KR101153547B1 - Method for removing oxide film, method for coating surface of steel sheet and steel sheet having a good adhesiveness - Google Patents

Abstract

The present invention relates to an etching method of an oxide film present on the surface of a steel sheet, in order to secure adhesion between the coating layer and the steel sheet using vacuum deposition, which is performed for the purpose of protecting the surface of the steel sheet, improving durability, and providing designability. In the method of etching an oxide film together with impurities such as moisture present on the surface, an etching condition for setting efficient equipment and process conditions is provided.
One or more chambers and a plasma generating device installed inside the chamber, the oxide film formed on the surface of the steel sheet passing through the chamber by measuring the thickness of the oxide film present on the surface of the steel sheet, and supplying power to generate plasma After etching, the oxide film remaining on the surface of the steel sheet after the etching provides a method of etching the oxide film on the surface of the steel sheet, characterized in that the remaining thickness of 70% or less based on the natural oxide film thickness (excluding 0).

Description

METHOD FOR COATING SURFACE OF STEEL SHEET AND STEEL SHEET HAVING A GOOD ADHESIVENESS}

The present invention relates to an etching method of an oxide film present on the surface of a steel sheet, in order to secure adhesion between the coating layer and the steel sheet using vacuum deposition, which is performed for the purpose of protecting the surface of the steel sheet, improving durability, and providing designability. The present invention provides a method for efficiently etching an oxide film together with impurities such as moisture present on a surface thereof, and from this, to provide an etching condition for setting efficient equipment and process conditions.

In general, the surface of the steel sheet is known to have a natural oxide film of about 10 nm, as shown in Fig. 2 together with impurities and moisture. However, when moisture, impurities, oxide films, etc. are present on the surface of the steel sheet, when the surface coating is performed for various purposes such as protecting the surface of the steel sheet, improving durability, and providing designability, the adhesion between the coating layer and the steel sheet It is reported that such an impurity, oxide film or the like on the surface of the steel sheet must be removed. Therefore, in order to remove such an oxide film etc., the etching process with respect to the steel plate surface is performed.

However, quantitative analysis of how the thickness of the oxide film on the surface of the steel sheet affects the adhesion has hardly progressed, and it is not reported how much oxide film was removed between the steel sheet and the coating layer after etching. Therefore, in the usual case, an etching process for completely removing an oxide film having a thickness of 10 nm is performed.

Therefore, quantitative analysis of the degree of etching of the oxide film, precise analysis of the change in adhesion force and optimization of the etching conditions are required, and various research institutes and companies at home and abroad are required to provide an etching degree that can obtain the optimum adhesion strength. Technological development and research for etch conditions are underway, but they do not provide satisfactory results yet.

Thus, until now, excessive etching has been performed to completely remove the oxide film present on the surface of the steel sheet, which results in a large power consumption and additional equipment required for this purpose. Excessive cost of etching is required, and the life of etching equipment is shortened.

The present invention quantifies the presence and thickness of the oxide film using a high resolution electron microscope and measures the adhesion between the oxide film and the coating layer on the surface of the steel sheet, suggesting the optimum etching conditions for securing the adhesion between the steel plate surface and the coating layer, This minimizes the equipment and process time for etching, thereby enabling economics.

Further, a coating method of forming a coating layer after etching an oxide film by the method of the present invention is provided.

Furthermore, the steel plate excellent in the adhesive force of the coating layer obtained by applying the method of this invention is provided.

The present invention includes one or two or more chambers and a plasma generating apparatus provided inside the chamber, the surface of the steel sheet passing through the chamber by measuring the thickness of the oxide film present on the surface of the steel sheet, and supplying power to generate a plasma The oxide film formed on the substrate is etched, and the oxide film remaining on the surface of the steel sheet after etching has a thickness of 70% or less based on the natural oxide film thickness (excluding 0). Is provided.

Preferably, the oxide film remaining on the surface of the steel sheet after the etching may have a thickness of 7 nm or less (except 0).

Further, the chamber is provided with an oxide film etching method of the surface of the steel sheet, characterized in that it comprises a magnet on the top of the chamber to focus the generated plasma to increase the density of the plasma.

Meanwhile, the thickness of the oxide film may be measured using a high resolution electron microscope and an EDS.

Furthermore, the present invention comprises the steps of etching the oxide film on the surface of the steel sheet as described above; And forming a coating layer on the surface of the steel sheet subjected to the oxide film etching.

In addition, in the present invention, a coating layer is formed on the surface of the steel sheet, an oxide film having a thickness of 70% or less (excluding 0) with respect to the thickness of the natural oxide film between the steel sheet and the coating layer, excellent adhesion of the coating layer Is provided,

In addition, a coating layer is formed on the surface of the steel sheet, and an oxide film having a thickness of 7 nm or less (excluding 0) is present between the steel sheet and the coating layer, the steel sheet excellent in adhesion of the coating layer is provided. .

More preferably, the coating layer formed on the surface of the steel sheet may be a dry coating layer by plasma dry coating.

According to the present invention, by quantifying the presence and thickness of the oxide film according to the etching conditions and by measuring the adhesion between the steel plate surface and the coating layer, it is possible to find the optimum etching conditions for securing the adhesion between the steel plate surface and the coating layer, This results in the best economics by minimizing the installation and processing time of suitable equipment for accurate etching.

Furthermore, according to the present invention, in the case of forming a coating layer on the surface of the steel sheet, despite the presence of some oxide film after etching, a steel sheet having a level of adhesion similar to that of the coating layer adhesion when the coating layer is formed on the steel sheet is completely etched oxide You can get it.

1 is a view schematically showing the concept of an etching chamber to which the method of the present invention is applied.
2 is a view schematically showing a cross section of a general steel sheet including a natural oxide film.
3 is an interface high-resolution transmission electron microscopy (TEM) photograph showing a cross section of a steel plate after Cu is coated without etching.
FIG. 4 is an EDS spectral photograph measured in the oxide layer of FIG. 3.
FIG. 5 is an interface high resolution TEM photograph of a cross section of a conventional steel plate after overetching.
6 is an interface high resolution TEM photograph of a cross section of a steel plate having a 5 nm oxide film after etching.

3 is an electron micrograph showing a cross section of a steel sheet in which Cu is deposited on the surface of the steel sheet 3 not subjected to etching. As shown in FIG. 3, it can be seen that an oxide film 5 of about 10 nm exists between the steel plate 3 and the Cu deposition layer 6. Furthermore, it can be seen from the EDS (Energy Dispersive Spectrometer) data measured at the interface between the steel sheet and the Cu deposition layer 6 that the oxide film 5 exists even in the presence of a large amount of oxygen. However, when such an oxide film 5 is present, a phenomenon occurs in which the deposited Cu deposition layer 6 is easily peeled from the steel sheet 3.

Therefore, the natural oxide film present on the surface of the steel sheet must be removed from the steel sheet. However, the inventors of the present inventors conducted a study and confirmed that even if the oxide film remained on the surface of the steel sheet, the adhesion strength equivalent to that of the steel sheet and the deposition layer when 100% of the natural oxide film was removed was obtained. The conditions for etching the oxide film on the surface of the steel sheet from the relationship between the adhesion and the adhesion force are provided.

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

1 is a view schematically showing a continuous etching apparatus applied in the present invention, having one or more etching chambers, each of which includes an anode box 1. A process gas for generating plasma, such as argon, is introduced into the etching chamber, and power is applied to an anode box, which is an electrode, to generate plasma 2, thereby etching the oxide film from the surface of the steel sheet 3 passing through the chamber. Can be.

In etching the oxide film, when the thickness of the natural oxide film is 100%, an etching rate of 30% or more (except 100% is excluded), that is, an oxide film having a thickness of 70% or less of the thickness of the natural oxide film (where , 0 is excluded.). As described above, even when an oxide film remains on the surface of the steel sheet, when the deposition layer is formed on the surface of the steel sheet, the adhesion between the deposition layer and the steel sheet is equivalent to that of the deposition layer against the surface of the steel sheet on which 100% of the oxide film is etched. It can be confirmed experimentally that has. In general, since the thickness of the natural oxide film present on the steel sheet is about 10 nm, the thickness of the oxide film remaining after the etching process is 7 nm or more (except 0). Preferred at

In the etching process of the present invention, the etching chamber may include one or two or more, in the case of having two or more etching chambers, even if the steel plate 3 is moved at high speed by connecting several in series The oxide film can be etched.

Therefore, in order to obtain a high etching rate, the number of chambers is generally increased. Even though an etching rate of 30%, that is, an oxide film of up to 70% of the thickness of the natural oxide film remains on the surface of the steel sheet, the adhesion between the steel sheet and the deposition layer is 100. Compared with the steel sheet of% etch rate, it provides the same level of adhesion, which simplifies the process equipment that was excessively installed for the conventional overeating. Nevertheless, the adhesion between the steel sheet and the coating layer formed on the surface thereof can be simplified. Adhesion of the degree which can be obtained by overetching is obtained, and it is efficient.

The upper portion of the chamber may include a magnet 4 such as a permanent magnet. The magnet 4 serves to focus the plasma to increase the density of the generated plasma. As the density of the plasma is increased, the etching efficiency of the oxide layer on the surface of the steel sheet may be increased even when lower power is supplied.

According to the present invention, it is possible to prevent over-etching that was performed to remove the oxide film existing on the surface of the steel sheet, and furthermore, the oxide film must be etched 100% to obtain excellent adhesion between the steel sheet surface and the coating layer. It can be seen. That is, according to the present invention, in the etching process of the oxide film, when the thickness of the natural oxide film is 100, when the thickness of the oxide film remains at 70% or less (except 0), the coating layer formed on the surface of the steel sheet Since the adhesion strength is equivalent to that of the conventional steel sheet in which the oxide film is over-etched, appropriate process conditions can be set as necessary in etching the oxide film on the surface of the steel sheet.

Furthermore, by applying the process conditions according to the present invention in such an oxide film etching process, it is possible to simplify the equipment required for the etching process and further reduce the cost required for the process. However, it will be appreciated by those skilled in the art that the amount of power required for etching the oxide film will be increased in the case of high strength steel as compared to the general steel sheet such as cold rolled steel sheet.

After etching the natural oxide film on the surface of the steel sheet by the above method, a coating layer may be formed on the surface of the steel sheet by a conventional method. In this case, the coating layer may be formed by a dry coating method which may be generally applied in the field of the present invention. For example, the coating layer may be formed by a dry coating method using plasma, an electron beam, or heating. The coated steel sheet thus obtained has excellent adhesion between the steel sheet and the coating layer despite the presence of an oxide film on the steel sheet surface.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are shown as an example of the present invention and do not limit the present invention.

[Example]

Comparative Example 1

After coating the Cu (6) layer without performing an etching treatment on the surface of the cold rolled steel sheet having an oxide film of 10 nm, a photograph was taken with a high resolution electron microscope, and this is shown in FIG. 3. As shown in FIG. 3, it can be clearly seen that an oxide film 5 layer of about 10 nm exists between the steel sheet 3 and the Cu coating layer 6. On the other hand, an EDS (Energy Dispersive Spectrometer) measurement was performed on the oxide film 5 layer, and the results are shown in FIG. 4, indicating that a large amount of oxygen exists. It was confirmed that the Cu coating layer 6 deposited under such conditions was easily peeled off from the steel sheet 3 due to the presence of the oxide film 5.

Reference Example 1

As shown in FIG. 1, a continuous etching apparatus consisting of six etching chambers was used. Each chamber has an anode box and a permanent magnet attached to the top of the chamber, injects argon gas into the chamber, applies power to the anode box to generate a plasma, and passes the steel sheet to be etched under the permanent magnet. And to etch the oxide film on the surface.

The thickness of the natural oxide film was measured on the surface of the cold rolled steel sheet to be etched using a high resolution electron microscope, which was 10 nm.

Argon gas was injected into the continuous etching apparatus, and power was supplied to each anode box to generate plasma. At this time, the sum of the applied electric power was 120 kW. The steel sheet was supplied to the etching apparatus at a speed of 200 m / min to perform oxide film etching on the surface of the cold rolled steel sheet.

The Zn-Mg coating layer was deposited on the surface of the etched steel sheet. Zn-Mg alloy bulk in a crucible and induction heating to 700 ℃ to generate steam while melting, the generated Zn-Mg vapor is collected in the Vapor Box, the vapor is uniformly sprayed on the steel sheet through a nozzle Zn A Mg coating layer (2 μm) was formed.

The thickness of the oxide film was measured on the surface of the steel sheet thus obtained using a high resolution electron microscope. As shown in FIG. 5, a Zn-Mg coating layer 8 was formed on the surface of the steel sheet 3, and the interface 8 was formed. It was confirmed that no oxide film exists in the.

Reference Example 2

The oxide film was removed in the same manner as in Reference Example 1, and a Zn-Mg coating layer was deposited. However, the total power supplied was changed to 80 kW and the feed rate of the steel sheet was changed to 200 m / min.

The thickness of the oxide film was measured on the surface of the steel sheet thus obtained using a high resolution electron microscope. As shown in FIG. 5, a Zn-Mg coating layer 8 was formed on the surface of the steel sheet 3, and the interface 8 was formed. It was confirmed that the oxide film does not exist in).

It can be seen from the above Reference Examples 1 and 2 that the adhesion strength is remarkably improved as compared to Comparative Example 1 in which the oxide film 5 is present on the steel sheet surface.

Example 1

A cold rolled steel sheet with a natural oxide thickness of 10 nm was supplied at 200 m / min into a chamber equipped with a sputter having a maximum power of 5 kW per sputter module, and the etching power to the steel sheet and the adhesion when the Zn-Mg coating layer was deposited on the steel sheet were measured. Tested.

Etching was performed in the same manner as in Reference Example 1 to remove the oxide film on the surface of the steel sheet and to deposit a Zn-Mg coating layer. However, the number of chambers was changed to eight, and the total power supplied was changed to 40 kW.

A high-resolution electron micrograph was taken of the cross section of the steel sheet having the Zn-Mg coating layer thus obtained. It was confirmed that an oxide film existed between the steel sheet and the Zn-Mg coating layer, and the thickness of the oxide film was approximately 5 nm. This is shown in FIG. 6.

When the adhesion of the Zn-Mg coating layer to the obtained steel sheet was compared with the adhesion of the coating layer of the steel sheets obtained in Reference Examples 1 and 2, it could be confirmed that they had an equivalent level of adhesion.

The adhesion between the steel sheets obtained in Reference Examples 1 and 2 and that of the steel sheets obtained in Example 1 were compared. In the case of Example 1, although the oxide film 5 of about 5 nm was present, the oxide film It was confirmed that it had an adhesive force equivalent to the case of the reference examples 1 and 2 removed completely.

As can be seen from these results, even if 100% etching is not performed as in Example 1, the same adhesion as in Reference Examples 1 and 2 can be obtained, which is significantly less than power and equipment for 100% etching. Since power and equipment can be used, the oxide film can be etched economically to obtain the same adhesion.

Example 2

Etching force for the steel sheet when a cold rolled steel sheet having a natural oxide thickness of 10 nm is supplied at 200 m / min into a chamber having a sputter having a maximum power of 5 kW per sputter module, and a Zn-Mg coating layer is deposited on the steel sheet. Adhesion was tested.

The oxide film was removed in the same manner as in Reference Example 1, and a Zn-Mg coating layer was deposited. However, the number of chambers was changed to four, and the total power supplied was changed to 20 kW.

The high resolution electron microscope of the cross section of the steel plate which has the Zn-Mg coating layer obtained by this confirmed that an oxide film exists between the steel plate and Zn-Mg coating layer, and the thickness of the oxide film was about 6-7 nm.

When the adhesion of the Zn-Mg coating layer to the obtained steel sheet was compared with the adhesion of the coating layer of the steel sheets obtained in Reference Examples 1 and 2, it could be confirmed that they had an equivalent level of adhesion.

As can be seen from these results, even if 100% etching is not performed as in Example 2, the same adhesion as that of Reference Examples 1 and 2 can be obtained, which is significantly less than power and equipment for 100% etching. Power and equipment can be used, so that the oxide film can be etched economically to achieve the same adhesion.

1: anode box 2: plasma 3: steel plate 4: magnet
5: oxide film 6: Cu deposited layer 7: Zn-Mg
8: Interface between steel plate and Zn-Mg coating layer

Claims (8)

One or two chambers and a plasma generating device installed inside the chamber;
By measuring the thickness of the natural oxide film present on the surface of the steel sheet, by supplying power to generate a plasma to etch the natural oxide film formed on the surface of the steel sheet passing through the chamber, the natural oxide film remaining on the surface of the steel sheet after the etching is the natural Etching the natural oxide film on the surface of the steel sheet to be etched to remain at a thickness of 70% or less (except 0) based on the oxide film thickness; And
Forming a dry coating layer on the surface of the steel sheet subjected to the natural oxide film etching by plasma, electron beam or heat. The method of claim 1, wherein the natural oxide film remaining on the surface of the steel sheet after etching has a thickness of 7 nm or less (excluding 0). The method of claim 1, wherein the chamber includes a magnet on the top of the chamber that focuses the generated plasma to increase the density of the plasma. The method of claim 1, wherein the thickness of the natural oxide film is measured by using a high resolution electron microscope and an EDS. delete A dry coating layer formed on the surface of the steel sheet by plasma, electron beam, or heat, wherein an oxide film having a thickness of 70% or less (excluding 0) is present between the steel sheet and the coating layer, except for 0. Steel sheet with good adhesion. The steel sheet having excellent adhesion to the coating layer according to claim 6, wherein a natural oxide film having a thickness of 7 nm or less (excluding 0) exists between the steel sheet and the coating layer. delete

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