KR101543924B1 - Color-treated magnesium and color-treatment method thereof - Google Patents

Abstract

The present invention relates to a magnesium color-treated and a magnesium color-development treatment method for the same, and a color-treated magnesium and a color-development treatment method thereof according to the present invention are characterized in that magnesium is immersed in a hydroxide solution to perform color development, And the color can be uniformly realized in a short time.

Description

COLOR-TREATED MAGNESIUM AND COLOR-TREATMENT METHOD THEREOF [0002]

The present invention relates to a color-treated magnesium and a magnesium color-treating treatment method therefor.

Magnesium is a metal belonging to an ultra-light metal among practical metals, has excellent abrasion resistance, is strong in sunlight and environmentally friendly, but has difficulty in realizing metal texture and various colors. In addition, since it is extremely active as an electrochemically lowest metal, if it is not color-treated, it is very quickly corroded in the air or in a solution, so that it is difficult to apply to industry.

In recent years, due to the trend toward lighter weight of the industry, the magnesium industry has been attracting attention, and research has been actively conducted to improve such problems of magnesium with the trend of metal casing materials in electric and electronic parts materials such as mobile phone case parts .

As a result, a PVD-sol-gel method in which a metal-containing material is dry-coated and then sol-gel coated to obtain a metal texture and corrosion resistance on a magnesium alloy surface; Anodic oxidation method for imparting gloss to the magnesium surface by chemical polishing and coloring the substrate surface by anodizing the magnesium base material with the basic electrolyte in which the pigment is dissolved has been developed (Patent Documents 1 and 2).

However, in the case of the PVD-sol-gel method, a metal texture is formed on the surface of the magnesium substrate, but it is not a metal texture inherent to magnesium, and it is difficult to realize various colors. In addition, when the surface of the magnesium substrate is color-treated by the anodic oxidation method, an opaque oxide film is formed on the surface of the substrate, and it is difficult to realize a metal texture unique to magnesium.

Therefore, in order to put magnesium into practical use, there is a desperate need for a technique for chemically, electrochemically, or physically treating the surface of a magnesium substrate to improve resistance to corrosion and to realize a desired color on the surface of magnesium.

Korean Patent Publication No. 2011-0016750; Korea Patent Publication No. 2011-0134769.

An object of the present invention is to provide a color-treated magnesium.

It is still another object of the present invention to provide a method for processing magnesium.

In order to achieve the above object,

In one embodiment, the present invention relates to a method of manufacturing a semiconductor device comprising: a magnesium matrix; And a hydroxide film formed on the surface of the magnesium matrix,

For a magnesium specimen of 1 cm in width and 1 cm in length,

The color coordinate deviations (DELTA L, DELTA a, DELTA b) for any three points present on the specimen provide the color-treated magnesium satisfying at least one of the following conditions: DELTA L < 0.6, DELTA a < 0.6 and DELTA b <

The present invention also provides, in another embodiment, a magnesium color development treatment method comprising the step of immersing magnesium in a hydroxide solution.

The color-treated magnesium according to the present invention and its color-development treatment method can improve the homogeneity and corrosion resistance of the magnesium metal surface by immersing the magnesium in the hydroxide solution and performing the color development treatment, and the color can be uniformly realized in a short time. Therefore, the color-treated magnesium can be usefully used in the fields of electric and electronic parts such as building exterior materials, automobile interior parts, and mobile phone case parts in which magnesium materials are used.

In Figure 1 is one embodiment, taking a surface of the color development processing magnesium image of the hydroxide solution the type: wherein, Ⅰ is the immersed specimen for 40 minutes in 100 ℃, 10% NaOH aqueous solution, Ⅱ is 100 ℃ , Specimens immersed in distilled water for 40 minutes, specimen III immersed in distilled water at 100 ° C for 1 hour; And IV are specimens immersed in distilled water at 100 DEG C for 2 hours;
FIG. 2 is an image of a surface of a magnesium-treated magnesium according to a kind of hydroxide solution in an embodiment using a scanning electron microscope: wherein I is a specimen immersed in a 10% NaOH aqueous solution at 100 ° C. for 40 minutes II is a specimen immersed in distilled water at 100 DEG C for 40 minutes, III is a specimen immersed in distilled water at 100 DEG C for 1 hour, And IV are specimens immersed in distilled water at 100 DEG C for 2 hours;
3 is a graph showing the CIE colorimeter;
7 is an image showing the thickness of the chromogenic film formed on the surface of magnesium and the shape of the surface according to the time during which the chromatic treatment is performed in one embodiment. In this case, A is an image obtained by measuring the thickness of a chromogenic film using a transmission electron microscope, and B is an image obtained by using a scanning electron microscope for the shape of a surface;
8 is an image showing the change in color of magnesium undergoing color development according to the immersion time of the magnesium hydroxide at 100 ° C and 10% concentration;
Fig. 9 shows the results of evaluating the surface corrosion resistance of magnesium according to whether or not color processing is performed in one embodiment. In this case, A is an image of the surface of the magnesium-untreated magnesium film, B is an image of the surface of the magnesium-colored magnesium;
10 is a graph showing a potentiodynamic polarization curve of magnesium according to whether or not a coloring treatment is performed and a treatment time in one embodiment;
FIG. 11 is an image of a result of performing a cross-cut tape test method of a color-treated magnesium including a clear layer in one embodiment. Here, A is an experimental result of a test piece including a matte clear coating layer And B is the experimental result for the specimen including the glossy / matt clear coating layer.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In the present invention, the term "comprises" or "having ", etc. is intended to specify that there is a feature, number, step, operation, element, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Hereinafter, the present invention will be described in detail with reference to the drawings, and the same or corresponding components are denoted by the same reference numerals regardless of the reference numerals, and a duplicate description thereof will be omitted.

In the present specification, "%" can be used as a concentration unit of a solution. Specifically, for example, a 10% NaOH solution means a solution in which 900 mL of water and 100 g of NaOH are mixed.

The present invention provides a color-treated magnesium and a magnesium color-treating treatment method therefor.

Conventionally, as a method of embodying a color in a magnesium material, a PVD-sol-gel method and an anodic oxidation method in which a magnesium-containing surface is coated with a metal-containing material or a pigment are known. However, these methods may not realize the metal texture inherent to magnesium, or the durability of magnesium may deteriorate. Further, it is difficult to realize a hue, and a coating layer to be coated easily peels off, failing to satisfy reliability.

In order to overcome these problems, the present invention proposes a magnesium coloring treatment method comprising a step of immersing magnesium in a hydroxide solution. The color-treated magnesium according to the present invention can uniformly realize hues within a short time by uniformly forming a hydroxide film on the surface of magnesium. At this time, since the magnesium is different in color to be implemented depending on the thickness of the hydroxide film formed on the surface, various colors can be realized. In addition, there is an advantage that the homogeneity and corrosion resistance of the magnesium metal surface can be improved.

Hereinafter, the present invention will be described more specifically.

The present invention relates to a magnesium matrix; And a hydroxide film formed on the surface of the magnesium matrix,

For a 1 cm X 1 cm magnesium specimen,

The color coordinate deviations (DELTA L, DELTA a, DELTA b) for any three points present on the specimen provide a chromogenic magnesium satisfying at least one of DELTA L &lE; 0.6, DELTA a < 0.6 and DELTA b < 0.5.

More specifically, the color-treated magnesium according to the present invention may satisfy at least two of the above conditions, and more specifically, satisfy all of the above conditions.

More specifically, in one embodiment, a magnesium specimen of 1 cm x 1 cm was immersed in a 10% NaOH aqueous solution at 100 DEG C for 40 minutes, and the color coordinates for any three points present on the specimen were measured. As a result, the color coordinate deviations satisfy all the above conditions with? L <0.06, 0.23?? A <0.31 and 0.01? B <0.21. Further, it was confirmed that ΔE derived from the above measured values was 0.237 ≦ ΔE <0.375, and the deviation of the color coordinates was remarkably small. This means that the color of the color-treated magnesium according to the present invention is uniform.

The magnesium coloring principle of the present invention utilizes the light scattering and refraction principle incident on the magnesium surface. That is, the color can be uniformly realized by forming a chromogenic film on the magnesium surface with a uniform thickness to scatter and refract light incident on the magnesium surface.

At this time, the thickness of the hydroxide film according to the present invention is not particularly limited, but may be 50 nm to 2 탆, more specifically, 100 nm to 1 탆.

Further, the color-developed magnesium according to the present invention can satisfy the following formula (1): &quot; (1) &quot;

[Equation 1]

Corrosion Rate (Corr. Rate) ≤ 0.01

Corrosion Rate (Corr. Rate) refers to the degree of corrosion of the color-treated magnesium at room temperature and 0.5% NaCl solution according to the electro-static polarization test, and the unit is mm / year. Here, the normal temperature may be 25 캜.

The color-treated magnesium according to the present invention may have an effect of improving the corrosion resistance by forming a hydroxide film on the surface of the magnesium matrix.

More specifically, in one embodiment, the corrosion resistance of magnesium was evaluated by performing a co-electrification test in 0.5% NaCl solution at room temperature for chromogenic and non-chromogenic magnesium according to the present invention. As a result, the corrosion rate (Corr. Rate) of the color-treated magnesium was 0.0004 to 0.0013 mm / year, while that of the colorless untreated magnesium was 0.4322 mm / year. This means that the color-treated magnesium has excellent corrosion resistance as compared with the untreated magnesium. From this, it can be seen that the color-treated magnesium according to the present invention has excellent corrosion resistance by forming a hydroxide film on the surface.

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Here, the kind of the hydroxide film according to the present invention is not particularly limited as long as it can scatter and refract the light incident on the surface, and specifically may be a magnesium hydroxide.

In one embodiment, the magnesium sample was immersed in a 10% aqueous solution of a solution at 100 DEG C, and after 80 minutes, 170 minutes, and 240 minutes, the composition of the hydroxide film formed on the surface was analyzed. As a result, it can be seen that the hydroxide film formed on the magnesium surface is magnesium hydroxide (Mg (OH) ₂ ).

In addition, the color-treated magnesium according to the present invention may further include a clear layer formed on the hydroxide film.

The clear layer may further include magnesium to improve the scratch resistance and durability of the surface. At this time, the clear coating agent for forming the clear layer is not particularly limited as long as it is a clear coating agent applicable to metal coating. More specifically, a matt clear coating agent or a glossy / matt clear coating agent applicable to a metal coating can be given.

The color-treated magnesium having the clear layer according to the present invention may have a clear layer peel ratio of 5% or less when the adhesion is evaluated after 72 hours of spray treatment at 35 ° C with 5% salt water.

Referring to FIG. 11, when a cross-cut tape test method was performed after 72 hours of spraying 5% saline solution at 35 ° C on a magnesium-coated colorless matte having a matte or glossy / lightless clear layer according to the present invention, It is confirmed that the area of the clear layer is 5% or less as compared with the total area of the specimen.

From these results, it can be seen that the magnesium in which the clear layer according to the present invention is formed has excellent adhesion between the magnesium-colored layer and the clear layer.

Further, in one embodiment, the present invention provides a magnesium color processing treatment method comprising the step of immersing magnesium in a hydroxide solution.

In the magnesium coloring treatment method, a color can be realized by immersing magnesium in a hydroxide solution to form a hydroxide film as a chromogenic film on the surface.

The hydroxide solution applicable to the hydroxide solution according to the present invention is not particularly limited as long as it is a solution containing a hydroxyl group (-OH group). More specifically, a solution in which at least one member selected from the group consisting of NaOH, KOH, Mg (OH) ₂ , Ca (OH) ₂ and Ba (OH) ₂ is dissolved can be used.

Referring to FIGS. 1 and 2, it can be confirmed that the magnesium using NaOH solution has a high color development speed, strong color, and a uniform magnesium surface in order to realize the same color. However, in the case of magnesium using distilled water, the color development speed is four times slower than that in the case of using NaOH solution, the color development is weak, and the surface of magnesium is not uniform.

From these results, it can be seen that when a hydroxide solution such as a NaOH solution is used as the hydroxide solution, the hydroxide film is formed rapidly on the magnesium surface, the color is developed at a faster rate, and the surface is uniform.

In the magnesium coloring treatment method according to the present invention, the concentration of the hydroxide solution may be 1% to 40%, more specifically 5% to 20%. In addition, the hydroxide solution may be run at a temperature ranging from 90 占 폚 to 200 占 폚, more specifically from 100 占 폚 to 150 占 폚, and still more specifically from 95 占 폚 to 110 占 폚. In addition, the color development treatment time can be performed for 1 minute to 500 minutes, specifically 10 minutes to 90 minutes. It is possible to economically realize various colors on the magnesium surface in the range of the magnesium coloring treatment conditions and to prevent the intrinsic gloss of magnesium from decreasing due to the increase in the thickness of the hydroxide film.

Referring to FIGS. 7 and 8, it can be seen that the thickness of the hydroxide film formed on the magnesium surface increases according to the elapsed time of the coloring treatment of magnesium, and the color developed is changed. This means that the color developed by the hydroxide film changes depending on its thickness. Accordingly, the color developed on the magnesium surface can be controlled by adjusting the rate of formation of the hydroxide film through the concentration, temperature, and color development treatment time of the hydroxide solution in which magnesium is immersed.

In addition, the magnesium color developing treatment method according to the present invention may further include: electrolytic degreasing using an alkaline cleaning liquid before the step of immersing magnesium in a hydroxide solution; And

After the step of immersing the magnesium in the hydroxide solution, the step of rinsing may further include at least one of the steps.

The electrolytic degreasing step is a step of electrolytically degreasing the magnesium surface with an alkaline cleaning liquid before the magnesium is immersed in the hydroxide solution, thereby cleaning the contaminants on the magnesium surface. At this time, the alkaline cleaning liquid is not particularly limited as long as it is commonly used for cleaning the surface of the metal.

In addition, the step of rinsing is a step of removing the hydroxide solution remaining on the magnesium surface by rinsing the magnesium surface after the step of immersing the magnesium in the hydroxide solution. In this step, by removing the hydroxide solution remaining on the magnesium surface, it is possible to prevent the formation of additional hydroxide film by the residual hydroxide solution.

Meanwhile, in the magnesium color development treatment method according to the present invention, the step of immersing the magnesium in the hydroxide solution comprises:

A first immersion step in which magnesium is immersed in a M ₁ concentration hydroxide solution; And

Magnesium, and includes a first n dipping immersing in a hydroxide solution of a concentration of M _n,

In the first and nth immersion steps, the concentration of the hydroxide solution may independently be independently selected from the following formulas (2) and (3), and n is an integer from 2 to 6:

&Quot; (2) &quot;

8? M ₁ ? 25

&Quot; (3) &quot;

M _n-1 -M _n &_gt; 3

In equations (2) and (3)

M ₁ and M _n denote concentration of the hydroxylated solution in each step, and the unit is%.

Further, in the magnesium color development treatment method according to the present invention, the step of immersing the magnesium in the hydroxide solution includes:

A first immersion step in which magnesium is immersed in a M ₁ concentration hydroxide solution; And

And a second immersion step in which magnesium is immersed in a M ₂ concentration hydroxide solution,

In the first and second immersion steps, the concentration of the hydroxide solution can be independently performed by a method satisfying the following conditions (4) to (6):

&Quot; (4) &quot;

8? M ₁ ? 25

&Quot; (5) &quot;

1.5? M _2? 15

&Quot; (6) &quot;

M ₁ -M ₂ > 5

In Equations 4 to 6,

M ₁ and M ₂ denote concentration of the hydroxide solution in each step, and the unit is%.

As described above, the step of immersing in the hydroxide solution according to the present invention is a step of embodying the color on the magnesium surface. At this time, the color developed on the magnesium surface can be controlled by controlling the thickness of the formed hydroxide film, and the thickness of the hydroxide film can be controlled according to the concentration of the hydroxide solution. Therefore, when the concentration of the hydroxide solution for immersing magnesium is M ₁ to M _n , specifically M ₁ to M ₆ ; M ₁ to M ₅ ; M ₁ to M ₄ ; M ₁ to M ₃ ; Or M &_lt; ₁ &gt; to M &lt; ₂ &_gt;, and submerged sequentially can control the fine chromaticity difference of hue realized on the surface.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the present invention is not limited to the following Examples and Experimental Examples.

Example 1

A 1 cm X 1 cm magnesium specimen was immersed in an alkaline cleaning solution and degreased. The degreased specimen was immersed in a 10% NaOH solution at 100 ° C for 40 minutes. Thereafter, the specimen was rinsed with distilled water and dried in a drying oven to prepare a color-treated magnesium specimen.

Example 2

The procedure of Example 1 was repeated except that the magnesium specimen was immersed for 30 minutes instead of immersing in a 10% NaOH solution at 100 ° C for 40 minutes to prepare a magnesium color-treated magnesium specimen .

Example 3

A magnesium specimen having a purple color was prepared by carrying out the same procedure as in Example 1 except that the magnesium specimen was immersed for 55 minutes instead of immersing the magnesium specimen in 100% of NaOH solution for 40 minutes .

Example 4

The procedure of Example 1 was repeated except that the magnesium specimen was immersed in a 10% NaOH solution for 40 minutes instead of immersing the magnesium specimen for 100 minutes in the same manner as in Example 1, thereby preparing a green color-treated magnesium specimen .

Example 5

A 1 cm X 1 cm magnesium specimen was immersed in an alkaline cleaning solution and degreased. The degreased specimen was immersed in a 10% NaOH solution at 100 ° C for 50 minutes. Thereafter, the specimen was rinsed with distilled water and dried. Then, the dried magnesium specimen was oven-dried at 120 ° C to 150 ° C using a matt-clear coating material in a liquid state to perform clear coating to obtain a matte magnesium- . At this time, the thickness of the coated matt clear is 5 占 퐉 or less.

Example 6

Except that the magnesium specimen in Example 5 was immersed for 85 minutes instead of immersing in a 10% NaOH solution at 100 ° C for 50 minutes to prepare a matrically clear coated magnesium chromate specimen .

Example 7

The procedure of Example 5 was repeated, except that the gloss / clear coating composition was used in place of the matting clear coating agent in Example 5 to prepare a glossy / colorless clear coated magnesium chromate specimen.

Comparative Examples 1 to 3

The procedure of Example 2 was repeated except that the magnesium specimen in Example 2 was immersed in distilled water at 100 ° C for the time shown in Table 1 instead of immersing the magnesium specimen in 100 ° C and 10% NaOH solution for 40 minutes Thereby preparing a color-treated magnesium test piece.

Immersion time Comparative Example 1 40 minutes Comparative Example 2 1 hours Comparative Example 3 2 hours

Experimental Example 1. Evaluation of Physical Properties of Color-Treated Magnesium by Different Types of Hydroxyl Solutions

The following experiment was conducted to evaluate the physical properties of the color-treated magnesium according to the type of the solution used as the hydroxide solution.

The hue of the color-treated magnesium specimens prepared in Example 1 and Comparative Examples 1 to 3 was visually evaluated, and the surface of each specimen was evaluated by scanning electron microscope. In the specimens of Examples 2 to 4 and Comparative Example 3, arbitrary three points, A to C, were selected, and the color coordinates of the selected points were measured to obtain the color coordinate deviations. At this time, the color coordinate deviation (? E) was derived using the following Equation (7), and the results are shown in Table 2 below.

&Quot; (7) &quot;

Any point L * a * b * Δ L * Δ a * Δ b * Δ E * Example 2-A 66.92 6.04 28.96 - - - - Example 2-B 66.98 5.81 28.97 -0.06 0.23 -0.01 0.237908 Example 2-C 66.92 5.73 29.17 0 0.31 -0.21 0.374433 Example 3-A 47.66 7.67 -1.88 - - - - Example 3-B 47.61 8.02 -1.42 0.05 -0.35 -0.46667 0.58547227 Example 3-C 47.59 8.11 -1.43 0.07 -0.44 -0.45 0.6296476 Example 4-A 57.82 -5.44 25.18 - - - - Example 4-B 57.84 -5.35 25.56 -0.02 -0.09 -0.38 0.391024 Example 4-C 57.58 -5.17 25.15 0.24 -0.27 0.03 0.271662 Comparative Example 3-A 44.58 7.46 20.13 - - - - Comparative Example 3-B 42.33 8.47 17.02 2.25 -1.01 3.11 3.919018 Comparative Example 3-C 41.7 8.25 16.9 2.88 -0.79 3.23 4.399023

First, referring to FIG. 1, it can be seen that the specimen having the magnesium surface treated with the NaOH solution as the hydroxide solution has a faster color development rate than the specimen using the distilled water as the hydroxide solution. More specifically, the specimen of Example 1 treated with NaOH solution was confirmed to be silver-colored at the time when the immersion elapsed time was 10 minutes, and then it was confirmed to be orange-colored within 40 minutes via gold color. However, in Comparative Examples 1 to 3 treated with distilled water, the specimen of Comparative Example 1, in which the immersion elapsed time was 40 minutes, had a slight change in color development and thus showed no significant difference in color from the colorless untreated magnesium. In addition, the specimen of Comparative Example 2, in which the immersion elapsed time was 1 hour, was gradually developed to develop a yellow color, and the specimen of Comparative Example 3 in which immersion for 2 hours had elapsed was found to be colored gold.

Next, referring to FIG. 2, it can be seen that the surface of the magnesium specimen subjected to the color development treatment using the hydroxide solution containing NaOH is uniform. More specifically, the specimen of Example 1 which had undergone color development with a 10% NaOH solution had a generally uniform surface. However, in the case of the specimens of Comparative Examples 1 to 3 in which distilled water was used to treat the magnesium surface, it was confirmed that the magnesium surface was not uniform.

Next, referring to FIG. 3 and Table 2, it can be seen that the magnesium specimen color-developed with the NaOH solution has a uniform color tone. More specifically, the specimen of Example 2 subjected to the color development treatment with NaOH solution has color coordinate deviations of ΔL <0.06, 0.23≤Δa <0.31, 0.01≤Δb <0.21 and 0.237≤ΔE < Respectively. Also in the specimens of Examples 3 and 4, it was confirmed that the deviation of the chromaticity coordinate deviations was not large as 0.02? DELTA L <0.24, 0.09 DELTA a <0.44, 0.03 DELTA b <0.47 and 0.271 DELTA E <0.630. However, in the specimen of Comparative Example 3, the color coordinate deviations were large in the color coordinate deviations of 2.25? DELTA 2.88, 0.79 DELTA a <-1.01, 3.11 DELTA b <3.23, and 3.919 DELTA E <4.40.

From this, the color development processing of magnesium according to the invention are hydroxide solution, such as distilled water by color development processing of magnesium hydroxide solution, or the like NaOH, KOH, Mg (OH) 2, Ca (OH) 2, Ba (OH) 2 It can be seen that the color is uniformly realized within a short period of time as compared with the color-treated magnesium. Further, the surface of the magnesium-treated magnesium is also homogeneous, so that magnesium is excellent in texture.

EXPERIMENTAL EXAMPLE 2 Evaluation of color development of magnesium according to immersion time of a hydroxide solution

The following experiment was conducted to evaluate the degree of color development according to the immersion time of the magnesium hydroxide coloring solution according to the present invention.

A 1 cm X 1 cm magnesium specimen was immersed in an alkaline cleaning solution and degreased. The degreased specimen was immersed in a 10% NaOH solution at 100 ° C for 240 minutes. At this time, immediately after immersing the magnesium specimen in the NaOH solution, the color of the specimen was visually evaluated at intervals of 5 to 10 minutes. In order to confirm the state of the hydroxide film formed on the surface, analysis of the surface components of the color - treated specimen, transmission electron microscope and scanning electron microscope were performed at 80 minutes, 170 minutes and 240 minutes after dipping. The results are shown in FIG. 7 and FIG.

Referring to FIG. 7, it can be seen that the chromogenic film component formed on the magnesium surface is magnesium hydroxide (Mg (OH) ₂ ), and the thickness of the film increases as the immersion time in the hydroxide solution becomes longer have. More specifically, as a result of examining the composition of the chromogenic film on the specimen after 80 minutes, 170 minutes and 240 minutes after immersing the magnesium specimen in the hydroxide solution, the components of the chromogenic film were magnesium hydroxide (Mg (OH) ₂ ). Further, it can be seen that the thickness of the magnesium hydroxide coating increases with the passage of time at 400 nm, 700 nm and 800 nm, respectively.

Next, referring to FIG. 8, it can be seen that the color-developed magnesium is colored in various colors depending on the immersion time in the hydroxide solution. More specifically, when a silver-colored magnesium specimen which has not undergone coloring treatment is immersed in a hydroxide solution, the color is sequentially colored with gold, red, purple, indigo and green as time elapses, and the color developed is repeated with a constant cycle appear.

From this, it can be seen that the color-treated magnesium according to the present invention is colored by the magnesium hydroxide (Mg (OH) ₂ ) coating formed through the immersion of the hydroxide solution. Also, as the immersion time passes, the thickness of the coating formed on the surface increases, and various colors can be realized by changing the thickness of the coating depending on the immersion condition.

Experimental Example 3 Evaluation of Corrosion Resistance of Color-Treated Magnesium 1

In order to evaluate the corrosion resistance of the color-treated magnesium according to the present invention, the following experiment was conducted.

1 cm x 1 cm of the untreated magnesium specimen and the magnesium specimen colored in Example 4 were subjected to a salt water concentration test using a salt spray tester (SST, Salt Spray Tester) at a salt concentration of 5% and a salt water having a temperature of 35 ° C The surface of the sheet material after the elapse of 942 hours was visually evaluated. The results are shown in Fig.

Referring to FIG. 9, it can be seen that the corrosion resistance of the specimen of Example 4 is remarkably improved. More specifically, the untreated magnesium specimens were found to be deformed because of the corrosion due to salt water, and the surface of the plate was not uniform even by the naked eye. On the other hand, in the case of the specimen subjected to the color development treatment in Example 4, only a slight degree of discoloration proceeded, and the surface of the plate was not deformed.

From this, it can be seen that the magnesium color-treated according to the present invention is improved in the corrosion resistance of magnesium due to the magnesium hydroxide formed on the surface thereof.

Experimental Example 4 Evaluation of Corrosion Resistance of Color-Treated Magnesium 2

In order to evaluate the corrosion resistance of the color-treated magnesium according to the present invention, the following experiment was conducted.

The chrome-treated magnesium specimens were immersed in a 1 cm X 1 cm colorless untreated magnesium specimen and 100 ° C and 10% NaOH solution for 75 minutes, 150 minutes, and 230 minutes, respectively. At the end of the time, two specimens were subjected to a coaxial polarization test. The resultant measured coercive polarization curves are shown in Fig. 10, and the coercive current density (I _corr ) obtained in the tapel area (± 200 mV) of the polarization curve of the magnesium specimens was measured by Tafel analysis ), Corrosion potential (E _corr ) and formal potential (E _pit ). Corrosion rate (Corr. Rate) was also calculated from the values derived using the following equation (8). The results are shown in Table 3 below.

&Quot; (8) &quot;

Where E.W is the magnesium atomic weight / exchange electron number = 24.305 / 2;

The density is 1.738 g / cm &lt; ^{3 &} gt ;.

Colorless untreated specimen Color-treated specimen 75 minutes 150 minutes 230 minutes I _corr (μA / cm ² ) 19.298 0.055 0.025 0.019 E _corr (V _SCE ) -1,492 -1.328 -1.318 -1.481 E _pit (V _SCE ) - -1.135 -1.180 -1.437 E _corr - E _pit (V) - 0.193 0.138 0.044 Corrosion resistance (mm / yr) 0.4322 0.0013 0.0006 0.0004

As shown in Table 3, it can be seen that the color-treated magnesium according to the present invention has improved corrosion resistance.

More specifically, as a result of the electrodischarge poling test on the untreated magnesium specimens and the magnesium specimens subjected to color development for 75 minutes, 150 minutes and 230 minutes, the color-treated specimens exhibited a corrosion resistance of 0.0004 to 0.0013 mm / yr (Corr. Rate), and it was confirmed that the longer the color development time, the lower the corrosion rate. On the other hand, in the case of the uncoloured specimen, the corrosion rate was 0.4322 mm / yr, and the corrosion rate was about 330 times higher than that of the color-treated specimen. This means that the color-treated magnesium according to the present invention inhibits corrosion by forming a hydroxide film on the magnesium surface.

Accordingly, it can be seen that the corrosion resistance of the magnesium color-treated according to the present invention is improved by the hydroxide film formed on the surface.

EXPERIMENTAL EXAMPLE 5. Evaluation of Physical Properties of Color-Treated Magnesium Having a Clear Layer

The following experiment was conducted to evaluate the corrosion resistance and the adhesion of the color-treated magnesium having the clear layer according to the present invention.

The color-treated magnesium prepared in Examples 5 and 7 was subjected to the same conditions as those in Experimental Example 3, but sprayed with brine, after 72 hours, the surface corrosion resistance and color development The adhesion between the treated magnesium and the clear layer was evaluated. At this time, the adhesion was evaluated by a cross-cut tape test method. More specifically, the coated clear layer was cut using a knife so as to cross each of 6 horizontal lines and 6 vertical lines at intervals of 1 mm. Thereafter, the tape was firmly attached to the intersection of the horizontal line and the vertical line, and the peeling area of the thin film relative to the entire area of the sample at the time of fast peeling was evaluated. The results are shown in Fig.

Referring to FIG. 11, it can be seen that the color-treated magnesium in which the clear layer is formed has excellent corrosion resistance and excellent adhesion between magnesium and the clear layer. More specifically, the specimens of Examples 5 and 7, in which a matte or glossy / non-matte clear layer was formed, were found to be salty fountain and showed no surface deformation due to corrosion even after 72 hours.

Further, as a result of the adhesion test between the magnesium layer and the clear layer subjected to the color development treatment with respect to the specimen on which the surface corrosion test was performed, it was confirmed that the area of the clear layer peeled off to the tape was 5% or less of the total area.

From this, it can be seen that the color-developed magnesium having a clear layer has improved corrosion resistance against salt water, and the adhesion between the clear layer and the magnesium subjected to color development is excellent.

Therefore, magnesium in the magnesium color development processing method according to the present invention is a short period of time, by the immersion of the magnesium hydroxide solution, or the like NaOH, KOH, Mg (OH) 2, Ca (OH) 2, Ba (OH) 2 color development processing The hydroxide film can be uniformly formed. Further, the color-treated magnesium thus produced can be uniformly realized in various colors by controlling the thickness of the hydroxide coating. Further, the surface of the chromogenic magnesium can be homogeneous, and the inherent texture and corrosion resistance of magnesium can be improved.

Claims (14)

Magnesium matrix; And a hydroxide film formed on the surface of the magnesium matrix,
For a magnesium specimen of 1 cm in width and 1 cm in length,
The color coordinate deviations (ΔL, Δa, Δb) for any three points present on the specimen satisfy the conditions of at least one of ΔL <0.6, Δa <0.6 and Δb <0.5.
The method according to claim 1,
And the thickness of the hydroxide film is 50 nm to 2 占 퐉.
The method according to claim 1,
With respect to the magnesium specimen subjected to color development treatment,
Color-treated magnesium satisfying the following formula (1): &lt; EMI ID =
[Equation 1]
Corrosivity (Corr. Rate) ≤0.01
Corrosion Rate (Corr. Rate) in the above equation means the degree of corrosion according to the electroconductive polarization test in the 0.5% NaCl solution at room temperature for the chromogenic magnesium,
The unit is mm / year,
The concentration unit% of the NaCl solution represents the weight percentage of NaCl dissolved in the NaCl solution.
delete The method according to claim 1,
The hydroxide film is a magnesium hydroxide, which is a color-treated magnesium.
The method according to claim 1,
A color-treated magnesium further comprising a clear layer formed on the hydroxide film.
The method according to claim 6,
The color-developed magnesium having the clear layer formed thereon,
After 72 hours of treatment at 35 占 폚 and 5% brine,
The degree of peeling of the clear layer is 5% or less,
The salt concentration unit% represents the weight percentage of the salt dissolved in the brine.
Immersing magnesium in a hydroxide solution to form a hydroxide film on the surface,
Wherein the immersion is carried out in a 90 DEG C to 200 DEG C aqueous solution for 1 minute to 500 minutes.
9. The method of claim 8,
Wherein the hydroxide solution comprises at least one selected from the group consisting of NaOH, KOH, Mg (OH) ₂ , Ca (OH) ₂ and Ba (OH) ₂ .
9. The method of claim 8,
In the step of immersing magnesium in the hydroxide solution,
The concentration of the hydroxide solution is 1% to 40%
Wherein the concentration unit% represents the weight percentage of the hydroxide dissolved in the hydroxide solution.
delete 9. The method of claim 8,
Prior to the step of immersing the magnesium in the hydroxide solution,
Electrolytic degreasing using an alkaline cleaning liquid; And
After the step of immersing the magnesium in the hydroxide solution, the step of rinsing
Wherein the method further comprises at least one of the following steps.
9. The method of claim 8,
The step of immersing the magnesium in the hydroxide solution comprises:
A first immersion step in which magnesium is immersed in a M ₁ concentration hydroxide solution; And
Magnesium, and includes a first n dipping immersing in a hydroxide solution of a concentration of M _n,
In the first and nth immersion steps, the concentration of the hydroxide solution independently satisfies the following equations (2) and (3), and n is an integer of 2 or more and 6 or less:
&Quot; (2) &quot;
8? M ₁ ? 25
&Quot; (3) &quot;
M _n-1 -M _n &_gt; 3
In equations (2) and (3)
M ₁ and M _n denote the concentration of the hydroxide solution in each step,
The units are percentages representing percentages by weight of hydroxides dissolved in the hydroxide solution.
9. The method of claim 8,
The step of immersing the magnesium in the hydroxide solution comprises:
A first immersion step in which magnesium is immersed in a M ₁ concentration hydroxide solution; And
And a second immersion step in which magnesium is immersed in a M ₂ concentration hydroxide solution,
In the first and second immersion steps, the concentration of the hydroxide solution independently satisfies the following conditions (4) to (6):
&Quot; (4) &quot;
8? M ₁ ? 25
&Quot; (5) &quot;
1.5? M _2? 15
&Quot; (6) &quot;
M ₁ -M ₂ > 5
In Equations 4 to 6,
M ₁ and M ₂ denote concentrations of the hydroxide solution in each step,
The units are percentages representing percentages by weight of hydroxides dissolved in the hydroxide solution.

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