RU2470898C1 - Material for producing contact current-collecting articles and method of producing said material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to materials for producing contact current-collecting devices, particularly for producing current-collecting inserts for railway transport and urban electric transport and techniques for production thereof. The material for producing contact current-collecting devices contains graphite and a coke residue, and is characterised by that it additionally contains coke and iron powder, with the following ratio of components, wt %: graphite - 5.0-30.0; coke - 50.0-80.0; iron powder - 0.5-1.5; coke residue - the balance.

EFFECT: high wear resistance of the current-collecting material with low current density and in the absence of current.

3 cl, 1 tbl

Description

The invention relates to materials for the manufacture of products of sliding contact current collection, for example, for the manufacture of current collector inserts for railway and city electric vehicles, current collection of lifting transport devices, electric brushes, and technologies for their production.

The patent RU 2075805 discloses a material for the manufacture of slip rings and a method for its manufacture.

The material includes the following components, wt.%: Ground waste of calcined carbon material 1-16, ground waste of graphitized carbon material 1-16, carbon aerogel 2-20, graphite 3-6, coke 6-32, binder - solid high-temperature pitch - the rest .

A method of manufacturing a material involves co-grinding and mixing carbon black, graphite, coke, carbon aerogel, waste calcined and graphitized carbon material and a binder in the following ratio of components, wt.%: Ground waste calcined carbon material 1-16, ground waste graphitized carbon material 1 -16, carbon-based airgel 2-20, graphite 3-6, coke 6-32, binder - solid high-temperature pitch - the rest, then a preform is formed from the resulting mixture, which is heat-treated melt at 1200 ° C and graphite at 2800 ° C. Conducting materials are made from the finished material, including current collection products.

The known invention allows to slightly reduce the duration of the joint grinding cycle, use low-cost components and realize the following advantages: the duration of the preparation of the press composition in the vibratory mill is reduced by 20-40%; the coefficient of friction is reduced by 15-30%; the wear of elements during their operation is reduced by 1.3-1.6 times; local overheating is eliminated.

The disadvantages of this known invention include a relatively high level of electrical resistivity of the inserts, due to the joint grinding and grinding of all components of the press mass, low arc resistance that does not allow their use for powerful and high-speed railway transport, as well as the need for high-temperature processing at 2800 ° C, significantly energy-intensive technology.

The closest material for the manufacture of contact slip to the proposed and the method of its manufacture are disclosed in patent RU 2150444.

In accordance with this patent, the material contains the following components, wt.%:

Natural Graphite Particles 10-90 Coke residue 5-20 Pyrolytic carbon 6-70

The method involves mixing particles of graphite and a binder, forming, by pressing from the finished mixture, a preform and its firing at 800-1100 ° C for 0.5-1.5 hours under conditions providing an open porosity of at least 10% and subsequent saturation of the obtained porous blanks with pyrocarbon.

The material is characterized by the following properties: compressive strength of 49 MPa, electrical resistivity of 2.8 μOhm · m, wear rate of the insert during friction with current collector - 0.1-0.14 mm per 1000 km, reduced wear by 2-5 times copper counterbody, the maximum permissible linear density of electric current above which catastrophic wear of the material and / or copper counterbody begins - more than 20 A / mm.

The disadvantages of the closest technical solutions include the relatively high wear rate at low current densities and when sliding without current.

The objective of the invention is to eliminate the inherent disadvantages of the known technical solutions.

The problem is solved by the material for the manufacture of contact current collection devices, including graphite and coke residue, in accordance with which it additionally contains coke and iron powder in the following ratio of components, wt.%:

Graphite 5.0-30.0 Coke 50.0-80.0 Iron powder 0.5-1.5 Coke residue rest.

The problem is also solved by the method of manufacturing this material, in accordance with which the particles of graphite, coke, binder and iron powder are mixed, then a workpiece is formed from the resulting mixture by pressing with a force of 80-120 MPa and the resulting workpiece is fired under conditions providing for carbonization of the binder.

In particular embodiments of the invention, high temperature petroleum or coal tar pitch is used as a binder.

The invention consists in the following.

The qualitative and quantitative ratio of the components of the material is selected from the following considerations.

Coke is necessary to ensure its own wear resistance and hardness of the material. Exceeding the coke content above the declared values leads to a significant increase in the electrical resistivity (RES), to increased wear of the contact wire and to a decrease in the arc resistance of electrical contact inserts. Its content below the declared values leads to a decrease in the mechanical properties of the material and to an increase in the wear rate of contact current collection products.

Graphite is necessary to ensure sufficient electrical resistivity, self-lubricating properties, and high arc resistance. Its increased content leads to a decrease in the mechanical properties of the insert. Its reduced content leads to a decrease in arc resistance and an increase in electrical resistivity. Graphite in the examples of implementation used natural, because it is attractive for its price, but can be used and artificial graphite.

Iron powder is necessary to provide the necessary wear resistance of the insert at high current values. Its increased content, beyond the claimed limits, leads to increased wear of the contact wire. Its reduced content leads to increased wear of the insert at high current values. When implementing the invention, a powder may be used. Powder is understood to mean such a state of a substance in which the solid substance that is part of it is very finely ground, and the particles of this substance are not connected to each other, which makes it possible to give their accumulation an arbitrary shape.

To achieve the declared technical result, the presence of all the claimed components in the stated ratios is important.

As a binder, any carbonizable material with a high coke residue can be used - oil and coal sands, phenol-formaldehyde resins, polyamide resins, etc.

For some embodiments of the invention, the use of high temperature pitch is most attractive. The use of such pitch provides the invention with the most optimal conditions for the production of materials operating in current collectors with a high current density.

In other implementations of the invention, it is possible to use thermosetting resins as a binder. In this case, the mechanical characteristics of the material are improved, however, the electrical properties are somewhat deteriorated, and the choice of binder depends on the specific operating conditions.

An example implementation of the invention.

Particles of graphite, coke, a binder — high-temperature coal tar pitch, and iron powder were mixed in calculated amounts in a closed rotating drum for two hours at a rotation speed of 60 rpm. Then, by pressing in steel closed mold with a force of 80-120 MPa, the preforms were formed, after which the preforms were subjected to carbonizing roasting at a temperature of 1000-1100 ° С and normal atmospheric pressure.

The resulting material was tested. Its operational properties were determined - the wear resistance of the insert and the wire interacting with it, hardness, electrical resistivity, and wear resistance under current.

Material properties depending on the composition are shown in table 1.

As follows from the data presented, the material shows an acceptable level of wear resistance at high current densities and excellent wear rate at low current densities and when sliding without current, which allows the material to be used in the production of contacts of both electric locomotives and electric trains.

It should be noted that even powerful electric locomotives, with the exception of high-speed transport, do not consume high currents constantly, but only during acceleration and during upgrades. The rest of the time they either consume relatively small currents, or move without current consumption. As a rule, carbon inserts with low electrical resistance, adapted for the consumption of high currents, have low mechanical properties. In this case, they will wear out relatively quickly when consuming low currents and without current. Conversely, carbon inserts with high electrical resistance wear out intensively when high currents are consumed. The proposed universal carbon inserts can be equally reliably operated at any current without jumps in the wear rate and without emergency wear replacements.

Composition, wt.% Resistivity, μOhm · m Hardness, HS Wear rate, conv. units: Coke Iron powder Graphite Coke. balance Insert The wire High current insert Low current insert Insert, no current fifty 0.5 thirty rest 13 48 2,3 one 3.9 1.8 1.8 80 one 10 27 69 1,5 2.1 2,8 1.3 1,1 60 1,5 18.5 19 63 1.8 1.4 1,6 1,5 1,5 70 one 5 thirty 75 2 3.3 4.8 1,2 one 65 one 9 27 70 1.3 2,8 3,7 1,2 one 63 0.5 23.5 16 53 one 1,2 4.1 1.4 1.3

Claims (3)

1. Material for the manufacture of contact current collection devices, including graphite and coke residue, characterized in that it additionally contains coke and iron powder in the following ratio of components, wt. %:
Graphite 5.0-30.0 Coke 50.0-80.0 Iron powder 0.5-1.5 Coke residue Rest 2. The method of manufacturing the material according to claim 1, characterized in that the particles of graphite, coke, binder and iron powder are mixed, the workpiece is formed from the resulting mixture by pressing with a force of 80-120 MPa, and the subsequent baking of the obtained workpiece under conditions providing for carbonization of the binder . 3. The method according to claim 2, characterized in that as a binder use a high temperature oil or coal tar pitch.