JPH03207837A - Ferrous sintered current collecting-sliding material - Google Patents

Abstract

PURPOSE:To obtain the current collecting-sliding material excellent in mechanical characteristics, electric characteristics, wear resistance and lubricity by mixing Fe powder with the powder of hard Cr-N compounds or hard Cr-C compound, subjecting the mixed powder to compacting the sintering and thereafter impregnating Pb therein. CONSTITUTION:As a current collecting-sliding material for collecting electric power from a trolley wire, iron powder is mixed with the powder of 100 to 200 mesh of hard Cr-N compounds such as Cr2N and CrN or hard Cr-C compounds such as Cr3C2 and Cr7C3 in the ratio of 0.5 to 20wt.%. The mixed powder is compacted into the shape of a current collecting body and is thereafter sintered in an atmosphere of a nonoxidizing gas such as an ammonia decomposed gas, an N2 gas, an H2 gas, an Ar gas and an He gas or in vacuum. Pb is placed on the sintered body and heating is executed in a nonoxidizing atmosphere to melt and impregnate Pb into the sintered body in the radio of 2 to 20wt.%. The current collecting-sliding material by an Fe-series sintered body, owing to the impregnation of Pb, improved in lubricity, excellent in wear- reducing effect for a trolley wire and mechanical strength and free from the increase in electric resistance to current collecting can be manufactured.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a ferrous sintered current collector sliding material.

Prior art and its problems Characteristics required of a current collector sliding material include, for example, low aggressiveness against the mating trolley wire, sufficient abrasion resistance, and mechanical strength. One example is its low electrical resistance.

Especially when considering the maintenance and lifespan of the trolley wire, the most important characteristic is that it is less aggressive. In order to reduce aggressiveness, it is absolutely necessary to lower the hardness of the material and to increase its lubricity. It is advantageous that the material is soft and has good lubricity, since these tend to coincide. That is, when a lubricant is added, the softer the material, the more likely the lubricant will protrude, and therefore the chance of the lubricant coming into contact with the other material increases. However, in conventional sintered alloys for current collector sliding, various metals are added to the base mainly composed of Fe or Cu to improve wear resistance. Diffusion into the base is significant, and with the hardening of the material, the lubricity inevitably decreases, resulting in increased aggressiveness against the trolley wire.

Furthermore, since the electrical resistance increases with the addition of metal, this method limits the amount of the element used as a lubricant to a fairly small amount, which further accelerates the deterioration of lubricity. Furthermore, together with the increase in electrical resistivity, these elements extremely reduce the mechanical strength, especially the impact value. Elements used as lubricants also act in a similar manner, so the amount added is also limited from the viewpoint of mechanical properties. In other words, metals added mainly for the purpose of improving wear resistance have a negative effect on most factors such as aggressiveness to trolley wires, electrical resistivity, and impact value, and this has caused the wear resistance of conventional sintered current collector sliding materials to deteriorate. This is a cause that has been considered to be a contradiction in terms of having both lubricity and lubricity.

Means for Solving the Problems The present invention aims to solve or alleviate the problems by using Fe.
The object of the present invention is to provide a current collecting sliding material which has a base containing as a main component as soft as possible to reduce its attack on trolley wires and has excellent abrasion resistance. In other words, the present invention is characterized in that wear resistance is mainly improved by Cr-N and/or Cr-C by adding only the minimum amount of metal to maintain the mechanical properties and electrical properties at predetermined values. This relates to iron-based sintered current collector sliding materials.

In the present invention, Cr-N and/or Cr-C includes C
Cr2N, CrN as r-N, Cr as Cr-C
3 C2 and Cr7 C3, both of which act as antiwear agents, are preferably used as particles of, for example, about 100 to 200 mesh.

Furthermore, since the part that actually acts as an anti-wear agent is limited to the very surface of the particles, desired wear-resistant properties can be obtained by adjusting the particle size. The amount of Cr-N and/or Cr-C is preferably about 0.5 to 20% by weight. In this range, sufficient wear resistance, lubricity, and mechanical strength can be obtained.

The sintered current collector sliding material of the present invention is characterized by containing the above-mentioned Cr-N and/or Cr-C, and the other configurations may be the same as those of a normal iron-based sintered current collecting sliding material. Therefore, Fe or an alloy containing Fe as a main component can be used as a normal base component. Further, in the present invention, metals and the like that are normally added to sintered current collector sliding materials can be added in the minimum amount that maintains the mechanical properties and electrical properties at predetermined values. Examples of these metals include Ni, Mo
, Cu, Fe, Cr, P and alloys of these metals, typical examples include FeMo, FeCr, CuCr, etc. At least one or more of these can be added and usually about 0.3 to 15% by weight However, in the present invention, the amount of these metals can be reduced compared to conventional methods, and it is particularly preferable to use the amount of these metals in the range of about 0.3 to 10% by weight.

In the present invention, in addition to the above, WS2, WO 82 may be used as necessary.
, C (graphite), a lubricant such as boron nitride, etc. can also be added.

The sintered current collector sliding material of the present invention is a mixture of the above-mentioned base components, some metals, and other additives as necessary, and Cr-
It is obtained by adding N and/or Cr-C, shaping and sintering. The molding is approximately 2. 5-7. 5 tons
/cm2, and sintering is usually preferably carried out at a temperature of about 900 to 1300°C. The sintering is preferably carried out in a nitrogen or ammonia decomposition gas atmosphere, in a gas atmosphere such as argon, hydrogen, helium, etc., or in a vacuum atmosphere.

According to the present invention, in the sintered body obtained as described above,
As shown in Japanese Unexamined Patent Publication No. 63-62852, the lubricity of the sintered body can be further improved by infiltrating lead, which is a soft metal that exerts a lubricating effect. The amount of lead to be used can be about 2 to 20 parts by weight based on 100 parts by weight of the sintered alloy containing Cr-N and/or Cr-C by an impregnation method. If the amount of lead is less than 2 parts by weight, the effect of reducing wear on the contact wire will be insufficient, while if it exceeds 20 parts by weight, the abrasion resistance and mechanical properties of the current collector sliding material will deteriorate, which is not preferable.

As an infiltration method for incorporating lead, for example, a lead piece of a predetermined weight is placed on a sintered alloy, and the lead is infiltrated for 10 minutes in a reducing or neutral atmosphere.
The lead may be introduced into the pores of the sintered alloy by heating to 00 to 1100°C. The current collector sliding material of the present invention containing lead obtained in this way can be used in cases where external lubrication etc. are not possible.
Particularly effective.

In the sintered current collector sliding material of the present invention obtained as described above, the hardness of the matrix can be any value higher than that of the pure sintered body, but the mechanical strength, lubricity, (for example, trolley wire), the Brinell hardness is usually less than about 120, especially about 1.
15 or less is preferable. Within these hardness ranges, a lubricant added as necessary can sufficiently exhibit its effect.

Effects of the Invention The sintered current collector sliding material of the present invention has excellent mechanical properties and electrical properties, as well as good wear resistance and lubricity, and is particularly less aggressive against the mating material, the trolley wire.

Example The present invention will be explained more clearly with reference to Examples below.

Examples 1 to 7 and Comparative Examples 1 to 5 Samples were prepared by mixing each of the components shown in Table 1 except for lead, and 6 tons were prepared.
/cm2, and in ammonia decomposition gas, 1120
C. for 90 minutes to produce sintered bodies mainly containing Fe, Examples 1, 2, 3.5, 7, and Comparative Examples 1.3.
Regarding No. 4, a lead piece of a predetermined weight was placed on the obtained sintered alloy and heated at 1080° C. for 90 minutes in an ammonia decomposition gas atmosphere to infiltrate lead into the sintered alloy. still,
Table 1 shows the blending amounts (wt%) of components other than Fe.

Therefore, all components other than those shown in Table 1 are Fe,
For example, in Example 1, Fe is 100-(2+0.5+5
)=92.5% by weight is used.

Table 2 shows the physical properties of the obtained sintered body, and Table 3 shows the wear test results.

The above wear test was carried out using the obtained slider plate with dimensions of 10 x 2.
A 5 x 90 mm piece was cut out and used as a test piece for current collector sliding wear. The test conditions were a pressing force of 5 kg/cm", a current of AC (21 V) IOOA and 300 A, and a sliding speed of 1.
00 km/h, and the test time was 5 minutes. The mating trolley wire was made of hard copper wire, which was wound to a diameter of 385 mm and had a contact sliding surface with a width of 6 mm. In this case, the eccentricity of the slider plate was set to 10 mm, similar to the usage conditions of a pantograph on a train. Among the test items, the amount of wear on the slider plate was measured by removing the sample after each test and measuring the remaining weight and remaining size using a micrometer.

Evaluation of the sample surface condition and trolley surface condition is as follows.

◎ Very good ○ Good Δ Slightly poor × Bad Table 2 As is clear from Tables 1 to 3 above, when the products of the present invention obtained in Examples 1 to 7 were used as current collector sliding materials,
It is clear that the trolley wire is not damaged and the wear resistance is further improved.

(that's all)

Claims (2)

[Claims] (1) An iron-based sintered current collector sliding material containing 0.5 to 20% by weight of Cr-N and/or Cr-C. (2) An iron-based sintered current collector consisting of 100 parts by weight of an iron-based sintered alloy containing 0.5-20% by weight of Cr-N and/or Cr-C and 2-20 parts by weight of lead. dynamic material.