JP2010242160A - Abrasion-resistant electroconductive member, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abrasion-resistant electroconductive member which has both of excellent abrasion resistance and high electroconductivity, and shows superior durability, and to provide a method for manufacturing the member. <P>SOLUTION: The manufacturing method includes making metal particulates which have a specific gravity of 5 or more and have a specific electric resistance of 14×10<SP>-6</SP>Ωcm or less, for instance, metal particulates formed of tungsten collide onto a surface of a substrate of a soft metal having a specific electric resistance of 5×10<SP>-6</SP>Ωcm or less, for instance, a substrate made from copper, thereby to form a structure in which the metal particulates are dispersed, on the surface of the substrate of the soft metal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is excellent in electrical conductivity and wear resistance, and is preferably used for various electrical contacts, electrodes, motor commutators and brushes, railway overhead wires (trolley wires), pantograph slip plates, and the like. The present invention relates to a wearable conductive member and a method for manufacturing the member.

The sliding part, which is the electrical contact between the pantograph slide plate and overhead wire used in high-speed railway vehicles such as the current railway vehicles, such as the Shinkansen, wears due to an increase in friction speed and an increase in current accompanying the increase in vehicle speed. Life is very short. For this reason, there is a very high need for the sliding member to achieve both conductivity and wear resistance.
However, the copper-based material used as the conductive material generally has extremely low wear resistance. On the other hand, in alloy steels and ceramic materials having excellent wear resistance, the conductivity is greatly deteriorated (electrical resistance is high), and there is no material that can maximize both characteristics. That is, it can be seen that the characteristics of conductivity and wear resistance are typical trade-off characteristics.

Therefore, at present, a copper alloy-based sintered material in which a copper-based material is used as a base material, various solid lubricants are mixed with the base material, and a material with improved wear resistance is mixed at the expense of conductive properties. Is used (see Non-Patent Document 1).
In addition, in order to improve the trade-off characteristics as described above, hard particles are shot on the surface of the electrode or nozzle tip, and the metal structure on the surface is refined to improve wear resistance ( Patent Document 1).

  However, in the technique described in the above cited document, since the metal material itself is a non-ferrous metal material typified by copper or the like, it adheres to the metal material that becomes the contact point of the sliding counterpart. It is difficult to greatly improve

Japanese Patent Laid-Open No. 8-150483

“Sliding Electric Contact and Layered Solid Lubricant”, Tribologist Vol. 53, No. 11 (2008), p. 731

  As can be seen from the above-mentioned prior art documents, there is a strong demand for the development of materials that can simultaneously exhibit excellent wear resistance and high electrical conductivity (low electrical resistance). According to such a material having both wear resistance and conductivity, it can be expected to be applied not only to power supply parts for railways with severe wear conditions but also to electrodes, electrical contacts, and mounting technology fields in the IT field.

  The present invention has been made in view of the above problems in conductive materials used for sliding parts of railway vehicles and various electric devices, and the object thereof is excellent wear resistance and high conductivity. And providing a wear-resistant conductive member that exhibits excellent durability and a method for producing such a member.

  In order to achieve the above object, the present inventors have conducted intensive studies such as materials and surface treatment. As a result, for example, electrically conductive soft metal materials represented by copper, hard metal fine particles represented by tungsten, and the like. It was found that the above-mentioned problems can be solved by dispersing metal fine particles below the surface of the soft metal, and the present invention has been completed.

The present invention is based on the above findings, and the wear-resistant conductive member of the present invention has a specific gravity of 5 or more below the surface of a soft metal substrate having a specific electric resistance of 5 × 10 ⁻⁶ Ω · cm or less. And fine metal particles having a specific electric resistance of 14 × 10 ⁻⁶ Ω · cm or less are dispersed.
In the method for producing the wear-resistant conductive member according to the present invention, the metal fine particles are formed on the surface of the soft metal substrate, that is, the soft metal substrate having a specific electric resistance of 5 × 10 ⁻⁶ Ω · cm or less. That is, it is characterized in that metal fine particles having a specific gravity of 5 or more and a specific electric resistance of 14 × 10 ⁻⁶ Ω · cm or less are collided to disperse the metal fine particles below the surface of the base metal.

According to the present invention, the specific electric resistance is 5 × 10 ⁻⁶ Ω · cm or less, and the surface of the soft metal substrate having a good conductivity has a high specific gravity of 5 or more, and the specific electric resistance is 14 × 10 ⁻⁶ Ω · cm or less metal fine particles having relatively good conductivity are dispersed, so that high conductivity and wear resistance can be exhibited at the same time, and the service life of the conductive member is improved. Can do.

It is a schematic explanatory drawing which shows the point of the ball-on-disk friction wear test in an Example. It is an EPMA analysis image which shows element distribution in the surface vicinity part of the disk test piece obtained by Example 1 of this invention.

  Hereinafter, the wear-resistant conductive member of the present invention will be described in more detail together with embodiments and manufacturing methods thereof. In the present invention, “%” means mass percentage unless otherwise specified.

As described above, the wear-resistant conductive member of the present invention has a specific gravity of 5 or more on the surface of a soft metal substrate having a specific electric resistance of 5 × 10 ⁻⁶ Ω · cm or less, and a specific electric resistance. It has a structure in which fine metal particles of 14 × 10 ⁻⁶ Ω · cm or less are dispersed in the base metal.
That is, the surface of a soft base material with good conductivity is dispersed with fine metal particles having a relatively high specific gravity and a relatively good conductivity, so that the base material is hardly damaged. The hardness of the surface can be increased and the adhesion resistance can be greatly improved by forming a dissimilar metal dispersion layer, making it possible to achieve both conductivity and wear resistance, and durability as a conductive member. Will be improved.

In the wear-resistant conductive member of the present invention, the specific resistances of the soft metal substrate and the metal fine particles are 5 × 10 ⁻⁶ Ω · cm or less and 14 × 10 ⁻⁶ Ω · cm or less, respectively. When the specific electric resistance of the material and the metal fine particles exceeds these values, the function as the conductive member is impaired due to the increase in electric resistance.
In addition, the specific gravity of the metal fine particles is set to 5 or more. When the specific gravity is less than 5, the energy when the particles are projected onto the soft substrate is insufficient, and thus the hardness increases due to dispersion on the surface. Is due to insufficient. In addition, as a typical example of the metal material satisfying such a condition, for example, tungsten or tantalum can be given. It is also possible to use a metal containing 50% or more of these metals.

  On the other hand, as the soft metal substrate, it is desirable to apply a Vickers hardness Hv of 150 or less, and specific materials include gold, silver, copper, or an alloy containing 50% or more of these metals. be able to. The reason why the Vickers hardness of the base material is preferably Hv 150 or less is that the projected particles are easily kneaded into the soft base material, and the metal fine particles are easily dispersed in the base metal by the manufacturing method described later. By becoming.

  The surface roughness of the wear-resistant conductive member of the present invention, that is, the roughness of the surface on which the fine metal particles are dispersed is desirably 1 to 10 μm at the maximum height roughness Rz defined in JIS B 0601. . When Rz exceeds 10 μm, the friction coefficient increases, but on the condition having the energy at the time of projection necessary to form the dispersion layer, it tends to be difficult to obtain a surface roughness of less than 1 μm. .

The wear-resistant conductive member of the present invention is obtained by dispersing fine metal particles made of the above material on the very surface of the soft metal base material made of the above material. It is inevitable that the value of the electrical resistance slightly increases due to the dispersion of the substrate as compared with the base material before the dispersion.
Needless to say, the increase in the resistance value is preferably as small as possible, but if the increase rate is less than 5%, the function as the conductive member is not substantially impaired, and the increase rate in the resistance value. It is desirable to disperse the metal fine particles to the extent that does not exceed 5%.
In addition, the increase rate of resistance value said here means the measured value by the method demonstrated in the Example mentioned later.

In addition, the wear-resistant conductive member of the present invention includes a hardened layer whose hardness is improved by the dispersion of metal fine particles on the surface, in other words, the dispersion of metal fine particles. The thickness of the hardened layer is desirably formed to a thickness of 1 to 50 μm.
That is, when the thickness of the hardened layer is less than 1 μm, the wear resistance cannot be sufficiently improved. Conversely, when the thickness exceeds 50 μm, the conductivity as the conductive member may be impaired. It depends. More preferably, the cured layer has a thickness of 5 to 20 μm.

In the present invention, the hardened layer means a region having a hardness of 10% or more with respect to the hardness of the original part of the soft metal base material. As long as it is the region, it is not necessarily limited to only the region where the fine metal particles are dispersed.
That is, the cured layer (second cured layer) in which the metal fine particles are not dispersed is cured at a position immediately below the cured layer (first cured layer) due to particle dispersion, that is, 10% or more is cured from the base material portion. The area | region may exist and the sum total thickness of these 1st and 2nd hardened layers should just be 1-50 micrometers.

The wear-resistant conductive member of the present invention is a soft metal substrate, such as metal fine particles, for example, on the surface of a soft metal substrate having a specific electric resistance of 5 × 10 ⁻⁶ Ω · cm or less, as represented by copper. Manufactured by colliding fine metal particles having a specific gravity of 5 or more and a specific electric resistance of 14 × 10 ⁻⁶ Ω · cm or less as represented by tungsten and dispersing the fine metal particles below the surface of the base metal. be able to.
As a result, the fine metal particles are embedded in the deformed or pulverized state under the surface of the soft metal base material and dispersed in the base metal to form the first hardened layer on the base material surface. In the position immediately below, the base metal is microscopically deformed by the collision of the particles, and a second hardened layer is formed by work hardening.

There are no particular limitations on the apparatus used for this, various conditions such as the size and collision speed of the metal fine particles, and the particle dispersion density as a result of the treatment, and the above-mentioned cured layer has a total thickness of 1 to 50 μm. As long as it can be formed to a thickness.
For example, as an apparatus for causing the metal fine particles to collide with the substrate, an air injection type or impeller type injection apparatus can be used. Further, as the fine metal particles, those having a mesh under of 53 μm, more preferably under a 10 μm mesh can be used, and the speed at the time of collision of the metal particles is desirably 50 m or more per second.

In the wear-resistant conductive member of the present invention, a tin fine particle dispersion layer or a diamond-like carbon (DLC) coating layer is formed on the surface (dispersed surface of fine metal particles). Can do. It is also desirable if necessary to form a dispersion layer of tin fine particles on the DLC coating layer formed on the surface of the wear-resistant conductive member.
By these, it is possible to reduce the friction on the surface of the base material, that is, the contact surface with the mating member, and to further improve the wear resistance.

The dispersion layer of tin fine particles can be formed by causing tin fine particles to collide with the surface thereof.
In addition, as a method for forming the DLC coating layer, for example, an ionization vapor deposition method, a sputtering method, an ion plating method, a plasma CVD method, a plasma ion implantation film formation method, a hollow cathode arc vapor deposition method, a vacuum arc vapor deposition method, or the like is applied. can do.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

(1) Preparation of disc test piece As a soft conductive base material, a tough pitch copper C1100 material (specific electric resistance: 1.67 × 10 ⁻⁶ Ω · cm) defined in JIS H 3100 is selected, and the diameter is 33 mm and the thickness is A 3 mm disk-shaped substrate was produced. This surface was polished to a roughness of Ra 0.02 μm.
Subsequently, pure tungsten (specific gravity: 19.3, specific electric resistance: 5.65 × 10 ⁻⁶ Ω · cm) or pure tantalum (specific gravity: 16.6, specific electric resistance: 12.5 × 10) as fine metal particles Using a fine particle comprising ⁻⁶ Ω · cm), the polishing surface was subjected to a projection treatment under various conditions to obtain disk test pieces (Examples 1 to 5).

For further friction reduction, the treated surface is further subjected to a projection treatment with tin fine particles (Examples 6 and 7), or the projection surface is lightly polished to form a smooth curved surface on a fine sharp convex portion. After the formation, a DLC coating layer was added by a CVD (Chemical Vapor Deposition) method (Examples 8 and 9).
In addition, as a comparative material with respect to these Examples, the non-processed test piece (comparative example 1) which consists of the said disk-shaped pure copper base material, the sintered alloy (Cu-30%) generally used for an electric sliding member A test specimen (Comparative Example 2) of the same size made of WS ₂ -6% Sn-1% Ag) and a disk specimen (Comparative Example 3) obtained by subjecting the disk-shaped pure copper base material to a projection treatment using silicon carbide particles. ) Was used.

(2) Investigation of projection processing surface About each obtained disk test piece, while measuring the maximum height roughness Rz of a projection processing surface based on JISB0601, using a needle-type surface roughness meter, metal The state of particle dispersion was observed.

(3) Thickness of hardened layer Using a micro Vickers hardness meter, the hardness distribution in the plate thickness direction of the base material in each disk test piece was measured by holding for 10 seconds at a load of 25 gf. The thickness of the region that was hardened by 10% or more relative to the hardness of the base material (base material part) was measured.

(4) Measurement of increase rate of electric resistance value As a base material for a test piece, a tough pitch copper C1100 material having a thickness of 0.5 mm and 100 mm × 100 mm was used. After performing the same process, it cut out to the strip shape of 10 mm x 40 mm, and was set as the test piece for an electrical resistance value measurement.
Then, both ends in the longitudinal direction of each strip-shaped test piece are sandwiched between electrical resistance terminals, the electrical resistance values are measured 5 times, the average value is obtained, and the resistance value of copper-sized tough pitch copper that has not been processed at all ( 0.4902Ω) as a reference “100”, and a ratio to the reference “100” was calculated.

(5) Friction and wear test Using each disk specimen obtained as described above, a ball-on-disk friction and abrasion test was performed to evaluate the friction and wear characteristics of the disk specimen.
That is, FIG. 1 is a perspective explanatory view showing the test procedure. As shown in FIG. 1, the ball B is arranged on the disk test piece D and the fixed ball B rotates. It slides on one side.

The ball B has a diameter of 4 mm and is similarly made of a tough pitch copper C1100 material, and is ground to a surface roughness of Ra 0.02 μm.
As indicated by the arrows in the figure, the ball B was pressed against the disk specimen D in the vertical direction with a constant load of 2N, and a 15 minute friction test was performed at a sliding speed of 0.05 m / s in the air at room temperature. went. At this time, along with the measurement of the friction coefficient, the amount of wear of the disk test piece (the maximum depth of the wear scar) and the surface roughness of the opponent ball indicating the severity of adhesive wear were also measured. Each disk test piece was tested in combination with a new ball.

  The test results described above are shown together with the processing conditions in Table 1.

  As a result, in Comparative Example 1 using a disk test piece made of tough pitch copper C1100 material that had not been subjected to any treatment, the electric resistance value was the lowest and the best conductivity was exhibited. Shows a very high coefficient of friction exceeding 0.5 and shows a large wear depth of the disk specimen, severe adhesion wear, and a significantly large surface roughness of the sliding trace of the opponent ball. The result is shown.

Further, in Comparative Example 2 using a disk test piece made of a sintered alloy used for the electric sliding member, although the friction coefficient by the frictional wear test is 0.24, which is a low value to some extent, the electric resistance As for the value, it was confirmed that the value was higher by one digit or more than that of the pure copper material (tough pitch copper) according to Comparative Example 1 described above.
Moreover, in the comparative example 3 by the disk test piece which performed the projection process using SiC which is a hard ceramic particle | grain to the disk-shaped base material which consists of pure copper materials (tough pitch copper), an electrical resistance value is low and electroconductivity is low. Although the wear depth is slightly improved by hardening of the disk surface in the friction test, the adhesion with the opponent ball becomes remarkable, and as a result, the wear amount of the disk test piece is also described in the following book. It has been found that the values are greater than those of the inventive examples.

In contrast to these comparative examples, in the examples of the present invention, the electrical resistance value is remarkably low (excellent in conductivity) as compared with Comparative Example 2 made of a sintered alloy used for the electric sliding member. In the friction and wear test, it was confirmed that the wear resistance was extremely excellent.
Furthermore, in Examples 6 and 7 in which tin fine particles were further projected onto the surface modified by the dispersion of fine metal particles, and in Examples 8 and 9 in which DLC was further coated on the modified surface, low electrical properties were obtained. It was found that the friction coefficient can be further reduced while maintaining the resistance value and the high wear resistance.

  FIG. 2 shows, as a representative example of the above example, EPMA analysis image information in the vicinity of the surface of the test piece obtained in Example 1. In the vicinity of the surface, the distribution state of Cu (copper) is shown. In the figure showing Cu, a reduced portion (red part) of Cu is recognized, while in the figure showing the distribution state of W (tungsten), a concentrated part of W shown in yellow to green is recognized, and the base metal It can be seen that tungsten is dispersed in copper.

  As described above, the present invention, for example, greatly improves the life by imparting excellent wear resistance to an electric sliding member made of a conductive soft base material such as copper. In addition to being able to maintain high conductivity, a high current can be passed, and this contributes to the miniaturization of a product motor or the like. Of course, in the electrical contact part where the frictional conditions are not so severe and in the mounting field in the IT industry, it is possible to contribute to the extension of the life of the contact part and the miniaturization of the package. Application fields are extremely large.

Claims (17)

Under the surface of the specific electrical resistance of 5 × 10 ^-6 Ω · cm or less of the soft metal substrate, having five or more specific gravity, and specific electric resistance 14 × 10 ^-6 Ω · cm or less of the metal fine particles A wear-resistant conductive member that is dispersed.   The wear-resistant conductive member according to claim 1, wherein the surface roughness is 1 to 10 μm in terms of a maximum height roughness Rz.   The wear-resistant conductive member according to claim 1 or 2, wherein the soft metal substrate has a Vickers hardness of Hv150 or less.   The wear-resistant conductive material according to any one of claims 1 to 3, wherein the soft metal substrate is gold, silver, copper, or an alloy containing 50% or more of these metals by mass ratio. Element.   The wear resistant conductive member according to any one of claims 1 to 4, wherein an increase rate of an electric resistance value due to the dispersion of metal fine particles is less than 5%.   The wear-resistant conductive member according to any one of claims 1 to 5, wherein the metal fine particles are tungsten, tantalum, or an alloy containing these metals in a mass ratio of 50% or more.   The wear-resistant conductive member according to any one of claims 1 to 6, wherein a hardened layer is provided under the surface of the soft metal substrate, and the thickness of the hardened layer is 1 to 50 µm.   8. The hardened layer comprises a first hardened layer in which the metal fine particles are dispersed in a base metal and a second hardened layer located immediately below the hardened layer. The wear-resistant conductive member described.   The wear-resistant conductive member according to any one of claims 1 to 8, further comprising a diamond-like carbon coating layer on a surface thereof.   The wear-resistant conductive member according to any one of claims 1 to 9, further comprising a tin fine particle dispersion layer on a surface thereof.   In manufacturing the wear-resistant conductive member according to any one of claims 1 to 10, the metal fine particles are made to collide with the surface of the soft metal substrate, and the metal fine particles are placed under the surface of the substrate metal. A method for producing a wear-resistant conductive member, characterized by being dispersed in   The manufacturing method according to claim 11, wherein an air injection type or impeller type injection device is used when metal fine particles collide with the surface of the soft metal substrate.   The method according to claim 11 or 12, wherein the velocity of the metal fine particles at the time of collision with the surface of the soft metal substrate is 50 m / sec or more.   The size of the said metal fine particle is 53 micrometers mesh under, The manufacturing method as described in any one of Claims 11-13 characterized by the above-mentioned.   The metal fine particles collide with the surface of the soft metal base material to disperse the metal fine particles below the surface of the base metal, and then the surface is coated with diamond-like carbon. 14. The manufacturing method according to any one of items 14.   15. The fine metal particles collide with the surface of the soft metal substrate, the fine metal particles are dispersed below the surface of the metal substrate, and then the fine tin particles collide with the surface. The manufacturing method according to any one of the items.   The metal fine particles collide with the surface of the soft metal substrate, the metal fine particles are dispersed below the surface of the substrate metal, and then the surface is coated with diamond-like carbon, and further tin particles are collided. The manufacturing method according to any one of claims 11 to 14, characterized in that:

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