RU2455400C2 - Method for electrolytic-plasma treatment of surface of conductive products - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method involves pulling the product through the reactor of electrolyte-plasma treatment, the body of which is made of a non-conductive material to form the upper and lower symmetrical zones of the reactor, pumping of electrolyte flow through the upper and lower zones of the reactor and then through a hole in its anodes, launch of a plasma process by increasing the voltage at the anode and the surface of treated products in the pumped electrolyte. During a volt rise in the space between anodes and the workpiece the gas is fed under pressure through nozzles, the consumption of which is reduced until complete cessation of feeding, when a sustainable plasma process is achieved, and consumption of electrolyte is increased to the working level.

EFFECT: reduced time loss, power consumption and surface defects, in addition, the treatment can be performed without pre-heating of the electrolyte.

2 cl, 1 dwg

Description

The invention relates to the field of electrolyte-plasma surface treatment of conductive rolled products and can find application in the implementation of technological operations of cleaning and etching of metals and alloys.

A known method of surface treatment, including exposure to the surface of the cathode product by electric discharge plasma during forced supply of electrolyte into the interelectrode space between the cathode and the anode, the anode being mounted equidistant to the surface being treated. (RU 96104583 A, C25D 5/00, published 02/27/1998)

The disadvantage of this method is the formation of surface defects at the stage of voltage rise to the ignition value of plasma discharges U _KP on the surface of the product, since the voltage rise at high current densities with the release of significant energy. At elevated temperatures and the occurrence of plasma discharges, a foamed electrolyte is formed with significant resistance, which ensures the occurrence of plasma discharges on the surface of the product at lower current densities. This dramatically reduces the likelihood of burns and other defects on the surface of the product, reducing the quality of processing.

The closest in essence and the technical result achieved is a method of electrolyte-plasma treatment of the surface of conductive rolled metal on the cathode, including pulling the product through an electrolyte-plasma treatment reactor, the casing of which is made of conductive material with the formation of upper and lower symmetric zones of the reactor, pumping the flow of electrolyte through the upper and the lower zone of the reactor and then through the holes in its anodes, starting the plasma process by increasing the voltage at the anodes and surface treatment of the product in the pumped electrolyte. According to the known method, the electrolyte is obtained in separate sections of the preparation in the form of foam and then forcedly pumped through the anode with holes through the reaction chamber (reactor). The formation of foamed electrolyte is carried out by passing a constant electric current through the electrolyte at a voltage of 150 ± 20 V. (RU 2149930, C25F 1/00, published on 05.27.2000)

The disadvantage of this method is the significant cost of electricity and the difficulty of forming a hot electrolyte with a temperature of at least 75-80 ° C. In addition, when the stationary course of the known method is terminated for a variety of reasons (a sharp increase in the electrolyte flow, voltage drop at the anodes, a forced shutdown of the production line due to production reasons with the reactor disconnected from the power source, etc.), it is difficult to restart the process in a minimum amount of time ignition of plasma discharges. The resumption of surface treatment of conductive rolled products takes a fairly long time, which reduces the productivity of the method, leads to an increase in energy consumption for heating the electrolyte.

The objective and technical result of the invention is to reduce the loss of time, energy consumption and surface defects due to local heat during processing of conductive products. In addition, surface treatment of products can be carried out without preheating the electrolyte.

The technical result is achieved by the fact that the method of controlling the electrolyte-plasma surface treatment of conductive products includes pulling the product through the electrolyte-plasma treatment reactor, the casing of which is made of conductive material with the formation of the upper and lower symmetric zones of the reactor, pumping the electrolyte flow through the upper and lower zones of the reactor and then through the holes in its anodes, starting the plasma process by increasing the voltage at the anodes and processing the surface of the product in pumped electrolyte, while increasing the voltage into the space between the anodes and the product through the nozzles, gas is supplied under pressure, the supply of which, when a stable plasma process is achieved, is reduced until the supply is completely stopped and the electrolyte consumption is increased to the working level.

The technical result is also achieved by the fact that carbon dioxide, inert gases or nitrogen are used as the gas.

The implementation of the method according to the invention can be illustrated by example using the installation of electrolyte-plasma processing, shown in figure 1, where:

1 - reactor;

2 - current-conducting pipes for supplying electrolyte;

3 - anodes with holes;

4 - locking rollers;

5 - wires;

6 - inputs of the nozzle nozzle system;

7 - processed conductive product;

8 - lower and upper zones of the reactor 1;

9 - the space between the anodes 3 and the surface of the product 7;

10 - pipeline;

11 - grounding rollers.

Through the reactor 1 of the electrolyte-plasma treatment installation, the casing of which consists of upper and lower symmetric zones made of a non-conductive material, the processed conductive product 7 is pulled in the direction D: steel sheet, bar, wire, long steel, etc. An electrolyte is supplied from the external hydraulic network to the input A of the non-conductive pipes 2, which is pumped through the reactor 1, supplying the electrolyte first to the upper and lower symmetric zones 8 of the reactor, and then through the holes in the anodes 3 of the reactor to the space 9 between the anodes 3 and the corresponding surfaces of the product 7. The loss of electrolyte, as well as the unintended exit of gases and vapors generated during the implementation of the method, is prevented by locking rollers 4. The output of spent electrolyte, vapors and gases is carried out through openings in the end face the reactor vessel 1 and the pipeline 10, which is connected to the successors and the spent electrolyte tank by the exit C. To ensure the functioning of the electrolyte-plasma surface treatment of the product 7 through the reactor 1, the electrolyte is continuously pumped.

Anodes 3 are connected to the positive pole of a constant or unipolar pulsed current source using wires 5. The electric circuit is closed through a conductive electrolyte located in the reactor 1, conductive article 7, grounding rollers 11 and grounding of the negative pole of the current source.

With an increase in the voltage supplied to the anodes from an external source of electric current, gas is injected under pressure into the space 9 between the anodes 3 and the product 7 through the nozzle system 6 of the nozzles from the external network, which foams the electrolyte, thereby increasing the electrical resistance of the electrolyte between the anodes 3 and the corresponding surfaces of the workpiece 7. Therefore, the achievement of the ignition voltage of microplasma discharges U _KP and the start of the plasma process on the surface of the workpiece 7 occurs when lower current densities and at any temperature of the foamed electrolyte, including at temperatures below 80 ° C. The resumption of the plasma process also easily occurs after sudden stops pulling the product 7, as well as with sharp increases in the speed of drawing the product 7, turning off the current, i.e. in situations requiring repeated starts of the plasma process.

The start of the plasma process is carried out by manually controlling the gas supply to the reactor 1 through a system of nozzles 6 nozzles with simultaneous control of the voltage at the anode or using an automatic control system for the entire process of electrolyte-plasma processing of products.

Upon reaching a stable plasma process of processing the product, the gas supply is reduced until the supply is completely stopped and the electrolyte flow rate through the reactor 1 is increased to the operating level.

In the case of surface treatment of conductive products in order to remove scale, oxide films or technological grease, it is more efficient to use an aqueous solution of sodium bicarbonate as an electrolyte, and carbon dioxide CO ₂ as a gas. In the case of surface treatment of products using aqueous solutions of salts of zinc, aluminum, nickel (ZnSO ₄ , Al ₂ (SO ₄ ) ₃ , NiSO ₄ ), etc. with the formation of protective coatings, it is more efficient to use nitrogen or inert gases as a gas.

For processing steel strip made of 08KP steel 1 mm thick and 200 mm wide in a 10% solution of sodium bicarbonate with a temperature of 65-70 ° C in a reactor with an interelectrode gap of 10 mm, the voltage of the stable plasma process was 125-135 V at a rate of increase of 25-30 V / min, and the flow rate of electrolyte and carbon dioxide amounted to 5-8 l / min and 4-7 l / min, respectively. The speed of the tape provided a surface treatment time of 0.2-0.5 seconds. The pressure of carbon dioxide in the nozzle line with a diameter of 0.2-0.3 mm was 3-4 atm., And the pressure of the foamed electrolyte inside the reactor was 1.1-1.2 atm.

Claims (2)

1. The method of controlling the electrolyte-plasma surface treatment of conductive products, including pulling the product through an electrolyte-plasma treatment reactor, the casing of which is made of conductive material, with the formation of upper and lower symmetric zones of the reactor, pumping the electrolyte flow through the upper and lower zones of the reactor and then through holes in its anodes, starting the plasma process by increasing the voltage at the anodes and treating the surface of the product in the pumped electrolyte, characterized it that when the voltage to the space between the anodes and the workpiece is fed through the nozzle under pressure, which when the steady flow of the plasma process is reduced to a complete cessation of flow and increase the flow of electrolyte to the working level. 2. The method according to claim 1, characterized in that the gas used is carbon dioxide, inert gases or nitrogen.