JP2011089148A - Basket type anode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a basket type anode used for a watt bath and capable of reliably and stably preventing, for a long period of time, melting loss of a net member made of Ti opposed to a steel belt to be a plating object. <P>SOLUTION: In the basket type anode including an anode body 4 provided with an electricity supplying part 3, the net member 5 made of the Ti attached to an anode body 1 so as to be opposed to the steel belt 2 to be the plating object and a basket part 7 which is formed in a space enclosed by the anode body 1 and the net member 5 and in which Ni particles 6 are packed, the basket type anode 1 for performing electrolysis nickel plating to the steel belt 2 in the watt bath has an insulating coating film 11 formed by subjecting hole sealing treatment to the whole net member 5 using an insulating base material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a basket type anode for applying electrolytic Ni plating to a steel strip to be plated in a Watt bath.

A basket type anode used when electrolytic Ni plating is applied to a steel strip to be plated in a watt bath is widely known. For example, as shown in FIG. 5, this basket type anode includes an anode main body 24 having a power feeding portion 23, and a Ti mesh member (lass) attached to the anode main body 24 so as to face a steel strip to be plated. Net) 25 and a basket portion 27 for accommodating a plurality of Ni grains 26, which is a space surrounded by the anode body 24 and the net-like member 25, and the Ni grains 26 are filled in the basket portion 27. Then, power is supplied to the power supply unit 23, and each Ni grain 26 is energized through the anode body 24 to be electrolyzed and ionized.
It is known that when performing the electrolytic Ni plating using the watt bath using this type of basket type anode, when the power feeding portion 23 is energized, the mesh member 25 is melted by the electric corrosion caused by the current. . As a technique for preventing this melting damage, as described in Patent Document 1, a technique in which a mesh member is attached to an anode body via an insulating spacer such as plastic is known.

By the way, the operation of electrolytic Ni plating using a watt bath is within the range of potential and pH where Ni is ionized and electrolyzed, that is, pH 3.5 to 4.5, as shown in FIG. It is performed under the condition of the degree (range C in FIG. 6). On the other hand, Ti, which is the material of the mesh member, is in a stable range at the potential and pH of the above operating conditions (range D in FIG. 7) and exists in a stable state as TiO ₂ as shown in FIG. . Therefore, the technique described in the above cited document 1 can prevent the net member from being melted if it is normal.

  However, even when the technique described in the above cited document 1 is adopted, the actual situation is that the net-like member is still frequently melted, and this tendency is particularly remarkable on the upper side of the net-like member. If it is not possible to prevent the mesh member from being melted, it is necessary to frequently stop the operation for maintenance or replacement. In addition, Ni particles fall from the mesh member that has holes due to the melt damage, or the Ni particles that fall There was a high possibility of causing various troubles, such as being caught by a roller carrying the steel strip.

Japanese Utility Model Publication No. 4-37907

  The technical problem of the present invention is to provide a basket-type anode that can more reliably and stably prevent melting of a Ti mesh member over a long period of time.

In view of the above, as a result of intensive investigations to elucidate the cause of the erosion of the mesh member still occurring, the inventors have consumed Ni particles in the basket portion at the start of operation, and each Ni particle When it becomes smaller or deforms, a phenomenon called shelf hanging as shown in FIG. 5 (a) occurs due to the bumps between the Ni grains or the Ni grains and the net-like member, and the like in the basket portion. It was found that voids occurred in
In particular, on the upper side of the net-like member that is likely to cause melting damage, if the amount of Ni particles in the basket decreases due to consumption of Ni particles, the Ni particles move below the basket portion due to weight. It was found that there is a situation in which voids are likely to occur. Further, in recent years, instead of spherical pellets, Ni grains tend to use crown-shaped pellets that can be supplied at low cost and can be stably supplied. It has also been found that the shelf-hanging phenomenon is likely to occur even when Ni particles and the net-like member are stuck. In particular, it was found that the shelf hanging phenomenon due to the shape of the crown-shaped Ni particles is likely to occur on the upper side of the basket portion immediately after filling with new Ni particles.

  On the other hand, as indicated by the white arrow in FIG. 5 (a), a high current is applied to the anode body (especially the back side). It was also found that potential fluctuations occurred before reaching the mesh member. When the potential drops due to potential fluctuation as described above, as can be seen from the pH-potential diagram shown in FIG. 7, Ti, which is the material of the mesh member, is in the range from the stable region to the corroded region (E It was also found that the reticulated member is highly likely to be melted due to this ionization. Since the potential fluctuation in the anode occurs in the portion where the gap is generated in the basket portion, the potential fluctuation tends to occur particularly on the upper side of the mesh member where the Ni grain shelf-hanging phenomenon is likely to occur, and the potential decreases accordingly. It was found that Ti was ionized to cause melting damage (B portion in FIG. 5B) as shown in FIG.

As a result, the present inventors have found that by preventing the ionization of Ti, which is the material of the mesh member, due to potential fluctuations in the anode, it is possible to prevent melting of the mesh member. It came to be completed.
That is, in order to solve the above-mentioned problem, the basket type anode of the present invention includes an anode body provided with a power feeding portion, and a Ti mesh member attached to the anode body so as to face a steel strip to be plated. A basket portion formed in a space surrounded by the anode body and the mesh member and filled with Ni grains, and in the basket type anode in which electrolytic steel plating is applied to the steel strip in a watt bath. The entire member is provided with an insulating film that is formed of a material that does not melt within the pH range of the Watt bath and is sealed with an insulating material.

In the present invention, it is preferable that the insulating film of the mesh member is formed of Al ₂ O ₃ .
In this way, at pH 3.5 to 4.5, which is the operating condition of Ni plating by the watt bath, the insulating film is formed by Al ₂ O ₃ which does not enter the corroded area regardless of the electric potential. Even if a large potential drop occurs, the insulating film reliably and stably insulates and protects the mesh member by this Al ₂ O ₃ , so that melting damage can be prevented over a long period of time.

Moreover, in this invention, the insulating material of the sealing process with respect to the insulating film of the said mesh member can be a polytetrafluoroethylene.
As described above, by adopting polytetrafluoroethylene which is excellent in flowability and lubricity as an insulating material for the sealing treatment, it is easy to seal due to the flowability, and Ni particles are stuck by the lubricity. , And the shelf hanging phenomenon is less likely to occur, and the potential fluctuation itself can be suppressed as much as possible.

  According to the present invention, even if a potential fluctuation occurs in the anode, the insulating film formed of a material that does not melt within the pH range of the watt bath insulates and protects the entire Ti mesh member. It is possible to prevent the melting damage due to the long-term. Moreover, since it is possible to prevent electric corrosion of the mesh member starting from the pores on the surface of the insulating film, the mesh member can be reliably and stably insulated and protected.

It is a front view of the basket type anode concerning the present invention. It is the principal part expanded sectional view. It is a principal part expanded sectional view of the net-like member in the basket type anode concerning the present invention. A pH- electrograms Al ₂ O _3. (A) An enlarged cross-sectional view of the main part of a basket type anode showing a state in which a shelf-hanging phenomenon has occurred, (b) a basket type anode showing a state in which the damage has occurred. It is a principal part expanded sectional view. It is pH-potential diagram of Ni. It is a pH-potential diagram of Ti.

1 to 3 show an embodiment of a basket type anode according to the present invention. The basket type anode 1 of this embodiment is an electrolytic Ni plating on a steel strip 2 to be plated in a watt bath. The anode body 4 provided with the power feeding portion 3, the Ti mesh member 5 attached to the anode body 4 so as to face the steel strip 2, the anode body 4 and And a basket portion 7 formed in a space surrounded by the mesh member 5 and filled with Ni particles 6 to be electrolyzed.
In FIG. 2, white arrows indicate the current flow for electrolyzing Ni grains.

The anode body 4 includes a Ti back plate 4a, Ti side plates 4b, 4c extending forward on the left and right sides of the back plate 4a, and extending from the lower end portion of the back plate 4a to the front side and both left and right ends. Is provided with a Ti bottom plate 4d connected to the lower end portions of the left and right side plates, and further has a bus bar 4e in which the power feeding portion 3 is disposed at the upper end portion of the back plate 4a.
On the other hand, the mesh member 5 is attached to the front side of the anode body 4 which is positioned opposite to the steel strip 2 to be plated. In this embodiment, the mesh member 5 is made of Ti having excellent strength. The lath nets 5a and 5b are stacked. In addition, between these two lath nets, that is, between the front lath net 5a and the rear lath net 5b, an anode made of cloth that prevents the outflow of Ni particles that are reduced due to wear and allows ions to pass therethrough. The front side of the back 8 is sandwiched.
The space surrounded by the back plate 4a, the left and right side plates 4b, 4c and the bottom plate 4d of the anode body 4 and the mesh member 5 has the basket portion 7 having an upper opening for filling Ni particles. It has become.

  As shown in FIG. 2, the mesh member 5 is attached to the anode body 4 by attaching a plurality of columnar ribs 9 whose base end side is attached to the back plate 4a and rises perpendicularly from the back plate 4a to the front side. This is performed by a long plate-like pressing member 10 that is locked to the tip end side of the rib 9. That is, the presser member 10 is locked to the front end side of the rib 9 through the hole of the net member 5 from the front side (the surface facing the steel strip 2) of the net member 5 abutted with the front end side of each rib 9. As a result, the mesh member 5 is held on the front side of the anode body 4 in a state where the mesh member 5 is sandwiched between the tip side of each rib 9 and the pressing member 10.

By the way, as shown in FIG. 3, the mesh member 5 and, more specifically, the lath meshes 5a and 5b on the front and rear surfaces, as a whole are provided with an insulating film 11 that is sealed with an insulating material. .
Specifically, the insulating film 11 is formed by spraying Al ₂ O ₃ (alumina) as an insulating material on the entire surface of the mesh member 5. Further, a sealing film 12 made of polytetrafluoroethylene (Teflon (registered trademark)), which is also an insulating material, is formed and sealed.
Here, the reason why Al ₂ O ₃ was used as the material for the insulating film 11 is that, as shown in FIG. 4, Al ₂ O ₃ is used at a pH of 3.5 to 4.5, which is the operating condition of Ni plating using a watt bath. This is because it is a material that does not melt regardless of the potential, that is, it does not enter the corrosion region (region that ionizes to become Al ³⁺ ) regardless of the potential (see the range of A in FIG. 4). Therefore, not only the potential during normal operation in which Ni is ionized, but also a large potential fluctuation in the anode 1, especially even if a significant decrease in potential such that Ti is ionized occurs, it does not ionize and does not melt, The insulating film 11 made of Al ₂ O ₃ can reliably and stably insulate and protect the Ti mesh member 5.
In addition, Al ₂ O ₃ has good adhesion to Ti, which is a material for the net-like member, and does not require special ground treatment, and thus has an advantage that an insulating film can be easily formed.

On the other hand, the reason why polytetrafluoroethylene is used as an insulating material for the sealing treatment of the insulating film 11 of the mesh member 5 is that polytetrafluoroethylene has excellent flowability and lubricity. .
That is, as shown in FIG. 5, there are always pores 11a on the sprayed surface, but the polytetrafluoroethylene is formed on the insulating coating 11 by the spraying of Al ₂ O ₃ due to its excellent flowability. The generated pores 11a are sufficiently filled and can be surely sealed, so that the electric erosion of the Ti mesh member 5 starting from the pores 11a can be prevented more stably and reliably. be able to.
Furthermore, polytetrafluoroethylene suppresses the bumps between the Ni particles 6 and the mesh member 5 due to its excellent lubricity, and also reduces the bumps between the Ni particles, thereby suspending the Ni particles 6 from the shelf. There is an advantage that the phenomenon can be made difficult to occur, whereby the potential fluctuation itself can be suppressed as much as possible, and the burden on the insulating film 11 due to the potential fluctuation can be reduced.

  The Ni particles 6 filled in the basket portion 7 are so-called crown-shaped pellets formed in a substantially hemispherical crown shape, and the Ni particles 6 already placed in the basket portion 7 are used. When the amount is reduced due to wear, the basket portion 7 is sequentially replenished from the upper opening.

The basket-type anode 1 having the above-described configuration is filled with Ni grains 6 from the upper opening in the basket portion 7 and then fed to the power feeding section 3 in the watt bath, and the Ni grains 6 are electrolyzed and ionized. Ni plating is applied to the steel strip 2 to be plated.
At this time, not only when the anode 1 is at a normal potential during operation, but also when the Ni particles 6 are suspended in the basket portion 7 and the potential fluctuation occurs in the anode 1, a Ti mesh An insulating film 11 formed on the entire member 5 insulates and protects the mesh member 5. Thereby, the melting loss resulting from potential fluctuation can be prevented over a long period of time. In addition, since the erosion of the mesh member 5 starting from pores on the surface of the insulating film 11 can be prevented, the mesh member 5 can be reliably and stably insulated and protected.

In particular, the insulating film 11, by the inside pH of the Watts bath formed by thermal spraying of Al ₂ O ₃ which do not ionize regardless potential, the insulating film 11 by the Al ₂ O ₃ even when occurred potential displacement soluble Since the mesh member 5 is reliably insulated without damaging it, it is possible to prevent the mesh member 5 from being melted more stably and for a long time regardless of potential fluctuations.
Furthermore, by adopting polytetrafluoroethylene as an insulating material for the sealing treatment of the insulating film 11, the sealing treatment utilizing the excellent flowability can be performed reliably, and the lubricity Since the shelf hanging phenomenon can be reduced as much as possible by suppressing the bumps between the Ni grains 6 and the mesh member 5 and between the Ni grains, the shelf life of the mesh member 5 can be extended more stably. Is possible.

In the above embodiment, the insulating film is formed by thermal spraying of Al ₂ O ₃ , but any means can be used as a means for forming the insulating film.
In addition, the material for forming the insulating film may be other than Al ₂ O ₃ , but it is not ionized at the potential of normal operation and the pH of the watt bath (pH 3.5 to 4.5), and it is temporarily potential. It must be non-ionized at the pH of the Watt bath even if fluctuations occur.

In order to confirm the effect of the present invention, the basket-type anode having the configuration according to the above-described embodiment of the present invention, that is, the entire mesh member is formed with an insulating film that is sealed with an insulating material. A conventional basket type anode not depending on the configuration of the present invention, that is, a mesh member in which an insulating film is not formed, was compared in terms of the state of melting of the mesh member. That is, the basket type anode according to the present invention and the related art was immersed in a watt bath having a pH of 3.5 to 4.5, and the steel strip to be plated was plated.
The basket type anode according to the present invention has an insulating film formed by Al ₂ O ₃ thermal spraying and is sealed with polytetrafluoroethylene as in the above embodiment. .
The composition of the Watt bath into which the present invention and the conventional basket type anode are immersed is about 340 g / l nickel sulfate, about 70 g / l nickel chloride, about 45 g / l boric acid, and the bath temperature is about 50 ° C. . In addition, an electrolytic voltage of about 30 V was continuously applied to each anode at a current density of 0.5 to 34.6 A / dm ² basically. Further, the Ni grains filled in the basket portion of each anode were crown-shaped, and both were regularly replenished.

As a result, the conventional basket type anode was damaged by the mesh member in about 2 to 3 months, whereas the basket type anode of the present invention was damaged by the mesh member even after 15 months. There wasn't.
Thereby, it was demonstrated that the basket-type anode according to the configuration of the present invention can prevent the net member from being melted for a long period of time as compared with the conventional one.

1: Basket type anode 2: Steel strip 3: Power feeding part 4: Anode body 5: Mesh member 6: Ni grain 7: Basket part 11: Insulating film

Claims (3)

An anode body provided with a power feeding portion, a Ti mesh member attached to the anode body so as to face a steel strip to be plated, and a space surrounded by the anode body and the mesh member A basket-type anode comprising a basket portion filled with Ni grains, and applying electrolytic Ni plating to the steel strip in a watt bath,
A basket-type anode, characterized in that the entire mesh member is provided with an insulating film formed of a material that does not melt within the pH range of the Watt bath and sealed with an insulating material. The basket type anode according to claim 1, wherein the insulating film of the mesh member is formed of Al ₂ O ₃ . The basket type anode according to claim 1 or 2, wherein the insulating material for the sealing treatment for the insulating film of the mesh member is polytetrafluoroethylene.

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