JPH062960B2 - Electrolytic coloring method for chromium alloys - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for electrolytically coloring a chromium alloy, and more particularly to a method for electrolytically coloring the side surface of a columnar chromium alloy such as a column.

(Prior Art) A conventional method for electrolytically coloring a chromium alloy is disclosed in, for example, Japanese Patent Publication No.
No. 32621. In this method, a stainless steel as a chromium alloy and an electrode are immersed in a solution containing chromic acid and sulfuric acid at intervals, and anodic electrolytic treatment is performed on the stainless steel to form a porous film on the surface of the stainless steel. , Is a method of coloring.

(Problems to be Solved by the Invention) When such a conventional electrolytic coloring method is used to color the side surface of, for example, a cylindrical chromium alloy, uneven coloring occurs on the side surface. Because, in the conventional electrolytic coloring method, since the distance from each part on the side surface of the cylindrical chromium alloy to the counter electrode is different, the current density of each part on this side surface is also different. The amount of electricity per unit area given to each part also differs. Then, due to the difference in the amount of electricity per unit area, uneven coloring occurs on the side surface of the chromium alloy.

Therefore, a main object of the present invention is to provide an electrolytic coloring method for a chromium alloy, which enables electrolytic coloring without uneven coloring on the side surface of a columnar chromium alloy.

(Means for Solving Problems) The present invention is a method of electrolytically coloring a columnar chromium alloy to electrolytically color the side surfaces of the chromium alloy, which is a solution containing a chromium compound and sulfuric acid. , A step of placing the electrode in the solution, a step of facing the electrode in the solution, the chromium alloy, so that its central axis is parallel to the electrode, and the chromium alloy, It is an electrolytic coloring method for a chromium alloy, which includes a step of rotating with a central axis as a rotation axis, and a step of rotating the chromium alloy in a step of rotating the chromium alloy, and at the same time, performing anodizing electrolysis of the chromium alloy.

(Function) When performing anodic electrolysis on the chromium alloy, the columnar chromium alloy facing the electrode is rotated with its central axis as the rotation axis.
The amount of electricity per unit area can be given uniformly.

(Effects of the Invention) According to the present invention, since the same amount of electricity per unit area can be given to each part on the side surface of the columnar chromium alloy, the side surface of the chromium alloy can be electrolytically colored without uneven coloring. You can

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

(Embodiment) In this embodiment, a method of electrolytically coloring the side surface of a workpiece made of, for example, a stainless steel hollow cylinder, which will be the body of a thermos bottle, will be described as an example. First, in order to carry out the present invention. An example of the electrolysis device will be described in detail.

FIG. 1 is an illustrative view showing one example of an electrolysis device for carrying out the present invention. This electrolysis device 10 includes a constant current power source 12
This constant current power supply 12 outputs an arbitrary constant current from its output end by connecting a power supply of AC 100 to 200 V, for example, to its input end. In addition,
The constant current power supply 12 can output a DC constant current having an arbitrary current value of, for example, 0 to 10 A. For example, a conductor having a current passage area of 1 dm ² can output 0 to 10 A / d.
A current having a current density of m ² can be passed.

One output end of the constant current power supply 12 is connected to a conductive holder 18 via an ammeter 16 for digital display or analog display, for example. Further, the holder 18 holds a hollow cylindrical workpiece 20 made of stainless steel.
Therefore, one output end of the constant current power supply 12 is connected to the work piece 20 via the ammeter 16 or the like.

The workpiece 20 may be made of a chromium alloy other than stainless steel, and may have a solid polygonal columnar shape or a bottomed shape. Of course, the point is that it should be a columnar one made of a chromium alloy.

Further, it is desirable that this work piece 20 be subjected to a treatment such as a degreasing treatment, a water washing treatment and a neutralization treatment as a pretreatment for the electrolytic coloring treatment. This degreasing treatment is performed by immersing the workpiece 20 in a solution of, for example, a sodium orthosilicate system at 70 ° C. The washing process is performed by ultrasonically cleaning the work piece 20 in a water tank, for example. Further, the neutralization treatment is performed by immersing the work piece 20 in a 20% HNO ₃ solution for 60 seconds, for example.

Further, in the holder 18, the transmission 2 is provided at the center of the upper portion corresponding to the central axis of the work piece 20 via the rotary shaft 18a or the like.
Connected to 1. Further, the transmission 2 has a motor 2
2 are connected. Therefore, by driving the motor 22, the workpiece 20 can be rotated with its central axis as the rotation axis, and the number of rotations required by the transmission 21 can be obtained.

On the other hand, the other output end of the constant current power supply 12 is connected to a counter electrode plate 24 as an electrode. This counter plate 24 is made of lead in this embodiment, but is made of platinum, titanium, niobium,
It may be formed of other conductive materials such as carbon and stainless steel.

The work piece 20 and the counter electrode plate 24 are arranged in the solution 28 in the solution tank 26 so as to face each other at a predetermined interval. In this case, the workpiece 20 and the counter electrode plate 24 are arranged so that the central axis of the workpiece 20 is parallel to the counter electrode plate 24.

That is, in this embodiment, the solution tank 26 is formed so that the inner volume thereof is, for example, 250, and 200 solutions 28, for example, are stored in the solution vessel 26. Then, the workpiece 20 and the counter plate 24 are
They are immersed in the solution 28 so as to face each other.

In order to improve the processing efficiency, as shown in FIG. 2, a counter electrode plate 24 and a counter electrode plate 25 may be provided on both sides of the work piece 20.

The upper portion of the holder 18 and the work piece 20 has a solution 28
It is arranged so as not to be pickled. However, if the holder 18 is made of a metal material such as titanium or stainless that is not easily corroded by the solution 28, the holder 18 or the like may be dipped in the solution 28.

Further, an inner material (not shown) is formed on the inner surface of the solution tank 26 of this embodiment by lining a conductive material such as lead, and the constant current power source 12 is formed on the inner material. By connecting the output ends, this interior material can be used as an electrode or an electrode plate.

The solution 28 stored in the solution tank 26 contains, for example, 250 g / chromic acid as a main component and 490 g / sulfuric acid as an electrolyte. As the main agent of the solution 28, a chromium compound such as chromate or dichromic acid can be used in addition to chromic acid.

As a preferred example of the solution 28 in the present invention, for example, a solution containing chromic acid in an amount of 50 to 500 g / and sulfuric acid in an amount of 300 to 1000 g / can be mentioned. That is, the chromic acid contained in the solution contains 50 g /
If it is less than 500, it takes too much time for electrolytic treatment for electrolytic color development, which is not practical, and if it exceeds 500 g /, it is economically disadvantageous. Therefore, the chromic acid contained in the solution 28 in the present invention is desirably contained within the above range. Furthermore, the sulfuric acid contained in the solution, when it is less than 300 g /
The reaction of electrolytic treatment is too slow to be practically useful.
When the value exceeds 0 g /, the surface of the chromium alloy as the workpiece is dissolved and a porous oxide film cannot be formed on the surface of the chromium alloy. Therefore, the sulfuric acid contained in the solution 28 in the present invention is However, it is desirable that the content be within the above range.

If the temperature of the solution 28 is lower than room temperature (20 ° C.), the electrolytic treatment takes too long to be put into practical use, and if it is higher than 100 ° C., the solution tank is deteriorated due to corrosion or the like. Since it occurs, it is desirable to set it in the range of 20 to 100 ° C. More preferably, the temperature of the aqueous solution is in the range of 40 ° C to 80 ° C, and most preferably, it is in the range of 50 to 60 ° C.

Further, in the solution 28, for example, an inhibitor such as phosphoric acid is added in an amount of, for example, 10 to 120 g / in order to suppress a rapid change in color due to electrolytic coloring and facilitate extraction of a constant color.
It may be contained.

Next, the step of electrolytically coloring the side surface of the work piece 20 with the electrolytic device 10 will be described in detail. First, as shown in FIG. 1, the work piece 20 and the counter electrode plate 24 are connected to the electrolysis apparatus 10, and the work piece 20 and the counter electrode plate 24 are arranged so as to face each other in the solution 28 in the solution tank 26. Soak. In this case, the work piece 20 is arranged so that its central axis is parallel to the counter electrode plate 24.

Then, the motor 22 is driven, whereby the workpiece 20 is rotated, for example, from 6 to 6 with the central axis thereof as the rotation axis.
Rotate at 10 rpm.

Next, a current is output from the constant current power source 12 and the solution tank 26
The workpiece 20 in the solution 28 therein, for example 5 to 1
Anodic electrolysis is performed for 5 minutes. During this anodic electrolysis process, the workpiece 20 is rotated with its central axis as the axis of rotation. At this time, considering a certain part on the side surface of the work piece 2, the distance between this part and the counter plate 24 is changed in a constant cycle with time because the work piece 20 is rotating. Similarly, with respect to the other part on the side surface of the work piece 20, the distance between the work piece 20 and the counter plate 24 is changed in a constant cycle. Therefore, the current density per unit area in each part on the side surface of the work piece 20 is also changed in a constant cycle with time. Therefore, the amount of electricity per unit area can be uniformly applied to the side surface of the work piece 20. That is, by rotating the work piece 20, it is possible to give an equal amount of electricity to all the parts on the side surface of the work piece 20. Therefore, an oxide film can be uniformly formed on the side surface of the work piece, and the electrolytic coloring can be uniformly performed.

In the above embodiment, the workpiece 20 was subjected to anodic electrolytic treatment to form an oxide film on the side surface of the workpiece 20, but in the present invention, the workpiece 20 is further processed.
The oxide film may be cured by subjecting it to cathodic electrolysis. In this case, the workpiece 20 may be subjected to the anodic electrolysis treatment and the cathodic electrolysis treatment in the solution 28 in the same solution bath 26. Further, the anodic electrolysis treatment and the cathodic electrolysis treatment may be alternately and repeatedly performed, for example, by using a current whose polarity is changed at regular intervals.

An experimental example in which a chromium alloy is electrolytically colored according to such steps will be described.

Experimental Example I A cylindrical stainless alloy (area to be colored ² dm ² ) was prepared as a workpiece, immersed in a sodium orthosilicate-based solution at 70 ° C., washed with water, and then immersed in a 20% HNO ₃ solution.
It was dipped for 0 seconds and washed again with water. In this way, the pretreated workpiece was treated with chromic acid 250 g / and sulfuric acid 490 g /
It was immersed in an aqueous solution of a liquid temperature 60 ° C., while rotating at a rotational speed 6 rpm 0.1 A / dm ² and 0.2 A / dm ² at a current density of 5 to 13 minutes, and anodic electrolysis. The sample thus obtained was examined for the presence of colored color and uneven coloring, and the results are shown in Appendix 1.

Experimental Example II A cylindrical stainless alloy (area to be colored 4 dm ² ) was prepared as a workpiece, and the same pretreatment as in Experimental Example I was performed. Chromic acid 250
It was immersed in an aqueous solution of g /, sulfuric acid 490 g /, and a liquid temperature of 60 ° C., and an anodic electrolysis treatment and a cathodic electrolysis treatment were repeatedly performed under the respective conditions shown in Table 2. The samples thus obtained were examined for the presence of colored color and uneven coloring, and the results are also shown in Appendix 2.

From Tables 1 and 2, it can be seen that according to the present invention, the columnar chromium alloy can be electrolytically colored without uneven coloring. Further, it can be seen from Appendix 1 and Appendix 2 that the current density and the treatment time can be determined by the color to be colored.

The lower limit of the rotation speed is theoretically at least 1 during processing.
Although it is a rotation, it is actually processing 2
It is preferable that the lower limit is 3 rotations. Further, the upper limit of the number of rotations is such that the workpiece is not shaken by the rotation, for example, although not shown as data in this embodiment, it is preferably about 100 rpm.

FIG. 2 is an illustrative view showing another example of the electrolysis apparatus for carrying out the present invention. In this electrolytic device 10, a plurality of holders 18 are provided on the conveyor 30 at intervals.
Each of the holders 18 is connected to a motor (not shown) via, for example, a transmission (not shown) and is rotated about its rotation axis. Therefore, the plurality of workpieces 20 held by each holder 18 are continuously moved in the solution 28 in the solution tank 26 while being rotated. In this case, the respective work pieces 20 undergo the same positional relationship as that of the counter electrode plate 24, and therefore, an equal amount of electricity is given to each work piece 20. Therefore, each work piece 20 can be colored with a constant color tone.

In this embodiment as well, it is needless to say that the work piece 20 may be alternately subjected to the anodic electrolysis treatment and the cathodic electrolysis treatment, for example, by using a current whose polarity is changed at regular intervals.

[Brief description of drawings]

FIG. 1 is an illustrative view showing one example of an electrolysis device for carrying out the present invention. FIG. 2 is an illustrative view showing a main part of another electrolysis apparatus for carrying out the present invention. FIG. 3 is an illustrative view showing another example of the electrolysis apparatus for carrying out the present invention. In the figure, 10 is an electrolysis device, 12 is a constant current power supply, and 16
Is an ammeter, 18 is a connector, 18a is a rotating shaft, 20 is a workpiece, and 22 is a motor.

Claims (6)

[Claims] 1. A method for electrolytically coloring a side surface of a chromium alloy by subjecting a columnar chromium alloy to an electrolytic treatment, the method comprising the steps of preparing a solution containing a chromium compound and sulfuric acid, wherein: Disposing an electrode, in the solution, the chromium alloy, so that the central axis is parallel to the electrode, facing the electrode, the chromium alloy, with the central axis as a rotation axis A method of electrolytically coloring a chromium alloy, comprising: rotating the chromium alloy in the step of rotating, and rotating the chromium alloy in the step of rotating the chromium alloy, and at the same time, subjecting the chromium alloy to an anodic electrolytic treatment. 2. The method for electrolytically coloring a chromium alloy according to claim 1, wherein the chromium compound contains one of chromic acid, chromate and dichromic acid. 3. The chromium alloy according to claim 1, further comprising rotating the chromium alloy in the step of rotating the chromium alloy and simultaneously subjecting the chromium alloy to cathodic electrolysis. Electrolytic coloring method. 4. The method according to claim 3, wherein the step of subjecting the chromium alloy to anodic electrolysis and the step of subjecting the chromium alloy to cathodic electrolysis are performed in the solution in one tank. Electrolytic coloring method for chromium alloys. 5. The chromium according to claim 3 or 4, wherein the step of subjecting the chromium alloy to an anodic electrolysis treatment and the step of subjecting the chromium alloy to a cathodic electrolysis treatment are alternately repeated. Electrolytic coloring of alloys. 6. The method according to claim 1, wherein the step of causing the chromium alloy to face the electrode is continuously performed while moving the chromium alloy in the solution.
Item 6. A method for electrolytically coloring a chromium alloy according to any one of items.