KR101177605B1 - Oxide coating on magnesium alloy with anti-corrosion and anti-microbial properties and Manufacturing method thereof - Google Patents

Abstract

In the oxidation coating layer of the magnesium alloy having corrosion resistance and antibacterial properties according to the present invention, in the oxide coating layer formed on the surface of the magnesium alloy, the oxide coating layer is composed of a porous layer on the surface and a dense layer therein, the porous layer Alternatively, the dense layer may contain 0.1 to 2.0 atomic% of silver (Ag). In addition, the method for producing an oxide coating layer of magnesium alloy excellent in corrosion resistance and antibacterial according to the present invention, (a) selected from sodium silicate (Na2SiO3) or sodium aluminate (sodium aluminate, NaAlO2), and fluorinated Preparing an electrolyte solution comprising one of potassium (KF), potassium hydroxide (KOH) or sodium hydroxide (NaOH) and silver nitrate (AgNO 3), and (b) immersing the magnesium alloy in the electrolyte solution. And forming a magnesium oxide coating layer by micro arc oxidation (MAO).

Magnesium Alloy, Micro Arc Oxidation (MAO), Silver Nitrate, Silver, Corrosion Resistance, Antibacterial

Description

Oxide coating on magnesium alloy with anti-corrosion and anti-microbial properties and Manufacturing method

The present invention relates to an oxide coating layer of a magnesium alloy and a method for manufacturing the same, and more particularly, to an oxide coating layer of a magnesium alloy excellent in corrosion resistance and antibacterial property by a micro-arc oxide (MAO) treatment and a method of manufacturing the same. It is about.

Magnesium and its alloys have excellent physical and mechanical properties, such as low density, good specific strength, specific stiffness, castability, machinability, vibration and shock absorption, and fatigue properties, and because of their easy recyclability, It is widely used in computers, electronic and communication components, industrial equipment and leisure-sports goods. However, magnesium is the most chemically active metal among commercial metals, and its standard electrode potential is -1.55V, which corrodes very quickly in air or in solution. In particular, it shows very poor corrosion characteristics in the environment containing Cl ⁻ ions. Therefore, in order to commercialize magnesium products, a surface treatment method for enhancing corrosion resistance by chemically, electrochemically or physically treating the surface of the product is required. Representative surface treatment methods for magnesium and its alloys include anodization, chemical coating, electrochemical plating, PVD coating and organic coating, among them micro-arc oxidation based on traditional anodization (MAO: Micro-arc). Oxidation) can form a thick, hard and highly adhesive oxide oxide coating on the surface of magnesium, thereby significantly increasing the corrosion and wear resistance of the magnesium material. Although the characteristics and microstructure of the microarc oxide coating layer are varied by various process variables, the chemical composition of the electrolytic solution is known to play an important role in determining the characteristics of the oxide coating layer.

Therefore, in order to further improve the corrosion resistance characteristics of the oxidized oxide coating layer of magnesium alloy, various studies on the composition of the electrolyte solution and the processing conditions (potential, application time, pH, ionic conductivity, etc.) in the micro arc oxidation are actively conducted. In the process. On the other hand, when the magnesium alloy is used for direct contact with the human body, for example, when the magnesium alloy is applied to computers, electronic and communication components, leisure-sports goods, etc. Although the surface of the product may be contaminated by the equality of bacteria and may have a harmful effect on the human body, no studies on the antimicrobial resistance of magnesium products have been published.

The present invention has been made in view of the above, an object of the present invention to provide an oxide coating layer of magnesium alloy excellent in corrosion resistance and antibacterial using a micro arc oxidation process.

Still another object of the present invention is to provide a method for producing an oxide coating layer of magnesium alloy having excellent corrosion resistance and antibacterial property.

Oxide coating layer of magnesium alloy excellent in corrosion resistance and antibacterial property according to the present invention for achieving the above object, in the oxide coating layer formed on the surface of the magnesium alloy, the oxide coating layer is composed of a porous layer of the surface and the dense layer inside In the porous layer or the dense layer, silver (Ag) is characterized in that it comprises 0.1 to 2.0 atomic%.

The oxide coating layer preferably has a thickness of 10 ~ 20㎛.

Method for producing an oxide coating layer of magnesium alloy excellent in corrosion resistance and antimicrobial to achieve the above another object, (a) selected from sodium silicate (Na ₂ SiO ₃ ) or sodium aluminate (NaAlO ₂ ) Preparing an electrolyte solution comprising one, one selected from potassium fluoride (KF), potassium hydroxide (KOH) or sodium hydroxide (NaOH), and silver nitrate (AgNO ₃ ); And (b) immersing the magnesium alloy in the electrolyte solution and forming an oxide coating layer by micro arc oxidation (MAO).

In the step (a), the sodium silicate or sodium aluminate is 10g based on 1L of the electrolyte solution, the potassium fluoride or potassium hydroxide or sodium hydroxide 3g ~ 9g, and the silver nitrate 0.167g ~ 1.018g desirable.

In the step (b), the applied voltage is preferably 350V ~ 500V, the application time of the voltage is preferably 10min ~ 30min.

In the step (b), the applied current is preferably 2.7A / dm ² (0.027A / cm ² ) ~ 7.4A / dm ² (0.074A / cm ² ), the application time of the current is 5min ~ 10min It is preferable.

According to the oxide coating layer of the magnesium alloy and the method for producing the same according to the present invention, not only the corrosion resistance is further improved, but also excellent effect of providing excellent antibacterial property on the surface of the oxide coating layer compared to the existing magnesium alloy. Therefore, the application of magnesium material can be further expanded because it is possible to prevent infection from bacteria by improving the function of the product due to the excellent corrosion resistance in the industrial field where magnesium alloy is applied and giving antimicrobial property to the surface of the product.

The above objects, features and other advantages of the present invention will become more apparent by describing the preferred embodiments of the present invention in detail with reference to the accompanying drawings. Hereinafter, a method of preparing an oxide coating layer of magnesium alloy having excellent corrosion resistance and antibacterial properties and an oxide coating layer of magnesium alloy according to an embodiment of the present invention will be described in detail.

1 is a view showing an experiment for micro arc oxidation (MAO) according to an embodiment of the present invention. Referring to FIG. 1, the positive electrode material 130 connected to the positive electrode and the negative electrode material 120 connected to the negative electrode are immersed in the electrolyte solution 110 inside the reservoir 100. When power is supplied from the power supply device 140 in the constant voltage mode and the constant current mode, anodization reaction proceeds and an oxide coating layer (oxidation coating layer) is formed on the surface of the cathode material. As the cathode material, magnesium alloys such as AZ31 and AD91D, which form an oxide coating layer, are applied, and the anode material may be made of stainless steel or the like.

The power supply 140 may operate in a constant current mode as well as a constant voltage mode.

The electrolyte solution 110 is selected from sodium silicate (Na ₂ SiO ₃ ) or sodium aluminate (NaAlO ₂ ), potassium fluoride (KF), potassium hydroxide (KOH) or sodium hydroxide (NaOH). ), And silver nitrate (AgNO ₃ ).

The basic electrolyte component sodium silicate or sodium aluminate is preferably 10 g based on 1 L of the electrolyte solution.

In addition, potassium fluoride, potassium hydroxide or sodium hydroxide, which are electrolyte additives, is preferably 3 g to 9 g based on 1 L of the electrolyte solution.

In addition, 0.167 g-1.018 g (0.001 mol-0.006 mol) are preferable based on 1 L of silver electrolyte solutions.

The concentration of silver nitrate is 0.001mol to 0.006mol in consideration of the amount of silver (Ag) in the oxide coating layer, the characteristics of the oxidation oxidation coating layer and excellent corrosion resistance and antibacterial properties. If the concentration is lower than this, the content of Ag in the oxide coating layer is decreased. If the concentration is higher than this, defects are generated on the surface and the inside of the oxide coating layer, and the optimum value is 0.003 mol (0.509 g).

The reason why the concentration of the additive, potassium fluoride, potassium hydroxide or sodium hydroxide was determined to be 3g to 9g was determined in consideration of the uniformity of the porous material, smoothness and cleanliness of the surface, and corrosion characteristics. Appeared. On the other hand, all of the oxide coating layer formed from the electrolyte solution to which the additives are applied can obtain satisfactory corrosion resistance and antimicrobial properties, of which the oxide coating layer when potassium fluoride is used has the most satisfactory corrosion resistance.

In addition, when the concentration of the additive is increased or the concentration of the silver nitrate is increased, the phenomenon is difficult to dissolve in the solution, it is not preferable because a uniform oxide coating layer is not formed in other concentration conditions than the above concentration conditions.

Hereinafter, a method of manufacturing an oxide coating layer of magnesium alloy according to the present invention will be described.

Method for producing an oxide coating layer of magnesium alloy according to the present invention is largely, (a) sodium silicate (sodium silicate, Na ₂ SiO ₃ ) or sodium aluminate (sodium aluminate, NaAlO ₂ ) and potassium fluoride (KF 1) preparing an electrolyte solution comprising one selected from potassium hydroxide (KOH) or sodium hydroxide (NaOH), and silver nitrate (AgNO ₃ ), and (b) immersing the magnesium alloy in the electrolyte solution. Forming an oxide coating layer by micro arc oxidation (MAO).

Meanwhile, a preliminary step of step (a) may be performed to prepare a magnesium alloy specimen and wash to remove impurities on the contaminated surface. The cleaning process generally involves cleaning the surface with a cleaning agent.

Step (a) is to prepare an electrolyte solution, to prepare the electrolyte solution in a reservoir as shown in FIG. Since the details of the electrolyte solution have been described above, the detailed description thereof will be omitted.

Meanwhile, according to the present invention, the pH of the electrolyte solution is preferably 11.5 to 13.0, and the ion conductivity is preferably 10.0 to 16.OmS.

The ionic conductivity and pH of the electrolyte solution vary depending on the components in the electrolyte solution, which greatly affects the anodic oxidation reaction (surface flame reaction-breakdown voltage, initial ignition time) during the MAO treatment. As a result, the properties (thickness, surface shape, corrosion characteristics, etc.) of the surface oxide coating layer are changed. As the concentration of the solute in the electrolyte solution increases, the ionic conductivity increases, and when the ionic conductivity is high, the amount of charge that causes the electrode reaction increases, which leads to an active anodic oxidation reaction. However, high ionic conductivity does not result in an ideal anodic oxidation reaction, and it is confirmed that the most effective oxide coating layer is obtained at the kind of electrolyte solution and the specific pH and ionic conductivity accordingly, and the range is as described above.

Next, the step (b) of immersing the magnesium alloy in the electrolyte solution and performing a micro arc oxidation process to form an oxide layer on the surface thereof.

As the cathode material, magnesium alloy is connected to the anode, and stainless steel is used as the cathode material.

In the MAO condition, the applied voltage is preferably 350 to 500 V, and the application time is preferably 10 to 30 min. The most optimal condition is measured at an applied voltage of 450 V and an application time of 30 min.

In the case of voltage, the higher the applied voltage and the longer the applied time, the greater the amount of surface flame reaction, and thus the higher the probability that Ag dissolved in the solution penetrates into the oxide coating layer. The amount of Ag in the oxide coating layer affects the antimicrobial and corrosion resistance properties of the sample. In addition, the amount of F dissolved in the solution increased in addition to Ag in the oxide coating layer formed from the electrolytic solution to which potassium fluoride was added, and a larger amount was detected than when Ag was not added. The presence of F in the oxide coating layer has been reported to increase the corrosion properties. However, if it is more than 500V, the flame reaction on the surface is so violent that it is difficult to keep the time long, so that the effect is not sufficiently seen.

On the other hand, in the MAO condition, the applied current is preferably 2.7 A / dm ² (0.027 A / cm ² ) to 7.4 A / dm ² (0.074 A / cm ² ), and the application time is 5 min to 10 min. Too much if the applied current exceeds 7.4A / dm ² Due to the high current density, more intense surface flame reactions occur than under constant voltage conditions, and the surface also becomes unsmooth. If the applied current is less than 2.7 A / dm ² , an oxide film is formed, but Ag may not enter the surface sufficiently. There is a problem. When the additive is potassium fluoride (KF), the applied current is most preferably 7.4 A / dm ² , and when the additive is potassium hydroxide (KOH) or sodium hydroxide (NaOH), the applied current is 2.7 A / dm ² . desirable.

For reference, when sufficient anodic oxidation occurs during the MAO process, the yellow electrolytic solution turns black before the reaction, and yellow and reddish brown oxide coating layers are obtained on the surface.

On the other hand, the oxidation coating layer of the magnesium alloy excellent in corrosion resistance and antibacterial according to the present invention prepared by the manufacturing method will be described.

Referring to FIG. 2, an oxide coating layer (oxide film) is formed on the surface of a magnesium alloy, and is composed of an inner dense layer ③ having a boundary between the porous layer ① and the interface layer ② of the surface. The porous layer or the dense layer contains 0.1 to 2.0 atomic% of silver (Ag).

Composition ratio (atomic%) of the magnesium alloy oxide coating layer according to the present invention O Mg Si F Ag ① 43.2 34.8 17.5 - 1.8 ② 11.0 74.8 12.5 - - ③ 4.7 87.7 2.3 5.2 -

Referring to Table 1 and FIGS. 2 and 3, Ag is mainly present in the porous layer ① among the oxide coating layers, and F is mainly present in the dense layer ③.

On the other hand, referring to Figures 2 and 3, it can be seen that the thickness of the oxide coating layer is about 15㎛. The boundary between the oxide coating layer and the magnesium alloy, that is, the boundary between the dense layer ③ and the magnesium alloy, is not clear as shown.

Hereinafter, the embodiment according to the present invention will be described in detail. However, the following examples are merely described for the purpose of more clearly expressing the present invention and do not limit or limit the present invention.

Example 1

AZ31 magnesium alloy was used as the MAO substrate, and the chemical composition is shown in Table 2 below.

Chemical Composition of AZ31 Magnesium Alloy Al Zn Mn Si Cu Ca Ni Fe Impurity Mg 2.5 to 3.5 0.6 to 1.4 0.2-1.0  <0.1 <0.05 <0.04 <0.005 <0.005 0.3 Remains

After the specimen of AZ31 magnesium alloy (24 mm x 49 mm x 2.5 mm) was prepared and the surface was polished with # 400 to # 2000 sandpaper, the surface was washed with acetone, ethanol and distilled water. Next, an electrolyte solution containing 10 g of sodium silicate (Na ₂ SiO ₃ ), ₃ g of potassium fluoride (KF), and 0.509 g of silver nitrate (AgNO ₃ ) in the reservoir (the concentration is based on 1 L of the electrolyte solution). ) (Ie, the electrolyte solution is Na ₂ SiO ₃ + KF + AgNo ₃ ). Next, the AZ31 magnesium alloy specimen was immersed in the electrolyte solution as the cathode material, and a stainless steel plate (50 mm × 100 mm × 1 mm) was immersed in the electrolyte solution as the anode material. On the other hand, the pH of the electrolyte solution is 11.65, the ionic conductivity is 10.70mS. Thereafter, a voltage of 450 V was applied for 30 min using a DC pulse power supply as a MAO condition. After MAO, the specimen of AZ31 magnesium alloy was washed with ethanol and dried.

Example 2

Except that 10 g of sodium aluminate (NaAlO ₂ ) was used instead of sodium silicate (Na ₂ SiO ₃ ) in the electrolyte solution (ie, the electrolyte solution was NaAlO ₂ + KF + AgNO ₃ ). , MAO treatment was performed in the same manner as in Example 1.

Example 3

Instead of applying voltage as the MAO condition, a current of 7.4 A / dm ² A MAO treatment was performed in the same manner as in Example 1, except that 5 min was applied.

Example 4

Instead of applying voltage as the MAO condition, a current of 7.4 A / dm ² A MAO treatment was performed in the same manner as in Example 2, except that 5 min was applied.

Example 5

A MAO treatment was performed in the same manner as in Example 1, except that AZ91D magnesium alloy was used instead of AZ31 as the MAO substrate. The chemical composition of AZ91D is shown in Table 3 below.

Chemical Composition of AZ91D Magnesium Alloy Al Zn Mn Si Fe Cu Ni Impurity Mg 8.5-9.5 0.45-0.9 0.17-0.4  <0.05 <0.004 <0.025 <0.001 0.3 Remains

Comparative Example 1

After the specimen of AZ31 magnesium alloy (24 mm x 49 mm x 2.5 mm) was prepared and the surface was polished with # 2000 sandpaper, the surface was washed with acetone, ethanol and distilled water. Next, an electrolyte solution containing 10 g of sodium silicate (Na ₂ SiO ₃ ) and ₃ g of potassium fluoride (KF) (the concentration is based on 1 L of the electrolyte solution) was injected into the reservoir (ie, the electrolyte solution was Na _2). SiO ₃ + KF). Next, the AZ31 magnesium alloy specimen was immersed in the electrolyte solution as the cathode material, and a stainless steel plate (50 mm × 100 mm × 1 mm) was immersed in the electrolyte solution as the anode material. On the other hand, the pH of the electrolyte solution is 11.86, the ionic conductivity is 10.74mS. After that, a voltage of 450 V was applied for 30 min using a DC pulse power supply as a MAO condition. After MAO, the specimen of AZ31 magnesium alloy was washed with ethanol and dried.

Comparative Example 2

Except for using 10 g of sodium aluminate (NaAlO ₂ ) instead of sodium silicate (Na ₂ SiO ₃ ) as the basic electrolyte component in the electrolyte solution (ie, the electrolyte solution is NaAlO ₂ + KF), Comparative Example Performed in the same manner as 1 to coat the magnesium alloy.

Comparative Example 3

Instead of applying voltage as the MAO condition, a current of 7.4 A / dm ² Except that applied for 5 minutes, it carried out in the same manner as in Comparative Example 1 to coat the magnesium alloy.

Comparative Example 4

Instead of applying voltage as the MAO condition, a current of 7.4 A / dm ² Except that applied for 5 minutes, it was carried out in the same manner as Comparative Example 2 to coat the magnesium alloy.

Test Example 1

Morphological Microstructure Measurement of Surface of Oxide Coating Layer

The morphological microstructure of the surface of the oxide coating layer of the magnesium alloy according to the embodiment of the present invention was observed with a scanning electron microscope (Scanning Electron Microscopy, SEM) and the results are shown in FIGS. 4 to 9.

4 is a scanning microscope picture of the surface of the oxide coating layer according to Example 1, Figure 5 is a scanning microscope picture of the surface of the oxide coating layer according to Example 2, Figure 6 is a scanning microscope picture of the surface of the oxide coating layer according to Example 3, Figure 7 Is a scanning microscope picture of the surface of the oxide coating layer according to Example 4, Figure 8 is a scanning microscope picture of the surface of the oxide coating layer according to Example 5. On the other hand, Figure 2 described above is to observe the cross section of the magnesium alloy oxide coating layer according to Example 1 by scanning micrograph.

9 and 10 are scanning electron micrographs of the surface of the oxide coating layer according to Comparative Example 1 and Comparative Example 2.

2 and 4, the oxide coating layer has a porous shape having pores of several micrometers, and as described above, the oxide coating layer is composed of a porous layer and a dense layer inside. Ag-containing oxide coatings impart antimicrobial properties to magnesium alloys, and in particular, the dense layer inside is a key functional layer that provides excellent corrosion resistance as well as antibacterial properties. Although experimental confirmation is required additionally, antimicrobial properties are predominantly influenced by Ag, and corrosion properties are thought to be related to Ag and dense layers at the same time.

Meanwhile, referring to FIG. 9, the oxide coating layer formed from the electrolyte solution containing no silver nitrate (AgNO ₃ ) shows a porous surface phenomenon similar to that of the oxide coating layer formed from the electrolyte solution containing silver nitrate (see FIG. 4).

Referring to FIG. 5, the surface of the oxide coating layer formed from an electrolyte solution containing sodium aluminate (NaAlO ₂ ) as the main electrolyte component is an electrolyte solution containing sodium silicate (Na ₂ SiO ₃ ) as the main electrolyte component. Compared to the surface of the oxide coating layer formed in FIG. 4, the pore size and low porosity are shown. In addition, referring to FIG. 10, an oxide coating layer formed of an electrolyte solution containing sodium aluminate (NaAlO ₂ ) as a main electrolyte component and containing no silver nitrate (AgNO ₃ ) may also be oxidized from an electrolyte solution containing silver nitrate. It shows a porous surface shape similar to the coating layer (see FIG. 4), whereby it can be seen that the inclusion of Ag does not significantly affect the surface shape. However, the inclusion of a certain amount of Ag in the oxide coating layer has a large effect on the corrosion resistance and antibacterial properties, which will be described later in detail.

6 and 7, it can be seen that the oxide coating layer treated under the constant current condition in the MAO process has lower porosity than the constant voltage condition. On the other hand, although not shown, according to experiments, the oxide coating layer treated in the electrolyte solution containing no silver nitrate (AgNO 3) has almost no pores and shows a dense surface shape.

Test Example 2

Determination of Ag Content by Chemical Composition of Oxide Coating Layer and Magnesium Alloy Type

Figure 11 shows the results of the energy dispersive component analyzer (SEM-EDS) analysis of the oxide coating layer prepared by Example 1 and Example 2, Comparative Example 1 and Comparative Example 2.

As shown, in the oxide coating layer of the magnesium alloy prepared by Example 1 (the electrolyte solution is Na ₂ SiO ₃ + KF + AgNo ₃ ) Ag and F other than Mg, Si, O was detected, but in Comparative Example 1 Only Mg, Si, and O were detected in the oxide coating layer of the magnesium alloy manufactured by the present invention. In addition, in the oxide coating layer of the magnesium alloy prepared by Example 2 (the electrolyte solution is NaAlO ₂ + KF + AgNo ₃ ), Ag and F were detected in addition to Mg, Al, and O, but the magnesium alloy prepared by Comparative Example 2 Only Mg, Al, and O were detected in the oxide coating layer of.

On the other hand, Figure 12 shows the component analysis (SEM-EDS) results of the oxide coating layer prepared in Example 1 and Example 5. Referring to the drawings, the oxide coating layer formed on the AZ91D magnesium alloy of Example 5 showed a relatively higher content of Ag than the oxide coating layer formed on the AZ31 magnesium alloy of Example 1, but the oxide coating layer obtained by Example 5 Compared with the oxide coating layer formed on AZ31, the surface of the oxide coating layer was not uniform, and there were many defects in the oxide coating layer. It is thought that this affects the corrosion characteristics of the sample, and the corrosion evaluation results show that the oxidation coating layer coated on the AZ91D magnesium alloy is not better than the oxidation coating layer coated on the AZ31 magnesium alloy.

Test Example 3

Corrosion Resistance Evaluation

13 to 15 show the results of corrosion resistance by potentiodynamic test.

Figure 13 shows the corrosion resistance of the oxide coating layer of the magnesium alloy prepared by Example 1 and Comparative Example 1, and the pure magnesium alloy untreated. In the case of the oxide coating layer obtained from the electrolyte solution containing silver nitrate as in Example 1, it shows a higher corrosion potential and a lower current density than the oxide coating layer obtained from the electrolyte solution containing no silver nitrate as in Comparative Example 1. This means that in the case of the oxide coating layer according to Example 1, the potential of corrosion is higher and the progression speed is very slow after the corrosion occurs, which means higher corrosion resistance than Comparative Example 1. On the other hand, the oxidation coating layer according to Example 1 and Comparative Example 1 can be seen that the corrosion rate is very low compared to the uncoated AZ31 magnesium alloy, which means that the coated magnesium alloy has a high corrosion resistance.

Figure 14 shows the corrosion resistance of the magnesium alloy prepared by Example 2 and Comparative Example 2, and the uncoated pure magnesium alloy, respectively. Also in this case, it can be seen that the oxide coating layer obtained from the electrolyte solution containing silver nitrate of Example 2 has higher corrosion resistance than the oxide coating layer obtained from the electrolyte solution containing no silver nitrate as in Comparative Example 2. On the other hand, in the case of the oxidation coating layer according to Example 2, the anodic oxidation behavior after corrosion shows a passivation behavior, similar behavior in the oxide coating layer according to Comparative Example 2. This is a big difference compared with the fact that the behavior in Example 1 and Comparative Example 1 in which the main main electrolyte component was treated in another electrolyte solution was not clearly observed.

Figure 15 shows the corrosion resistance of the magnesium alloy oxide coating layer prepared in Example 1 and Example 3 and the uncoated pure magnesium alloy, respectively. As shown, in the case of magnesium alloy treated in the same electrolyte solution, it can be seen that the difference according to the applied potential (constant voltage or constant current) is not large, both have excellent corrosion resistance compared to pure magnesium alloy.

16 is a table showing the results of the anticorrosion test of Examples 1 to 5, Comparative Example 1 and Comparative Example 2, uncoated magnesium alloy. As a result of the coincidence test, the oxide coating layer containing Ag has a corrosion resistance of several tens of times to one hundred times that of the oxide coating layer containing no Ag. In particular, in the case of Example 1, it can be confirmed that the polarization resistance (R _p ) is very large 10㏁ ㎠. On the other hand, the uncoated AZ31 and AX91D magnesium alloys have a low polarization resistance of 10 m 2 or less, and the oxidation coating layer without Ag exhibits a polarization resistance of 120 m 2 or less. This means that the oxide coating layer containing Ag according to the present invention has high corrosion resistance.

Test Example 4

Antimicrobial Evaluation

FIG. 17 is a blank to which no sample is added, and a sample of Staphylococcus aureus ATCC 6583 and Escherichia coli (Escherichia coli ATCC 8739) to each medium to which a magnesium alloy sample (MAO-sample) according to Example 1 is added. The results of the antimicrobial test for the table is shown, Figure 18 shows the surface photos for each after 24 hours in the conditions of Figure 17.

As shown in FIGS. 17 and 18, after 24 hours, the bacteria increased in the case of Blank, but in the case of the sample according to Example 1, the germs were almost eliminated. In Fig. 17, it means that the population of bacteria is less than 10. If the value of anti-microbial activity is less than 5 for Staphylococcus aureus, all bacteria are eliminated if less than 7 for Escherichia coli. As Staphylococcus aureus is 4.6 and Escherichia coli shows 6.4, it can be seen that it has very excellent antibacterial activity.

Although a preferred embodiment of the present invention has been described above, those skilled in the art will understand that many modifications and changes can be made without departing from the spirit of the present invention as set forth in the claims below. Such parts may also be considered to be within the scope of the present invention.

1 is a diagram showing an experiment for micro arc oxidation (MAO) according to a preferred embodiment of the present invention,

Figure 2 is a scanning micrograph of the vertical cross section of the magnesium alloy coated with an oxide coating layer excellent in corrosion resistance and antibacterial according to the present invention,

3 is a view measuring the thickness of the oxide coating layer according to the present invention through the EDS line analysis;

4 is a scanning micrograph of the surface of the oxide coating layer according to Example 1 of the present invention,

5 is a scanning micrograph of the surface of the oxide coating layer according to Example 2 of the present invention,

6 is a scanning micrograph of the surface of the oxide coating layer according to Example 3 of the present invention,

7 is a scanning micrograph of the surface of the oxide coating layer according to Example 4 of the present invention,

8 is a scanning micrograph of the surface of the oxide coating layer according to Example 5 of the present invention,

9 and 10 are scanning micrographs of the surface of the oxide coating layer according to Comparative Examples 1 and 2,

11 is a graph showing the results of energy dispersive component analyzer (SEM-EDS) analysis showing the composition of the magnesium alloy surface according to Examples 1 and 2, Comparative Examples 1 and 2,

12 is a graph showing an energy dispersive component analyzer (SEM-EDS) analysis result showing the composition of magnesium alloy surfaces according to Examples 1 and 9;

13 is a graph showing the results of corrosion resistance by the coincidence test of the magnesium alloy oxidized coated and uncoated pure magnesium alloy according to Example 1, Comparative Example 1,

14 is a graph showing the results of corrosion resistance by the coincidence test of the magnesium alloy oxide-coated and uncoated pure magnesium alloy according to Example 2, Comparative Example 2,

15 is a graph showing the results of corrosion resistance by the coincidence test of the magnesium alloy oxide coated and uncoated pure magnesium alloy by Examples 1 and 3,

16 is a coin point corrosion test result table,

17 is an antimicrobial test result table of an oxide-coated magnesium alloy sample according to Example 1,

FIG. 18 is a surface photograph thereof after 24 hours under the condition of FIG. 17.

Claims (11)

delete delete delete (a) selected from sodium silicate (Na ₂ SiO ₃ ) or sodium aluminate (NaAlO ₂ ), and selected from potassium fluoride (KF), potassium hydroxide (KOH) or sodium hydroxide (NaOH) One, and preparing an electrolyte solution containing silver nitrate (AgNO ₃ ); And, (b) immersing the magnesium alloy in the electrolyte solution and forming an oxide coating layer by micro arc oxidation (MAO). The method of claim 4, wherein In the step (a), based on 1L of the electrolyte solution, the sodium silicate or sodium aluminate contains 10g, the potassium fluoride or potassium hydroxide or sodium hydroxide 3g ~ 9g, silver nitrate 0.167g ~ 1.018g Method for producing an oxide coating layer of magnesium alloy having corrosion resistance and antibacterial properties. The method of claim 4, wherein In the step (b), the applied voltage is 350V ~ 500V characterized in that the corrosion-resistant and antimicrobial magnesium oxide alloy coating layer manufacturing method having an antimicrobial. The method of claim 6, The application time of the voltage is 10min ~ 30min characterized in that the corrosion-resistant and antimicrobial magnesium oxide alloy coating layer manufacturing method having an antimicrobial. The method of claim 4, wherein In the step (b), the applied current is 2.7A / dm ² (0.027A / cm ² ) ~ 7.4A / dm ² (0.074A / cm ² ) characterized in that the oxidation of the magnesium alloy having corrosion resistance and antimicrobial Coating layer manufacturing method. 9. The method of claim 8, The application time of the current is 5min ~ 10min characterized in that the corrosion-resistant and antimicrobial oxidation coating layer manufacturing method of magnesium alloy. The method of claim 4, wherein The magnesium alloy is AZ31 or AZ91D, characterized in that the corrosion-resistant and antimicrobial magnesium oxide alloy coating layer manufacturing method characterized in that. An oxide coating layer of magnesium alloy having corrosion resistance and antibacterial produced by the method of any one of claims 4 to 10.

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