JP4575007B2 - Method for producing conductive material-containing stainless steel separator - Google Patents

Description

  The present invention relates to a method for producing a conductive material-containing stainless steel separator, and more particularly to a method for producing a conductive material-containing stainless steel separator in which a separator is made of a stainless steel material in which a granular conductive material is contained in a stainless steel base material.

  A solid polymer electrolyte fuel cell has a structure in which a desired output is obtained by stacking a plurality of fuel cells. For this reason, as a separator for partitioning each fuel battery cell, a metal material that is advantageous in terms of strength against pressure applied at the time of stacking and downsizing after stacking is promising as compared with a resin material.

As a fuel cell employing such a metal separator, a fuel cell provided with a stainless steel separator is known (see, for example, Patent Document 1 and Patent Document 2).
Japanese Patent Laid-Open No. 8-180883 (page 14, FIG. 3) JP 2000-164228 (3rd page, FIG. 9)

In Patent Document 1, a membrane electrode assembly is formed by disposing electrode layers on both sides of a solid polymer electrolyte membrane, the membrane electrode assembly is sandwiched between, for example, stainless steel separators, and the edges of the separator are sealed. A fuel cell unit sealed with a body is shown.
Patent Document 2 discloses a fuel in which an anode electrode and a cathode electrode are arranged on both sides of a solid polymer membrane to form a membrane electrode assembly, and the membrane electrode assembly is sandwiched between separators made of, for example, a stainless steel material. A battery cell is shown.

In the techniques of Patent Document 1 and Patent Document 2 described above, a stainless steel material used as a separator material has a predetermined plate thickness.
For this reason, for example, when cold rolling is performed on a stainless steel material, the oxide and the intermetallic compound contained in the stainless steel plate are crushed on the surface layer portion of the stainless steel material to reduce the particle size. There is a risk that a deteriorated layer made of material or the like may be formed.

Since this deteriorated layer has poor conductivity, it is necessary to reduce the electrical contact resistance of the separator by removing the deteriorated layer from the stainless steel plate.
Then, the manufacturing method of the separator which provided the process of removing such a deteriorated layer of stainless steel material was considered. This technique is described below.

FIG. 20 is a diagram for explaining a manufacturing process of a conventional metal separator.
In the manufacturing process 1, the metal material 100 used as the material of the separator is rolled before being press-formed into a predetermined shape.
When the metal material 100 is rolled, an altered layer 101 is formed on the surface layer of the metal material 100.

In the manufacturing process 2, the above-described deteriorated layer 101 is removed by an etching process.
In the manufacturing process 3, in order to prevent the corrosion of the surface of the metal material 100, the 1st passivation process is implemented and the 1st passivation film 102 is formed.
In the manufacturing process 4, an etching process is performed to cue up the granular conductive materials 103 (... indicates a plurality, the same applies hereinafter) contained in the metal material 100.

In the manufacturing process 5, after the cueing of the conductive materials 103, the second passivation process is performed so that the surface of the metal material 100 is not corroded, and the second passivation film 105 is formed.
This completes the manufacture of the separator.

FIG. 21 is a view showing a state in which a conventional metal separator is brought into contact with a membrane electrode assembly.
The conductive material 103 is a granular material. For this reason, only the top parts 103b ... of the parts 103a ... headed from the surface of the metal material 100 come into contact with the membrane electrode assembly 106 (so-called point contact).
In addition, the top portions 103b of the conductive materials 103 are not flush with each other. Therefore, it is difficult to make all the top portions 103b of the conductive materials 103 contact the membrane electrode assembly 106 satisfactorily.

For this reason, there is a possibility that a sufficient contact area of the conductors 103 to the membrane electrode assembly 106 cannot be ensured.
When the contact area of the conductors 103 to the membrane electrode assembly 106 cannot be sufficiently secured, it is difficult to reduce the contact resistance, which hinders the improvement of the power generation performance of the fuel cell.
For this reason, the practical application of the manufacturing method which can increase the contact area of the conductors 103 ... with respect to the membrane electrode assembly 106 has been desired.

  This invention makes it a subject to provide the manufacturing method of the separator made from a conductor containing stainless steel which can increase the contact area of the conductor with respect to a membrane electrode assembly.

The invention according to claim 1 is a fuel comprising a stainless steel material in which a conductive material made of granular chromium boride or carbide is contained in a stainless steel base material, and having a convex portion in contact with one surface of the membrane electrode assembly a method of manufacturing a battery separator, the rolling process to obtain a preparation step of preparing a stainless steel material which contains a conductive material of the granular stainless base material, the rolled material by rolling the stainless steel to a predetermined thickness When, the rolled material by press-forming, a forming step that form a convex portion in contact with one surface of the membrane electrode assembly in the rolling member, the convex of the rolled material forming the convex portion A surface layer removing step of removing only the surface layer of the shaped portion, and grinding the surface of the rolled material from which the surface layer has been removed by pressing a grindstone to expose the conductive material on the surface of the stainless steel base material. Surface A flattening step for flattening the exposed surface of the fine the conductive material is subjected to solvent grinding the surface of the rolled material, by dissolving the stainless base material while maintaining the non-dissolving the conductive material in said solvent, said stainless a melting step of preform that Hekomase than the exposed surface of the conductive material, characterized by comprising the.

In the surface layer removing step, the surface layer of the rolled material is removed, and the conductive material is kept embedded in the stainless steel base material. In this state, the exposed surface of the conductive material is ground flat in the planarization step.
By grinding the exposed surface of the conductive material flat, the contact area of the conductive material with respect to the contacted member is increased.
Here, since grinding is performed with the conductive material embedded in the stainless steel base material, the conductive material is held by the stainless steel base material even if a grinding force is applied to the conductive material. Therefore, there is no possibility that the conductive material falls off from the stainless steel base material.

By grinding the surface from which the surface layer of the rolled material is removed by pressing a grindstone, the conductive material can be exposed on the surface of the stainless steel base material, and the surface of the stainless steel base material and the exposed surface of the conductive material can be flattened.
After the exposed surface of the conductive material is ground flat, in the melting step, a solvent is applied to the flat ground surface, and the flat ground surface is melted (melted) with the solvent.
By dissolving the flat ground surface with a solvent, the stainless steel base material is dissolved while keeping the conductive material undissolved.
By dissolving the stainless steel base material, the stainless steel base material is recessed from the exposed surface of the conductive material, and the exposed surface of the conductive material is reliably brought into contact with the contacted member.
Here, in the fuel cell, a separator is interposed between a plurality of membrane electrode assemblies, and a plurality of membrane electrode assemblies and separators are unitized in this state.
The separator includes a plurality of flow path grooves on the surface in order to form a gas flow path and a water flow path in a state where the separator is in contact with the membrane electrode assembly. By providing the channel grooves on the surface, the surface of the separator becomes uneven.
Therefore, when the separator is interposed between the membrane electrode assemblies, only the convex portion of the surface of the separator contacts the membrane electrode assembly.
Therefore, the contact resistance of only the convex portion of the separator may be reduced.
Therefore, it was decided to press the stainless steel material into the separator before the surface layer removing step. After the stainless steel material is press-molded into the separator, the surface layer removal step, the planarization step, and the dissolution step may be performed only on the convex portion that is the contact portion of the separator.
Therefore, it is not necessary to treat the entire surface of the separator in each step.

  According to a second aspect of the present invention, the surface layer removing step and the flattening step are performed simultaneously.

  By simultaneously performing the process of exposing the conductive material in the surface layer removing process and the process of flattening the exposed surface of the conductive material in the planarization process, the exposure process and the planarization process can be simplified.

  According to a third aspect of the present invention, a stainless steel film removing step for removing the stainless steel film from the exposed surface of the flattened conductive material is added between the flattening step and the dissolving step.

  Here, the flattening step is usually performed by a relatively rough process in consideration of the processing time and the like. If the stainless steel base material and the conductive material are ground at the same time by rough processing, the exposed surface of the conductive material may be covered with the ground stainless steel base material film (hereinafter referred to as “stainless steel film”).

Therefore, in claim 3, a stainless steel film removing step for removing the stainless steel film from the exposed surface of the flattened conductive material is added between the flattening step and the dissolving step.
By removing the stainless steel film from the exposed surface of the conductive material, the exposed surface of the conductive material can be reliably brought into contact with the contacted member.

  According to a fourth aspect of the present invention, in the surface layer removing step and the flattening step, these steps are performed with a grindstone in which a rotation axis is arranged perpendicular to the stainless steel material.

The grindstone is provided at the lower end of the rotating shaft by arranging the rotating shaft of the grindstone perpendicular to the stainless steel material.
The cutting blade surface of the grindstone is made flat, and the flat cutting blade surface is arranged in parallel to the separator 13 so that the entire cutting blade surface of the grindstone is uniformly pressed against the stainless steel material.
Therefore, the stainless steel material can be uniformly ground with the grindstone, and the processing accuracy of the grindstone can be further enhanced.

In the invention according to claim 1, there is an advantage that the contact resistance of the conductive material with respect to the contacted member can be reduced by increasing the contact area of the conductive material and making sure that the exposed surface of the conductive material is in contact with the contacted member. is there.
Moreover, in the invention which concerns on Claim 1, it becomes possible to grind only the convex part which is a contact part of a separator by a surface layer removal process or a planarization process, and to melt-process only a convex part. Since it is not necessary to treat the entire surface of the separator, there are advantages that the treatment time can be shortened and wear due to wear of the grinding wheel can be reduced.
Furthermore, in the invention which concerns on Claim 1, there exists an advantage that the exposed surface of an electrically conductive substance can be made flat by grind | pulverizing the surface which removed the surface layer of the rolling material, pressing a grindstone.

  The invention according to claim 2 is advantageous in that the surface layer removal process and the planarization process are simultaneously performed, thereby simplifying the exposure process and the planarization process of the conductive material, and realizing the work efficiency.

  In the invention according to claim 3, by removing the stainless steel film from the exposed surface of the conductive material, and reliably contacting the exposed surface of the conductive material with the contacted member, the contact resistance of the conductive material with respect to the contacted member is further increased. There is an advantage that it can be lowered.

  In the invention which concerns on Claim 4, it becomes possible to grind a stainless steel material uniformly with a grindstone, and to raise the processing precision of a grindstone further. There is an advantage that the processing efficiency can be increased by further increasing the processing accuracy of the grindstone.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a cross-sectional view showing a fuel cell of a fuel cell.
The fuel cell 10 is a unit in which a large number of fuel cells (that is, unit fuel cells) 11 are stacked.
The fuel battery cell 11 is provided with stainless steel separators 13 and 13 on both surfaces 12a and 12b of a membrane electrode assembly 12 (hereinafter referred to as “MEA (Membrane Electrode Assembly)”).

The MEA 12 is provided with positive and negative electrode layers 15 and 16 on both sides of the electrolyte membrane 14, a positive electrode side diffusion layer 17 is provided outside the positive electrode layer 15, and a negative electrode side diffusion layer 18 is provided outside the negative electrode layer 16. It is a thing.
The positive electrode layer 15 and the positive electrode side diffusion layer 17 may be collectively referred to as a positive electrode layer, and the negative electrode layer 16 and the negative electrode side diffusion layer 18 may be collectively referred to as a positive electrode layer.

The stainless steel separator 13 is obtained by rolling a stainless steel material 22 containing a conductive material 21 (see FIG. 3), and pressing the rolled material 23 to form both surfaces 13a and 13b in an uneven shape.
By forming the both surfaces 13a and 13b of the separator 13 in a concavo-convex shape, the both surfaces 13a and 13b are provided with a plurality of grooves 24.
By bringing the separator 13 into contact with both surfaces 12a and 12b of the MEA 12, the plurality of grooves 24 are closed by the both surfaces 12a and 12b of the MEA 12, and a flow path 25 for guiding gas and a flow path 25 for guiding water are formed. Form.

As for this separator 13, convex part 26 ... of both surfaces 13a and 13b contacts both surfaces 12a and 12b of MEA12.
Therefore, it is preferable to reduce the contact resistance of the convex portions 26 of the separator 12.
The conductive material 21 increases the conductivity of the separator 12. For example, boride (boride) is known as the conductive material 21, and specific examples of the boride include chromium boride (Cr ₂ B).
Hereinafter, a manufacturing method for reducing the contact resistance of the convex portions 26 of the separator 13 will be described.

FIG. 2 is a flowchart for explaining a first embodiment of the method for producing a conductive material-containing stainless steel separator according to the present invention, and STxx in the figure indicates a step number.
ST10: In the preparation step, a stainless steel material in which a granular base material is contained in a stainless steel base material is prepared.
ST11: In the rolling process, the stainless steel material is rolled to a predetermined thickness.

ST12: In the forming step, the rolled material is press-formed into a separator.
ST13: In the surface layer removing step, the surface layer of the separator is removed.
ST14: In the planarization step, the surface from which the surface layer has been removed is ground to flatten the surface of the stainless steel base material and the exposed surface of the conductive material.

ST15: In the stainless steel film removing step, the stainless steel film is removed from the exposed surface of the flattened conductive material.
ST16: In the melting step, the stainless steel base material is dissolved by applying a solvent to the surface from which the stainless steel film has been removed.
This solvent dissolves (cuts) the stainless steel base material and does not dissolve the conductive material, that is, keeps the conductive material undissolved.
Thereafter, a passive film is formed on the surface of the stainless steel base material.
Hereinafter, the contents of ST10 to ST16 will be described in detail with reference to FIGS.

FIGS. 3A and 3B are diagrams for explaining a process of rolling a material in the manufacturing method according to the first embodiment. ST10 is described with reference to (a) and ST11 with reference to (b).
In (a), a stainless steel material 22 is prepared as a material for the separator 13 shown in FIG. The stainless steel material 22 is a stainless steel base material 27 containing a granular conductive material 21.

In (b), a rolled material is obtained by cold-rolling (rolling) the stainless steel material 22 to a predetermined thickness t1 with upper and lower rolls 31, 32.
During the rolling, the conductive materials 21 of the surface layers 33 and 33 of the stainless steel material 22 may be crushed due to the rolling.
For this reason, in the surface layers 34 and 34 of the rolled material 23, there are conductors 21.
For this reason, the surface layers 34 and 34 of the rolled material 23 are often referred to as “rolling affected part” or “rolled layer”.

4 (a) to 4 (c) are diagrams illustrating a process of press-molding a separator in the manufacturing method according to the first embodiment, and ST12 will be described.
In (a), the rolled material 23 is set in a press molding machine 35, and the movable mold 36 of the press molding machine 35 is moved and clamped.
The rolled material 23 is press-formed by the movable die 36 and the fixed die 37 by clamping.

In (b), the stainless steel separator 13 is obtained by press-molding the rolled material 23.
By forming the separator 13 in a concavo-convex shape, the concave portion is used as a groove 24 for guiding gas and water, and the convex portion is a convex portion that contacts both surfaces 12a and 12b (see FIG. 1) of the MEA 12. Suppose that it is a part 26 ... (namely, contact part).

Since it is only necessary to reduce the contact resistance of only the convex portions 26...
Therefore, in the surface layer removing step, the flattening step, the stainless steel film removing step, and the dissolving step described with reference to FIGS.
This makes it possible to shorten the processing time and reduce wear due to wear of the grinding wheel.

  (C) is a plan view of the separator 13, formed with grooves 24 for guiding gas and water on one surface 13 a of the separator 13, and in contact with both surfaces 12 a and 12 b (see FIG. 1) of the MEA 12. The state which formed convex part 26 ... is shown.

FIGS. 5A and 5B are diagrams for explaining the process of setting the separator in the grinding machine in the manufacturing method of the first embodiment, and the first half of ST13 will be explained. FIG. 5A shows an enlarged view of part 5 (a) of FIG. 4B.
In (a), the stainless steel separator 13 contains the conductive materials 21 in the stainless steel base material 27, and the surface layer 34 includes the small conductive materials 21a crushed during rolling.
Hereinafter, in order to facilitate understanding, reference will be made to the small crushed conductive material with reference numeral 21a.
If the conductive material 21a is small, the contact area that contacts the MEA 12 (see FIG. 1) becomes small, and it is difficult to keep the conductivity of the separator 13 good.
Here, the thickness t2 of the surface layer 34 including the small crushed conductors 21a is 3 μm.

In (b), the separator 13 is set on the surface plate 42 of the polishing machine 41, and the surface plate 42 is rotated around the rotation shaft 44 of the polishing machine 41 as indicated by the arrow b while dripping the slurry 43 onto the separator 13. To do.
While rotating the platen 42, the grindstone 46 is rotated by the rotating shaft 45 as indicated by the arrow c, so that the surface layer 34 of the convex portions 26 (see FIG. 5 (a)) formed on the separator 13. Grind.
As shown in (a), the thickness t2 of the surface layer 34 is 3 μm. Therefore, the grinding allowance by the grindstone 46 is made larger than 3 μm.

FIGS. 6A and 6B are diagrams for explaining the process of removing the surface layer in the manufacturing method of the first embodiment, and the latter half of ST13 will be described.
In (a), the separator 13 is fixed to the surface plate 42 by the bonding means 38 and 38.
As the bonding means 38, for example, a double-sided adhesive tape having an adhesive on both sides of the tape is used.
The rotating shaft 45 of the grindstone 46 is disposed perpendicular to the separator 13, and the grindstone 46 is provided at the lower end of the rotating shaft 45.

The cutting blade surface 46 a of the grindstone 46 is made flat, and this flat cutting blade surface 46 a is arranged in parallel to the separator 13.
Therefore, the entire cutting edge surface 46a of the grindstone 46 can be uniformly pressed against the convex portion 26 of the separator 13 as indicated by the arrow d.

Here, the grinding conditions in the surface layer removing step are as follows.
As the grindstone 46, a medium-sized surface grinding grindstone with GC (green silicon carbide) abrasive grains and a particle size of 60 mesh (number) was used.
The rotational speed of the grindstone 46 was 2800 rpm, and the grinding time was 3 minutes.
While supplying water to the surface layer 34, the surface layer 34 was ground by t 2, that is, 3 μm by the grindstone 46.

In (b), the surface layer 34 is removed from the convex part 26 by grinding the convex part 26 of the separator 13 with the cutting edge surface 46a (refer FIG. 6A) of the grindstone 46 by the said grinding conditions.
By removing the surface layer 34, the surface of the convex portion 26 is used as a grinding surface 47.
In the convex portion 26, the conductive material 21 is kept embedded in the stainless steel base material 27.
By uniformly pressing the entire cutting blade surface 46a of the grindstone 46 against the convex portion 26 of the separator 13, the convex portion 26 of the separator 13 is uniformly ground by the cutting blade surface 46a of the grindstone 46, and the cutting blade surface 46a of the grindstone 46 is obtained. The processing accuracy can be further increased.

FIGS. 7A to 7C are diagrams illustrating a process of flattening the exposed surface of the conductive material in the manufacturing method of the first embodiment, and ST14 will be described.
In (a), the separator 13 is fixed to the surface plate 52 of the polishing machine 51 with bonding means (for example, double-sided adhesive tape) 38, 38.
The rotating shaft 54 of the grindstone 53 is disposed perpendicular to the separator 13, and the grindstone 53 is provided at the lower end of the rotating shaft 54.

The cutting blade surface 53 a of the grindstone 53 is made flat, and the flat cutting blade surface 53 a is arranged in parallel to the separator 13.
Therefore, the entire cutting edge surface 53a of the grindstone 53 can be uniformly pressed against the grinding surface 47 of the separator 13 as indicated by an arrow e.
In this state, the surface plate 52 is rotated in the same manner as the surface plate 42 (see FIG. 5B), coolant (cooling liquid) 55 is dropped onto the separator 13, and the convex portion 26 is cut by the cutting edge surface 53 a of the grindstone 53. The grinding surface 47 is ground.

Here, the grinding conditions in the flattening step are as follows.
As the grindstone 53, an extremely fine surface grinding grindstone with GC (green silicon carbide) abrasive grains and a particle size of 600 mesh (number) was used.
As the abrasive grains of the grindstone 53, those harder than the stainless steel base material 27 and the conductive material 21 were used, and as the bonds for bonding the abrasive grains, relatively soft ones were used.

The rotational speed of the grindstone 53 was 2800 rpm, and the grinding time was 5 minutes 44 seconds.
The ground surface 47 was ground by the grindstone 53 for t3, that is, 10 μm.
By using a relatively soft bond for the grindstone 53, the exposed surface 21b of the conductive material 21 is prevented from being scratched by the abrasive grains of the grindstone 53.
Thereby, the surface roughness of the exposed surfaces 21b of the conductive materials 21 is suitably maintained.

In (b), the grinding surface 47 is ground with the cutting edge surface 53a of the grindstone 53 (see FIG. 7A). The grinding allowance t3 is 10 μm.
At this time, the entire cutting edge surface 53 a of the grindstone 53 is uniformly pressed against the grinding surface 47 of the separator 13, so that the grinding surface 47 of the separator 13 is uniformly ground by the cutting edge surface 53 a of the grindstone 53. The processing accuracy of the blade surface 53a can be further increased.
The grinding allowance t3 for this flattening is 10 μm as described above.
The reason why the grinding allowance t3 is set to 10 μm is that the variation in the height of the convex portion 26 is considered to be about 10 μm due to the distortion generated in the press molding of FIG.

  The grinding surface 47 is ground by 10 μm with the cutting edge surface 53a (see FIG. 7A) of the grindstone 53, so that the surface 27a (see FIG. 7C) of the stainless steel base material 27 and the exposed surface 21b of the conductive material 21 are obtained. (See FIG. 7C) is flattened.

Here, the separator 13 is kept in a state where the surface layer 34 (see FIG. 5A) is removed, and the conductive materials 21 are embedded in the stainless steel base material 27.
As a result, the exposed surfaces 21b of the conductive materials 21 are flatly ground by the cutting blade surface 53a of the grindstone 53 in a state where the conductive materials 21 are embedded in the stainless steel base material 27.
Therefore, even if the grinding force of the grindstone 53 is applied to the conductive materials 21, the conductive materials 21 can be held by the stainless steel base material 27. Therefore, there is no possibility that the conductive materials 21 are dropped from the stainless steel base material 27.

By the way, as a method of flattening the exposed surface 21b of the conductive material 21, the conductive material 21 is projected from the stainless steel base material 27, and then the projected conductive material 21 is ground by the cutting edge surface 53a of the grindstone 53. It is also possible to do.
However, when the conductive materials 21 are projected from the stainless steel base material 27, the embedded portion of the conductive materials 21 with respect to the stainless steel base material 27 is reduced.

For this reason, when the conductive materials 21 projected from the stainless steel base material 27 are ground by the cutting blade surface 53a of the grindstone 53, it is difficult to sufficiently support the conductive materials 21 by the stainless steel base material 27.
Therefore, there is a possibility that the conductive materials 21 are dropped from the stainless steel base material 27 by the cutting force of the grindstone 53 applied to the conductive materials 21.
Therefore, in the flattening step, when the exposed surface 21b of the conductive material 21 is ground flat, the conductive material 21 is ground while being embedded in the stainless steel base material 27 as described above.

In (c), the flattening step is usually performed by a relatively rough process in consideration of the processing time and the like. When the stainless steel base material 27 and the conductive material 21 are simultaneously grounded by rough machining, the exposed surface of the conductive material 21 is formed by a film 28 of the ground stainless steel base material 27 (hereinafter referred to as “stainless film 28”). 21b ... may be covered.
Here, the film thickness t4 of the stainless steel film 28 is 0.1 μm or less.

FIGS. 8A and 8B are diagrams for explaining a process of removing the stainless steel film in the manufacturing method of the first embodiment, and ST15 will be described.
In (a), the separator 13 is fixed to the surface plate 62 of the polishing machine 61 with bonding means (for example, double-sided adhesive tape) 38, 38.
The rotating shaft 64 of the grindstone 63 is disposed perpendicular to the separator 13, and the grindstone 63 is provided at the lower end of the rotating shaft 64.

The cutting blade surface 63 a of the grindstone 63 is made flat, and this flat cutting blade surface 63 a is arranged in parallel to the separator 13.
Therefore, the entire cutting edge surface 63a of the grindstone 63 can be uniformly pressed against the stainless steel film 28 (see also FIG. 7C) of the separator 13 as indicated by an arrow f.
In this state, the surface plate 62 is rotated in the same manner as the surface plate 42 (see FIG. 5B), the coolant 65 is dropped on the separator 13, and the stainless steel film 28 of the convex portion 26 is formed on the cutting edge surface 63 a of the grindstone 63. Grind with precision machining.

Here, the grinding conditions in the stainless steel film removing step are as follows.
As the grindstone 63, an extremely fine surface grinding grindstone with GC (green silicon carbide) abrasive grains and a particle size of 600 mesh (number) was used.
As the abrasive grains of the grindstone 63, those harder than the stainless steel base material 27 and the conductive material 21 were used, and as the bonds for bonding the abrasive grains, relatively soft ones were used.

The rotational speed of the grindstone 63 was 2800 rpm, and the grinding time was about 6 seconds.
The stainless steel films 28 were precisely processed with the grindstone 63, so that the stainless steel films 28 were ground by a film thickness t4 (see FIG. 7C), that is, 0.1 μm or less.
By using a relatively soft bond for the grindstone 63, it is possible to prevent the exposed surface 21b of the conductive material 21 from being damaged by the abrasive grains of the grindstone 63.
Thereby, the surface roughness of the exposed surfaces 21b of the conductive materials 21 is suitably maintained.

In (b), the conductive material 21 is flattened by grinding (precision machining) the stainless steel film 28... With a film thickness t4 of 0.1 μm or less on the cutting edge surface 63a (see FIG. 8A) of the grindstone 63. The stainless film 28 (see FIG. 7C) is removed from the exposed surface 21b.
By uniformly pressing the entire cutting edge surface 63a of the grindstone 63 against the stainless steel film 28, the stainless steel film 28 can be uniformly ground by the cutting edge face 63a of the grindstone 63, and the processing accuracy of the grindstone 63 can be further enhanced. .
Here, the thickness t4 of the stainless film 28 is 0.1 μm or less as shown in FIG. Therefore, the grinding allowance by the grindstone 63 is set to 0.1 μm or less in accordance with t4.

The exposed surfaces 21b of the conductive materials 21 are ground flat, and the stainless film 28 (see FIG. 7C) covering the flat exposed surfaces 21b is removed, whereby both surfaces 12a of the MEA 12 shown in FIG. , 12b increases the contact area S of the conductive material 21.
As a result, the exposed surfaces 21b of the conductive materials 21 can be suitably brought into contact with the both surfaces 12a and 12b of the MEA 12.

FIGS. 9A to 9C are diagrams illustrating a process of cueing a conductive material in the manufacturing method according to the first embodiment, and ST16 will be described.
In (a), the separator 13 is degreased with alkali, and then the separator 13 is washed (washed with water). The treatment time for alkaline degreasing is 10 minutes.

Next, the separator 13 is immersed in the solvent 48. As the solvent 48, a solution obtained by adding 20% nitric acid to 8% hydrofluoric acid (so-called nitric hydrofluoric acid) was used. The time for immersing the separator 13 in the solvent 48 is 45 seconds.
The solvent 48 is a treatment liquid that dissolves the stainless base material 27 and does not dissolve the conductive materials 21..., That is, keeps the conductive materials 21 undissolved.
Thereby, the surface 27a (see FIG. 8B) of the stainless steel base material 27 is dissolved by the solvent 48.

In (b), the surface 27a of the stainless steel base material 27 (see FIG. 8B) is melted with the solvent 48, so that the melted surface 27b of the stainless steel base material 27 is recessed from the exposed surface 21b of the conductive material 21. .
The dissolution amount at this time, that is, the cutting allowance is about 0.1 μm.
Thus, the exposed surfaces 21b of the conductive materials 21 can be cueed from the melting surface 27b of the stainless steel base material 27.

In (c), after the dissolution of the stainless steel base material 27 is completed, the separator 13 is washed in two stages (washed with water), and then subjected to alkali passivation treatment.
The processing time for the two-stage cleaning is 10 minutes. The two-step cleaning means that the first cleaning layer is prewashed and then the second cleaning is finished.

Thereby, the passive film 70 is formed on the melting surface 27b of the stainless steel base material 27 excluding the exposed surface 21b of the conductive material 21.
After the passivation film 70 is formed, the separator 13 is washed in two stages, and after the washing is completed, the separator 13 is dried. This drying time is 10 minutes.
In this state, the exposed surfaces 21b of the conductive materials 21 are cleaved from the surface of the passive film 70 by a height t5.

According to the manufacturing method of the first embodiment, the surface layer removing process of ST13, the flattening process of ST14, and the stainless steel film removing process of ST15 are ground by the grindstones 46, 53, and 63, respectively, and only the dissolving process of ST16 is solvent. 48 was used.
Thereby, the usage-amount of the solvent 48 can be suppressed to a small quantity, and the effort concerning the waste liquid treatment of the solvent 48 after use can be reduced.

Next, the effect | action of the separator manufactured with the manufacturing method of the electroconductive material containing stainless steel separator is demonstrated based on FIG.
FIGS. 10A and 10B are diagrams illustrating an example in which the separator manufactured by the manufacturing method of the first embodiment is used for a fuel cell.
In (a), separators 13 and 13 are provided on both surfaces 12a and 12b of the MEA 12, respectively.
The convex portions 26 of the separator 13 are in contact with one surface 12a of the MEA 12, and the convex portions 26 of the separator 13 are in contact with the other surface 12b of the MEA 12.

In (b), the protruding portion 26 of the separator 13 is in a state where the exposed surface 21b of the conductive material 21 is cueed from the melting surface 27b of the stainless steel base material 27 by t5 and the exposed surface 21b is reliably exposed. It is kept.
By exposing the exposed surface 21b of the conductive material 21 from the melting surface 27b of the stainless steel base material 27 by t5, the exposed surface 31b of the conductive material 21 can be reliably brought into contact with the one surface 12a of the MEA 12. it can.

In addition, by reliably exposing the exposed surfaces 21b of the conductive materials 21 ..., a large contact area S ... of the exposed surfaces 21b ... is ensured.
Here, the conductive material 21 is a substance for increasing the conductivity of the separator 13. By ensuring a large contact area S where the conductive material 21 contacts the MEA 12, the contact resistance of the separator 12 can be reduced.

Next, the manufacturing method of the electrically conductive substance containing stainless steel separator of 2nd Embodiment- 5th Embodiment and reference form is demonstrated based on FIGS. In the second to fifth embodiments and the reference embodiment , the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

Second Embodiment FIG. 11 is a flowchart for explaining a second embodiment of the method for producing a conductive material-containing stainless steel separator according to the present invention.
ST20: In the preparation step, a stainless steel material in which a granular conductive material is contained in a stainless steel base material is prepared.
ST21: In the rolling process, the stainless steel material is rolled to a predetermined thickness.
ST22: In the forming step, the rolled material is press-formed into a separator.

ST23: In the surface layer removal / flattening step, the surface layer of the separator and the exposed surface of the conductive material are flattened by removing the surface layer of the separator and grinding the surface from which the surface layer has been removed.
ST24: In the stainless steel film removing step, the stainless steel film is removed from the exposed surface of the flattened conductive material.
ST25: In the melting step, a solvent is applied to the surface from which the stainless steel film has been removed.
With this solvent, the stainless steel base material is dissolved while keeping the conductive material from being dissolved.
Thereafter, a passive film is formed on the surface of the stainless steel base material.

  In the manufacturing method of the second embodiment, in the surface layer removal / planarization step of ST23, the surface layer of the stainless steel base material and the exposed surface of the conductive material are removed by removing the surface layer of the separator and grinding the surface from which the surface layer has been removed. The other steps are the same as those of the first embodiment except that the manufacturing method of the first embodiment shown in FIG.

Here, the grinding conditions in the surface layer removal / planarization step of ST23 are as follows.
As the grindstone, the grindstone 53 (see FIG. 7A) employed in the planarization process of the first embodiment was used. That is, the grindstone 53 is a very fine surface grinding grindstone with GC (green silicon carbide) abrasive grains and a particle size of 600 mesh (number).
The rotational speed of the grindstone 53 was 2800 rpm, and the grinding time was 8 minutes.

FIG. 12 is a diagram for explaining a surface layer removal / planarization step in the manufacturing method according to the second embodiment.
In (a), the surface layer 34 exists in the convex part 26 of the separator 13 by thickness t2 (3 micrometers). The surface layer 34 is ground by t2 (3 μm) with the grindstone 53.
In (b), the surface layer 34 is ground by t2 (3 μm) to expose the grinding surface 47, and then the grinding surface 47 is continuously ground by the grindstone 53 for t3 (10 μm).
In (c), the surface layer removal / planarization step is usually performed by a relatively rough process in consideration of the processing time and the like. Therefore, similarly to the first embodiment, the exposed surfaces 21b of the conductive materials 21 may be covered with the ground film 28 of the stainless steel base material 27 (that is, the stainless steel film).
Here, the film thickness t4 of the stainless steel film 28 is 0.1 μm or less.

The stainless steel films 28 covering the exposed surfaces 21b of the conductive materials 21 are dissolved and removed in the melting step ST25.
As a result, the exposed surfaces 21b of the conductive materials 21 can be surely exposed, and the exposed surfaces 21b of the conductors 21 can be cueed from the melting surface 27b of the stainless steel base material 27.

According to the manufacturing method of the second embodiment, the same effects as those of the manufacturing method of the first embodiment can be obtained.
In addition, according to the manufacturing method of the second embodiment, the surface layer removal step and the planarization step are simultaneously performed in ST23.
Thereby, the exposure process and the planarization process can be simplified by simultaneously performing the process of exposing the conductive material in the surface layer removing process and the process of flattening the exposed surface of the conductive material in the planarization process.

Third Embodiment FIG. 13 is a flowchart for explaining a third embodiment of the method for producing a conductive material-containing stainless steel separator according to the present invention.
ST30: In the preparation step, a stainless steel material in which a granular conductive material is contained in a stainless steel base material is prepared.
ST31: In the rolling process, the stainless steel material is rolled to a predetermined thickness.
ST32: In the forming step, the rolled material is press-formed into a separator.

ST33: In the surface layer removing step, the surface layer of the separator is removed.
ST34: In the flattening step, the surface from which the surface layer has been removed is ground to flatten the surface of the stainless steel base material and the exposed surface of the conductive material.
ST35: In the melting step, a solvent is applied to the flat ground surface.
With this solvent, the stainless steel base material is dissolved while keeping the conductive material from being dissolved.
Thereafter, a passive film is formed on the surface of the stainless steel base material.

  The manufacturing method according to the third embodiment is different from the manufacturing method according to the first embodiment in that the stainless steel film removing step ST15 is omitted from the manufacturing method according to the first embodiment shown in FIG. Is the same as in the first embodiment.

Here, by omitting the stainless steel film removing step, as shown in FIG. 7C, the exposed surfaces 21b of the conductive materials 21 are made of a ground film 28 of the stainless steel base material 27 (ie, a stainless steel film). There is a risk of being covered.
However, in the melting step of ST35, as in ST16 of the first embodiment, the stainless steel base material 27 is melted with the solvent 48 and the exposed surface 21b of the conductive material 21 (see FIG. 9B) -like stainless steel. It is possible to dissolve the membrane 28.
Thereby, the stainless steel films 28 (see FIG. 7C) can be removed from the exposed surfaces 21b of the conductive materials 21.

According to the manufacturing method of the third embodiment, the same effect as that of the manufacturing method of the first embodiment can be obtained.
In addition, according to the manufacturing method of the third embodiment, the manufacturing method of the third embodiment can be simplified by omitting the step of removing the stainless steel film of ST15 from the manufacturing method of the first embodiment. it can.

Fourth Embodiment FIG. 14 is a flowchart for explaining a fourth embodiment of the method for producing a conductive material-containing stainless steel separator according to the present invention.
ST40: In the preparation step, a stainless steel material in which a granular conductive material is contained in a stainless steel base material is prepared.
ST41: In the rolling process, the stainless steel material is rolled to a predetermined thickness.
ST42: In the forming step, the rolled material is press-formed into a separator.

ST43: In the surface layer removal / planarization step, the surface layer of the stainless steel base material and the exposed surface of the conductive material are flattened by removing the surface layer of the separator and grinding the surface from which the surface layer has been removed.
ST45: In the melting step, a solvent is applied to the flat ground surface. With this solvent, the stainless steel base material is dissolved while the conductive material is not dissolved.
Thereafter, a passive film is formed on the surface of the stainless steel base material.

  In the manufacturing method of the fourth embodiment, in the surface layer removal / planarization step of ST43, the surface layer of the stainless steel base material and the exposed surface of the conductive material are removed by removing the surface layer of the separator and grinding the surface from which the surface layer has been removed. 2 and the manufacturing method of the first embodiment shown in FIG. 2 omits the step of removing the stainless steel film in ST15. Other steps are the same as those of the first embodiment except for the manufacturing method of the first embodiment. It is the same as the form.

Here, the grinding conditions in the surface layer removal / planarization process in ST43 are the same as those in the surface layer removal / planarization process in ST23 of the second embodiment, and the description of the grinding conditions is omitted.
In addition, the surface layer removal / planarization step in ST43 is the same as that in FIG. 12 describing the surface layer removal / planarization step in ST23 of the second embodiment, and the description of this step is omitted.

According to the manufacturing method of the fourth embodiment, the same effects as those of the manufacturing method of the first embodiment can be obtained.
Furthermore, according to the manufacturing method of the fourth embodiment, similarly to the manufacturing method of the second embodiment, the surface layer removal step and the planarization step are simultaneously performed in ST43.
Thereby, the exposure process and the planarization process can be simplified by simultaneously performing the process of exposing the conductive material in the surface layer removing process and the process of flattening the exposed surface of the conductive material in the planarization process.
In addition, according to the manufacturing method of the fourth embodiment, similar to the manufacturing method of the third embodiment, the step of removing the stainless steel film in ST15 is omitted from the manufacturing method of the first embodiment. The manufacturing method of the form can be simplified.

Reference Form FIG. 15 is a flowchart for explaining a reference form of the method for producing a conductive material-containing stainless steel separator according to the present invention.
ST50: In the preparation step, a stainless steel material in which a granular conductive material is contained in a stainless steel base material is prepared.
ST51: In the rolling process, the stainless steel material is rolled to a predetermined thickness.

ST52: In the surface layer removing step, the surface layer of the rolled material is removed.
ST53: In the flattening step, the surface from which the surface layer is removed is ground to flatten the surface of the rolled material 23, that is, the surface of the stainless steel base material 27 and the exposed surface 21b of the conductive material 21.

ST54: In the melting step, a solvent is applied to the obtained flat ground surface. With this solvent, the stainless steel base material is dissolved while keeping the conductive material in a flat ground surface.
Thereafter, a passive film is formed on the surface of the stainless steel base material.
Thereby, the exposed surface of the conductive material is projected from the surface of the rolled material.
ST55: In the forming step, the rolled material with the exposed surface of the conductive material protruding on the surface is press-formed on the separator.

FIG. 16 is a diagram for explaining a surface layer removing step and a planarizing step in the manufacturing method of the reference embodiment .
In (a), a surface layer 34 is present on the surface of the rolled material 23 at a thickness of t2 (3 μm). The surface layer 34 is ground by t2 (3 μm) with a grindstone 46 (see FIG. 6A).
In (b), the surface layer 34 is ground to form a ground surface 47, and this ground surface 47 is ground by t3 (10 μm) with a grindstone 53 (see FIG. 7A).
In (c), the flattening step is usually performed by a relatively rough process in consideration of the processing time and the like. Therefore, similarly to the first embodiment, the exposed surfaces 21b of the conductive materials 21 may be covered with the ground film 28 of the stainless steel base material 27 (that is, the stainless steel film).
Here, the film thickness t4 of the stainless steel film 28 is 0.1 μm or less.

FIGS. 17A and 17B are diagrams for explaining a dissolution process in the manufacturing method of the reference form .
In (a), the surface 27 a of the stainless steel base material 27 is dissolved with a solvent 48. The surface 27a (see FIG. 16 (c)) of the stainless steel base material 27 is dissolved by the solvent 48 (see FIG. 9 (a)), so that the surface 27a of the stainless steel base material 27 is exposed to the exposed surface 21b ... Make it more concave.

When the surface 27a (see FIG. 8 (b)) of the stainless steel base material 27 is dissolved by the solvent 48, the stainless steel films 28 on the exposed surfaces 21b of the conductive materials 21 can be dissolved.
Thus, the exposed surfaces 21b of the conductive materials 21 can be cueed from the melting surface 27b of the stainless steel base material 27.

In (b), after the completion of the melting of the stainless steel base material 27, a passive film 70 is formed on the melting surface 27 b of the stainless steel base material 27.
In this state, the exposed surfaces 21b of the conductive materials 21 are cleaved from the surface of the passive film 70 by a height t5.

Modification of reference form
In the manufacturing method of the reference form , in the forming step of ST55, the example in which the rolled material with the exposed surface of the conductive material protruding on the surface is press-formed to the separator has been described. However, the present invention is not limited to this, and the flattening step of ST53 It is also possible to carry out the molding process of ST55 between the melting process of ST54.
Further, it is possible to perform the forming process of ST55 between the surface layer removing process of ST52 and the flattening process of ST53.
By diversifying the manufacturing method, it becomes possible to select a suitable manufacturing method from various manufacturing methods according to the situation.

According to the manufacturing method of a reference form and its modification, the effect similar to the manufacturing method of 1st Embodiment can be acquired.

Fifth Embodiment FIG. 18 is a diagram for explaining a fifth embodiment of a method for producing a conductive material-containing stainless steel separator according to the present invention.
In the first to fourth embodiments and the reference embodiment , the example in which the grindstones 46, 53, 63 for surface grinding are used as the grindstone has been described. However, instead of the grindstones 46, 53, 63 for surface grinding, cylindrical grinding is used. It is also possible to use the whetstone 81.

The grindstone 81 is rotated about the rotary shaft 82 as indicated by an arrow h, and the surface plate 83 is moved as indicated by an arrow i, whereby the separator 13 is moved integrally with the surface plate 83 as indicated by an arrow i.
In this state, the convex portions 29 of the separator 13 are ground by pressing the grinding surface (outer peripheral surface) of the grinding wheel 81 for cylindrical grinding.

  Here, the grindstone 81 for cylindrical grinding has a smaller contact area with the convex portions 29 than the grindstones 46, 53, 63 for surface grinding of the first to fourth embodiments. Therefore, the rotational speed of the grinding wheel 81 for cylindrical grinding can be increased as compared with the grinding wheels 46, 53, 63 for surface grinding of the first to fourth embodiments.

In the above-described embodiment, boride (boride) is illustrated as an example of the conductive material 21, and chromium boride (Cr ₂ B) is illustrated as an example of the boride. It is not limited.
For example, a carbide may be used as the conductive material 21 instead of the boride. In short, any material that can increase the conductivity of the separator 12 may be used.

  In the above embodiment, the thickness t2 of the surface layer 34 is 3 μm, the grinding amount t3 of the grinding surface 47 is 10 μm, the film thickness t4 of the stainless steel film 28 is 0.1 μm or less, and the dissolution amount by the solvent 48 (the cutting allowance) However, the value of t2 to t4 and the value of the amount of melting (cutting allowance) are not limited to this.

Further, in the above-described embodiment, the example in which a solution (so-called nitric hydrofluoric acid) in which 20% nitric acid is added to 8% hydrofluoric acid is used as the solvent for dissolving the stainless steel film 28 is described. However, the present invention is not limited to this.
In the above embodiment, the example in which the stainless steel film 28 is removed by precision machining by grinding the grindstone 63 in the stainless steel film removal step has been described. However, the present invention is not limited to this, and dissolution using a solvent (that is, dissolution) It is also possible to remove the stainless steel film 28 by other precision processing such as lapping using loose abrasive grains.
Here, an example of lapping will be described with reference to FIG.

FIG. 19 is a diagram for explaining lapping in the method for producing a conductive material-containing stainless steel separator according to the present invention.
The separator 13 is bonded to the plate 90 with the adhesive tape 91. The convex portions 26 of the separator 13 are pressed against a surface plate (casting) 92.
At this time, the stainless steel film 28 (see FIGS. 7C, 12C, and 16C) of the convex portions 26 is pressed against the surface plate 92 with a predetermined pressing force. In order to obtain a predetermined pressing force, a weight (6 kg) was used.

In this state, while supplying the slurry 93, the surface plate 92 is rotated as indicated by the arrow about the rotation shaft 92a, and the stainless steel film 28 is ground by rotating the plate 90 as indicated by the arrow about the rotation shaft 90a. . This grinding time is 5 minutes.
Thereby, the stainless steel films 28 can be removed from the exposed surfaces 21b of the conductive materials 21 (see FIGS. 7C, 12C, and 16C).
Here, as the slurry 93, an abrasive having a particle diameter of 4 to 8 [mu] m (as an example, diamond) was used.
Further, the rotation speed of the surface plate 92 was set to approximately 30 rpm, and the rotation speed of the plate 90 was set to approximately 30 rpm.

  INDUSTRIAL APPLICABILITY The present invention is suitable for a method of manufacturing a conductive material-containing stainless steel separator that manufactures a separator using a stainless steel material containing a granular conductive material in a stainless steel base material.

It is sectional drawing which shows the fuel cell of a fuel cell. It is a flowchart explaining 1st Embodiment of the manufacturing method of the electroconductive material containing stainless steel separator which concerns on this invention. It is a figure explaining the process of rolling a raw material in the manufacturing method of 1st Embodiment. It is a figure explaining the process of press-molding a separator in the manufacturing method of a 1st embodiment. It is a figure explaining the process of setting a separator to a grinding machine in the manufacturing method of a 1st embodiment. It is a figure explaining the process of removing a surface layer in the manufacturing method of 1st Embodiment. It is a figure explaining the process of planarizing the exposed surface of a conductor in the manufacturing method of a 1st embodiment. It is a figure explaining the process of removing a stainless steel film in the manufacturing method of a 1st embodiment. It is a figure explaining the process of cueing a conductor in the manufacturing method of a 1st embodiment. It is a figure explaining the example which used the separator manufactured with the manufacturing method of 1st Embodiment for the fuel cell. It is a flowchart explaining 2nd Embodiment of the manufacturing method of the electroconductive material containing stainless steel separator which concerns on this invention. It is a figure explaining the surface layer removal / planarization process in the manufacturing method of 2nd Embodiment. It is a flowchart explaining 3rd Embodiment of the manufacturing method of the electroconductive material containing stainless steel separator which concerns on this invention. It is a flowchart explaining 4th Embodiment of the manufacturing method of the electroconductive material containing stainless steel separator which concerns on this invention. It is a flowchart explaining the reference form of the manufacturing method of the electroconductive material containing stainless steel separator which concerns on this invention. It is a figure explaining the surface layer removal process and planarization process in the manufacturing method of a reference form . It is a figure explaining the melt | dissolution process in the manufacturing method of a reference form . It is a figure explaining 5th Embodiment of the manufacturing method of the electroconductive material containing stainless steel separator which concerns on this invention. It is a figure explaining the lapping process of the manufacturing method of the electrically conductive substance containing stainless steel separator which concerns on this invention. It is a figure explaining the manufacturing process of the conventional metal separator. It is a figure which shows the state which made the conventional metal separator contact the membrane electrode assembly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 12 ... Membrane electrode assembly (MEA), 13 ... Separator, 21 ... Conductive material, 21b ... Exposed surface, 22 ... Stainless steel material, 23 ... Rolled material, 26 ... Projection part of separator, 27 ... Stainless steel mother 27a ... surface of stainless steel base material, 27b ... melting surface of stainless steel base material, 28 ... stainless steel film, 34 ... surface layer, 45, 54, 64 ... rotating shaft, 46, 53, 63 ... grindstone, 46a, 53a, 63a ... cutting blade surface, 47 ... grinding surface, 48 ... solvent.

Claims (4)

Stainless base material made of stainless steel material which contains a conductive material consisting of borides or carbides of granular chromium, met method for manufacturing a fuel cell separator having a convex portion in contact with one side of the membrane electrode assembly And
A preparation step of preparing a stainless steel material which contains a conductive material of the granular stainless base material,
Rolling process to obtain a rolled material by rolling the stainless steel material to a predetermined thickness;
The rolled material by press-forming, a forming step that form a convex portion in contact with one surface of the membrane electrode assembly in the rolling material,
A surface layer removing step of removing only the surface layer of the convex portion of the rolled material forming the convex portion;
Wherein to surface a against the grinding wheel surface removal grinding of the rolled material, to expose the conductive material on the surface of a stainless base material, flattening to flatten the exposed surface of the surface and the conductive material of the stainless steel base metal Process,
Subjecting the solvent grinding the surface of the rolled material, while keeping the non-dissolving the conductive material in the solvent to dissolve the stainless base material, a melting step the stainless base material that Hekomase than the exposed surface of the conductive material A process for producing a conductive material-containing stainless steel separator.   The method for producing a conductive material-containing stainless steel separator according to claim 1, wherein the surface layer removing step and the flattening step are performed simultaneously.   The conductive film according to claim 1 or 2, wherein a stainless steel film removing step for removing a stainless steel film from an exposed surface of the flattened conductive material is added between the flattening step and the melting step. Of manufacturing a material-containing stainless steel separator.   The conductor according to any one of claims 1 to 3, wherein in the surface layer removing step and the flattening step, these steps are performed with a grindstone in which a rotation axis is arranged perpendicular to the stainless steel material. A method for producing a stainless steel separator.

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