JP5505213B2 - Electrical nickel plating equipment for steel strip - Google Patents

Description

  The present invention relates to an electric nickel plating facility for a steel strip that is subjected to electrolytic nickel plating after pickling the surface of the steel strip.

  When electroplating the surface of the steel strip, as shown in FIG. 4 (a), first, the steel strip 1 is immersed in a pickling line tank 2 filled with a pickling solution such as sulfuric acid to perform the pickling. The excess acid adhering to the steel strip surface is removed by the rinse tank 3, and then the steel strip is immersed in the nickel line tank 4 to perform electro nickel plating.

  In the nickel line tank 4, the steel strip 1 is conveyed in the nickel line tank by the energizing roll 5 and the sink roll 6, and nickel plating is performed by energizing a plurality of electrodes 7 installed so as to sandwich the steel strip. . As the electrode, a titanium mesh basket filled with nickel pellets of about 10 to 30 mmφ is used. As the plating bath, for example, a plating bath called a watt bath is used.

  When nickel plating is applied to a steel strip, sludge is generated on the electrode surface. Since sludge increases the electrical resistance of the electrode and hinders the productivity of plating, it is necessary to remove this sludge. In Patent Document 1, the plating bath in the nickel line tank is once discharged out of the system, an acid capable of dissolving the sludge is supplied, the sludge deposited inside the electrode is dissolved and discharged out of the system, and the sludge is discharged. An apparatus for removal is disclosed. As shown in FIG. 4B, sulfuric acid is used as an acid for dissolving sludge, and the sulfuric acid cleaning liquid circulation tank 12 and the nickel line tank 4 are circulated. The sulfuric acid used for sludge dissolution is discarded every time.

Japanese Patent No. 3909041

  In the nickel electroplating line, immersion pickling was used as described above for pickling before plating. On the other hand, the demand for multi-layer plating is growing as a high-grade nickel-plated steel sheet, and an improvement in pickling ability is required in order to remove the oxide film on the lower layer plating and ensure adhesion of the upper layer plating. In such a case, it is preferable to apply electrolytic pickling instead of immersion pickling which has a weak pickling ability. In the electrolytic pickling, a lead electrode is provided in the pickling line tank as an electrode, sulfuric acid is used as the pickling liquid, sulfuric acid is accommodated in the electrolytic pickling liquid circulation tank, and the sulfuric acid pickling is performed between the pickling line tank and the pickling line tank. Circulate liquid.

  In the electrolytic pickling, a sulfuric acid pickling solution is circulated and used repeatedly. On the other hand, sulfuric acid was also used to dissolve sludge in the nickel line tank, and the sulfuric acid dissolved in the sludge was discarded every time. Since both use sulfuric acid, it is preferable if sulfuric acid for electrolytic pickling and sulfuric acid for dissolving sludge can be shared. Further, it is preferable that the sulfuric acid for dissolving sludge is not discarded every time but can be used repeatedly.

  However, electrolytic pickling was used for pickling in nickel electroplating, sulfuric acid for electrolytic pickling and sulfuric acid for dissolving sludge were shared, and the shared sulfuric acid was repeatedly used. Quality anomalies due to lead adhesion on the surface.

  The present invention solves the above-mentioned problem, uses electrolytic pickling for pickling in electro nickel plating, shares sulfuric acid for electrolytic pickling and sulfuric acid for dissolving sludge, and repeatedly uses sulfuric acid for dissolving sludge. An object of the present invention is to provide an electric nickel plating facility for steel strip.

That is, the gist of the present invention is as follows.
A pickling line tank 2 for pickling the surface of the steel strip and a nickel line tank 4 for performing electro nickel plating on the surface of the steel strip. After pickling the steel strip 1, the surface of the steel strip is subjected to electro nickel plating. An electric nickel plating facility for the steel strip to be applied,
It has a sulfuric acid cleaning device 10 for removing sludge accumulated on the electrode 7 disposed in the nickel line tank. When performing sulfuric acid cleaning, sulfuric acid is circulated in the nickel line tank using the sulfuric acid cleaning device 10.
The pickling line tank 2 performs electrolytic pickling, and has an electrode 9 for electrolytic pickling in the pickling line tank. During the electrolytic pickling, the sulfuric acid contained in the electrolytic pickling solution circulation tank 11 is pickled. Circulating in the line tank,
Using sulfuric acid stored in the electrolytic pickling liquid circulation tank 11 as sulfuric acid used in the sulfuric acid cleaning device 10,
An electric nickel plating facility for a steel strip, wherein an electrode obtained by plating platinum on the surface of a titanium substrate is used as the electrode 9 for electrolytic pickling.

  The present invention has a pickling line tank for pickling the surface of the steel strip and a nickel line tank for performing electro nickel plating on the surface of the steel strip, and sludge deposited on electrodes disposed in the nickel line tank. In the steel nickel electroplating facility, which has a sulfuric acid cleaning device for removing the steel strip and then electroplating the steel strip surface after pickling, the electrolytic acid pickling is carried out in the pickling line tank. By using an electrode with platinum plated on the surface of the titanium base as an electrode for washing, it is possible to share sulfuric acid for electrolytic pickling and sulfuric acid for dissolving sludge, and it is also possible to repeatedly use sulfuric acid for dissolving sludge. High nickel plating quality.

It is the schematic which shows an example of the electro nickel plating equipment of this invention. It is the schematic which shows the operation | movement condition of the electro nickel plating equipment of this invention. It is the schematic which shows the operation | movement condition of the electro nickel plating equipment of the comparative example which used the electrolytic pickling and used the lead electrode for the electrolytic pickling electrode. It is the schematic which shows the operation | movement condition of the electro nickel plating equipment of the prior art example using immersion pickling.

  The electric nickel plating facility of the present invention will be described with reference to FIGS.

  The electric nickel plating equipment of the present invention has a pickling line tank 2 for pickling the steel strip surface and a nickel line tank 4 for applying electric nickel plating to the steel strip surface, and pickling the steel strip 1. Later, electronickel plating is applied to the surface of the steel strip.

  In the present invention, electrolytic pickling is performed in the pickling line tank 2. The pickling line tank 2 has an electrode 9 for electrolytic pickling, and sulfuric acid stored in the electrolytic pickling solution circulation tank 11 is circulated in the pickling line tank 2 during electrolytic pickling. By changing from the conventional immersion pickling to electrolytic pickling, the pickling ability is improved, so that it is possible to remove the oxide film on the lower layer plating and ensure the adhesion of the upper layer plating in the multilayer plating.

  The present invention also includes a sulfuric acid cleaning device 10 for removing sludge accumulated on electrodes arranged in the nickel line tank 4. When nickel electroplating is applied to the steel strip 1, the nickel line tank 4 is filled with a nickel plating bath. As the plating bath, for example, a plating bath called a watt bath is used. When the sulfuric acid cleaning is performed, the nickel plating bath in the nickel line tank is removed, and instead, sulfuric acid is circulated in the nickel line tank using the sulfuric acid cleaning device 10. The sludge deposited on the electrode is dissolved in sulfuric acid and the sludge is removed from the electrode.

  Further, in the present invention, sulfuric acid stored in the electrolytic pickling liquid circulation tank 11 is used as sulfuric acid used in the sulfuric acid cleaning device 10. Thereby, the sulfuric acid used for electrolytic pickling and the sulfuric acid used for sulfuric acid cleaning can be shared. And it is used repeatedly, without discarding sulfuric acid for every sulfuric acid washing.

  FIG. 3 shows a comparative example in which electrolytic pickling is used for pickling in electro nickel plating, and sulfuric acid for electrolytic pickling and sulfuric acid for dissolving sludge are shared, and the shared sulfuric acid is repeatedly used. In FIG. 3, a lead electrode 8 is used as an electrode for electrolytic pickling. As described above, in the comparative example shown in FIG. 3, quality abnormality due to adhesion of lead occurs on the surface of the steel strip after nickel plating. Since tin was not detected in the lead adhesion part, it was found that the solder joint in the plating facility was not dropped and adhered. If it does so, the lead electrode 8 in electrolytic pickling is assumed as a lead source of a quality abnormal part. On the other hand, when the lead adhesion part of the plated steel plate was observed, lead was adhered to the upper layer of the Ni plating layer. Therefore, it can be seen that lead did not adhere before nickel plating, but after nickel plating. If it does so, the lead did not adhere to the steel strip in the pickling line tank 2 but adhered after nickel plating in the nickel line tank 4.

  In the electric nickel plating facility of the comparative example shown in FIG. 3, when nickel plating is applied to the steel strip 1, as shown in FIG. 3 (a), an electrolytic pickling solution circulation tank is used using an electrolytic pickling solution circulation path 21. 11 and the pickling line tank 2 circulate between the pickling solution and the plating solution circulates between the plating solution circulation tank and the nickel line tank 4 using the plating solution circulation path 23. When the sludge in the nickel line tank 4 is dissolved, as shown in FIG. 3B, the plating solution in the nickel line tank 4 is removed, the sulfuric acid cleaning device 10 is operated, and the sulfuric acid cleaning liquid circulation path 22 is removed. Then, sulfuric acid circulates between the electrolytic pickling liquid circulation tank 11 and the nickel line tank 4. From the above facts, as shown in FIG. 3 (a), when the electrolytic pickling is performed, lead is dropped from the lead electrode 8 of the electrolytic pickling and mixed in sulfuric acid, and then as shown in FIG. 3 (b). When the nickel plating electrode was washed with sulfuric acid, lead in sulfuric acid was carried into the nickel line tank 4, and when this was followed by nickel plating of the steel strip, this lead adhered to the steel strip after nickel plating. To be estimated.

  A Watt bath is used as a nickel plating bath used for electro nickel plating. The Watt bath contains nickel chloride. As shown in FIG. 3B, when the sulfuric acid cleaning of the nickel line tank 4 is performed, the sulfuric acid in the electrolytic pickling solution circulation tank 11 is circulated after discharging the nickel plating bath. At this time, a small amount of chloride ions in the nickel plating solution are mixed in the sulfuric acid. Next, as shown in FIG. 3A, when pickling is performed in the pickling line tank 2 using sulfuric acid in the electrolytic pickling solution circulation tank 11 mixed with chloride ions, pickling solution is obtained. The surface of the lead electrode 8 is etched by the chloride ions therein, and as the etching progresses, the lead is damaged and dropped, and lead is mixed in the pickling solution. It is presumed that this mixed lead led to lead adhesion on the surface of the plated steel sheet.

  Therefore, in the present invention, instead of the lead electrode 8, as shown in FIGS. 1 and 2, an electrode 9 in which platinum is plated on the surface of the titanium base material is used as an electrode used in the electrolytic pickling. Platinum plating may be performed only on the surface of the electrode 9 that faces the steel strip. Neither titanium nor platinum is etched on the surface even when in contact with pickling solution containing chloride ions, so that no quality abnormality occurs when a lead electrode is used. In addition, if platinum plating is performed on the side of the electrode 9 facing the steel strip 1, the electrode can be manufactured at low cost.

  According to the present invention, as a result of applying electrolytic pickling to pickling, pickling ability is improved, so that it is possible to remove the oxide film on the lower layer plating and ensure adhesion of the upper layer plating in the multilayer plating. In addition, a sulfuric acid cleaning device is used to remove sludge in the nickel line tank, and sulfuric acid contained in an electrolytic pickling liquid circulation tank is used as sulfuric acid used in the sulfuric acid cleaning device. Thereby, the sulfuric acid used for electrolytic pickling and the sulfuric acid used for sulfuric acid cleaning can be shared. And it is used repeatedly, without discarding sulfuric acid for every sulfuric acid washing. Furthermore, since the present invention uses an electrode in which platinum is plated on the surface of a titanium base material as an electrode used in electrolytic pickling, quality abnormality does not occur as in the case of using a lead electrode.

When a lead electrode was used as an electrode for electrolytic pickling, especially when the current density of electrolytic pickling was set to a high current density of 5.5 A / dm ² or more, the frequency of occurrence of lead adhesion abnormalities on the plated steel sheet increased. . It seems that the high current density promoted damage to the lead electrode. On the other hand, as a result of applying the present invention, even when the current density of the electrolytic pickling was a high current density, no quality abnormality caused by the electrode occurred. Therefore, the present invention exhibits a particularly high effect when the current density of electrolytic pickling is 5.5 A / dm ² or more.

  The present invention was applied to an electro nickel plating facility. Nickel plating was performed on the present invention example shown in FIGS. 1 and 2, the comparative example shown in FIG. 3, and the conventional example shown in FIG. The electric nickel plating equipment has two pickling line tanks 2 and three nickel line tanks 4, and has one rinsing tank 3 between the pickling line tank 2 and the nickel line tank 4. Yes. 1-4, the steel strip 1 advances from the right side to the left side, first pickling the steel strip surface with the pickling line tank 2, and then the excess acid adhering on the steel strip with the rinse tank 3 is removed. After removing, nickel electroplating is performed in the nickel line tank 4. In the present embodiment, the steel strip having a thickness of 0.15 mm and a plate width of 860 mm is passed at a line speed of 80 m / s.

  In the nickel line tank 4, the steel strip 1 is conveyed in the line tank by the energizing roll 5 and the sink roll 6, and energized through a rectifier and a bus bar (not shown) to a plurality of electrodes 7 installed so as to sandwich the steel strip 1. Plating is applied. The electrode 7 is a titanium mesh basket filled with nickel pellets of about 10 to 30 mmφ, and has an electrode length of 1.8 m and an electrode width of 1.1 m. A Watt bath is used as the plating bath, and the composition is nickel sulfate: 340 g / l, nickel chloride: 70 g / l, boric acid 45 g / l, and the bath temperature is 60 ° C.

In the pickling line tank 2, the conventional example shown in FIG. The pickling line tank 2 is filled with sulfuric acid, and the steel strip 1 is dipped in sulfuric acid for pickling. The comparative example shown in FIG. 3 and the example of the present invention shown in FIGS. In the electrolytic pickling, an electrode for electrolytic pickling is provided in the pickling line tank, and sulfuric acid stored in the electrolytic pickling liquid circulation tank 11 is circulated in the pickling line tank 2 in electrolytic pickling. In the comparative example, a lead electrode 8 was used as an electrode, and in the present invention example, an electrode 9 in which platinum was plated on one side using titanium as a base material was used. Place the platinized surface facing the steel strip. In the electrolytic pickling, Comparative Example, both the invention examples were tested the current density in two 2.8A / dm ² and 5.5A / dm ^2.

  The nickel line tank 4 is provided with a sulfuric acid cleaning device 10. When the sulfuric acid cleaning is performed, the nickel plating bath in the nickel line tank is removed, and instead, sulfuric acid is circulated in the nickel line tank using the sulfuric acid cleaning device 10. The sludge accumulated on the electrode 7 is dissolved in sulfuric acid, and the sludge is removed from the electrode 7. In the conventional example shown in FIG. 4, a sulfuric acid cleaning liquid circulation tank 12 dedicated to the sulfuric acid cleaning apparatus 10 is arranged, and sulfuric acid is circulated between the sulfuric acid cleaning liquid circulation tank 12 and the nickel line tank 4 via the sulfuric acid cleaning liquid circulation path 22. To do. In the comparative example shown in FIG. 3 and the example of the present invention shown in FIGS. 1 and 2, the electrolytic pickling liquid circulation tank 11 also serves as the sulfuric acid supply tank of the sulfuric acid cleaning device 10.

  Electro-nickel plating was performed under the conditions shown in Table 1, and evaluation was made on two points of plating adhesion and the occurrence of quality defects of lead adhesion. The plating adhesion was evaluated for each of the single layer nickel plating material and the multilayer nickel plating material. The results are shown in Table 1.

  In the conventional example, the pickling ability is weak because of the dipping pickling, and in the case of the multi-layer nickel plating material, plating adhesion failure such as peeling of the plating layer at the customer press occurs. Although the single-layer nickel plating material was good, plating peeling occurred very rarely depending on the operating conditions and customer press conditions.

Comparative Example No. 1 is electrolytic pickling using a lead electrode, but at a low current density of 2.8 A / dm ² , the oxide film of the lower plating layer cannot be sufficiently removed during the upper layer plating of the multi-layer plating material, resulting in plating peeling. Occur. In addition, although there is a slight frequency, quality defects due to lead adhesion also occur. Comparative Example No. When the current density is increased to 5.5 A / dm ^{2 as in 2} , the above-described plating peeling does not occur due to the strong pickling ability, but lead adhesion occurs as a result of the accelerated damage to the electrodes.

Invention Example No. 1, no. No. ² employs a titanium platinum electrode, and both current density: 2.8 and 5.5 A / dm ² are good in plating adhesion and quality defect in lead adhesion.

DESCRIPTION OF SYMBOLS 1 Steel strip 2 Pickling line tank 3 Rinse tank 4 Nickel line tank 5 Current supply roll 6 Sink roll 7 Electrode 8 Lead electrode 9 Electrode 10 Sulfuric acid washing apparatus 11 Electrolytic pickling liquid circulation tank 12 Sulfuric acid washing liquid circulation tank 13 Plating liquid circulation tank 21 Electrolytic pickling liquid circulation path 22 Sulfuric acid cleaning liquid circulation path 23 Plating liquid circulation path

Claims (1)

A steel strip that has a pickling line tank for pickling the surface of the steel strip and a nickel line tank for performing electro nickel plating on the surface of the steel strip, and then applying nickel electroplating to the surface of the steel strip after pickling the steel strip Electric nickel plating equipment,
It has a sulfuric acid cleaning device for removing sludge accumulated on electrodes arranged in the nickel line tank, and when performing sulfuric acid cleaning, sulfuric acid is circulated in the nickel line tank using the sulfuric acid cleaning device,
Electrolytic pickling is performed in the pickling line tank, and an electrode for electrolytic pickling is provided in the pickling line tank, and the sulfuric acid contained in the electrolytic pickling solution circulation tank is pickled in the pickling line tank. Circulates in,
Using sulfuric acid contained in the electrolytic pickling liquid circulation tank as sulfuric acid used in the sulfuric acid cleaning device,
An electric nickel plating facility for steel strip, wherein an electrode obtained by plating platinum on the surface of a titanium substrate is used as the electrode for the electrolytic pickling.

Images