enormous.

Claims (1)

[Claims] 1. A pantograph sliding plate, which is a composite material in which steel fibers are oriented in one direction as a carbon material raw material, molded and carbonized, and the surface of the steel fibers is coated with copper. Carbon / steel fiber composite material.