KR20190042231A - Plasma Electrolytic Polishing Method with Luster and Dimensional Stability - Google Patents

Abstract

The present invention relates to a method to perform a plasma electrolytic polishing with luster and dimensional stability. More specifically, according to an embodiment of the present invention, the method comprises: a step of preparing a subject; a step of installing an anode and a cathode in an electrolyte and connecting the subject to the anode; a step of applying a voltage to the anode and the cathode and generating a first plasma; a step of performing an electrolytic polishing on the subject with the first plasma; a step of applying a voltage lower than the voltage applied in the step of generating the first plasma and generating a second plasma; and a step of performing electrolytic polishing on the subject with the second plasma. The step of performing the electrolytic polishing with the first plasma is conducted in an area with a high voltage of 380V or higher. The step of performing the electrolytic polishing with the second plasma is conducted in an area with a low voltage of 370V or lower. According to the present invention, the method retains dimensional stability without material loss.

Description

TECHNICAL FIELD [0001] The present invention relates to a plasma electrolytic polishing method and, more particularly,

The present invention relates to a plasma electrolytic polishing method capable of luster and dimensional stability, and more particularly, to a technique of providing a plasma electrolytic polishing method in two stages by a method of maintaining a surface gloss and a dimension of a product to be obtained will be.

Most metal products are fabricated into final product shapes through machining, welding and forming processes, including heat treatment. After the shape is completed, the metal surface is modified to the desired surface properties through various surface treatment methods such as painting and plating depending on the purpose. Polishing is often applied to the appearance of metal products, or to apply additional surface treatments such as plating. Generally, the most widely used polishing method is electrolytic polishing, which is an electrochemical method to make the surface smooth with a surface gloss.

Electro polishing is the reverse process of plating. In recent years, demand for precision and cleanliness of materials has been required due to the development of required industry requiring cleanliness such as semiconductor business. In order to achieve this, Electrolytic polishing, which is a new non-contact polishing method that is out of the processing method, is required. In the conventional mechanical machining method, there is a trace of machining on the surface of the workpiece, so that a clean surface can not be obtained immediately.

Generally, electrolytic polishing is performed by using a metal product dissolved in an electrolytic solution as an anode and a metal insoluble in an electrolytic solution as a cathode and by applying a voltage between the anode and the cathode, It is a method of polishing (oxidation) the surface of metal products by melting. In order to polish a metal product by electrolytic polishing, an electrolytic solution is filled in an electrolytic bath, a product to be polished is set as an anode, a negative electrode not dissolving in the electrolytic solution is provided, and then a DC or pulse waveform Apply power. In electrolytic polishing, when an electric current is applied even under the condition that the metal product is not easily dissolved in the electrolytic solution, the metal product is forcibly dissolved little by little. When electrolytic polishing proceeds, the convex portion concentrates more current than the concave portion, so that the dissolution occurs more quickly and eventually the entire surface of the product is smoothed.

As described above, by selectively dissolving the minute portion of the metal surface, the surface of the metal product can be flattened (polished) according to the purpose, and the effect of improving the gloss, appearance, reflection force and corrosion resistance, .

However, the electrolytic polishing method causes a lot of damage to the material to be polished in order to realize the intended surface smoothness. In this case, the surface state can be obtained at a desired level, but due to the loss of material during polishing, it is possible to cause defects by causing changes in the dimensions and shape of the processed product.

Another problem is that electrolytic polishing uses a chemical that is toxic to the polishing liquid (electrolytic solution) used for smooth polishing. For example, the electrolytic drug most commonly used in polishing is a need for phosphoric acid (H ₃ PO ₄₎ the number of water washing because of the properties of a viscous due not only stability to toxicity during work operations and This also increases the waste water amount.

Therefore, a plasma electrolytic polishing technique has been studied as a polishing method that solves these problems, maintains dimensional stability due to material loss, and maintains surface gloss. Plasma electrolytic polishing is the most significant difference from conventional electrolytic polishing. In the case of electrolytic polishing, a voltage within 50V is generally applied. In the case of plasma electrolytic polishing, a high voltage of at least 250V is applied in the electrolytic polishing. Thereby generating a plasma.

JP-A-2016-037622 A

Disclosure of the Invention The present invention provides an effect of maintaining the dimensional stability without loss of materials by using a two-stage plasma electrolytic polishing method in order to solve the problem of material loss when the surface of a metal product is modified by electrolytic polishing will be.

More specifically, a plasma electrolytic polishing method is used for electrolytic polishing of a metal, and the electrolytic polishing is performed in two stages with different voltage ranges.

The two-stage plasma electrolytic polishing of the present invention ensures dimensional stability and simultaneously reduces the surface roughness and glossiness of the surface.

In addition, in the case of conventional electrolytic polishing, a problem of environmental pollution is solved by using a polishing liquid which does not contain chemical toxicity by using a polishing liquid which is toxic.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. There will be.

According to an aspect of the present invention, there is provided a plasma electrolytic polishing method. The plasma electrolytic polishing method includes the steps of preparing a target object, providing an anode and a cathode in an electrolytic solution, connecting a target to an anode, connecting the anode and the cathode, Generating a second plasma by applying a voltage lower than a voltage applied in the step of generating the first plasma, a step of generating a first plasma by applying a voltage to the first plasma, And a step of electrolytically polishing the object with the second plasma, wherein the step of performing the first plasma electrolytic polishing treatment is performed in a high voltage region of 380 V or higher, and the step of performing the second plasma electrolytic polishing treatment is a step of And is performed in a low voltage region.

Further, the object to be treated is characterized by containing stainless steel, Ni alloy, Cu alloy or Co-Cr alloy.

The electrolytic solution is characterized by containing ammonium sulfate, potassium hydroxide or sodium hydroxide.

The electrolytic solution has a pH of 4 to 8.

The electrolytic solution has a molar concentration of 0.01M to 1M.

Also, the temperature of the electrolytic solution is 20 ° C to 90 ° C.

Further, the high voltage region of the first plasma electrolytic polishing is characterized by being 380 V to 500 V.

In addition, the step of generating the first plasma may be performed for 20 seconds to 10 minutes.

The low-voltage region of the second plasma electrolytic polishing is characterized by having a voltage of 260 V to 370 V.

Also, the step of generating the second plasma may be performed for 20 seconds to 5 minutes.

According to another aspect of the present invention, there is provided a metal material produced by electrolytic polishing using the above-described plasma electrolytic polishing method.

According to the embodiment of the present invention, an electrolytic solution having no toxicity and viscosity can be used to solve the problem of generation of wastewater in the flushing operation due to stability and viscosity from toxicity and to improve the environmental pollution.

Further, plasma electrolytic polishing composed of two stages can achieve the effect of simultaneously providing the luster and dimensional stability of the metallic material.

Further, the surface of the metal material through the plasma electrolytic polishing can obtain an effect of high adhesion.

Further, an effect of providing the corrosion resistance, heat resistance and wear resistance of the surface of the metal material through plasma electrolytic polishing can be obtained.

In addition, it is possible to obtain an effect of reducing surface loss by removing hydrogen which induces bacterial growth on the surface of the metal material through plasma electrolytic polishing.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a flowchart of a plasma electrolytic polishing method.
FIG. 2 is a graph showing the degree of loss of a raw material during electrolytic polishing and plasma electrolytic polishing. FIG.
3 is a graph showing a range of voltage values applied in electrolytic polishing and plasma electrolytic polishing.
Fig. 4 is a photograph showing the dimensional deformation caused by plasma electrolytic polishing in the low voltage region.
5 is a photograph showing the degree of surface gloss obtained in plasma electrolytic polishing at a high voltage region.
6 is a photograph showing the product quality obtained by applying the two-stage plasma electrolytic polishing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" (connected, connected, coupled) with another part, it is not only the case where it is "directly connected" "Is included. Also, when an element is referred to as " comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating a plasma electrolytic polishing method according to an embodiment of the present invention.

Referring to FIG. 1, in an embodiment of the present invention, a plasma electrolytic polishing method includes preparing a target object (S100), providing an anode and a cathode in an electrolyte, (S300) of applying a voltage to the anode and the cathode to generate a first plasma (S300); electrolytically polishing (S400) the object with the first plasma; A step (S500) of generating a second plasma by applying a voltage lower than a voltage applied in the step of generating the first plasma, and a step (S600) of electrolytically polishing the object with the second plasma, The first plasma electrolytic polishing process is performed in a high voltage region of 380 V or higher and the second plasma electrolytic polishing process is performed in a low voltage region of 370 V or lower.

First, a target object is prepared (S100).

For example, the object may comprise stainless steel, a Ni alloy, a Cu alloy, or a Co-Cr alloy. However, the present invention is not limited thereto.

In addition, if the object is not easily dissolved in the electrolytic solution and current is applied, the object may be forcibly dissolving little by little.

Next, an anode and a cathode are provided in the electrolyte, and the object is connected to the anode (S200).

The electrolytic solution may be characterized by containing ammonium sulfate, potassium hydroxide or sodium hydroxide.

The pH of the electrolytic solution may be 4 to 8.

As compared with an electrolyte used in conventional electrolytic polishing, the electrolytic solution can contain only a small amount of salt in order to improve the conductivity of the electrolytic water and the stability of the generated plasma, so that an electrolytic solution of an environmentally friendly component can be constituted.

In addition, there is a problem in that a toxic and viscous electrolytic solution is conventionally used, and a large amount of liquid is deposited on articles manufactured through electrolytic polishing, and a large amount of pollutants such as chromic acid, sulfuric acid, and phosphoric acid flows into the wastewater treatment plant, Can provide a remarkably high disadvantage and an effect of solving the environmental pollution problem.

Also, by using an electrolyte having an acidity range and a neutral range, it is possible to shorten the post-treatment process that occurs when acidity or basicity is used.

The molar concentration of the electrolytic solution may be 0.01M to 1M.

When the molar concentration of the electrolytic solution is less than 0.01M, the electrolytic solution serving as conductivity loses its role, thereby increasing the threshold voltage and discharging. When the concentration exceeds 1M, large and deep pores are formed on the surface of the object, And corrosion resistance is deteriorated.

Also, the temperature of the electrolytic solution may be 20 ° C to 90 ° C.

When the temperature of the electrolytic solution is less than 20 ° C, the reaction rate is lowered and the electrolytic polishing reaction can be suppressed. When the temperature exceeds 90 ° C, water starts to boil and plasma generation becomes unstable. Therefore, it may be appropriate to maintain the temperature of the electrolyte at 20 캜 to 90 캜.

Further, the object is connected to the anode, and a metal insoluble in the electrolyte is connected to the cathode.

The subject is connected to the anode and electrolyzed at the surface of the subject to be polished.

Next, a voltage is applied to the anode and the cathode to generate a first plasma (S300).

When the first plasma is generated, the current is concentrated more than the concave portion of the convex portion, so that the dissolution occurs more quickly, so that the surface of the object becomes smooth as a whole, a desired roughness can be obtained, and dimensional stability can be enhanced.

And the high voltage region of the first plasma electrolytic polishing is 380 to 500V.

In the high voltage region of 380 V to 500 V of the first plasma electrolytic polishing, the plasma will be uniformly formed, and thus the surface roughness is lowered by the formed plasma, so that the roughness can be reduced while maintaining dimensional stability.

Then, the object to be polished is electrolytically polished with the first plasma (S400).

The step of generating the first plasma may be performed for 20 seconds to 10 minutes.

If the time for generating the first plasma is less than 20 seconds, the surface roughness of the object can not be sufficiently lowered. If the time is longer than 10 minutes, the dimensional change of the object is severe and the surface roughness is increased again do.

Next, a voltage lower than the voltage applied in the first plasma generating step is applied to generate a second plasma (S500).

And the low voltage region of the second plasma electrolytic polishing is 260V to 370V.

The electrolytic polishing treatment with the first plasma can reduce the roughness while maintaining the dimensional stability, but has a problem that the polishing effect is inferior.

On the other hand, in the case of the second plasma generated in the low voltage region of 260 V to 370 V, relatively less effect is generated than the first plasma, so that the effect of dissolving the surface of the object by the electrolytic solution to exhibit luster is relatively It is bigger.

Therefore, there is an advantage that the second plasma treatment, which will be described later, can simultaneously obtain a gloss effect while lowering the illuminance while maintaining dimensional stability by the first plasma treatment.

In the conventional electrolytic polishing technique, the voltage is applied within 50 V, but in the case of plasma electrolytic polishing, the minimum voltage required for plasma formation is 250 V, so plasma electrolytic polishing may not occur at a voltage lower than 250 V.

Then, the object to be polished is electrolytically polished with the second plasma (S600).

And the step of generating the second plasma may be performed for 20 seconds to 5 minutes.

 If the time for generating the second plasma is less than 20 seconds, the surface roughness of the object can not be sufficiently lowered. If it exceeds 5 minutes, the dimensional change of the subject is severe and the surface roughness is increased again do.

Since the second plasma is generated in a low voltage range of 260V to 370V and is generated relatively less than the first plasma, the effect of reducing the illuminance and melting the surface of the object by the electrolytic solution is relatively more effective Big.

Therefore, when the two-stage plasma electrolytic polishing method of the present invention including the first plasma electrolytic polishing step (S400) and the second plasma electrolytic polishing step (S600) of the present invention is used, the first plasma electrolytic polishing step The stability is maintained and the illuminance is reduced and the object is polished through the second plasma electrolytic polishing step, whereby the surface roughness can be reduced, the dimensional stability can be maintained, and the glossiness effect of assertion can be obtained at the same time.

Also, performing the two-stage plasma electrolytic polishing of the present invention through the reaction time range of 20 seconds to 10 minutes of the first plasma electrolytic polishing step (S400) and 20 seconds to 5 minutes of the second plasma electrolytic polishing step (S600) Shows that the shape of the film and the thickness of the film are proportional to the time during which plasma electrolytic polishing is carried out and that all aspects such as surface roughness, surface hardness, abrasion resistance, and corrosion resistance are affected by adhesion.

In addition, the hydrogen on the surface of the object can be removed through the two-stage plasma electrolytic polishing of the present invention to reduce the surface loss due to the bacteria.

Therefore, by the effect of the two-stage plasma electrolytic polishing, it is possible to reduce the surface loss due to the bacteria by removing the hydrogen which induces the maintenance of the dimensional stability, the reduction in the luminance, the gloss, the adhesion, the corrosion resistance, the heat resistance, the wear resistance and the growth of the metal surface bacteria. Can be obtained.

Manufacturing example

1) The electrolytic bath was filled with 0.1M ammonium sulfate (NH ₄ ) ₂ SO ₄ at 40 ° C temperature.

2) An anode and a cathode were installed in the electrolyte, and a stainless steel was connected to the anode.

3) A voltage of 380 to 500 V was applied to perform the first plasma electrolytic polishing.

4) 260 V to 370 V voltage was applied to perform second plasma electrolytic polishing.

5) Stainless steel with polished surface and dimensional stability was obtained by electrolytic polishing.

FIG. 2 is a graph showing the degree of loss of a raw material during electrolytic polishing and plasma electrolytic polishing. FIG.

Referring to FIG. 2, it can be seen that the conventional electrolytic polishing has a large loss of material in order to realize the smoothness of the surface, while reducing the loss of material and reducing the surface roughness through plasma electrolytic polishing.

3 is a graph showing a range of voltage values applied in electrolytic polishing and plasma electrolytic polishing.

Referring to FIG. 3, in the conventional electrolytic polishing, a voltage is applied within 50 V, but in the case of plasma electrolytic polishing, when a voltage of at least 250 V is applied, plasma is generated in the electrolyte.

Fig. 4 is a photograph showing the dimensional deformation caused by plasma electrolytic polishing in the low voltage region.

Referring to FIG. 4, when plasma electrolytic polishing is performed in the low voltage region of 260 V to 370 V according to the present invention, the effect of polishing the metal surface is greater than the polishing effect of reducing the roughness. Also, it can be seen that it is difficult to maintain dimensional stability due to material loss.

5 is a photograph showing the degree of surface gloss obtained in the plasma electrolytic polishing in the high voltage region.

Referring to FIG. 5, it can be seen that when plasma electrolytic polishing is performed in the high voltage region of 280 V to 500 V of the present invention, desired luminance is obtained in terms of reduction in luminance and dimensional stability and dimensional stability is high, have.

6 is a photograph showing the product quality obtained by applying the two-stage plasma electrolytic polishing.

6, a desired roughness is obtained in the first plasma electrolytic polishing step of the present invention, surface gloss is obtained in the step of performing the second plasma electrolytic polishing, and a surface to be obtained through the two-stage plasma electrolytic polishing of the present invention It is possible to obtain a metal material in which the state (roughness, gloss) and the dimensions of the manufactured product are realized at the same time.

Therefore, comparing FIGS. 4 and 5 with FIG. 6, it can be seen that the surface luster effect of FIG. 6 and the different high dimensional stability effects of FIG. 5 are obtained simultaneously.

According to the embodiment of the present invention, an electrolytic solution having no toxicity and viscosity can be used to solve the problem of generation of wastewater in the flushing operation due to stability and viscosity from toxicity and to improve the environmental pollution.

Further, plasma electrolytic polishing composed of two stages can achieve the effect of simultaneously providing the luster and dimensional stability of the metallic material.

Further, the surface of the metal material through the plasma electrolytic polishing can obtain an effect of high adhesion.

Further, an effect of providing the corrosion resistance, heat resistance and wear resistance of the surface of the metal material through plasma electrolytic polishing can be obtained.

In addition, it is possible to obtain an effect of reducing surface loss by removing hydrogen which induces bacterial growth on the surface of the metal material through plasma electrolytic polishing.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (11)

Preparing a subject;
Providing an anode and a cathode in the electrolyte and connecting the object to the anode;
Generating a first plasma by applying a voltage to the anode and the cathode;
Electrolytically polishing the object with the first plasma;
Generating a second plasma by applying a voltage lower than a voltage applied in the first plasma generating step; And
And subjecting the object to the electrolytic polishing treatment with the second plasma,
Wherein the first plasma electrolytic polishing process is performed in a high voltage region of 380 V or higher and the second plasma electrolytic polishing process is performed in a low voltage region of 370 V or lower. The method according to claim 1,
Wherein the object comprises a stainless steel, a Ni alloy, a Cu alloy, or a Co-Cr alloy. The method according to claim 1,
Wherein the electrolytic solution contains ammonium sulfate, potassium hydroxide or sodium hydroxide. The method according to claim 1,
Wherein the electrolytic solution has a pH of from 4 to 8. The method according to claim 1,
Wherein the molar concentration of the electrolytic solution is 0.01M to 1M. The method according to claim 1,
Wherein the electrolytic solution has a temperature of 20 to 90 占 폚. The method according to claim 1,
Wherein the high-voltage region of the first plasma electrolytic polishing is in a range of 380 to 500V. The method according to claim 1,
Wherein the step of generating the first plasma is performed for 20 seconds to 10 minutes. The method according to claim 1,
And the low voltage region of the second plasma electrolytic polishing is 260V to 370V. The method according to claim 1,
Wherein the step of generating the second plasma is performed for 20 seconds to 5 minutes. A metal material produced by electrolytic polishing by the electrolytic polishing method of claim 1.

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