A method for preparing a conductive layer on the surface of a rail

Abstract

The invention provides a method for preparing a conducting layer on the surface of a steel rail. The preparing method overcomes the shortcoming of traditional electric-arc welding and is easy to implement on site. The preparing method is characterized in that a high-temperature molten drop preparation device with an electric arc or a laser serving as a heat source is utilized to heat a metal wire material; obtained molten high-temperature molten drops hit the surface of the steel rail and are spread; and metallurgical combination is completed only relying on the heat carried by the high-temperature molten drops. In the high-temperature molten drop preparation device with the electric arc serving as the heat source, the electric arc is produced in a hollow anode and the wire material end, and the heat generated by the electric arc in the anode position is taken away through circulating cooling water. In the high-temperature molten drop preparation device with the laser serving as the heat source, the laser sent out from a laser device directly heats the wire material end, and the molten high-temperature molten drops at the wire material end fall down under the action of gravity and are spread on the surface of a base metal in a hitting mode. The high-temperature molten drop preparation device with the electric arc serving as the heat source is adopted to prepare a nickel coating, the thickness of a metallurgical combining layer is about 10 microns, and the requirement is met.

Description

Technical field: [0001] The invention belongs to the field of railway signals, and relates to a method for preparing a conductive coating on the surface of a rail and related materials. Background technique: [0002] Railway track circuits play a vital role in the transmission of train control information, which has a direct impact on traffic safety and transportation efficiency. The poor phenomenon of track circuit shunting caused by the rust of the rail surface will cause the signal to be opened incorrectly, which will not only delay the operation of the train, affect the operation efficiency and economic benefits, but also bring huge safety hazards to railway transportation and production safety. [0003] In order to overcome the problem of poor circuit shunting caused by rust on the surface of the rail, the current method usually used is to prepare an anti-rust conductive metal layer on the surface of the rail by surfacing, thermal spraying, electroplating, or directly w...

AI Technical Summary

Problems solved by technology

The advantage of using methods such as surfacing or welding steel strips is that the prepared conductive layer is metallurgically bonded to the rail substrate, and the coating has a long rolling life. However, since the rail itself is high-carbon steel, the heat input of the arc to the substrate is relatively large. , the welding heat-affected zone is very easy to form martensitic structure and cause cracking

In order to avoid the formation of martensite in the heat-affected zone during the welding process, it is necessary to preheat the rail as a whole to above 300 degrees, which is difficult to achieve on-site construction, and this will cause serious problems of rail deformation and residual stress

The conductive layer is prepared by thermal spraying method, and the substrate can not be affected by heat, but the conductive coating and the substrate are mainly mechanically bonded, the bonding force is poor, and it is not resistant to rolling.

The electroplating method to prepare the conductive layer has strict requirements on the pre-treatment of the rail, and it is not suitable for on-site implementation. Moreover, the coating deposition efficiency is low, there are many pores, and the corrosion resistance and weather resistance of the coating are poor.

[0004] When the fusion welding method is used, the arc will directly act on the base material, and the heat input is relatively large. In recent years, STT, CMT and other methods have emerged to control the droplet transfer process when the wire is melted through digital circuits, which can reduce the droplet transfer process. arc current, thereby effectively reducing the heat input to the base metal, but the thermal effect of the arc on the base metal still exists, and martensite is still easily formed in the heat-affected zone of the rail

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