U.S. patent application number 11/664095 was filed with the patent office on 2008-05-08 for molten salt bath, deposit obtained using the molten salt bath, method of manufacturing metal product, and metal product.
Invention is credited to Shinji Inazawa, Hironori Nakajima, Koji Nitta, Toshiyuki Nohira, Kazunori Okada.
Application Number | 20080105553 11/664095 |
Document ID | / |
Family ID | 36142554 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080105553 |
Kind Code |
A1 |
Nitta; Koji ; et
al. |
May 8, 2008 |
Molten Salt Bath, Deposit Obtained Using The Molten Salt Bath,
Method Of Manufacturing Metal Product, And Metal Product
Abstract
A molten salt bath includes at least one kind selected from the
group consisting of chlorine, bromine, and iodine, zinc, at least
two kinds of alkali metals; and fluorine. Here, the molten salt
bath may include oxygen. Furthermore, the molten salt bath may
include at least one kind selected from the group consisting of
tungsten, chromium, molybdenum, tantalum, titanium, zirconium,
vanadium, hafnium, and niobium. Additionally provided are a deposit
obtained using the aforementioned molten salt bath, a method of
manufacturing a metal product using the aforementioned molten salt
bath, and a metal product.
Inventors: |
Nitta; Koji; (Osaka, JP)
; Inazawa; Shinji; (Osaka, JP) ; Okada;
Kazunori; (Osaka, JP) ; Nohira; Toshiyuki;
(Kyoto, JP) ; Nakajima; Hironori; (Kyoto,
JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Family ID: |
36142554 |
Appl. No.: |
11/664095 |
Filed: |
September 22, 2005 |
PCT Filed: |
September 22, 2005 |
PCT NO: |
PCT/JP05/17510 |
371 Date: |
March 29, 2007 |
Current U.S.
Class: |
205/50 ; 205/136;
205/80 |
Current CPC
Class: |
C25D 3/66 20130101; C25D
5/022 20130101 |
Class at
Publication: |
205/50 ; 205/136;
205/80 |
International
Class: |
C25D 5/02 20060101
C25D005/02; C25D 5/00 20060101 C25D005/00; C25D 7/00 20060101
C25D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2004 |
JP |
2004-290519 |
Claims
1. A molten salt bath including at least one kind selected from the
group consisting of chlorine, bromine and iodine, zinc, at least
two kinds of alkali metals, and fluorine.
2. The molten salt bath according to claim 1, characterized by
including oxygen.
3. The molten salt bath according to claim 1, characterized by
including at least one kind selected from the group consisting of
tungsten, chromium, molybdenum, tantalum, titanium, zirconium,
vanadium, hafnium, and niobium.
4. The molten salt bath according to claim 1, characterized by
being made of at least two kinds selected from the group consisting
of sodium, potassium and cesium as said alkali metals, at least one
kind of chlorine and bromine, zinc, and fluorine.
5. The molten salt bath according to claim 1, characterized in that
a content of said zinc is at least 14 atomic % and at most 30
atomic % of said molten salt bath as a whole.
6. The molten salt bath according to claim 1, characterized in that
a content of said zinc is at least 17 atomic % and at most 25
atomic % of said molten salt bath as a whole.
7. The molten salt bath according to claim 1, characterized in that
a content of said fluorine is at least 0.1 atomic % and at most 20
atomic % of said molten salt bath as a whole.
8. A deposit obtained using the molten salt bath according to claim
1.
9. The deposit according to claim 8, characterized in that the
deposit is formed in a state in which said molten salt bath
includes at least 0.01 atomic % of oxygen.
10. The deposit according to claim 8, characterized in that
arithmetic mean roughness Ra (JIS B0601-1994) of a surface of said
deposit is at most 3 .mu.m.
11. The deposit according to claim 8, characterized in that a
relative density of said deposit is at least 85%.
12. A method of manufacturing a metal product comprising the steps
of: forming a resist pattern on a conductive substrate to expose a
part of said conductive substrate; immersing the conductive
substrate having said resist pattern formed thereon in the molten
salt bath according to claim 1; and depositing a metal from said
molten salt bath on the exposed part of said conductive
substrate.
13. The method of manufacturing a metal product according to claim
12, characterized in that a temperature of said molten salt bath is
at most 250.degree. C.
14. A metal product manufactured using the method of manufacturing
a metal product according to claim 13.
Description
TECHNICAL FIELD
[0001] The present invention relates to a molten salt bath, a
deposit obtained using this molten salt bath, a method of
manufacturing a metal product, and a metal product.
BACKGROUND ART
[0002] Conventionally, when a metal product is manufactured by
electroforming or a substrate is coated, a technique of depositing
a metal in a bath by electrolysis is used. Specifically, in recent
years, in various fields of information communication, medical
care, biotechnology, automobiles and the like, MEMS (Micro Electro
Mechanical Systems) receive attention which allows production of
fine metal products that are compact in size, have high performance
and are energy-efficient. It is contemplated to manufacture a fine
metal product applicable to MEMS or to coat the surface of the fine
metal product using the technique of deposing a metal by
electrolysis.
[0003] On the other hand, since metals (refractory metals) such as
tungsten and molybdenum of the fourth to sixth period of Group
IVA-Group VIA of the periodic table are heat-resistant and
corrosion-resistant, these metals can be used for the above-noted
fine metal product to manufacture a fine metal product with high
heat-resistance and durability.
[0004] Non-Patent Document 1: P. M. COPHAM, D. J. FRAY, "Selecting
an optimum electrolyte for zinc chloride electrolysis", JOURNAL OF
APPLIED ELECTROCHEMISTRY 21 (1991), p. 158-165
[0005] Non-Patent Document 2: M. Masuda, H. Takenishi, and A.
Katagiri, "Electrodeposition of Tungsten and Related Voltammetric
Study in a Basic ZnCl.sub.2--NaCl (40-60 mol %) Melt", Journal of
the Electrochemical Society, 148(1), 2001, p. C59-C64
[0006] Non-Patent Document 3: Akira Katagiri, "Electrodeposition of
Tungsten in ZnCl.sub.2--NaCl and ZnBr.sub.2--NaBr Melts", Molten
Salts and High-temperature Chemistry, Vol. 37, No. 1, 1994, p.
23-38
[0007] Non-Patent Document 4: Nikonowa I. N., Pawlenko S. P.,
Bergman A. G., "Polytherm of the Ternary System
NaCl--KCl--ZnCl.sub.2", Bull. acad. sci. U.R.S.S., Classe sci.
chim. (1941), p. 391-400
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0008] However, although metals such as nickel and copper can be
deposited by electrolysis after being dissolved in water,
refractory metals cannot be deposited by electrolysis using aqueous
solution.
[0009] Then, for example, a molten salt bath formed by melting, for
example, a zinc chloride or bromide, a sodium chloride or bromide,
and a refractory metal compound is used to deposit a refractory
metal by electrolysis. However, the purity, density and denseness
of the resulting deposit is low, and in addition, the surface of
the deposit is coarse.
[0010] An object of the present invention is to provide a molten
salt bath allowing production of a refractory metal deposit with
high purity, high density and high denseness and having a smooth
surface, a deposit obtained using the molten salt bath, a method of
manufacturing a metal product, and a metal product.
Means for Solving the Problems
[0011] The present invention provides a molten salt bath including
at least one kind selected from the group consisting of chlorine,
bromine and iodine, zinc, at least two kinds of alkali metals, and
fluorine.
[0012] Here, the molten salt bath of the present invention may
include oxygen.
[0013] The molten salt bath of the present invention may include at
least one kind selected from the group consisting of tungsten,
chromium, molybdenum, tantalum, titanium, zirconium, vanadium,
hafnium, and niobium.
[0014] The molten salt bath of the present invention may be made of
at least two kinds selected from the group consisting of sodium,
potassium and cesium as the alkali metals, at least one kind of
chlorine and bromine, zinc, and fluorine.
[0015] Preferably, in the molten salt bath of the present
invention, a zinc content is at least 14 atomic % and at most 30
atomic % of the molten salt bath as a whole.
[0016] Preferably, in the molten salt bath of the present
invention, a zinc content is at least 17 atomic % and at most 25
atomic % of the molten salt bath as a whole.
[0017] Preferably, in the molten salt bath of the present
invention, a fluorine content is at least 0.1 atomic % and at most
20 atomic % of the molten salt bath as a whole.
[0018] The present invention also provides a deposit obtained using
any of the above-noted molten salt bath. Here, the deposit of the
present invention is preferably formed in a state in which the
molten salt bath includes at least 0.01 atomic % of oxygen.
[0019] Preferably, arithmetic mean roughness Ra (JIS B0601-1994) of
a surface of the deposit of the present invention is at most 3
.mu.m.
[0020] Preferably, a relative density of the deposit of the present
invention is at least 85%.
[0021] The present invention additionally provides a method of
manufacturing a metal product including the steps of: forming a
resist pattern on a conductive substrate to expose a part of the
conductive substrate; immersing the conductive substrate having the
resist pattern formed thereon in any of the above-noted molten salt
bath; and depositing a metal from the molten salt bath on the
exposed part of the conductive substrate. Here, in the method of
manufacturing a metal product, the temperature of the molten salt
bath may be at most 250.degree. C.
[0022] The present invention further provides a metal product
manufactured using the method of manufacturing a metal product as
described above.
EFFECTS OF THE INVENTION
[0023] In accordance with the present invention, it is possible to
provide a molten salt bath allowing production of a refractory
metal deposit with high purity, high density and high denseness and
having a smooth surface, a deposit obtained using the molten salt
bath, a method of manufacturing a metal product, and a metal
product.
BRIEF DESCRIPTION OF THE DRAWING
[0024] FIG. 1 is a schematic configuration view illustrating an
exemplary method of obtaining a deposit using a molten salt bath in
accordance with the present invention.
DESCRIPTION OF THE REFERENCE SIGNS
[0025] 1 electrolytic tank, 2 molten salt bath, 3 anode, 4
cathode
BEST MODES FOR CARRYING OUT THE INVENTION
[0026] The present invention provides a molten metal salt bath
including at least one kind selected from the group consisting of
chlorine, bromine and iodine, zinc, at least two kinds of alkali
metals, and fluorine. Here, at least two kinds of lithium, sodium,
potassium and cesium are included as alkali metals in the molten
salt bath of the present invention. The form in the molten salt
bath of at least one kind selected from the group consisting of
chlorine, bromine and iodine, zinc, at least two kinds of alkali
metals, fluorine, and the like that constitute the molten salt bath
of the present invention is not specifically limited. For example,
these components may be present as ions or may be present in a
state of forming a complex in the molten salt bath. The above-noted
components that constitute the molten salt bath of the present
invention can be detected by conducting ICP (Inductively Coupled
Plasma) spectrometry for a sample prepared by dissolving the molten
salt bath of the present invention in water.
[0027] In addition to the above-noted constituent components, the
molten salt bath of the present invention may include oxygen. If
the molten salt bath of the present invention includes oxygen, a
deposit with higher purity, higher density and higher denseness and
having a smoother surface may be obtained. The form of oxygen in
the molten salt bath of the present invention is also not
specifically limited and, for example, oxygen may be present as
ions or may be present-in a state of forming a complex or in the
state of oxide.
[0028] It is noted that the presence of oxygen in the molten salt
bath of the present invention may be identified by using an inert
gas fusion infrared absorption method for the molten salt bath of
the present invention. Here, the inert gas fusion infrared
absorption method is performed, for example, as follows. First, the
molten salt bath is put into a carbon crucible in a helium gas
atmosphere and the carbon crucible is heated to cause production of
oxygen from the molten salt bath. Then, this oxygen reacts with
carbon of the carbon crucible to produce carbon monoxide or carbon
dioxide. Then, infrared radiation is applied in the atmosphere
including the produced carbon monoxide or carbon dioxide. Finally,
the amount of attenuation of infrared radiation which is caused by
absorption by carbon monoxide or carbon dioxide in the atmosphere
is examined to identify the presence and content of oxygen in the
molten salt bath.
[0029] At least one kind selected from the group consisting of
tungsten, chromium, molybdenum, tantalum, titanium, zirconium,
vanadium,, hafnium, and niobium may be included in the molten salt
bath of the present invention. These metals are refractory metals
in the fourth to sixth periods of Group IVA-Group VIA of the
periodic table. When electrolysis is performed using the molten
salt bath of the present invention including these refractory
metals, it is possible to obtain a deposit including these metals
as a main component with high purity, high density and high
denseness and having a smooth surface. The form of tungsten,
chromium, molybdenum, tantalum, titanium, zirconium, vanadium,
hafnium, or niobium in the molten salt bath of the present
invention is not specifically limited and, for example, they may be
present as ions or may be present in a state of forming a
complex.
[0030] The refractory metal content in the molten salt bath is
preferably 0.04 atomic % where the entire components that
constitute the molten salt bath is 100 atomic %, in view of
obtaining a refractory metal deposit with high purity, high density
and high denseness and having a smooth surface. The refractory
metal deposit can be obtained more efficiently with a higher
refractory metal content in the molten salt bath since deposition
with high current density is possible. However, when the refractory
metal content is increased, the melting point of the molten salt
bath rises and the temperature of the molten salt bath in
electrolysis needs to be increased. Therefore, if the refractory
metal content is increased, it may become impossible to conduct
electrolysis by immersing a conductive substrate having a resist
pattern made of a material having a low melting point such as a
resin in the molten salt bath. Thus, the refractory metal content
is preferably set as appropriate depending on a purpose.
[0031] The presence and content of the refractory metal in the
molten salt bath of the present invention can be detected and
calculated by conducting ICP spectrometry for a sample prepared by
dissolving the molten salt bath of the present invention in water.
It is noted that although the present invention aims to obtain a
refractory metal deposit with high purity, high density and high
denseness and having a smooth surface, it is needless to say that a
deposit other than a refractory metal may be obtained using the
molten salt bath of the present invention.
[0032] Preferably, the molten salt bath of the present invention is
made of at least two kinds selected from the group consisting of
sodium, potassium, and cesium as the aforementioned alkali metals,
at least one kind of chorine and bromine, zinc, and fluorine. In
this case, it is likely that a deposit with higher purity, higher
density and higher denseness and having a smoother surface can be
obtained. Here, desirably, a component other than at least two
kinds selected from the group consisting of sodium, potassium, and
cesium, at least one kind of chorine and bromine, zinc, and
fluorine is not present in the molten salt bath except for an
inevitably included component.
[0033] The zinc content in the molten salt bath of the present
invention is preferably 14 atomic % or more and 30 atomic % or
less, more preferably, 17 atomic % or more and 25 atomic % or less,
in the entire molten salt bath. If the zinc content is less than 14
atomic % or more than 30 atomic % of the entire molten salt bath, a
deposit with high purity and high density and having a smooth
surface is not likely to be obtained. On the other hand, if the
zinc content is 17 atomic % or more and 25 atomic % or less of the
entire molten salt bath, the temperature of the molten salt bath
can be set at 250.degree. C. or lower. Therefore, even when an
electroforming mold having a resist pattern of a resin such as
polymethyl methacrylate (PMMA) formed on a conductive substrate is
immersed, deformation of the resist pattern due to the temperature
of the molten salt bath can be prevented. Thus, in this case, it is
possible to manufacture a metal product by electroforming at a low
temperature of 250.degree. C. or lower as the temperature of the
molten salt bath. It is noted that the zinc content in the molten
salt bath of the present invention can be detected by conducting
ICP spectrometry for a sample prepared by dissolving the molten
salt bath of the present invention in water.
[0034] Here, for example, a substrate made of a metal alone or an
alloy, a substrate formed by plating a non-conductive substrate
such as glass with a conductive metal, or the like can be used as a
conductive substrate. A metal product is formed by depositing a
metal such as refractory metal in the molten salt bath by
electrolysis on that part of the surface of the above-noted
conductive substrate which is exposed without formation of a resist
pattern. The metal product manufactured in accordance with the
present invention includes, for example, contact probes,
micro-connectors, micro-relays, a variety of sensor parts, or the
like. The metal product manufactured in accordance with the present
invention includes, for example, RFMEMS (Radio Frequency Micro
Electro Mechanical System) such as variable capacitors, inductors,
arrays, or antennas, optical MEM members, ink jet heads, electrodes
in biosensors or power MEMS members (electrodes or the like).
[0035] If the fluorine content in the molten salt bath of the
present invention is too low, the effect of inclusion of fluorine
cannot be achieved, and if too high, the likeliness of
incorporation of fluorine into the deposit as an impurity is
increased. Therefore, the fluorine content in the entire molten
salt bath is preferably 0.1 atomic % or more and 20 atomic % or
less, and more preferably 0.1 atomic % or more and 4 atomic % or
less. It is noted that the fluorine content in the molten salt bath
of the present invention can be detected and calculated using a
fluoride ion-selective electrode for a sample prepared by
dissolving the molten salt bath of the present invention in
water.
[0036] The molten salt bath of the present invention can be
obtained by mixing at least a zinc chloride, bromide or iodide, at
least two kinds of alkali metal chloride, bromide or iodide, and a
fluorine compound, followed by heating for melting.
[0037] The resulting molten salt bath is put into an electrolytic
tank 1, for example, shown in the schematic configuration view in
FIG. 1. Then, after an anode 3 and a cathode 4 are immersed in
molten salt bath 2 put in electrolytic tank 1, electrolysis of
molten salt bath 2 is performed by feeding electric current between
anode 3 and cathode 4, whereby the metal included in molten salt
bath 2 is deposited, for example, on the surface of cathode 4,
resulting in a deposit.
[0038] Here, the deposit is preferably formed in the state in which
0.01 atomic % or more of oxygen is contained in molten salt bath 2.
In this case, it is likely that a purer deposit can be obtained.
The technique to include oxygen into molten salt bath 2 may
include, for example, performing the processes from preparation of
molten salt bath 2 to obtaining a deposit, in the air, introducing
oxygen in molten salt bath 2, preparing molten salt bath 2 mixed
with an oxide, or the like. It is noted that the above-noted oxygen
content is represented in a ratio (atomic %) where the total of the
entire components that constitute molten salt bath 2 including
oxygen is 100 atomic %. The oxygen content in molten salt bath 2
can be calculated using the aforementioned inert gas fusion
infrared absorption method.
[0039] Preferably, the surface of the deposit has surface roughness
of 3 .mu.m or less in view of obtaining a deposit having a smooth
surface. Here, in the present invention, "surface roughness" refers
to arithmetic mean roughness Ra (JIS B0601-1994).
[0040] Preferably, the relative density of the deposit is 85% or
more. If the relative density of the deposit is less than 85%,
voids in the deposit are increased so that salts are more likely to
be caught. In addition, the residual stress in the deposit
increases so that the deposit may be stripped during formation of
the deposit. Here, in the present invention, "relative density of
the deposit" is a ratio (%) of the density (g/cm.sup.3) of the
deposit to the original density (g/cm.sup.3) of the metal intended
to be formed, as expressed by the following formula:
the relative density of the deposit (%)=100.times.(the density of
the deposit)/(the original density of the metal intended to be
deposited).
EXAMPLE
Example 1
[0041] ZnCl.sub.2 (zinc chloride), NaCl (sodium chloride), KCl
(potassium chloride), and KF (potassium fluoride) powders were each
dried in a vacuum oven at 200.degree. C. for 12 hours. WCl.sub.4
(tungsten tetrachloride) powder was dried in a vacuum oven at
100.degree. C. for 12 hours. Then, after ZnCl.sub.2, NaCl and KCl
powders were each weighed in a glove box under Ar (argon)
atmosphere in a mol ratio of 60:20:20, these powders were put into
an alumina crucible in the same glove box.
[0042] In addition, after KF and WCl.sub.4 powders were each
weighed in the above-noted glove box such that there were 4 mol of
KF and 0.54 mol of WCl.sub.4 for 100 mol of the ZnCl.sub.2, NaCl
and KCl mixture put in the alumina crucible, these powders were put
into the above-noted alumina crucible. The composition (mol ratio)
of the raw materials put in the alumina crucible is shown in Table
1.
[0043] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, KF, and WCl.sub.4 was heated in the above-noted glove box to
allow the powders in the alumina crucible to be melted. Thus, 500 g
of the molten salt bath of Example 1 was prepared. The composition
(atomic %) of this molten salt bath is shown in Table 2. It is
noted that the composition of the molten salt bath shown in Table 2
is calculated based on the composition of ZnCl.sub.2, NaCl, KCl,
KF, and WCl.sub.4 contained in the above-noted alumina
crucible.
[0044] Then, a mirror-polished nickel plate having arithmetic mean
roughness Ra (JIS B0601-1994) of less than 10 nm as a cathode and a
tungsten rod having a diameter of 5 mm as an anode were immersed in
the molten salt bath of Example 1 in the above-noted glove box.
Subsequently, with the temperature of the molten salt bath kept at
250.degree. C., electric current is fed across the aforementioned
electrodes for 10 hours such that current of 3 mA per cm.sup.2 of
the nickel plate (current density 3 mA/cm.sup.2) flows.
Electrolysis performed under such electrolytic conditions (Table 3)
resulted in a deposit including tungsten on the surface of the
nickel plate serving as a cathode.
[0045] Thereafter, the nickel plate having the deposit including
tungsten was taken out from the glove box into the air, and the
deposition state, composition, surface roughness and density of the
deposit were each evaluated. The result is shown in Table 3.
[0046] It is noted that the deposition state of the deposit was
evaluated by determining. whether or not the deposition was in a
state of a film that is firmly attached to the nickel plate,
through the observation using SEM (Scanning Electron Microscope).
In this observation, if the film state was achieved, the
electrodeposition was evaluated as good, and if the deposit was
formed in a grain state or the deposit was cracked, the
electrodeposition was evaluated as no good.
[0047] In addition, the composition of the deposit was evaluated by
ICP spectrometry after the deposit was dissolved in acid. As the
amount of tungsten contained in the deposit was larger (with the
larger atomic % of tungsten (W) shown in Table 3), it was evaluated
that a higher purity was achieved. The components other than W, Zn
and O shown in Table 3 (the other fields in Table 3) were mainly
the constituent components of the molten salt bath and were present
in the cavities of the deposit. Therefore, as the amount of the
components other than W, Zn and O was smaller (with the smaller
atomic % in the other fields of Table 3), the deposit was evaluated
as having higher denseness.
[0048] Furthermore, the surface roughness of the deposit was
evaluated using a laser microscope (manufactured by KEYENCE
CORPORATION, model No. "VK-8500"). It is shown that as the numeric
value of the surface roughness shown in Table 3 is smaller, the
deposit has a smoother surface. It is noted that the surface
roughness shown in Table 3 is arithmetic mean roughness Ra (JIS
B0601-1994).
[0049] The density of the deposit was evaluated using an FIB
(Focused Ion Beam) apparatus by cutting out the vicinity of the
center of the deposit in a rectangular shape of 3 mm.times.3 mm
together with the nickel plate and thereafter calculating the
density of the deposit in the cut sample. It is noted that the
density of the deposit was calculated as follows. First, using the
FIB apparatus, the thickness of the deposit in the sample was
measured. Then, the volume of the deposit was calculated by
multiplying the measured thickness by the area (3 mm.times.3 mm) of
the surface of the deposit. On the other hand, the mass of the part
corresponding to the cut nickel plate was calculated based on the
mass of the entire nickel plate that was measured beforehand. Then,
the mass of the entire sample was measured, and the mass of the
deposit was calculated by subtracting the mass of the part
corresponding to the cut nickel plate as described above from the
measured mass of the entire sample. Finally, the density of the
deposit was calculated by dividing the mass of the deposit by the
volume of the deposit.
[0050] Furthermore, the relative density of the deposit (%) was
calculated by the. following formula based on the density of the
deposit calculated above and the original density of tungsten,
where the original density of tungsten which is a metal intended to
be deposited is 19.3 (g/cm.sup.3):
the relative density (%) of the deposit=100.times.(the density of
the deposit)/(the original density of tungsten).
[0051] As shown in Table 3, the deposit obtained by using the
molten salt bath of Example 1 was in the film-like deposition
state, and had a large amount of tungsten with high purity, and
with a small surface roughness, high density, high relative density
and high denseness.
Example 2
[0052] ZnCl.sub.2, NaCl, KCl, LiCl (lithium chloride), and KF
powders were each dried in a vacuum oven at 200.degree. C. for 12
hours. WCl.sub.4 powder was dried in a vacuum oven at 100.degree.
C. for 12 hours. Then, after ZnCl.sub.2, NaCl, KCl, and LiCl
powders were each weighed in a glove box under Ar atmosphere in a
mol ratio of 35:30:30:5, these powders were put into an alumina
crucible in the same glove box.
[0053] In addition, after the KF and WCl.sub.4 powders were each
weighed in the above-noted glove box such that there were 4 mol of
KF and 0.54 mol of WCl.sub.4 for 100 mol of the ZnCl.sub.2, NaCl,
KCl, and LiCl mixture put in the alumina crucible, these powders
were put into the above-noted alumina crucible. The composition
(mol ratio) of the raw materials put in the alumina crucible is
shown in Table 1.
[0054] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, LiCl, KF, and WCl.sub.4 was heated in the above-noted glove
box to allow the powders in the alumina crucible to be melted.
Thus, 500 g of the molten salt bath of Example 2 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
2.
[0055] Then, electrolysis was performed under the electrolytic
conditions (Table 3) similar to Example 1 except that the
temperature of the molten salt bath was kept at 430.degree. C.,
resulting in a deposit including tungsten on the surface of the
nickel plate.
[0056] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0057] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 2 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Example 3
[0058] ZnCl.sub.2, NaCl, KCl, and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. WCl.sub.4 powder was
dried in a vacuum oven at 100.degree. C. for 12 hours. Then, a
mixture was prepared in a mol ratio of ZnCl.sub.2, NaCl and KCl of
85:10:5. After KF and WCl.sub.4 powders were each weighed in the
above-noted glove box such that there were 4 mol of KF and 0.54 mol
of WCl.sub.4 for 100 mol of this mixture, these powders were put
into the above-noted alumina crucible. The composition (mol ratio)
of the raw materials put in the alumina crucible is shown in Table
1.
[0059] Thereafter, the alumina crucible was heated to allow the
powders in the alumina crucible to be melted, similarly to Example
1. Thus, a molten salt bath of Example 3 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
2.
[0060] Then, electrolysis was performed using the molten salt bath
of Example 3 under the electrolytic conditions (Table 3) similar to
Example 1 except that the temperature of the molten salt bath was
kept at 380.degree. C., resulting in a deposit including tungsten
on the surface of the nickel plate.
[0061] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0062] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 3 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Example 4
[0063] ZnCl.sub.2, NaCl, CsCl (cesium chloride), and KF powders
were each dried in a vacuum oven at 200.degree. C. for 12 hours.
WCl.sub.4 powder was dried in a vacuum oven at 100.degree. C. for
12 hours. Then, a mixture in a mol ratio of ZnCl.sub.2, NaCl, and
CsCl of 60:20:20 was put into the alumina crucible. Then, KF and
WCl.sub.4 were put into the aforementioned alumina crucible at 4
mol of KF and 0.54 mol of WCl.sub.4 for 100 mol of the mixture. The
composition (mol ratio) of the raw materials put in the alumina
crucible is shown in Table 1.
[0064] Thereafter, the alumina crucible was heated to allow the
powders in the alumina crucible to be melted, similarly to Example
1. Thus, a molten salt bath of Example 4 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
2.
[0065] Then, electrolysis was performed using the molten salt bath
of Example 4 under the electrolytic conditions (Table 3) similar to
Example 1, resulting in a deposit including tungsten on the surface
of the nickel plate.
[0066] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0067] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 4 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Example 5
[0068] ZnCl.sub.2, NaCl, KCl, KF, and WO.sub.3 (tungstic trioxide)
powders were each dried in a vacuum oven at 200.degree. C. for 12
hours. WCl.sub.4 powder was dried in a vacuum oven at 100.degree.
C. for 12 hours. After the ZnCl.sub.2, NaCl, and KCl powders were
each weighed in the above-noted glove box under Ar atmosphere in a
mol ratio of 60:20:20, these powders were put into the above-noted
alumina crucible in the same glove box.
[0069] In addition, after the KF, WCl.sub.4 and WO.sub.3 powders
were each weighed in the aforementioned glove box such that there
were 4 mol of KF, 0.27 mol of WCl.sub.4, and 0.27 mol of WO.sub.3
for 100 mol of the ZnCl.sub.2, NaCl and KCl mixture put in the
aforementioned alumina crucible, these powders were put into the
aforementioned alumina crucible. The composition (mol ratio) of the
raw materials put in the alumina crucible is shown in Table 1.
[0070] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, KF, WCl.sub.4 and WO.sub.3 was heated in the above-noted glove
box to allow the powders in the alumina crucible to be melted.
Thus, 500 g of a molten salt bath of Example 5 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
2.
[0071] Then, electrolysis was performed using the molten salt bath
of Example 5 under the electrolytic conditions (Table 3) similar to
Example 1, resulting in a deposit including tungsten on the surface
of the nickel plate.
[0072] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0073] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 5 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Example 6
[0074] ZnBr.sub.2 (zinc bromide), NaBr (sodium bromide), KBr
(potassium bromide), and KF powders were each dried in a vacuum
oven at 200.degree. C. for 12 hours. WCl.sub.4 powder was dried in
a vacuum oven at 100.degree. C. for 12 hours. After the ZnBr.sub.2,
NaBr, and KBr powders were each weighed in the above-noted glove
box under Ar atmosphere in a mol ratio of 60:20:20, these powders
were put into an alumina crucible in the same glove box.
[0075] In addition, after the KF and WCl.sub.4 powders were each
weighed in the aforementioned glove box such that there were 4 mol
of KF and 0.5 mol of WCl.sub.4 for 100 mol of the ZnBr.sub.2, NaBr,
and KBr mixture put in the aforementioned alumina crucible, these
powders were put into the aforementioned alumina crucible. The
composition (mol ratio) of the raw materials put in the alumina
crucible is shown in Table 1.
[0076] Then, the alumina crucible that contained ZnBr.sub.2, NaBr,
KBr, KF, and WCl.sub.4 was heated in the above-noted glove box to
allow the powders in the alumina crucible to be melted. Thus, 500 g
of the molten salt bath of Example 6 was prepared. The composition
(atomic %) of this molten salt bath is shown in Table 2.
[0077] Then, electrolysis was performed using the molten salt bath
of Example 6 under the electrolytic conditions (Table 3) similar to
Example 1, resulting in a deposit including tungsten on the surface
of the nickel plate.
[0078] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0079] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 6 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Example 7
[0080] ZnCl.sub.2, NaCl, KCl, and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. WCl.sub.4 powder was
dried in a vacuum oven at 100.degree. C. for 12 hours. A mixture of
ZnCl.sub.2, NaCl and KCl was prepared in a mol ratio of 49:30:21.
After the KF and WCl.sub.4 powders were each weighed in the
aforementioned glove box such that there were 4 mol of KF and 0.54
mol of WCl.sub.4 for 100 mol of this mixture, these powders were
put into the aforementioned alumina crucible. The composition (mol
ratio) of the raw materials put in the alumina crucible is shown in
Table 1.
[0081] Thereafter, similarly to Example 1, the alumina crucible was
heated to allow the powders in the alumina crucible to be melted,
whereby a molten salt bath of Example 7 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
2.
[0082] Then, electrolysis was performed using the molten salt bath
of Example 7 under the electrolytic conditions (Table 3) similar to
Example 1, resulting in a deposit including tungsten on the surface
of the nickel plate.
[0083] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0084] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 7 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Example 8
[0085] ZnCl.sub.2, NaCl, KCl, and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. WCl.sub.4 powder was
dried in a vacuum oven at 100.degree. C. for 12 hours. A mixture of
ZnCl.sub.2, NaCl and KCl was prepared in a mol ratio of 70:15:15.
After the KF and WCl.sub.4 powders were each weighed in the
aforementioned glove box such that there were 4 mol of KF and 0.54
mol of WCl.sub.4 for 100 mol of this mixture, these powders were
put into the aforementioned alumina crucible. The composition (mol
ratio) of the raw materials put in the alumina crucible is shown in
Table 1.
[0086] Thereafter, similarly to Example 1, the alumina crucible was
heated to allow the powders in the alumina crucible to be melted,
whereby a molten salt bath of Example 8 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
2.
[0087] Then, electrolysis was performed using the molten salt bath
of Example 8 under the electrolytic conditions (Table 3) similar to
Example 1, resulting in a deposit including tungsten on the surface
of the nickel plate.
[0088] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0089] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 8 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Example 9
[0090] A deposit including tungsten on the surface of the nickel
plate was obtained similarly to Example 1 except that the processes
from weighing the powders to obtaining a deposit including tungsten
were performed in the air. In Example 9, the composition (mol
ratio) of the raw materials put in the alumina crucible is shown in
Table 1 and the composition (atomic %) of the molten salt bath is
shown in Table 2. Here, the oxygen content (atomic %) in the molten
salt bath was calculated using the inert gas fusion infrared
absorption method for a sample prepared by extracting a part of the
molten salt bath. It is noted that the inclusion of oxygen in the
molten salt bath of Example 9 is thought to be caused by intrusion
of oxygen in the air.
[0091] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0092] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 9 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Example 10
[0093] All the processes from weighing the powders to melting the
powders in the alumina crucible were performed in the air. Here, in
Example 10, the composition (mol ratio) of the raw materials put in
the alumina crucible is shown in Table 1. Then, an alumina tube was
inserted into the molten salt bath in the alumina crucible, and
oxygen was introduced from the tube at a flow rate of 1 L/minute to
perform bubbling with oxygen for one hour or longer. The
composition (atomic %) of the resulting molten salt bath of Example
10 is shown in Table 2. Here, the oxygen content (atomic %) in the
molten salt bath was calculated using the inert gas fusion infrared
absorption method for a sample prepared by extracting a part of the
molten salt bath. It is noted that the inclusion of oxygen in the
molten salt bath of Example 10 is thought to be caused by intrusion
of oxygen in the air and dissolution of oxygen introduced from the
alumina tube.
[0094] Thereafter, electrolysis was performed under the
electrolytic conditions (Table 3) similar to Example 1, resulting
in a deposit including tungsten on the surface of the nickel
plate.
[0095] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0096] As shown in Table 3, the deposit obtained using the molten
salt bath of Example 10 was in the film-like deposition state, and
had a large amount of tungsten with high purity, with a small
surface roughness, high density, high relative density and high
denseness.
Comparative Example 1
[0097] ZnCl.sub.2 and NaCl powders were each dried in a vacuum oven
at 200.degree. C. for 12 hours. WCl.sub.4 powder was dried in a
vacuum oven at 100.degree. C. for 12 hours. After the ZnCl.sub.2
and NaCl powders were each weighed in the aforementioned glove box
under Ar atmosphere in a mol ratio of 60:40, these powders were put
into the aforementioned alumina crucible in the same glove box.
[0098] In addition, the WCl.sub.4 powder was weighed in the
aforementioned glove box such that there was 0.54 mol of WCl.sub.4
for 100 mol of the ZnCl.sub.2 and NaCl mixture put in the
aforementioned alumina crucible. Thereafter, the WCl.sub.4 powder
was put into the aforementioned alumina crucible. The composition
(mol ratio) of the raw materials put in the alumina crucible is
shown in Table 1.
[0099] Then, the alumina crucible that contained ZnCl.sub.2, NaCl
and WCl.sub.4 was heated in the aforementioned glove box to allow
the powders to be melted. Thus, 500 g of a molten salt bath of
Comparative Example 1 was prepared. The composition (atomic %) of
this molten salt bath is shown in Table 2.
[0100] Then, electrolysis was performed using the molten salt bath
of Comparative Example 1 under the electrolytic conditions (Table
3) similar to Example 1 except that the temperature of this molten
salt bath was set at 400.degree. C. Thus, a deposit including
tungsten on the surface of the nickel plate was obtained.
[0101] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0102] As shown in Table 3, the deposit obtained using the molten
salt bath of Comparative Example 1 was in the grain-like deposition
state, and had an extremely small amount of tungsten, with a large
surface roughness, with low denseness, density and relative
density, as compared with the deposits of Examples 1-10.
Comparative Example 2
[0103] ZnCl.sub.2, NaCl and KCl powders were each dried in a vacuum
oven at 200.degree. C. for 12 hours. WCl.sub.4 powder was dried in
a vacuum oven at 100.degree. C. for 12 hours. After the ZnCl.sub.2,
NaCl and KCl powders were each weighed in the glove box under Ar
atmosphere in a mol ratio of 60:20:20, these powders were put into
the alumina crucible in the same glove box.
[0104] In addition, WCl.sub.4 powder was weighed in the
aforementioned glove box such that there was 0.54 mol of WCl.sub.4
for 100 mol of the ZnCl.sub.2, NaCl and KCl mixture put in the
aforementioned alumina crucible. Thereafter, the WCl.sub.4 powder
was put into the aforementioned alumina crucible. The composition
(mol ratio) of the raw materials put in the alumina crucible is
shown in Table 1.
[0105] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl and WCl.sub.4 was heated in the aforementioned glove box to
allow the powders to be melted. Thus, 500 g of a molten salt bath
of Comparative Example 2 was prepared. The composition (atomic %)
of this molten salt bath is shown in Table 2.
[0106] Then, electrolysis was performed using the molten salt bath
of Comparative Example 2 under the electrolytic conditions (Table
3) similar to Example 1. Thus, a deposit including tungsten on the
surface of the nickel plate was obtained.
[0107] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 3.
[0108] As shown in Table 3, the deposit obtained using the molten
salt bath of Comparative Example 2 was cracked, and had an
extremely small amount of tungsten, with a large surface roughness,
with low denseness, density and relative density as compared with
the deposits of Examples 1-10.
TABLE-US-00001 TABLE 1 Composition (mol ratio) of Raw Materials
ZnCl.sub.2 NaCl KCl LiCl CsCl ZnBr.sub.2 NaBr KBr KF WCl.sub.4
WO.sub.3 Example 1 60 20 20 0 0 0 0 0 4 0.54 0 Example 2 35 30 30 5
0 0 0 0 4 0.54 0 Example 3 85 10 5 0 0 0 0 0 4 0.54 0 Example 4 60
20 0 0 20 0 0 0 4 0.54 0 Example 5 60 20 20 0 0 0 0 0 4 0.27 0.27
Example 6 0 0 0 0 0 60 20 20 4 0.50 0 Example 7 49 30 21 0 0 0 0 0
4 0.54 0 Example 8 70 15 15 0 0 0 0 0 4 0.54 0 Example 9 60 20 20 0
0 0 0 0 4 0.54 0 Example 10 60 20 20 0 0 0 0 0 4 0.54 0 Comparative
60 40 0 0 0 0 0 0 0 0.54 0 Example 1 Comparative 60 20 20 0 0 0 0 0
0 0.54 0 Example 2
TABLE-US-00002 TABLE 2 Composition (atomic %) of Molten Salt Bath
Zn Na K Li Cs Cl Br W F O Example 1 22.16 7.39 8.87 0 0 59.90 0
0.20 1.48 0 Example 2 14.25 12.21 13.84 2.03 0 55.82 0 0.22 1.63 0
Example 3 28.75 3.38 3.04 0 0 63.30 0 0.18 1.35 0 Example 4 22.16
7.39 1.48 0 7.39 59.90 0 0.20 1.48 0 Example 5 22.19 7.40 8.87 0 0
59.56 0 0.20 1.48 0.30 Example 6 22.18 7.39 8.87 0 0 0.74 59.15
0.19 1.48 0 Example 7 18.83 11.53 9.61 0 0 58.28 0 0.21 1.54 0
Example 8 24.94 5.34 6.77 0 0 61.33 0 0.19 1.43 0 Example 9 22.14
7.38 8.86 0 0 59.84 0 0.20 1.48 0.10 Example 10 22.10 7.37 8.84 0 0
59.72 0 0.20 1.47 0.30 Comparative 22.84 15.22 0 0 0 61.73 0 0.21 0
0 Example 1 Comparative 22.84 7.61 7.61 0 0 61.73 0 0.21 0 0
Example 2
TABLE-US-00003 TABLE 3 electrolytic conditions deposit current
composition surface relative temperature density time deposition
(atomic %) roughness density density (.degree. C.) (mA/cm.sup.2)
(hour) state W Zn O others (.mu.m) (g/cm.sup.3) (%) Example 1 250 3
10 film 95 0 3 2 0.8 17.9 92.7 Example 2 430 3 10 film 93 1 4 2 1.2
17.3 89.6 Example 3 380 3 10 film 91 1 5 3 2.3 17.5 90.7 Example 4
250 3 10 film 94 0 4 2 0.7 17.7 91.7 Example 5 250 3 10 film 98 0 1
1 0.2 18.8 97.4 Example 6 250 3 10 film 93 1 3 3 1.1 17.5 90.7
Example 7 250 3 10 film 93 1 4 2 1.1 17.5 90.7 Example 8 250 3 10
film 92 1 4 3 1.3 17.4 90.2 Example 9 250 3 10 film 97 0 1 2 0.9
17.6 91.2 Example 10 250 3 10 film 98 0 1 1 0.7 17.5 90.7
Comparative 400 3 10 grain 50 2 12 36 18.6 14.2 73.6 Example 1
Comparative 250 3 10 cracking 20 35 10 35 29.3 9.8 50.8 Example
2
[0109] As can be seen from Table 2 and Table 3, when the molten
salt bath including fluorine of Examples 1-10 was used, such
deposits could be obtained that had a high purity of tungsten, had
high density, high relative density and high denseness, and had a
smooth surface, as compared with using the molten salt bath of
Comparative Examples 1-2 not including fluorine.
[0110] Furthermore, as can be seen from Table 2 and Table 3, when
the molten salt bath of Example 1 and Examples 4-10 was used that
had a zinc content of 17 atomic % or more and 25 atomic % or less
with respect to the entire molten salt bath, the deposits could be
obtained at a lower temperature of the molten salt bath such as
250.degree. C., as compared with using the molten salt bath of
Examples 2-3.
Example 11
[0111] ZnCl.sub.2, NaCl, KCl, and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. Then, after the
ZnCl.sub.2, NaCl and KCl powders were each weighed in the
aforementioned glove box under Ar atmosphere in a mol ratio of
60:20:20, these powders were put into the aforementioned alumina
crucible in the same glove box.
[0112] In addition, KF and MoCl.sub.3 (molybdenum trichloride)
powders were each weighed in the aforementioned glove box such that
there were 4 mol of KF and 0.54 mol of MoCl.sub.3 for 100 mol of
the ZnCl.sub.2, NaCl and KCl mixture put in the aforementioned
alumina crucible. Thereafter, these powders were put into the
aforementioned alumina crucible. The composition (mol ratio) of the
raw materials put in the alumina crucible is shown in Table 4.
[0113] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, KF and MoCl.sub.3 was heated in the aforementioned glove box
to allow the powders in the alumina crucible to be melted. Thus,
500 g of a molten salt bath of Example 11 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
5.
[0114] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 11. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 150 mV for
three hours using a three electrode method in which the potential
of the nickel plate serving as a cathode was controlled, resulting
in a deposit including molybdenum on the surface of the nickel
plate serving as a cathode.
[0115] Thereafter, the deposition state, composition, surface
roughness, and density of the deposit were evaluated in a method
similar to Example 1. Furthermore, the relative density (%) of the
deposit was calculated by the following formula based on the
density of the deposit as calculated above and the original density
of molybdenum, where the original density of molybdenum, which is a
metal intended to be deposited, is 10.22 (g/cm.sup.3).
[0116] The result is shown in Table 6.
the relative density (%) of the deposit=100.times.(the density of
the deposit)/(the original density of molybdenum)
[0117] As shown in Table 6, the deposit (3 .mu.m thick) obtained
using the molten salt bath of Example 11 was in the film-like
deposition state, and had a large amount of molybdenum with high
purity, with a small-surface roughness, with high density, high
relative density and high denseness.
Example 12
[0118] ZnCl.sub.2, NaCl, KCl and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. After the ZnCl.sub.2,
NaCl and KCl powders were each weighed in the aforementioned glove
box under Ar atmosphere in a mol ratio of 60:20:20, these powders
were put into the alumina crucible in the same glove box.
[0119] In addition, KF and MoCl.sub.5 (molybdenum pentachloride)
powders were each weighed in the aforementioned glove box such that
there were 4 mol of KF and 0.54 mol of MoCl.sub.5 for 100 mol of
the ZnCl.sub.2, NaCl and KCl mixture put in the aforementioned
alumina crucible. Thereafter, these powders were put into the
aforementioned alumina crucible. The composition (mol ratio) of the
raw materials put in the alumina crucible is shown in Table 4.
[0120] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, KF and MoCl.sub.5 was heated in the aforementioned glove box
to allow the powders in the alumina crucible to be melted. Thus,
500 g of a molten salt bath of Example 12 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
5.
[0121] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 12. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 150 mV for
three hours using a three electrode method in which the potential
of the nickel plate serving as a cathode was controlled, resulting
in a deposit including molybdenum on the surface of the nickel
plate serving as a cathode.
[0122] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 11. The result is shown in
Table 6.
[0123] As shown in Table 6, the deposit (0.5 .mu.m thick) obtained
using the molten salt bath of Example 12 was in the film-like
deposition state, and had a large amount of molybdenum with high
purity, with a small surface roughness, with high density, high
relative density and high denseness.
Example 13
[0124] ZnCl.sub.2, NaCl, KCl and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. In addition, WO.sub.3
powder was dried in a vacuum oven at 100.degree. C. for 12 hours.
After the ZnCl.sub.2, NaCl and KCl powders were each weighed in the
glove box under Ar atmosphere in a mol ratio of 60:20:20, these
powders were put into the alumina crucible in the same glove box.
in addition, KF and WO.sub.3 powders were each weighed in the
aforementioned glove box such that there were 4 mol of KF and 0.54
mol of WO.sub.3 for 100 mol of the ZnCl.sub.2, NaCl and KCl mixture
put in the aforementioned alumina crucible. Thereafter, these
powders were put into the aforementioned alumina crucible. The
composition (mol ratio) of the raw materials put in the alumina
crucible is shown in Table 4.
[0125] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, KF and WO.sub.3 was heated in the aforementioned glove box to
allow the powders in the alumina crucible to be melted. Thus, 500 g
of a molten salt bath of Example 13 was prepared. The composition
(atomic %) of this molten salt bath is shown in Table 5.
[0126] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 13. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 60 mV for
three hours using a three electrode method in which the potential
of the nickel plate serving as a cathode was controlled, resulting
in a deposit including tungsten on the surface of the nickel plate
serving as a cathode.
[0127] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 1. The result is shown in
Table 6.
[0128] As shown in Table 6, the deposit (0.5 .mu.m thick) obtained
using the molten salt bath of Example 13 was in the film-like
deposition state, and had a large amount of tungsten with high
purity, with a small surface roughness, with high density, high
relative density and high denseness.
Example 14
[0129] ZnCl.sub.2, NaCl, KCl and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. Then, after ZnCl.sub.2,
NaCl and KCl powders were each weighed in the aforementioned glove
box under Ar atmosphere in a mol ratio of 60:20:20, these powders
were put into the alumina crucible in the same glove box.
[0130] In addition, KF and Ta.sub.2O.sub.5 (ditantalum pentaoxide)
powders were each weighed in the aforementioned glove box such that
there were 4 mol of KF and 0.54 mol of Ta.sub.2O.sub.5 for 100 mol
of the ZnCl.sub.2, NaCl and KCl mixture put in the aforementioned
alumina crucible. Thereafter, these powders were put into the
aforementioned alumina crucible. The composition (mol ratio) of the
raw materials put in the alumina crucible is shown in Table 4.
[0131] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, KF and Ta.sub.2O.sub.5 was heated in the aforementioned glove
box to allow the powders in the alumina crucible to be melted.
Thus, 500 g of a molten salt bath of Example 14 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
5.
[0132] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 14. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 60 mV for
three hours using a three electrode method in which the potential
of the nickel plate serving as a cathode was controlled, resulting
in a deposit including tantalum on the surface of the nickel plate
serving as a cathode.
[0133] Thereafter, the deposition state, composition, surface
roughness, and density of the deposit were evaluated in a method
similar to Example 1. Furthermore, the relative density (%) of the
deposit was calculated by the following formula based on the
density of the deposit as calculated above and the original density
of tantalum, where the original density of tantalum, which is a
metal intended to be deposited, is 16.65 (g/cm.sup.3).
[0134] The result is shown in Table 6.
the relative density (%) of the deposit=100.times.(the density of
the deposit)/(the original density of tantalum)
[0135] As shown in Table 6, the deposit (0.5 .mu.m thick) obtained
using the molten salt bath of Example 14 was in the film-like
deposition state, and had a large amount of tantalum with high
purity, with a small surface roughness, with high density, high
relative density and high denseness.
Example 15
[0136] ZnCl.sub.2, NaCl, KCl and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. Then, after the
ZnCl.sub.2, NaCl and KCl powders were each weighed in the
aforementioned glove box under Ar atmosphere in a mol ratio of
60:20:20, these powders were put into the alumina crucible in the
same glove box.
[0137] In addition, KF powder was weighed in the aforementioned
glove box at 4 mol for 100 mol of the ZnCl.sub.2, NaCl and KCl
mixture put in the aforementioned alumina crucible. Then, the
weighed KF powder was put into the aforementioned alumina
crucible.
[0138] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, and KF was heated in the aforementioned glove box to allow the
powders in the alumina crucible to be melted. Thereafter,
TiCl.sub.4 was weighed in the above-noted glove box at 0.54 mol for
100 mol of the ZnCl.sub.2, NaCl and KCl mixture put in the
aforementioned alumina crucible. The weighed TiCl.sub.4 was added
to the aforementioned alumina crucible. Thus, 500 g of a molten
salt bath of Example 15 was prepared. The composition (mol ratio)
of the raw materials used for preparing this molten salt bath is
shown in Table 4 and the composition (atomic %) of this molten salt
bath is shown in Table 5.
[0139] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 15. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 60 mV for
six hours using a three electrode method in which the potential of
the nickel plate serving as a cathode was controlled, resulting in
a deposit including titanium on the surface of the nickel plate
serving as a cathode.
[0140] Thereafter, the deposition state, composition, surface
roughness, and density of the deposit were evaluated in a method
similar to Example 1. Furthermore, the relative density (%) of the
deposit was calculated by the following formula based on the
density of the deposit as calculated above and the original density
of titanium, where the original density of titanium, which is a
metal intended to be deposited, is 4.54 (g/cm.sup.3).
[0141] The result is shown in Table 6.
the relative density (%) of the deposit=100.times.(the density of
the deposit)/(the original density of titanium)
[0142] As shown in Table 6, the deposit (0.1 .mu.m thick) obtained
using the molten salt bath of Example 15 was in the film-like
deposition state, and had a large amount of titanium with high
purity, with a small surface roughness, with high density, high
relative density and high denseness.
Example 16
[0143] ZnCl.sub.2, NaCl, KCl and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. Then, after the
ZnCl.sub.2, NaCl and KCl powders were each weighed in the
aforementioned glove box under Ar atmosphere in a mol ratio of
60:20:20, these powders were put into the alumina crucible in the
same glove box.
[0144] In addition, KF powder was weighed in the aforementioned
glove box at 4 mol for 100 mol of the ZnCl.sub.2, NaCl and KCl
mixture put in the aforementioned alumina crucible. Then, the
weighed KF powder was put into the aforementioned alumina
crucible.
[0145] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, and KF was heated in the aforementioned glove box to allow the
powders in the alumina crucible to be melted. Thereafter,
TiCl.sub.4 was weighed in the above-noted glove box at 1.1 mol for
100 mol of the ZnCl.sub.2, NaCl and KCl mixture put in the
aforementioned alumina crucible. The weighed TiCl.sub.4 was added
to the aforementioned alumina crucible. Thus, 500 g of a molten
salt bath of Example 16 was prepared. The composition (mol ratio)
of the raw materials used for preparing this molten salt bath is
shown in Table 4 and the composition (atomic %) of the molten salt
bath is shown in Table 5.
[0146] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 16. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 60 mV for
three hours using a three electrode method in which the potential
of the nickel plate serving as a cathode was controlled, resulting
in a deposit including titanium on the surface of the nickel plate
serving as a cathode.
[0147] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 15. The result is shown in
Table 6.
[0148] As shown in Table 6, the deposit (0.1 .mu.m thick) obtained
using the molten salt bath of Example 16 was in the film-like
deposition state, and had a large amount of titanium with high
purity, and with a small surface roughness, with high density, high
relative density and high denseness.
Example 17
[0149] ZnCl.sub.2, NaCl, KCl and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. After the ZnCl.sub.2,
NaCl and KCl powders were weighed in the glove box under Ar
atmosphere in a mol ratio of 60:20:20, these powders were put into
the alumina crucible in the same glove box.
[0150] In addition, KF powder was weighed in the aforementioned
glove box at 4 mol for 100 mol of the ZnCl.sub.2, NaCl and KCl
mixture put in the aforementioned alumina crucible. Then, the
weighed KF powder was put into the aforementioned alumina
crucible.
[0151] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, and KF was heated in the aforementioned glove box to allow the
powders in the alumina crucible to be melted. Thereafter,
TiCl.sub.4 was weighed in the above-noted glove box at 2.5 mol for
100 mol of the ZnCl.sub.2, NaCl and KCl mixture put in the
aforementioned alumina crucible. The weighed TiCl.sub.4 was added
to the aforementioned alumina crucible. Thus, 500 g of a molten
salt bath of Example 17 was prepared. The composition (mol ratio)
of the raw materials used for preparing this molten salt bath is
shown in Table 4 and the composition (atomic %) of the molten salt
bath is shown in Table 5.
[0152] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 17. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 60 mV for
eight hours using a three electrode method in which the potential
of the nickel plate serving as a cathode was controlled, resulting
in a deposit including titanium on the surface of the nickel plate
serving as a cathode.
[0153] Thereafter, the deposition state, composition, surface
roughness, density, and relative density of the deposit were
evaluated in a method similar to Example 15. The result is shown in
Table 6.
[0154] As shown in Table 6, the deposit (0.5 .mu.m thick) obtained
using the molten salt bath of Example 17 was in the film-like
deposition state, and had a large amount of titanium with high
purity, with a small surface roughness, with high density, high
relative density and high denseness.
Example 18
[0155] ZnCl.sub.2, NaCl, KCl and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. Then, after the
ZnCl.sub.2, NaCl and KCl powders were each weighed in the glove box
under Ar atmosphere in a mol ratio of 60:20:20, these powders were
put into the alumina crucible in the same glove box.
[0156] In addition, KF and NbCl.sub.5 (niobium pentachloride)
powders were each weighed in the aforementioned glove box such that
there were 4 mol of KF and 0.54 mol of NbCl.sub.5 for 100 mol of
the ZnCl.sub.2, NaCl and KCl mixture put in the aforementioned
alumina crucible. Thereafter, these powders were put into the
aforementioned alumina crucible. The composition (mol ratio) of the
raw materials put in the alumina crucible is shown in Table 4.
[0157] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, KF and NbCl.sub.5 was heated in the aforementioned glove box
to allow the powders in the alumina crucible to be melted. Thus,
500 g of a molten salt bath of Example 18 was prepared. The
composition (atomic %) of this molten salt bath is shown in Table
5.
[0158] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 18. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 60 mV for
three hours using a three electrode method in which the potential
of the nickel plate serving as a cathode was controlled, resulting
in a deposit including niobium on the surface of the nickel plate
serving as a cathode.
[0159] Thereafter, the deposition state, composition, surface
roughness, and density of the deposit were evaluated in a method
similar to Example 1. Furthermore, the relative density (%) of the
deposit was calculated by the following formula based on the
density of the deposit as calculated above and the original density
of niobium, where the original density of niobium, which is a metal
intended to be deposited, is 8.57 (g/cm.sup.3).
[0160] The result is shown in Table 6.
the relative density (%) of the deposit=100.times.(the density of
the deposit)/(the original density of niobium)
[0161] As shown in Table 6, the deposit (0.5 .mu.m thick) obtained
using the molten salt bath of Example 18 was in the film-like
deposition state, and had a large amount of niobium with high
purity, with a small surface roughness, with high density, high
relative density and high denseness.
Example 19
[0162] ZnCl.sub.2, NaCl, KCl and KF powders were each dried in a
vacuum oven at 200.degree. C. for 12 hours. Then, after the
ZnCl.sub.2, NaCl and KCl powders were each weighed in the glove box
under Ar atmosphere in a mol ratio of 60:20:20, these powders were
put into the alumina crucible in the same glove box.
[0163] In addition, KF and VCl.sub.2 (vanadium dichloride) powders
were each weighed in the aforementioned glove box such that there
were 4 mol of KF and 0.54 mol of VCl.sub.2 for 100 mol of the
ZnCl.sub.2, NaCl and KCl mixture put in the aforementioned alumina
crucible. Thereafter, these powders were put into the
aforementioned alumina crucible. The composition (mol ratio) of the
raw materials put in the alumina crucible is shown in Table 4.
[0164] Then, the alumina crucible that contained ZnCl.sub.2, NaCl,
KCl, KF and VCl.sub.2 was heated in the aforementioned glove box to
allow the powders in the alumina crucible to be melted. Thus, 500 g
of a molten salt bath of Example 19 was prepared. The composition
(atomic %) of this molten salt bath is shown in Table 5.
[0165] Then, in the aforementioned glove box, a mirror-polished
nickel plate having arithmetic mean roughness Ra of less than 10 nm
as a cathode, a tungsten rod having a diameter of 5 mm as an anode,
and a zinc rod having a diameter of 5 mm as a reference electrode
were immersed in the molten salt bath of Example 19. Then, with the
temperature of this molten salt bath kept at 250.degree. C.,
electrolysis was performed under the electrolytic conditions (Table
6) with a potential between the cathode and the anode of 60 mV for
three hours using a three electrode method in which the potential
of the nickel plate serving as a cathode was controlled, resulting
in a deposit including vanadium on the surface of the nickel plate
serving as a cathode.
[0166] Thereafter, the deposition state, composition, surface
roughness, and density of the deposit were evaluated in a method
similar to Example 1. Furthermore, the relative density (%) of the
deposit was calculated by the following formula based on the
density of the deposit as calculated above and the original density
of vanadium, where the original density of vanadium, which is a
metal intended to be deposited, is 6.11 (g/cm.sup.3). The result is
shown in Table 6.
[0167] As shown in Table 6, the deposit (0.5 .mu.m thick) obtained
using the molten salt bath of Example 19 was in the film-like
deposition state, and had a large amount of vanadium with high
purity, with a small surface roughness, with high density, high
relative density and high denseness.
TABLE-US-00004 TABLE 4 Composition (mol ratio) of Raw Materials
ZnCl.sub.2 NaCl KCl KF MoCl.sub.3 MoCl.sub.5 WO.sub.3
Ta.sub.2O.sub.5 TiCl.sub.4 NbCl.sub.5 VCl.sub.2 Example 11 60 20 20
4 0.54 0 0 0 0 0 0 Example 12 60 20 20 4 0 0.54 0 0 0 0 0 Example
13 60 20 20 4 0 0 0.54 0 0 0 0 Example 14 60 20 20 4 0 0 0 0.54 0 0
0 Example 15 60 20 20 4 0 0 0 0 0.54 0 0 Example 16 60 20 20 4 0 0
0 0 1.1 0 0 Example 17 60 20 20 8 0 0 0 0 2.5 0 0 Example 18 60 20
20 4 0 0 0 0 0 0.54 0 Example 19 60 20 20 4 0 0 0 0 0 0 0.54
TABLE-US-00005 TABLE 5 Composition (atomic %) of Molten Salt Bath
Zn Na K Cl O F W Mo Ta Ti Nb V Example 11 22.21 7.40 8.88 59.82 0
1.48 0 0.20 0 0 0 0 Example 12 22.12 7.37 8.85 59.98 0 1.47 0 0.20
0 0 0 0 Example 13 22.21 7.40 8.88 59.22 0.60 1.48 0.20 0 0 0 0 0
Example 14 22.08 7.36 8.83 58.87 0.99 1.47 0 0 0.40 0 0 0 Example
15 22.16 7.39 8.87 59.90 0 1.48 0 0 0 0.20 0 0 Example 16 21.95
7.32 8.78 60.10 0 1.46 0 0 0 0.40 0 0 Example 17 20.80 6.93 9.71
58.93 0 2.77 0 0 0 0.87 0 0 Example 18 22.12 7.37 8.85 59.98 0 1.47
0 0 0 0 0.20 0 Example 19 22.25 7.42 8.90 59.74 0 1.48 0 0 0 0 0
0.20
TABLE-US-00006 TABLE 6 deposits electrolytic conditions surface
relative temperature potential time deposition composition (atomic
%) roughness density density (.degree. C.) (mV) (hr) state W Mo Ta
Ti Nb V Zn O others (.mu.m) (g/cm.sup.3) (%) Example 11 250 150 3
film 0 99 0 0 0 0 0 0.5 0.5 2.6 9.8 95.9 Example 12 250 150 3 film
0 98 0 0 0 0 0 1.7 0.3 1.5 10.1 98.8 Example 13 250 60 3 film 99 0
0 0 0 0 0 0.7 0.3 0.1 18.8 97.4 Example 14 250 60 3 film 0 0 99.1 0
0 0 0 0.1 0.8 1.9 15.1 90.7 Example 15 250 60 6 film 0 0 0 99 0 0 0
0.2 0.8 0.8 4.1 90.3 Example 16 250 60 3 film 0 0 0 99.1 0 0 0 0.2
0.7 1.4 4.2 92.5 Example 17 250 60 8 film 0 0 0 98.9 0 0 0 0.3 0.8
2.3 4.1 90.3 Example 18 250 60 3 film 0 0 0 0 99.1 0 0 0.1 0.8 3.2
8.1 94.5 Example 19 250 60 3 film 0 0 0 0 0 98.2 0 0.5 1.3 2.6 5.8
94.9
Example 20
[0168] A titanium layer was formed by sputtering titanium at a
thickness of 0.3 .mu.m on a surface of a disk-like silicon
substrate having a diameter of 3 inches. Then, a photoresist of a
width of 1 cm.times.a length of 1 cm.times.a thickness of 30 .mu.m,
made of PMMA, was applied on the titanium layer. Then, SR light
(synchrotron radiation) was applied to a part of the photoresist,
and that part of the photoresist which was irradiated with SR light
was selectively removed, whereby a stripe-like resist pattern was
formed on the titanium layer with line/space of 50 .mu.m/50
.mu.m.
[0169] Then, using the above-noted silicon substrate having the
resist pattern formed thereon as a cathode and a tungsten rod as an
anode, these electrodes were immersed in 1000 g of molten salt bath
having the same composition as the molten salt bath of Example 6 in
the glove box under Ar atmosphere. Then, with the molten salt bath
kept at 250.degree. C., constant-current electrolysis was performed
by feeding electric current of 3 mA per cm.sup.2 of the titanium
layer on the silicon substrate (current density 3 mA/cm.sup.2)
across these electrodes for 60 hours, resulting in a deposit
including tungsten on the titanium layer.
[0170] After completion of the constant-current electrolysis, the
silicon substrate was taken out from the glove box. Then, the
silicon substrate was washed with water in order to remove salt
attached to the silicon substrate. Next, after the silicon
substrate was dried, plasma ashing was performed using a mixture
gas of CF.sub.4 (carbon tetrafluoride) and O.sub.2 (oxygen),
whereby the photoresist on the titanium layer was removed. Finally,
the deposit on the titanium layer was mechanically stripped,
resulting in an electroformed product with high purity of tungsten,
with high density and high denseness and having a smooth
surface.
[0171] It should be understood that the embodiments and examples
disclosed herein are not limitative but illustrative in all
aspects. The scope of the present invention is shown not in the
foregoing description but in the claims, and all changes within the
meaning and range of equivalency of the claims are intended to be
embraced therein.
INDUSTRIAL APPLICABILITY
[0172] The molten salt bath in accordance with the present
invention contains at least one kind selected from the group
consisting of chlorine, bromine and iodine, zinc, at least two
kinds of alkali metals, and fluorine, so that the use of the molten
salt bath of the present invention results in a deposit with high
purity, high density and high denseness and having a smooth
surface.
* * * * *