JP6319439B2 - Basket type anode - Google Patents

Description

  The present invention relates to a basket type anode used for electrolytic plating of a steel strip.

  In electrolytic plating in which the surface of a steel strip is continuously plated, a box-shaped basket type anode is widely used. In the basket type anode, the front surface facing the steel strip in the plating bath is constituted by a mesh member (lass) and accommodates the plating raw material grains. During electroplating, by energizing the main body of the basket type anode, the plating raw material grains in the basket type anode are electrolyzed and ionized, and the metal ions are guided to the surface of the steel strip to form plating. The main body and the net-like member of the basket type anode are made of pure Ti (pure titanium) because corrosion resistance is required.

  In recent years, there is a demand for plating large steel strips or plating with a large film thickness. In the operation of electroplating corresponding to this requirement, a large current needs to be supplied to the anode body. However, due to the supply of a large current to the anode body, the mesh member may be corroded and damaged. For example, in the case of electrolytic Ni plating in which the plating raw material grains are Ni grains and the plating bath is a Watt bath, part of the mesh member is corroded and a hole is opened in the mesh member as the operation proceeds.

  If the mesh member is significantly damaged, the possibility of the plating raw material particles leaking from the basket type anode is increased. If the plating raw material grains leak out, the amount of the plating raw material grains in the basket type anode rapidly decreases, and the amount of metal ions in the plating bath varies. Moreover, the plating raw material grains leaking into the plating bath may be caught in a roller that conveys the steel strip. Such a situation causes a deterioration in the quality of the plated steel sheet.

  Conventional techniques for dealing with this problem include the following. In Japanese Utility Model Publication No. 4-37907 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2011-89148 (Patent Document 2), the mesh member is inadvertently corroded by insulating the mesh member from the anode body. The technique which suppresses breakage | damage and suppresses the damage of a mesh-like member in connection with this is described.

  Specifically, Patent Document 1 describes a basket type anode having an improved structure for attaching a mesh member to an anode body. In the basket type anode described in this document, the mesh member is attached to the anode main body portion via an insulating material.

Patent Document 2 describes a basket type anode in which the structure of the mesh member itself is improved. In the basket type anode described in this document, an Al ₂ O ₃ (alumina) insulating film is formed on the surface of a mesh member, and this insulating film is sealed with a PTFE (polytetrafluoroethylene) film.

  However, even if the above-described conventional technology is applied, in reality, damage due to corrosion of the mesh member cannot be sufficiently suppressed. If it does so, in order to prevent the quality deterioration of a plated steel plate, the mesh member must be replaced | exchanged frequently, and the fall of the productivity of a plated steel plate is inevitable. From such a situation, it is strongly desired to improve the life of the mesh member.

Japanese National Fair No. 4-37907 Japanese Unexamined Patent Publication No. 2011-89148

The object of the present invention is to provide a basket type anode having the following characteristics:
To improve the life of the mesh member.

A basket-type anode according to an embodiment of the present invention is a basket-type anode that contains plating raw material grains in a plating bath and is used for electrolytic plating of a steel strip,
The said basket type anode is equipped with the mesh member made from Ti arrange | positioned facing the said steel strip, and the said mesh member contains a platinum group element.

  In the anode described above, the platinum group element content is preferably 0.01% to 0.15% by mass%.

  In the above anode, the mesh member may further contain one or more of Ni and rare earth elements. In this case, the Ni content is preferably 0.2% to 1.0% by mass%, and the rare earth element content is preferably 0.0005% to 0.020% by mass%. Further, in the above-described anode, as impure elements, by mass%, Fe: 0.3% or less, O: 0.35% or less, C: 0.18% or less, H: 0.015% or less, N: 0 0.03% or less, Al: 0.3% or less, Cr: 0.2% or less, Zr: 0.2% or less, Nb: 0.2% or less, Si: 0.02% or less, Sn: 0.2 % Or less, Mn: 0.01% or less, Co: 0.35% or less, and Cu: 0.1% or less may be contained in total of 0.6% or less.

  The anode can be used for electrolytic plating in which the plating raw material grains are Ni grains. Further, the anode can be used for electrolytic plating in which the plating bath is a watt bath.

The basket type anode of the present invention has the following remarkable effects:
The life of the mesh member can be improved.

FIG. 1 is a front view of a basket type anode. FIG. 2 is a longitudinal sectional view along the vertical direction of the basket type anode. FIG. 3 is a schematic diagram of a test apparatus used in the basic test for the corrosion resistance investigation.

  The inventors of the present invention have examined the cause of the net member made of pure titanium corroding and causing the breakage of the net member in the operation of electroplating for supplying a large current to the main body of the basket type anode, and the improvement measures. The examination was performed by taking electrolytic Ni plating, which is a typical example of electrolytic plating, as an example. In the case of electrolytic Ni plating, the plating raw material grains are Ni grains, and a watt bath is adopted as the plating bath.

[Standard configuration of basket-type anode]
FIG. 1 is a front view of a basket type anode. FIG. 2 is a longitudinal sectional view along the vertical direction of the basket type anode. In FIG. 2, white arrows indicate the flow of current supplied to the main body of the basket type anode.

  The basket type anode 1 is immersed in a plating bath 11, accommodates the plating raw material grains 10 in the plating bath 11, and is used for performing electrolytic plating on the steel strip 12. The basket-type anode 1 has a box shape with an open upper surface, and includes an anode main body 2 and a mesh member 3 constituting the front surface. The net member 3 is disposed in the plating bath 11 so as to face the steel strip 12. Plating raw material grains 10 are filled in the internal space of the basket type anode 1.

  The anode body 2 includes a back plate 2a, a pair of side plates 2b and 2c on the left and right sides, and a bottom plate 2d. A bus bar 2e for supplying current to the anode main body 2 is provided on the upper portion of the back plate 2a. The mesh member 3 is attached to the front surface side of the anode main body 2 having such a configuration. Specifically, a plurality of support columns 4 protrude forward from the back plate 2a. The mesh member 3 is addressed to the front end of each column 4, and the pressing plate 5 is addressed to the mesh member 3 at the position of each column 4. The holding plate 5 is fastened to each column 4 by bolts 6. As a result, the mesh member 3 is held on the front side of the anode main body 2 in a state of being sandwiched between each support column 4 and the pressing plate 5.

Strictly speaking, the net-like member 3 is configured by overlapping two metal nets 3a and 3b. The front side of the cloth bag 7 is sandwiched between the metal meshes 3a and 3b. The bag 7 allows the metal ions of the plating raw material grains 10 electrolyzed during electrolytic plating to pass through, while preventing the plating raw material grains 10 that have been reduced by electrolysis from leaking out from the mesh of the mesh member 3. The technique described in Patent Document 2 may be applied to the wire nets 3a and 3b here. That is, the metal nets 3a and 3b may have an Al ₂ O ₃ insulating film formed on the surface thereof, and the insulating film may be sealed with a PTFE film.

  Further, the mesh member 3 is usually attached to the anode body 2 by being divided into a plurality of stages in the vertical direction. In the basket type anode 1 shown in FIG. 1, a mode in which the mesh member 3 is divided into four stages is shown.

  During the electrolytic plating, a current is supplied to the main body 2 of the basket type anode 1 through the bus bar 2e of the back plate 2a. By this energization, the plating raw material grains 10 in the basket type anode 1 are electrolyzed and ionized, and the metal ions are guided to the surface of the steel strip 12 to form plating.

[Summary of causes of damage due to corrosion of mesh members and countermeasures]
In the conventional basket-type anode, the material of the mesh member is made of pure Ti, including the case where the technique described in Patent Document 2 is adopted. Using this conventional basket type anode, in the operation of electrolytic Ni plating for supplying a large current to the anode main body, the occurrence of breakage (perforation) of the mesh member was investigated. As a result, the following knowledge was obtained.

  The breakage of the mesh member is likely to occur at the upper part of the mesh member. This is considered to be due to a decrease in the pH of the plating bath, particularly at the upper part of the mesh member, as shown below.

As the operation of electrolytic Ni plating progresses, the Ni grains in the basket type anode are gradually consumed and become smaller, and the overall volume decreases. For this reason, particularly in the upper part of the mesh member, Ni particles become insufficient (does not exist), and a current flows directly from the anode body to the plating bath. In a region where current flows directly from the anode body to the plating bath, O ₂ gas is generated from the plating bath using the anode body as an electrode. The generation of this O ₂ gas is caused by the reaction of the following formula (1).
2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻ (1)

From the above equation (1), hydrogen ions are generated in the plating bath on the upper part of the mesh member as O ₂ gas is generated. For this reason, the pH of the plating bath is greatly lowered at the upper part of the mesh member.

However, when a Watt bath is employed in electrolytic Ni plating, the Watt bath contains boric acid for pH buffering. Even in this case, when the O ₂ gas according to the above formula (1) is generated in the plating bath on the upper part of the mesh member, the pH of the plating bath is largely lowered.

  When the pH drop of the plating bath is small, the net member made of pure Ti does not corrode and does not break. However, when the pH of the plating bath reaches an area where Ti depassivation occurs, the net member made of pure Ti corrodes and consequently breaks.

  From these facts, it is presumed that the cause of the damage due to corrosion at the upper part of the mesh member is that the pH of the plating bath reaches a region where Ti depassivation occurs. The upper limit of pH at which Ti depassivation occurs is about 1.

  Based on such knowledge, the present inventors have intensively studied a countermeasure that can prevent corrosion of the mesh member even when the pH of the plating bath is greatly lowered. As a result, the present inventors have found that it is effective to improve the chemical components of the net member itself based on Ti to obtain a Ti net member containing a platinum group element.

  When the platinum group element is contained in the Ti material, the platinum group element is either dissolved in Ti or a Ti-platinum group compound is produced. When such a platinum network element containing a platinum group element has a remarkable pH drop in the plating bath, the surface passive film dissolves and Ti dissolves, and the platinum group element also dissolves. put out. However, since the platinum group element dissolved together with Ti has a very noble redox potential, it immediately deposits on the surface of the mesh member.

  The platinum group element electrodeposited on the surface of the mesh member is a metal having a low hydrogen overvoltage, and lowers the hydrogen overvoltage. For this reason, the mesh member has a noble Ti corrosion potential and the surface is repassivated. This repassivation can terminate the dissolution of Ti.

[Fundamental tests on the cause of damage caused by corrosion of mesh members and countermeasures]
In order to verify the validity of the above countermeasures, the following basic tests were conducted. In the basic test, in the electroplating using a Watt bath as a plating bath, a situation was simulated in which a current flows directly from the main part of the basket type anode to the plating bath. At that time, the cathode (cathode) was regarded as a steel strip to be plated, the anode was regarded as a main body of the basket type anode, the test piece was regarded as a net member of the basket type anode, and the corrosion resistance of the test piece was investigated.

1. Preparation of test piece (1) Comparative material 1: Pure Ti
A plate material of pure Ti (2 types of JIS standards) having a thickness of 1 mm was prepared.

(2) Comparative material 2: Technology described in Patent Document 2 A plate material made of pure Ti (two types of JIS standards) having a thickness of 1 mm was obtained, and the surface of the plate material made of pure Ti was subjected to alumina spraying. Specifically, the Ar plasma spraying method is applied, and the spray material alumina (produced by Sanko Shokai Co., Ltd .: gray alumina Al ₂ O ₃ -2.5% TiO ₂ ) is heated using a plasma jet generated by a plasma spray gun. -By accelerating, alumina was melted or close to it and sprayed onto the surface of a pure Ti plate material to form an insulating film. Since this insulating film has pores, the insulating film was further sealed with a PTFE film.

(3) Test material of the present invention: Improvement of chemical composition based on Ti (titanium alloy)
(A) Raw materials As raw materials, industrial pure Ti sponge (a kind of JIS standard), 99.9% pure Pd (palladium) powder (manufactured by Kishida Chemical Co., Ltd.), 99.9% pure Ru (ruthenium) powder (Kishida Chemical Co., Ltd.), 99.9% -purified Y (yttrium) in shape (Kishida Chemical Co., Ltd.), massive rare earth elements, and massive electrolytic Co (cobalt) having a purity of 99.8% did. The massive rare earth elements were Mm (Misch metal: mixed rare earth), La (lanthanum), and Nd (neodymium), and those other than Mm having a purity of 99% were used. The chemical components of Mm were, by mass%, La: 28.6%, Ce (cerium): 48.8%, Pr (praseodymium): 6.4%, and Nd: 16.2%.

(B) Preparation of test piece Using an arc melting furnace in an argon atmosphere, various mixing ratios of the raw materials were changed, and square ingots having different chemical components were prepared. The size of each square ingot was 15 mm in thickness, 75 mm in width, and 95 mm in length. Here, when each square ingot is manufactured, first, in each case, five 80 g ingots are manufactured, and then all the ingots are combined and redissolved to prepare a square ingot having a thickness of 15 mm. The square ingot was redissolved for homogenization to produce a square ingot of the above size.

Each of the produced square ingots contained a trace amount of a platinum group element and, in some cases, further contained a rare earth element. Therefore, in order to reduce segregation of each element, homogenization heat treatment was performed. The conditions for this homogenization heat treatment were as follows.
Atmosphere: Vacuum (<10 ⁻³ torr (0.133 Pa))
・ Heating temperature: 1100 ° C
・ Heating time: 24 hours

The rectangular ingot subjected to the homogenizing heat treatment was rolled under the following conditions to finally form a plate material having a thickness of 1 mm.
・ Β-phase region hot rolling: Heating temperature is 1000 ° C., rolling 15 mm to 9 mm ・ α + β-phase region hot rolling: heating temperature is 875 ° C., rolling 9 mm to 1 mm

The plate material obtained by rolling was annealed to remove distortion. The annealing conditions were as follows.
Atmosphere: Vacuum (<10 ⁻³ torr (0.133 Pa))
・ Heating temperature: 680 ° C
・ Heating time: 7 hours

  The hot-rolled sheet thus obtained was machined to prepare a test piece. The size of each test piece of the test material of the present invention and the comparative materials 1 and 2 was 1 mm in thickness, 15 mm in width, and 15 mm in length. The surface of each of the test piece of the inventive example and the comparative material 1 was mirror-polished using a # 600 buff.

  The chemical components of the test materials 1 to 17 of the present invention and the comparative materials 1 and 2 were as shown in Table 1 below.

  The test pieces of the comparative materials 1 and 2 are pure Ti. Among them, the comparative material 2 employs the technique described in Patent Document 2, and an insulating film is formed on the surface, and this insulating film is sealed with a PTFE film.

  The test pieces 1 to 17 of the inventive examples are all Ti alloys containing a platinum group element. Among them, test materials 5, 6, 9, 11, 15, and 16 further contain Ni, and test materials 7 to 9, 14, and 17 further contain rare earth elements. The test material 13 contains two types of platinum group elements. The test material 12 has a platinum group element content below the desirable lower limit of the present invention. The test material 14 has a rare earth element content exceeding the desirable upper limit of the present invention. Test materials 15, 16, and 17 are examples containing Cr, Al, and Zr as impurity elements.

2. Contents of Basic Test (Corrosion Resistance Survey) (1) Test Method FIG. 3 is a schematic diagram of a test apparatus used for the basic test of the corrosion resistance survey. The test apparatus used for the basic test includes a plating bath 20 containing a plating solution (plating bath). The plating bath 20 is immersed in the constant temperature bath 21, and the temperature of the plating solution in the plating bath 20 can be kept constant.

  In the plating solution in the plating bath 20, a cathode (cathode) 22 assumed to be a steel strip to be plated was immersed, and an anode 23 assumed to be a main part of a basket type anode was immersed. As the cathode 22, a mild steel plate having a thickness of 1 mm and a width of 20 mm was used. The immersion length of the cathode 22 in the plating bath was 20 mm. As the anode 23, a plate material of pure Ti (two kinds of JIS standards) having a thickness of 1 mm and a width of 20 mm was used. The pure Ti plate as the anode 23 was cut out from the same material as that used for the comparative material 1, and the immersion length in the plating bath was set to 20 mm as with the cathode 22.

  Further, in the plating solution in the plating bath 20, the test piece 24 that is regarded as a mesh member of the basket type anode, that is, the above-described test pieces 1 to 11 of the present invention example and the test pieces of the comparative materials 1 and 2 were immersed. . Here, each test piece 24 was suspended between the anode 23 and the cathode 22 by a platinum wire 25 so that neither the anode 23 nor the cathode 22 was directly electrically connected.

A Watt bath was adopted as the plating bath (plating solution). Watts bath, nominal composition NiSO ₄ (nickel _{sulfate): 300-380g / L, NiCl 2} ( nickel chloride): 60-80g / L, and boric acid: Using those 35-55g / L. The amount of the watt bath was 60 cc.

In the basic test, a constant current of 3 A was continuously supplied from the DC power supply device to the anode 23 for 24 hours for each of the test pieces 1 to 11 of the present invention and the test pieces of the comparative materials 1 and 2. At that time, the current density was 37.5 A / dm ² and the watt bath temperature was 55 ° C. In addition, in order to reduce the influence of the water evaporation of a plating solution during a test, it supplied with electricity while the plating bath 20 was covered with parafilm from above.

(2) Evaluation method The pH of the plating solution was evaluated for each test on each test piece. Specifically, after energization for 24 hours, the pH of the plating solution was measured by a pH meter (Holiba pH meter D-70 series / ES-71 / OM-71).

Moreover, the corrosion rate was evaluated about each test piece. Specifically, assuming that the entire surface of each test piece is evenly corroded, based on the corrosion weight loss (weight loss) of each test piece and the specific gravity (4.51 g / cm ³ ) of the test piece by energization for 24 hours, From the equation (2), the corrosion thickness (mm) per 24 hours was calculated. In that case, the surface area of each test piece used the value computed from the thickness, the width | variety, and length of the test piece before a test.
Corrosion thickness per 24 hours = corrosion loss / (specific gravity × surface area) (2)

And the corrosion rate (mm / year) when 1 year passed was calculated | required from the following (3) formula from the corrosion thickness per 24 hours computed from the said (2) formula.
Corrosion rate = corrosion thickness per 24 hours × 365 days (3)

(3) Results of basic test The results are shown in Table 2 below.

  The results of the basic test shown in Table 2 indicate the following. In any of the tests, the pH of the plating solution was 4.6 before the start of the test, but was significantly lower than 1.0 after 24 hours of energization, and reached a region where Ti was passivated. From this, when a current flows directly from the anode 23 that looks like the main part of the basket type anode to the plating solution (plating bath), if the test piece that looks like the mesh member of the basket type anode is pure Ti, Was dissolved and it was found that the corrosion progressed.

  Since the test piece of Comparative Material 1 was pure Ti containing no platinum group element, significant weight loss and thinning were observed, and the corrosion rate reached 2.0 mm / year.

  In the test piece of the comparative material 2, since the surface is covered with the insulating film, the occurrence of corrosion is limited to the part where the insulating film is not completely formed, and the corrosion rate is reduced to about 1/5 of the comparative material 1. did. However, the corrosion rate reached 0.38 mm / year because it was still pure Ti containing no platinum group element.

  In each of the test pieces 1 to 17 of the inventive examples, since each of them is a Ti alloy containing a platinum group element, the corrosion rate was less than 0.1 mm / year, and remarkable corrosion resistance was recognized. In particular, in the test materials 1 to 5, 8, 13, 15, and 16 having a platinum group element content of 0.04% by mass or more, the corrosion rate is less than 0.01 mm / year, and the pH of the plating solution is 1.0. Almost complete corrosion resistance was observed despite being significantly below this value.

In addition, in the test pieces 6, 7, 9, 14 having a platinum group element content of 0.02% by mass or more and less than 0.04% by mass, the corrosion rate is about 0.02 mm / year. Met. Moreover, the corrosion rate was about 0.05 mm / year in the test piece of the test materials 10 and 11 of this invention example whose content of a platinum group element is less than 0.02 mass%. In the test piece of the test material 12 in which the platinum group element content was less than 0.01% by mass, the corrosion rate was 0.1 mm / year. The corrosion resistance of the test pieces of these test materials 6, 7, 9, 10, 11, 12, and 14 is not as high as the complete corrosion resistance of the test materials 1 to 5, 8, 13, 15, and 16, but the comparative material 1, Compared with 2, it was clearly improved.

  Here, the corrosion rate of the test material 12 was 0.1 mm / year, which was slightly higher than the standard (<0.1 mm / year) judged to be corrosion resistance. In the test material 14, the rare earth element content slightly exceeds the preferable upper limit. In this case, the corrosion rate was 0.1 mm / year, which was slightly higher than the standard (<0.1 mm / year) judged to be corrosion resistance. Although the test materials 15, 16, and 17 contain impurities, there was no effect on the corrosion resistance, and excellent corrosion resistance was exhibited in this test.

  As described above, from the results of the basic test, it is effective to use a Ti mesh member containing a platinum group element in order to prevent corrosion of the mesh member of the basket type anode and to improve the life of the mesh member. I understood it.

  The basket type anode of the present invention has been completed based on the above findings. Hereinafter, embodiments of the basket type anode of the present invention will be described.

[Basket Type Anode According to an Embodiment of the Present Invention]
In the basket type anode according to the present embodiment, the mesh member contains a platinum group element. This network member may further contain one or more of Ni and rare earth elements. If the mesh member contains a platinum group element, corrosion of the mesh member can be prevented, and the life of the mesh member can be improved.

  The platinum group element corresponds to six kinds of elements of Ru (ruthenium), Rh (rhodium), Pd (palladium), Os (osmium), Ir (iridium), and Pt (platinum). As long as it is selected from these six elements, there is no limitation on the type of platinum group element. That is, the platinum group element can contain one or more of six elements. However, since platinum group elements are rare and very expensive, it is preferable to select Ru or Pd among the six elements from the viewpoint of economy. This is because Ru and Pd have established recycling technologies and, among others, Ru can be stably obtained at a relatively low cost.

  The content of the platinum group element is not particularly limited. However, a large amount of platinum group element is not preferable from the viewpoint of economy. Therefore, the upper limit of the platinum group element content is preferably 0.15% by mass. A more preferable upper limit of the platinum group element content is 0.08% by mass.

  The lower limit of the platinum group element content is preferably 0.01% by mass in order to sufficiently improve the life of the mesh member. The lower limit of the platinum group element content is more preferably 0.02% by mass, and still more preferably 0.04% by mass.

  Here, if Ni or a rare earth element is contained in combination with the platinum group element, the content of the platinum group element can be reduced by a synergistic effect due to the inclusion of Ni or the rare earth element. For this reason, the inclusion of Ni or rare earth elements is advantageous from the viewpoint of economy.

  Ni, like the platinum group elements, has the effect of lowering the hydrogen overvoltage and making the corrosion potential of Ti noble. In order to obtain this effect, when Ni is contained for the purpose of reducing the content of the platinum group element, the lower limit of the Ni content is preferably 0.2% by mass. A more preferable lower limit of the Ni content is 0.4% by mass. On the other hand, a large amount of Ni brings about deterioration of workability and formability. For this reason, it is preferable that the upper limit of Ni content in the case of containing Ni is 1.0 mass%.

  Rare earth elements have the effect of accelerating the electrodeposition of platinum group elements on the surface of Ti materials containing platinum group elements when exposed to a corrosive environment within the range of content dissolved in Ti. . In order to obtain this effect, when a rare earth element is contained, the lower limit of the rare earth element content is preferably 0.0005 mass%. A more preferable lower limit of the rare earth element content is 0.001% by mass. On the other hand, when the rare earth element is contained excessively, the rare earth element alone may be precipitated, and the deposited rare earth element may be a factor of corrosion. The upper limit of the rare earth element content is considered to be the upper limit of the solid solution range of the rare earth element from the viewpoint of the mechanism, but there is a concern that segregation or the like occurs during dissolution. For this reason, the upper limit of the rare earth element content when the rare earth element is contained is preferably 0.020% by mass from the viewpoint of reliably obtaining a solid solution state.

  The rare earth element is a generic name of 17 elements obtained by adding Y and Sc to 15 elements of lanthanoid from La of atomic number 57 to Lu of 71 of the same, and contains one or more selected from these elements be able to. The rare earth element content means the total content of these elements.

  As described above, the basket-type anode mesh member (metal mesh) of the present embodiment is a titanium material and contains a platinum group element, and further contains at least one of Ni and rare earth elements. Impurity elements contained in addition to these elements include Fe, O, C, H, and N that enter from raw materials, melting electrodes, and the environment, and Al and Cr mixed when scrap is used as a raw material. , Zr, Nb, Si, Sn, Mn, Co, Cu and the like. There is no problem even if these impure elements are mixed as long as the effects of the present embodiment are not impaired. Specifically, in mass%, Fe: 0.3% or less, O: 0.35% or less, C: 0.18% or less, H: 0.015% or less, N: 0.03% or less, Al : 0.3% or less, Cr: 0.2% or less, Zr: 0.2% or less, Nb: 0.2% or less, Si: 0.02% or less, Sn: 0.2% or less, Mn: 0 0.01% or less, Co: 0.35% or less, and Cu: 0.1% or less, and there is no problem if the total of these is 0.6% or less.

  In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the basket type anode of this embodiment can be suitably used for electrolytic Ni plating in which the plating raw material grains are Ni grains and a Watt bath is adopted as the plating bath. There is no limitation for each type of grain and plating bath. The plating raw material grains to which the basket-type anode of this embodiment can be applied, that is, the type of plating, include Ni, gold, silver, copper, tin, zinc, and the like. Examples of the shape of the plating raw material grains include a spherical shape and a crown shape. In addition to the Watts bath, the types of plating baths to which the basket type anode of the present embodiment can be applied include a nickel sulfamate normal bath, a nickel sulfamate high speed bath, a strike bath (wood bath), and a black nickel plating bath. Etc.

  In order to confirm the effect of the present invention, an actual operation test was conducted in an electrolytic Ni plating line using the basket type anode shown in FIGS. 1 and 2 and employing a Watt bath as a plating bath.

[Test conditions]
In the test, five types of mesh members (strictly, metal mesh) were prepared. As shown in Table 3 below, three types of test materials 21, 22 and 23 having different chemical components were applied to the mesh member of the present invention. Two types of comparative materials 1 and 2 having the same chemical composition but different surface forms were applied to the net member of the comparative example.

  As shown in Table 3, all the mesh members of the test materials 21, 22 and 23 according to the present invention were Ti alloys containing a platinum group element. Among them, the mesh member of the test material 21 further contains Ni, and the mesh member of the test material 23 further contains Mm (Misch metal: mixed rare earth) which is a rare earth element. On the other hand, the net members of the comparative materials 21 and 22 which are comparative examples are both pure Ti (two types of JIS standards). Among them, the mesh member of the comparative material 22 was subjected to an alumina spraying treatment on the surface of the mesh in the same manner as the comparative material 2 in the basic test described above.

  Each of these five types of mesh members was attached as the uppermost mesh member of the basket type anode. Then, each basket type anode was immersed in the same Watt bath, and electrolytic Ni plating was continuously applied to the surface of the steel strip. This electrolytic Ni plating operation was continuously performed for 3 months.

The composition of the watt bath was nickel sulfate: about 340 g / L, nickel chloride: about 70 g / L, boric acid: about 45 g / L. The temperature of the Watt bath was about 55 ° C., and the pH of the Watt bath was 3.5 to 4.6. The anode body was continuously supplied with an electrolytic voltage of about 30 V at a steady-state current density of 34.5 A / dm ² . Each basket type anode was filled with crown type Ni grains and replenished periodically. At that time, just under the liquid level of the watt bath, with the consumption of Ni grains, often only the plating solution was present.

[Evaluation method]
After three months of continuous operation, the uppermost mesh member of each basket type anode was examined for corrosion and erosion. In this investigation, the uppermost mesh member after continuous operation was visually checked for the presence of melting damage.

  Furthermore, in this investigation, the net thickness of each net-like member was measured before and after continuous operation, and the degree of corrosion was evaluated from the reduction in thickness. The thickness of each mesh member was measured at three predetermined points A, B, and C. The measurement point A was a point 50 mm inside from the left end of the uppermost mesh member and 200 mm below the upper end. The measurement point B was a point at the center of the left and right of the uppermost mesh member and 200 mm below the upper end. The measurement point C was a point 50 mm inside from the right end of the uppermost mesh member and 200 mm below the upper end. These measurement points A, B, and C correspond to positions immediately below the liquid level of the Watt bath, and have conventionally been positions where breakage of the mesh member is likely to occur.

[result]
The results are shown in Table 4 below.

  In the mesh member of the comparative material 21, a part of the mesh was corroded and melted, and even if it remained, the mesh thickness was ½ or less. Further, in the mesh member of the comparative material 22, a reduction in the mesh thickness due to corrosion was observed at the portion where the formation of the insulating film was incomplete. On the other hand, in the mesh members of the test materials 21 to 23 which are examples of the present invention, no decrease in the mesh thickness due to corrosion was observed.

  From the above results, it was demonstrated that the basket type anode of this embodiment can improve the life of the mesh member.

  The basket type anode of the present invention can be effectively used for any electrolytic plating.

DESCRIPTION OF SYMBOLS 1 Basket type anode 2 Anode main-body part 2a Back surface plate 2b, 2c Side surface plate 2d Bottom surface plate 2e Bus bar 3 Net-like member 3a, 3b Metal mesh 4 Support column 5 Holding plate 6 Bolt 7 Bag 10 Plating raw material grain 11 Plating bath 12 Steel strip 20 Plating bath 21 Thermostatic bath 22 Cathode
23 Anode 24 Test piece 25 Platinum wire

Claims (7)

A basket-type anode that contains plating raw material grains in a plating bath and is used for electrolytic plating of a steel strip,
The basket-type anode includes a Ti alloy network member disposed to face the steel strip, the Ti alloy containing a platinum group element, and further containing one or more of Ni and a rare earth element. A basket type anode. The basket-type anode according to claim 1, wherein
The basket-type anode, wherein the platinum group element content in the Ti alloy is 0.01% to 0.08% by mass. The basket type anode according to claim 1 or 2,
The Ni content in the Ti alloy is 0.2% to 1.0% by mass%, and the rare earth element content is 0.0005% to 0.020% by mass%. Type anode. The basket type anode according to any one of claims 1 to 3,
In the Ti alloy mass%, Fe: 0.3% or less, O: 0.35% or less, C: 0.18% or less, H: 0.015% or less, N: 0.03% or less, Al : 0.3% or less, Cr: 0.2% or less, Zr: 0.2% or less, Nb: 0.2% or less, Si: 0.02% or less, Sn: 0.2% or less, Mn: 0 A basket type anode containing 0.01% or less, Co: 0.35% or less, and Cu: 0.1% or less in total of 0.6% or less. The basket type anode according to any one of claims 1 to 4,
A basket type anode, wherein the plating raw material grains are Ni grains. A basket type anode according to any one of claims 1 to 5,
A basket type anode, wherein the plating bath is a Watt bath.   The plating raw material grains are accommodated in the basket type anode according to any one of claims 1 to 6, the mesh member is opposed to the steel strip in a plating bath, and the energization to the main body portion of the basket type anode is performed. A method for producing a plated steel strip using a basket-type anode for plating a steel strip.

Images