JPS61127894A - High-current density electrolytic cell for metallic strip - Google Patents

Abstract

PURPOSE:To remove efficiently the gas generated during plating from an electrolyzing surface and to execute high-speed electrolytic treatment at high current density by embedding a suitable number of members formed with apertures into insoluble electrodes of an electrolytic cell and discharging the gas through the apertures. CONSTITUTION:A suitable number of the members (protective bodies) 3 formed with the apertures equal approximately to the width of a strip 1 are disposed at suitable intervals into the insoluble electrodes 2. The gas generated during plating is discharged through the apertures of such protective bodies 3 from a plating chamber. The higher effect is obtd. by forming the 2nd apertures on the outside of the apertures on both sides of the bodies 3 in the transverse direction of the strip to form the circulation path to suck the plating liquid including the gas through the 1st apertures and returning the same through the 2nd apertures to the plating chamber. The treatment of the metallic strip with the high current density is made possible by the electrolytic cell having the above-mentioned mechanism.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention efficiently removes oxygen gas, hydrogen gas, etc. generated during electrolysis from the electrolytic surface in the electrolytic treatment of metal strings using an insoluble electrode. This invention relates to an electrolytic cell that enables high-speed electrolytic processing using current density.

<Conventional technology and its problems> In general, in the electrolysis of metal strips, insoluble electrodes are often used, which do not require electrode replacement, can maintain a constant electrode surface shape, and can perform uniform electrolytic treatment. .

When performing high-speed plating with high current density while flowing a liquid between the insoluble electrode and the metal strip,
There are the following problems.

(1) By electrolysis, 10
At 0% current efficiency, oxygen gas is generated and accumulates between the electrode and the metal strip.

(2) As the current density increases, the amount of gas generated increases proportionally.

(3) On the other hand, high current density increases the voltage between the electrodes, which increases power costs. For this reason, when the gap between the electrodes is narrowed, the amount of gas generated does not change, so the narrower the gap between the electrodes, the higher the gas occupancy factor, and the more difficult it is for gas to escape, impeding the plating process.

The following are examples of conventional techniques related to such gas discharge between electrodes.

(1) Japanese Patent Publication No. 53-18167 "Through a large number of small holes or slit holes from the electrode surface facing the strip (having a chamber storing the processing liquid at the back),
Spray the treatment liquid in a jet onto the conductive strip.
A method of exhausting gases generated during electrolysis. ” and the force distribution method has the following problems.

■ The liquid ejected from the many small holes collides with each other. Since the liquid in the areas where they collide stays locally between the poles, the gas present there is not easily discharged. Therefore, high current density plating cannot be achieved.

■ The liquid between the electrodes flows outward from the periphery of the anode, so the flow velocity distribution is not uniform in the width direction of the strip. In particular, it is assumed that the flow velocity between the central part of the strip and the other parts is different, and depending on the type of alloy plating, the uniformity of the plated sliding alloy components may be reduced, which is disadvantageous. In addition, since the maximum allowable current density locally depends on the part where the liquid flow rate is slowest, high current density plating cannot be achieved. A metal strip electroplating cell characterized by being provided with an electrolytic solution spout that allows the electrolytic solution to flow out from the edge to both edges.'' This technology was also described in the above-mentioned Japanese Patent Publication No. 53-18167.
Regarding the issue, there are the same problems as pointed out in ■.

Therefore, in a high current density electrolytic cell, a means for effectively removing a large amount of gas generated from the surface of an insoluble electrode has not yet been realized.

<Objective of the Invention> The object of the present invention is to solve the above-mentioned problems and increase the input current in a metal strip high current density electrolytic cell. The side seal is used to make the flow velocity distribution of the plating solution uniform, and the running direction of the metal strip and the direction of the plating solution flow are opposite to each other.
■Even when the distance between the electrodes is narrowed, a large amount of gas generated from the insoluble electrode surface can be effectively removed.
In addition, the opening prevents the risk of contact between the metal strip and the electrode, lowers the gas space factor between the electrodes, and allows the electrolyte flow rate to be almost uniform at any location in the electrolytic cell. The present invention aims to provide a high current density electrolytic cell of a metal strip in which a member formed with a metal strip is embedded in an insoluble electrode.

<Specific Structure of the Invention> J: The first invention that achieves the above-mentioned object is a high current density electrolytic cell in which a metal strip is plated using an insoluble electrode in a plating solution flowing in a plating chamber. A metal strip characterized in that a member having an opening extending over a length corresponding to the width of the strip is embedded in the insoluble electrode, and gas generated during plating is discharged from the plating chamber through the opening. It is a high current density electrolytic cell.

Further, the second invention provides a high current density electrolytic cell for plating a metal strip using an insoluble electrode in a plating solution flowing in a plating chamber, in which a first electrode is formed over a length approximately corresponding to the width of the strip. A member having an opening and a second opening formed outside the first opening is embedded in the insoluble electrode.

A high current density electrolytic cell for a metal strip, characterized in that a circulation path is formed for sucking a plating solution containing gas generated during plating from the plating chamber through the opening and returning it to the plating chamber through the second opening. be.

The present invention will be explained in detail below using preferred embodiments of the present invention.

The first invention is to allow gas generated during plating to escape naturally from the protective body having an opening, whereas the second invention is to allow gas and plating solution to escape from the opening in the protective body. It performs forced circulation by sucking in and returning the water. The protector will be explained in detail below.

FIG. 1 shows a cross-sectional view of a horizontal electrolytic cell of a metal strip having an opening-formed member (hereinafter referred to as a protector) 3 according to the present invention, and FIG. 2 is a side cross-sectional view of the plane shown in FIG. Show the diagram.

The protector 3 has a width as narrow as possible in the longitudinal direction of the strip, and a member having an opening approximately the length of the strip width is inserted into the insoluble electrode (anode) at appropriate intervals in the longitudinal direction of the electrode. Bury the quantity. Although it is desirable that the strip has a width as narrow as possible in the longitudinal direction, a minimum width is required to form an opening, and a width of 25 mm or less is preferable. Although the length varies depending on the width of the strip, it is desirable that the length be approximately the width of the strip and span the entire width of the insoluble electrode.

The protector 3 is buried so as to slightly protrude from the surface of the electrode 2.

If it protrudes too much, it will disturb the plating solution flow.

It is preferable to set it to 20% or less of the distance between poles.

This protector 3 forms a first opening 10 over a length approximately corresponding to the strip width, and discharges gas generated during plating from the plating chamber through the first opening 10 along with the plating solution.

Furthermore, on both sides of the protector 3 in the strip width direction,
It is preferable to form the second opening 11 outside the first opening 10. By forming the first and second openings in this manner, a circulation path 13 is formed in which the plating solution containing gas generated during plating is sucked through the first opening 10 and returned to the plating chamber through the second opening 111. The circulation path 13 includes a pump 7 for suctioning the plating solution and a flow rate adjustment valve 8 for adjusting the flow rate.
It is good to have a

When a portion of the plating solution is carried out from between the electrodes through the first opening 10, the flow rate of the plating solution decreases toward the plating solution outlet side 12, so the flow velocity decreases, and the flow velocity distribution in the longitudinal direction of the strip becomes uneven. . To solve this,
The plating solution carried out from the first opening 10 is returned to the plating chamber from the second opening 11.The strip does not pass through both sides of the electrode width, and the gap between the electrodes is widened by the thickness of the strip.
At the same liquid flow rate, the flow velocity is slower than the center part between the electrodes, so the second opening 11 allows the plating solution to be discharged, thereby making the flow velocity distribution uniform in the width direction of the strip.

Furthermore, if the side seals 6 form a closed circuit between the electrodes, the flow velocity distribution in the width direction and length direction of the strip becomes even more uniform.

The first opening and the second opening may be composed of one or more openings, and the electrolytic solution sucked from the first opening 10 corresponding to the electrolytic surface (the maximum middle of the strip) is transferred to the protector 3 through the second opening 11. It is discharged from both sides and returned to the plating chamber 12. In this case, it is desirable that the suction and discharge cross-sectional areas be approximately the same. In addition, the shape of the opening can be any shape such as a square such as a slit, a round shape, a polygon, an ellipse, etc., and the cross-sectional area of suction and discharge can be made almost the same by changing the diameter, number, or density of holes. You can also use it as It is desirable that the amount of liquid sucked out from the slit corresponding to the electrolytic surface be within 20% of the interelectrode flow rate; if it exceeds 20%, the flow rate within the interelectrode will fluctuate, and the space and equipment for suction and discharge will also become larger, making it impractical. Not.

Note that the gas generated from the electrode surface has a characteristic of flowing directly along the electrode surface, so there is no need to unnecessarily increase the amount of liquid sucked out.If the minimum necessary flow rate is determined by experiment, the gas generated can be easily removed. It is possible to efficiently remove it from the opening.

What is the interval between protectors installed in the longitudinal direction of the electrode surface?

The effective length of the electrode is preferably every 250 to 750 mm. 250mm
Even if it becomes shorter, the gas removal efficiency of the electrolytic surface does not improve any further. On the other hand, if it exceeds 750 mm, gas between the electrodes cannot be removed sufficiently.

It is desirable that the material used for the protector be insulating, but
A metal that forms a strong, highly insulating passive film on the surface, such as Ti, can also be used. Typical examples thereof include Teflon, polypropylene, and FRP.

The protector 3 having the above structure can be applied to the electrode of any type of electrolytic cell such as a horizontal electrolytic cell, a vertical electrolytic cell, a radial electrolytic cell, etc.

An example of the structure of the protector 3 is shown in FIG.

The protector 3 has a protrusion 15 whose front surface 16 guides the gas-containing plating solution toward the opening 17 . Opening 17
may have the same width throughout, but especially in cases where plating solution is circulated, the center portion 18 may be narrower, with one width at both ends 1.
9 is preferably configured to be wide. In this case, opening 1
8 and 19 is preferably separated by a partition wall 20.

EXAMPLE A steel plate strip was plated using the horizontal cell of the present invention shown in FIGS. 1 and 2. A protective body made of Teflon is placed on the PB-based insoluble anode for 500 m in the longitudinal direction of the electrode.
Two electrodes were buried in one anode at an interval of m, and the plating solution was sucked and circulated at a rate of about 300 m/lin. Distance between electrode and strip #5~15■, line speed maximum 300 m/
win, plating solution ejection speed maximum 300 m/win
When plating was carried out using countercurrent flow, almost no gas bubbles were observed near the insoluble anode, and plating was successfully carried out at a high current density of 300 A/d2 at the maximum current density.

Furthermore, as mentioned in 1, even when the gas is naturally released from the protector without suctioning and forcibly circulating the plating solution, the gas occupancy factor near the insoluble anode is significantly reduced. , relatively good plating could be performed.

<Effects of the Invention> Since the high current density electrolytic cell of the metal strip of the present invention has an insoluble electrode in which a member (protector) with an opening is embedded, a large amount of gas generated from the surface of the insoluble electrode during plating can be effectively used. Furthermore, there is no risk of contact between the metal strip and the electrode, even when the distance between the metal strip and the electrode is narrowed to achieve high current densities.

Further, the present invention has a second opening formed outside the first opening, and the plating solution containing the gas sucked from the first opening is transferred to the second opening.
Since it also has an insoluble electrode embedded with a member that forms a circulation path that returns from the opening to the plating chamber, it is possible to forcibly and effectively remove a large amount of gas generated from the electrode during plating.
Furthermore, the flow velocity distribution of the plating solution in the plating chamber can be made uniform.

Therefore, in order to perform high-speed, high-efficiency plating, the present invention can also be used in the following electrolytic cell to provide a high current density, without gas remaining on the electrode surface.
High-speed electrolysis is possible due to high current density.

■When the insoluble electrode is lengthened to achieve high current density without increasing the number of electrolytic cells.

■When a side seal is used between the electrodes to make the flow velocity distribution of the plating solution uniform.

■When the running direction of the strip and the flow of the plating solution are made to flow in opposite directions to increase the relative speed of the plating solution.

■When the distance between electrodes is narrowed.

Furthermore, the present invention has more significant effects when applied to alloy plating that generates a large amount of gas.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of the present invention in a horizontal cell, and FIG. 2 is a side sectional view taken along the IT--IT line in FIG. 1. FIG. 3 is a schematic sectional view showing an example of the present invention in a radial type cell, and FIG. 4 is a side sectional view taken along line 1'V-IV in FIG. 3. FIG. 5 is a perspective view of the protector. Explanation of symbols■...Metal strip, 2...Insoluble electrode, 3...
・Protective body (with slit), 4... Ladder to nozzle, 5
...Conductor roll, 6...Side seal, 7
... pump, 8 ... flow rate adjustment valve, 9 ... main roll, 10 ... 13th f1 port, 11 ... second opening, 12 ... plating chamber, 13 ... circulation path, 14...
・Plating solution outlet side, 15...Protruding part, 16...Front surface, 17...Opening part, 18...Narrow width part, 19...Wide part, 20...Partition wall FIG, I FIG ,2 FIG,3 FIG,4

Claims (2)

[Claims] (1) In a high current density electrolytic cell in which a metal strip is plated using an insoluble electrode in a plating solution flowing in a plating chamber, a member with an opening extending over a length approximately equivalent to the width of the strip is attached to the insoluble electrode. 1. A high current density electrolytic cell of a metal strip, characterized in that the metal strip is buried and gas generated during plating is discharged from the plating chamber through the opening. (2) In a high current density electrolytic cell that uses an insoluble electrode to plate a metal strip in a plating solution flowing in a plating chamber, a first opening formed over a length approximately equivalent to the width of the strip; A member having a second opening formed on the outside is buried in the insoluble electrode, and a plating solution containing gas generated during plating is sucked from the plating chamber through the opening, and into the plating chamber through the second opening. A metal strip high current density electrolytic cell characterized by forming a return circulation path.