JP2764337B2 - Ni or Ni-Zn alloy or Ni-Zn-Co alloy plating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a Ni or Ni-Zn alloy or Ni-Zn-Co
In the process of applying alloy plating, Ni or Ni-Zn alloy or Ni or Ni-Zn alloy supplied to the plating bath while continuously and controlling only the reduced amount of Ni ions to be plated without changing the component concentration in the plating bath solution or The present invention relates to a Ni-Zn-Co alloy plating method.

[Conventional technology]

In nickel plating, electroplating is usually performed using an insoluble anode.
Ni ions are consumed. For this reason, these Ni
In general, a method of supplying industrial reagents such as Ni carbonate, nitrate, sulfate, and hydroxide to a plating tank for the purpose of supplying ions. However, because this reagent is in powder form,
Since the supply method is intermittent and an amount of acid is consumed due to the dissolution of the reagent, control and management of the solution concentration is difficult and time-consuming.

As a method of supplying such Ni ions, an anode chamber in which a nickel elution anode (nickel anode) is present and a cathode chamber in which a counter electrode (cathode) is present are separated by an ion exchange membrane in an anode chamber of a nickel elution electrolytic cell. The plating bath solution is circulated from the plating bath, while the cathode chamber is filled with an electrolyte solution such as salt and energized, and nickel ions are eluted from the nickel elution anode, without disturbing the balance of other plating bath compositions. A method of supplying a reduced amount of Ni ions by plating has been proposed (Japanese Patent Laid-Open No. 60-12 / 1985).
No. 1299).

[Problems to be solved by the invention]

The solution composition is a sulfuric acid solution containing Ni or Ni, Zn or Ni, Zn, Co, and the electrolytic solution in the cathode chamber is sulfuric acid, and hydrogen ion selective permeable cations which are considered to be preferable for performing electrolysis Using an exchange membrane (see JP-A-60-121299)
In this case, the permeation amount of hydrogen ions from the anode chamber to the cathode chamber is about 40% of the amount of electricity, so the electrolysis efficiency is poor and the hydrogen ion concentration in the anode chamber increases. I do. As described above, in the solution composition, when supplying Ni ions while plating, power efficiency is increased due to poor current efficiency, and the hydrogen ion concentration in the anode chamber is increased, thereby deteriorating plating properties. There are problems.
Therefore, there is a need to remove hydrogen ions from the anode compartment and to facilitate the transfer of ions between the anode compartment and the cathode compartment.

In the plating tank, hydrogen ions are generated by electrolysis of water accompanying plating, so that the concentration of hydrogen ions in the solution increases. Also, it has been found that the hydrogen ion concentration in the solution greatly affects the plating properties.

On the other hand, in the cathode chamber, hydrogen ions decrease due to generation of hydrogen gas at the cathode. Since the consumed Ni ions and the supplied Ni ions are the same, the amount of plating current and the amount of electrolysis current are equal, and the amount of increase in hydrogen ions in the plating bath and the amount of decrease in the cathode compartment of the electrolytic cell are cancelled. Is done. However, in actuality, the amount of hydrogen ions permeating the ion exchange membrane as described above is as small as about 40% of the amount of electricity, so that the hydrogen ion concentration in the cathode chamber increases. In addition, since the cation exchange membrane is selectively permeable to hydrogen ions, there is no movement of ions other than hydrogen ions, and the electrolysis efficiency is poor.

As described above, when Ni or Ni, Zn or Ni, Zn, Co is electrolyzed with sulfuric acid as the electrolyte solution of the cathode compartment using a sulfuric acid solution containing Ni, Zn, Co, hydrogen ions are removed from the plating bath and the anode compartment of the electrolytic bath. There is a need to remove and facilitate the transfer of ions between the anode and cathode compartments.

The present invention provides a method for reducing the concentration of a solution over a long period of time without deteriorating the plating properties due to an increase in hydrogen ions in the plating tank and reducing the electrolysis efficiency due to the small movement of ions between the anode chamber and the cathode chamber. The purpose of the present invention is to enable stable plating by controlling the temperature.

[Means for solving the problem]

As the electrolysis proceeds, the hydrogen ions are consumed as hydrogen ions are released as hydrogen gas in the cathode chamber, while the hydrogen ion concentration increases in the plating tank. Further, since the amount of Ni consumed and the amount of Ni generated are equal, the plating current amount and the electrolysis current amount are equal, so that the hydrogen ion concentration that increases in the plating tank and the hydrogen ion concentration that decreases in the cathode chamber of the electrolytic tank are: equal.

Therefore, the present invention provides a solution in which the hydrogen ion concentration in the cathode chamber of the electrolytic cell is lower than the hydrogen ion concentration in the plating tank and a solution in the plating tank in which hydrogen ions are generated. A diffusion dialysis tank (manufactured by Asahi Glass Co., Ltd.) that performs diffusion dialysis using the difference in the concentration of hydrogen ions generated at the boundary of the anion exchange membrane as a driving force by allowing the solution in the plating tank and the solution in the cathode chamber of the electrolytic tank to pass through each other. The hydrogen ions in the solution in the plating tank are transferred to the cathode chamber on the electrolytic cell side as sulfuric acid, and the solution in the plating bath is circulated to the plating tank, the solution in the cathode chamber of the electrolytic tank is circulated to the cathode chamber, and The use of an anion exchange membrane, which facilitates the transfer of sulfate ions, between the anode and cathode compartments of the anode controls changes in hydrogen ion concentration due to electrolysis, thereby reducing plating properties and reducing electrolytic efficiency. Without reduction, it is to provide a method which enables stable plating for a long time. In the anion exchange membrane used between the anode chamber and the cathode chamber, sulfate ions and hydrogen ions permeate, and the supply amount of Ni ions is 90 to 100% with respect to the amount of electricity. Further, since an anion exchange membrane is used in the electrolytic cell and the diffusion dialysis cell, the amount of cations other than hydrogen ions is so small as to be negligible.

〔Example〕

The present invention is described in detail in the following examples. As schematically shown in FIG. 1, the outline of the system is such that the anode chamber a of the electrolytic cell A is connected to the plating cell B, and the diffusion dialysis cell C is the plating cell B.
And the cathode chamber b of the electrolytic cell A, so that the respective solutions circulate. As shown in FIG. 2 for details of the electrolytic cell A, an anode 1 and a cathode 9 are provided via an anion exchange membrane 3, and the solution is supplied to the respective chambers via inlets 5 and 6. Flow into cell, outlet
It is a structure that flows out of the cell through 7, 8 and is about 5 cm thick
100 cells are arranged in parallel with each cell as one unit, and a current flows to DC. The anode chamber a of the electrolytic cell A is provided with a basket-type anode 1 made of Ti, into which a spherical Ni pellet 2 having a diameter of about 5 to 10 mm can be put.
In addition, the structure is such that the pellet is not detached from the basket-type anode even if the pellet is reduced by electrolysis. It is preferable that the Ni pellets 2 contain an appropriate amount of sulfur. However, if the sulfur affects plating properties, Ni pellets having a low sulfur content may be used. As the Ni source, spherical Ni pellets were used in order to increase the surface area as much as possible. However, a plate-shaped or rod-shaped Ni source may be used. On the other hand, in the cathode chamber b, an electrode having a low hydrogen overvoltage is preferable so that metal ions mixed as impurities in the solution are unlikely to be deposited on the cathode. In the embodiment, a stainless steel electrode is used as the cathode 9. . One of the diffusion dialysis tanks C using the anion exchange membrane 4 is connected to the plating tank B, and the other is connected to the cathode chamber b of the electrolytic cell A. Here, the first solution is nickel sulfate, zinc sulfate, cobalt sulfate,
The composition was adjusted to the composition shown in Table 1 with sulfuric acid, and the consumption of zinc and cobalt by plating was replenished as necessary by adding industrial reagents. The conditions for plating and electrolysis are as shown in Table 2.

Hereinafter, the operation of each tank will be described. First, the case where diffusion dialysis is not performed will be described with reference to FIG. When a current is applied to the electrolytic cell A, hydrogen is generated from the cathode, and the hydrogen ion concentration corresponding to the amount of electricity supplied at this time decreases. On the other hand, in the plating tank B, water is decomposed at the cathode to generate oxygen gas. At this time, hydrogen ions are generated at the same time, so that the hydrogen ion concentration increases. Since this solution is circulating with the anode chamber a of the electrolytic cell A, a concentration difference occurs between the anode chamber a and the cathode cell b of the electrolytic cell A with the anion exchange membrane 3 as the plating and electrolysis proceeds. Eight hours after the energization, the hydrogen ion concentration was as shown in Table 3, and the electrolysis hardly proceeded, and the properties of the plating deteriorated.

Next, the case where the diffusion dialysis is operated will be described. As described above, as the plating proceeds, the hydrogen ion concentration increases in the plating tank B. However, if the initial concentration of sulfuric acid is set lower in the cathode chamber b of the electrolytic tank A, the diffusion dialysis tank C A difference in hydrogen ion concentration occurs at the boundary of the anion exchange membrane 4. This becomes the driving force, and the sulfuric acid diffuses to the low concentration side as shown by the arrow D. As a result, the desulfurized solution is returned to the plating tank B as shown by the arrow E. The solution in which the sulfuric acid is diffused is returned to the chamber b as shown by an arrow F. At this time, since the anion exchange membrane 4 is used in the diffusion dialysis tank C, Ni, Zn, and Co ions hardly enter the low concentration solution side. The concentration of sulfuric acid to be diffused depends on each hydrogen ion concentration in the plating chamber B and the cathode chamber b of the electrolytic cell A and the flow rate of the circulating solution. What is necessary is just to determine by performing. Here, the hydrogen ion concentration and the Ni, Zn, and Co concentrations in each tank when the continuous operation was performed for about 8 hours, as set in Table 4, were shown. As is clear from Table 4, there is almost no change in the concentration of the metal element and the hydrogen ion in each tank, indicating that the Ni ions were supplied stably.

[Effects of the Invention] An increase in the concentration of hydrogen ions generated by plating is removed from the plating tank using a diffusion dialysis tank, and the amount of hydrogen ions reduced due to electrolysis can be replenished by the sulfuric acid. The concentration of hydrogen ions is always constant, and the ion transfer between the anode and cathode chambers is facilitated and the electrolysis efficiency is good, so that a stable plating operation can be performed for a long time. In addition, since sulfuric acid can be recovered and supplied to the cathode of the electrolytic cell for reuse, the operation can be performed at a lower cost than in the case where sulfuric acid is newly replenished.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the method of the present invention using a diffusion dialysis tank, FIG. 2 is an explanatory view of a configuration example of the electrolytic cell of FIG. 1, and FIG. 3 is an explanatory view of a comparative method without using a diffusion dialysis tank. . A: electrolytic cell, B: plating cell, C: diffusion dialysis cell, D: arrow, E: arrow, F: arrow, a: anode chamber, b: cathode chamber, 1: anode, 2: Ni pellet, 3: shade Ion exchange membrane, 4: anion exchange membrane, 5: inlet,
6: inlet, 7: outlet, 8: outlet, 9: cathode.

Claims (1)

(57) [Claims] An Ni or Ni-Zn alloy or a Ni-Zn-Ni-Zn alloy is charged into a cathode chamber of a Ni eluting electrolytic cell in which an anode chamber in which a Ni eluting anode is present and a cathode chamber in which a counter electrode is present are partitioned by an ion exchange membrane. Co
From the alloy plating bath, a plating bath solution consisting of a sulfuric acid solution containing Ni or Ni, Zn or Ni, Zn, Co is circulated, while the cathode chamber is filled with a sulfuric acid solution and energized, and Ni ions are plated from the Ni eluting anode. Ni or Ni-Zn alloy or Ni-Zn- which replenishes the bath solution and refluxes the solution having an increased Ni ion concentration to the plating tank.
In the Co alloy plating method, an anion exchange membrane is used as the ion exchange membrane of the electrolytic cell, and the sulfuric acid concentration of the cathode chamber of the electrolytic cell is set lower than the sulfuric acid concentration of the plating bath solution of the plating tank. The plating bath solution is circulated in one compartment of the diffusion dialysis tank partitioned by the membrane, the solution in the cathode compartment of the electrolytic cell is circulated in the other compartment, and the solution in one compartment which has been desulfated by sulfuric acid diffusion. To the plating bath, Ni or Ni-Zn alloy or Ni-Zn- characterized by refluxing the solution in the other compartment sulfurized by sulfuric acid diffusion to the cathode compartment of the electrolytic bath
Co alloy plating method.