KR20110073100A - Manufacturing method of the nano-structure on galvanized steel surface - Google Patents

Abstract

PURPOSE: A method for manufacturing a hot-dipped steel sheet with a surface nanostructure is provided to improve the adhesive force and coatability of a steel sheet by forming a nanostructure within seconds. CONSTITUTION: A method for manufacturing a hot-dipped steel sheet with a surface nanostructure is comprises a hot dipping process and a low-pressure plasma processing process. A steel sheet is hot-dipped in the hot dipping process. The low-pressure plasma processing process is performed in the steel sheet in 10-2~20 torr pressure. A nanostructure is formed on the surface of the steel sheet using inert gas and surface reforming agent.

Description

Manufacturing Method of the Nano-Structure on Galvanized Steel Surface

The present invention relates to a method for manufacturing a molten metal plated steel sheet comprising a hot dip plating step and a low pressure plasma treatment step, by combining the hot dip plating process and the low pressure plasma treatment process in combination, very dense and uniform to the surface of the hot dip plated steel sheet It is intended to provide a method of forming a nanostructure.

Recently, research on forming nano-structures on metal, semiconductor and non-conductor surfaces and applying them to next-generation surface treatment products has been actively conducted worldwide. Accordingly, efforts are being made in the steel industry to improve mechanical properties and surface modification using nanostructures.

The present invention is to provide a method of connecting the hot-dip galvanizing process and the plasma process complex, to form a very dense and uniform nanostructure on the surface of the hot-dip plated steel sheet.

Methods of forming nanostructures on a surface can be divided into two types. One of them is a bottom-up method, in which an image, vapor deposition, or polymer nanoparticles are distributed on a target surface, and a surface structure is formed using various self-assembly phenomena. In general, such nanostructures have a multi-layered structure due to deposition or coating of chemical components different from those on the target surface. The above method is not suitable for uniformly forming nanostructures on large areas in mass production, and because it is a multi-layered structure, additional material costs, other processes and equipment, and long manufacturing times are required, so the actual production process at high speed (about 100mpm) is required. It is difficult to apply to.

Another nanostructure manufacturing method is a Top-Down method. It is a method of artificially forming a desired nanostructure on a target surface by etching using an electron beam, a laser beam, high power X-rays, a focused ion beam, and the like. The above method is excellent in precision by manufacturing individual nanostructures sequentially using photo resistors, masks, etc., but there are also technical limitations in forming nanostructures on large surface areas.

As an alternative to this technique, it was proposed in 1999 by S. Facsko to form nanoscale quantum dots on a GaSb semiconductor surface very evenly using an ion beam plasma of an inert gas [S. Facsco et al . Science 285, 1551 (1999). The above method using ion beam has been very active on the surface of single crystal metal, and it is possible to form Nano Wire, Nano Dot, Nano Hole, etc. This is possible [G. Costantini et al, Phys. Rev. Lett. 86, 838 (2001), TC Kim et al. Phys. Rev. Lett 92, 246104 (2004). However, the above method requires an ion beam plasma in a high vacuum (10 ^-5 Torr or less) state, requires additional expensive equipment, is difficult to maintain, and is easy to form the nanostructure on the surface in a short time of several seconds. As a result, there are limitations in applying it to the actual industry.

The present invention is plasma-treated with an inert gas and surface modifiers such as oxygen, methane, silane gas, etc. on the surface of the hot-dip galvanized steel sheet, so that the nano-structure on the surface of the hot-dip galvanized steel sheet is very dense in a few seconds, the whiteness It is an object of the present invention to provide a method for producing a steel sheet having a high quality and at the same time modifying the surface into hydrophilic and hydrophobic. According to the present invention, it is possible to produce a multifunctional hot-dip galvanized steel sheet by evenly distributing very fine nanostructures in the sequined tissue without destroying the macroscopic dendritic sequined tissue on the surface of the hot-dip galvanized steel sheet.

Unlike the proposed techniques, the present invention does not require high vacuum in that it uses inert ion-low pressure plasma of several Torr, which is different from the existing technique and forms nanostructures within a few seconds. It is possible. The equilibrium between the etching of low-energy low-pressure plasma ions and the surface diffusion of atoms enables self-assembly to produce very dense and uniform nanostructures on the surface of the hot-dip galvanized steel sheet. Can improve. In addition, the ion beam irradiated surface exhibits a distinctive white color and the surface whiteness is superior to that of a conventional hot dip steel sheet.

Another feature of the present invention is that it is possible to modify the surface of the hot-dip steel sheet. When oxygen is added to the inert gas to generate a plasma, a surface having improved hydrophilicity can be prepared, and when a gas such as methane or silane is added, a surface having improved hydrophobicity can be provided.

The present invention differs from the prior art in that it is applied to a hot dip galvanized steel sheet rather than a single crystal semiconductor or metal. It is also different from the plasma technology (US 0190449) previously applied for degreasing or removing hot rolled scales of cold rolled steel sheets in terms of application and purpose.

Therefore, the present invention, which manufactures a nanostructure using low pressure plasma on a hot dip galvanized steel sheet, is unique in that it presents a new process that continuously links the hot dip plating process with the plasma process.

According to the present invention, the nanostructure is formed within a few seconds without requiring high vacuum, so that the nanostructure can be applied in a substantially continuous process, and the adhesion and coating property of the steel sheet can be improved, and excellent whiteness can be obtained. In addition, by connecting plasma processes such as low energy inert gas, oxygen, methane and silane gas to the end of the hot dip plating process, nanostructures of several hundred nanometers inside are evenly distributed without destroying structures of tens to hundreds of micrometers. There is an advantage that it is possible to manufacture a multi-functional hot-dip galvanized steel sheet that can form and control the surface modification.

The present invention is a hot-dip plating step; And it relates to a method of manufacturing a molten metal plated steel sheet comprising a low pressure plasma treatment step.

In the present invention, the low pressure plasma treatment step may be performed at 10 ⁻² to 20 torr, specifically 1 to 15 torr, and more specifically 5 to 10 torr.

In the low pressure plasma treatment step of the present invention, the ion energy of 0.1 to 10 keV can be given, and specifically, the ion energy of 0.5 to 5 keV can be given. In addition, a glow discharge method or an insulator discharge method may be used, but is not limited thereto.

In the low pressure plasma treatment step of the present invention, an inert gas and a surface modifier may be used to form nanostructures on the surface of the steel sheet. Nanostructures produced by the method of the present invention have a diameter of about 10 to 500 nm, more specifically 20 to 300 nm.

In this case, helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) or radon (Rn) may be used as the inert gas, but any inert gas may be used without limitation. have.

In addition, oxygen, methane, silane gas, etc. may be used as the surface modifier. For example, when a plasma is generated by adding a hydrophilic surface modifier such as oxygen to an inert gas, a surface having improved hydrophilicity may be prepared. When the plasma is generated by adding a hydrophobic surface modifier such as, it is possible to produce a surface with improved hydrophobicity.

The present invention includes a low pressure plasma treatment step to improve the whiteness of the plated steel sheet.

As the molten metal used in the molten metal plated steel sheet in the present invention, molten zinc, alloyed molten zinc, molten Zn-Al-Mg alloy, molten aluminum, molten Zn-Al alloy, molten Al-Si-Mg alloy However, it is not limited thereto.

In the present invention, a schematic diagram of a technique for manufacturing a hot-dip galvanized steel sheet having a nanostructure formed by linking the hot-dip and low-pressure plasma process is as shown in FIG.

In the present invention, the hot dip plating process follows the general process of annealing the cold rolled material. For example, the plating bath (1) temperature is 450 ~ 470 ℃, the plating bath composition can be made to contain 0.1 to 0.3% aluminum in zinc. The steel sheet passed through the plating bath can be subjected to cooling treatment (4) after adjusting the coating weight in the range of 80 to 600 g / m ² , for example, by a gas wiper (2) using air or nitrogen located at the top of the plating bath. It is also possible to undergo a process of advancing the solidification reaction prior to the cooling treatment to form a fine sequin, or to alloy (3) the base steel sheet and the plating layer, if necessary. In the alloying process of the hot-dip galvanized steel sheet, the temperature is, for example, about 500 ° C., and the plating layer is changed into an alloy layer containing zinc and about 10% of iron, and an alloyed steel sheet having excellent weldability and paintability can be manufactured. After cooling, skin pass treatment 5 and tension leveling 6 enable shape correction and the provision of macroscopic texture to the steel sheet.

The steel sheet is then subjected to a plasma treatment. Vacuum locks 7 and 9 are required before and after the plasma process, and the degree of vacuum is, for example, about 10 Torr. This low pressure plasma 8 is a Ne gas which is inert gas by high voltage (0.5 to 5 kV) induced at the electrodes configured at both sides. , Ar, Xe and the like may be formed while being ionized. The plasma apparatus may use a method such as glow discharge and dielectric barrier discharge. Such plasma may be provided continuously by controlling the flow of the vacuum pump apparatus and inert gas.

After the plasma process, nanostructures of several tens to hundreds of nanometers (nm) in size may be formed on the surface of the hot dip galvanized steel sheet in a very dense and dense manner. The plasma generating gas may be modified to be hydrophilic or hydrophobic by mixing a surface modifying agent such as oxygen or CH ₄ gas with an inert gas. Thereafter, if necessary, after treatment 10 such as chromic acid treatment, resin coating, or rust preventive oil treatment is performed, and the hot-dip steel sheet is wound in a coil form in the tension reel 11. Nanostructure forming method according to the present invention is hot dip galvanized, alloyed hot dip galvanized, hot dip Zn-Al-Mg-based alloy plating, hot dip aluminum plating, hot dip Zn-Al alloy plating, hot dip Al-Si-Mg alloy plating It can be used for continuous plating using molten metal.

Hereinafter, the present invention will be described in more detail through examples according to the present invention, but the scope of the present invention is not limited to the examples given below.

≪ Example 1 >

Carbon 0.04%, manganese 0.2%, low-carbon cold-rolled steel sheet containing silicon less than 0.01% (1.5mm X 1200mm) material for the plating bath 460 ^o and then a coating weight 120 g / m ² in C hot-dip galvanizing process, the high voltage charged phosphate The treatment gave an average sequin size of about 80 mm. Thereafter, glow discharge was performed for 1 second with Ar ion energy of 700 eV in Ar atmosphere and 9 Torr vacuum degree. Figure 2 shows the surface FE-SEM image of the embodiment, the nanostructures of about 100 ~ 200 nm size in the surface sequins are formed very evenly on the surface of the hot-dip galvanized steel sheet and excellent whiteness.

<Example 2>

Carbon 0.04%, manganese 0.2%, after the coating weight hot-dip galvanizing treatment to 90 g / m ² low-carbon cold-rolled steel sheet containing silicon less than 0.01% (0.7mm X 1000mm) material in a plating bath 460 ^o C, the roll roughness It was rolled with 1.0% elongation with a skin pass mill around 1.0 mm. Thereafter, glow discharge was performed for 1 second with Ne ion energy of 700 eV in Ar atmosphere and 9 Torr vacuum degree. Figure 3 shows the surface FE-SEM image of the example, in which the nanostructures of about 50 nm size were formed very evenly on the surface of the hot-dip galvanized steel sheet in the skin pass-treated macrostructure and had excellent whiteness.

1 is a schematic diagram of a continuous hot dip plating process and a low pressure plasma treatment process.

2 is a surface photograph of the FE-SEM (X 10000) for Example 1. FIG.

3 is a surface photograph of FE-SEM (X 10000) for Example 2. FIG.

Claims (8)

Hot-dip plating step; And Method of producing a molten metal plated steel sheet comprising a low pressure plasma treatment step. The method of claim 1 The low pressure plasma treatment step is a method of manufacturing a molten metal plated steel sheet, characterized in that carried out at 10 ^-2 to 20 torr. The method of claim 1 In the low pressure plasma treatment step, a method of manufacturing a molten metal plated steel sheet, characterized in that the ion energy of 0.1 to 10 keV, but using a glow discharge method or an insulator discharge method. The method of claim 1 In the low pressure plasma treatment step, Method for producing a molten metal plated steel sheet, characterized in that to form a nanostructure on the surface of the steel sheet using an inert gas and a surface modifier. The method according to any one of claims 1 to 4. The low pressure plasma treatment step of manufacturing a molten metal plated steel sheet, characterized in that for improving the whiteness of the steel sheet. The method of claim 4 Method for producing a molten metal plated steel sheet, characterized in that the inert gas is selected from the group consisting of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). . The method of claim 4 The surface modifier is selected from the group consisting of oxygen, methane and silane (Silane) method for producing a molten metal plated steel sheet. The method of claim 4 Method of producing a molten metal plated steel sheet, characterized in that the nanostructure has a diameter of 10 to 500nm.

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