JP2003105564A - Method of manufacturing corrosion resistant metallic member and corrosion resistant metallic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a corrosion resistant metallic member which has a high degree of a corrosion resistance and is particularly useful as a separator for fuel cells and to provide a corrosion resistant metallic member. SOLUTION: When thin noble metal layers 21b and 31b are formed on both surfaces of a metallic base material and are molded to peak and valley shapes by compression working, pinholes generated in forming the thin-film layers remain as 42a, 45a, 51a, 54a, etc., and the metallic base material is exposed in these segments. These exposed sections are treated by a liquid phase system containing a peroxide or ozone in order to prevent the corrosion thereof. Oxides 61, 62, 71 and 72 are formed by this treatment, by which the thin-film layers are restored.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a corrosion-resistant metal member and a corrosion-resistant metal member. The metal member is required to have a high degree of corrosion resistance depending on its application. For example,
When a metal member is used as a fuel cell separator, the metal member is required to have high corrosion resistance in addition to conductivity and airtightness. The present invention relates to a method for manufacturing a corrosion-resistant metal member and a corrosion-resistant metal member that meet such requirements.

[0002]

2. Description of the Related Art Conventionally, as a corrosion resistant metal member,
C on the surface of a member made of stainless steel, Ni-based alloy, Ti alloy or the like, or of a member made of steel or stainless steel
A metal thin film layer of u, Cr, Ni, Au, Ag or the like is used. Among such corrosion-resistant metal members, as a separator for a fuel cell, a metal plate material is formed into a predetermined shape, and one surface thereof is plated with gold (JP-A-10-228914), and a metal plate shape is formed into a predetermined shape. Then, after forming a metal thin film layer on at least one side of the metal thin film layer, the pinholes in the metal thin film layer are sealed by roller pressure, anodic oxidation or resin coating (Japanese Patent Laid-Open No. 2001-68).
129) and the like have been proposed. However, in these conventional means, the corrosion resistance of the produced corrosion-resistant metal member is still insufficient, and among them, the material of the metal used as the base is limited, and there is also the problem that it takes time and labor to produce the corrosion-resistant metal member. There is.

[0003]

The problem to be solved by the present invention is to provide a method for easily producing a corrosion-resistant metal member having a high degree of corrosion resistance, without limiting the material of the metal used as the base. And a corrosion-resistant metal member obtained by such a manufacturing method.

[0004]

According to the present invention for solving the above problems, a noble metal thin film layer is formed on a required portion of the surface of a metal base material, the noble metal thin film layer is subjected to compression processing, and then a peroxide or ozone is used. The present invention relates to a method for producing a corrosion-resistant metal member, which comprises performing anticorrosion treatment in a liquid phase system containing Further, the present invention is
The present invention relates to a corrosion resistant metal member obtained by the manufacturing method.

In the method of manufacturing a corrosion-resistant metal member according to the present invention, first, a noble metal thin film layer is formed on a required portion of the surface of a metal base material. The shape and material of the metal base material is not particularly limited, and can be selected in relation to the intended use of the corrosion-resistant metal member, but in terms of moldability, economy, productivity, etc., it is preferable to use a metal plate material, Fe, Ni, Ti, Cu
It is preferable to use a metal selected from the group consisting of Al and Al or an alloy based on the metal, and it is more preferable to use a plate made of stainless steel. When using a metal plate material as the metal base material, usually a noble metal thin film layer is formed on a required portion of one surface, if necessary, on both surfaces thereof, but when the obtained corrosion-resistant metal member is used as a fuel cell separator, , A noble metal thin film layer is formed on a required portion of at least one surface corresponding to the contact surface side with the electrode.

The material of the noble metal thin film layer formed on the required portion of the surface of the metal base material is not particularly limited, and can be selected in relation to the intended use of the corrosion resistant metal member. Corrosion resistance, conductivity, durability and productivity Etc., Au, Pt, Pd, A
It is preferable to use one metal selected from g, Rh and Ru or an alloy based on the one metal. The formation method of the noble metal thin film layer is not particularly limited, but for the same reason,
At least one means selected from plating, screen printing, PVD processing and CVD processing is preferable, and plating is particularly preferable. The thickness of the noble metal thin film layer is also not particularly limited, but for the same reason, particularly in terms of corrosion resistance, 0.1 to 1
The thickness is preferably 00 nm, more preferably 1 to 50 nm.

In the method of manufacturing the corrosion-resistant metal member according to the present invention, the one having the noble metal thin film layer formed as described above is then compression processed. The compression process may be performed only on the noble metal thin film layer, or may be performed on the metal base material together with the noble metal thin film layer, and in the latter case, for example, it can be performed using a rolling roller. The compression process improves the adhesion of the noble metal thin film layer to the metal base material and densifies the noble metal thin film layer itself, and at the same time reduces and reduces pinholes and the like formed in the noble metal thin film layer. The degree of compression processing is not particularly limited, but it is preferable that the compression rate be 5% or more in terms of sufficiently reducing and reducing pinholes and the like while promoting the above-mentioned adhesion and densification. More preferably, the compression rate is 10 to 60%. Here, for example, the compression ratio in the case of compressing a metal base material on which a noble metal thin film layer is formed is {1- (, where T ₀ is the thickness before the compression process and T ₁ is the thickness after the compression process). T ₁ / T ₀ )} × 100
It is the value obtained by.

In the method for producing a corrosion-resistant metal member according to the present invention, finally, the compression-processed product as described above is subjected to anticorrosion treatment in a liquid phase system containing peroxide or ozone. Even if it is compressed as described above, small pinholes etc. remain in the precious metal thin film layer including those that are invisible to the naked eye, and the metal base material is exposed through such pinholes. However, since the metal base material corrodes in the exposed portion, the exposed portion is subjected to anticorrosion treatment to oxidize its surface, and the corrosion resistance of the obtained corrosion resistant metal member is improved.

Specifically, the anticorrosion treatment is carried out by compression as described above.
The processed product is converted into a liquid phase system containing peroxide or ozone.
It is done by dipping. As the peroxide used here
For M_TwoO_TwoType (M is H, Na, K, NH_Four, Ag
Etc.), MO_TwoType (M is Ca, Sr, Ba, Zn, etc.), M
O_Three・ NH_TwoIn addition to O-type (M is Ti, etc.) peroxides, M
_TwoS_TwoO₈Type (M is H, Na, K, NH_FourEtc.) Peru
Kiso sulphate and its salts, M_FourP_TwoO₈Type (M is H, K, etc.)
Peroxophosphoric acid and its salts, M_TwoCO_FourType (M is Na,
K) and M_TwoC_TwoO₆Type (M is Na, K, NH_FourEtc.)
Peroxocarbonate, MBO_ThreeType (M is Na, K, etc.)
Ruoxoborate, CO (NH_Two)_Two・ H _TwoO_TwoType of urine
Such as hydrogen peroxide addition product, but economical and production
It is preferable to use hydrogen peroxide from the viewpoint of properties and the like.

The above liquid phase system containing peroxide or ozone is basically formed of peroxide or ozone and a solvent for dissolving or suspending the peroxide or ozone. Water, alcohol, a mixture thereof, or the like can be used in relation to the oxide or ozone, but in addition to these, it is further formed with an alkaline agent or an acid agent. N
Alkaline agents such as aOH and KOH, HCl and H ₂ SO ₄
In a liquid phase system adjusted to be alkaline or acidic, particularly alkaline by using an acidic agent such as, the oxidizing power by peroxide or ozone becomes strong. The oxidizing power of peroxide or ozone becomes stronger as its concentration in the liquid phase system becomes higher and as the temperature becomes higher, but from the viewpoint of workability, anticorrosion treatment is performed at a temperature lower than the boiling point of the solvent forming the liquid phase system. Preferably.

The method of manufacturing the corrosion-resistant metal member according to the present invention has been described above. However, in the present invention, the corrosion-resistant metal member may be further formed into a predetermined shape depending on the intended use. When the obtained corrosion-resistant metal member is used as a fuel cell separator, a fuel gas supply port, a passage and an exhaust port containing H ₂ or an oxidant gas supply port, a passage and an exhaust port containing O ₂ etc. To process. Such forming process can be performed at any stage in the method for producing a corrosion-resistant metal member according to the present invention, in terms of corrosion resistance, durability and productivity, after compression processing, before anticorrosion treatment, or after anticorrosion treatment. It is preferable to carry out.

The corrosion-resistant metal member according to the present invention is obtained by the above-described method for producing a corrosion-resistant metal member according to the present invention, one of the representative examples of which is a fuel cell separator, particularly a solid polymer electrolyte membrane in the center. Is a separator for sandwiching both electrodes sandwiching the electrode from the outside, that is, a separator for a solid polymer electrolyte fuel cell.

[0013]

1 to 4 are partial cross-sectional views schematically showing the steps obtained in each step of the method for producing a corrosion-resistant metal member according to the present invention. Among these, FIG. 1 is a plate-shaped metal base material with metal thin film layers formed on both sides, FIG. 2 is a compression-processed one of FIG. 1, and FIG.
FIG. 4 shows a product obtained by forming a continuous mountain-valley shape, and FIG. 4 shows the product shown in FIG. 3 subjected to anticorrosion treatment. Therefore, FIGS. 1 to 4 show the procedure in the method for producing the corrosion-resistant metal member according to the present invention in the order of the drawing numbers, and FIG. 4 is also a partial sectional view schematically showing the corrosion-resistant metal member according to the present invention. Has become.

In FIG. 1, when the noble metal thin film layers 21 and 31 are formed on both surfaces of the metal base material 11 by plating, as a result, the noble metal thin film layers 21 and 31 have many pinholes 41, 42, ...・ 51, 52 ・ ・ are formed. In FIG. 2, when the one shown in FIG. 1 is compressed by, for example, a rolling roller, the metal base material 11 is compressed to become the metal base material 11a, and the noble metal thin film layers 21 and 31 are subjected to compression work.
31a. Noble metal thin film layers 21 and 3 by compression processing
No. 1 becomes noble metal thin film layers 21a and 31a, which strongly adheres to the metal base material 11a and is densified, and in addition, a large number of large and small pinholes 41, 42, ... 51 formed in the noble metal thin film layers 21 and 31. , 52 ..., A small number of small pinholes 42a, ... 51a ,.

In FIG. 3, when the one shown in FIG. 2 is formed into a continuous ridge / valley shape, the metal base material 11a becomes a continuous ridge / valley metal base material 11b, and similarly, the precious metal thin film layers 21a and 31a also have a continuous ridge / valley shape. Of the noble metal thin film layers 21b and 31b. The pinholes 42a, ... 51a, ... Remaining on the noble metal thin film layers 21a, 31a become the pinholes 42a, 45a, ... 51a, 54a .. Therefore, the metal base material 11b is exposed at these pinholes 42a, 45a, ... 51a, 54a ,.

In FIG. 4, the metal base material exposed at the pinholes 42a, 45a, ... 51a, 54a .. Oxide 61,6 on exposed part of 11b
2, ... 71, 72 are formed. Although illustration of the whole is omitted, FIG. 4 shows a part of a fuel cell separator as a corrosion-resistant metal member according to the present invention, and a plurality of valleys of the noble metal thin film layer 21b have their front or rear ends. Part is connected so as to be in series as a whole, and there is an air supply port in the valley at the end on the right side, and an exhaust port is further provided in the valley at the end on the left side. In the state where the peaks of the noble metal thin film layer 21b are in close contact with the electrodes, the fuel gas containing, for example, H ₂ flows through the path of the air supply port → the trough part of the serial communication → the exhaust port.

[0017]

Examples Test Category 1 (Production of Corrosion-Resistant Metal Member) Example 1 First, an Au thin film layer having a thickness of 50 nm was formed on both sides of a metal plate made of SUS304L having a thickness of 1 mm by plating.
Next, what formed the Au thin film layer was compression processed at a compression rate of 15% using a rolling roller. The compressed product was subjected to a molding process for forming a supply port, a passage and an exhaust port for a fuel gas containing H ₂ , and finally, the molded product was immersed in a 34 wt% H ₂ O ₂ aqueous solution. 60 at 25 ° C
Anticorrosion treatment was performed for a minute to produce a corrosion resistant metal member used as a fuel cell separator.

Examples 2 to 27 One or more selected from the material of the metal plate material, the means for forming the noble metal thin film layer, the thickness and material, the compressibility, and the anticorrosion treatment condition are changed as shown in Table 1, Otherwise in the same manner as in Example 1, a corrosion resistant metal member was manufactured. Table 1 shows the manufacturing conditions of the corrosion-resistant metal members of the respective examples manufactured as described above.

Comparative Example 1 A 50-nm-thick Au thin film layer was formed on both surfaces of a 1 mm-thick SUS304L metal plate material by plating, and the Au thin film layer was formed, and the same forming process as in Example 1 was performed. ,
A corrosion resistant metal member used as a fuel cell separator was manufactured. Therefore, in this example, compression processing and anticorrosion processing are not performed.

Comparative Examples 2 and 3 Corrosion resistant metal members were produced in the same manner as in Comparative Example 1 except that the thickness of the Au thin film layer was changed as shown in Table 2.

Comparative Example 4 First, an Au thin film layer having a thickness of 50 nm was formed on both surfaces of a metal plate made of SUS304L having a thickness of 1 mm by plating.
Next, after the Au thin film layer was formed, it was compressed by a roller pressure at a compression rate of 30%, and then the same molding process as in Example 1 was performed to manufacture a corrosion-resistant metal member used as a fuel cell separator. Therefore, in this example, anticorrosion treatment is not performed.

Comparative Example 5 A corrosion resistant metal member was produced in the same manner as in Comparative Example 4 except that the compressibility of the Au thin film layer was changed as shown in Table 2.

Comparative Example 6 First, an Au thin film layer having a thickness of 50 nm was formed on both surfaces of a metal plate made of SUS304L having a thickness of 1 mm by plating.
Then, after forming the Au thin film layer by the same forming process as in Example 1, the Au thin film layer was immersed in a 34 wt% H ₂ O ₂ aqueous solution and subjected to anticorrosion treatment at 25 ° C. for 60 minutes to prepare a fuel cell. A corrosion-resistant metal member used as a separator for a vehicle was manufactured. Therefore, in this example, compression processing is not performed.

Comparative Example 7 A corrosion resistant metal member was manufactured in the same manner as in Comparative Example 6 except that the anticorrosion treatment conditions were changed as shown in Table 2.

Comparative Example 8 First, an Au thin film layer having a thickness of 50 nm was formed on both surfaces of a metal plate material made of SUS304L having a thickness of 1 mm by plating.
Next, what formed the Au thin film layer was compression-processed by pressing the roller at a compression rate of 50%. The compression-processed product was subjected to the same molding process as in Example 1, and finally, the molded product was immersed in a 60 wt% HNO ₃ aqueous solution and subjected to anticorrosion treatment at 25 ° C. for 60 minutes to prepare a fuel cell separator. A corrosion-resistant metal member used as was produced.

Comparative Examples 9 to 13 Corrosion resistant metal members were manufactured in the same manner as in Comparative Example 8 except that the anticorrosion treatment conditions were changed as shown in Table 2. Table 2 shows the manufacturing conditions of the corrosion-resistant metal member of each comparative example manufactured as described above.

[0027]

[Table 1]

[0028]

[Table 2]

In Tables 1 and 2, * 1: material of the metal base material * 2: type of peroxide T ₀ : thickness before compression processing T ₁ : thickness after compression processing * 3: weight% A −1: H ₂ O ₂ A-2: BaO ₂ A-3: Na ₂ O ₂ A-4: (NH ₄ ) ₂ S ₂ O ₈ A-5: K ₄ P ₂ O ₈ A-6: Na _{2 CO 4 a-7: NaBO 3} a-8: CO (NH 2) 2 · H 2 O 2 a-9: O 3 a-1: HNO 3 B-1: pH2 of aqueous _H 2 SO ₄ B-2: pH 10 NaOH aqueous solution

Test Category 2 (Evaluation of Corrosion-Resistant Metal Member Produced) Corrosion resistance and contact electric resistance of the corrosion-resistant metal member of each example produced in Test Category 1 were determined as follows, and the results are shown in Table 3 for Examples. Table 4 shows the comparative examples. Corrosion resistance It was performed as follows according to JIS-H8620. Add 1 L of 63% HNO ₃ aqueous solution to the bottom of the desiccator,
A test piece cut from the corrosion-resistant metal member of each example was hung at a position 5 cm above the liquid surface, and the desiccator was covered with a lid. And 6
After aerating the 3% HNO ₃ aqueous solution for 2 hours, the test piece was taken out from the desiccator, and the test piece was magnified 1 × under an optical microscope at a magnification of 10 ×.
The number of pinholes per cm ² was counted (pieces / cm ² ) and used as an index of corrosion resistance. Contact electric resistance Both sides of the test piece cut out from the corrosion-resistant metal member of each example were sandwiched by carbon paper, and the load was 2.5 MPa and the applied current was 1
The voltage when flowing 00 mA was measured to determine the contact electric resistance (mΩ · cm ² ).

[0031]

[Table 3]

[0032]

[Table 4]

As is clear from the results shown in Tables 3 and 4, each Example had a sufficiently low contact electric resistance as compared with each Comparative Example, the number of pinholes after the corrosion resistance test was extremely small, and the gold Since film peeling does not occur, it has a high degree of corrosion resistance. Therefore, the corrosion-resistant metal member according to the present invention is particularly useful as a fuel cell separator.

[0034]

As is apparent from the above, the present invention described above can provide a corrosion-resistant metal member having a high degree of corrosion resistance by a simple manufacturing means without being limited by the material of the metal used as the base material. There is also a side effect that the exposed part of the end can be protected at the same time.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view schematically showing a plate-shaped metal base material having metal thin film layers formed on both surfaces thereof in the method for producing a corrosion-resistant metal member according to the present invention.

2 is a partial cross-sectional view schematically showing a compression-processed product of FIG. 1 in the method for manufacturing a corrosion-resistant metal member according to the present invention.

FIG. 3 is a partial cross-sectional view schematically showing a continuous ridge-valley shape of the one shown in FIG. 2 in the method for producing a corrosion-resistant metal member according to the present invention.

FIG. 4 is a partial cross-sectional view schematically showing an anticorrosion treatment of that of FIG. 3 in the method for producing a corrosion-resistant metal member according to the present invention.

[Explanation of symbols]

11, 11a, 11b ... Metal base material 21, 31,
21a, 21b, 31a, 31b ... Noble metal thin film layer, 4
1, 42, 51, 52, 42a, 45a, 51a, 54
b .. Pinhole, 61, 62, 71, 72 .. Oxide

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroaki Yoshida             2-30, Daido-cho, Minami-ku, Nagoya-shi, Aichi             Daido Steel Co., Ltd. Technology Development Laboratory (72) Inventor Masaki Shinkawa             2-30, Daido-cho, Minami-ku, Nagoya-shi, Aichi             Daido Steel Co., Ltd. Technology Development Laboratory F-term (reference) 4K026 AA01 AA02 AA06 AA08 AA09                       BA08 BB08 CA16 CA35 DA03                 4K044 AA02 AA06 AB02 BA08 BB01                       BC02 CA13 CA14 CA15 CA18                       CA53 CA67                 5H026 BB02 BB10 CX00 CX04 EE02                       HH03

Claims (13)

[Claims] 1. A noble metal thin film layer is formed on a required portion of the surface of a metal base material, the noble metal thin film layer is subjected to compression processing, and then subjected to anticorrosion treatment in a liquid phase system containing peroxide or ozone. A method of manufacturing a corrosion-resistant metal member. 2. The method for producing a corrosion-resistant metal member according to claim 1, wherein a metal plate material is used as the metal base material, and the noble metal thin film layer is formed on at least one surface of the metal plate. 3. The method for producing a corrosion-resistant metal member according to claim 2, further comprising forming into a predetermined shape after compression processing and before or after anticorrosion treatment. 4. Fe, Ni, T as a metal base material
Use of one metal selected from i, Cu and Al or an alloy based on the one metal.
A method for producing a corrosion-resistant metal member according to any one of the items. 5. A noble metal thin film layer is formed of Au, Pt, Pd, A
The method for producing a corrosion-resistant metal member according to any one of claims 1 to 4, wherein the corrosion-resistant metal member is formed of one metal selected from g, Rh, and Ru or an alloy based on the one metal. 6. The method for producing a corrosion-resistant metal member according to claim 1, wherein the noble metal thin film layer is formed by at least one means selected from plating, screen printing, PVD treatment and CVD treatment. 7. The method for producing a corrosion-resistant metal member according to claim 1, wherein a noble metal thin film layer having a thickness of 0.1 to 100 nm is formed. 8. The method for producing a corrosion-resistant metal member according to claim 1, wherein the noble metal thin film layer is compression-processed to have a compression ratio of 5% or more. 9. The method for producing a corrosion-resistant metal member according to claim 1, wherein the anticorrosion treatment is carried out in an acidic or alkaline liquid phase system containing a peroxide or ozone. 10. The method for producing a corrosion-resistant metal member according to claim 1, wherein hydrogen peroxide is used as the peroxide. 11. The method for producing a corrosion-resistant metal member according to claim 1, wherein the anticorrosion treatment is performed at a temperature lower than the boiling point of the solvent forming the liquid phase system. 12. A corrosion-resistant metal member obtained by the method for producing a corrosion-resistant metal member according to any one of claims 1 to 11. 13. A separator for a fuel cell.
The corrosion-resistant metal member according to 2.