JPS6215638B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for continuously electrodepositing metal layers on one or both sides of a strip of metal that is moved while being maintained in a non-horizontal direction. The electrolyte flows between strip metals constituting at least one plate-shaped anode and cathode.

Such methods can be used to deposit metals such as zinc, tin, brass, etc. on one side of strip metal. This method also allows a coating to be applied to both sides of the strip metal in one pass, and such a coating can be developed to have different thicknesses.

BACKGROUND ART AND PROBLEMS The well-known methods used for this purpose usually involve immersing a strip metal in an electrolyte.
Electrolyte is contacted on both sides of the strip metal until this is protected by special precautions. Therefore, even when using specially designed anode arrays and masks, there are significant problems with depositing metal on only one side. It is not possible to prevent electrodeposition of metal in small border areas on the back side of the metal strip in a satisfactory manner, and the resulting deposition is undesirably thick near the edges. These drawbacks are completely unavoidable even if the strip is brought into contact with the periphery of a roller, the roller being immersed in electrolyte and the strip being moved past the anode to effect electrodeposition. It is something. This is because the stop often exhibits some undulations at its ends due to the stress gradient caused by the rolling of the strip, so that the electrolyte remains on the strip even when the strip is in good contact with rollers in other areas. Because of the throwing power of the electrolyte, electrodeposition occurs over a larger area behind the strip.

Object of the Invention The concept of the invention differs from conventional methods in that the strip and the anode are no longer immersed in the electrolyte, but the hydrodynamic contact between the electrolyte on the one hand and the strip and the anode on the other hand keeps the electrolyte flowing continuously. The present invention provides a method for continuously electrodepositing a metal layer on one or both sides of a strip of metal, which is maintained by applying a metal layer to the metal strip.

SUMMARY OF THE INVENTION In this invention, a metal layer is continuously electrodeposited on one or both sides of a strip metal that is moved while being maintained in a non-horizontal direction. The electrolyte flows between strip metals constituting at least one plate-shaped anode and cathode. The electrolyte flows freely from the container in the upper region of the anode into the space between the anode and the strip metal and flows downward under its gravity as a cohesive fluid mass.

Example Examples of the present invention will be described below.

According to the invention, the electrolyte flows freely into the upper region of the anode and flows downward under the action of gravity to form a solid mass of fluid in the space between the anode and the strip metal, and the electrolyte flows into the space. Continuously supplied. This action causes the electrolyte to flow downward in an almost free fall, so that the surface of the electrode is heavily bombarded with solution.

According to another feature of the invention, the metal strip is bent at an angle such that a cohesive mass of fluid constituting the electrolyte flowing downwardly is maintained in the space between the anode and the metal strip; The distance between them is 2 to 20 mm, preferably 10 mm. For example, if the current density is high, the distance between the strip metal and the anode should be slightly smaller at the end away from the current supply terminal, in order to compensate for the small voltage drop along the anode (in the direction from the terminal). This is desirable.

Angle between strip metal and vertical line max. 30
I found out that ゜ is fine.

In connection with the method for supplying electrolyte to the space between the anode and the strip metal, a preferred embodiment of the method according to the invention provides that at least a portion of the electrolyte supplied to the space between the anode and the strip metal is supplied to the anode. At the top, the above-mentioned space may be entered, for example by crossing an overflow weir or by a vessel having a slot or similar means, so that the electrolyte flows from there into a collection vessel up to the anode.

In other embodiments of the invention, at least a portion of the additional electrolyte supplied to the space between the anode and the strip metal is provided through a plurality of holes or slots extending through the anode. Enter the space. It will also be understood that the two last mentioned embodiments may be combined.

The use of very high current densities when depositing fast moving strips in HD plants creates certain complications. For mechanical and electrochemical reasons, and to dissipate the heat generated by the Joule effect, the rate at which the electrolyte is supplied and the distance between the strip metal and the anode must be relatively increased. It won't happen. As a result, the adhesion of the electrolyte to the metal surface and the influence of the viscosity of the electrolyte are reduced, and the electrolyte falls freely.

This not only sharply increases the rate at which the electrolyte flows through the cell, but also increases the difference in electrolyte flow rate in the upper and lower parts of the cell, resulting in a The cross-sectional area will vary along the anode.

This problem is solved by the present invention, in which the distance between the anode and the strip metal remains constant or decreases in the direction of electrolyte flow.

In the present invention, it has been found that it is preferable to provide a distance between the strip metal and the anode that continuously decreases in the direction of flow.

If the distance between the strip metal and the anode decreases downward, the desired configuration from hydrodynamic concepts is obtained by the equation d=k√. Yes,
Here, d is the distance, s is the downflow path length of the electrolytic solution, and k is a constant.

A further improvement provided by the present invention is that the distance between the anode and the top edge of the strip metal and the distance between the anode and the bottom edge of the strip metal are adjusted independently of each other.

Another requirement is that the capacity of the plant can be increased even if the floor space is very small, and that this can be achieved without spending too much money.

The anode may increase in length in the direction in which the strip is moved. However, the extent to which it can be increased is limited for various reasons as described below. That is, the anode has a limited current carrying capacity, the terminals that supply current to one point on the anode are very bulky and large, and have a complex configuration to dissipate heat, and the heavy anode They present structural problems due to their heavy weight, etc., and very long anodes present additional hydrodynamic problems. On the other hand, the strip may be moved up and down within a length of 10 to 20 meters or more. Arrange at least two anodes near the strip metal, one on top of the other, and control the flow of electrolyte to the top anode based on each anode, and then freely flow to the next lower anode. Thus, it has been found that a simple and desired configuration can be obtained by the present invention.

In the embodiments described above, the electrolyte may be provided on both sides of the strip metal in a known manner for one-sided or double-sided deposition.

It has been found that for configurations with electrodes on both sides of the strip metal, it is most preferable to select the polarity, voltage and current independently. This allows the strip to be coated with different thicknesses on both sides and to connect the cathode electrode to one side of the strip. This allows the strips on the non-metalized side to be cleaned or roughened. Such an action has been found to be desirable for further processing of the strip, such as painting, soldering, etc. Finally, the strip may be anodized, for example on one side, and coated with metal on the other side by cathodic electrodeposition.

In another embodiment, electrodes are provided on both sides of the metal strip, voltage is applied to only one of the electrodes forming the anode, and electrolyte is applied only to the space between the anode and the strip.

In yet another embodiment, the strip metal is coated on one or both sides, and the strip metal is moved adjacent to the continuous anode in alternating directions relative to the flow direction of the electrolyte, so that the strip metal It is moved alternately in the same direction and in the opposite direction relative to the electrolyte. This causes rapid movement of the solution over the surface of the strip, promoting electrodeposition.

In other embodiments, the strip metal is wetted with an electrolyte, preferably sprayed with or otherwise wetted with an electrolyte, to enhance core growth without the application of electrical current.

In a special embodiment of the invention, a zinc-nickel alloy is deposited on a strip metal, the direction of movement of the steel is changed once or several times with respect to the direction of flow of the electrolyte, and the electrodeposition is between 20 and 150 A/min. dm ² , preferably at a current density of 40 to 100 A/dm ² , the electrolysis consists of a suitable solution at a temperature of 40 to 70°C, preferably 45 to 60°C, and in this solution at least 80 g of each solubility in NiSO ₄ .7H ₂ O, at least
_Contains 150g/ _ZnSO4.7H2O and _2g / _H3BO3 .

In this method, a nickel-zinc ratio of 4:10 and 10:10, preferably 5:10 and 8:10, is maintained in the electrolyte, so that the electrodeposited layer is
It contains 15 wt.% nickel, preferably 9 to 13 wt.% nickel. In the present invention, when an insoluble anode is used, a method using a sulfuric acid electrolyte containing non-chloride ions that liberate chlorine may be used.
It is well known to electrodeposit alternating layers of zinc and nickel or layers with low and high nickel content using a sulfuric acid electrolyte so as to reduce the resistance of the coating to corrosion. For example, U.S. Pat. No. 4,313,802 discloses that a strip metal is laterally deposited in a pure sulfuric acid electrolyte containing zinc and nickel in a ratio between 10:15 and 10:40, limiting the current density to 5-40 A/ ^dm2 . A method of moving is disclosed.
High nickel conditions result in very high losses to the nickel being moved. Also, from 0.05
It has been proposed to add strontium sulfate as brightener in an amount of 10 g/ml, but this has various disadvantages, due to the very low solubility of strontium sulfate and its relatively high cost.

In the above-mentioned method according to the present invention, the PH value of the solution is maintained at 1 to 2, preferably 1.3 to 1.8, by adding sulfuric acid intermittently or continuously, and the pH value of the solution is maintained at 1 to 2, preferably 1.3 to 1.8. using the anode or electrode carbon in a well-known manner, metal oxide,
It has been found desirable to carry out the extraction of the metal during the dissolution of the metal hydroxide or metal carbonate, or while the metal or metal alloy itself is being chemically or anodically dissolved.

Sulfates, borates, boric acid (H ₃ BO ₃ ), aminosulfuric acid (NH ₂ SO ₃ H), formic acid (HCOOH), acetic acid (CH ₃ COOH), and glucose and their salts are added to sulfuric acid and mixed. You can also do this.

The apparatus used in this method consists essentially of at least two deflection rollers arranged one above the other in a manner known per se, and offset from the horizontal and substantially parallel to the strip metal. at least one insoluble anode, a terminal for supplying current to a cathode made of a strip metal wound around the anode and a roller, driving means for driving the strip, at least one container for controlling an electrolyte, and an electrolyte. and a pipeline that supplies electrolyte to the space between the anode and the strip metal.

In one example of this apparatus, the device for supplying electrolyte comprises an elongated container, which is provided on top of the anode and is continuously supplied with electrolyte, for example by a pump circulating the electrolyte. It is provided above the space between the anode and the strip metal, and has one or more slots, through which the electrolyte is continuously supplied from above into the space between the anode and the strip metal.

In other embodiments, the anode is formed with a plurality of through holes or slots, a container is provided, one wall of which is defined by an open anode wall, and a pipeline is provided from the pump. It is guided into the container and serves to continuously supply electrolyte to the container.

The devices in the two last mentioned embodiments may also be combined with each other. The means for supplying the electrolyte to the top of the anode may also include a single aperture formed in the anode near its top and a pipe connected to the back side of the anode for supplying the electrolyte.

Next, the method and apparatus according to the present invention will be explained with reference to the drawings.

In FIG. 1, a strip of metal 1 is continuously pulled in an inclined orientation around deflecting rollers 2 and 3 either upwardly or downwardly past an anode 5. In FIG. Further, the anode 5 is also inclined. A predetermined voltage or a predetermined current between the anode 5 and the strip metal 1 is maintained by currents from the current supply terminals 4 and 6. In order to apply an electric current and electrodeposit a metal layer on the side of the strip metal 1 facing the anode 5, the electrolyte is pumped up from the electrolyte collecting container 7 by the pump 8 and transferred to the container via a pipeline. 9 is continuously supplied. The container 9 has a vertical slot through which the electrolyte flows continuously into the space between the strip metal 1 and the anode 5. The electrolyte fills the space and flows downwards in the space and then into the collection vessel 7.

In FIG. 2, the strip metal 1 and the anode 5' have a vertical orientation, and the anode 5' consists of a box with a section 11 to which the electrolyte is supplied by a pump 8. The electrolyte rises uniformly to the top position of the box through a through slot 12 provided in the wall facing the strip metal 1.
and flows through the drain 13 into the space between the anode 5' and the strip metal 1 at different levels. The electrolytic solution is returned to the collecting container 7 from that space. FIG. 3 shows an anode 5', which is closed at the top and has a plurality of holes 14, which are arranged in the upper part of the anode 5' according to different hydrostatic pressures. Large and closely spaced and smaller and spaced apart below the anode 5'. A wide slot 15 provided above the hole 14 constitutes a drainage outlet.

Adjacent to this passage, a single strip is pulled through the plant along a passage in order to make the electrodeposition on the side of the strip as different as possible with different thicknesses and to design a plant of suitable capacity. It is desirable to provide a plurality of such electrolyte cells one next to the other or one above the other.

Some examples based on this concept are shown in Figure 4a.
4b and 5a to 5d, in FIG. 4 the strip and anode are arranged in a vertical orientation, and in FIG. 5 the strip and anode are arranged in an inclined orientation. This is the case. Fourth
The embodiment shown in Figure a uses a box-shaped anode. Also, in Figure 4b, one side and the same side of the strip is moved twice (upward and downward) by the same anode box, so that the box has holes or slots in the two mutually opposite walls. and an exhaust port, the effective anode surface area of the box described above can be doubled. According to FIG. 4c, a one-sided anode box may be provided on the other side of the strip, making it particularly suitable for depositing metal layers of very different thickness on the two sides of the strip. You can get a plant. The plant is the fourth
As shown in Figure d, separate anodes may be provided and enlarged so that the same anode surface area is available on each side of the strip. FIG. 4e shows anodes stacked one above the other. Furthermore, FIG. 4f shows the configuration of an anode box that is housed without any gaps, and most of both sides of the anode box are effectively utilized in the HD plant.

The use of slanted electrodes as shown in Figures 5a-5d allows the height of the plant to be reduced. Additionally, hydrostatic and hydrodynamic effects can be exploited in connection with the inclined position.

The configuration of FIGS. 5a and 5b is for electrodeposition on one side. Figures 5c and 5d
The configuration shown in 2 may be used when electrodeposition is performed on both sides.

Figure 6 shows strip metal 1, which is 2
It is wound around two upper deflection rollers 3 and one lower deflection roller 2. The upper deflection roller 3 is provided with a current supply terminal (not shown). Anodes 5 are provided on both sides of the strip metal 1, and each of them is connected to a carrier 5''. As shown by arrows A and B, the carrier 5'' extends from the strip metal 1 around a horizontal axis (arrow A). (arrow B). In this embodiment shown as an example, the carrier 5'' is connected to the anode 5, preferably at the center of the anode 5. From the dotted line indicating the anode 5, the distance from each anode 5 to the strip metal 1 and the distance of each anode 5 to the strip metal 1 are determined. It will be appreciated that the inclination can be adjusted as desired. In a preferred embodiment of the invention, the carrier 5'' is mounted in an electrically conductive and insulating manner and is provided with a current supply terminal (not shown).
It is equipped with The anode 5 and the deflection roller 2 are provided within the cell case 16. The electrolyte flowing from the anode 5 is controlled at the bottom of the cell and pumped 8
rises to the top or end of the anode 5 by
Complete the cycle. As can be seen from FIGS. 6 and 7, the strip metal is plated on only one side. For this purpose, the electrolyte is applied to the strip metal 1
and the outer anode 5 provided between the cell case 16 and the wall of the cell case 16.

In the embodiment shown in FIGS. 8 and 9, both sides of the strip metal 1 are plated. For this purpose, an electrolyte is supplied to all anodes 5.
As is clear from FIGS. 7 and 9, in the embodiment shown in FIGS. 8 and 9, the strip metal 1 is completely surrounded by the anode, and the electrolyte is injected into the inner anode 5. A laterally extending end is provided so that it cannot flow laterally.

In another embodiment of the invention (not shown),
Anodes are connected to the top and bottom ends of the carrier. These carriers can be adjusted individually to each other in relation to the distance between the strip metal 1 and the anode 5. At least one carrier is mounted in an electrically conductive and insulating manner and is provided with a current supply terminal.

Also according to the invention, the surface of each anode 5 facing the strip metal 1 is flat or convexly curved with respect to the direction of the strip metal. Its curvature can be determined by the formula d=k/√, where d is the distance between the strip metal 1 and the anode 5, s is the downflow path length of the electrolyte, and k is a constant.

In the embodiment of the invention shown in FIG. 10, two anodes 5 are provided, one above the other. It will be appreciated that more than one anode may be provided, one on top of the other. The electrolyte flows freely from the slot in the supply line 18 to the upper anode 5 and out thence to the collecting trough 19. When this collecting tub 19 is filled with electrolyte, the electrolyte overflows from the edge of the collecting tub 19 and flows out, and is continuously supplied to the lower anode 5 under the control of the redirecting tub 10.
Flow freely into this. The electrolytic solution flowing out from the lower anode 5 is transferred to a collecting container 7 provided with a drainage channel 22.
controlled by The electrolyte that has left the collection container 7 is pumped up to the supply line 18 by a pump (not shown). The remaining electrolyte adhered to the strip metal 1 is removed by the squeezing roller 23, and then flows out into the collecting container 7 again.

To improve the power distribution, a plurality of additional rollers 24 are provided for the current supply. These rollers 24
each is provided between two adjacent anodes 5.

In the embodiment shown in FIG.
The electrolyte taken out from the tank 1 changes direction.
0' to the collecting trough 19', the electrolyte then overflows the edge of the collecting trough 19' and flows into the space between the anode 5 and the strip metal 1 below.

The embodiment shown in FIG. 12 shows a configuration for controlling and changing the direction of the electrolyte. This configuration has a narrow collecting funnel 25 whose large opening 26 receives the electrolyte of the upper anode 5;
The electrolyte then flows from the small opening 27 through the pipe to the anode 5 below. As shown in FIG.
and a buttful woven fabric 29. These fabrics direct the electrolyte toward the small openings and slow the flow.

Modified collection funnel 2 shown in FIG.
5' is circular and has a guide fabric 28' and a funnel fabric 29'.

In the practical embodiment of the invention shown in FIGS. 15-17, the pump 8 is structurally integrated with the cell case 16. These parts are the same as those shown in FIG. 6, and therefore are designated by the same reference numerals. As in the example shown in FIG. 6, two upper deflection rollers 3 and one lower deflection roller 2 are provided. Anode 5
is provided again in the space between the upper deflection roller 3 and the lower deflection roller 2. The anode 5 on one or both sides of the strip metal 1 and the lower deflecting roller 2 are surrounded by a cell case 16 with an open top, at the bottom of which the electrolyte is controlled. The electrolyte is continuously pumped up to the anode 5 by a pump 8 through a lateral passage provided in the cell case 16 . The pump 8 is installed on the side of the cell case 10,
It is provided at the bottom level of the case. The side walls of the case 16 are double-walled, thereby defining a lateral passage 20. The bottom of the cell case 16 is connected to a station (not shown) via a line in order to dissolve the electrolyte.

Effects of the Invention The method according to the invention and the device for carrying out the method provide a number of benefits. Thus, for example, wetting of the strip metal can be prevented by simple deactivation of the electrolyte pump, even if the electrolyte has a high acidity.
Thereby, etching of the strip metal and other similar effects can be prevented even if the strip metal is stopped for a long time. Furthermore, the distance between the strip metal and the anode may be extremely small; in most cases,
It may be much smaller than 20 mm, which is said to be the limit. This is due to the rapid falling of the electrolyte under the action of gravity, which causes the electrolyte to flow rapidly at the boundary layer.
This is because the boundary layer is always thin and only a very low concentration of polarization is generated at the electrode. The heat generated in case of high current densities is rapidly dissipated and any gas that may be formed and reduced boils off and the wet electrode surface is immediately removed. For this purpose, the terminal voltage and power may be low, resulting in extremely low power losses due to overheating of the solution due to the Joule effect, and yet a very high maximum possible power density. This allows a particularly economical and compact design. The strip metal can exhibit the important advantage that it is wetted by the electrolyte only on its advancing side, so that even small electrodepositions on the rear side of the strip metal are prevented. The fluid mass filling the space between the electrodes is rapidly compressed and torn apart by dynamic action at the ends of the strip, so that in effect there is no appreciable increase in current density at the ends of the strip. It's not a big deal, and as a result, you won't need a mask. For this reason, if the anode is wide enough, it can easily be used even if the strips are curled, ie deflected laterally as they pass through the cell.

If it is necessary to dissolve the metal in an electrolyte and maintain the concentration of metal ions, this can be achieved by chemical or anodic dissolution cells, which are known per se.

[Brief explanation of the drawing]

1 and 2 are perspective views respectively showing two embodiments of the device applied to the present invention, FIG. 3 is a perspective view showing details of the device, and FIGS. 4a to 4f and 4f. 5a to 5d are side elevation views schematically showing different ways in which a plurality of electrolyte cells according to the invention can be arranged in one and the same stripping plant; FIG. 6; 7 is a cross-sectional view schematically showing an apparatus according to the present invention for plating one side of strip metal, FIG. 7 is a plan view showing the apparatus of FIG. 6, and FIG. 8 is for plating both sides of strip metal. 6 is a cross-sectional view showing the device used in FIG. 6, FIG. 9 is a plan view showing the device in FIG.
Figure 0 is a cross-sectional view of an apparatus according to the invention for coating both sides of a strip metal in an apparatus in which two anodes are arranged one above the other; Figures 11 and 12;
Figure 13 is a plan view showing two examples of means for collecting and directing the electrolyte;
The figure is a sectional view taken along the line - in Fig. 12, Fig. 14 is a sectional view similar to Fig. 13, but showing an example of means for changing different collections and directions, and Fig. 15 is a sectional view of this figure. A cross-sectional view showing still another embodiment of the device according to the invention, FIG. 16 is a cross-sectional view taken along the line - in FIG. 15, and FIG. 17 is a cross-sectional view taken along the line - in FIG. 15.
FIG. 1 is a strip metal, 2 and 3 are deflection rollers,
4 and 6 are current supply terminals, 5 is an anode, 7 is an electrolyte collecting container, 8 is a pump, 9 is a container, 12 is a slot, 13 is a drain port, 14 is a hole, and 15 is a wide slot.

Claims (1)

[Claims] 1. A method of continuously electrodepositing a metal layer on at least one side of a strip metal that is moved while being maintained in a non-horizontal direction, the method comprising at least one plate-shaped anode and cathode. An electrolytic solution is flowed between the strip metals, an electrode is loosely fitted adjacent to the top of the anode, and the electrolyte is lowered by gravity so that it forms a solid mass of fluid in the space between the anode and the strip metals. A method in which a metal layer is continuously electrodeposited on one or both sides of a strip metal by flowing in a lateral direction and continuously supplying an electrolyte into the space to keep the space filled with the electrolyte. 2 The angle between the strip metal and the vertical line is the highest
30°, and the distance between the anode and the strip metal is between 2 and 20 mm. A method of continuously electrodepositing a metal layer as claimed in claim 1 on one or both sides of the strip metal. 3. A method of continuously electrodepositing a metal layer as claimed in claim 1 on one or both sides of a strip metal without increasing the distance between the anode and the strip metal in the direction of flow of the electrolyte. 4 Claims in which the distance between the strip metal and the anode decreases in a downward direction according to the formula d=k/√ (d=distance between the strip metal and the anode, s is the downflow path length of the electrolyte, and k is a constant) A method of continuously electrodepositing a metal layer according to claim 3 on one or both sides of a strip metal. 5. A metal layer according to claim 1, wherein a plurality of electrodes are provided on both sides of the strip metal, and the voltages supplied to the electrodes and their polarities are individually selected. Or a method of continuous electrodeposition on both sides. 6 In order to electrodeposit the zinc-nickel alloy on the steel strip, the relationship between the direction of movement of the steel strip and the direction of flow of the electrolyte is at least 1.
The above electrodeposition is inverted for 20 to 20 minutes with the electrolyte.
The ^electrolyte was
of a suitable solution at ~70°C, and in said solution at least 80 g/g of the concentration up to their respective solubility.
NiSO ₄ .7H ₂ O, 150g/ZnSO ₄ .7H ₂ O and 2g/
A method of continuously electrodepositing a metal layer according to claim 1 containing H ₃ BO ₃ on one or both sides of a strip metal. 7. A nickel-zinc ratio between 4:10 and 10:10 is maintained in the electrolyte to deposit a layer containing 8 to 15 wt.% nickel. A method in which a metal layer is continuously electrodeposited on one or both sides of a strip of metal. 8. A method of continuously electrodepositing a metal layer as claimed in claim 1 on one or both sides of a strip metal, wherein a pH value of 1 to 2 is maintained by adding a small amount of sulfuric acid in the bath. 9. The metal layer according to claim 1, characterized in that at least a part of the additional electrolyte supplied to the space between the anode and the strip metal is inserted into the space through an opening extending through the anode. A method of electrodepositing continuously on one or both sides of strip metal. 10. Claims in which at least two stacked anodes are provided adjacent to the strip metal, the electrolyte entering the upper anode being controlled based on said anode and flowing freely into the next lower anode. A method of continuously electrodepositing a metal layer according to claim 1 on one or both sides of a strip metal. 11. The lower reflective roller and at least a portion of the electrode are located in a cell with an open top, from which a pump draws up the electrolyte and directs it to the anode through a passageway outside the cell case. A method of continuously electrodepositing a metal layer according to claim 1 on one or both sides of a strip metal.