JPH10317197A - Electric nickel for plating, cathode plate for manufacturing the same, and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized electric nickel for plating having a small surface unevenness and a small variation in sulfur distribution, a method for economically producing such electric nickel, and a cathode plate used in the method. I do. SOLUTION: A cathode plate whose surface is covered with a non-conductive film 2 except for a plurality of hemispherical conductive portions 4 is used. Is peeled off. The obtained electric nickel 5 has a substantially hemispherical dome shape having a substantially uniform thickness and a void inside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to small electric nickel used as an anode for nickel plating and a method for producing the same.

[0002]

2. Description of the Related Art Electric nickel, which is used as an anode material for nickel plating, is usually in the form of a small lump having a diameter of about several tens of mm, and is used in an anode holder such as a titanium basket of a nickel plating tank.

[0003] At this time, if a chip product obtained by cutting a plate-shaped electric nickel is used, it is difficult to handle at the time of loading into a titanium basket due to a sharp corner portion, and the corner portion remains in the mesh of the basket even after being loaded into the basket. This causes a so-called hanging on the shelf, which changes the state of filling in the titanium basket and causes uneven plating.

[0004] In view of this, it has been practiced to produce electrolytic nickel for plating in the form of small blocks with rounded corners by electrolysis. That is, the cathode plate is masked with a non-conductive film while leaving a plurality of usually circular conductive portions, and a small-sized electric nickel of a moderate size is electrodeposited on each conductive portion, and then the nickel is removed from the cathode plate. By peeling off, small rounded nickel with sharp corners is produced.

When sulfur (S) is dispersed in electric nickel for plating in an amount of about 0.0 n% (n is an integer of one digit), the polarity becomes weak and the nickel is easily dissolved.
For this reason, when electrodepositing electric nickel on the cathode plate as described above, an S source such as sodium thiosulfate is added to the plating solution by a method described in, for example, JP-A-6-322575. It is common practice to disperse and contain S in the resulting electric nickel.

[0006]

As described above, in order to obtain small-sized electric nickel for plating which is unlikely to be suspended in a titanium basket in a titanium basket, a cathode plate whose surface is masked with a non-conductive film except for a plurality of conductive portions. 2. Description of the Related Art It has been conventionally performed to produce electroplating nickel in the form of small blocks with sharp corners by electrodeposition using a nickel.

However, as shown in FIG. 1, when the cathode plate 1 masked with the non-conductive film 2 is used, the current that would have flowed through the masked non-conductive portion is applied to the non-masked conductive portion. Since the current is concentrated on 1a, the current density is higher than in the case of manufacturing a plate-shaped electric nickel, and the current is more concentrated on the peripheral portion than the central portion in the same conductive portion 1a.

For this reason, as shown in FIG. 1, the small-sized electric nickel 3 electrodeposited on the conductive portion 1a of the cathode plate 1 has a lump peripheral portion 3b bulging up and a lump peripheral portion 3b in comparison with the lump central portion 3a. Also, irregularities are formed. In the case of the electric nickel 3 having the swelling and irregularities formed on the surface as described above, the irregularities on the surface are suspended on the shelf when the electric nickel 3 is put into the titanium basket for plating. Was the cause.

Further, it is preferable that the sulfur to be added to improve the solubility of the electric nickel is uniformly distributed in the electric nickel. The diffusion of the S source in the liquid becomes insufficient. That is, the lump central portion 3a and the lump peripheral portion 3b in FIG.
Where the diffusion of the S source into the valley portion 3d formed on the boundary portion 3c and the lump peripheral portion 3b is insufficient, and the S grade is extremely insufficient inside the electric nickel 3 along this portion. Was the result.

As described above, when the S grade of the electric nickel varies, when it is melted as an anode for plating,
A portion having a low S grade causes poor dissolution, and unmelted portion is left. The unmelted residue accumulates in the titanium basket, so that the maintenance frequency of the titanium basket is increased, and further, it floats in the plating bath to cause poor plating.

The present invention has been made in view of such a conventional situation,
To provide small-sized electric nickel for plating with little unevenness of the surface that causes shelving in a titanium basket and small variation in distribution of sulfur, and to produce such electric nickel economically with good yield. It is an object of the present invention to provide a method and a cathode plate used in the method.

[0012]

Means for Solving the Problems In order to achieve the above object, electric nickel for plating provided by the present invention is small-sized electric nickel for plating used as an anode for nickel plating, and has a substantially hollow inside. It has a hemispherical dome shape.

The cathode plate used for manufacturing the electric nickel for plating according to the present invention has a surface covered with a non-conductive film except for a plurality of conductive portions, and the conductive portions project from the surface. Preferably, it has a substantially hemispherical convex portion.

The electric nickel for plating according to the present invention uses a cathode plate in which a plurality of conductive portions are formed of the above-mentioned convex portions, and deposits electric nickel on each conductive portion, and peels off the obtained electric nickel from the cathode plate. It can be manufactured by the following.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, in a conventional cathode plate covered with a non-conductive film while leaving a plurality of conductive portions, current concentrates on each conductive portion. Therefore, in the present invention, the surface area of the conductive portion is increased by changing the shape of each conductive portion provided on the cathode plate covered with the non-conductive film from a conventional planar shape to a convex shape, for example, a hemisphere, thereby increasing the surface area of the current. Relieve concentration. In the case of the conductive portion having a convex shape, the current is easily concentrated on the tip portion thereof, so that there is an effect of dispersing the current concentrated on the peripheral portion of the conductive portion.

For this reason, the concentration of current on the conductive portion of the cathode plate is reduced, and a round shape having a substantially uniform thickness with almost no unevenness on the surface and having a void inside is formed along the convex conductive portion. A dome-shaped electric nickel for plating can be manufactured. In addition, since there is no current concentration and uniform electrodeposition is performed, variation in S distribution is reduced, and it is possible to obtain electric nickel having uniform S quality and easy dissolution.

The shape of the projection provided on the conductive portion is preferably substantially hemispherical because it can be easily formed and the electrodeposited nickel is easily peeled off. Examples of the method of forming the convex portion include a method of forming the convex portion by cutting the cathode plate and a method of welding the convex portion to the cathode plate.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a SUS cathode plate having a length of 100.times.250 mm, as shown in FIG.
1a was masked with a non-conductive film 2 provided regularly at a pitch of 21 mm to obtain a cathode plate of a comparative example similar to the conventional one.
The number of conductive portions 1a provided on the cathode plate was 36.

On the other hand, a cathode plate 1 of the present invention having the same material (SUS) and dimensions but having a hemispherical conductive portion 4 as shown in FIG. 2 was prepared. That is, a plurality of hemispherical conductive portions 4 each having a diameter of 12 mm are regularly formed on the surface of the cathode plate 1 by grinding in advance at a pitch of 21 mm so that each hemispherical conductive portion 4 is exposed to the opening of the non-conductive film 2. The non-conductive film 2 was masked. The number of the hemispherical conductive portions 4 was 36, which is the same as that of the planar conductive portion 1a.

Using each of the above cathode plates, S-containing electric nickel was manufactured under the same electrodeposition conditions. That is, a nickel chloride solution was used as a plating solution, and an S source in the plating solution was used by dissolving sodium thiosulfate at a concentration of 0.013 g / l. Anode length 100 x width 250 x thickness 10 mm
The electric current was 3.8 A, and the current density at this time was 933 A / m ² in projected area.

FIG. 4 is a graph showing the relationship between the voltage and the conduction time at this time. In the case of the cathode plate of the present invention having a hemispherical conductive portion, the voltage is low and stable, but when a cathode plate made of a normal planar conductive portion is used, the initial voltage is extremely high, The voltage tends to decrease as electrodeposition proceeds.

When the obtained electric nickel is a normal flat cathode plate, as shown in FIG. 1, the current concentrates on the periphery of the conductive portion 1a. The unevenness of the surface was severe, for example, the lump peripheral portion 3b protruded higher than the lump 3a, and the lump peripheral portion 3b was also formed with irregularities. Moreover, when the cross section of the electric nickel 3 is observed with a microscope, the dispersion of S is non-uniform, and
In the inside along the valley portion 3d of the unevenness formed in the boundary portion 3c of the lump peripheral portion 3b and the lump peripheral portion 3b, a portion lacking S was observed as a white band.

On the other hand, when the cathode plate of the present invention having a hemispherical conductive portion is used, as shown in FIGS.
And has a hemispherical dome shape having a cavity corresponding to the hemispherical conductive portion 4 inside, and has a substantially uniform overall thickness, almost no irregularities on the surface, and no current concentration. You can see that. In addition, since no current was concentrated, there was little variation in the S distribution, and almost no white band indicating S deficiency was observed by cross-sectional observation.

[0024]

According to the present invention, the surface area of the conductive portion is increased and the concentration of current in the peripheral portion is reduced by using the cathode plate in which the conductive portion is formed as a hemispherical convex portion. Therefore, it is possible to obtain a substantially hemispherical dome-shaped plating nickel having a uniform distribution of S, a substantially uniform thickness, and a void therein.

The substantially hemispherical dome-shaped electric nickel for plating has no sharp corners, so that it can be easily handled by hand, and the danger of hanging the shelf in the titanium basket is reduced. In addition, since there is a void inside, the filling rate becomes appropriately low when the titanium basket is filled, and the charging cost at the time of initial energization can be reduced.

Further, by using the cathode plate of the present invention in which the conductive portion is formed as a convex portion, it becomes possible to manufacture electric nickel at a lower voltage than in the prior art. In addition, since the distance between adjacent conductive portions is sufficiently maintained to prevent connection, the yield is expected to be improved, and even if the masking of the non-conductive film is deteriorated, the connection of the conductive portions is unlikely to occur. The service life of the plate can be extended. As a result, the cost of electric nickel for plating can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing electric nickel electrodeposited on a conventional cathode plate.

FIG. 2 is a schematic sectional view showing a specific example of a cathode plate provided with a hemispherical conductive portion according to the present invention.

FIG. 3 is a schematic sectional view showing a hemispherical dome-shaped electric nickel for plating of the present invention.

FIG. 4 is a graph showing a change in voltage due to a difference in shape of a conductive portion provided on a cathode plate.

[Description of Signs] 1 Cathode plate 1a Conductive part 2 Non-conductive film 3 Electric nickel 3a Lump central part 3b Lump peripheral part 3c Boundary part between lump central part and lump peripheral part 3d Irregular valley formed in lump peripheral part 4 Hemispherical conductive part 5 Electric nickel of the present invention

Claims (4)

[Claims] 1. A small-sized electric nickel for plating used as an anode for nickel plating, wherein the electric nickel has a substantially hemispherical dome shape having a void therein. 2. A cathode plate for producing nickel for plating, characterized in that the surface is covered with a non-conductive film except for a plurality of conductive portions, and the conductive portions have projections protruding from the surface. 3. The cathode plate according to claim 2, wherein the convex portion is substantially hemispherical. 4. A method for producing electric nickel for plating, comprising: depositing electric nickel on each conductive portion of the cathode plate according to claim 2; and peeling the obtained electric nickel from the cathode plate. .