JPH05125591A - Formation of black oxide film on copper wire - Google Patents

Abstract

PURPOSE:To stably and efficiently form a high-quality black oxide film on a copper wire for a long time. CONSTITUTION:A black oxide film is continuously formed on a copper wire 4 in an electrolyte 1. In this case, a copper ion removing anode 5 and a cathode 6 are arranged in the electrolyte 1, and copper ion is eluted from the wire 4, deposited on the cathode 6 and removed. Since the copper ion in the electrolyte 1 is removed in this way, the anodization voltage is appropriately set at all times, and a high-quality black oxide film is formed on the wire 4. Besides, the film is stably and efficiently formed for a long time without any manual work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire material such as a copper wire, a copper alloy wire, a copper-coated steel wire, a copper-stabilized superconducting wire, etc., at least the surface of which is made of copper or a copper alloy, and which has a high quality black color by an anodic oxidation method. The present invention relates to a method for stably and efficiently forming an oxide film.

[0002]

2. Description of the Related Art A black oxide film obtained by anodizing a copper wire has a function as an electric insulating layer although it is mild.
It is also effective as a base for electrical insulation coating. There is also a decorative effect. Thus, the method of continuously anodizing a copper wire is, for example, as shown in FIG. 2, by running a copper wire 4 in an electrolytic solution 1 and using this copper wire 4 as an anode, separately arranged for anodization. A predetermined voltage is applied to the cathode 3.

[0003]

However, when a black oxide film is formed on a long copper wire, anodic oxidation is continuously performed for a long time, so that the copper ions dissolved from the copper wire in the electrolytic solution are aged. As a result, the voltage between the copper wire of the anode and the cathode ring for anodic oxidation is reduced, and color unevenness occurs in the black oxide film, and this color unevenness is not only bad in appearance. The electric insulation was also inferior. For this reason, during operation, the properties of the black oxide film that is formed are observed, and when color unevenness occurs, labor is required to adjust the voltage each time, and the color unevenness part is removed as a defective product. Therefore, there is a problem that the product yield is reduced.

[0004]

The present invention has been made as a result of intensive studies in view of such a situation. The purpose of the present invention is to efficiently produce a high-quality black oxide film on a copper wire for a long time. It is to provide a method of forming. That is, the present invention is a method of continuously forming a black oxide film on a copper wire by an anodizing method in an electrolytic solution, by arranging a copper ion removing electrode in the electrolytic solution and eluting from the copper wire. It is characterized in that copper ions are deposited on the electrode and removed.

The method of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a principal part explanatory view showing an embodiment of an anodizing device used in the method of the present invention. A ring-shaped anodizing cathode 3 is provided on the copper wire inlet side of the electrolytic cell 2 filled with the electrolytic solution 1.
Are arranged in a line. A copper wire 4 is passed through the anodizing cathode 3 by applying a voltage between the copper wire 4 and the anodizing cathode 3, and a plate-shaped copper is provided on the outlet side of the copper wire 4 in the electrolytic cell 2. An ion removing anode 5 and a cathode 6 are arranged, and the cathode 6
The copper ions in the electrolytic solution 1 are deposited and removed on the top. The electrolytic solution 1 circulates between the electrolytic solution 1 and a storage tank 7 disposed below the electrolytic cell 2, and the liquid temperature is adjusted and the residue is filtered in the storage tank 7.

In the method of the present invention, the copper ion-removing electrode can be arranged at any position such as in the electrolytic cell or in the storage tank.
It is preferable to dispose the copper ion removing electrode as far as possible from the disposition position of the anodizing cathode because the anodizing conditions are not disturbed. Ordinary electrode materials such as SUS and platinum-coated titanium materials are applied to the anodizing cathode and the copper ion removing electrode. The cathode used for anodic oxidation is usually a ring-shaped or cylindrical one in order to uniformly anodize the surface of the copper wire in the circumferential direction. In the method of the present invention, between the anodizing cathode and the copper wire, a low voltage at which anodization starts at the beginning, a higher voltage at which an anodized film is formed in the middle, and finally formed Higher voltage is applied to improve the black oxide film. To apply such a voltage distribution using the same power supply, use multiple ring-shaped cathodes or cylindrical cathodes and arrange or arrange them so that their inner diameters gradually narrow in the longitudinal direction. Done. Further, the copper ion removing electrode is always used with a voltage applied, but the voltage may be applied intermittently.

[0007]

In the method of the present invention, the copper ions dissolved in the electrolytic solution from the copper wire to be anodized are removed by the copper ion removing electrode, so that the voltage between the copper wire and the anodizing electrode is always constant. The high-quality black oxide film is stably formed on the copper wire for a long time. Further, the voltage between the electrodes for removing copper ions may be set to a slightly higher value because it only deposits copper ions in the liquid, which saves the labor of voltage adjustment and is efficient.

[0008]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 A black oxide film was formed on a 3 mmφ copper wire using the anodizing apparatus shown in FIG. Use caustic soda as the electrolyte.
An aqueous solution containing 0 wt% was heated to 98 ° C and used. As the anodizing cathode, two SUS wire rods with a thickness of 6 mmφ were molded into a ring shape with an inner diameter of 100, 75, 50 mmφ, and two each were placed concentrically with an interval of 100 mm in order of increasing inner diameter. Used. For copper ion removal electrode
A pair of 100 × 200 mm SUS anode and cathode plates were used so as to face each other. Then, the copper wire of 3mmφ is 5m / mi
It was run in the liquid tank at a speed of n. A predetermined voltage was applied between this copper wire and the above-mentioned cathode ring for anodic oxidation to form a black oxide film on the copper wire. The power supply to the copper wire was performed by pressing the power supply roller in front of the inlet of the liquid tank. A current of 2 A was passed through the copper ion removing electrode.

Example 2 In Example 1, the electrode for removing copper ions was 500 × 300 m.
A black oxide film was formed on the copper wire by the same method as in Example 1 except that the anode plate and the cathode plate of m-plated titanium coated with m were used so as to face each other in the storage tank. Comparative Example 1 A black oxide film was formed on a copper wire by the same method as in Example 1 except that the conventional anodizing apparatus shown in FIG. 2 was used. The anodic oxidation conditions and the quality of the black oxide film in the above Examples or Comparative Examples were investigated. The results are shown in Table 1.

[0010]

[Table 1]

As is clear from Table 1, in the method products of the present invention (Examples 1 and 2), a high-quality oxide film having no color unevenness was stably formed over a long period of time. In particular, in the case where the electrode for removing copper ions was arranged in the storage tank (Example 2), there was no interference with the anodized region, so that a glossy high-quality black oxide film was obtained. On the other hand, in the comparative example product (Comparative Example 1), when the anodic oxidation time was close to 20 hours, color unevenness in which a gray portion was mixed with the black background began to occur. Therefore, when the voltage was checked, it was slightly lowered, so the voltage was gradually increased and the situation was observed. When the color unevenness disappeared, the voltage was set. This operation was repeated several times each time color unevenness occurred, but after 40 hours passed, color unevenness frequently appeared, and even if the voltage was adjusted variously, the color unevenness did not disappear and the operation continued. I stopped. When the cause was investigated, copper was thickly deposited on the inner surface of the cathode ring for anodization, which was considered to be because the electrolytic conditions were slightly deviated. During this period, the yield of forming a high-quality black oxide film with no color unevenness was 73%. The case where the black oxide film is formed on the copper wire has been described above, but it goes without saying that the same effect can be obtained when the method of the present invention is applied to a copper-coated composite wire such as a copper-stabilized superconducting wire.

[0012]

As described above, according to the method of the present invention, a high-quality black oxide film can be continuously and efficiently formed on a copper wire for a long period of time, which is a significant industrial effect.

[Brief description of drawings]

FIG. 1 is an explanatory view of essential parts showing an example of an embodiment of an anodizing device used in a method of the present invention.

FIG. 2 is an explanatory view of a main part of an anodizing device used in a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrolyte 2 Electrolyzer 3 Cathode for anodic oxidation 4 Copper wire 5 Anode for copper ion removal 6 Cathode for copper ion removal 7 Storage tank

Claims (1)

[Claims] 1. A method for continuously forming a black oxide film on a copper wire by an anodizing method in an electrolytic solution, wherein a copper ion-removing electrode is arranged in the electrolytic solution to elute copper from the copper wire. A method for forming a black oxide film on a copper wire, which comprises depositing and removing ions on the electrode.