EP0416099A1 - Method for electrochemically treating articles made of conductive materials - Google Patents

Abstract

The method consists in supplying a voltage of positive polarity of 200 to 400 V to the workpiece to be machined and immersing it in an aqueous electrolyte solution with a concentration of 2 to 12% by mass at a temperature of 40 to 95 ° C. <IMAGE>

Description

Technical field

The present invention relates to machining methods on the electrochemical and electrophysical way and relates in particular to methods for the electrochemical machining of workpieces made of electrically conductive materials.

Underlying state of the art

Das Elektropolieren wird bei einer Anodenstromdichte von 50 bis 60 A/dm² und einer Haltezeit von 3 bis 15 Minuten durchgeführt.A method for the anodic electropolishing of steel workpieces with direct current in a chromium-phosphorus-sulfuric acid electrolyte is known (see AM Jampolsky "Etching of metals", publisher "Metallurgia" (Moscow), 980, 5. 51 /, the by immersing the workpieces in an electrolyte at a voltage of 10 to 25 V and a temperature of 30 to 70 ° C, the electrolyte having the following composition in mass%:

The electropolishing is carried out at an anode current density of 50 to 60 A / dm 2 and a holding time of 3 to 15 minutes.

It is also a process for electropolishing workpieces made of copper and its alloys by electrolysis in an electrolyte based on an aqueous phosphoric acid solution (solution density ρ = 1.60 g / cm²) (AM Jampolsky "Etching of Metals", Verlag Metallurgia / Moscow / , 1980, p. 99) and in an electrolyte which contains 385 g of potassium pyrophosphate and 853 g of water, at a temperature of 20 to 50 ° C. within 1.5 to 3 minutes. (SU, A, 177732).

A process for the electropolishing of workpieces made of aluminum and its alloys in an electrolyte with a sulfuric acid concentration of 20 to 25% by mass at a temperature of 18 to 20 ° C. and a voltage of 6 to 12 V is known (Witt C. "Galvanotechnik" , 1981, V 72, H. 10, pp. 1073 to 1075).

The methods mentioned are based on the use of highly concentrated solutions of costly and toxic substances, are characterized by lengthy polishing and require a long-lasting preparation of the workpiece surface for electropolishing, which includes degreasing, etching, washing, etc., for their implementation. This leads to a reduction in the performance of the process and requires additional energy and labor.

A method for the electrochemical machining of workpieces made of electrically conductive materials is known, which involves machining the workpieces at a voltage of 220 to 230 V using a 20%

Aqueous ammonium chloride solution as an electrolyte at a temperature of 35 ° C comprises (V. N. Duradzhy "electron beam processing of materials", 1978, H. 5, pp. 13 to 17).

With this method, a surface roughness of less than R _a = 0.28 to 0.32 µm cannot be achieved and a reflection coefficient of over 30 to 40% cannot be achieved. The implementation of this method also requires the use of an electrolyte of a relatively high concentration (20%), which leads to an increase in the expenses for machining the workpieces.

Disclosure of the invention

The present invention has for its object to develop a method for the electrochemical machining of workpieces made of electrically conductive materials, in which the choice of machining conditions and the electrolyte concentration allows the performance in machining when using weak, cheap and non-toxic electrolytes increase, improve the quality of polishing and do without preparatory work for the surface of the workpieces.

The object is achieved in that in a method for the electrochemical processing of Workpieces made of electrically conductive materials, which consists in that the workpiece to be machined is supplied with a voltage of positive polarity and this is immersed in a heated aqueous electrolyte solution, according to the invention the workpiece to be machined is supplied with a voltage of 200 to 400 V, while the temperature of the aqueous Electrolytic solution, with a concentration of 2 to 12 mass% is 40 to 95 ° C.

To increase the polishing quality by increasing the reflectivity and reducing the surface roughness of workpieces made of corrosion-resistant chromium-nickel steels, it is expedient that the workpiece to be machined is supplied with a voltage of 240 to 320 V, and an aqueous ammonium sulfate solution with a concentration of 2 to 6% by mass at a temperature of 40 to 80 ° C is used as an aqueous electrolyte solution. When electropolishing composite workpieces made of chrome-nickel steels, it is expedient that the workpiece to be machined is supplied with a voltage of 330 to 380 V and an aqueous potassium sulfate solution with a concentration of 1 to 10% by mass at a temperature of 70 to 90 ° C is used as an aqueous electrolyte solution.

To remove enamel coatings from wires, a voltage of 200 to 210 V must be supplied to the workpiece to be machined and an aqueous sodium hydroxide solution with a concentration of 8 to 12% by mass at a temperature of 40 to 50 ° C must be used as the aqueous electrolyte solution.

When polishing workpieces made of non-ferrous metals and. e.g. Copper and their alloys, it is desirable that a voltage of 220 to 400 V is supplied to the workpiece to be machined and an aqueous solution of potassium aluminum alum with a concentration of 0.5 to 8% by mass at a temperature of 40 to 90 ° C as an aqueous electrolyte solution is used.

To reduce the electrolyte concentration, it is expedient to apply a voltage to the workpiece to be machined from 220 to 400 V and supply an aqueous solution of disubstituted ammonium citrate with a concentration of 0.5 to 6% by mass with the addition of sodium carbonate with a concentration of 0.5 to 3% by mass at a temperature of 40 to 90 ° C as an aqueous To use electrolytic solution.

It is also appropriate that the workpiece to be machined is supplied with a voltage of 220 to 400 V and an aqueous solution of sodium salt of ethylenediaminetetraacetic acid with a concentration of 0.5 to 6% by mass at a temperature of 40 to 90 ° C is used as the electrolyte solution .

When electropolishing workpieces made of low-carbon steels, it is advisable to supply the workpiece to be machined with a voltage of 240 to 330 V and an aqueous ammonium chloride solution with a concentration of 0.5 to 3% by mass at a temperature of 81 to 95 ° C as an aqueous electrolyte solution to use.

To increase the operating time of the electrolyte, it is necessary that ammonium thiocyanate with a concentration of 0.3 to 3% by mass is additionally introduced into the electrolyte as an additive.

To increase the reflectivity of the machined surface and to reduce the surface roughness when electropolishing aluminum workpieces, it is necessary to apply a voltage of 260 to 400 V to the workpiece to be machined and an aqueous solution of iron (III) chloride with a concentration of 0 , 5 to 3% by mass at a temperature of 70 to 90 ° C to use as an aqueous electrolyte solution.

The present invention makes it possible to use the method to be patented for the electrochemical machining of workpieces made of electrically conductive materials for polishing and for cleaning the workpieces made of rustproof, tool, low-carbon steels, copper and its alloys, made of aluminum and other materials, cleaning and to combine polishing in one process, applying force to the work to be machined Exclude workpiece completely; it also ensures the mechanization and automation of the machining process under any production conditions and the ecological cleanliness, which is due to the harmlessness and low toxicity of the electrolytes to be used. When processing workpieces, a high surface quality and a high surface gloss, deburring, a quality-appropriate preparation of the surface for the application of various types of coatings, removal of practically all types of impurities, preserving grease, rust, sinter, lacquer and color coatings are guaranteed.

Brief description of the drawings

The present invention is explained in more detail below on the basis of specific exemplary embodiments and the accompanying drawings. Show it:

Fig. 1 - a diagram for the dependence of the voltage magnitude supplied to the workpiece to be machined and the temperature of the aqueous electrolyte solution at their different concentration from one another according to the invention;

Fig. 2 - graphs of the dependency of the roughness and the reflectivity of the workpiece surface after machining and the voltage applied to the workpiece to be machined, according to the invention.

Best implementation variants of the invention

The present method for the electrochemical machining of workpieces made of electrically conductive materials consists in supplying the workpiece to be machined with a voltage of positive polarity of 200 to 400 V and this in an aqueous electrolyte solution with a concentration of 2 to 12 mass% at a temperature of 40 is immersed up to 95 ° C.

Such electrochemical machining of workpieces made of electrically conductive materials is characterized in that a stable vapor-gas envelope is formed on the surface of the workpiece to be machined, which separates the workpiece surface from the electrolyte and promotes the course of intensive chemical and electrochemical reactions between the material of the workpiece serving as the anode and the electrolyte vapors. This leads to anodic oxidation of the metal surface of the workpiece with simultaneous chemical etching of the oxide that forms. If the oxidation and etching speeds are the same, a polishing effect arises, which consists in an increase in the reflectivity and in a reduction in the roughness of the machined surface. The maximum reflectivity is achieved with the smallest oxide layer, which is sufficient to eliminate the caustic effect of the electrolyte vapors.

The etching mainly takes place on the micro unevenness, where a thinner oxide layer forms. As a result of an increased strength of the electrical field in the space between the workpiece-vapor-gas envelope and the electrolyte, the tips of the surface relief combs are rounded off, which leads to a reduction in the surface roughness of the workpiece to be machined.

The reflectivity and the roughness of the machined surface are therefore dependent on the magnitude of the voltage applied, the concentration and the chemical composition of the electrolyte to be used.

The method according to the invention is explained in more detail with the aid of concrete implementation examples.

example 1

Flat workpieces with dimensions of 20x30x2 mm were machined, which were made of corrosion-resistant steel, containing 0.1% C` 18% Cr, 10% Ni, 1% Ti, rest - Fe. The processing time of the workpiece samples was 2 minutes. The original surface had a roughness of R _a = 0.65 to 0.68 µm and a reflectivity of 35 to 38% (based on the silver level).

The processing conditions for the workpiece samples were selected in the following areas: Operating voltage 240 to 320 V, electrolyte temperature - 40 to 80 ° C, electrolyte composition - 2 to 6% aqueous ammonium sulfate solution. The upper operating limits have been chosen based on the following considerations.

The use of the ammonium sulfate solutions of a higher concentration leads to a significant reduction in the processing quality. The limit of the concentration of the solution at which a polishing effect can still be seen is 6 to 7%. At a higher concentration, the etching of metal begins to dominate, which leads to the disappearance of the gloss. Heating the electrolyte with a concentration of 2 to 6% ammonium sulfate to a temperature of over 80 to 85 ° C also leads to a reduction in the processing quality due to the formation of punctiform depressions, which is caused by an increased chemical activity of the electrolyte at these temperatures. The use of a voltage of more than 320 to 330 V leads to an increase in the roughness of the machined surface as a result of the formation of microcavities which result from an electrical breakdown of the gap between the workpiece-electrode-electrolyte. Increasing the voltage also leads to an increase in the absorption power. Thus, the polishing process by upper limit values of the machining conditions, u. e.g. Voltage of 320 V electrolyte temperature of 80 ° C, electrolyte concentration of 6%, limited.

The choice of the lower limit values of the processing conditions was made with regard to an experimentally obtained averaged diagram for the dependence of the size U (FIG. 1) of the voltage and the temperature t of the electrolyte from one another at different concentrations C of the electrolyte. In this diagram, areas that lie to the right and above the concentration line for the electrolyte correspond to the existence of a stable vapor-gas envelope and consequently a normal course of the process. When choosing a working point below and to the left of the curve, which corresponds to the concentration C, the shell is torn off and a Transition to the switching state of the electrolytic processing is noted. The electrolyte periodically comes into contact with the workpiece surface. A usual electrochemical dissolution of the metal takes place at the contact points, which leads to a strong reduction in the reflectivity and to an increase in the roughness of the surface. Since the size of the power requirement significantly exceeds the size of the power requirement in a stable process, this results in a large increase in the input power and a reduction in the economy of the processing. Therefore, a switching state when polishing is extremely undesirable. In consideration of the upper limit values of the machining conditions during polishing given earlier, the working area on the diagram occupies a zone which is limited by the lines AB for voltage U, BD - for temperature t of the electrolyte, DA - for concentration C of the electrolyte. It can be seen from the diagram that a decrease in the concentration C of the electrolyte leads to an increase in the minimum values of the voltage U and the temperature t of the electrolyte, at which a stable operating state is possible. At a concentration C of the electrolyte of 2%, the temperature t and the voltage U are close to the limit values, which makes the use of low concentration C of the electrolyte inappropriate.

Table 1 shows the results of machining workpieces using the method according to the invention. The graphs of the dependence of the roughness and the reflectivity γ on the applied voltage are shown in FIG. 2, where curve 1 shows the change in roughness R _a , curve 2 - the change in reflectivity γ when machining the workpieces according to the method according to the invention represent. As can be seen from the diagrams, the method according to the invention achieves an extreme in a range of voltage values from 300 to 320 V. The roughness number R _{a is} 0.16 to 0`12) µm (curve 1). A similar picture wins one also considers the second most important characteristic value, the reflectivity γ, which can be 93 to 95% according to the method according to the invention, which is demonstrated by the course of curve 2.

Example 2

Compound metal products, namely workpieces for the production of dental prostheses, which were made from corrosion-resistant steels, were processed. The pressed prosthesis parts were made of steel, which contains 0.12% C, 0.18% Cr, 9% Ni, <1% Ti., Rest - Fe, and the intermediate part - made of cast steel, which contains 0.2% C, Contains 18% Cr, 9% Ni, 2% Si, rest - Fe.

The original surface of the workpiece samples had a roughness of R _a = 0.7 to 0`73 µm and a reflectivity of γ = 36 to 38% (based on the silver level). The processing time was 2 minutes. The processing conditions for the assembled metal products were selected in the following areas: the voltage supplied to the workpiece to be machined - 330 to 380 V, electrolyte temperature - 70 to 90 ° C; a 1 to 10% potassium sulfate solution was used as the electrolyte.

The known technology for polishing composite workpieces provides mechanical or electrolytic processing with different operating states for the voltage, the temperature and the composition of the electrolyte depending on the types of steel used in the construction of the workpiece. The technology according to the invention makes it possible to process a composite (bimetallic) workpiece under uniform technological conditions which increase the reflectivity.

The use of an aqueous potassium sulfate solution as the electrolyte makes it possible to achieve a polishing effect when machining workpieces made of chromium-nickel-silicon steel. The choice of the operating voltage, which is in a range from 330 to 380 V, is due to the fact that when the voltage is reduced to 300 to 315 V, the stability of the vapor-gas envelope is reduced, and the envelope is torn off. the process goes into a switching state, which is accompanied by violent jumps in current. The quality of processing deteriorates and the absorption power increases significant. An increase in the voltage to 385 to 400 V leads to an impairment of the reflectivity γ and the roughness R _a , because traces of the electrical breakdown of the gap between the workpiece-electrode-electrolyte occur on the metal surface.

Lowering the electrolyte concentration to a value below 1% leads to a reduction in the processing power, so that it becomes necessary to apply a higher voltage as a result of a reduction in the electrical conductivity of the solution. When the electrolyte concentration is increased to a value of more than 1%, dominance the etching of metal, which leads to a strong impairment of the reflectivity.

The temperature range in which the present machining process is carried out with optimal parameters is 70 to 90 ° C. At a temperature below 70 ° C, the stability of the steam-gas envelope is reduced, the process proceeds with significant current and voltage fluctuations; at a temperature of over 90 ° C, the processing quality deteriorates due to the increase in the chemical activity of the electrolyte and the disturbance in the thermal balance of the workpiece-vapor-gas-shell-electrolyte system.

The results of the processing are summarized in Table 2. As can be seen from the information in Table 2, the machining method according to the invention allows a minimum value of the surface roughness of the workpiece parts which are made from both types of steel to be achieved, which is in a range from R _a = 0.08 to 0.09 µm , wherein the reflectivity γ is 93 to 95%.

Example 3

Winding wires made of copper with a diameter of Ø = O, 4 µm and = 1.0 µm were processed, which had been insulated with polyester and polyvinyl acetate enamel varnish. The processing was carried out to remove insulating varnish and to clean the wire surface. The processing was carried out in the following areas of operating conditions: operating voltage - 220 to 210 V, electrolyte temperature - 40 to 50 ° C, electrolyte - an 8 to 12% aqueous sodium hydroxide solution.

The implementation of the method according to the invention is based on the use of an electrohydrodynamic operating state of the electrolytic processing.

The present operating state is characterized in that there is no heating of the workpiece, which makes soldering the copper wire difficult and requires additional operations to be carried out to remove the oxide, which was surrounded by a stable vapor-gas envelope. As a result of a high strength of the electric field and a high temperature, the casing has a chemically active medium which reacts with the surface of the workpiece to be machined. A combined action of the chemically active medium of the steam-gas envelope and the high temperature, which rises at the electrically penetrated points of the envelope, leads to a burn-off of the paint insulation while simultaneously cleaning the surface of the remnants of the coating.

The procedure is as follows.

The turn covered with enamel coating insulation is immersed in a solution at a depth equal to the length of the turn end to be cleaned. A positive voltage of 200 to 210 V is supplied to the non-immersed wire part. A steam-gas envelope forms on the lower forehead of the immersed wire part, which is stripped after being cut off. As a result of a high temperature which arises in the breakdown channels penetrating the sheath, the insulation on the wire surface burns off. Because that part of the surface, at the dom the insulation is charred, becomes electrically conductive, a shell also forms on this surface part. The remnants of the burned-off insulation are removed and the wire surface cleaned so that it becomes practically clean. A particularly active destruction of the enamel coating takes place at the border between the already cleaned wire part and the wire part covered with the insulation. This zone of active removal of the coating propagates from the bottom up to the level of the solution.

The selection of the operating voltage, which is in a range from 200 to 210 V, is due to the fact that the stability of the vapor-gas envelope is reduced when the voltage is reduced to 188 to 195 V. This leads to instability in the operating state and a sharp reduction in cleaning performance. Increasing the voltage to 220 to 230 V and more increases the thickness of the vapor-gas envelope and reduces the output due to a reduction in the pulse current that strikes through the vapor-gas envelope.

The use of an aqueous Na0H solution as a chemically active solution is due to the fact that this solution has good electrical conductivity, with no heating of the wire anode at a voltage of 200 to 210 V; it also has a high chemical activity towards the remnants of the coating and a basic character that eliminates the corrosion of the wire after cleaning. A reduction in the concentration of the solution to a value below 8% leads to a reduction in the cleaning performance due to a low chemical activity of the solution. Increasing the concentration to over 12% causes an increase in consumption and causes the solution to spatter heavily during the process, worsening working conditions and not increasing the cleaning speed. The use of a temperature range of 40 to 50 ° C is due to the fact that the temperature of the solution is reduced to a value from below 40 ° C causes the vapor-gas envelope to tear off and to switch to the switching state, while an increase in the temperature to a value of more than 50 ° C leads to an increase in the thickness of the vapor-gas envelope and consequently to a decrease cleaning performance.

The minimum cleaning time for cleaning the above-mentioned wires by the method according to the invention was: with a wire diameter of 0.4 µm - 8 s, a wire diameter of 1.0 µm - 28 s, a wire diameter of 0.4 µm - 16 s, a wire diameter of 1.0 µm - 36 s.

The method according to the invention thus makes it possible, when removing enamel coating insulation from the copper winding wires, to increase the processing power by 2 to 4 times, to exclude manual work, to avoid the use of expensive and toxic chemical reagents, and to improve the working conditions.

Example 4

Flat plates measuring 20x30x1 mm, which had been produced from an alloy containing 62% copper and 38% zinc, and copper plates were processed. The processing time was 60 s. The original surface had a roughness of R _a = 0.55 to 0.6 µm. The reflectivity γ relative to the silver level was 32 to 35%. The processing conditions were selected in the following areas; Operating voltage - 220 to 400 V, electrolyte temperature - 40 to 90 ° C, the electrolyte had the following composition: 0.5 to 8 mass% potassium aluminum alum / or 0.5 to 6 mass% disubstituted ammonium citrate = 0.5 to 3% Na₂C0₃ or 0 , 5 to 6 mass% sodium salt of ethylenediaminetetraacetic acid.

The choice of the lower limit value of the voltage is due to the fact that at voltages of less than 220 V, the steam-gas envelope surrounding the workpiece pattern is torn off, which is an essential prerequisite for the polishing sequence in the electrodynamic operating state. The machining process is characterized by a significant increase in power consumption and one Deterioration of the polishing effect accompanies, it being possible for the machining process to cease, with the formation of thin dark-colored layers (films) on the surface of the workpiece pattern. An increase in the voltage to a value of over 400 V leads to an impairment of the gloss due to the formation of traces of an electrical breakdown in the gap between the workpiece sample electrolyte and the metal surface.

Lowering the concentration of the solutions mentioned to a value of less than 0.5% does not make it possible to bring about a stable electrodynamic process in the entire range of voltages (220 to 400 V), which leads to a reduction in the processing power. Increasing the concentration of the electrolytes to a value exceeding the above-mentioned upper limit values leads to the dominance of the etching of metal, which is reflected in a deterioration in the quality of the polishing.

If the temperature of the solution is below 40 ° C., the stability of the vapor-gas envelope is reduced, which leads to a prevention of the machining process. An increase in the temperature to a value above 90 ° C is accompanied by a deterioration in the processing quality due to an increase in the chemical activity of the electrolyte and by intensive water evaporation, which lead to a change in the solution concentration.

As a result of using the above-mentioned processing conditions, a roughness of R _a = 0.55 was achieved, the reflectivity γ, based on the silver level, being 95 to 97%.

Thus, processing according to the method according to the invention makes it possible to achieve a high quality of polishing, the processing time being reduced by 3 times and the concentration of the electrolytes being reduced by 8 to 10 times.

Example 5

There were flat workpieces with dimensions of 20x20x1 mm made of low-carbon steel with a carbon content processed by 0.08%. The processing time was 3 minutes. The original surface had a roughness of R _a = 1.2 µm. The reflectivity γ was 33 to 35% (based on the silver level).

The processing conditions were selected for the processing of the workpiece samples in the following areas: operating voltage - 240 to 380 V, electrolyte temperature - 81 to 95 ° C, electrolyte composition - 0.5 to 8% of an aqueous ammonium chloride solution. The choice of machining conditions limits is based on the following considerations.

As the investigations showed, an increase in the voltage to a value of over 380 to 390 V leads to an increase in the roughness R _a as a result of an increased electrical erosion which arises during the electrical breakdown in the gap between the workpiece sample electrolyte. At a voltage of less than 230 to 240 V, the stability of the steam-gas envelope surrounding the workpiece pattern is disturbed, the process being unstable and accompanied by large jumps in the current values. This causes a strong increase in the absorption power while simultaneously reducing the reflectivity γ and increasing the roughness R _{a of} the surface of the workpiece to be buried. At a temperature below 75 to 80 ° C there is a deterioration in the stability of the process, which cannot be restored by increasing the voltage up to a voltage level of 380 to 390 V.

At a temperature of the electrolyte of over 95 ° C, the processing quality deteriorates due to an increase in the chemical activity of the electrolyte.

The results of the tests carried out are summarized in Table 3.

Example 6

To increase the operating time of the electrolyte, which consists of an aqueous ammonium chloride solution, 0.5 to 3% by mass of ammonium thiocyanate are added to it. As the tests showed, the operating time is extended by a factor of 1.5 or more. Comparative tests were carried out to determine the operating time of the electrolyte to be used. The processing of a batch of workpiece samples in an amount of 50 pieces with a total processing time of 150 minutes gave stable indicators of the roughness R _{a of} the surface. With an increase in the number of workpiece to be machined pattern of 50 to 100 pieces was recorded deterioration of roughness _Ra. The tests were carried out in the same volume of electrolyte.

With a concentration of the electrolyte prepared on the basis of NH₄Cl of 3% and at voltages of 320-260-240 V, e.g. B., the roughness R _a bes to the values of 0.25-0.23-0.32 µm. When adding NH₄CNS in an amount of 1.5%, an increase in the roughness R _{a was} observed when machining a batch of workpiece samples in a number of 100 pieces. In this way, the introduction of an additive into the electrolyte increases its operating time by a factor of two, the value of the reflectivity γ and the roughness R _{a of} the machined workpieces not deteriorating. Table 4 shows the results of the tests of a two-component solution, using ammonium thiocyanate NH₄CNS as an additive. With a concentration of the additive of less than 0.5%, this practically does not affect the operating time. While increasing the additional concentration to a value of over 3% leads to the formation of a black film on the workpiece sample surface. At other ratios of the components NH₄Cl and NH₄CNS to each other, the tests gave similar results, uz the reflectivity γ and the roughness R _a do not deteriorate during the operating time of the Electrolyte with an additive is extended by 1.5 to 2 times.

Example 7

Flat plates measuring 20x30x2 mm were machined, which had been made of aluminum. The processing time was 1 minute. The original roughness R _a = 1.03 µm. The reflectivity γ was 35%, based on the silver level.

The processing conditions were selected in the following areas: operating voltage - 260 to 400 V, electrolyte temperature - 70 to 90 ° C, electrolyte composition - 0.5 to 5 mass% iron (III) chloride.

By using iron (III) chloride when machining aluminum in an electrohydrodynamic operating state, the reflectivity γ of the surface to be machined can be increased and its roughness R _{a can be} reduced. The limit value of the solution concentration at which the polishing can still be observed is 3%. At a higher concentration, the etching of metal begins to dominate, which makes the shine disappear. Heating the electrolyte with a concentration of 0.5 to 3% to a temperature of over 90 ° C also leads to a deterioration in the processing quality as a result the formation of punctiform depressions, which are caused by an increased chemical activity of the electrolyte at these temperatures. At a voltage of over 400 V, the roughness R _{a of} the surface to be machined increases, because during the electrical breakdown, the active piece-electrolyte micro-hollows form in the interspace.

The use of an electrolyte concentration of less than 0.5% leads to an increase in the minimum values of the voltages and the electrolyte temperature, at which a stable process can be carried out. At a concentration of less than 0.5% and a temperature of less than 60 ° C there is a transition to the switching state of the electrolytic processing. The electrolyte periodically comes into contact with the workpiece surface. A strong electrochemical anodic metal dissolution takes place at the contact points, which leads to a reduction in the reflectivity γ and to an increase in the roughness R _a .

As a result of the processing for the roughness R _a was reduced to 0.30 microns, while the reflectance γ a level of 73% achieved.

Industrial applicability

The invention can be used in mechanical engineering technologies for finishing products and preparing workpieces for applying coatings by electroplating; Vacuum, ion plasma vapor deposition are used.

Claims (10)

Process for the electrochemical machining of parts made of electrically conductive materials, which consists in supplying a voltage of positive polarity to the workpiece to be machined and immersing it in a heated aqueous electrolyte solution, characterized in that the workpiece to be machined has a voltage of 200 to 400 V is supplied while the temperature of the aqueous electrolytic solution having a concentration of 2 to 12 mass% is 40 to 95 ° C. Method for electrochemical processing of workpieces made of electrically conductive materials according to claim 1, characterized in that the workpiece to be machined is supplied with a voltage of 240 to 320 V and an aqueous ammonium sulfate solution with a concentration of 2 to 6% by mass at a temperature of 40 to 80 ° C is used as an aqueous electrolyte solution. Method for electrochemical processing of workpieces made of electrically conductive materials according to claim 1, characterized in that the workpiece to be machined is supplied with a voltage of 330 to 380 V and an aqueous potassium sulfate solution with a concentration of 1 to 10% by mass at a temperature of 70 to 90 ° C is used as an aqueous electrolyte solution. Method for electrochemical processing of workpieces made of electrically conductive materials according to claim 1, characterized in that the workpiece to be machined is supplied with a voltage of 200 to 210 V and an aqueous sodium hydroxide solution with a concentration of 8 to 12% by mass at a temperature of 40 to 50 ° C is used as an aqueous electrolyte solution. Process for electrochemical machining of workpieces made of electrically conductive materials according to claim 1 , characterized in that the workpiece to be machined is supplied with a voltage of 220 to 400 V and an aqueous potassium aluminum alum with a concentration of 0.5 to 8% by mass is used as an aqueous electrolyte solution at a temperature of 40 to 90 ° C. Process for the electrochemical processing of workpieces made of electrically conductive materials according to claim 1, characterized in that the workpiece to be machined is supplied with a voltage of 220 to 240 V and an aqueous solution of disubstituted ammonium citrate with a concentration of 0.5 to 6 mass% with addition of sodium carbonate with a concentration of 0.5 to 3% by mass at a temperature of 40 to 90 ° C is used as an aqueous electrolyte solution. Process for the electrochemical machining of workpieces made of electrically conductive materials according to claim 1, characterized in that the workpiece to be machined is supplied with a voltage of 220 to 400 V and an aqueous solution of sodium salt of ethylenediaminetetraacetic acid with a concentration of 0.5 to 6% by mass a temperature of 40 to 90 ° C is used as an aqueous electrolyte solution. Method for the electrochemical machining of workpieces made of electrically conductive materials according to claim 1, characterized in that the workpiece to be machined is supplied with a voltage of 240 to 380 V and an aqueous ammonium chloride solution with a concentration of 0.5 to 8% by mass at a temperature of 81 up to 95 ° C is used as an aqueous electrolyte solution. Process for the electrochemical processing of workpieces made of electrically conductive materials n according to Claim 8, characterized in that ammonium thiocyanate with a concentration of 0.5 to 3% by mass is additionally introduced into the aqueous electrolyte solution. Method for electrochemical processing of workpieces made of electrically conductive materials according to claim 1, characterized in that the workpiece to be machined is supplied with a voltage of 260 to 400 V: and an aqueous solution of iron (III) chloride with a concentration of 0.5 to 3 mass% is used at a temperature of 70 to 90 ° C as an aqueous electrolyte solution.

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