JPS6026635A - Pb alloy for electrode for electroplating - Google Patents

Abstract

PURPOSE:To obtain a Pb alloy showing superior durability in an electroplating bath contg. sulfuric acid and exerting no unfavorable influence on deposition on a cathode during electroplating even when a very small amount of the alloy is dissolved, by adding specified amounts of Ag and/or Sn and Bi to Pb. CONSTITUTION:The composition of this Pb alloy for an electrode for electroplating is composed of 0.1-5wt% in total of Ag and/or Sn, 0.1-5wt% Si and the balance Pb with inevitable impurities. An insoluble anode made of the Pb alloy shows superior durability in an electroplating bath contg. sulfuric acid, and it exerts no unfavorable influence on deposition on a cathode during electroplating even when a very small amount of the alloy is dissolved in the electroplating bath to contaminate the bath.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pb gold alloy, particularly a pb alloy for electroplating electrodes.

Generally, when electroplating metal materials, an insoluble anode is used in an electroplating bath, and metals such as Zn, 5nSNi, Fe, Cu, and alloys thereof are applied to the surface of the metal material to be plated as a cathode. Electroplating is performed. As the insoluble anode at this time, for example, one made of Pb is used. This is because Pb has corrosion resistance against electroplating baths, and when electricity is applied during galvanizing, the surface is coated with lead oxide (hereinafter referred to as Pb).

2) is formed, and this Pbo2 functions as an insoluble anode.

However, it has been found that conventional insoluble anodes made of PB do not necessarily exhibit satisfactory durability (use life) because the PbO2 formed on the surface has weak adhesion to the PB substrate.

Therefore, in recent years, PBO2-coated insoluble anodes have been developed in which the surface of a substrate with excellent corrosion resistance such as Tt or Nb is coated with Pb0,2, and various alloy components have been developed to increase the adhesion of PBO2 to the Pb substrate. PB of various component compositions
Insoluble anodes made of alloys have been proposed, but in the former type of insoluble anodes, the pbo 2
There is a problem that the coating layer easily peels off, and the latter type of insoluble anode does not necessarily exhibit excellent durability, especially when used in a sulfuric acid electroplating bath. be.

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide a material for electroplating electrodes that eliminates the drawbacks of the prior art as described above, and in particular, to provide a material for forming an electroplating layer on the surface of a metal material to be plated in a sulfuric acid-based electroplating bath. An object of the present invention is to provide an insoluble anode material that exhibits excellent durability when used for

Therefore, the present inventors conducted research on pb alloy materials in order to achieve the above-mentioned purpose, and found that heg-Bi-Pb
It has been discovered that the Pb gold alloy of 5n-Bi-Pb type and 5n-Bi-Pb type pb gold alloys exhibits excellent durability in sulfuric acid-based electroplating baths, and even a small amount of dissolution does not have any adverse effect on electroplating deposition at the cathode. The invention has been completed.

Here, the gist of the present invention is that Ag
and one or two types of Sn in a total of 0.1 to 5.0%
, Bi: 0.1 to 5.0%, the balance being Pb and inevitable impurities.

It should be noted that it is already clear to those skilled in the art that the term "electroplating electrode" includes, for example, an electrode for electrolytic cleaning treatment as a pretreatment for plating.

The reason why the alloy composition is defined as above in the present invention will be explained below.

Ag is added to prevent PB dissolution in a sulfuric acid solution, and if it is less than 0.1%, it has no effect.
On the other hand, if it exceeds 5.0%, the effect will be saturated,
No further improvement is seen, and on the contrary, the material cost increases. Therefore, in the present invention, Ag is limited to 0.1 to 5.0%.

Bi is also added to prevent the elution of PB, and 0
．． If it is less than 1%, there is no effect, and on the other hand, if it exceeds 5.0%, no significant improvement effect is seen, but rather increases the material cost, further reduces the mechanical properties of PB, and makes the molding process difficult. Therefore, in the present invention, the amount of Bi added is limited to 0.1 to 5.0%.

Sn may be added instead of Ag, and its effect is equivalent to that of Ag. However, it is ineffective if it is less than 0.1%.
On the other hand, if it exceeds 5.0%, the effect will be saturated.

In the present invention, when Ag and Sn- are added, the total amount is 0.
Limit to 1-5.0%.

As described above, the insoluble anode made of the Pb alloy according to the present invention exhibits excellent durability in a sulfuric acid-based electroplating bath, and even if a small amount of dissolution contaminates the electroplating bath, it can be used as a cathode or electrode. It does not have any adverse effect on the electroplating deposition.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but each example is merely shown for illustrating the present invention, and the present invention is not limited thereto.

A Pb alloy molten metal having the composition shown in Table 1 was prepared using a conventional melting method and cast, and then rolled into a plate having a thickness of 1 mm. The thickness of the plate material obtained in this way is 1
A test piece with a length of 100 m was cut out, and this test piece was used as an anode, and the electrolytic area was 12
, 5 ca. On the other hand, a PT plate with the same dimensions as the anode was used for the cathode, and both plates were heated with a sulfuric acid-based mirabilite solution in which Na 2 SO4 was dissolved at a ratio of 100 g/β.
pH-2), bath temperature 70°C, applied current 10A.
(Current density: 80 A/dm2) and a current application time of 100 hours. After the test, Na1l (1
These test pieces were immersed in an aqueous solution in which 60 g/I- and 200 g/l of glycose were dissolved to remove the oxide film on the electrolytic surface of the test pieces. From the weight loss of the test piece at this time, the weight loss per unit electricity of the test piece was measured. These measurement results are also shown in Table 1.

Based on the measurement results shown in Table 1, Figure 1 shows the relationship between the Ag and Bi contents and the weight loss of the test piece.
FIG. 2 graphically shows the relationship between the Sn and Bi contents and the weight loss of the test piece.

As can be seen from these results, it can be seen that as the amounts of Bi and Sn added increase, the weight loss due to dissolution decreases significantly.

Sodo dish 1 This example shows the typical composition of the Pb alloy according to the present invention, 1% Ag, 5% Bi of test sample 16 in Example 1.
and for comparison purposes also test No.
, 13 and 13 containing only 1% of Ag, and by overlaying these Pb alloys on the surface of a carbon steel plate to a thickness of about 101 by Homoken processing,
Insoluble anodes for electroplating were manufactured, and then these insoluble anodes were applied to an electroplating bath on an actual production line to carry out galvanizing.

The bath composition for galvanizing is Zn304400g/R,N
a2S.

The pll of the a75g/I11 bath was 1.8 to 2.2, the bath temperature was 50±5°C, a cold rolled steel plate was used as the metal material to be plated, and the current density was 40 to 608/dm2.

Zinc plating was continued under these conditions, and the average depth of wear of the insoluble anode was measured after 6 months had passed. As a result, those using the alloy according to the present invention averaged 0.8 m
+a/A, Ilr and those using the comparative Pb alloy described above showed an average electrode weight loss of 3.0 A/A, Hr.

The insoluble anode made from the Pb alloy according to the present invention showed superior durability compared to the comparison electrode. Note that no adverse effect on galvanizing was observed during this period. on the other hand,
In the case of the comparative electrode, non-uniform deposits were observed in the plating layer.

Table 1 (continued on next page) (Continued from Table 1) (continued on next page) (Continued from Table 1) (Note) *Invention example

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the added amounts of Ag and Bi and the electrode weight loss; and FIG. 2 is a graph showing the relationship between the added amounts of Sn and Bi and the electrode weight loss. Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney Akira Hirose − Maku! Figure εt (η) Otsu°2 Figure Bi (γ)

Claims (1)

[Claims] In terms of weight %, 8g and Sn or 2 types of needles are 0.
A PB alloy for electroplating electrodes having a composition of 1 to 5.0% Bi, 0.1 to 5.0% Bi, and the balance PB and unavoidable impurities.