JPS6045718B2 - Electrode for plating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a durable insoluble electrode for plating in a sulfuric acid bath system.

PbO is formed on a Pb (lead) surface in a plating solution for electrolytic treatment of metal surfaces, for example, as a plating electrode in a continuous electroplating line for copper plates.

(lead dioxide) as an anode, generally Pb
has been used directly. However, H.O. Since it has internal strain, it easily peels off from the Pb surface, which poses a problem in the durability of use as an anode. As a countermeasure for this, conventionally, 0.01% of Ag (silver) or Sn (tin) was added to Pb.
Lead alloys to which approximately 10% of lead has been added have been used. In this case, the function of Ag and Sn(7) in Pb02 is Pb
By the elements of Ag and Sn entering the voids between the constituent particles of ()O, the spaces between the particles are covered with a film of these elements, and as a result, the entire constituent particles of PbO2 are protected by the formed film. There are many things. pbO also by adding Ag and Sn. The durability against the plating solution was not sufficient, and there were problems in the time and cost required for replacing the anode. Other plating electrodes include Ti
(Titanium) based Pt (platinum) plated anodes or Pt clad anodes are known, but the former has poor durability considering its price, and the latter is very expensive, so it cannot be used in reality. There were drawbacks such as the inability to do so. On the other hand, in order to improve the durability of P darkening, Te (tellurium) was added to Pb.
Various studies have been conducted on the effects of adding elements such as Sb (antimony), As (arsenic), Ag, and Ti (thallium). According to those studies, Ag
-Te-P dark combination: Ag: 2% and Te: 10-15%
However, it is reported that it is difficult to incorporate Te into Pb in a similar manner. Also Ag-Sb
Regarding -P darkening, the addition of Ag has an effect on corrosion resistance, but even when Ag-Sb is used in combination, the effect of Sb addition is not observed. Furthermore, for As-Ti-Pb alloy, T
Cases have been reported in which As reduces the durability improvement effect of i. A complete solution to the above-mentioned problems has not yet been found, and at present Pb alloys to which Ag or Sn is added are used. In order to solve this problem, the present inventor conducted experimental research on the elements added to the Pb alloy, and found that a Pb alloy containing T1 or '11 and Ag within the range described below has excellent durability. We found that this shows that

The present invention has been made based on this knowledge, and it is an object of the present invention to provide a highly durable, ie, insoluble, sulfuric acid bath-based plating electrode that can be used in practice.

The plating electrode according to the present invention is characterized by being made of an η--Pb alloy containing 0.8-6% TI and 0.3-6% Ag. The reason for limiting the content of 1, Tl, and Ag as described above is based on the following experimental results.

First, the experimental conditions and results will be explained below. Samples include samples with compositions as shown in Table 1 (No. 1~
No. 45) and samples having compositions as shown in Table 2 (No. 46 to No. 5O) were used as comparative samples. The above sample was mixed with sulfuric acid acidic mirabilite solution (Na2SO4:20
Electrolysis is performed by applying a current of 10 A using a rectifier using Pt as an anode and a counter electrode in a solution adjusted to PH=2 at a temperature of 70° C. The current density as the electrolytic conditions is 80 A/DTl, and the electrolytic time is an intermittent supply in which the current is applied for 10 hours and the electricity is stopped for 1 hour. and 110C
After the corrosion resistance test between @, the sample was taken out from the sodium sulfate solution,
The oxide film formed on the surface of the sample was dissolved in a solution consisting of 200 g/' of NaOH: 16 da/f glycose, and the weight loss after 110 (b), that is, corrosion, was determined by measuring the weight of the sample before and after the corrosion resistance test. The amount was investigated.

Tables 1 and 2 show the composition [%] of each sample. In addition to the amount of corrosion [M
9] was shown. Figure 1 shows No. 1 in Table 1. l~NO. lO
and NO24eK in Table 2. Figure 2 shows NO.2 in Table 1. ll~
No. 45 and No. 47 to No. 4 in Table 2. The experimental results for 5O are shown with the amount of corrosion taken on the vertical axis and the addition ratio of T1 on the horizontal axis. In Fig. 2, the x point (connected by the broken line) is a sample piece with an Ag addition ratio of 0.05%, the Δ point (connected by the broken line) is also for a sample with an Ag addition rate of 0.1%, and the Δ point (connected by the solid line) is also 0. .3%, O point (solid line connection) is 1.0%, × point (solid line connection) is also 5.0%, ◎ point (
The solid line connection) shows the results for the same 6.0% case, and the O point (broken line connection) shows the results for the same 10% case. From Figure 1, when the addition ratio of Tl is 0 to 0.8%, the amount of corrosion tends to decrease significantly as the addition ratio increases, but when the addition ratio exceeds 6%, On the contrary, the amount of corrosion tends to increase, and the addition ratio of the mound is 0.8 to 6.
% range shows an excellent effect on corrosion resistance. In addition, No. 1 in Table 1. l~NO. Regarding the sample of 1O, if the addition ratio is in the above range of 0.8 to 6%, sample N
O. I marked the column with a ●. Also, from Figure 2, the addition ratio of 1 in the range of 0.8 to 6% is excellent in corrosion resistance, and A
? If the addition ratio is less than 0.3% or more than 6%, the effect on corrosion resistance is low;
It can be seen that the range of % is excellent. No. 1 in Table 1. l
l~NO. Sample No. 45 has the addition ratio of η and N within the above range. Marked A in the column. Next, another demonstration example of the above results will be shown.

The samples include Ag-Pb alloy containing 1% Ag, which is generally used as a plating electrode, and T1-Ag-P alloy containing 1% Ag and T1:1% according to the present invention.
Each of the b alloys is deposited on the iron base material by homogenization to approximately 1
Two types of lining with a thickness of 0m1n are used.
The amount of corrosion was investigated when the above sample was used as an anode for electrogalvanizing for half a year under operation at a current density of 40 A/Dm2. Table 3 shows the results as the amount of decrease in linin thickness over half a year. From this table,
It can be seen that the Tl-Ag-Pb alloy has a durability of about 4 times higher than that of Ag-P dark gold. Furthermore, when using a Pb electrode, it is common for missing PlO2 to adhere to the copper plate to be plated and being pushed in by the rolls that transport the steel plate, but when using the electrode of the present invention, There are none.

Furthermore, when the electrode of the present invention is used, the elution of P-4 into the galvanizing bath solution can be prevented, so the appearance of the plated product is improved, and the corrosion resistance is also improved accordingly. The electrode of the present invention is not limited to electroplating, but can also be used as an anode in fields such as electrolytic refining of zinc, where the electrochemical anode reaction is the same.

As detailed above, according to the present invention, T1-Pb alloy or T
By using 1-P metal, the corrosion resistance of the electrode is greatly improved, and the work time and cost required for replacing the electrode can be significantly reduced, compared to those using Pt etc. The present invention has excellent effects such as being extremely inexpensive and long in practical use.

[Brief explanation of drawings]

Figure 1 shows the experimental results regarding the complex addition ratio and corrosion amount of Tl-Pb alloy, and Figure 2 shows the A of T1-Ag-Pb alloy.
3 is a graph showing experimental results regarding the feather addition ratio and the amount of corrosion, using the g addition ratio as a variable.

Claims (1)

[Scope of Claims] 1. An insoluble electrode for sulfuric acid bath-based plating, characterized in that it contains 0.8 to 6% Tl, with the remainder consisting of Pb and impurities. 2 Contains 0.8 to 6% Tl and 0.3 to 6% Ag,
An insoluble electrode for plating in a sulfuric acid bath, characterized in that the remainder consists of Pb and impurities.