JPS62202094A - Production of gradient plating - Google Patents

Abstract

PURPOSE:To simplify an installation and to attain desired gradient plating by utilizing the difference in the deposition speeds of metals to change the bath compsn. between respective cells. CONSTITUTION:A plating stock soln. of Zn-Ni, etc., in a dissolution vessel 1 is introduced only into the 1st circulation tank 4a on the inlet side of plating and is circulated between the 1st plating cell 6a and the tank 4a by a pump 5a. The plating liquid in the tank 4a is allowed to overflow into the next tank 4b and is circulated between said tank and the 2nd plating cell 6b by a pump 5b and thereafter, the plating liquid is circulated between tanks 5c-5e and the respective corresponding cells 6c-6e as in the above-mentioned manner. A steel sheet is subjected to plating, then the plating liquid contg. Zn at a high rate and prepd. in the vessel 1 is introduced into the tank 4a and the Zn is taken much into the plating film. The bath compsns. nearer the tank 4e contain the Ni at the higher ratios. Then, the gradient plating film having continuously lower Zn content from the lower layer toward the upper layer of the film and conversely having successively higher Ni contents is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing gradient plating having a film composition in which the concentration changes continuously in the thickness direction of the plating film.

(Conventional technology) Conventionally, in order to manufacture a multilayer plating film with two or more layers,
Two or more independent raw material supply systems such as circulation tanks and raw material supply equipment must be used, which poses problems in bath management.

For this reason, a method of forming iron-zinc alloy plating layers with different iron contents using the same plating solution was proposed in JP-A-58-
This is proposed in Japanese Patent No. 77589. This is simply
By changing the flow rate and/or current density of the plating solution in each plating bath into which the plating solution of the system is introduced,
This is to form plated layers with significantly different iron contents.

Furthermore, a method for manufacturing an iron-zinc alloy multilayer plating in which the zinc content is sequentially decreased or increased by sequentially changing the current density between each plating bath is disclosed in Japanese Patent Laid-Open No. 58-67886. ing.

(Problems to be Solved by the Invention) The above method can obtain a desired multilayer plating film while using a single plating solution, but if the current density is changed between each plating tank, The optimum plating conditions (for example, threading speed and current density) will be deviated from, and the amount of plating deposited will decrease accordingly, so in order to maintain the same plating thickness, the threading speed will have to be lowered, resulting in a reduction in production volume. There is a problem that causes In addition, the control devices for controlling current, threading speed, etc. for these various types have also become complicated.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention focuses on the fact that there is a difference in the deposition rate of different metals in the plating solution. This paper proposes that the bath composition of each type be changed using the method, and thereby gradient plating with different film compositions can be performed continuously.

To explain in more detail, Ni-Zn, Fe-Zn
When plating, etc., the precipitation rate of Zn is faster than that of Ni + Fe. For this reason, if raw materials are not replenished, Z
The bath composition changes to a lower ratio of n, and the composition of the formed film also becomes lower in Zn content. By utilizing this, it is possible to continuously change the film composition.

Therefore, according to the present invention, in the electroplating line,
By replenishing raw materials from only a portion of the multistage baths, the bath composition between each bath is continuously changed, thereby providing a method for producing graded plating with successively different coating compositions.

An example of plating equipment for carrying out the present invention is shown in FIG. The equipment shown in Figure 1 has a lower layer containing Zn-rich Nt-Z.
This is a product that cannot be used to manufacture n-plated steel sheets.

In the dissolution tank 1, for example, Zn:N1=88:12
The raw materials are added at a ratio of 1, and the plating stock solution prepared by being dissolved by the stirring blade 2 is introduced into the first circulation tank 4a on the plating input side by the bomb f3. The plating solution introduced into the first circulation tank 4a is circulated between the first mesquicell 6a and the circulation tank 48 by the pump 5a. The plating solution in the first circulation tank 4a overflows into the second circulation tank 4b, and the plating solution overflowed and introduced into the second circulation tank 4b is circulated between the second mesh cells 68 by the bomb f5b. Similarly, the plating solution in the second circulation tank 4b sequentially overflows to the third to fifth circulation tanks 50 to 5e, and is circulated between the corresponding mesh cells 60 to 60 by the respective bombs 7' 5c to 5e. It has become.

Now, in the above-mentioned equipment, if a steel plate P is to be plated, a plating solution with a high Z11 content prepared in the dissolution tank 1 is introduced into the first circulation tank 4a. Since a large amount of Ni is incorporated into the plating film, the Ni
The bath composition has a high content. In this way, a plating film is formed in which the Zn content is continuously low and the Ni content is successively high from the lower plating film layer to the upper plating film layer.

Therefore, for example, a lower layer Zn-rich Ni-Zn plated steel sheet (
For example, it is possible to manufacture an upper layer with a Ni content of 16% and a lower layer with a Ni content of to%.

As the plating operation conditions, current density, flow rate, etc. can be kept unchanged. Therefore, the disadvantage of high cost due to changing the current density can be overcome.

In the above example, the case where the method of the present invention is applied to Ni-Zn plating is shown, but the present invention can be applied to Ni-Zn plating as well as
It can also be used for Fe-Zn, 5u-Pb plating, etc.

Various concentrations can be controlled by changing the amount of liquid circulated. In addition, if it is a closed system, only the amount to be plated needs to be input. The amount of input can be made proportional to the amount of electricity.

In the case of the above example, for example, Zn: 88kli
'/H.

If 9/H plating is to be performed on Nt:12, the same amount of metal may be added.

Furthermore, by slowing down the circulation speed, it is possible to create large differences in concentration between each species.

(Function) As described above, since the present invention utilizes the difference in deposition rate depending on the metal, it is possible to continuously produce graded plating with different plating film compositions using a single raw material supply system.

(Example) Operating conditions Plated bundle material: Thickness 0.8, width 1200m+n cold rolled steel plate Passing speed near 0m/min Test equipment: Use the one shown in Figure 2 Current density: 60 A/dm2 Plating o ,: P containing 2n++ and Ni++ in the form of sulfate
H:2. Temperature: 50°C Bath composition: Plating film: Plating thickness (coating amount): 1o, p/1xz (both sides) Product evaluation: Good corrosion resistance (equivalent to plating containing 15% Ni), good workability, good pitting resistance (invention) Effects) As described above, according to the present invention, the equipment can be simplified,
A desired graded plating can be achieved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus for carrying out the present invention, and FIG.
The figure is a schematic explanatory diagram of the test device of the present invention. 1... Dissolution tank, 2... Stirring blade, 3... Pump,
4a-4e...Circulation tank, 5a-5e...Bonde, 6a-6e...Metsukicel, P...Steel plate.

Claims (1)

[Claims] (1) In an electroplating line, the bath composition between each tank is continuously changed by replenishing raw materials from only a part of the multi-stage tank, and as a result, the film formation composition is continuously changed. Inclined plating manufacturing method.