JP2002161376A - Magnesium alloy molded product and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnesium alloy molded article excellent in corrosion resistance and easy to recycle, a magnesium alloy molded article excellent in corrosion resistance and having color and easy to recycle, and a method for producing the same. SOLUTION: The magnesium alloy compact 1, an aluminum layer 2 formed on the surface of the magnesium alloy compact 1, a chemical conversion coating layer 3 formed on the surface of the aluminum layer 2, and a chemical conversion coating layer 3. And a transparent coating film 4 formed on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnesium alloy molded product used for an outer case of home electric appliances and the like, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of environmental protection, in place of plastic products which have been widely used in the past, no harmful substances are generated during use or incineration of waste, and they are easily decomposed in soil after disposal. For such applications, application of a molded article made of a magnesium alloy that is lightweight and easily decomposed in the soil is being studied.

Conventionally, this kind of magnesium alloy generally has low corrosion resistance and does not provide long-term sustained corrosion resistance even with ordinary coating. Therefore, in order to secure the corrosion resistance, usually a chromic acid treatment or the like is used. , Followed by painting for coloring and weather resistance. As a method not relying on the chemical conversion treatment, for example,
As described in JP-A-261-261, there has been proposed a method in which an aluminum layer is formed on the surface of a magnesium alloy compact and then colored by painting.

[0004]

However, in the above-mentioned conventional method, since corrosion resistance is ensured by painting and coloring is performed, and coloring is performed by painting, the coloring color depends on the type of paint. It is necessary to change the paint according to the change of the color to be performed, and therefore, different paint components such as pigments are used. As a result, at the time of recycling, there is a problem that an impurity component such as a pigment to be discharged is different, so that an impurity removing step becomes complicated.

Accordingly, an object of the present invention is to provide a magnesium alloy molded article which is excellent in corrosion resistance and is easily recycled, a magnesium alloy molded article which is excellent in corrosion resistance and has a color and is easily recycled, and a method for producing the same. I do.

[0006]

Means for Solving the Problems To solve the above problems, a magnesium alloy molded article of the present invention comprises a magnesium alloy molded article, an aluminum layer formed on the surface of the magnesium alloy molded article, and an aluminum layer. And a chemical conversion coating layer formed on the surface of the substrate.

According to the above construction, since the aluminum layer is formed on the surface of the magnesium alloy molded body, the corrosion resistance is enhanced by this. Further, since the chemical conversion coating layer is formed on the surface of the aluminum layer, the chemical conversion coating layer further increases the corrosion resistance. Corrosion resistance is enhanced. Moreover, the corrosion resistance of the magnesium alloy compact is given by the aluminum layer and the chemical conversion coating layer, and is not given by painting as in the past, so there is no need to remove impurities in the paint, and recycling is easy. .

[0008] In the invention described in claim 2, the chemical conversion film layer is a chemical conversion film layer that produces interference colors. According to the above configuration, since the color is given by the interference color of the chemical conversion coating layer, unlike the conventional coloring using a coloring material such as a pigment, there is no need to remove the coloring material such as a pigment, and the material is easily recycled. can do.

According to a third aspect of the present invention, in the above structure, the thickness of the aluminum layer is 0.1 to 500 μm.
m. According to the above configuration, since the thickness of the aluminum layer is set to 0.1 to 500 μm, the thickness is appropriate, and the corrosion resistance is enhanced by the aluminum layer without impairing the lightweight property which is an advantage of the magnesium alloy.

Further, in the invention according to a fourth aspect, in the above configuration, a transparent coating film is formed on a surface of the chemical conversion film layer. According to the above configuration, the chemical conversion film layer is protected by the transparent coating film, and the corrosion resistance and the weather resistance are enhanced.

Further, the first manufacturing method of the present invention comprises a step of forming a magnesium alloy, a step of forming an aluminum layer on the surface of the obtained magnesium alloy compact,
Subjecting the magnesium alloy compact having the aluminum layer formed thereon to a chemical conversion treatment to form a chemical conversion coating layer that produces interference colors on the surface of the aluminum layer.

According to the above configuration, it is possible to obtain a magnesium alloy molded article which is given a color and is excellent in corrosion resistance without using a coloring material. Still further, a second manufacturing method of the present invention includes a step of forming a joining plate composed of a magnesium alloy plate and an aluminum plate, a step of forming the joining plate, Forming a chemical conversion coating layer that produces interference colors on the surface of the plate.

According to the above-mentioned structure, a magnesium alloy molded article which is given a color and is excellent in corrosion resistance can be obtained without using a coloring material. Further, since a magnesium alloy plate and an aluminum plate are used, these can be used. Since it can be formed in advance, a magnesium alloy molded product having a predetermined thickness can be easily manufactured.

Further, the invention according to claim 7 is the above configuration, wherein a step of forming a transparent coating film on the surface of the chemical conversion film layer is added after the step of forming the chemical conversion film layer.

According to the above construction, the chemical conversion coating layer is protected by the transparent coating film, so that the corrosion resistance and the weather resistance are enhanced, and the interference color of the chemical conversion coating layer is not obstructed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a magnesium alloy molded product and a method for producing the same according to the present invention will be described below.

The magnesium alloy compact is molded by injection molding or die casting. Here, an example of molding by injection molding will be described. This injection molding includes a melting step of melting the magnesium alloy and a casting step of injecting the molten metal and pouring the molten metal into a mold. In this case, a conventional injection molding apparatus is used as an injection molding apparatus.

As shown in FIG. 1, for example, an injection molding apparatus 5 melts and mixes a magnesium alloy (for example, an alloy composed of magnesium and aluminum) A as a starting material to form a molten metal. An injection unit 6 for injecting this at high pressure, and a nozzle 6 of the injection unit 6
And a divided mold 7 in which a casting gap 70 having a desired shape is formed on the inner surface thereof in contact with the mold 0 and the molded body can be taken out. The split mold 7 includes a fixed mold 7a and a split mold 7b.

When performing injection molding using the injection molding apparatus 5, the split mold 7b is set on the fixed mold 7a, and the outlet of the nozzle 60 of the injection unit 6 is pressed against the injection port 7c of the fixed mold 7a for connection. I do. In this state, the magnesium alloy A is supplied from the hopper 61 to the cylinder 63 heated by the heater 62.
The molten metal B is melted and mixed with a screw 64 in a cylinder 63 to form a molten metal B. The molten metal B is rotated and heated while the screw 64 is retracted, and is transferred to the front of the cylinder 63 so as to be in front of the cylinder 63. A pool 65 is formed in the portion, and then the screw 64 is pressed and advanced by the pressing means 66 to inject the molten metal B into the casting gap 70 of the split mold 7 at a high speed. The molten metal B supplied into the casting gap 70 by injection is successively applied to the inner surfaces 71a, 71b of the casting gap 70.
Is cooled while being in contact with, and solidification proceeds in a fluid state. During this time, the screw 64 is pressed by the pressing means 66 until the molten metal B injected into the casting gap 70 is completely solidified.
, The molten metal B is pressurized and solidified and contracted while replenishing the molten metal B with the inner surface 7 of the casting gap 70.
1a and 71b. After complete solidification, the mold 7 is divided and the molded body is taken out and allowed to cool to obtain a molded body.

The inner surface 71a of the casting gap 70 of the mold 7,
As shown in FIG. 2, a release material R is previously applied to 71b as needed. For the release material R, for example, a waxy mixed material of a fatty acid ester is used, and the release material R is usually applied by using a casting gap 70 of the mold 7 in which the liquid release material R is opened using the spray nozzle 8. Inner surfaces 71a, 71b of
It is sprayed on and a release material film is formed after drying. By applying the release material R, seizure of the molded body on the mold 7 can be prevented and mold release can be facilitated.
In the case of die casting, a release material is applied as necessary.

When a release material is used, the release material is removed from the surface of the molded body by etching, blasting, surface grinding, etc. to form an aluminum layer in a later step, and the surface is cleaned. Is preferable.

Next, an aluminum layer is formed on the surface of the injection molded article. Since magnesium and its alloys are base materials in the electrochemical series, aluminum having a small potential difference is less likely to be electrolytically eroded and is an optimal material having excellent corrosion resistance.

In order to form an aluminum layer on the surface of the compact, a thin film forming method such as sputtering or vapor deposition is used. In order to form an aluminum layer by sputtering, for example, a sputtering apparatus as shown in FIG. 3 is used. The sputtering apparatus 9 includes a support 93 for rotatably supporting a target 92 in a vacuum chamber 91 and a holder 94 for rotatably holding the molded body 1 on which an aluminum layer is to be formed.

In the sputtering apparatus 9, the support 93
The surface of the compact 1 held by the holder 94 is irradiated with the plasma 95 generated from the rotating target 92 supported by the substrate 95. An aluminum layer having a thin film thickness of 1 to 500 μm is formed. At this time, in order to improve the adhesion between the molded body 1 and the aluminum layer, a condition in which the particle velocity of the plasma 95 by sputtering is as high as possible is adopted, and the temperature of the molded body 1 is also selected under the optimal condition. Is preferred.

As described above, when the compact 1 is held by the rotatable holder 94, the plasma 9 generated from the target 92 can be applied to the compact 1 having a complicated three-dimensional shape.
The atoms and particles contained in 5 spread around the entire surface, and aluminum layer 2 can be formed on the entire surface. In addition, an aluminum layer is formed on the back side of the molded body as needed.

Next, a chemical conversion coating layer is formed on the surface of the aluminum layer. Examples of the chemical conversion coating layer include a layer of an oxide such as alumina generated by a reaction between aluminum and an acid forming the aluminum layer, and a layer of alumite generated by a reaction between the aluminum and iron. , These layers have micropores. In order to form a chemical conversion coating layer with sufficient corrosion resistance, the thickness is 0.1 μm
The above is desirable, and the upper limit of the thickness is not particularly limited, but considering the productivity, the upper limit is preferably about 5 μm.

In order to obtain a chemical conversion film layer that produces interference colors, a transparent film such as alumina is formed and its thickness is adjusted so as to be at least の of the wavelength of visible light. Then, a desired color can be obtained by changing the thickness of the chemical conversion coating layer to various thicknesses.

In the interference color, light reflected on the surface of the aluminum layer and light reflected on the surface of the chemical conversion coating layer interfere with each other, and the color is visually recognized as an interference color. The chemical conversion coating layer is obtained, for example, by immersing the molded article 1 on which the aluminum layer is formed in a treatment liquid 11 such as an acid in a chemical conversion treatment tank 10 as shown in FIG.

The molded article on which the chemical conversion coating layer has been formed may be used as a molded article as it is, but it is preferable to form a transparent coating film on its surface in order to further improve corrosion resistance and weather resistance.

To form a transparent coating film, for example, as shown in FIG.
A coating apparatus as shown in FIG. This coating device 20
In this method, a transparent paint is applied to the surface of the formed bodies 1 arranged on a transfer device 21 such as a belt conveyor by a spray 22 while being moved by the transfer device 21, and is baked in a drying furnace 23.

The molded article S obtained in this way is shown in FIG.
As shown in the figure, an aluminum layer 2,
A chemical conversion coating layer 3 and a transparent coating film 4 are sequentially formed. By adopting such a configuration, a molded product having corrosion resistance and color can be provided without impairing the lightness of the magnesium alloy.

Next, a description will be given of a second embodiment of the magnesium alloy molded product and the method for producing the same according to the present invention.
The second embodiment is different from the first embodiment in that a magnesium alloy plate formed in advance is used as a magnesium alloy compact, an aluminum plate is used as an aluminum layer, and a joint plate obtained by joining these is used. is there.

In order to manufacture a joined plate of a magnesium alloy plate and an aluminum plate, for example, a press as shown in FIG. 7 is used. The press device 30 shown in FIG.
A press plate 34a provided with a heater 33a and a press plate 34b provided with a heater 33b are arranged vertically. In this apparatus 30, a magnesium alloy plate 31 and an aluminum plate 32 whose surfaces have been cleaned are superimposed and heated by heaters 33a and 33b to a predetermined temperature between 200 ° C. and the melting point of the magnesium alloy. The bonding plate 35 is obtained by applying pressure at 34a and 34b.

Since magnesium (or its alloy) and aluminum can form a solid solution, if both are pressurized and joined under heating, a stronger joining becomes possible by a diffusion joining mechanism. The laminated structure of the joining plate 35 may be a structure in which the magnesium alloy plate 31 and the aluminum plate 32 are stacked one by one as described above, but a three-layer structure in which the aluminum plates 32 are laminated from both sides of the magnesium alloy plate 31. When it is set, a material having more excellent corrosion resistance can be obtained.

FIG. 8 shows a rolling apparatus of a rolling roll type capable of continuously manufacturing the above-mentioned three-layer structure bonding plate. In the rolling device 36, heating and pressurization by the rolls 37 a and 37 b are performed while simultaneously supplying the aluminum plates 32 and 32 from both sides of the magnesium alloy plate 31 while sandwiching the aluminum plates 32 and 32 between the heated rolls 37 a and 37 b. Thereby, the joining plate is manufactured continuously.

Next, the joining plate obtained as described above is formed into a predetermined shape. To form the joining plate,
For example, a press forming apparatus as shown in FIG. 9 is used.

The press forming apparatus 40 includes a heater 4
An upper die 43a composed of a molding die 42a provided with a molding die 1a and a lower die 4 composed of a molding die 42b provided with a heater 41b.
3b are arranged vertically. In this apparatus 10, for example, the bonding plate 35 having the three-layer structure is formed into a molding die 42.
When hot pressing is performed between a and the molding die 42b, a molded body having a predetermined shape is molded.

According to the press forming apparatus 40, the aluminum plates 32, 32 on the front side are the magnesium alloy plates 31.
Since the ductility is higher than that of the above, by setting the forming conditions suitable for the magnesium alloy, a good joining plate 35 can be obtained.
Is obtained. The shape of the formed joining plate 35 is a flat plate according to the press forming apparatus 40, but it can be formed into a three-dimensional shape by forging.

The formed body composed of the magnesium alloy plate and the aluminum plate obtained as described above is formed with a conversion coating layer and a transparent coating film on its surface in the subsequent steps in the same manner as in the first embodiment. Is done.

According to the second embodiment, since an aluminum plate formed in advance is used, a thicker aluminum layer can be obtained as compared with the first embodiment. For example, one having a thickness of about 0.5 mm can be easily obtained.

In the second embodiment, there is an advantage that the bonding plate can be prepared in advance as a standard material, which cannot be obtained in the first embodiment.

[0042]

As described above, according to the magnesium alloy molded article of the present invention, the corrosion resistance can be enhanced by the aluminum layer and the chemical conversion coating layer. Moreover, since the corrosion resistance is not given by coating, there is no need to remove impurities in the coating, and recycling is easy.

According to the second aspect of the present invention, the color is given by the interference color of the chemical conversion coating layer, which is different from the conventional coloring using a coloring material such as a pigment. It can be easily recycled without having to remove it.

According to the third aspect of the present invention, the corrosion resistance is enhanced by the aluminum layer without impairing the advantage of the magnesium alloy, that is, lightness. According to the fourth aspect of the present invention, the chemical conversion film layer is protected by the transparent coating film, and the corrosion resistance and the weather resistance are enhanced.

Further, according to the first production method of the present invention, it is possible to obtain a magnesium alloy molded article which is given a color and is excellent in corrosion resistance without using a coloring material.

Further, according to the second production method of the present invention, it is possible to obtain a magnesium alloy molded article which is given a color and is excellent in corrosion resistance without using a coloring material.

According to the seventh aspect of the present invention, the magnesium alloy is formed by protecting the chemical conversion film layer, thereby enhancing corrosion resistance and weather resistance, and furthermore, observing the interference color of the chemical conversion film layer. Goods are obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an injection molding apparatus for injection-molding a magnesium alloy compact according to the present invention.

FIG. 2 is a cross-sectional view of a mold showing a state of application of a release material in the above-described injection molding apparatus.

FIG. 3 is a cross-sectional view showing a sputtering apparatus for forming an aluminum layer according to the present invention.

FIG. 4 is a cross-sectional view showing a chemical conversion treatment tank for forming a chemical conversion coating layer in the present invention.

FIG. 5 is a schematic view showing a coating apparatus for forming a transparent coating film in the present invention.

FIG. 6 is a sectional view showing an example of a magnesium alloy molded product according to the present invention.

FIG. 7 is a schematic configuration diagram of a press device for manufacturing a bonding plate in the present invention.

FIG. 8 is a schematic configuration diagram of a rolling device for manufacturing a joined plate according to the present invention.

FIG. 9 is a schematic configuration diagram of a press forming apparatus for forming a bonding plate in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molded body 2 Aluminum layer 3 Chemical conversion coating layer 4 Transparent coating film 5 Injection molding device 6 Injection unit 7 Split mold 7a Fixed mold 7b Split mold 7c Injection port 8 Spray nozzle 9 Sputter device 10 Chemical conversion tank 11 Treatment liquid 12 Reference Signs List 20 coating device 21 transfer device 22 spray 23 drying furnace 30 press device 31 magnesium alloy plate 32 aluminum plate 33a, 33b heater 34a, 34b press plate 35 joining plate 36 rolling device 37a, 37b roll 40 press forming device 41a, 41b heater 42a, 42b Molding die 43a Upper die 43b Lower die 60 Nozzle 61 Hopper 62 Heater 63 Cylinder 64 Screw 65 Hot water pool 66 Pressing means 70 Casting gap 71a, 71b Inner surface of casting gap 91 Vacuum tank 92 Target 93 Support 94 Holder 95 Plasma A Magnesium alloy B Molten metal R Release material S Molded product

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K026 AA09 BA08 BB01 CA13 DA03 4K044 AA06 AB09 AB10 BA10 BA12 BA21 BB04 BB16 BC02 BC09 CA16 CA53

Claims (7)

[Claims] 1. A magnesium alloy molded article comprising: a magnesium alloy molded body; an aluminum layer formed on a surface of the magnesium alloy molded body; and a chemical conversion coating layer formed on a surface of the aluminum layer. . 2. The magnesium alloy molded article according to claim 1, wherein the chemical conversion coating layer is a chemical conversion coating layer that produces interference colors. 3. The magnesium alloy molded product according to claim 1, wherein the thickness of the aluminum layer is 0.1 to 500 μm. 4. The magnesium alloy molded product according to claim 1, wherein a transparent coating film is formed on the surface of the chemical conversion coating layer. 5. A step of forming a magnesium alloy, a step of forming an aluminum layer on the surface of the obtained magnesium alloy formed body, and a chemical conversion treatment of the magnesium alloy formed body having the aluminum layer formed thereon to form an aluminum layer. Forming a conversion coating layer that produces an interference color on the surface. 6. A step of forming a joining plate composed of a magnesium alloy plate and an aluminum plate, a step of forming the joining plate, and forming an interference color on the surface of the aluminum plate by subjecting the formed joining plate to a chemical conversion treatment. Forming a chemical conversion coating layer. 7. After the step of forming the chemical conversion coating layer,
7. The method for producing a magnesium alloy molded product according to claim 5, wherein a step of forming a transparent coating film on the surface of the chemical conversion coating layer is added.