JP7282103B2 - Stainless steel plate carbon composite material and its use, etc. - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stainless steel plate carbon composite material, a fuel cell separator, cell and stack using the composite material, an electrochemical hydrogen compressor separator and an electrochemical hydrogen compressor using the composite material, and a stainless steel plate. .

In recent years, attention has been paid to fuel cells from the viewpoint of environmental conservation. Taking a polymer electrolyte fuel cell as an example, an example of a fuel cell and a fuel cell separator is shown in FIGS. 5 and 6(a) and (b).
Here, FIG. 5 is an exploded view showing the structure of a unit cell constituting the fuel cell 17, and FIG. 6 is a view showing the structure of the fuel cell separator 5 shown in FIG. 6(a) is a plan view, and FIG. 6(b) is a cross-sectional view taken along line XY in FIG. 6(a).

The polymer electrolyte fuel cell 17 is a stack in which several tens to several hundreds of structures 10, which are unit cells, are stacked. In configuration 10, an MEA (membrane electrode assembly) consisting of a solid polymer electrolyte membrane 6, an anode (fuel electrode) 7, and a cathode (oxidant electrode) 8 is combined with two fuel cell separators 5 is sandwiched through the gasket 9. By supplying a fuel gas (hydrogen gas) as a fluid to the anode 7 and an oxidizing gas (oxygen gas) as a fluid to the cathode 8, current is extracted from an external circuit. As illustrated in FIGS. 6A and 6B, the fuel cell separator 5 has a plurality of gas supply/discharge grooves 11 and gas supply/discharge grooves 11 on one or both sides of a thin plate-like body. It has an opening 12 for supplying fuel gas or oxidant gas to the groove 11 and a fixing hole 13 for juxtaposing the MEA. The fuel cell separator 5 has the role of separating the fuel gas and the oxidizing gas flowing in the fuel cell so that they do not mix, and also transmits the electrical energy generated in the MEA to the outside and the heat generated in the MEA to the outside. It plays an important role in dissipating heat.

Therefore, the characteristics required for fuel cell separators are long-term durability (corrosion resistance) under the usage environment (high temperature, corrosiveness, low pH, etc.) inside the fuel cell, It has low resistance and excellent conductivity (high conductivity, low contact resistance), and it has gas impermeability to completely separate the fuel gas and the oxidant gas on both sides. In addition, assuming that it will be mounted on a vehicle, it is required to have strength and flexibility (flexibility) that will not crack even when bolts are tightened during assembly or vibration.

Conventionally, various studies have been made on the development of such separators. It has been confirmed that a stainless steel plate carbon composite material, in which a carbon layer composed of carbon powder and resin powder is laminated on at least one side of a metal (stainless steel) base material, is excellent in corrosion resistance, conductivity, flexibility, and the like. (See Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2017-071218 JP 2017-071219 A JP-A-2004-232074

Particularly in the field of fuel cells for automobiles, there is a demand for further thinning and high performance of separators, and further improvement is demanded for each performance of separators. In the stainless steel plate carbon composite material described in Patent Documents 1 and 2, a carbon layer made of a carbonaceous material such as graphite powder and a matrix resin is laminated on a substrate. In order to further improve the conductivity, for example, measures such as increasing the blending ratio of the carbonaceous material in the carbon layer can be considered. However, there is concern that the proportion of the carbonaceous material affects the adhesion of the carbon layer to the substrate, the compactness (density), the surface flatness, and the like. There is a limit to the improvement of conductivity by improving the carbon layer.

The inventors of the present application thought that it was necessary to improve stainless steel, which is the base material, in order to further improve separator performance such as conductivity. A study focused on the composition of stainless steel led to the following findings.
In the stainless steel plate carbon composite materials described in Patent Documents 1 and 2, stainless steel with a high chromium (Cr) content (16.00% by mass or more) is used mainly to ensure corrosion resistance. When the Cr content is high, a thick and dense oxide film tends to be formed on the surface layer, which tends to lower the electrical conductivity. Moreover, such a thick and dense oxide film is highly stable and may weaken the bond with other materials on the stainless steel surface. If the bond is weak, the workability of the substrate (that is, the adhesion between the substrate and the carbon layer. Unless otherwise specified, in the present application, the adhesion between the substrate and the carbon layer is referred to as the “workability” of the substrate. ".) may become insufficient. Thus, the inventors thought that the stainless steel plate carbon composite materials described in Patent Documents 1 and 2 have room for further improvement in conductivity and workability.
Based on this concept of conductivity and workability (adhesion of the carbon layer), we have developed a composite material in which a carbon layer containing a carbonaceous material and a matrix resin is laminated on a base material of stainless steel containing low chromium. We created a material and examined its conductivity and workability. This composite material has improved electrical conductivity and workability (adhesion to the carbon layer). However, it was unexpectedly found that this composite material has another problem that the matrix resin in the carbon layer is deteriorated and the corrosion resistance is lowered.

Therefore, the inventors further investigated the cause of the deterioration of the matrix resin in the composite material with the carbon layer using stainless steel with a low chromium content as the base material. As a result, quite unexpectedly, the copper (Cu) content in the surface layer region of the stainless steel substrate (including the oxide film layer that naturally forms on the stainless steel surface) is much higher than in other regions. It was found to be higher (concentrated). It was found that the Cu concentrated on the surface layer causes deterioration of the matrix resin. That is, it was found that the deterioration of the matrix resin is due to so-called copper damage (here, "enriched in the surface layer" means that the content in the surface layer is higher than in other areas of the steel) . Although the detailed principle of Cu concentration on the surface layer of the stainless steel base material is not clear, as far as it is confirmed in the examples and comparative examples described later, it is contained in the stainless steel base material from the beginning. It is presumed that this is due to the content of Cu that causes the deterioration and the removal of the oxide film on the surface of the base material (washing treatment with acid) that is carried out in the subsequent manufacturing process. Furthermore, surprisingly, it was found that the content of Cu concentrated in the base material surface layer also contributed to the conductivity as a separator (stainless steel plate carbon composite material). Furthermore, not only Cu but also carbon (C) is concentrated in the base material surface layer, and this concentrated C content also contributes to the adhesion between the base material and the carbon layer. There was found. Based on these findings, by setting the stainless steel base material to a specific chemical composition and by setting the contents of Cu and C concentrated in the surface layer of the base material within a specific range, corrosion resistance is satisfied while The inventors have found that a stainless steel plate carbon composite material having good electrical conductivity and workability can be obtained, and completed the present invention.
Incidentally, Cu enrichment itself in the surface layer of stainless steel has already been shown in Patent Document 3. However, Patent Document 3 does not disclose lamination of carbon layers having a matrix resin, and no consideration is given to deterioration of the matrix resin due to concentrated Cu. That is, in the field of fuel cell separators, copper damage caused by the combined use of such a base material and a carbon layer is not recognized as a problem. The development of a stainless steel plate carbon composite material with good corrosion resistance has not been made so far.

An object of the present invention is to provide a stainless steel plate carbon composite material which is excellent in electrical conductivity, corrosion resistance and workability (adhesion between the base material and the carbon layer).
Another object of the present invention is to provide a fuel cell separator, cell and stack using such a stainless steel plate carbon composite material.
Another object of the present invention is to provide a separator for an electrochemical hydrogen compressor and an electrochemical hydrogen compressor using such a stainless steel carbon composite material.
Further, another object of the present invention is to provide a stainless steel plate that can be applied to the above stainless steel plate carbon composite material, a fuel cell separator, a cell, a stack, and the like using the same.

The gist of the present invention is as follows.
(1) A stainless steel plate carbon composite material in which a carbon layer containing a carbonaceous material and a matrix resin made of a thermoplastic resin or a thermosetting resin is laminated on at least one side of a plate-shaped base material made of stainless steel,
The base material contains at least 0.001 to 0.2% by mass of carbon (C), 9.0% to 16.0% by mass of chromium (Cr), and 0.005 to 1% of copper (Cu). .0% by mass, and in quantitative elemental analysis in the thickness direction of the substrate surface layer by glow discharge emission spectrometry, the Cu content in the measurement range defined in (i) below is 0.010 to 0.30 A stainless steel plate carbon composite material having a C content of 2 to 15% by mass, and a C content in the measurement range defined in (ii) below.
(i) The substrate center side where the peak intensity of 1/50 of the peak intensity (maximum peak intensity) at this position P is measured across the position P where the peak intensity of Cu measured on the substrate surface layer is maximum and a position D2 where the same peak intensity as this position D1 is measured on the substrate surface side.
(ii) A range connecting the position D3 on the substrate center side where the intensity of 1/50 of the peak intensity of C at the position P is measured, and the position D2 on the substrate surface side, with the position P interposed therebetween.
(2) The stainless steel plate carbon composite material according to (1), wherein the substrate has the following chemical composition.
C: 0.001 to 0.2% by mass,
Si: 0.01 to 2.0% by mass,
Mn: 0.01 to 2.5% by mass,
Al: 0.001 to 0.5% by mass,
Cr: 9.0% by mass or more and less than 16.0% by mass,
Cu: 0.005 to 1.0% by mass,
P: 0.1% by mass or less,
S: 0.01% by mass or less,
Ni: 0 to 0.3% by mass,
Ti: 0 to 2.0% by mass,
Mo: 0 to 3.0% by mass,
V: 0 to 1.0% by mass,
Nb: 0 to 1.0% by mass,
W: 0 to 1.0% by mass,
Ta: 0 to 1.0% by mass,
Sb: 0 to 1.0% by mass,
Pb: 0-1.0% by mass, and balance: Fe and impurities.
(3) A fuel cell separator using the stainless steel plate carbon composite material according to (1) or (2) above.
(4) A fuel cell comprising the fuel cell separator according to (3) above.
(5) A fuel cell stack comprising the fuel cell according to (4).
(6) A separator for an electrochemical hydrogen compressor using the stainless steel plate carbon composite material according to (1) or (2) above.
(7) An electrochemical hydrogen compressor comprising the separator for an electrochemical hydrogen compressor according to (6) above.
(8) A stainless steel plate,
Contains at least 0.001 to 0.2 mass% of carbon (C), 9.0 mass% to less than 16.0 mass% of chromium (Cr), and 0.005 to 1.0 mass% of copper (Cu) In addition, in quantitative elemental analysis in the thickness direction of the surface layer by glow discharge emission spectrometry, the Cu content in the measurement range defined in (i') below is 0.008 to 0.28% by mass, and the following A stainless steel plate having a C content of 1.8 to 13.5% by mass in the measurement range defined in (ii').
(i') The peak intensity of 1/50 of the peak intensity (maximum peak intensity) at this position P' is measured across the position P' where the peak intensity of Cu measured on the surface layer of the steel sheet is maximum. A range connecting a position D1′ on the center side of the steel plate and the surface of the steel plate.
(ii') A range connecting the surface of the steel sheet and a position D3' on the center side of the steel sheet where the strength of 1/50 of the peak strength of C at the position P' is measured across the position P'.

According to the present invention, it is possible to provide a stainless steel plate carbon composite material which is excellent in both electrical conductivity, corrosion resistance and workability (adhesion between the base material and the carbon layer). Since the stainless steel plate carbon composite material according to the present invention has such properties, it can be suitably used as separators, cells and stacks for fuel cells, separators for electrochemical hydrogen compressors, and electrochemical hydrogen compressors. obtain.

FIG. 1 is a schematic explanatory diagram showing an outline of the procedure for glow discharge optical emission spectroscopy (GDS) in this embodiment. FIG. 2 is a schematic illustration of a molding method for manufacturing a carbon layer or a stainless steel plate carbon composite. FIG. 3 is a schematic illustration of a method of laminating a carbon layer, an adhesive layer, and a stainless steel plate-like substrate in the production of the stainless steel plate carbon composite material of the present invention. FIG. 4 is a schematic illustration of a method for measuring contact resistance. FIG. 5 is an exploded view showing an example of the configuration of a unit cell that constitutes the fuel cell. FIG. 6(a) is a plan view showing an example of a fuel cell separator, and FIG. 6(b) is a sectional view taken along line XY in FIG. 6(a). FIG. 7 is a schematic illustration of another method of measuring contact resistance. FIG. 8 is an exploded view showing an example of the configuration of an electrochemical hydrogen compressor.

Hereinafter, a stainless steel plate carbon composite material and a method for producing the same according to embodiments of the present invention will be described in detail.
The stainless steel plate carbon composite material of the present embodiment is obtained by laminating a carbon layer containing a carbonaceous material and a matrix resin made of a thermoplastic resin or a thermosetting resin on at least one side of a plate-shaped base material made of stainless steel. is. The plate-shaped substrate contains at least predetermined amounts of carbon (C), chromium (Cr), and copper (Cu), and in quantitative elemental analysis in the thickness direction of the surface layer of the substrate by glow discharge emission spectrometry, Cu and C have a predetermined content (enriched).

<Plate-shaped substrate>
The stainless steel plate-shaped substrate (stainless steel plate, hereinafter sometimes simply referred to as “plate-shaped substrate” or “substrate”) used in the present embodiment contains at least carbon (C), Although there is no particular limitation as long as it contains predetermined amounts of chromium (Cr) and copper (Cu), one having a chemical composition described later is preferably used. For example, steel having such a chemical composition is melted in a vacuum furnace, cast into an ingot, and then hot forged, hot rolled, annealed, and cold rolled to obtain a stainless steel plate. . A known method can be used for these processing conditions. Examples of commercially available products include SUS409, SUS405, SUS410L and SUS429 as ferritic stainless steels, and SUS403, SUS410 and SUS420 as martensitic stainless steels. Such a plate-shaped base material made of stainless steel (stainless steel plate) can be used as an intermediate material for producing a stainless steel plate carbon composite material, or can be used alone.

Each element that is essential or preferably contained in the substrate will be described below. In addition, all "%" of content means "mass %."

C: 0.001 to 0.2% by mass
Carbon (C) is a solid-solution strengthening element and contributes to improving the strength (for example, tensile strength) of stainless steel. In addition, as will be described later, it is believed to be an element that is concentrated in the base material surface layer and contributes to the improvement of adhesion to the carbon layer. When the C content is less than 0.001% and is too low, it is difficult to obtain the above effects of developing strength and thickening the base material surface layer. On the other hand, if the C content exceeds 0.2% and is too high, a large number of carbides are formed during the manufacturing process of the base material, and these carbides may become starting points of fracture, deteriorating the formability of the stainless steel. . A preferred lower limit for the C content is 0.002% by mass, and a more preferred lower limit is 0.004%. A preferred upper limit of the C content is 0.15%, and a more preferred upper limit is 0.1%.

Si: 0.01 to 2.0% by mass
Silicon (Si) is an element effective for deoxidation. If the Si content is less than 0.01% and is too low, deoxidation may be insufficient. On the other hand, if the Si content exceeds 2.0% and is too high, the formability of the stainless steel may deteriorate. A preferred lower limit for the Si content is 0.02%, and a more preferred lower limit is 0.04%. A preferred upper limit of the Si content is 1.5%, and a more preferred upper limit is 1.0%.

Mn: 0.01 to 2.5% by mass
Manganese (Mn) has the effect of suppressing deterioration of hot workability due to sulfur (S). Mn also has the effect of deoxidizing stainless steel. If the Mn content is less than 0.01% and is too low, these effects are difficult to obtain. On the other hand, if the Mn content exceeds 2.5% and is too high, precipitation of intermetallic compound phases such as the σ phase is promoted, and the structural stability is lowered, and the toughness and ductility of the stainless steel may be lowered. be. A preferred lower limit for the Mn content is 0.02%, and a more preferred lower limit is 0.03%. The preferred upper limit of the Mn content is 2.0%, and the more preferred upper limit is 1.5%.

Al: 0.001 to 0.5% by mass
Aluminum (Al) is an element effective for deoxidation. If the Al content is less than 0.001% and is too low, it is difficult to obtain the deoxidizing effect. On the other hand, if the Al content exceeds 0.5% and is too high, the cleanliness of the steel is lowered, and the formability and ductility of the stainless steel are lowered. A preferred lower limit for the Al content is 0.002%, and a more preferred lower limit is 0.005%. A preferable upper limit of the Al content is 0.4%, and a more preferable upper limit is 0.3%.

Cr: 9.0% by Mass or More and Less than 16.0% by Mass Chromium (Cr) is an effective element for ensuring the corrosion resistance of stainless steel. If the Cr content is less than 9.0% and is too low, it may be difficult to form a passive film, and corrosion resistance may not be ensured. On the other hand, if the Cr content is 16.0% or more, which is too high, the passivation film formed is thick, and the electrical conductivity of the stainless steel may decrease. Furthermore, since such a thick passive film is highly stable, it becomes difficult to form a strong bond with other materials on the outermost surface of the steel material, and there is a risk that workability (adhesion with the carbon layer) will decrease. There is In the present embodiment, stainless steel with a lower Cr content than conventional stainless steel is used as the base material, but the corrosion resistance can be compensated by having a carbon layer, which will be described later. A preferred lower limit for the Cr content is 9.2%, and a more preferred lower limit is 9.5%. A preferable upper limit of the Cr content is 15.5%, and a more preferable upper limit is 15.0%.

Cu: 0.005 to 1.0% by mass
Copper (Cu) is generally an effective element for improving strength and corrosion resistance. In the present embodiment, if the Cu content in the substrate is less than 0.005% and is too low, the above general effects are difficult to obtain, and the Cu content that is concentrated in the surface layer described later is reduced. Therefore, there is a possibility that the effect of improving conductivity cannot be obtained. On the other hand, if the Cu content exceeds 1.0% by mass and is too high, the hot workability of the stainless steel may deteriorate, and the Cu content that is concentrated in the surface layer, which will be described later, becomes excessive. In addition, the matrix resin in the carbon layer laminated on the base material may be deteriorated (copper damage), thereby reducing the corrosion resistance. A preferred lower limit for the Cu content is 0.006%, and a more preferred lower limit is 0.008%. A preferable upper limit of the Cu content is 0.95%, and a more preferable upper limit is 0.90%.

P: 0.1 mass % or less Phosphorus (P) is an impurity. Since P segregates at grain boundaries during solidification and embrittles the grain boundaries, its content is preferably 0.1% or less, more preferably 0.04% or less, and still more preferably 0.01% or less. , and the lower the better.

S: 0.01% mass or less Sulfur (S) is an impurity. S also segregates at grain boundaries during solidification and embrittles the grain boundaries, so the content is preferably 0.01% or less, more preferably 0.004% or less, and still more preferably 0.001%. or less, the lower the better.

Ni: 0 to 0.3% by mass
Nickel (Ni) is not essential to be added, but it has the effect of improving the corrosion resistance and toughness of stainless steel, so it may be included if necessary. On the other hand, if the Ni content exceeds 0.3% and is too high, it tends to form a two-phase structure of ferrite and austenite. may be insufficient. A preferable upper limit of the Ni content is 0.25%, and a more preferable upper limit is 0.2%. The preferable lower limit of the Ni content for obtaining the effects of corrosion resistance and toughness is 0.001%, and the more preferable lower limit is 0.01%.

Ti: 0 to 2.0% by mass
Titanium (Ti) is not essential to be added, but it is a C and N stabilizing element that can react with C and N to form carbides and nitrides in steel, so it is included as necessary. You may let On the other hand, if the Ti content exceeds 2.0% and is too high, there is a risk of deteriorating formability. A preferred upper limit of the Ti content is 1.0%, and a more preferred upper limit is 0.5%. The preferred lower limit of the Ti content to obtain the stabilizing effect is 0.001%, and the more preferred lower limit is 0.005%.

Mo: 0 to 3.0% by mass
Molybdenum (Mo) is not essential to be added, but it is an element capable of increasing the corrosion resistance of stainless steel, and may be included as necessary. On the other hand, if the Mo content exceeds 3.0% and is too high, it is difficult to avoid precipitation of intermetallic compounds such as the σ phase, which may cause embrittlement of the steel and make production difficult. A preferred upper limit for the Mo content is 1.5%, and a more preferred upper limit is 1.0%. A preferable lower limit of the Mo content to obtain the above corrosion resistance effect is 0.001%, and a more preferable lower limit is 0.005%.

V: 0 to 1.0% by mass
Vanadium (V) is not essential to be added, but it is an effective element for improving the corrosion resistance of stainless steel, and may be included if necessary. On the other hand, if the V content exceeds 1.0% and is too high, the workability may deteriorate. A preferred upper limit of the V content is 0.8%, and a more preferred upper limit is 0.5%. A preferable lower limit of the V content to obtain the above corrosion resistance effect is 0.001%, and a more preferable lower limit is 0.002%.

Nb: 0 to 1.0% by mass
Niobium (Nb) is not essential to be added, but like Ti, it is a C and N stabilizing element that can react with C and N in steel to form carbides and nitrides. may be included as appropriate. On the other hand, if the Nb content exceeds 1.0% and is too high, the moldability may deteriorate. A preferred upper limit of the Nb content is 0.8%, and a more preferred upper limit is 0.5%. A preferable lower limit of the Nb content to obtain the stabilizing effect is 0.0001%, and a more preferable lower limit is 0.0005%.

W: 0 to 1.0% by mass
Tungsten (W) is not essential to be added, but is an element capable of enhancing corrosion resistance, and may be included as necessary. On the other hand, if the W content exceeds 1.0% and is too high, the moldability may deteriorate. A preferred upper limit of the W content is 0.8%, and a more preferred upper limit is 0.5%. A preferable lower limit of the W content for obtaining the above corrosion resistance effect is 0.001%, and a more preferable lower limit is 0.002%.

Ta: 0 to 1.0% by mass
Although addition of tantalum (Ta) is not essential, it is an element capable of improving corrosion resistance, and may be included as necessary. On the other hand, if the Ta content exceeds 1.0% and is too high, the moldability may deteriorate. A preferred upper limit of the Ta content is 0.8%, and a more preferred upper limit is 0.5%. A preferable lower limit of the Ta content for obtaining the corrosion resistance effect is 0.0001%, and a more preferable lower limit is 0.0002%.

Sb: 0 to 1.0% by mass
Antimony (Sb) is not essential to be added, but is an element capable of improving corrosion resistance, and may be included if necessary. On the other hand, if the Sb content exceeds 1.0% and is too high, the moldability may deteriorate. A preferred upper limit of the Sb content is 0.5%, and a more preferred upper limit is 0.2%. A preferable lower limit of the Sb content to obtain the above corrosion resistance effect is 0.0001%, and a more preferable lower limit is 0.0002%.

Pb: 0 to 1.0% by mass
Addition of lead (Pb) is not essential, but it is an element capable of improving corrosion resistance, and may be contained as necessary. On the other hand, if the Pb content exceeds 1.0% and is too high, the moldability may deteriorate. A preferred upper limit of the Pb content is 0.5%, and a more preferred upper limit is 0.2%. A preferable lower limit of the Pb content for obtaining the above corrosion resistance effect is 0.0001%, and a more preferable lower limit is 0.0002%.
The balance of the chemical composition of the substrate in this embodiment consists of Fe and impurities. Here, the impurities are those that are inevitably mixed from ore, scrap, or the manufacturing environment as raw materials when industrially manufacturing the base material, and are within a range that does not adversely affect the present embodiment. permissible in

In this embodiment, the surface of the stainless steel plate-like substrate inevitably has an oxide film layer (usually about 6 nm or more and 25 nm or less) formed after removing the passivation film. In the region of the surface layer of the substrate including the oxide film layer, it was confirmed that the contents of Cu and C elements are high, although the details of the form as a compound are not necessarily clear. That is, it was confirmed that these elements were concentrated. The content of Cu and C in the base material surface layer is determined by [1] for stainless steel plate carbon composites, a method of analyzing from the surface of the base material exposed after removing only the carbon layer, [2] before forming the carbon layer For a single stainless steel plate, it can be measured by a method of analyzing from the surface.

First, [1] stainless steel plate carbon composite material will be described. In the stainless steel plate carbon composite material of the present embodiment, the Cu content in the surface layer of the substrate is 0.01 to 0.3% by mass. By setting it as such Cu content, electroconductivity improves (contact resistance reduces). If the Cu content is less than 0.01% by mass, the effect of improving conductivity is poor. On the other hand, when the Cu content exceeds 0.3% by mass, especially when the base material is made of stainless steel with a low Cr content as in the present embodiment, the Cu concentrated in the surface layer causes the carbon layer to Matrix resin deteriorates and corrosion resistance decreases (copper damage). A preferable lower limit of the Cu content is 0.05% by mass, and a preferable upper limit is 0.2% by mass. In the stainless steel plate carbon composite material, as a manufacturing method for making the Cu content of the base material surface layer within the above range, the base material having the above Cu content is used, and the surface layer is subjected to the acid cleaning treatment described later. Elements other than Cu should be reduced.

Furthermore, in the stainless steel plate carbon composite material of the present embodiment, the C content in the surface layer of the substrate is 2% by mass or more and 15% by mass or less. By setting it as such C content, workability (adhesion of a base material and a carbon layer) improves. If the C content is less than 2% by mass, the effect of improving workability is poor. On the other hand, when the C content exceeds 15% by mass, the workability improvement effect is saturated. A preferable lower limit of the C content is 3.5% by mass, and a preferable upper limit is 10% by mass. In the stainless steel plate carbon composite material, as a manufacturing method for making the C content of the base material surface layer within the above range, in the acid cleaning treatment described later, the cleaning time may be appropriately adjusted without excessively lengthening.

Here, in the present embodiment, the Cu and C concentrations in the surface layer of the plate-like substrate (that is, the range of about 100 nm including the oxide film layer) are measured by glow discharge optical emission spectrometry (GDS). is. Quantitative analysis of a desired element is performed by GDS from information in the thickness (depth) direction of the base material and the luminescence intensity (peak intensity) of the desired element obtained in the process while scraping the surface of the base material, etc., which is a sample. It can be carried out. When measuring the Cu and C concentrations in the substrate surface layer of the stainless steel plate carbon composite material of [1] above, the analysis is performed from the substrate surface exposed after removing only the carbon layer. In this case, it is difficult to uniformly determine the surface of the base material after removing the carbon layer, and especially for the C element to be measured, it is difficult to distinguish between the C element in the carbon layer and the one concentrated on the surface layer of the base material. For reasons such as difficulty, as shown in FIG. 1, one carbon layer is first removed (FIG. 1A), and the base material is gradually cut from the side where the carbon layer is removed. , When the base material reaches a certain thickness, the GDS measurement is performed from the cut surface side (that is, the center side in the thickness direction of the base material) toward the opposite surface layer side of the base material (Fig. 1B), which will be described later. It is possible to specify the measurement range (positions P, D1, D2 and D3) and measure the content of the element of interest (FIG. 1C). For stainless steel plate carbon composite materials, by performing pretreatment and GDS measurement from the side opposite to the surface layer side of the base material to be measured in this way, measurement errors due to peeling of the carbon layer can be minimized. can be ruled out.

In the method of measuring the Cu and C contents in the base material surface layer of the stainless steel plate carbon composite material of [1], specifically, the following (i) and (ii) are preferably performed. (i) Among Cu and C to be measured, Cu is not contained in the carbon layer but is contained only in the base material. Therefore, it is preferable to grasp the distribution of Cu first. First, the position (P) in the thickness direction of the base material where the peak intensity of Cu measured on the surface layer of the base material to be measured is the maximum is grasped, and in the thickness region before and after sandwiching this position P, the distribution of Cu is Positions where measurement is almost impossible are specified, and the ratio of the integrated Cu content to the total element content in these thickness ranges (measurement ranges) is determined. The ratio obtained in this manner can be used as the Cu content (% by mass) of the substrate surface layer in the stainless steel plate carbon composite material of the present embodiment. The position where the Cu distribution is hardly measured is defined as the position where the peak intensity of 1/50 of the peak intensity (maximum peak intensity) at the position P is measured. D1 is the position where almost no Cu distribution is measured on the center side in the thickness direction of the base material, D2 is the position where almost no Cu distribution is measured on the opposite side of the base material surface layer, and the thickness range from D1 to D2 is It can be a "measuring range" for the Cu content.
(ii) For the measurement of the content of the C element, assuming that the position P where the peak intensity of the Cu is the maximum is the position where the distribution of C derived from the substrate is the maximum, this position P is set as the starting point, and the base is A range (A) whose end point is the position where the C concentration is 1/50 of the C concentration at position P on the cut surface side of the material (base material center side) (this is called D3), and the position P is the starting point can be used as the "measurement range" for the C content. In the same manner as the measurement of the Cu element in (i), the ratio of the integrated C content to the total elemental content in this measurement range is obtained. The ratio obtained in this manner can be used as the C content (% by mass) of the substrate surface layer in the stainless steel plate carbon composite material of the present embodiment.

Regarding the method of measuring the Cu and C contents of the base material surface layer of the stainless steel sheet alone before the carbon layer is formed in [2] above, measurement is performed by glow discharge optical emission spectrometry (GDS) in the same manner as in [1]. conduct. However, in the case of [2], the operation of removing the carbon layer is unnecessary, and the GDS measurement is started directly from the surface (outermost surface) of the substrate. Specifically, the following (i') and (ii') are performed.
(i') For Cu, as in the method [1] above, the position (P') in the thickness direction of the base material at which the peak intensity of Cu measured on the surface layer of the base material is maximized is first grasped, and this In the region on the center side of the substrate thickness direction from the position P ', the position D1 ' where the distribution of Cu is hardly measured [that is, the peak intensity (maximum peak intensity) at the position P ' 1/50 of the peak intensity is measured position] is specified. Then, the ratio of the integrated Cu content to the total element content in the thickness range (measurement range) from the surface (outermost surface) of the substrate to the D1 ' is calculated as the substrate in the case of [2] of the present embodiment. It can be the Cu content (% by mass) concentrated in the surface layer.

(ii') Regarding the measurement of the content of the C element, as in the method of [1] above, first, the position P' in the thickness direction of the base material at which the peak intensity of the Cu is maximum is determined from the base material. Assuming that the distribution of C is the maximum position, this position P' is set as the starting point, and the position where the C concentration is 1/50 of the C concentration at the position P' on the center side in the thickness direction of the base material (this is D3' ) as the end point and the total thickness range of the thickness range (B ') from the substrate surface (outermost surface) to the position P ' for the C content " measurement range”. In the same manner as the Cu element measurement, the ratio of the integrated C content in this measurement range to the total element content is obtained. The ratio obtained in this manner can be used as the C content (% by mass) of the base material surface layer in the case of a single base material made of a stainless steel plate.

Then, from the results obtained by the method [2], in the surface layer of the stainless steel plate before forming the carbon layer, the Cu content is 0.008 to 0.28% by mass, and the C content is 1.8 to 13.5. % by mass. A preferable lower limit of the Cu content is 0.01% by mass, and a preferable upper limit is 0.25% by mass. A preferable lower limit of the C content is 3.0% by mass, and a preferable upper limit is 12% by mass. In order to set the Cu content in the surface layer within the above range, the elements other than Cu in the surface layer may be reduced by subjecting the stainless steel sheet having the Cu content described above to an acid cleaning treatment, which will be described later. In order to make the C content of the surface layer within the above range, it is necessary to appropriately adjust the cleaning time in the acid cleaning treatment to be described later without excessively lengthening the cleaning time.
By using such a stainless steel plate as a base material and forming a carbon layer on the surface thereof, the stainless steel plate carbon composite material of the embodiment of the present invention can be produced.

As is clear from the results of Examples described later, the content of Cu and C concentrated in the surface layer of the base material is higher in the case of [1] than in the case of [2]. Regarding the reason why the numerical values are uniformly high, in the method [1], since the measurement is performed in the state where the carbon layer exists on one side of the substrate, the presence of the carbon layer causes the It is presumed that the slight difference between the position D2 in the case of (2) and the position (uppermost surface of the base material) in the case of (2) causes a slight difference in the "measurement range" between the two.

In the present embodiment, since the plate-like substrate has such a surface layer state, the contact resistance is preferably 10 mΩ·cm ² or less, more preferably 5 mΩ·cm ² or less. More preferably, the contact resistance is 3 mΩ·cm ² or less, and the contact resistance does not substantially change even after 30 days.

The thickness of the stainless steel plate-like substrate is not particularly limited, but is preferably 10 μm or more and 150 μm or less, more preferably 20 μm or more and 70 μm or less. If the thickness of the plate-shaped substrate is less than 10 μm, the mechanical strength may be insufficient, and if it exceeds 150 μm, problems may arise in terms of softness and flexibility.

<Carbon layer>
The carbon layer laminated on the surface of the plate-like substrate contains a carbonaceous material and a matrix resin made of a thermoplastic resin or a thermosetting resin. The volume ratio (CA/R) between the carbonaceous material (CA) and the matrix resin (R) in the carbon layer is preferably 6/4 to 9/1, more preferably 7/3 to 8/2. be. The thickness of the carbon layer is preferably 0.05 mm or more and 2.0 mm or less, more preferably 0.1 mm or more and 1.0 mm or less. If the volume ratio (CA/R) of the carbonaceous material (CA) and the matrix resin (R) is less than 6/4 and the ratio of the carbonaceous material is too low, the conductivity may decrease. If the ratio is more than 9/1, the ratio of the matrix resin is too low, which may lead to poor flexibility, flexibility and corrosion resistance. If the thickness of the carbon layer is less than 0.05 mm, corrosion may start from even a slight crack in the carbon layer.

Here, the carbonaceous material forming the carbon layer may be any material as long as it has electrical conductivity, and its properties and the like are not limited. As the carbonaceous material, for example, one or more selected from powders such as natural graphite powder, artificial graphite powder, expanded graphite powder, expanded graphite powder, flake graphite powder, spherical graphite powder, etc. can be mentioned. Preferably, at least expanded graphite powder and/or expanded graphite powder is included in terms of flexibility and conductivity. In that case, the content of the expanded graphite powder and/or the expanded graphite powder is preferably 4% by volume or more and less than 51% by volume in the mixed powder of the carbonaceous powder and the resin powder, and 5% by volume or more and less than 21% by volume. more preferred. If the content is less than 4% by volume, the flexibility may become low. On the other hand, if the content is 51% by volume or more, the resin that originally contributes to the adhesion between the particles or between the particles and the metal plate cannot function well. Otherwise, contact resistance may increase. In this range, as for the mass content of the expanded graphite powder and/or the expanded graphite powder in the carbonaceous powder, the true specific gravity of the expanded graphite powder and/or the expanded graphite powder is 2.2 g, which is the same as that of the other graphite powder. /cm ³ , preferably 5% by mass or more and less than 73% by mass, more preferably 7% by mass or more and less than 30% by mass.
The particle size of the carbonaceous powder is represented by the value of D ₅₀ (cumulative 50% by volume diameter) calculated by a particle size analyzer of a laser diffraction particle size distribution analyzer (for example, "Mastersizer 2000" manufactured by Malvern). The average particle size is preferably 4 μm or more and 200 μm or less, more preferably 10 μm or more and 30 μm or less. If the average particle size is less than 4 μm, the resin has a large specific surface area, which makes it difficult to use the resin for adhesion between particles or a SUS plate, and there is a risk of poor flexibility. If the average particle size is larger than 200 μm, it is difficult to obtain a smooth surface when forming the carbon layer, and there is a possibility that the defect rate may increase.

Further, the properties and the like of the matrix resin forming the carbon layer are not limited. It may be a thermoplastic resin or a thermosetting resin. The thermoplastic resin can be selected according to the application and is not particularly limited, but is preferably polypropylene resin (PP), polyethylene resin (PE), polyamide resin (PA), polyphenylene sulfide resin ( PPS), polymethylpentene resin (PMP), polyetheretherketone resin (PEEK), polyphenylene ether resin (PPE), liquid crystal polymer resin (LCP), polyamideimide resin (PAI), polysulfone resin (PSU), polyethylene terephthalate resin (PET) and polybutylene terephthalate resin (PBT), or a mixture of two or more of them, and the thermosetting resin is selected according to the application. Any one or a mixture of two or more selected from the group consisting of phenolic resins and epoxy resins is preferable, although it is possible and not particularly limited.

Here, for polyolefin resins such as PP, PE, and PMP, it is also possible to use modified polyolefin resins modified by grafting part or all of unsaturated carboxylic acids or derivatives thereof to the polyolefin resins. . By using such a modified polyolefin resin, it is possible to improve the flexibility of the carbon layer and the carbon composite material of the stainless steel plate provided therewith, and to improve the adhesion to SUS and the adhesion to carbon particles. This is expected and preferable because it reduces the contact resistance. The graft amount (graft ratio) in the entire modified polyolefin resin is generally preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, and still more preferably 0.1 to 3%. % by mass. Specific examples of the unsaturated carboxylic acid or derivative thereof used for grafting onto the polyolefin resin before modification include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, and maleic anhydride. , Himic anhydride, 4-methylcyclohexe-4-ene-1,2-dicarboxylic anhydride, α-ethylacrylic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, endocis-bicyclo[2,2, 1] Hept-5-ene-2,3-dicarboxylic acid (nadic acid (trademark)), bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride, 1,2,3 , 4,5,8,9,10-octahydronaphthalene-2,3-dicarboxylic anhydride, 2-octa-1,3-diketospiro[4.4]non-7-ene, bicyclo[2.2. 1]hept-5-ene-2,3-dicarboxylic anhydride, maleopimaric acid, tetrahydrophthalic anhydride, x-methyl-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid anhydride, x-methyl-norbornen-5-ene-2,3-dicarboxylic anhydride (x indicates the substituted position of the methyl group), and norborne-5-ene-2,3-dicarboxylic anhydride, etc. can be used. Acid halides, amides, imides, esters and other derivatives of the above unsaturated carboxylic acids can also be used. Among these, unsaturated dicarboxylic acids and acid anhydrides thereof are preferred, and maleic anhydride and hymic acid anhydride are particularly preferred. Such unsaturated carboxylic acids or derivatives thereof can be used singly or in combination of two or more. Chlorine or bromine can be preferably used as the halogen group.

<Adhesive layer>
In the present embodiment, the surface of the stainless steel plate-shaped substrate and the carbon layer laminated on this surface may be bonded via an adhesive layer having a thickness of usually 0.1 μm or more and 10 μm or less. . The adhesive composition for forming such an adhesive layer is not particularly limited, but is preferably a modified polyolefin resin in which a part or all of an unsaturated carboxylic acid or derivative thereof is grafted onto a polyolefin resin. (for example, see JP-A-2005-146178), specifically, an adhesive composition containing an adhesive polyolefin resin (manufactured by Mitsui Chemicals, Inc., trade name: ADMER), unsaturated An adhesive composition containing a modified polyolefin resin graft-modified with a carboxylic acid (manufactured by Mitsui Chemicals, Inc., trade name: UNISTOL), and the like. An adhesive composition containing a modified polyolefin resin graft-modified with halogen (trade name: Toyotac, manufactured by Toyobo Co., Ltd.) can also be used. Isopropyl alcohol, phenol resin: product name: AH-1148 manufactured by Lignite Co., Ltd.), epoxy resin adhesive composition (product name: YSLV-80XY manufactured by Nippon Steel Chemical & Materials Co., Ltd.), and the like can also be used. If the layer thickness of the adhesive layer is less than 0.1 μm, the adhesive strength may decrease, and if it exceeds 10 μm, the electrical conductivity of the stainless steel plate carbon composite material produced may decrease.

<Production of stainless steel plate carbon composite material>
Regarding the method for producing the stainless steel plate carbon composite material of the present embodiment, a stainless steel plate-shaped substrate having the chemical composition and the Cu and C content in the surface layer as described above is prepared (substrate preparation step), and A carbon layer containing a carbonaceous material and a matrix resin made of a thermoplastic resin or a thermosetting resin is formed on at least one side (carbon layer forming step).

In the base material preparation step, a plate-shaped material made of a stainless steel plate having a predetermined chemical composition is prepared and then subjected to surface treatment.
First, steel having a predetermined chemical composition is melted in a vacuum furnace, cast into an ingot, and then hot forged, hot rolled, annealed, and cold rolled to obtain a plate material. A well-known method can be used for the treatment conditions of each step.
Next, at least one surface of the plate-like material is subjected to surface treatment such as pickling with a surface treatment liquid. After that, it is washed with pure water or the like. By this surface treatment, a plate-like substrate having a predetermined Cu and C content in the surface layer is obtained. As the surface treatment liquid, _an aqueous solution of hydrofluoric acid having a concentration of 1 to 10% by mass, or _an HF A hydrofluoric acid/nitric acid mixed aqueous solution having a concentration of 2% by mass or more can be used. Prior to performing the surface treatment step, at least one surface of the plate material is brought into contact with an acid aqueous solution containing iron chloride having an acid concentration of 25% by mass or more and an iron chloride concentration of 20% by mass or more as a pretreatment liquid. A pretreatment step may be performed.

The concentration of the hydrofluoric acid aqueous solution used as the surface treatment liquid is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 8% by mass or less. If the hydrofluoric acid concentration of the hydrofluoric acid aqueous solution is lower than 1% by mass, there is a possibility that the concentration (content) of Cu and C concentrated in the base material surface layer cannot be within the predetermined range. On the other hand, if the concentration is higher than 10% by mass, the elution of the material stainless steel is large, and the thickness of the oxide film formed on the surface becomes thick, which may increase the contact resistance. When a mixed aqueous solution of hydrofluoric acid and nitric acid is used as the surface treatment liquid, the concentration ratio (HF/HNO ₃ ) of hydrofluoric acid (HF) and nitric acid (HNO ₃ ) is preferably 2. Above, more preferably 2.5 or more, and the HF concentration is preferably 2% by mass or more, more preferably 3% by mass or more. If the concentration ratio (HF/HNO ₃ ) of hydrofluoric acid (HF) and nitric acid (HNO ₃ ) is less than 2, the contact resistance may exceed 10 mΩ·cm ² . Even if it is less than mass %, the contact resistance may be greater than 10 mΩ·cm ² . Even when used as a mixed aqueous solution, the concentration of hydrofluoric acid is preferably 10% by mass or less, more preferably 8% by mass or less, as described above. By this surface treatment, it is possible not only to remove the oxide film on the surface of the plate material, but also to make the content of Cu and C in the surface layer portion of the plate material concentrated to a predetermined level. For that purpose, it is necessary to appropriately set the surface treatment time. For example, when using a hydrofluoric acid aqueous solution (concentration 3 to 8% by mass) as the surface treatment liquid, the plate material is brought into contact with the surface treatment liquid at a treatment temperature of 40° C. or higher and 60° C. or lower for about 10 to 150 seconds. Let it be. After that, it is washed with pure water or the like.

In the pretreatment step that may be performed prior to the surface treatment, the plate-like material is immersed in a pretreatment liquid and then washed with pure water or the like. As the pretreatment liquid, an iron chloride-containing acid aqueous solution obtained by dissolving iron chloride such as FeCl ₃ in a non-oxidizing acid aqueous solution such as hydrochloric acid or hydrofluoric acid is used. Regarding the iron chloride-containing acid aqueous solution, the acid concentration is preferably 25% by mass or more, more preferably 30% by mass or more and 40% by mass or less, although it varies depending on the type of acid and the type of iron chloride used. The iron concentration is usually preferably 20% by mass or more, more preferably 20% by mass or more and 30% by mass or less. As for the pretreatment conditions for immersing the plate-shaped material in the ferric chloride-containing acid aqueous solution, the temperature is usually 30° C. or higher and 60° C. or lower and the treatment time is 30 seconds or longer and 3 minutes or shorter. By this pretreatment, pitting corrosion can be formed in advance in the relatively thick oxide film formed on the surface of the stainless steel in the annealing process, or the oxide film can be thinned. It becomes easy to control the structure of the oxide film.

A carbon layer forming step is performed on the plate-shaped base material obtained by the surface treatment. In the carbon layer forming step, a carbon layer containing a carbonaceous material and a matrix resin is formed on the surface of the plate-like substrate. A method for forming the carbon layer is not particularly limited. For example, a method of filling the surface of a plate-shaped substrate with a mixture containing a carbonaceous material (such as carbonaceous powder) and a matrix resin (such as resin powder) and hot-pressing it, or a method of adding resin powder and carbonaceous powder in a solvent. For example, the dispersed slurry is applied to the surface of stainless steel using a doctor blade or the like, dried, and then hot-pressed. Preferably, a powder mixture containing carbonaceous powder and resin powder is warm-pressed (hot-pressed) to form a sheet-like carbon layer in advance, and the resulting carbon layer is again hot-pressed on the surface of the plate-like substrate. A hot press method of pressing and laminating is preferably used. By forming a carbon layer by this hot pressing method and laminating the carbon layer, there is an advantage that the carbon layer can be continuously formed on the surface of the base material.

Further, in the present embodiment, prior to the carbon layer forming step, the adhesive composition is applied to the surface of the plate-like substrate to form an adhesive layer on the surface of the plate-like substrate. steps may be performed. In the carbon layer forming step, the carbon layer is formed via this adhesive layer. By performing the adhesive layer forming step prior to the carbon layer forming step, the adhesion between the plate-like substrate and the carbon layer is improved, and the stainless steel surface of the plate-like substrate is coated with the adhesive layer. Therefore, for example, when used as a polymer electrolyte fuel cell, there is an advantage that durability against corrosive environments is improved.

The stainless steel plate carbon composite material of the present embodiment obtained by the method of the present embodiment preferably has a contact resistance of 10 mΩ·cm ² or less, more preferably 5 mΩ·cm ² or less, and still more preferably 3 mΩ·cm ^{2 .} It is preferable that the contact resistance is not substantially changed even under the environment corresponding to the usage environment of the fuel cell.
The stainless steel plate carbon composite material of this embodiment not only excels in softness, flexibility, compressive strength, moldability, airtightness, etc., but also has excellent conductivity (low contact resistance) and corrosion resistance. Furthermore, it is also excellent in base material workability (adhesion between the base material and the carbon layer). The stainless steel plate carbon composite material of the present embodiment is used as separators for fuel cells such as polymer electrolyte fuel cells, current collector plates for redox flow secondary batteries, and gaskets and packings for petroleum refining and petrochemical plants. It is preferably used in When used as a separator for a polymer electrolyte fuel cell, for example, as shown in FIG. The structure 10 sandwiched by the fuel cell separators 5 via the gasket 9 is used as a unit cell, and several tens to several hundreds of these can be stacked to form a stack.

The stainless steel plate carbon composite material of this embodiment can also be used as a separator for an electrochemical hydrogen compressor. The electrochemical hydrogen compressor and its mechanism are not particularly limited, but known configurations and methods, for example, JP 2018-189300, JP 2018-95953, JP 2018-165385 etc., can be employed. An example (schematic diagram) of the configuration of an electrochemical hydrogen compressor is shown in FIG. For example, an anode provided with a catalyst layer is provided on one side of the proton-conducting electrolyte membrane 31, and a cathode provided with a catalyst layer is provided on the other side (anode and cathode are not distinguished). Both are denoted by reference numeral 32), these are made into an electrolyte-electrode assembly (MEA), and the MEA is sandwiched between separators 33 that may have gas diffusion channels. A feeder plate 34 is provided on the non-contact side, and the feeder plate 34 is sandwiched between separators. In such a configuration, when a hydrogen-containing gas is supplied to the anode while applying a potential difference between the anode and the cathode by voltage application means (not shown), hydrogen is separated into protons (H ⁺ ) and electrons in the catalyst layer of the anode. , electrons move from the anode to the cathode through the voltage applying means, the feeder plate and the separator. Protons move from the anode through the electrolyte membrane to the lower potential cathode. At that time, protons and electrons combine in the catalytic layer of the cathode to produce H ₂ . Then, by continuing the supply of the hydrogen-containing gas to the anode and the application of the above voltage, the production of H ₂ at the cathode continues and high pressure (=compressed) hydrogen gas is obtained at the cathode.
The stainless steel plate carbon composite material of the present embodiment has excellent conductivity (low contact resistance), so it contributes to the efficiency of the hydrogen generation reaction, etc., and has excellent corrosion resistance, so it can be used in a corrosion-resistant environment (wet, low pH). Furthermore, since it has excellent base material workability (adhesion between the base material and the carbon layer), there is little risk of deterioration in corrosion resistance, etc., so it can be suitably used as a separator for an electrochemical hydrogen compressor. .

Hereinafter, based on examples and comparative examples, the stainless steel plate (plate-shaped base material made of stainless steel) and stainless steel plate carbon composite material of the present embodiment, their manufacturing methods, and performance evaluations will be specifically described. .

1. Preparation of stainless steel plate (plate-shaped base material made of stainless steel) [preparation process of plate-shaped material made of stainless steel]
First, a plate-shaped material made of stainless steel was prepared as follows. That is, 150 kg of stainless steel having a chemical composition (unit: % by mass, the balance being Fe and impurities) as shown in Table 1 below was melted in a high-frequency induction heating type vacuum melting furnace to form an ingot. The resulting 150 kg ingot was hot forged at 1220°C, cut, hot rolled at 1220°C, annealed at 1180°C, cold rolled at 1080°C and annealed at 1080°C. °C to obtain a 50 μm thick stainless steel foil. These were plate-shaped materials a to n.

[Surface treatment process of plate material]
The obtained plate-shaped materials a to n were subjected to surface treatment to obtain respective stainless steel plates (plate-shaped substrates made of stainless steel). In the surface treatment, a 4% by mass hydrofluoric acid aqueous solution was used as a surface treatment liquid, and each plate-shaped material was immersed in this surface treatment liquid at 50° C. and pickled. The pickling time was as shown in Table 2. After pickling, the surface was washed with ultrapure water. The obtained stainless steel plates (stainless steel plate-shaped substrates) are referred to as plate-shaped substrates according to Examples 1 to 14 and Comparative Examples 1 to 10, respectively. It was used for quantity measurement (Test Example 7).

<Example 1>
2. Step of Laminating Carbon Layer Using the plate-shaped base material according to Example 1 obtained above, after forming an adhesive layer on the surface thereof, a carbon layer was further laminated.
[Adhesive Layer Forming Step]
A modified polyolefin resin adhesive (manufactured by Mitsui Chemicals, Inc., Unistol) was used as the adhesive composition for forming the adhesive layer. Then, this modified polyolefin resin adhesive was applied to the surface of the plate-shaped base material obtained above using a desktop coater so that the coating thickness was 10 μm, and dried at room temperature for 10 minutes to form an adhesive layer. , obtained as a plate-like substrate with an adhesive layer in Example 1.

[Formation of carbon layer]
Spherical graphite powder (manufactured by Ito Graphite Co., Ltd., trade name: SG-BH, average particle size: 20 μm) and expanded graphite powder (manufactured by Ito Graphite Co., Ltd., trade name: EC100, average particle size: 160 μm) were used as the carbonaceous material. used. Polypropylene resin (PP) powder (manufactured by Sumitomo Seika Chemicals Co., Ltd., trade name: Flowblen HP-8522) was used as the matrix resin. Then, 60% by volume of spherical graphite powder, 10% by volume of expanded graphite powder, and 30% by volume of polypropylene resin powder were mixed to obtain a powder mixture. 0.4 g of this powder mixture was applied to a press machine (desktop hot press MP-manufactured by Toyo Seiki Seisakusho Co., Ltd.) as shown in FIG. SCL) was evenly placed in a female mold with a volume of 50 × 50 × 20 mm, and a carbon layer 3 (thickness: 0 .1 mm). Next, as shown in FIGS. 2 and 3, the obtained carbon layer 3 and the adhesive layer-attached stainless steel plate-like substrate 4 prepared above are superimposed, heated at 180° C. (symbol T) and A pressure of 5 MPa (symbol P) was applied (main pressing, molding time: 10 minutes) to form a carbon layer 3 on one side of the plate-like base material 4 made of stainless steel. The composite material in which a carbon layer was formed on one side of the substrate (hereinafter referred to as a "single-sided composite material") was subjected to conductivity (contact resistance) evaluation (2) (Test Example 6) described later. An adhesive layer and a carbon layer are formed in the same manner on the other substrate surface, thereby forming carbon layers 3 on both surfaces of the plate-shaped substrate 4 made of stainless steel, according to Example 1. It was obtained as a stainless steel plate carbon composite material 1 (hereinafter referred to as a "double-sided composite material").

The stainless steel plate carbon composite material (double-sided composite material; Test Examples 1 to 5), single-sided composite material (Test Example 6), and plate-like substrate (Test Example 7) according to Example 1 obtained above are described below. As such, a corresponding evaluation was made for each.

[Test Example 1: Measurement of Cu content and C content of substrate surface layer (double-sided composite material)]
A test piece of 2 cm×2 cm was cut out from the stainless steel plate carbon composite material (double-sided composite material) according to Example 1. Next, as shown in FIG. 1, the carbon layer on one side of the test piece was completely removed by polishing with a rotary polishing machine to expose the substrate surface. After that, using SAICAS (Surface And Interfacial Cutting Analysis System) manufactured by Daipla Wintes, the exposed surface of the substrate was cut until the thickness of the substrate reached 5 μm.
Next, by glow discharge optical emission spectroscopy (GDS), elemental analysis was performed in the thickness direction from the cut surface side (that is, the direction from the cut surface side to the opposite substrate surface layer side). For GDS, GD-Profiler (Marcus-type high-frequency glow discharge emission spectrometer) manufactured by Horiba, Ltd. was used. The anode diameter (analysis area) was 4 mm in diameter. The RF output was 35 W, the sputtering gas type was Ar, and the pressure was 600 Pa. The measurement mode was a pulse sputtering mode, the sputtering interval was 300 sec, and the measurement interval was 0.04 sec.
From the results of elemental analysis thus obtained, the contents (% by mass) of Cu and C in the surface layer of the base material were obtained as integrated values in the following measurement ranges. Although the observation range was sufficiently set at about 200 nm, the measurement range (D1-D2) for Cu was about 10 nm, and the measurement range (D2-D3) for C was about 50 nm.
Cu: The position P in the substrate thickness direction where the measured peak intensity of Cu is maximum is specified, and the peak intensity of 1/50 of the peak intensity (maximum peak intensity) at this position P is measured. The position on the center side of the thickness direction) is D1, the position where the same peak intensity as this position D1 is measured on the substrate surface side (measurement object surface side) is D2, and the thickness range from these positions D1 to D2.
C: Starting from the position P where the Cu takes the maximum peak value, the peak intensity of C on the cutting surface side (the center side in the thickness direction of the base material) from this position P is 1/50 of the peak intensity of C at the position P. The thickness range from position D3 to D2 is defined as D3.
The results obtained are shown in Table 2 below.

[Test Example 2: Evaluation of corrosion resistance]
The test piece was immersed in a simulated fuel cell environment, and the corrosion resistance was evaluated based on the presence or absence of precipitates in the solution. Specifically, a test piece of 20 mm×20 mm was cut out from the obtained stainless steel plate carbon composite material (double-sided composite material) according to Example 1. This test piece was immersed in a sulfuric acid solution (pH 3) at 80°C containing 30 ppm of chloride ions (Cl ^- ) for 240 hours.
The results obtained are shown in Table 2 below.
◎: No precipitate △: No precipitate, but discoloration is observed in the solution ×: Precipitate

[Test Example 3: Evaluation of conductivity (contact resistance) (1) (double-sided composite material)]
The contact resistance with carbon paper was measured. FIG. 4 is a diagram showing the configuration of an apparatus for measuring the contact resistance of a test piece, and the contact resistance was measured using this apparatus.
First, a test piece 14 of 15 mm×15 mm was cut out from the carbon composite material (double-sided composite material) of the stainless steel plate according to Example 1 above. This test piece was sandwiched between a pair of carbon papers 15 [TGP-H-90 manufactured by Toray Industries, Inc.] used as a gas diffusion layer for fuel cells, and sandwiched between a pair of gold-plated platinum electrodes 16. is. The area of each carbon paper 15 was 1 cm ² . Next, a load of 10 kgf/cm ² (9.81×10 ⁵ Pa) was applied between the pair of platinum electrodes 16 . In FIG. 4, the directions of the loads are indicated by white arrows. In this state, a constant current was passed between the pair of platinum electrodes 16, and the voltage drop between the carbon paper 15 and the test piece 14 was measured. A resistance value was obtained based on this result. Since the obtained resistance value is the sum of the contact resistances on both sides of the test piece 14, it is divided by 2 to obtain the contact resistance value per side of the test piece 14, which is evaluated according to the following criteria.
The results obtained are shown in Table 2 below.
◎: Less than 5 mΩ・cm ² ○: 5 mΩ・cm ² or more and less than 10 mΩ・cm ² ×: 10 mΩ・cm ² or more

[Test Example 4: Evaluation of Adhesion between Substrate and Carbon Layer]
A test piece of 50 mm×50 mm was cut from the carbon composite material (both-sided composite material) of the stainless steel plate according to Example 1 within 24 hours from its production. The adhesion strength of this test piece was evaluated using the cross-cut method. In the test piece, 11 parallel cuts were made at 2 mm intervals from the coated surface side of the carbon layer to reach the stainless steel plate as the core material using a cutter knife. Then, 11 more cuts were made perpendicular to it to form 100 grids. A tape peeling test was performed on the grid points. Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. was used as the tape. Adhesion was evaluated based on the degree of peeling of the carbon layer when the tape attached to the evaluation surface was peeled off.
The results obtained are shown in Table 2 below.
◎: No peeling is observed in any lattice ○: Carbon layer is peeled at 0 or more and less than 5% ×: Carbon layer is peeled at 5% or more

[Test Example 5: Evaluation of deterioration of matrix resin in carbon layer (evaluation of copper damage)]
The stainless steel plate carbon composite material (double-sided composite material) according to Example 1 was stored under normal temperature and normal pressure for 30 days. A 50 mm x 50 mm specimen was then cut from the double-sided composite. The adhesion strength of this test piece was evaluated using the cross-cut method. In the test piece, 11 parallel cuts were made at 2 mm intervals from the coated surface side of the carbon layer to reach the stainless steel plate as the core material using a cutter knife. Further 11 cuts were made perpendicular to it to form 100 grids. A tape peeling test was performed on the grid points. Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. was used as the tape. Adhesion was evaluated based on the degree of peeling of the carbon layer when the tape attached to the evaluation surface was peeled off.
The results obtained are shown in Table 2 below.
◎: No peeling is observed in any lattice ○: Carbon layer is peeled at 0 or more and less than 5% ×: Carbon layer is peeled at 5% or more

[Test Example 6: Evaluation of conductivity (contact resistance) (2) (single-sided composite material)]
Contact resistance with stainless steel was measured. The apparatus shown in FIG. 7 was used for the measurement of this contact resistance.
A test piece 20 of 15 mm×15 mm was cut out from the single-sided composite material according to Example 1 above. A stainless steel material (SUS316L) 21 used as one of the feed plates in an electrochemical hydrogen compressor is stacked on the side of the test piece 20 on which the carbon layer is not laminated, and these test pieces 20 and the stainless steel material 21 are laminated. The body was sandwiched between a pair of gold-plated platinum electrodes 23 . The stainless steel material 21 had an area of 1 cm ² and a thickness of 5 mm. Next, a load of 10 kgf/cm ² (9.81×10 ⁵ Pa) was applied between the pair of platinum electrodes 23 . In FIG. 7, the directions of the loads are indicated by white arrows. In this state, a constant current was passed between the pair of platinum electrodes 23, and the electrical resistance generated at this time was measured. The electrical resistance values obtained at that time are the contact resistance between the lower platinum electrode 23 and the test piece 20, the contact resistance between the test piece 20 and the stainless steel material 21, and the contact resistance between the stainless steel material 21 and the upper platinum electrode 23. is the sum of all the values (R1). Therefore, using the same device, the value (R2) obtained by dividing the electrical resistance when only the stainless steel material 21 is sandwiched between the platinum electrodes 23 by 2 is obtained. The value (R3) obtained by dividing the electrical resistance when sandwiched by 23 by 2 is obtained, and the sum of these values (R2 + R3) is subtracted from the total electrical resistance value (R1) to obtain the relationship between the stainless steel material 21 and the test piece 20. contact resistance. This contact resistance value was evaluated according to the following criteria.
The results obtained are shown in Table 2 below.
◎: Less than 10 mΩ・cm ² ○: 10 mΩ・cm ² or more and less than 20 mΩ・cm ² ×: 20 mΩ・cm ² or more

[Test Example 7: Measurement of Cu content and C content of base material surface layer (plate-like base material)]
A test piece of 2 cm×2 cm was cut out from the plate-like substrate according to Example 1.
Next, by glow discharge optical emission spectrometry (GDS), elemental analysis was performed in the thickness direction from the substrate surface (outermost surface) (that is, the direction from the substrate surface to the center in the thickness direction of the substrate). . For GDS, GD-Profiler (Marcus-type high-frequency glow discharge emission spectrometer) manufactured by Horiba, Ltd. was used. The anode diameter (analysis area) was 4 mm in diameter. The RF output was 35 W, the sputtering gas type was Ar, and the pressure was 600 Pa. The measurement mode was a pulse sputtering mode, the sputtering interval was 300 sec, and the measurement interval was 0.04 sec.
From the results of elemental analysis thus obtained, the contents (% by mass) of Cu and C in the surface layer of the plate-like substrate were obtained as integrated values in the following measurement ranges. Although the observation range was sufficiently set to about 200 nm, the measurement range for Cu (D1' to D2') was about 10 nm, and the measurement range for C (D2' to D3') was about 50 nm.
Cu: Identify the position P 'in the substrate thickness direction where the measured peak intensity of Cu is maximum, and measure the peak intensity of 1/50 of the peak intensity (maximum peak intensity) at this position P 'In the substrate thickness direction The thickness range from the outermost surface of the plate-like substrate (this is position D2') to position D1'.
C: Starting from the position P ' in the substrate thickness direction where the Cu takes the maximum peak value, the peak intensity of C on the center side of the substrate thickness direction from this position P ' is the peak intensity of C at the position P ' The thickness range from the outermost surface of the plate-like substrate (position D2') to position D3', where the position of 1/50 is D3'.
The results obtained are shown in Table 2 below.
The positions P, D1, and D3 in the substrate thickness direction in the measurement of the stainless steel plate carbon composite material were the same as the positions P′, D1′, and D3′ in the substrate thickness direction in the measurement of the plate-like substrate, respectively. .

<Examples 2-3>
Example 2 or 3 obtained by using the same plate material a as in Example 1, but changing the surface treatment (acid cleaning) time to 30 seconds (Example 2) or 60 seconds (Example 3). An adhesive layer and a carbon layer were laminated in the same manner as in Example 1, except that each of the plate-shaped substrates was used, and the stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Example 2 or Example 3 Composite material) was obtained, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Examples 4-5>
Example 4 or 5 obtained by changing the plate material from Example 1 to b (Example 4) or c (Example 5) and changing the surface treatment (acid cleaning) time to 60 seconds The stainless steel plate carbon composite material (single-sided composite material and A double-sided composite material) was obtained, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Example 6>
Examples except that the plate-shaped substrate according to Example 6 obtained by changing the plate-shaped material from Example 1 to c and changing the surface treatment (acid cleaning) time to 120 seconds was used. An adhesive layer and a carbon layer were laminated in the same manner as in 1 to obtain a stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Example 6, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Example 7>
Examples except that the plate-shaped substrate according to Example 7 obtained by changing the plate-shaped material from Example 1 to d and changing the surface treatment (acid cleaning) time to 60 seconds was used. An adhesive layer and a carbon layer were laminated in the same manner as in 1 to obtain a stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Example 7, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Comparative Examples 1 and 2>
Comparative Example 1 or 2 obtained by changing the plate material from Example 1 to e (Comparative Example 1) or f (Comparative Example 2) and changing the surface treatment (acid cleaning) time to 60 seconds An adhesive layer and a carbon layer are laminated in the same manner as in Example 1, except that the plate-shaped substrates according to are used respectively, and the stainless steel plate carbon composite material according to Comparative Example 1 or Comparative Example 2 (single-sided composite material and A double-sided composite material) was obtained, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Comparative Examples 3-4>
Plate-shaped substrates according to Comparative Examples 3 and 4 obtained by changing the surface treatment (acid cleaning) time from Example 1 to 3 seconds (Comparative Example 3) or 600 seconds (Comparative Example 4) were used, respectively. Except that, an adhesive layer and a carbon layer are laminated in the same manner as in Example 1 to obtain a stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Comparative Example 3 or Comparative Example 4, and the same Various evaluations were performed on
The results obtained are shown in Table 2 below.

<Comparative Example 5>
A plate-shaped substrate according to Comparative Example 5 obtained by changing the surface treatment (acid cleaning) time from Example 1 to 60 seconds was used, but the adhesive layer and the carbon layer were not laminated, and the plate-shaped substrate was used. Only the contact resistance (Test Example 3) and corrosion resistance (Test Example 2) were evaluated. The amount of Cu and the amount of C in the substrate surface layer were measured by the method according to Test Example 7 above.
The results obtained are shown in Table 2 below.

<Examples 8-9>
Example 8 or 9 obtained by changing the plate material from Example 1 to g (Example 8) or h (Example 9) and changing the surface treatment (acid cleaning) time to 60 seconds An adhesive layer and a carbon layer are laminated in the same manner as in Example 1, except that the plate-shaped substrates according to are used respectively, and the stainless steel plate carbon composite material according to Example 8 or Example 9 (single-sided composite material and A double-sided composite material) was obtained, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Comparative Example 6>
Examples except that the plate-shaped substrate according to Comparative Example 6 obtained by changing the plate-shaped material from Example 1 to i and changing the surface treatment (acid cleaning) time to 60 seconds was used. An adhesive layer and a carbon layer were laminated in the same manner as in 1 to obtain a stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Comparative Example 6, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Example 10>
Examples except that the plate-shaped substrate according to Example 10 obtained by changing the plate-shaped material from Example 1 to j and changing the surface treatment (acid cleaning) time to 60 seconds was used. An adhesive layer and a carbon layer were laminated in the same manner as in 1 to obtain a stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Example 10, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Comparative Examples 7-8>
Comparative Example 7 or 8 obtained by changing the plate material from Example 1 to k (Comparative Example 7) or l (Comparative Example 8) and changing the surface treatment (acid cleaning) time to 60 seconds An adhesive layer and a carbon layer are laminated in the same manner as in Example 1, except that the plate-shaped substrates according to are used respectively, and the stainless steel plate carbon composite material (single-sided composite material and A double-sided composite material) was obtained, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Examples 11-12>
Example 11 or 12 obtained by changing the plate material from Example 1 to m (Example 11) or n (Example 12) and changing the surface treatment (acid cleaning) time to 60 seconds The stainless steel plate carbon composite material (single-sided composite material and A double-sided composite material) was obtained, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Example 13>
Examples except that the plate-shaped substrate according to Example 13 obtained by changing the plate-shaped material from Example 1 to c and changing the surface treatment (acid cleaning) time to 20 seconds was used. An adhesive layer and a carbon layer were laminated in the same manner as in 1 to obtain a stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Example 13, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

<Comparative Examples 9 to 10>
Plate-shaped substrates according to Comparative Examples 9 and 10 obtained by changing the surface treatment (acid cleaning) time from Example 1 to 1200 seconds (Comparative Example 9) or 1000 seconds (Comparative Example 10) were used, respectively. Except that, an adhesive layer and a carbon layer are laminated in the same manner as in Example 1 to obtain a stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Comparative Example 9 or 10, and various made an evaluation.
The results obtained are shown in Table 2 below.

<Example 14>
Using the plate-like substrate according to Example 14 obtained by changing the surface treatment (acid cleaning) time from Example 1 to 60 seconds, and using isopropyl alcohol as an adhesive layer so that the amount is 5 wt% A phenol resin adhesive (Lignite Co., Ltd. phenol resin, trade name: AH-1148) in which phenol resin (PF) is dissolved is used, and a phenol resin (Lignite Co., Ltd. product) is used as the matrix resin for obtaining the carbon layer. Name: AH-1148), and furthermore, the pre-press temperature when laminating the carbon layer was 80 ° C. and the main press temperature was 150 ° C. The same adhesive layer and carbon layer as in Example 1. was laminated to obtain a stainless steel plate carbon composite material (single-sided composite material and double-sided composite material) according to Example 14, and various evaluations were performed in the same manner.
The results obtained are shown in Table 2 below.

As can be seen from Tables 1 and 2 above, stainless steel sheet materials a to d, g, h, j, m or n having predetermined element (especially C, Cr and Cu) contents are used. Also, according to Examples 1 to 14 using a plate-shaped substrate in which the Cu and C contents concentrated in the surface layer of the substrate are within a specific range by adjusting the time of surface treatment (pickling treatment) In Test Examples 1 to 5, the stainless steel plate carbon composite material (double-sided composite material) was good in all of contact resistance (electrical conductivity), corrosion resistance, adhesion between the base material and the carbon layer, and suppression of copper damage.

The stainless steel plate carbon composite material according to Comparative Example 1, which uses a plate-shaped substrate obtained from a plate-shaped material e having a low Cr content, has Cu and C content in the substrate surface layer by adjusting the surface treatment (pickling treatment) time. Although the amount was within the specified range, the corrosion resistance was insufficient. It is presumed that this is because the passivation film was not sufficiently formed. On the other hand, the stainless steel plate carbon composite materials according to Comparative Examples 2 and 6, which used plate-shaped substrates obtained from plate-shaped materials f or i having a high Cr content, had high contact resistance and poor electrical conductivity. It is presumed that this is because the passivation film was excessively formed.

In the stainless steel plate carbon composite material according to Comparative Example 7 using the plate-shaped base material obtained from the plate-shaped material k having a high Cu content, even if the surface treatment (pickling treatment) is the same as that of the example, the base material The Cu content of the surface layer was too high. Further, the stainless steel plate carbon composite material according to Comparative Example 8 using the plate-shaped base material obtained from the plate-shaped material 1 with a low Cu content was subjected to the same surface treatment (pickling treatment) as in the example, The Cu content of the substrate surface layer was too low. In Comparative Example 7, deterioration of the carbon layer due to copper damage was observed. In Comparative Example 8, the contact resistance was high.

Even in the case of using a plate-shaped material a having a predetermined element (especially C, Cr and Cu) content, in Comparative Example 3 using a plate-shaped substrate with a short surface treatment (pickling treatment) time The stainless steel plate carbon composite material had a low Cu content in the base material surface layer. Therefore, the contact resistance was high.
On the contrary, the stainless steel plate carbon composite materials according to Comparative Examples 4 and 10, in which the plate-shaped material a was used and the plate-shaped base material having a long surface treatment (pickling treatment) time was used, contained Cu in the surface layer of the base material. quantity was high. Therefore, deterioration of the carbon layer due to copper damage was observed. In addition, in the stainless steel plate carbon composite material according to Comparative Example 9 in which the plate-shaped material a was used and the plate-shaped substrate having a longer surface treatment (pickling treatment) time was used, the Cu content was high in the substrate surface layer. , and the C content was low. Therefore, deterioration of the carbon layer due to copper damage was observed, and the adhesion between the substrate and the carbon layer was insufficient.

Using a plate-shaped material a having a predetermined element content, a plate-shaped substrate having a Cu and C content in the surface layer of the substrate within a specific range was obtained by performing the same surface treatment (pickling treatment) as in the example. Even when it was used, corrosion resistance was not sufficient in Comparative Example 5 in which no carbon layer was used.

According to the results of Test Example 6 [evaluation of contact resistance (2)] using a single-sided composite material, both tend to be the same as the results of Test Example 3 [evaluation of contact resistance (1)] using a double-sided composite material. was gotten. That is, in the examples satisfying the present embodiment, excellent results were obtained in terms of conductivity (low contact resistance) with the stainless steel material (reference numeral 21), and the contact resistance with the power supply plate used in the electrochemical hydrogen compressor can be reduced. Considering this result and the results of the double-sided composite material described above, it was found that the stainless steel plate carbon composite material of the present embodiment is also suitable as a separator for an electrochemical hydrogen compressor.

From the results of Test Example 7, the contents of Cu and C on the surface of each plate-shaped base material before forming the carbon layer were, in all examples, The result was less than the content of Cu and C. This is presumed to be due to the difference in the measurement method (difference in the "measurement range" due to the difference in the measurement position on the substrate surface) as described above.

DESCRIPTION OF SYMBOLS 1... Stainless steel plate carbon composite material, 2... Adhesive layer, 3... Carbon layer, 4... Stainless steel plate-shaped base material, 5... Separator for fuel cell, 6... Solid polymer electrolyte membrane, 7... Anode (fuel electrode ), 8... Cathode (oxidant electrode), 9... Gasket, 10... Unit cell, 11... Groove for gas supply and discharge, 12... Opening, 13... Fixing hole, 14... Test piece, 15... Carbon paper, 16... Platinum electrode 17 Solid polymer fuel cell 20 Test piece 21 Stainless steel material 23 Platinum electrode 31 Proton conductive electrolyte membrane 32 Anode or cathode 33 Separator 34 Power supply plate DESCRIPTION OF SYMBOLS 100... Press apparatus, 101... Male type, 102... Female type, 103... Mold, 104... Machine frame, 105... Hydraulic cylinder

Claims (8)

A stainless steel plate carbon composite material in which a carbon layer containing a carbonaceous material and a matrix resin made of a thermoplastic resin or a thermosetting resin is laminated on at least one side of a plate-shaped base material made of stainless steel,
The base material contains at least 0.001 to 0.2% by mass of carbon (C), 9.0% to 16.0% by mass of chromium (Cr), and 0.005 to 1% of copper (Cu). .0% by mass, and in quantitative elemental analysis in the thickness direction of the substrate surface layer by glow discharge emission spectrometry, the Cu content in the measurement range defined in (i) below is 0.010 to 0.30 A stainless steel plate carbon composite material having a C content of 2 to 15% by mass, and a C content in the measurement range defined in (ii) below.
(i) The substrate center side where the peak intensity of 1/50 of the peak intensity (maximum peak intensity) at this position P is measured across the position P where the peak intensity of Cu measured on the substrate surface layer is maximum and a position D2 where the same peak intensity as this position D1 is measured on the substrate surface side.
(ii) A range connecting the position D3 on the substrate center side where the intensity of 1/50 of the peak intensity of C at the position P is measured, and the position D2 on the substrate surface side, with the position P interposed therebetween. The stainless steel plate carbon composite material according to claim 1, wherein the base material has the following chemical composition.
C: 0.001 to 0.2% by mass,
Si: 0.01 to 2.0% by mass,
Mn: 0.01 to 2.5% by mass,
Al: 0.001 to 0.5% by mass,
Cr: 9.0% by mass or more and less than 16.0% by mass,
Cu: 0.005 to 1.0% by mass,
P: 0.1% by mass or less,
S: 0.01% by mass or less,
Ni: 0 to 0.3% by mass,
Ti: 0 to 2.0% by mass,
Mo: 0 to 3.0% by mass,
V: 0 to 1.0% by mass,
Nb: 0 to 1.0% by mass,
W: 0 to 1.0% by mass,
Ta: 0 to 1.0% by mass,
Sb: 0 to 1.0% by mass,
Pb: 0-1.0% by mass, and balance: Fe and impurities. A fuel cell separator using the stainless steel plate carbon composite material according to claim 1 or 2. A fuel cell comprising the fuel cell separator according to claim 3 . A fuel cell stack comprising the fuel cell according to claim 4 . A separator for an electrochemical hydrogen compressor using the stainless steel plate carbon composite material according to claim 1 or 2. An electrochemical hydrogen compressor comprising the separator for an electrochemical hydrogen compressor according to claim 6. A stainless steel plate,
Contains at least 0.001 to 0.2 mass% of carbon (C), 9.0 mass% to less than 16.0 mass% of chromium (Cr), and 0.005 to 1.0 mass% of copper (Cu) In addition, in quantitative elemental analysis in the thickness direction of the surface layer by glow discharge emission spectrometry, the Cu content in the measurement range defined in (i') below is 0.008 to 0.28% by mass, and the following A stainless steel plate having a C content of 1.8 to 13.5% by mass in the measurement range defined in (ii').
(i') The peak intensity of 1/50 of the peak intensity (maximum peak intensity) at this position P' is measured across the position P' where the peak intensity of Cu measured on the surface layer of the steel sheet is maximum. A range connecting a position D1′ on the center side of the steel plate and the surface of the steel plate.
(ii') A range connecting a position D3' on the center side of the steel sheet, where the strength of 1/50 of the peak strength of C at the position P' is measured, and the surface of the steel sheet, sandwiching the position P'.

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