JPH10317195A - Continuous electroplating method and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the current density of a continuously traveling base stock from being made nonuniform and to embody plating with the decreased compsn. variations in the thickness direction in plating films and excellent quality by installing perforated insulating materials between the opposed base stock constituting a cathode and anodes within a continuous electroplating cell and adjusting opening rates by changing the sizes of holes and the number of the holes per unit area. SOLUTION: The base stock 1 to be plated of a steel strip is made to travel continuously from the left side to the right side of Fig. and is supported by respective dam rolls 2 on the inlet and outlet sides of electrodes 4 which are the anodes. The distance between the electrodes is kept as constant as possible. Perforated plates 5 respectively consisting of the insulating materials are arranged parallel between the opposed electrodes 4 and the base stock 1 preferably in approximately intermediate positions with respect to the base stock 1 and the electrodes 4. The perforated plates 5 are formed of rectangular materials and are sufficiently sized to at least cover the electrodes 4. While the width thereof is similar to that of the electrodes 4, the length is slightly longer than that of the electrodes. In this example, the perforated plates are segmented to first to third zones in a longitudinal direction and their respective opening rates are changed to 30%, 40%, 50%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous electroplating method and an apparatus therefor, and more particularly to a continuous electroplating method and an apparatus therefor in which a current density distribution is made uniform along a traveling direction of a continuously running material.

[0002]

2. Description of the Related Art At present, high-speed plating with a high current density is carried out for the electroplating of hoop materials, that is, steel strips, wire rods, etc. in order to improve productivity. Plating on wires and strips is performed to obtain corrosion resistance and electrical properties.The performance of plated products depends on whether uniform plating weight is secured or alloy plating composition is stabilized. , And greatly varies depending on whether or not a plating film having a uniform physical property is realized.

[0003] The current density has a significant effect on the uniformity of the amount of deposition and the uniformity of the components deposited during alloy plating. And the current density, especially in the case of continuous plating, the distance between the poles,
It is greatly affected by the current density distribution of the anode and cathode.
In order to keep the distance between the poles constant, it is first necessary to accurately maintain the accuracy of the pass line of the steel strip or wire rod. It is necessary to ensure straightness.

[0004] Further, in order to make the current density in the anode electrode uniform, it is necessary to reduce the IR drop component generated in the anode. For this purpose, a material having high electric conductivity is used, or an insoluble electrode is used. In such cases, use a material with high electrical conductivity as the core material and line only the outer periphery with the electrode material, or in the case of a fusible electrode, increase the cross-sectional area in the direction of current flow in the electrode to increase the resistance value. In order to reduce the IR drop component from the structural surface of the electrode, for example, a method of reducing the number of components is adopted.

In order to prevent current concentration at the edge during plating electrolysis, a shield plate or the like is attached to prevent the concentration of power lines in the plating electrolytic cell. It is difficult to prevent the IR drop resulting from the specific resistance.
In addition, as the wire diameter becomes smaller, the generated IR becomes larger and a non-uniform current density distribution occurs in the cathode.

When an iron material is used as a plating material, the electrical resistance of an aqueous solution plating is relatively small from normal temperature to 60 ° C., but in molten salt plating performed at a high temperature, the electrical resistance increases and an IR drop occurs. The cathode current density distribution fluctuates greatly, and the effect on plating is large.

In continuous plating, power is supplied to the plating material from outside the plating tank by a metal energizing roll. The farther away from the feeding point at that time, the more difficult it is for electricity to flow due to the IR drop of the base material due to the relationship of the specific resistance of the base material and the distance. It is difficult to prevent the IR drop caused by the specific resistance of the steel strip or the wire itself, which is the plating base material. growing. In addition, in many cases, iron is plated as a plating base material, that is, a plating material, but in general, as the temperature of a metal material increases, the electric resistance tends to increase as the temperature increases.
Since the plating of the aqueous solution is carried out at a temperature from normal temperature to about 60 ° C., the electric resistance is relatively small and the influence is small. However, in the case of molten salt plating in which plating is performed at a high temperature, the electric resistance value also increases, and I
The R drop component is also large, so that the cathode current density changes greatly in the direction of travel of the plating material. As a countermeasure, in the continuous plating, the arrangement of the anode is inclined with respect to the pass line of the cathode, and a measure is taken to make the current density uniform by controlling the distance between the attached electrodes.

In the current high-speed electroplating, in order to prevent burning of the plating even at a high current density plating, a high-speed flow of a plating solution is performed to promote the supply of ions, thereby preventing burning of the plating. However, when the electrode arrangement is inclined, if the distance (cross-sectional area) between the electrodes is different, the flow speed of the plating solution differs depending on the part, and plating burning occurs at a place where the flow is slow,
Such measures are difficult to implement with high-speed plating.

[0009]

As described above, various proposals have been made in the prior art to make the distribution of the current density in the longitudinal direction uniform, but all of them have achieved sufficient effects. I couldn't say.

In the case of continuous electroplating, particularly continuous electroplating in which a strip-shaped or linear material is continuously passed in one direction to perform electroplating, an IR drop occurs due to the electrical resistance of the material, resulting in uneven current density in the traveling direction. Transformation occurs. When the current density becomes non-uniform, an abnormally high current density region is generated near a current-carrying point of the plating base material, and burning of the plating occurs.
In the case of alloy plating, since the composition ratio depends on the current density, the composition of the precipitate becomes non-uniform in the plating thickness direction.

Here, an object of the present invention is to develop a technique capable of realizing plating of excellent quality by preventing such nonuniform current density.

[0012]

Means for Solving the Problems Here, the present inventors have
Uniform cathode current density by adjusting the aperture ratio by installing a porous insulating material between the anode and cathode in the plating electrolyzer for continuous electroplating and changing the hole size and the number of holes per unit area In the case of using a soluble type pellet electrode system, the current distribution is adjusted by the electrode box itself by using an insulating porous plate having holes and adjusting the opening density in front of the pellet electrode box. .

[0013] Here, the present invention provides a method for performing electroplating on a material which is a continuously running cathode, by installing a perforated plate made of an insulator between a material constituting the opposed cathode and the anode. The continuous electroplating method is characterized in that the current density distribution is made uniform by adjusting the aperture ratio of the perforated plate along the direction of travel.

Another aspect of the present invention is an apparatus for electroplating a continuously running material, comprising: an anode and a perforated plate installed between the anode and a passage area of the continuously running material. A continuous electroplating apparatus comprising a perforated plate and an insulating material, the aperture ratio of which is adjusted in a material traveling direction.

As described above, according to the present invention, there is provided an electroplating method and apparatus in which a current density distribution is made uniform along a traveling direction of a plating material. In the continuous electroplating by the slag or the continuous electroplating by the molten salt, the current density distribution generated in the longitudinal direction of the material is adjusted by setting a perforated plate made of an insulator between the anode and the cathode and setting the aperture ratio of this perforated plate And a method and apparatus for making the current density distribution uniform.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The current density distribution at the time of plating in continuous electroplating is greatly affected by the number and positions of feeding points to the plating material and the size of the electrolytic cell (the length of the material in the electrolytic cell). That is, since the inherent electrical resistance of the plating material is a resistance component in the length direction, when a plating current flows, an IR drop occurs, and the closer to the power supply point, the more the electric current flows. Non-uniform density distribution occurs in the longitudinal direction of the plating material.

The IR drop itself has a large effect on the type of material, the cross-sectional shape (area) of the material, and the temperature during plating.
Ultra-thin plates, ultra-fine wires, etc. are susceptible to IR drop, and the effect of molten salt plating, which performs electroplating at a high temperature, is large when the plating material is metal, since generally the higher the temperature, the higher the electrical resistance value.

Here, according to the present invention, a perforated plate having holes formed in an insulator is placed in parallel between an anode and a material constituting a cathode. The size of the perforated plate depends on the shape of the plating material, but it is preferable that the perforated plate has an area large enough to shield the entire electrode surface.

By adjusting the size and the number of holes to reduce the degree of opening closer to the feeding point and increasing the opening ratio further away from the feeding point, the specific electrical resistance of the material to be plated can be canceled. Adjust the aperture ratio of the perforated plate. The aperture ratio affects the current density distribution.
Divided into 2 to 5 zones within the range of ~ 60%, each with approximately 10
It is provided with a difference of about%. Of course, it may be changed continuously.

The porous plate can be made of any material as long as it is an insulating material. For example, a rigid vinyl chloride plate, epoxy plate, acrylic plate, polyimide plate, etc. Resin material can be used. The shape of the hole may be any shape such as a circle, a triangle, or a square, but a round hole is preferable for processing and for adjusting the degree of opening.

FIG. 1 is a schematic explanatory view of a continuous electroplating apparatus according to the present invention, in which a steel strip material 1 to be plated continuously runs from the left hand side to the right hand side as viewed in the drawing.
Each of the anodes 4 is supported by a dam roll 2 on the entrance and exit sides of the electrode 4 to make the distance between the electrodes as constant as possible. A current from an external power source (not shown) flows from the electrode 4 as an anode, through the material 1, and in this case, toward the energizing roll 3, whereby metal is plated on the surface of the material 1 constituting the cathode. . Here, according to the present invention, a porous plate 5 made of an insulating material is disposed between each of the opposed electrodes 4 and the material 1, preferably at a substantially intermediate position with respect to the material 1 and the electrode 4. ing. The shape of the perforated plate 5 is a long rectangular material as shown in FIG. 1, and its size is large enough to cover at least the electrode 4. In the example shown, the width is similar to that of the electrodes, but the length is slightly longer both upstream and downstream. It may be provided in close contact with the electrode 4. In the illustrated example, the first to third zones are defined in the longitudinal direction, and the opening ratios of the respective zones are changed to 30%, 40%, and 50% from the side closer to the energizing roll forming the feeding point.

FIG. 2 is substantially the same as that of FIG. 1, but in the case of FIG. 2, the perforated plate 5 is first to fourth in the longitudinal direction.
Are divided into zones, each with an aperture ratio of 25%, 35
%, 45% and 55%. In FIG. 2, the same members as those in FIG. 1 are denoted by the same reference numerals.

FIG. 4 shows another modification, which shows an apparatus for continuously plating a plating material 1 with a vertical plating apparatus.
The plating material 1, for example, a SUS steel plate, is plated around the immersion roll immersed in the plating bath. In the illustrated example, the plating is performed only when the material 1 travels downward, but plating may be performed on both sides.

1 and 2 may be either an insoluble electrode or a soluble electrode. FIG. 4 shows a case where a soluble electrode pellet 6 is used and put in an electrode box 5 to be used as an electrode. The front surface of the electrode box 5, that is, the surface on the side facing the plating material 1 is made of a porous plate made of an insulating material.
As shown in the figure, it is divided into first and second zones in the vertical direction, and openings are provided with opening ratios of, for example, 35% and 45%, respectively.

FIG. 6 explains the definition of the aperture ratio in the perforated plate 5 of FIGS. 1, 2 and 4. In FIG. 6, when a circular opening is considered as the opening, its diameter d and its average taken in are considered. Assuming the lengths A and B of each side of the rectangle, the aperture ratio in the present invention is defined by the following equation.

[0026]

(Equation 1)

[0027]

Next, the operation and effect of the present invention will be described more specifically with reference to examples. (Example 1) Using a continuous horizontal electroplating apparatus shown in FIG. 1, a steel strip was electrogalvanized. The numbers in Figure 1 are dimensions
(mm). Plating was performed at a sheet passing speed of 10 m / min, and the limit current density and the occurrence of burning in the plating were examined.

[0028] Plating solution flow rate: 30 m / min (counter current) Plating material: Cold rolled steel plate (0.2 thickness x 1000 width mm) The perforated plate uses a 5 mm thick glass reinforced epoxy plate, and is divided into three zones from the energizing roll side Separate the opening ratio of the zone close to the energizing roll by 30%, the next zone by 40%, and 50%
The holes were drilled in this order.

The results of this example were as follows. The limit current density when the perforated plate was used according to the present invention was increased about 1.4 times as compared with the case where the perforated plate was not used. The occurrence of galvanizing burn was 85 A / dm ² when the perforated plate was used, and was 60 A / dm ^{2 when the} perforated plate was not used.

Example 2 In this example, nickel-zinc alloy electroplating was performed using the continuous horizontal electroplating apparatus shown in FIG. The numbers in the figure represent dimensions (mm). The composition of the deposited metal was determined when a perforated plate was used and when it was not used.

[0031] Current density: 80 A / dm ² Plating solution flow rate: 60 m / min (forward flow) Passing speed: 6 m / min Plating material: Cold rolled steel plate (0.6 thickness x 750 width mm) 10 mm thick acrylic as a perforated plate Drill a round hole in the plate and divide the area from the zone near the energizing roll to the farthest position into four parts, and set the aperture ratio to 25%, 35%, 45%, 55
The holes were adjusted in the order of% to adjust.

The results were as follows. The plating film was subjected to EPMA line analysis in the thickness direction. The results are shown in the graph of FIG. 3, where the Ni content in the plating film was 14.5 to 16% when the perforated plate was used in accordance with the present invention, but 12% when not used.
It varied greatly, up to 18%.

Example 3 In this example, molten salt Al-Mn alloy plating was performed in a vertical plating cell using a vertical plating apparatus shown in FIG. Was examined.

[0034] Plating conditions: temperature 200 ° C. Liquid speed 1 m / S (forward flow) Passing speed: 5 m / min A perforated plate was attached to the front of the anode electrode box corresponding to the cathode. The hole diameter was 5 mm, and the aperture ratio was divided into two, 30% and 45% from the top. The perforated plate and the electrode box were made of a 10 mm glass laminated polyimide plate.

The perforated plate of the comparative electrode box had a diameter of 6 mm.
Are provided with a constant aperture ratio of 50%. Electrode material: Al pellet (10 mm diameter) Plating material: SUS304 (0.4 mm thickness x 1000 mm width) As a result, when plating with an electrode box with a constant aperture ratio of 50%,
A current density of 50 A / dm ² burns occurred. When plating is performed with an electrode box whose opening ratio is adjusted to 30 or 45%, burning occurs at a current density of 65 A / dm ² , and it can be seen that adjusting the opening ratio is effective in increasing the limiting current density of plating.

FIG. 5 is a graph showing the results of the plating composition distribution. When the plating is performed using an electrode box having a constant aperture ratio, the Mn composition changes by 23 to 30% in the thickness direction of the plating. When plating was performed using an electrode box with an aperture ratio changed to 30 or 45%, the variation in Mn in the thickness direction of the plating was 24 to 28% with little variation, and there was an effect of adjusting the aperture ratio.

[0037]

By installing a perforated plate between the anode and the cathode in the electrolyzer for continuous electroplating, the limiting current density of the plating has been increased and high-speed plating has become possible.
In alloy electroplating, the composition variation in the thickness direction in the plating film can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one configuration example of an electroplating apparatus according to the present invention.

FIG. 2 is a schematic explanatory view showing the configuration of another example of the electroplating apparatus according to the present invention.

FIG. 3 is a graph showing the effect of the presence or absence of a perforated plate according to the present invention on the plating composition.

FIG. 4 is a schematic explanatory view showing the configuration of still another example of the electroplating apparatus according to the present invention.

FIG. 5 is a graph showing the effect of adjusting the aperture ratio of the perforated plate on the plating composition according to the present invention.

FIG. 6 is an explanatory diagram of a definition of an aperture ratio of a perforated plate.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hirohisa Seto 4-5-33 Kitahama, Chuo-ku, Osaka City Inside Sumitomo Metal Industries Co., Ltd. (72) Inventor Takeshi Hattori 4-5-33 Kitahama, Chuo-ku, Osaka City Within Sumitomo Metal Industries Co., Ltd. (72) Inventor Shigeo Itano 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City Inside Mitsubishi Heavy Industries Co., Ltd. No. Mitsubishi Heavy Industries, Ltd. Hiroshima Works

Claims (2)

[Claims] When performing electroplating on a continuously running material, a perforated plate made of an insulating material is placed between a material constituting an opposed cathode and an anode, and the perforated plate is formed along the material moving direction. A continuous electroplating method characterized in that the current density distribution in the material advancing direction is made uniform by adjusting the aperture ratio of the electrode. 2. An apparatus for electroplating a continuously running material, comprising an anode and a perforated plate provided between the anode and a passage area of the continuously running material, wherein the perforated plate is made of an insulating material. A continuous electroplating apparatus made, wherein an aperture ratio is adjusted in a material traveling direction.