阅读说明：本技术 燃料电池的隔板用不锈钢板及其制造方法 (The partition stainless steel plate and its manufacturing method of fuel cell ) 是由 矢野孝宜 石川伸 于 2018-04-02 设计创作，主要内容包括：设定为规定的成分组成,在不锈钢板的表面形成凸部间的平均间隔为20nm以上且200nm以下的凹凸结构,并且,使在不锈钢板的表面以金属以外的形态存在的Cr的原子浓度相对于以金属以外的形态存在的Fe的原子浓度的比、即[Cr]/[Fe]为2.0以上。(At being grouped as defined in being set as, it is 20nm or more and 200nm concaveconvex structure below in the equispaced that the surface of stainless steel plate is formed between protrusion, also, the atomic concentration of Cr existing for making on the surface of stainless steel plate in the form of other than metal is 2.0 or more relative to ratio, i.e. [Cr]/[Fe] of the atomic concentration of Fe existing in the form of other than metal.)

1. a kind of partition stainless steel plate of fuel cell, wherein

The surface of the stainless steel plate has the concaveconvex structure with recess portion and protrusion, the equispaced between the protrusion be 20nm with Upper and 200nm hereinafter,

The surface of the stainless steel plate in the form of other than metal existing for Cr atomic concentration relative to metal other than The ratio of the atomic concentration of Fe existing for form, i.e. [Cr]/[Fe] are 2.0 or more.

2. a kind of manufacturing method of the partition stainless steel plate of fuel cell, wherein

Prepare the stainless steel plate as former material,

Then, etching process is implemented to the stainless steel plate of the preparation,

Then, the stainless steel plate for implementing etching process to described implement on its surface in the form of other than metal existing for Cr Concentration,

The concaveconvex structure with recess portion and protrusion is formed on the surface of the stainless steel plate as a result, is made between average between the protrusion 20nm or more is divided into and 200nm hereinafter, and Cr existing for making on the surface of the stainless steel plate in the form of other than metal Atomic concentration is 2.0 or more relative to ratio, i.e. [Cr]/[Fe] of the atomic concentration of Fe existing in the form of other than metal.

3. the manufacturing method of the partition stainless steel plate of fuel cell as claimed in claim 2, wherein the etching process is Impregnation in the solution containing hydrofluoric acid.

4. the manufacturing method of the partition stainless steel plate of fuel cell as claimed in claim 2 or claim 3, wherein implement the erosion Before quarter processing, implement the group for utilizing anode electrolysis, catholyte or anode electrolysis and catholyte to the stainless steel plate Close the electrolysis processing carried out.

5. the manufacturing method of the partition stainless steel plate of the fuel cell as described in any one of claim 2~4, wherein institute The concentration for stating Cr is impregnation in the solution with oxidisability or the current potential that the stainless steel plate is passivated Electrolysis processing in range.

Technical field

The present invention relates to the partition stainless steel plates and its manufacturing method of fuel cell.

Background technique

In recent years, from the viewpoint of environment of preserving our planet, excellent in power generation efficiency and the fuel electricity for not discharging carbon dioxide The exploitation in pond is carrying out.The fuel cell generates electricity by electrochemical reaction by hydrogen and oxygen, therefore, basic structure tool There is the structure similar to sandwich, by dielectric film (amberplex), two electrodes (fuel electrodes and air pole), O₂(air) And H₂Diffusion layer and two partitions (Bipolar plate, bipolar plates) constitute.

In addition, being categorized into phosphoric acid type fuel cell, fused carbonate type fuel according to the type of used dielectric film Battery, solid oxide fuel cell, alkaline fuel cell and polymer electrolyte fuel cell (PEFC；proton- Exchange membrane fuel cell (Proton Exchange Membrane Fuel Cells) or polymer electrolyte fuel Cell (polymer electrolyte fuel cells)), respectively developed.

In these fuel cells, especially polymer electrolyte fuel cell is expected to the carrying electricity consumption as electric car Source, home-use or work fixation generator, portable small generator.

Polymer electrolyte fuel cell, by hydrogen and oxygen extraction electricity, utilizes gas diffusion layers (example by polymeric membrane Such as carbon paper) and partition clamp film-electrode bond, as single constituent element (so-called monocell).Then, it is firing Electromotive force is generated between material pole side partition and air pole side partition.

It should be noted that above-mentioned film-electrode bond is referred to as MEA (membrane-electrode assembly, Membrane- Electrode Assembly), it is that polymeric membrane is loaded into the carbon black etc. for having platinum group catalyst on the surface of the film and the back side Made of electrode material integration, with a thickness of tens μm~several hundred μm.In addition, gas diffusion layers and film-electrode bond one The case where change, is also more.

In addition, by polymer electrolyte fuel cell for it is practical in the case where, usually by monocell as described above Be connected in series tens~it is several hundred and constitute fuel cell pack come using.

Here, not requiring nothing more than the effect for separating the partition between monocell as (a) for partition, also requiring conduct (b) hydrogen gas flow path, (d) of the electric conductor of the electronics generated, the air flow circuit of (c) oxygen (air) circulation, hydrogen circulation are transported The function for the drain passageway (double as air flow circuit, hydrogen gas flow path) that the water of generation, gas are discharged, therefore, it is necessary to excellent resistance to Long property, electric conductivity.

Here, durability is determined by corrosion resistance.The reason is that if partition occurs to corrode and digestion of metallic ion, Then the proton-conducting of polymeric membrane (dielectric film) reduces, and power generation characteristics reduce.

In addition, about electric conductivity (conductivity), it is expected that the contact resistance of partition and gas diffusion layers is as low as possible. The reason is that if the contact resistance of partition and gas diffusion layers increases, the power generation effect of polymer electrolyte fuel cell Rate reduces.That is, it can be said that the contact resistance of partition and gas diffusion layers is smaller, then power generation characteristics are more excellent.

So far, graphite is used just to be practical as the polymer electrolyte fuel cell of partition.It is this by graphite The advantage that partition of composition has contact resistance lower and does not corrode.But the partition of graphite is easy because touching Hit and damaged, thus have and be not only difficult to minimize but also be used to form air flow circuit, the processing cost of hydrogen gas flow path high lacks Point.These disadvantages possessed by the partition being made of graphite become the reason for interfering polymer electrolyte fuel cell universal.

Therefore, applied metal former material is try to instead of former material of the graphite as partition.In particular, from durability is improved Viewpoint is set out, and the functionization towards the partition using stainless steel, titanium, titanium alloy etc. as former material has carried out various researchs.

For example, Patent Document 1 discloses use the metal of the passivating film easy to form such as stainless steel or titanium alloy as The technology of partition.

But in the technique disclosed in Patent Document 1, with the formation of passivating film, lead to the raising of contact resistance, lead Cause the reduction of generating efficiency.In this way, to there is the contact resistance compared with graphite former material big etc. for metal former material disclosed in Patent Document 1 Problem.

Therefore, for the reduction of such contact resistance, for example, Patent Document 2 discloses: a kind of " corrosion resistant Corrosion and high conductive ferrite-group stainless steel, which is characterized in that contain C:0.001~0.05%, Si in terms of quality %: 0.001~0.5%, Mn:0.001~1.0%, Al:0.001~0.5%, N:0.001~0.05%, Cr:17~23%, Mo: 0.1%, hereinafter, surplus is made of Fe and inevitable impurity, has on its surface and is obtained and being impregnated in dipping treatment solution The overlay film arrived, the dipping treatment solution are expressed as based on hydrofluoric acid or hydrofluoric acid nitric acid and by hydrofluoric acid concentration [HF], concentration of nitric acid is expressed as [HNO₃] in the case where have formula: [HF] >=[HNO₃] ... the relationship of [1] ".

In addition, Patent Document 3 discloses: " a kind of manufacturing method of fuel cell separator plate stainless steel, feature exist In after implementing electrolysis processing to the stainless steel of the Cr containing 16 mass % or more, implementation is at the dipping in the solution containing fluorine Reason ".

In addition, Patent Document 4 discloses: " a kind of fuel cell separator plate stainless steel, contains C in terms of quality %: 0.03% or less, Si:1.0% or less, Mn:1.0% or less, S:0.01% or less, P:0.05% or less, Al:0.20% or less, N:0.03% or less, Cr:16~40%, and contain one in Ni:20% or less, Cu:0.6% or less, Mo:2.5% or less Kind or more, surplus is made of Fe and inevitable impurity, which is characterized in that using electron spectroscopy for chemical analysis to the table of the stainless steel In the case that face is measured, detect F, also, meet other than metal form (Cr+Fe)/metal form (Cr+Fe) >= 3.0”。

In addition, Patent Document 5 discloses: " a kind of fuel cell separator plate stainless steel that surface contacted resistance is low, Cr containing 16~40 mass %, which is characterized in that on the surface of the stainless steel, the region with fine concaveconvex structure is with face There are 50% or more for product rate meter ".

In addition, Patent Document 6 discloses: " a kind of separator for solid polymer fuel cell, which is characterized in that By being formed with micro- hole that size is 0.01~1 μm containing the mass of Cr:16~40 mass of %, Mo:1~5 %, in surface whole region Stainless steel plate constitute, and substrate surface be formed in the form of oxide and/or hydroxide be included in passivating film in Cr, Fe atomicity ratio Cr/Fe be 4 or more passivating film ".

Summary of the invention

Problem to be solved by the invention

But when stainless steel plate disclosed in patent document 2~6 is actually used as the partition of fuel cell, exists and connect Electric shock resistance does not reduce, thus the case where cannot get desired power generation characteristics in the stage of former material steel plate as expected.

The present invention is to develop to solve the above-mentioned problems, and it is an object of the present invention to provide a kind of partition as fuel cell makes The partition stainless steel plate of the fuel cell of used time available low contact resistance.

In addition, the purpose of the present invention is to provide the manufacturing methods of the partition stainless steel plate of above-mentioned fuel cell.

The method for solving problem

The present inventor has made intensive studies to solve the above-mentioned problems.

Firstly, contact resistance is not in former material steel when the present inventor is to the partition that stainless steel plate is actually used as to fuel cell The stage of plate is studied the reason of reduction as expected.

As a result, discovery, in the process for manufacturing fuel cell pack and cells in series is connected tens~several hundred In (hereinafter also referred to fuel cell pack manufacturing process), implement heat treatment, when the heat treatment, the stainless steel as partition sometimes The passivating film on surface grows thicker, grow in some cases it is thick to should substantially be referred to as oxidation overlay film degree, by This, compared with the stage of former material steel plate, the electric conductivity of surface of steel plate is reduced, and contact resistance increases.

Therefore, inventors believe that may be, if it is possible to inhibit the growth of the passivating film, even if then in fuel cell pack Implement heat treatment etc. in manufacturing process, can also reduce the raising of contact resistance.

Based on the design, research has further been repeated in the present inventor, has as a result obtained following opinion:

Defined concaveconvex structure is formed on the surface of stainless steel plate,

On this basis, improve the surface of stainless steel plate in the form of other than metal existing for Cr atomic concentration phase For the ratio of the atomic concentration of Fe existing in the form of other than metal,

Thereby, it is possible to reduce the contact resistance in the stage of former material steel plate, also, even if in fuel cell pack manufacturing process Middle implementation heat treatment etc. is also able to maintain that low contact resistance.

For its reason, inventors believe that as follows.

That is, present inventors believe that

When concaveconvex structure as defined in being formed on the surface of stainless steel plate, the contact area of stainless steel and gas diffusion layers increases Greatly, contact resistance reduces, still,

When the stainless steel plate in such a state is exposed under the heat treatment environment of fuel cell pack manufacturing process, It thickeing in the passivating film growth of the Surface Creation of stainless steel plate, contact resistance increases,

But make on the basis of the concaveconvex structure as defined in the surface of stainless steel plate forms on the surface of stainless steel plate When the atomic concentration of Cr existing in the form of other than metal increases, the Cr concentration in passivating film increases, even if the stainless steel plate The growth for being exposed to passivating film under heat treatment environment as described above is also inhibited,

In addition, even if the atomic concentration of Cr existing for making on the surface of stainless steel plate in the form of other than metal increases, Also big influence is not brought to the contact resistance of the stainless steel plate in former material stage,

According to above content, for stainless steel plate of the invention, it can reduce and connect in the stage of former material steel plate Electric shock resistance, also, even if implement the feelings of heat treatment etc., the partition for being actually used as fuel cell in fuel cell pack manufacturing process Under condition, low contact resistance can be also maintained.

In addition, research has further been repeated in the present inventor, following opinion has as a result been obtained:

The surface state of stainless steel plate as described above in order to obtain,

Particularly advantageously, stainless steel plate is immersed in the solution containing hydrofluoric acid and is etched, as a result, not The surface of rust steel plate forms concaveconvex structure, then, implements leaching in the solution with oxidisability to the stainless steel after etching process Stain processing or the implementation electrolysis processing in the potential range that stainless steel plate is passivated,

Thereby, it is possible to maintain stainless steel plate surface concaveconvex structure in the state of improve the surface of stainless steel plate with Ratio of the atomic concentration of Cr existing for form other than metal relative to the atomic concentration of Fe existing in the form of other than metal.

In addition following opinion is also obtained: before being etched, being pre-processed under the defined conditions, by This, can stably obtain the reducing effect of contact resistance, and stability when carrying out volume production in physical device (is hereinafter also referred to measured Produce stability) it greatly improves.

The present invention is that research is further repeated based on above-mentioned opinion and completes.

That is, purport of the invention is constituted as described below.

1. a kind of partition stainless steel plate of fuel cell, wherein

The surface of above-mentioned stainless steel plate has the concaveconvex structure with recess portion and protrusion, and the equispaced between the protrusion is 20nm or more and 200nm hereinafter,

The surface of above-mentioned stainless steel plate in the form of other than metal existing for Cr atomic concentration relative to metal with The ratio of the atomic concentration of Fe existing for outer form, i.e. [Cr]/[Fe] are 2.0 or more.

2. a kind of manufacturing method of the partition stainless steel plate of fuel cell, wherein

Prepare the stainless steel plate as former material,

Then, etching process is implemented to the stainless steel plate of above-mentioned preparation,

Then, existing for the stainless steel plate for implementing etching process to above-mentioned is implemented on its surface in the form of other than metal The concentration of Cr,

The concaveconvex structure with recess portion and protrusion is formed on the surface of above-mentioned stainless steel plate as a result, is made flat between the protrusion 20nm or more is divided into and 200nm between hereinafter, and existing for making on the surface of above-mentioned stainless steel plate in the form of other than metal The atomic concentration of Cr relative to ratio, i.e. [Cr]/[Fe] of the atomic concentration of Fe existing in the form of other than metal be 2.0 with On.

3. the manufacturing method of the partition stainless steel plate of the fuel cell as described in above-mentioned 2, wherein above-mentioned etching process is Impregnation in the solution containing hydrofluoric acid.

4. the manufacturing method of the partition stainless steel plate of the fuel cell as described in above-mentioned 2 or 3, wherein implement above-mentioned erosion Before quarter processing, implement the group for utilizing anode electrolysis, catholyte or anode electrolysis and catholyte to above-mentioned stainless steel plate Close the electrolysis processing carried out.

5. the manufacturing method of the partition stainless steel plate of the fuel cell as described in above-mentioned any one of 2~4, wherein on The concentration for stating Cr is impregnation in the solution with oxidisability or the current potential that above-mentioned stainless steel plate is passivated Electrolysis processing in range.

Invention effect

In accordance with the invention it is possible to obtain the partition stainless steel plate of the fuel cell with low contact resistance with low cost. In addition, the partition stainless steel plate of fuel cell of the invention is if exposed to the heat treatment ring in fuel cell pack manufacturing process Also low contact resistance can be maintained under border, it is therefore, practical extremely beneficial.

In addition, the partition stainless steel plate of fuel cell of the invention is in the growth for being exposed to the passivating film such as surface of steel plate It can be also advantageously used in the case of being promoted other than above-mentioned under such environment.

Specific embodiment

(1) the partition stainless steel plate of fuel cell

For the partition stainless steel plate of the fuel cell of an embodiment of the invention, being formed on surface has The defined concaveconvex structure of recess portion and protrusion.Firstly, being illustrated to the concaveconvex structure.

Equispaced between protrusion: 20nm or more and 200nm or less

The equispaced 20nm or more between protrusion and 200nm by making surface of steel plate is hereinafter, low contact can be obtained Resistance.

Here, concave-convex interval becomes too small when the equispaced between protrusion is less than 20nm, concave-convex and gas diffusion layers etc. Fuel cell member of formation contacts with being unable to fully, and is unable to get desired contact resistance.

On the other hand, when the equispaced between protrusion is more than 200nm, it cannot make concave-convex fine and thickly be dispersed in steel plate table Face is unable to get the increase effect of sufficient contact area, is still unable to get desired contact resistance.In addition, by steel plate When being processed into partition shape, the bumps of surface of steel plate become starting point, are easy to produce crackle, rough surface etc..

Therefore, the equispaced between protrusion is set as 20nm or more and 200nm or less.Preferably 30nm or more, more preferably For 40nm or more.Additionally, it is preferred that being 150nm hereinafter, more preferably 100nm or less.

It should be noted that the equispaced between protrusion described herein is the value found out as follows.

That is, utilizing the scanning electron microscope for having field emission type cold cathode electron gun in the matrix surface to stainless steel plate (S-4100 that FE-SEM, Hitachi manufacture) is when acceleration voltage to be set as 3kV, observe 10 visuals field with 30000 times of multiplying power In the photo (SEM photograph) of obtained secondary electron image, for each visual field, along rolling direction and with rolling direction Cheng Zhi The line segment that three length are 2 μm is drawn respectively with 1 μm of interval in the direction at angle, measures the number of the protrusion on each line segment.Then, Using the line segment length divided by measurement protrusion number, the equispaced between the protrusion of each line segment is thus found out, by it Be averaged, find out the equispaced between protrusion as a result,.

In addition, recess portion (part other than protrusion) is used as dark space in the photo (SEM photograph) of above-mentioned secondary electron image Both domain is observed, and protrusion is observed as bright area, therefore, can thus identify.

In addition, for the partition stainless steel plate of the fuel cell of an embodiment of the invention, in stainless steel The surface of plate is formed on the basis of above-mentioned concaveconvex structure, improve in the form of other than metal existing for Cr atomic concentration relative to The ratio of the atomic concentration of Fe existing in the form of other than metal is critically important.

The surface of stainless steel plate in the form of other than metal existing for Cr atomic concentration relative to metal other than The ratio of the atomic concentration of Fe existing for form: 2.0 or more

By the atomic concentration of Cr existing for making on the surface of stainless steel plate in the form of other than metal relative to metal The ratio (hereinafter also referred to [Cr]/[Fe]) of the atomic concentration of Fe existing for form in addition is 2.0 or more, even if being exposed to combustion When expecting under the heat treatment environment in battery pile manufacturing process, it is also able to suppress the growth in the passivating film of surface of steel plate.Its result It is to be able to maintain that low contact resistance.Preferably 2.5 or more.

It should be noted that from the viewpoint of inhibit the growth of the passivating film of surface of steel plate, [Cr]/[Fe] it is more big more Favorably, therefore, the upper limit is not particularly limited, typically about 20.

In addition, the form of Shape Representation oxide and hydroxide other than metal.Specifically, in the case where Cr, it can To enumerate CrO₂、Cr₂O₃、CrOOH、Cr(OH)₃And CrO₃Deng.In addition, FeO, Fe can be enumerated in the case where Fe₃O₄、Fe₂O₃With FeOOH etc..

Here, [Cr]/[Fe] can be found out as follows.

That is, being measured using X-ray photoelectron spectroscopy (hereinafter also referred to XPS) to the surface of stainless steel plate, by institute The peak of obtained Cr and Fe be separated into respectively the peak of the Cr and Fe existing for the metal form in the form of other than metal existing for The peak of Cr and Fe, utilization thus it is calculated in the form of other than metal existing for Cr atomic concentration divided by other than with metal The atomic concentration of Fe existing for form, so as to find out [Cr]/[Fe].

Specifically, it is as follows the value found out: being cut into the sample of 10mm square from steel plate, using the sample, use Al-K α monochromatic X-ray source utilizes x-ray photoelectron spectroscopy device (Shimadzu/KRATOS corporation under conditions of extracting angle and being 45 degree The AXIS-HS made) it is measured, other than the peak of Cr and Fe is separated into the peak of Cr existing for metal form and Fe and with metal Form existing for Cr and Fe peak, utilization thus it is calculated in the form of other than metal existing for Cr atomic concentration divided by The atomic concentration of Fe existing in the form of other than metal and find out.It should be noted that peak separation is by utilizing Shirley method It removes the background of spectrogram and uses Gauss-Lorentz (Gauss-Lorentz) compound function (ratio of Lorentzian: 30%) To implement.

In addition, being not particularly limited at being grouped as stainless steel plate, is preferably set to contain C:0.100% in terms of quality % Below, Si:2.00% or less, Mn:2.00% or less, P:0.050% or less, S:0.010% or less, Cr:11.0~40.0%, Al:0.500% or less and N:0.100% or less, surplus be made of Fe and inevitable impurity at being grouped as.

Hereinafter, being illustrated to its reason.It should be noted that unless otherwise specified, it is related with ingredient " % " Expression refers to quality %.

C:0.100% or less

C reacts with the Cr in stainless steel, is precipitated in the form of Cr carbide in crystal boundary, therefore, leads to corrosion resistance Reduction.Therefore, from the viewpoint of corrosion resistance, the C the few the more preferred, and C content is preferably set to 0.100% or less.It is more excellent It is selected as 0.030% or less.Further preferably 0.020% or less.It should be noted that lower limit is not particularly limited, it is excellent Choosing is set as about 0.001%.

Si:2.00% or less

Si is the effective element for deoxidation, is added in the smelt stage of stainless steel.The effect is by preferably comprising 0.01% or more and obtain.But when containing excessive Si, hardening occurs for stainless steel, and ductility is easily reduced.Therefore, Si Content is preferably set to 2.00% or less.More preferably 0.60% or less.

Mn:2.00% or less

Mn is the effective element for deoxidation, is added in the smelt stage of stainless steel.The effect is by preferably comprising 0.01% or more and obtain.But Mn content, when being more than 2.00%, corrosion resistance is easily reduced.Therefore, Mn content is preferably set It is 2.0% or less.More preferably 1.00% or less.

P:0.050% or less

P leads to the reduction of ductility, and therefore, the less content the better.When P content is 0.050% or less, it will not occur The significant decrease of ductility.Therefore, P content is preferably set to 0.050% or less.More preferably 0.040% or less.For lower limit It is not particularly limited, but excessive de- P leads to the increase of cost, it is therefore preferable that being set as about 0.010%.

S:0.010% or less

S is the element for forming MnS in conjunction with Mn and reducing corrosion resistance.When S content is 0.010% or less, Bu Huifa The significant decrease of raw corrosion resistance.Therefore, S content is preferably set to 0.010% or less.Lower limit is not particularly limited, but It is that excessive de- S leads to the increase of cost, it is therefore preferable that being set as about 0.001%.

Cr:11.0~40.0%

In order to ensure corrosion resistance, Cr content is preferably set to 11.0% or more.That is, when Cr content is less than 11.0%, from It sets out in terms of corrosion resistance, it is possible to be difficult to be resistant to prolonged use as the partition of fuel cell.Preferably 16.0% More than.On the other hand, when Cr content is more than 40.0%, toughness is caused to reduce because of the precipitation of σ phase sometimes.Therefore, Cr content is excellent Choosing is set as 40.0% or less.More preferably 32.0% or less.

Al:0.500% or less

Al is the element for deoxidation.The effect is obtained and preferably comprising 0.001% or more.But Al content is super When 0.500%, the reduction of ductility is occasionally resulted in.Therefore, Al content is preferably set to 0.500% or less.More preferably 0.150% or less.

N:0.100% or less

When N content is more than 0.100%, formability is reduced.Therefore, N content is preferably set to 0.100% or less.More preferably It is 0.030% or less.Further preferably 0.020% or less.Lower limit is not particularly limited, but excessive de- N causes The increase of cost, it is therefore preferable that being set as about 0.002%.

More than, basis is illustrated, still, other than above-mentioned basis, can also containing below at Point.

Ni:30.00% or less

Ni is the effective element for improving the corrosion resistance of stainless steel.In addition, in general, austenite stainless steel, Contain a certain amount of Ni in Austenite and ferriteaustenite double phases of stainless steel.But Ni content is when being more than 30.00%, hot-workability drop It is low.Therefore, in the case where containing Ni, Ni content is set as 30.00% or less.It should be noted that austenite stainless steel, iron The preferred lower limit of Ni content in ferritic-austenitic duplex stainless steel is 2.00%.

In addition, Ni content is preferably set to 2.00% or less in the case where containing Ni in ferrite-group stainless steel.It is more excellent It is selected as 1.00% or less.It should be noted that the preferred lower limit in ferrite-group stainless steel is 0.01%.

Cu:2.50% or less

Cu is the effective element for improving the corrosion resistance of stainless steel.The effect by preferably comprise 0.01% with It is upper to obtain.But Cu content, when being more than 2.50%, hot-workability reduces, and leads to the reduction of productivity.Therefore, containing Cu's In the case of, Cu content is set as 2.50% or less.

Mo:4.00% or less

Mo is the effective element for inhibiting the local corrosions such as the crevice corrosion of stainless steel.The effect is by preferably containing Have 0.01% or more and obtains.But Mo content leads to the embrittlement of stainless steel when being more than 4.00%.Therefore, containing Mo the case where Under, Mo content is set as 4.00% or less.

Element selected from one or more of Ti, Nb and Zr: 1.00% or less is added up to

Ti, Nb and Zr help to improve resistance to grain boundary corrosion, can be independent or compound contain these elements.The effect passes through It is preferred that being obtained respectively containing 0.01% or more.But total content of these elements, when being more than 1.00%, ductility is easy drop It is low.Therefore, in the case where containing Ti, Nb and Zr, their total content is set as 1.00% or less.It is not special for lower limit It limits, is preferably set as 0.01% with total content meter of Ti, Nb and Zr.

It should be noted that ingredient other than the above is Fe and inevitable impurity.

In addition, in view of mounting space, weight in the case of fuel cell pack, the plate thickness of stainless steel plate is preferably set to 0.03 The range of~0.30mm.When plate thickness is less than 0.03mm, the production efficiency of metal plate former material is reduced.On the other hand, more than 0.30mm When, mounting space, weight in the case of fuel cell pack increase.The more preferably range of 0.03~0.10mm.

(3) manufacturing method

Then, the manufacturing method of the partition stainless steel plate of the fuel cell of an embodiment of the invention is said It is bright.

Preparatory process

Preparatory process is the process for preparing the stainless steel plate as former material.About the stainless steel plate as former material, without spy It does not limit, for example, preparing the stainless steel plate with mentioned component composition as described below.

That is, hot rolling is carried out to the steel billet formed with mentioned component and hot rolled plate is made, it is real as needed to the hot rolled plate Hot rolled plate annealing is applied, then, hot rolled plate implementation cold rolling is made the cold-reduced sheet of desired plate thickness, then as needed to this Cold-reduced sheet implements cold-reduced sheet annealing, the stainless steel plate that thereby, it is possible to prepare that there is mentioned component to form.

It should be noted that the condition of hot rolling, cold rolling, hot rolled plate annealing, cold-reduced sheet annealing etc. is not particularly limited, according to Conventional method.Furthermore it is possible to implement pickling, skin-pass after cold-reduced sheet annealing.Alternatively, it is also possible to use cold-reduced sheet It is annealed into the stainless steel plate of bright annealing.

The pretreatment process of etching process

As the pretreatment of aftermentioned etching process (processing of concaveconvex structure as defined in being formed on the surface of steel plate), to not The steel plate that becomes rusty implements electrolysis processing, removes the oxidation overlay film formed on the surface of the stainless steel plate prepared.It as a result, can be steady Surely the reducing effect of contact resistance brought by aftermentioned etching process is obtained, volume production stability greatly improves.

Here, the oxidation overlay film in the formation of the surface of stainless steel plate can enumerate the passivating film formed in an atmosphere, make For the fabrication stage of the stainless steel plate of former material bright annealing when the BA overlay film etc. that is formed.

It is therefore preferable that carrying out pretreatment of the electrolysis processing as etching process.It should be noted that electrolysis processing can benefit Implemented with the combination of anode electrolysis, catholyte or anode electrolysis and catholyte, from the viewpoint for improving volume production stability It sets out, particularly preferred catholyte.

That is, if the combination using anode electrolysis, catholyte or anode electrolysis and catholyte carries out electrolysis processing As the pretreatment of etching process, then can remove on the surface of the stainless steel plate prepared in either event The oxidation overlay film of formation, to contribute effectively to the stabilisation of contact resistance reducing effect brought by etching process.Especially It is in the case where only catholyte being utilized to implement pretreated situation, when volume production is also not easily susceptible to the bad shadow of the deterioration of etching process liquid It rings, can more effectively and steadily remove the oxidation overlay film of stainless steel surface, therefore, connecing after can more stably being etched Electric shock resistance reducing effect.Therefore, the electrolysis processing carried out as the pretreatment of etching process is particularly preferably catholyte.

It should be noted that treatment fluid is not particularly limited, such as preferably aqueous sulfuric acid.

In addition, the conductivity that the concentration for the treatment of fluid is adjusted to treatment fluid is sufficiently high, for example, the case where aqueous sulfuric acid It is preferably from about 10g/L~about 100g/L down.

In addition, treatment temperature is not particularly limited, preferably 30~85 DEG C.

It is pre-processed before etching process as described above, the reducing effect of contact resistance can be stably obtained as a result, Volume production stability greatly improves.

It should be noted that in the case where anode electrolysis, preferably making energization electricity+0.1 as electrolysis treatment conditions ~+6000C/dm²(current density :+0.1~+10A/dm², electrolysis time: 1~600 second) in the range of be adjusted, in cathode In the case where electrolysis, preferably in -0.1~-6000C/dm²(current density: -0.1~-10A/dm², electrolysis time: 1~600 second) In the range of be adjusted.

In addition, the electrolysis treatment conditions in the case where about combined anode electrolysis and catholyte, preferably: anode electrolysis exists Make+0.1~+6000C/dm of energization electricity²(current density :+0.1~+10A/dm², electrolysis time: 1~600 second) range It is inside adjusted, catholyte is in -0.1~-6000C/dm²(current density: -0.1~-10A/dm², electrolysis time: 1~600 Second) in the range of be adjusted, and they are combined.

In addition, treatment temperature is not particularly limited, it is preferably set to 30~85 DEG C.

Etching process process

For the stainless steel plate prepared as described above or implement at above-mentioned pretreated stainless steel plate implementation etching Reason, forms defined concaveconvex structure on the surface of stainless steel plate.

Here, etching process is not particularly limited, above-mentioned concaveconvex structure, is preferably immersed in containing hydrofluoric acid in order to obtain In solution, such as hydrofluoric acid aqueous solution, nitric hydrofluoric acid aqueous solution (the nitration mixture aqueous solution of hydrofluoric acid and nitric acid).

Here, the concentration of hydrofluoric acid is preferably the range of 1~200g/L.When less than 1g/L, etching power is insufficient, therefore, difficult To obtain desired concaveconvex structure.On the other hand, when the concentration of hydrofluoric acid is more than 200g/L, etch effect saturation.In addition, waste liquid Processing cost increases, and safety is also led to the problem of.Preferably 10g/L or more.Additionally, it is preferred that being 150g/L or less.

It should be noted that nitric acid can also be contained other than hydrofluoric acid.By containing nitric acid, bumps can be promoted The formation and passivation of structure.Thereby, it is possible to shorten aftermentioned stainless steel surface in the form of other than metal existing for Cr Concentration in the processing time.The range that the concentration of preferred nitric acid is 1~100g/L.

But concentration of nitric acid it is excessively high when, be passivated excessively carry out, it is difficult to obtain desired concaveconvex structure, it is therefore preferable that setting For hydrofluoric acid concentration > concentration of nitric acid.

In addition, in the solution containing hydrofluoric acid, if inorganic acid as sulfuric acid, hydrochloric acid other than hydrofluoric acid and nitric acid When (hereinafter also referred to other inorganic acids) add up to 10g/L or less, then it can also contain.However, it is preferred to which it is dense to be set as hydrofluoric acid Spend (total) concentration of other inorganic acids of >.

In addition, the treatment temperature and processing time when etching process are not particularly limited, it is preferably respectively set as 30~60 DEG C, 1~600 second.The preferred processing time is 30 seconds or more.In addition, more preferably the processing time is 300 seconds or less.

The surface of stainless steel plate in the form of other than metal existing for Cr concentration process

Then, the stainless steel for implementing etching process as described above is implemented other than the surface of stainless steel plate is with metal Form existing for Cr concentration (the hereinafter also referred to concentration of Cr).Thereby, it is possible to improve the table in stainless steel plate Face in the form of other than metal existing for Cr atomic concentration of the atomic concentration relative to Fe existing in the form of other than metal Ratio ([Cr]/[Fe]).

In addition, the concentration as Cr, impregnation in the solution with oxidisability, the stainless steel can be enumerated Electrolysis processing in the potential range that plate is passivated etc..

Here, the solution with oxidisability can enumerate aqueous solution of nitric acid, aqueous hydrogen peroxide solution.It should be noted that The dip time the long more the Cr in passivating film is promoted to be concentrated, and still, the effect is saturated when too long, and productivity reduces, therefore, It is preferably set to 2 hours (120 minutes) below.Lower limit is not particularly limited, is preferably set to 1 minute or more.More preferably It is 5 minutes or more.

It should be noted that the concentration of nitric acid is preferably set to 10~400g/L in the case where using aqueous solution of nitric acid.Separately Outside, treatment temperature is not particularly limited, and is preferably set to 30~60 DEG C.

In addition, current potential to be adjusted to the potential range being passivated to stainless steel plate when electrolysis processing.Particularly preferably The ingredient dissolution and the undissolved potential range of Cr being set as other than the Cr such as Fe, Ni contained in steel.

It should be noted that the potential range (passive state region) that stainless steel plate is passivated is also according to used electrolysis Liquid, stainless steel plate change at being grouped as, it is therefore preferable that be adjusted every time.For example, water-soluble using 50g/L nitric acid In the case where liquid, preferably implement electrolysis processing in the range of current potential is 0.4~0.8V (vs.Ag/AgCl).

In addition, electrolysis time it is more long promote surface of steel plate in the form of other than metal existing for Cr concentration, but mistake The effect is saturated when long, and productivity reduces.Therefore, electrolysis time be preferably set to 1 minute or more and 2 hours (120 points Clock) below.Preferred electrolysis time is 5 minutes or more.