CS208262B1 - Kovografit shear for electric traction - Google Patents

Abstract

Metal-graphite skids for electric traction for collecting electric current, made by pressing and washing powders of copper, lead, graphite, molybdenum and iron. This mixture contains 0.1% by weight of pure cadmium or compounds corresponding to this cadmium content.

Description

The invention relates to metal-graphite bushings for electric traction, which increase the service life of the bushings and copper overhead line.

So far, various materials have been used for the shear contact to collect electric current, either conductive dense copper, carbon, or a shear contact made by powder metallurgy based on powdered iron. Carbon and in some cases impregnated with metal.

All the Skids used so far have a disadvantage of either rapid wear of the Skid or excessive wear of the overhead electrical line made of Cu drdt.

Carbon skid cannot withstand higher current loads and therefore cannot be used for the new series of electric locomotives.

Slides made by powder metallurgy from powdered iron with other additives have a short service life and high wear of the overhead line.

Shears made of carbon impregnated with metal have a good service life. This method is very laborious and requires technological equipment - such as a vacuum-pressure autoclave operating above the melting point of the impregnating metal.

These shortcomings are eliminated by metal-graphite slips for electric traction, which are made by pressing and sintering copper, lead, graphite, molybdenum silicon and iron, according to the invention, the essence of which is that they further contain 0.1 to 1% by weight of pure cadmium or its compounds in amounts corresponding to this cadmium content.

Existing technological equipment can be used for their production. Raw materials prepared by sieving and are mixed in a drum or arm mixer at room temperature of 20 to 25°C. Homogenization is checked by chemical analysis. The blanks are pressed into the desired shape with a hydraulic press to the prescribed apparent bulk density at a pressure of 150 to 250 Pa/cnA. After pressing, an appearance check and a bulk density check are carried out. The finished pressings are placed in steel or carbon containers so that there is no deformation during sintering. Either a continuous or periodic sintering furnace with a guaranteed reducing atmosphere or an inert atmosphere is used. The sintering is carried out at a temperature common for metal-graphite materials of 700 to 850°C.

The composition of the mixture for the above procedure is n following ? Copper powder 70 until 90 % wt. Lead powder 3 until 10 % iron powder 1 until 7 % « Nickel powder 0.5 until 3.5 % * Molybdenum sulfide 0.5 until 3.5 % « Graphite 0.5 until 5 % H Cadmium oxide 0.1 until 1 % M

The final values of the metal-graphite shear aa range from:

Bulk density 7 to 7.5 HBr Hardness 30 until *5 Electrical resistance ohm.mm /m 0.06 until 0.10 Shock resistance 1.2 until 1.8

After sintering, the bulk density, hardness, electrical conductivity, fracture strength and impact strength are checked again. When the products meet the required parameters, the opfit208 282 pressing and calibration are performed, which gives the product the final shape according to the production requirement.

The contact strips produced in this way are characterized by a high service life of approximately 80,000 km and reduce the wear of the contact wire by an average of twofold. The main advantage of these contact strips is the fact that they are able to cooperate with contact strips made of carbon, which cannot cooperate well with trivalent dense copper or powdered iron.

Claims (1)

OBJECT OF THE INVENTION Metallic graphite shear for electrical traction produced by compressing and baking a mixture of powders with media, lead, graphite, molybdenum and iron silicon, characterized in that they further contain 0.1 to 1 wt. of pure cadmium or its compounds in amounts corresponding to this cadmium content.