[Technical Field of the Invention]
[OOOl]
The present invention relates to a Ni-plated steel sheet and a method for
producing a Ni-plated steel sheet.
Priority is claimed on Japanese Patent Application No. 2013-95785, filed on
April 30,2013, the content of which is incorporated herein by reference.
[Related Art]
[0002]
A steel sheet for a container, in which a chemical conversion treatment film
containing various elements such as zirconium (Zr), phosphorous (P), chromium (Cr),
titanium (Ti), manganese (Mn), and aluminum (Al) is formed on nickel (Ni) plating,
has been used as one of a metal material in manufacturing a metal container for
preservation of foods or beverages (for example, refer to Patent Document 1 to Patent
Document 3). The Ni-plated steel sheet including the chemical conversion treatment
film has excellent weldability due to the Ni-plating, and excellent adhesion with a film
or a coating material due to the chemical conversion treatment film.
[0003]
Patent Document 4 discloses a technology in which Ni strike plating is
performed, and Ni plating is formed through a cleaning process, thereby raising the
adhesion of the Ni-plating. The Ni-plated steel sheet is used as one of a frame
material in a color cathode-ray tube and can exhibit excellent weldability due to the Ni
plating and excellent plating adhesion due to the Ni strike plating.
[Prior Art Document]
[Patent Document]
I
iI [OOO~]
[Patent Document 11 Japanese Unexamined Patent Application, First
Publication No. H11-106952
[Patent Document 21 Japanese Unexamined Patent Application, First
Publication No. Hi 1-106954
[Patent Document 31 Japanese Unexamined Patent Application, First
Publication No. 2007-284789
[Patent Document 41 Japanese Unexamined Patent Application, First
Publication No. H6-330375
[Disclosure of the Invention]
[Problems to be Solved by the Invention]
[0005]
However, the Ni-plated steel sheets disclosed in Patent Document 1 to Patent
Document 3 are deficient in terms of corrosion resistance against highly corrosive
contents such as an acidic beverage. Accordingly, the Ni-plated steel sheet is mainly
used as a can material for weakly corrosive contents such as a body material for a
three-piece welded can that is a beverage can, and there is a problem in that the Niplated
steel sheet cannot he used as a can material for highly corrosive contents.
The Ni-plated steel sheet disclosed in Patent Document 4 uses Watts bath
which is commonly known for formation of the Ni-plated layer. In the Ni plating
using the Watts bath, even though the coating amount of Ni is increased, a dense film
is not formed but only surface unevenness become coarse, and thus the corrosion
resistance is not improved due to existence of a coating defect. In addition, Ni plating
formed by a Watts bath which is not containing chloride ions is dense, but the surface
unevenness is small, and thus weldability tends to decrease.
[O006]
As one of a method of improving the corrosion resistance of the Ni plating in
the steel sheet for a container, a method of increasing the amount of the chemical
conversion treatment film can be exemplified. However, a chemical conversion
treatment with a compound of Zr, P, Cr, Ti, Mn, Al, and the like is an insulating
chemical conversion treatment, and thus the weldability tends to decrease.
As described above, in the method of the related art, it is difficult to make the
corrosion resistance and the weldability compatible with each other.
In addition, in the steel sheet for a container, in the case of increasing the
amount of the Ni plating or the chemical conversion treatment Elm, there is a problem
in that the manufacturing cost increases.
[OOO7]
Accordingly, there is demand for a Ni-plated steel sheet having corrosion
resistance which can be used for highly corrosive contents and weldability during can
manufacturing, and which is highly cost effective.
[OOOS]
Accordingly, the present invention has been made in consideration of the
above-described problems, and an object thereof is to provide a Ni-plated steel sheet
which has excellent corrosion resistance and weldability and is highly cost effective,
and a method of producing a Ni-plated steel sheet.
[Means [or Solving the Problem]
[OOO9]
The present invention has been made to accomplish the above-described
object, and the gist thereof is as follows.
[OO 101
(1) According to a first aspect of the present invention, there is provided a Niplated
steel sheet including a steel sheet, a first Ni-plated layer which is formed at least
on a one-sided surface of the steel sheet and contains Ni, and a second Ni-plated layer
which is formed on the first Ni-plated layer and contains Ni. An average central-line
roughness Ra at an interface between the first Ni-plated layer and the second Ni-plated
layer is less than 0.1 pm, an average central-line roughness Ra of a surface of the
second Ni-plated layer is 0.1 pm to 100 pm, and a coating amount of Ni in an entirety
of the first Ni-plated layer and the second Ni-plated layer is 20 mg/m2 to 2500 mg/m2
per one-sided surface in terms of metal Ni.
(2) In the Ni-plated steel sheet according to (I), an amount of chlorine in the
first Ni-plated layer may be 0 ppm to 100 ppm.
(3) In the Ni-plated steel shect according to (1) or (2), a coating amount of Ni
in the first Ni-plated layer may be 15 mgh2 to 2000 mg/m2 per one-sided surface in
terms of metal Ni, and a coating amount ofNi in the second Ni-plated layer may be 5
mg/m2 to 500 mg/m2 pel one-sided surface in terms of metal Ni.
(4) The Ni-plated steel sheet according to any one of (1) to (3) may further
include a chemical conversion treatment film layer, which contains at least one of a
chromium oxide, a zirconium compound, a phosphate compound, a titanium oxide, an
i aluminum oxide, and a manganese oxide, on the second Ni-plated layer.
(5) In the Ni-plated steel sheet according to any one of (1) to (4), the coating
amount of Ni may be 400 mg/m2 to 1000 mg/m2 per one-sided surface in terms of
metal Ni.
(6) In the Ni-plated steel sheet according to any one of (1) to (5), the coating
amount of Ni in the first Ni-plated layer may be 300 mg/m2 to 800 mg/m2 per onesided
surface in terms of metal Ni, and the coating amount of Ni in the sccond Niplated
layer may be 100 mg/m2 to 200 mg/m2 per one-sided surface in terms of metal
Ni.
(7) In the Ni-plated steel sheet according to any one of (1) to (6), a surface of
the second Ni-plated layer may have unevenness in which a height difference in a
thickness direction of the steel sheet is 1 pm to 10 pm.
(8) According to a second aspect of the present invention, there is provided a
method for producing a Ni-plated steel sheet. The method includes a first plating
process of subjecting a steel sheet to an electrolysis treatment in a first Ni-plating bath
containing 5 g/L to 60 g/L of Ni ions, 20 g/L to 300 g/L of sulfate ions, 10 g/L to 60
g/L of borate ions, and less than 0.5 g/L of chloride ions to form a first Ni-plated layer
on the steel sheet, and a second plating process of subjecting the steel sheet, on which
the first Ni-plated layer is formed, to an electrolysis treatment in a second Ni-plating
I
I bath containing 5 g/L to 60 g/L of Ni ions, 20 g/L to 300 g/L of sulfate ions, 10 g/L to
60 g/L of borate ions, and 10 g/L to 60 g/L of chloride ions to form a second Ni-plated
layer on the first Ni-plated layer. A temperature of the first Ni-plating bath and a
temperature of the second Ni-plating bath are equal to or higher than 10°C and lower
than 9OoC, and in the first plating process and the second plating process, the
electrolysis treatment is performed at a current density of 1.0 A/dm2 to 100 A/dm2 for
:! an electrolysis treatment time of 0.2 seconds to 150 seconds.
(9) In the method for producing a Ni-plated steel sheet according to (8), a
rinsing process may not be provided between the first plating process and the second
plating process.
[Effects of the Invention]
[OOI 11
I
I According to the above-described aspects, it is possible to provide a Ni-plated
i steel sheet which has more excellent corrosion resistance and weldability and is highly
I cost effective by forming two kinds of Ni-plated layers on a surface of a steel sheet.
[Brief Description of the Drawings]
[0012]
FIG. 1A is a view schematically illustrating a Ni-plated steel sheet according
to an ~mhodimenot f the invention.
FIG. 1B is a view schematically illustrating the Ni-plated steel sheet according
,I to the embodiment.
!
1
FIG. 2A is a view schematically illustrating the Ni-plated steel sheet according
to the embodiment.
FIG. 2B is a view schematically illustrating the Ni-plated steel sheet according
to the embodiment.
FIG. 3 is a view schematically illustrating the Ni-plated steel sheet according
to the embodiment.
FIG. 4 is a flowchart illustrating an example of a flow of a method [or
j producing the Ni-plated steel sheet according to the embodiment.
FIG. 5A is a view illustrating the method for producing the Ni-plated steel
sheet according to the embodiment.
:I
1 FIG 5B is a view illustrating the method for producing the Ni-plated steel
sheet according to the embodiment.
i
[Embodiment of the Invention]
[OO 131
EIereinafter, a Ni-plated steel sheet and a method for producing a Ni-plated
steel sheet according to an embodiment of the invention will be described in detail with
reference to the accompanying drawings. In addition, in this specification and the
drawings, the same reference numeral is given to constituent elements having
substantially the same functional configuration, and redundant description thereof will
not be repeated.
[0014]
(With Respect to Configuration of Ni-Plated Steel Sheet)
First, a configuration of a Ni-plated steel sheet according to this embodiment
of the invention will be described in detail with reference to FIG. lA to FIG. 2B. FIG.
1A to FIG. 2B are views schematically illustrating a configuration of the Ni-plated steel
sheet according to this embodiment when viewed from a lateral side.
100 151
As shown in FIG. 1A and FIG. lB, a Ni-plated steel sheet 10 according to this
embodiment includes a steel sheet 101, a first Ni-plated layer 103, and a second Niplated
layer 105. The first Ni-plated layer 103 and the second Ni-plated layer 105
may be formed on a surface on only one side of the steel sheet 101 as shown in FIG.
1 A, or may be formed on the two surfaces of the steel sheet 101 which are opl)osite to
each other as shown in FIG. 1B.
100 161
(With Respect to Steel Sheet 101)
The steel sheet 101 is used as a base metal of the Ni-plated steel sheet 10
according to this embodiment. There is no particular limitation to the steel sheet 101
that is used in this embodiment, and typically, a known steel sheet, which is used as a
container material, can be used. There is also no particular limitation to a production
method or a material quality of the lcnown steel sheet as long as the known steel sheet
is produced by typical method through known processes such as casting, hot-rolling,
pickling, cold-rolling, annealing, and temper rolling. In addition, there is no
particular limitation to the surface roughness of the steel shcet 101 as long as the
surface roughness is in a range of surface roughness of a typical steel sheet that is
produced through the above-described processes.
[0017]
(With Respect to First Ni-Plated Layer 103)
As shown in PIG. 1A and FIG. 1B, the first Ni-plated layer 103 is formcd on a
surface of the steel sheet 101. The first Ni-plated layer 103 is an insoluble Ni-plated
layer which contains Ni (Ni is set as a main component). As a nickel electroplating
bath, a Watts bath, which contains Ni ions, sulfate ions, chloride ions, and borate ions
as a main component, is well known, but the first Ni-plated layer 103 is formed by
using a bath obtained by excluding the chloride ions from the Watts bath.
Accordingly, the first Ni-plated layer 103 becomes a Ni-piated layer that does not
contain chlorine (Cl). However, the chloride ions may be contained in the plating
bath in an amount of less than 0.5 g/L. In this case, the first Ni-plated layer contains
chlorine, but when thc anlount of chlorine in the first Ni-plated layer is 100 ppm or less.
there is no influence on the corrosion resistance and the weldability of the Ni-plated
steel sheet.
[00 1 81
The first Ni-plated layer 103, which is formed by using the Ni plating bath,
has a very dense surface and excellent corrosion resistance derived from the dense
surface. Surface roughness of the first Ni-plated layer 103 (in other words, roughness
at an interface between the first Ni-plated layer 103 and the second Ni-plated layer 105
to be described later) is less than 0.1 pm in terms of average central-line roughness Ra.
[0019]
In a case where the surface roughness Ra of the first Ni-plated layer 103 is 0.1
pm or greater, it is difficult to obtain corrosion resistance capable of withstanding
highly corrosive contents, and thus this range is not preferable. In addition, the
smaller a value of the surface roughness Ra of the first Ni-plated layer 103, the more
excellent the corrosion resistance, and thus the lower limit of the surface roughness Ra
is not particularly limited. However, a measurement limit in an apparatus of
measuring the average central-line roughness Ra is approximately 10 nm, and it is
difficult to measure surface roughness Ra that is lower than the measurement limit.
According to this, the lower limit of the surface roughness Ra of the first Ni-plated
layer 103 may be set to approximately 10 nm from the viewpoint of the measurement
limit.
[0020]
(With Respect to Second Ni-Plated Layer 105)
As shown in FIG. 1A and FIG. lB, the second Ni-plated layer 105 is formed
on the first Ni-plated layer 103. The second Ni-plated layer 105 is a soluble Ni-plated
layer that contains Ni (Ni is set as a main component). The second Ni-plated layer
105 is formed by using a so-called Watts bath that contains Ni ions, sulfate ions,
chloride ions, and borate ions as a main component. Accordingly, unlike the first Niplated
layer 103, the second Ni-plated layer 105 becomes a Ni-plated layer that
contains chlorine.
[0021]
As shown in FIG. 3, a surface of the second Ni-plated layer 105, which is
formed by using the Watts bath, has unevenness in which an average height h of each
unevenness is 0.1 p n ~to 100 p( that is, unevenness in which average central-line
roughness Ra is 0.1 pm to 100 pm). The unevenness becomes a starting point of
electrification during welding, and thus when the second Ni-plated layer 105 is
provided, it is possible to realize satisfactory weldability.
[0022]
In a case where the unevenness is less than 0.1 pm, the surface of the second
Ni-plated layer 105 becomes too flat, and thus the weldability decreases. Accordingl~:
this case is not preferable. In addition, in a case where the unevenness exceeds 100
pm, irregularity occurs in the external appearance, and thus this case is not preferable.
The unevenness of the surface of the second Ni-plated layer 105 (average height
difference in a thickness direction of the steel sheet) is more preferably 1 pm to 10 pm
[0023]
As described above, in the Ni-plated steel sheet 10 according to this
embodiment, the first Ni-plated layer 103 having a dense and flat surface is provided
on a surface side of the steel sheet 101, and thus excellent corrosion resistance is
realized, and excellent weldability is realized due to the second Ni-plated layer 105
having a surface which has large unevenness. According to this, even when surface
roughness of the steel sheet 101 is approximately 0.1 pm to 5 pm, an unevenliess
portion of the second Ni-plated layer 105 at a portion, in which the roughness of the
steel sheet 101 is the highest, exhibits satisfactory electrification properties during
welding, and thus it is possible to maintain weldability. In addition, even when the
surface roughness of the steel sheet 101 is approximately 0.1 pm to 5 pm, the first Niplated
layer 103, which is lormed as a lower layer of the second Ni-plated layer 105,
can maintain excellent corrosion resistance. Accordingly, in the Ni-plated steel sheet
10 according to this embodiment, it is possible to realize excellent corrosion resistance
and weldability without depending on the surface roughness of the steel sheet 101.
[0024]
(With Respect to Coating amount of Ni)
In the Ni-plated steel sheet 10 according to this embodiment, the coating
amount of Ni in the entirety of the first Ni-plated layer 103 and the second Ni-plated
layer 105 is 20 mg/m2 to 2500 mg/m2 per one-sided surface in terms of metal Ni. In a
case where the coating amount of Ni is less than 20 mg/m2, it is difkicult to realize the
corrosion resistance and the weldability as described above, and thus this case in not
preferable. In addition, in a case where the coating amount of Ni exceeds 2500
mg/mz, the corrosion resistance and the weldability as described above are saturated,
and thus this case is not preferable from the economical viewpoint.
Particularly, in a combination in which the coating amount of Ni in the first
Ni-plated layer is 15 mg/m2 to 2000 mg/m2 per one-sided surface in terms of metal Ni,
and the coating amount of Ni in the second Ni-plated layer is 5 mg/m2 to 500 mg/m2
per one-sided surface in terms of metal Ni, excellent corrosion resistance and
weldability can be realized.
Furthermore, when the coating amount of Ni in the entirety of the first Niplated
layer 103 and thc second Ni-plated layer 105 is set to 400 mg/m2 to 1000 mg/m2
per one-sided surface in terms of metal Ni, a more preferable result is obtained. In
this case, when combination is made in such a manner that the coating amount of Ni in
the first Ni-plated layer becomes 300 mg/m2 to 800 mg/m2, and the coating amount of
Ni in the second Ni-plated layer becomes 100 mg/m2 to 200 mg/m2, it is possible to
I
j
realize the Ni-plated steel sheet that is highly cost effective while maintaining the
corrosion resistance and weldability as described above.
[0025]
(With Respect to Chemical Conversion Treatment Film Layer 107)
For example, as shown in FIG. 2A and FIG. 2B, the Ni-plated steel sheet 10
according to this embodiment may further include a chemical conversion treatment
lilm layer 107 on the second Ni-plated layer 105. It is preferable that the chemical
conversion treatment film layer 107 contains at least one of a chromium oxide, a
zirconium compound, a phosphate compound, a titanium oxide, an aluminum oxide,
and a manganese oxide. There is no particular limitation to a method of forming the
chemical conversion treatment film layer 107, and it is possible to use known methods
such as an immersion treatment in a treatment solution, an electrolysis treatment using
a treatment solution, and a coating treatment using a treatment solution in accordance
with a compound that is used.
[0026]
In the following description, as a specific example of the chemical conversion
treatment film layer 107, a case of forming the chemical conversion treatment film
layer 107 by using a Zr compound, and a case of forming the chemical conversion
treatment film layer 107 by using a Cr oxide will be described briefly.
[0027]
For example, in the case of forming the chemical conversion treatnicnt film
layer 107 by using the Zr compound, an acidic solution, in which Zr ions and fluoride
ions are dissolved, is used. In the acidic solution, phosphate ions, a phenol resin, and
the like may be dissolved as necessary. It is possible to form the chemical conversion
treatment film layer 107 that contains the Zr compound (more specifically, a Zr oxide),
or the chemical conversion treatment film layer 107 that contains the Zr oxide and the
Zr phosphate compound through immersion of the steel sheet in the acidic solution, or
an cathode electrolysis treatment using the acidic solution.
[002S]
For example, in the case of forming the chemical conversion treatment film
layer 107 by using the Cr oxide, an aqueous solution, in which chromates such as a
sodium salt of chromic acid, a potassium salt, an ammonium salt, and the like of a
chromic acid are dissolved, is used. In the aqueous solution, sulfate ions or fluoride
ions may be dissolved as necessary. It is possible to form the chemical conversion
treatment film layer 107 that contains the Cr oxide through immersion of the steel
sheet in the aqueous solution, or a cathode electrolysis treatment using the aqueous
solution.
[0029]
When the chemical conversion treatment film layer 107 as described above is
further formed on the second Ni-plated layer 105, it is possible to further improve the
corrosion resistance of the Ni-plated steel sheet 10. In addition, in a case where a
film layer or a coating layer is further formed on the outermost surrace of the Ni-plated
steel sheet 10, when the chemical conversion treatment film layer 107 is formed, it is
possible to improve adhesion between the film or the coating material and the Niplated
steel sheet 10.
[0030]
In addition, a coating amount of the chemical conversion treatment film layer
I
I 107 is not particularly limited, and may be appropriately determined in accordance
with a compound that is used. For example, as a preferable coating amount, 1 mg/m2
to 150 mg/m2 can be exemplified.
I [0031]
A lmown treatment agent such as an anti-rust oil may be applied to an upper
layer of the chemical conversion treatment film layer 107 as necessary. In addition,
instead of the chemical conversion treatment film layer 107, a plated layer using a
metal such as Ti, Al, manganese (Mn), and tungsten (W) may be further formed on the
second Ni-plated layer 105.
[0032]
(With Respect to Method of Measuring Surface State of Ni-Plated Layer)
Next, a method of measuring a surface state of each of the Ni-plated layers
will be described.
The surface roughness of the first Ni-plated layer 103 can be measured by
using a known surhce roughness measuring device when the steel sheet passes through
the first Ni-plating bath that is used to form the first Ni-plated layer 103. Here, it is
necessary for the known surface roughness measuring device to have resolution of 0.1
pm or less with respect to the central-line roughness Ra.
[0033]
Even after the second Ni-plated layer 105 is formed, it is possible to measure
the surface roughness of the first Ni-plated layer 103 by a method to be described
below. That is, in the Ni-plated steel sheet 10 according to this embodiment, the first
Ni-plated layer 103 does not contain chlorine, and the second Ni-plated layer 105
contains chlorine. Accordingly, it is possible to specify an interface between the first
Ni-plated layer 103 and ihe second Ni-plated layer 105 by analyzing a chlorine
distribution on a cross-section of aNi-plated layer by using an analyzer such as a
cylindrical mirror analyzcr (CMA), an electron probe microanalyser (EPMA), and an
X-Ray fluorescence spectrometer (XRF). Thus, it is possible to measure the surface
roughness of the interface that is specified by using a known method.
[0034]
The surface state (unevenness) of the second Ni-plated layer 105 can be
measured by using a ltnown surface roughness measuring device. Here, it is
necessary for the known surface roughness measuring device to have resolution of 0.1
pm to 100 pm with respect to the central-line roughness Ra.
[0035]
(With Respect to Method for Measuring Coating amount ofNi)
Next, a method of measuring a coating amount of Ni in the first Ni-plated
layer 103 and the second Ni-plated layer 105 will be described.
The coating amount of Ni (amount in terms of metal Ni) can be measured, for
example, by a fluorescent X-ray method. In this case, a calibration curve illustrating
a correlation between the amount in terms of metal Ni and fluorescent X-ray intensity
is specified in advance by using a sample of the coating amount of Ni in which the
coating amount of Ni is already known, and the amount in terms of metal Ni can he
specified by using the calibration curve relatively.
[0036]
In addition, the method of measuring the coating amount of Ni (amount in
terms of metal Ni) is not limited to the above-described method, and other known
measuring methods are applicable.
[0037]
Hereinbefore, the configuration of the Ni-plated steel sheet 10 according to
this embodiment has been described in detail with reference to FIG. 1A to FIG. 3.
[0038]
(With Respect to Method for Producing Ni-Plated Steel Sheet)
Next, a method for producing the Ni-plated steel sheet 10 according to this
embodiment will be described in detail with reference to FIG. 4 to FIG. 5B. FIG. 4 is
a flowchart illustrating an example of a flow of the method for producing the Ni-platcd
steel sheet according to this embodiment, and FIG. 5A and FIG. 5B are views
illustrating the method for producing the Ni-plated steel sheet according to this
embodiment.
[0039]
First, an overall flow of the method for producing the Ni-plated steel sheet 10
will be described with reference to FIG. 4.
In the method for producing the Ni-plated steel sheet 10 according to this
embodiment, first, a pre-treatment is performed as necessary (step S 101). That is, oil,
a scale, and the like may be attached to a surface of the steel sheet 101 in dependence
on the steel sheet that is used as a base metal. Accordingly, a pre-treatment such as a
cleaning treatment of removing the oil or the scale on the steel sheet 101 is performed
prior to a Ni plating treatment to be described below.
[0040]
Then, the first Ni-plated layer 103 is formed on the surface of the steel sheet
through an electrolysis plating treatment using the first Ni-plating bath (step S103).
Continuously, the second plated layer 105 is formed on the first Ni-plated layer 103
through an electrolysis plating treatment using the second Ni-plating bath (step S105).
Details of components or each of the Ni-plating baths or details of the electrolysis
plating treatments will be described below in detail.
[0041]
After the two Ni-plated layers are formed on the steel sheet 101, the chemical
I
!
conversion treatment film layer 107 is formed on the second Ni-plated layer 105 by
I I
I using a known method (step S107).
Then, a post-treatment is performed with respect to the Ni-plated steel sheet
10, which is produced, as necessary (step S109). Although not particularly limited,
examples of the post-treatment include a treatment of applying an anti-rust oil on a
surface of the Ni-plated steel sheet 10.
100431
When performing the treatments in this order, the Ni-plated steel sheet 10
according to this embodiment is produced.
[0044]
In addition, in the above description, description has been given of the flow in
the case of forming the chemical conversion treatment film layer 107 on the sccond Niplated
layer 105, but in a case of not forming the chemical conversion treatment film
layer 107, it is needless to say that step S107 as described above may be omitted.
100451
(With Respect to Electrolysis Plating Treatment Using Ni-Plating Bath)
Next, an electrolysis plating treatment using two kinds of Ni-plating baths will
be described in detail with reference to FIG. 5A and FIG. 58.
100461
As described above, in the method for producing the Ni-plated steel sheet 10
according to this embodiment, two kinds of Ni-plating baths including the filst Niplating
bath that is used when forming the first Ni-plated layer 103, and the second Niplating
bath that is used when forming the second Ni-plated layer 105 are used. In a
production line for the Ni-plated steel sheet according to this embodiment, for example,
as shown in FIG. 5A, a first Ni-plating bath 201 is provided on an upstream side in a
steel sheet passing direction, and a second Ni-plating bath 203 is provided subsequent
the first Ni-plating bath 201.
[0047]
The first Ni-plating bath 201 is a Ni-plating bath that is used to form the first
Ni-plated layer 103, which is dense and has excellent corrosion resistance, on the
surface ofthe steel sheet 101 through insoluble Ni plating. The first Ni-plating bath
201 contains 5 g/L to 60 g/L of Ni ions, 20 g/L to 300 g/L of sulfate ions, 10 g/L to 60
g/L of borate ions, and unavoidable impurities. As is clear from the bath components,
chloride ions are not added to the first Ni-plating bath 201. In addition, a plating
solution is prepared by using a solvent such as ion exchanged water that does not
contain chloride ions so as to prevent the chloride ions from being mixed in the plating
bath 201. However, the chloride ions may be contained in the plating bath as long as
the chloride ions are contained in an amount of less than 0.5 g/L.
[0048]
In addition, electrodes 205, which are used for the electrolysis plating
treatment, are provided in the first Ni-plating bath 201 with the passing steel sheet
interposed therebetween. As each of the electrodes 205, for example, it is preferable
to use an insoluble electrode such as a titanium (Ti)-platinum (Pt) electrode, a lead
dioxide (PbOz) electrode, and a lead (Pb)-tin (Sn)-silver (Ag) electrode rather than a Ni
anode electrode.
The insoluble clectrode is excellent when considering that uniformity in Ni
plating is further improved in comparison to the Ni anode electrode. In the case of
using the Ni anode electrode for the electrolysis plating treatment, there is a concern
that a relatively large Ni lump will be separated in the bath during electrolysis, and
interposed between a sink roll and the steel sheet, thereby causing a pressed flaw.
Particularly, a dense and smooth surface is demanded in the formation of the first Niplated
layer, and thus this pressed flaw becomes a fatal error in terms of quality. On
the other hand, there is no concern relating to the pressed flaw in the insoluble
electrode, and Ni ions can be allowed to be present in the bath in an approximately
uniform manner, and thus uniform plating having excellent corrosion resistance tends
to be formed.
[0049]
For example, a bath temperature of the first Ni-plating bath 201 is set to be
equal to or higher than 10°C and lower than 90°C. In a case where the bath
temperature is lower than 1O0C, an efficiency of Ni adhesion deteriorates, and thus this
case is not preferable. In addition, in a case where the bath temperature is 90°C or
higher, unevenness in the Ni plating is not uniform, and thus this case is not preferable.
Thc bath temperature of the first Ni-plating bath 201 is more preferably equal to or
higher than 20°C and lower than 30°C.
[0050]
In addition, in the first Ni-plating bath 201, the electrolysis plating treatment
is performed under conditions of a current density of 1.0 Ndm2 to 100 ~/dm' and an
electrolysis treatment time of 0.2 seconds to 150 seconds.
In a case where the current density is less than 1.0 AJdm2, the efficiency of Ni
adhesion deteriorates, and thus this case is not preferable. On the other hand, in a
case where the current density exceeds 100 A/dm2, unevenness in the Ni plating is not
uniform, and thus this case is not preferable. The current density of the first Niplating
bath 201 is more preferably 5 A/dmz to 10 A/dm2.
In addition, in a case where the electrolysis treatment time is shorter than 0.2
~ seconds, it is difficult to obtain the coating amount of Ni that is necessary, and thus this
case is not preferable. On the other hand, in a case where the electrolysis treatment
I
! time exceeds 150 seconds, the coating amount of Ni becomes excessive, and thus this
I
I
I case is not preferable. The electrolysis treatment time in the first Ni-plating bath 201
I
is more preferably 0.3 seconds to 50 seconds, and still more preferably 0.5 seconds to 6
seconds.
[0051]
The second Ni-plating bath 203 is a Ni-plating bath that is used to form the
second Ni-plated layer 105, which has greater unevenness, on the surface of the first
Ni-plated layer 103 through soluble Ni plating. The second Ni-plating bath 203
contains 5 g/L to 60 g/L of Ni ions, 20 g/L to 300 glL of sulfate ions, 10 g/L to 60 g/L
of borate ions, 10 g/L to 60 g/L of chloride ions, and unavoidable impurities. When
the chloride ions are present m the Ni-plating bath at the above-described
concentration, the chloride ions are coordinated with the Ni ions which are present in
the bath to form a complex. When this complex is formed, chlorine is also mixed in a
plated layer that is formed, and thus the second Ni-plated layer 105 that is formed
becomes a plated layer that contains chlorine. In addition, when the complex is
formed, the chlorine ions, which are contained in the complex during electrolysis,
block uniform formation of the Ni plating. Accordingly, large unevenness which
brings an excellent weldability is formed in the second Ni-plated layer 105 that is
formed.
[0052]
In addition, electrodes 207, which are used for the electrolysis plating
treatment, are provided in the second Ni-plating bath 203 with the passing steel sheet
interposed therebetween. As is the case with the electrode 205 in the first Ni-plating
bath 201, an insoluble electrode such as a Ti-Pt electrode can be used as each of the
electrodes 207. However, in the case of using the insoluble electrode such as the Ti-
Pt electrode, a chlorine gas that is harmful to the human body is generated due to a
reaction of 2CI-+Cll+e- in the vicinity of the electrode, and thus it is necessary to
provide an exhaust facility [or exhaust of the chlorine gas. Accordingly, in the second
Ni-plating bath 203, it is preferable to use a Ni anode electrode as the electrode 207.
In the case of using the Ni anode electrode, Ni ions are eluted due to a reaction of
Ni-+N12'+2e'. In this case, the chlorine gas is not generated, and thus it is not
necessaly to provide the exhaust facility.
[0053]
For example, a bath temperature of the second Ni-plating bath 203 is set to be
equal to or higher than 10°C and lower than 90°C. In a case where the bath
temperature is lower than 1OUC, an efficiency of Ni adhesion deteriorates, and thus this
case is not preferable. In addition, in a case where the bath temperature is 90°C or
higher, unevenness in the Ni plating is not uniform, and thus this case is not preferable.
The bath temperature of the second Ni-plating bath 203 is more preferably equal to or
higher than 70°C and lower than 80°C.
[0054]
In addition, in the second Ni-plating bath 203, the electrolysis plating
treatment is performed under conditions of a current density of 1.0 Ndm2 to 100
Aldm2 and an electrolysis treatment time of 0.2 seconds to 150 seconds.
In a case where the current density is less than 1.0 A/dm2, the efficiency of Ni
adhesion deteriorates, and thus this case is not preferable. On the other hand, in a
case where the current density exceeds 100 A/dm2, unevenness in the Ni plating is not
uniform, and thus this case is not preferable. The current density of the second Niplating
bath 203 is more preferably 60 ~ / d mto 7~0 N dm2.
In addition, in a case where the electrolysis treatment time is shorter than 0.2
seconds, it is difficult to obtain the coating amount of Ni that is necessary, and thus this
case is not preferable. On the other hand, in a casc where the electrolysis treatment
time exceeds 150 seconds, the coating amount of Ni becomes excessive, and thus this
case is not preferable. The electrolysis treatment time in the second Ni-plating bath
203 is more preferably 0.3 seconds to 50 seconds, and still more preferably 0.5 seconds
to 6 seconds.
[0055]
As described above, in the method for producing the Ni-plated steel sheet
according to this embodiment, the second plating process using the second Ni-plating
bath 203 is continuously performed after the first plating process using the first Niplating
bath 201. The plating processes are performed in this order, and t h u ~th e
chloride ions, which are contained in the second Ni-plating bath 203, are not mixed
into the first Ni-plating bath 201.
In addition, as shown in FIG. 5A, a rinsing process of rinsing the surface of
the steel sheet may not be provided between the first plating process and the second
plating process. However, as shown in FIG. 5B, a rinsing bath 209 may be provided
between the first Ni-plating bath 201 and the second Ni-plating bath 203.
[0056]
FIG. 5A and FIG. 5B illustrate a case where the first Ni-plating bath 201 and
the second Ni-plating bath 203 have two-pass configurations. However, thc tmmber
of passes in the plating bath is not limited to that in the illustrated example, and may be
increased.
FIG. 5A and FIG. 5B illustrate a case where the first Ni-plating bath 201 and
the second Ni-plating bath 203 are provided as one tank respectively. However, both
the first Ni-plating bath 201 and the second Ni-plating bath 203 may be configured as a
plurality of sets.
Examples
LO0571
Hereinafter, the Ni-plated steel sheet and the method for producing the Niplated
steel sheet according to the invention will be described in detail with reference
to Examples and Comparative Example. In addition, the following Examples are
examples of the Ni-plated steel sheet and the method for producing the Ni-plated steel
sheet according to the present invention. The Ni-plated steel sheet and the method for
producing the Ni-plated steel sheet according to the present invention are not limited to
the following Examples.
[005S]
(Experiment Examples)
(1) Ni Plating Conditions
Ni-plated steel sheets were produced, by using two kinds of Ni Plating baths
shown in Table 1, and Table 3 to Table 5. In Table 1, and Table 3 to Table 5,
conditions described in a column called "first Ni-plating electrolysis conditions"
represent conditions relating to the first Ni-plating bath 201, and conditions described
in a column called "second Ni-plating electrolysis conditions" represent conditions
relating to the second Ni-plating bath 203.
[0059]
Here, in Experiment Examples shown in Table 1 and Table 2, an experiment
was performed with focus mainly given to characteristics of the Ni-plated steel sheet
that was produced, and in Experiment Examples shown in Table 3 and Table 4, an
"1
:! experiment was performed while further changing the Ni-plating bath that was used for
production of the Ni-plated steel sheet. In Experiment Examples shown in Table 5
I
and Table 6, an experiment was performed while changing the coating amount of Ni by
changing an electrification time in the electrolysis treatment
[0060]
Ni-plated steel sheets, which were produced under conditions shown in Table
1 to Table 6, were evaluated by the following evaluation method. Here, an amount of
metal Ni which is shown in Table 2 and Table 6 was measured with a measurement
device of coating amount by fluorescence X-ray, and the average central-line
roughness Ra at the interface between the first Ni-plated layer 103 and the second Niplated
layer 105, and the average central-line roughness Ra at the surface of the second
Ni-plated layer 105 were measured with a probe-type surface roughness measuring
device, respectively.
[0061]
In addition, with regard to the chemical conversion treatment film layer 107
formed on the second Ni-plated layer 105, as shown in Table 2, a film of a chromium
oxide or a film of a zirconium compound including ZrOz as a main component was
formed as the chemical conversion treatment film layer 107, and evaluation was
performed.
In a remark column in Table 1 to Table 6, a level corresponding to Examples
of the present invention are described as Example, and a level out of the range of the
present invention are described as Comparative Examples.
[0062]
In Table 3 and Table 4, measurement results of an amount of metal Ni and two
kinds of average central-line roughness Ra are not shown. However, even in
respective levels shown in Table 3 and Table 4, results relating to levels corresponding
to Examples were included in the range of the amount of metal Ni and the range of the
average central-line roughness which correspond to the Ni-plated steel sheet of the
present invention.
[0063]
(2) Evaluation Method
In Examples, evaluation was performed with respect to Ni-plated steel sheets
produced under conditions shown in Table 1, and Table 3 to Table 5 with focus given
to the corrosion resistance and the weldability.
[0064]
(Corrosion Resistance)
As a corrosion resistance test solution, 3% acetic acid was used. Each of the
Ni-plated steel sheets shown in Table I, and Table 3 to Table 5 was cut out in 435 mm
sizes, and was placed on an inlet of a heat-resistant bottle in which a corrosion
resistance test solution was put, and was fixed thereto. Then, a heat treatment was
performed at 121°C for 60 minutes. After the heat treatment, corrosion resistance
was evaluated using a ratio of a corroded area to an area in which the corrosion
resistance test solution came into contact with the Ni-plated steel sheet. More
specifically, grades from 1 point to 10 points were given in accordance with the ratio of
the corroded area to the area in which a test specimen and a test solution came into
contact with each other. In the corrosion resistance test, a steel sheet that received a
grade of 5 points or greater can be used as a steel sheet for a container.
100651
10 points: 100% to 90%
9 points: less than 90% and equal to or greater than 80%
8 points: less than 80% and equal to or greater than 70%
7 points: less than 70% and equal to or greater than 60%
6 points: less than 60% and equal to or greater than 50%
5 points: less than 50% and equal to or grcater than 40%
4 points: less than 40% and equal to or greater than 30%
3 points: less than 30% and equal to or greater than 20%
2 points: less than 20% and equal to or greater than 10%
1 point: less than 10% and equal to or greater than 0%.
[0066]
In a corrosion resistance evaluation item in Table 2 to Table 4, and Table 6, 10
points to 9 points is marked as "Very Good", 8 points to 7 points is marked as "Good",
6 points to 5 points is marked as "Fair", and 4 points or less is marked as "Poor".
[0067]
(Weldability)
With regard to the weldability, a welding machine for a beverage can, which
is manufactured by Soudronic AG, was used, and "Good or "Poor" as a grade of the
welding was determined in accordance with existence or non-existence of expulsion
which occurred at a welding site (lump of the steel sheet which extended from the
welding site by approximately 1 mm). A case where the expulsion did not occur was
determined as "Good, and a case where the expulsion occurs was determined as
"Bad".
[0068]
[Table 11
[0069]
[Table 21
[0070]
[Table 31
[0071]
[Table 41
[0072]
[Table 51
[0073]
[Table 61
100741
As is clear from Table 1 to Table 6, through the corrosion resistance test and
the welding test, it was proved that the steel sheets ofthe present invention have
excellent corrosion resistance and weldability.
[0075]
Hereinbefore, an appropriate embodiment of the present invention has been
described in detail with reference to the accompanying drawings, but the invention is
not limited to the example. It should be understood by those skilled in the art that
various modification examples or change examples can be made in the scope of the
contents described in claims, and thcse examples are also intended to be included in
the technical scope of the invention.
[Industrial Applicability]
100761
According to the invention, two kinds of Ni-plated layers are formeil on the
surface of the steel sheet, and thus it is possible to provide a Ni-plated steel sheet
which has more excellent corrosion resistance and weldability and is highly cost
effective.
[Brief Description ofihe Reference Symbols]
[0077]
10: Ni-PLATED STEEL SHEET
101: STEEL SHEET
103: FIRST Ni-PLATED LAYER
105: SECOND Ni-PLATED LAYER
107: CHEMICAL CONVERSION TREATMENT FILM LAYER
201: FIRST Ni-PLATING BATH
203: SECOND Ni-PLATING BATH
205,207: ELECTRODE
209: RINSING BATH

CLAIMS
1. A Ni-plated steel sheet, comprising:
a steel sheet;
a first Ni-plated layer which is formed at least on a one-sided surface ofthe
steel sheet and contains Ni; and
a second Ni-plated layer which is formed on the first Ni-plated layer and
contains Ni,
wherein an average central-line roughness Ra at an interface between the first
Ni-plated layer and the second Ni-plated layer is less than 0.1 pm,
an average central-line roughness Ra of a surface of the second Ni-plated
layer is 0.1 pm to 100 pm, and
a coating amount of Ni in an entirety of the first Ni-plated layer and the
second Ni-plated layer is 20 mg/m2 to 2500 mg/m2 per one-sided surface in terms of
metal Ni.
2. The Ni-plated steel sheet according to claim 1,
wherein an amount of chlorine in the first Ni-plated layer is 0 ppm to 100 ppm.
3. The Ni-plated steel sheet according to claim 1 or 2,
wherein a coating amount of Ni in the first Ni-plated layer is 15 mg/mZ to
2000 mg/m2 per one-sided surface in terms of metal Ni, and
a coating amount of Ni in the second Ni-plated layer is 5 mg/m2 to 500 mg/m2
per one-sided surface in terms of metal Ni.
4. The Ni-plated steel sheet according to any one of claims 1 to 3, further
-*-
3 i
comprising:
a chemical conversion treatment film layer, which contains at least one of a
chromium oxide, a zirconium compound, a phosphate compound, a titanium oxide, an
aluminum oxide, and a manganese oxide, on the second Ni-plated layer.
5. The Ni-plated steel sheet according to any onc of claims 1 to 4,
wherein the coating amount of Ni is 400 mg/m2 to 1000 mg/m2 per one-sided
surface in terms of metal Ni.
6. Tlie Ni-plated steel sheet according to any one of claims 1 to 5,
wherein the coating amount of Ni in the first Ni-plated layer is 300 mg/m2 to
800 mg/m2 per one-sided surface in terms of metal Ni, and
the coating amount oSNi in the second Ni-plated layer is 100 mg/m2 to 200
mg/m2 per one-sided surface in terms of metal Ni.
7. The Ni-plated steel sheet according to any one of claims 1 to 6,
wherein a surlace of the second Ni-plated layer has unevenness in which an
average height difference in a thiclmess direction of the steel sheet is 1 pm to 10 pm.
8. A method for producing a Ni-plated steel sheet, comprising:
a first plating process of subjecting a steel sheet to an electrolysis treatment in
a first Ni-plating bath containing 5 g/L to 60 g/L of Ni ions, 20 g/L to 300 g/L of
sulfate ions, 10 g/L to 60 g/L of borate ions, and less than 0.5 g/L of chloride ions to
form a first Ni-plated layer on the steel sheet; and
a second plating process of subjecting the steel sheet, on which the first NiI
plated layer is formed, to an electrolysis treatment in a second Ni-plating bath
containing 5 g/L to 60 g/L of Ni ions, 20 g/L to 300 g L of sulfate ions, 10 g/L to 60
g/L of borate ions, and 10 g/L to 60 g/L of chloride ions to fonn a second Ni-plated
layer on the first Ni-plated layer,
wherein a temperature of the first Ni-plating bath and a temperature of the
second Ni-plating bath are equal to or higher than 10°C and lower than 9OoC, and
in the first plating process and the second plating process, the electrolysis
treatment is performed at a current density of 1 .0 A/dm2 to 100 A/dmz for an
electrolysis treatment time of 0.2 seconds to 150 seconds.
9. The method for producing a Ni-plated steel sheet according to claim 8,
wherein a rinsing process is not provided between the first plating process and
the second plating process.