Separator manufacturing method, fuel cell manufacturing method, and separator manufacturing apparatus

Abstract

To manufacture products that hardly cause damage due to vibration or shock, that can be miniaturized, and that have a sufficient high degree of freedom in design.SOLUTION: A separator for a fuel cell, which includes a groove that allows gas for power generation to pass therethrough and a carburized part formed on both sides of a laminate 55a, is manufactured by performing in the following order: first processing of housing a laminate 55b in a processing tank, the laminate being formed by layering a carbon sheet Sc on both sides of the laminate 55a that is formed by layering plates 71-73, 81, 82 including a plate 71 provided with a slit and a plate 72 provided with a closing part, and increasing the degree of vacuum in the processing tank; second processing of increasing the temperature of the laminate 55b to a first temperature to reduce and remove a passive film of each plate; third processing of increasing the temperature of the laminate 55b to a second temperature higher than the first temperature while the laminate 55b is pressurized, thereby subjecting each plate to diffusion bonding; and fourth processing of lowering the temperature of the laminate 55b and lowering the degree of vacuum in the processing tank.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a separator manufacturing method and separator manufacturing apparatus for manufacturing a separator for a fuel cell having grooves through which gas used for power generation can pass, and a fuel cell manufacturing method for manufacturing a fuel cell using a separator manufactured by such a separator manufacturing method. [Background technology]

[0002] A solid polymer electrolyte fuel cell is configured to include an electrolyte membrane, a pair of electrodes, and a pair of separators. In this case, it is known that a fuel cell with good power generation efficiency can be manufactured by adopting a carbon separator mainly made of carbon. A method for manufacturing this carbon separator is known in which a kneaded mixture of carbon and thermosetting resin is injected into a mold, the mixture is heated to a temperature at which the thermosetting resin melts, and then the mixture is compressed and heated to a temperature at which the thermosetting resin hardens to harden it. However, when manufacturing a separator using this manufacturing method, the molding material (kneaded material) injected into the mold contains a large amount of carbon compared to when manufacturing a general resin molded product, so the viscosity of the molding material is high and its fluidity is poor, and the molding material may solidify before filling every corner of the cavity in the mold. This may make it difficult to manufacture a separator with a desired shape.

[0003] On the other hand, the following patent document discloses a method and an apparatus for forming a carbon separator for a fuel cell, which is made to solve the above problems. In this method and apparatus, a carbon resin material is formed by applying a resin material for molding (thermosetting resin material) to the surface of a carbon powder made of a granular solid to form a coating layer, and a liquid (water, alcohol, Fluorinert, etc.) for improving the fluidity is mixed and kneaded to form a molding material (kneaded material) into a mold, and the liquid in the injected molding material (kneaded material) is discharged outside the mold through a small hole provided in the mold. As a result, the molding material has high fluidity at the time of injection into the mold, so that the molding material can be filled into every corner of the mold. This makes it possible to manufacture a carbon separator of a desired shape. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-207684 A (pages 4-9, figures 1-9) Summary of the Invention [Problem to be solved by the invention]

[0005] However, the carbon separators (hereinafter simply referred to as "separators") manufactured by the manufacturing methods and manufacturing apparatuses disclosed in the above patent documents have the following problems to be solved. Specifically, the separator molding apparatus and molding method disclosed in the above patent documents employ a configuration and method in which a carbon resin material (molding material) is injected into a mold and hardened. This makes it possible to reliably manufacture separators of the desired shape, compared to conventional molding apparatuses and molding methods.

[0006] However, although molded products manufactured by this type of molding method and molding apparatus can have a certain degree of hardness depending on the type of resin material used in the molding material, it is known that the molding material contains granular solids (carbon powder) and therefore has low toughness, making it prone to cracking when subjected to vibration or impact. For this reason, in fuel cell cells manufactured using separators molded by this molding apparatus and molding method, cracks may occur in the separator due to vibration or impact applied to the power generation device, and when cracks occur in the hydrogen cell, this may lead to hydrogen gas leakage, and when cracks occur in the air separator, the amount of oxygen to react with hydrogen gas may decrease, causing a decrease in power generation efficiency.

[0007] Furthermore, to prevent cracks caused by vibration or impact, the separator needs to be formed to a sufficient thickness to ensure the physical strength of the separator itself. This makes it difficult to miniaturize fuel cells manufactured using separators molded by this molding device and molding method. Furthermore, in the separator molding device and molding method disclosed in the above patent document, the shape of the molded product is limited to a "shape that can be removed from a mold (a shape that can be demolded)." This also creates the problem of low freedom in designing the shape of the separator.

[0008] The present invention has been made in consideration of the above-mentioned problems that need to be improved, and has as its main object to provide a separator manufacturing method, a fuel cell manufacturing method, and a separator manufacturing apparatus that are capable of manufacturing products that are less susceptible to damage caused by vibration or impact, can be made compact, and have a sufficiently high degree of design freedom. [Means for solving the problem]

[0009] In order to achieve the above object, the separator manufacturing method according to claim 1 is a separator manufacturing method for manufacturing a fuel cell separator provided with a groove portion for passing a power generation gas, the method including: a first stack of a plurality of plates including at least a first metal plate provided with a slit penetrating in a plate thickness direction and a second metal plate provided with a blocking portion for blocking one end of the slit in the plate thickness direction; placing a second stack of a carbon sheet on at least one surface in the plate thickness direction of the first stack in a treatment tank; and heating the second stack to a predetermined first temperature. a second process of increasing the temperature of the second stack to reduce and remove the passivation film of the multiple plates; a third process of increasing the temperature of the second stack to a predetermined second temperature higher than the first temperature while pressurizing the second stack with a predetermined pressure, thereby diffusion bonding the multiple plates; and a fourth process of decreasing the temperature of the second stack and decreasing the degree of vacuum in the treatment tank, in that order, to manufacture the fuel cell separator in which the groove portion is formed by the slit and the blocking portion and a carburized portion is formed on at least one of the surfaces of the first stack.

[0010] The separator manufacturing method of claim 2 is the separator manufacturing method of claim 1, in which when manufacturing the fuel cell separator using the second stack in which the carbon sheet is layered on the first stack in which the multiple plates are layered so that at least one of the surfaces is formed by the first metal plate, a fifth process is carried out to remove the carbon sheet that remains without being carburized on the first metal plate in the second stack after completing the fourth process, thereby exposing the groove portion.

[0011] The separator manufacturing method of claim 3 is the separator manufacturing method of claim 1, in which, when manufacturing the fuel cell separator using the second stack in which the carbon sheet is superimposed on the first stack in which the plurality of plate bodies are superimposed so that at least one surface is formed by a plate body other than the first metal plate, a fifth process is carried out to remove the carbon sheet that remains without being carburized on the plate bodies other than the first metal plate in the second stack that has completed the fourth process.

[0012] A separator manufacturing method according to a fourth aspect of the present invention is the separator manufacturing method according to the first aspect, wherein in the fourth treatment, nitrogen is caused to flow into the treatment tank to reduce the degree of vacuum in the treatment tank.

[0013] A separator manufacturing method according to a fifth aspect of the present invention is the separator manufacturing method according to the first aspect, wherein in the fourth treatment, gas in the treatment tank is blown toward the second laminate to lower the temperature of the second laminate.

[0014] The fuel cell manufacturing method described in claim 6 manufactures a fuel cell by sandwiching a fuel cell membrane electrode assembly between a plurality of fuel cell separators manufactured by the separator manufacturing method described in any one of claims 1 to 5, and integrating the fuel cell separators and the fuel cell membrane electrode assembly in a state where the fuel cell separators and the fuel cell membrane electrode assembly are integrated.

[0015] The separator manufacturing apparatus according to claim 7 is a separator manufacturing apparatus for manufacturing fuel cell separators provided with grooves for passing a power generation gas, and the separator manufacturing apparatus includes a treatment tank capable of accommodating a second stack having a carbon sheet laminated on at least one surface in the thickness direction of a first stack obtained by stacking in the thickness direction a plurality of plates including at least a first metal plate provided with a slit penetrating in the thickness direction and a second metal plate provided with a blocking portion that blocks one end of the slit in the thickness direction, a vacuum adjustment unit that adjusts the vacuum in the treatment tank, a temperature adjustment unit that adjusts the temperature of the second stack accommodated in the treatment tank, a pressurization unit that pressurizes the second stack accommodated in the treatment tank in the thickness direction, and a control unit that controls operations of the vacuum adjustment unit, the temperature adjustment unit and the pressurization unit, and the control unit controls the vacuum adjustment unit to pressurize the second stack a first process of increasing the degree of vacuum in the treatment tank in which the first stack is housed, a second process of controlling the temperature adjustment unit to increase the temperature of the second stack to a predetermined first temperature to reduce and remove the passivation film of the multiple plates, a third process of controlling the temperature adjustment unit to increase the temperature of the second stack to a predetermined second temperature that is higher than the first temperature while the second stack is pressed by the pressurizing unit with a predetermined pressure, to diffusion bond the multiple plates, and a fourth process of controlling the temperature adjustment unit to decrease the temperature of the second stack and to decrease the degree of vacuum in the treatment tank, in that order, thereby manufacturing the fuel cell separator in which the groove portion is formed by the slit and the blockage portion and in which a carburized portion is formed on at least one surface of the first stack. Effect of the Invention

[0016] In the separator manufacturing method according to claim 1, a first laminate is formed by stacking a plurality of plates in the thickness direction, the first laminate including at least a first metal plate having a slit penetrating the plate thickness direction and a second metal plate having a blocking portion for blocking one side of the slit in the plate thickness direction. The second laminate is formed by stacking a carbon sheet on at least one surface in the thickness direction of the first laminate in a treatment tank, and the degree of vacuum in the treatment tank is increased as a first treatment. The second laminate is formed by stacking a plurality of plates in the thickness direction, the first laminate including at least a first metal plate having a slit penetrating the plate thickness direction and a second metal plate having a blocking portion for blocking one side of the slit in the plate thickness direction. The second laminate is then placed in a treatment tank as a first treatment, and the second laminate is heated to a predetermined first temperature to reduce and remove the passivation film of the plurality of plates. By carrying out the second process, a third process in which the temperature of the second stack is increased to a predetermined second temperature higher than the first temperature while pressurizing the second stack with a predetermined pressure to diffusion bond multiple plates, and a fourth process in which the temperature of the second stack is decreased and the degree of vacuum in the treatment tank is decreased, in that order, a fuel cell separator is manufactured in which a groove portion for passing power generation gas is formed by the slits and the blockage portion, and a carburized portion is formed on at least one surface of the first stack.

[0017] In a fuel cell manufacturing method described in claim 6, a fuel cell is manufactured by integrating a fuel cell separator and a fuel cell membrane electrode assembly in a state where the fuel cell separator is sandwiched between a plurality of fuel cell separators manufactured by the separator manufacturing method. In a separator manufacturing apparatus described in claim 7, the apparatus includes a treatment tank capable of accommodating the second stack, a vacuum adjustment unit that adjusts the vacuum in the treatment tank, a temperature adjustment unit that adjusts the temperature of the second stack accommodated in the treatment tank, a pressurizing unit that pressurizes the second stack accommodated in the treatment tank in the plate thickness direction, and a control unit that controls the operation of the vacuum adjustment unit, the temperature adjustment unit, and the pressurizing unit, and the control unit performs the first process, the second process, the third process, and the fourth process in this order to manufacture a fuel cell separator.

[0018] Therefore, according to the separator manufacturing method of claim 1, the fuel cell manufacturing method of claim 5, and the separator manufacturing apparatus of claim 6, a fuel cell separator having sufficiently high hardness, rigidity, and toughness can be manufactured by using a metal plate as a material, compared with a carbon separator manufactured by a molding method using a mixture of a carbon resin material in which a thermosetting resin material is applied to the surface of carbon powder to form a coating layer, and a liquid such as water is mixed and kneaded. This makes it possible to provide a fuel cell separator and a fuel cell that are less likely to be damaged due to vibration or impact. In addition, since it is not necessary to make the thickness of each part excessively thick in order to ensure the physical strength of the fuel cell separator, the fuel cell separator and the fuel cell can be sufficiently miniaturized. In addition, since it is not necessary to design the shape taking into account mold release (removal from the mold after molding is completed), the degree of freedom in design is sufficiently high, and the separator can be manufactured in any shape according to the required power generation capacity and use. Furthermore, the presence of the carburized portion on the surface portion sufficiently reduces the electrical resistance of the portion in contact with the fuel cell membrane electrode assembly, current collector plate, etc., making it possible to provide a fuel cell separator with excellent electrical properties and a fuel cell with sufficiently high power generation efficiency. In addition, the carburized portion functions as a protective layer, making it possible to provide a product with excellent corrosion resistance.

[0019] In addition, in the separator manufacturing method described in claim 2, when manufacturing a fuel cell separator using a second stack in which a carbon sheet is layered on a first stack in which a plurality of plate bodies are layered so that at least one surface is formed by a first metal plate, a fifth process is performed to remove the carbon sheet remaining on the first metal plate in the second stack after the fourth process is completed, thereby exposing a groove portion. In addition, in the separator manufacturing method described in claim 3, when manufacturing a fuel cell separator using a second stack in which a carbon sheet is layered on a first stack in which a plurality of plate bodies are layered so that at least one surface is formed by a plate body other than the first metal plate among the plurality of plate bodies, a fifth process is performed to remove the carbon sheet remaining on the plate body other than the first metal plate in the second stack after the fourth process is completed.

[0020] Therefore, according to the separator manufacturing method according to claims 2 and 3, and the fuel cell manufacturing method using the separator manufactured according to the separator manufacturing method, the fifth process is performed, that is, on the premise that the carbon sheet remains after the completion of the fourth process, a series of processes from the first process to the fourth process can be performed on the second laminate in which a carbon sheet of sufficient thickness is laminated on the first laminate, so that the carburized part can be preferably formed over the entire area of ​​the carbon sheet laminate, avoiding the occurrence of a portion where the carburized part is not preferably formed due to the occurrence of a tear in the carbon sheet before the completion of the fourth process. In addition, since the surface flatness of the fuel cell separator can be sufficiently improved when the remaining carbon sheet is removed, the fuel cell separator can be preferably adhered to other laminates in a laminate (fuel cell) including the fuel cell separator. This makes it possible to preferably avoid a situation where a gas for generating electricity leaks.

[0021] In the separator manufacturing method according to claim 4, nitrogen is introduced into the treatment tank in the fourth treatment to reduce the degree of vacuum in the treatment tank. Therefore, the separator manufacturing method according to claim 3 and the fuel cell manufacturing method for manufacturing a fuel cell using a separator manufactured according to the separator manufacturing method can sufficiently reduce the amount of oxygen that comes into contact with the second laminate heated to a high temperature in the third treatment, unlike a manufacturing method in which air (atmosphere) is introduced into the treatment tank to reduce the degree of vacuum, and therefore it is possible to suitably prevent the surface of the second laminate from being oxidized and a passivation film from being formed. In addition, since nitrogen is relatively inexpensive, has low danger at high temperatures, and is harmless even if released into the atmosphere when the door of the treatment tank is opened after the treatment is completed, it is possible to prevent the manufacturing costs of fuel cell separators from rising, the occurrence of accidents during manufacturing, and the occurrence of environmental damage.

[0022] In the separator manufacturing method according to claim 5, the gas in the treatment tank is blown toward the second stack in the fourth treatment to lower the temperature of the second stack. Therefore, according to the separator manufacturing method according to claim 4 and the fuel cell manufacturing method for manufacturing a fuel cell using a separator manufactured according to the separator manufacturing method, the amount of temperature drop in each part of the second stack can be made uniform, and the thermal shrinkage state of each part can be made similar, so that unintended deformation or cracks in the fuel cell separator can be preferably avoided. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a configuration diagram showing the configuration of a separator manufacturing apparatus 1. [Diagram 2] 2 is a cross-sectional view of a fuel cell 50. FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 2 is a plan view of a carbon sheet Sc. [Figure 9] FIG. 4 is a cross-sectional view of laminates 55a and 55b. [Figure 10] 10 is an explanatory diagram for explaining the degree of vacuum in the treatment tank 10, the temperature of the laminate 55a, and the pressing force applied to the laminate 55a during the production of the separator assembly 51. FIG. [Figure 11] FIG. 11 is a cross-sectional view of a laminate 55a before the start of heating and pressing treatment. [Figure 12] FIG. 11 is a cross-sectional view of a laminate 55a after completion of the heating and pressing process. [Figure 13] 2 is a cross-sectional view of a separator assembly 51. FIG. [Figure 14] 1 is an explanatory diagram for explaining the relationship between the distance from the surface of a plate 71 in a separator assembly 51 and the composition ratio of iron, carbon, nickel, and chromium. FIG. [Figure 15] 7 is an explanatory diagram for explaining the relationship between the distance from the surface of a separator assembly made of a metal block of the same material as plate 71 and the composition ratio of iron, carbon, nickel and chromium. FIG. [Figure 16] FIG. 11 is an explanatory diagram for explaining the relationship between the distance from the surface of a plate 71 and the composition ratio of iron, carbon, nickel, and chromium in a separator assembly manufactured by reducing the upper limit of the pressing force applied to a stack 55b to a pressing force P1. [Figure 17] 16 is an explanatory diagram for explaining the relationship between the distance from the surface of the separator assembly in which the surface of the metal block in the example shown in FIG. 15 is carbon-coated, and the composition ratio of iron, carbon, nickel, and chromium. FIG. [Figure 18] FIG. 2 is a cross-sectional view of a separator assembly 51A. [Figure 19] FIG. 4 is a cross-sectional view of a separator assembly 51B. [Figure 20] FIG. 2 is a plan view of the conductive packing P. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, embodiments of a separator manufacturing method, a fuel cell manufacturing method, and a separator manufacturing apparatus will be described with reference to the accompanying drawings.

[0025] First, the configuration of a separator manufacturing apparatus 1 will be described with reference to the accompanying drawings.

[0026] The separator manufacturing apparatus 1 shown in FIG. 1 is an example of a "separator manufacturing apparatus" and is configured to be capable of manufacturing a separator assembly 51 (see FIG. 2) and the like in accordance with a "separator manufacturing method" described below.

[0027] In this case, the separator assembly 51 is an example of a "fuel cell separator" and, together with separators 52a, 52b and MEAs 53, 53, constitutes a fuel cell 50, which is an example of a "fuel cell", as shown in Fig. 2. Specifically, the separator assembly 51 is integrally formed with a separator 61a through which hydrogen gas, which is an example of a "power generation gas", is passed, a separator 61b through which air (atmosphere), which is another example of a "power generation gas", is passed, and a separator 62 through which a cooling fluid (air (atmosphere) as an example) for cooling both separators 61a, 61b is passed.

[0028] Separators 61a and 61b are formed by integrating plates 71 to 73 with a carburized portion 71c formed on one surface of plate 71, and separator 62 is formed by integrating plates 81 and 82. In separator assembly 51 of this example, the plates 71 to 73, 81, and 82 correspond to "plurality of plates" and are formed into a rectangular shape in plan view from thin flat plates of austenitic stainless steel (e.g., SUS316L, SUS316, SUS304).

[0029] Plate 71 is an example of a "first metal plate" and, as shown in FIG. 3, has a plurality of through holes 71a formed therein that form flow paths for passing hydrogen gas as the "power generation gas", air as the "power generation gas", and air as the "cooling fluid", as well as a plurality of slits 71b formed therein that are an example of "slits extending in the plate thickness direction".

[0030] 4, similar to the through holes 71a in the plate 71, a plurality of through holes 72a are formed that form flow paths for hydrogen gas as the "power generation gas", air as the "power generation gas", and air as the "cooling fluid", and a plurality of through holes 72b are formed to connect ends of adjacent slits 71b in the plate 71 and to connect the through holes 71a and the slits 71b. Note that in this plate 72, a blocking portion 72c that overlaps with the slit 71b of the plate 71 when the plate 72 is placed on the plate 71 corresponds to a "blocking portion that blocks one side of the slit in the plate thickness direction".

[0031] In the separators 61a, 61b, grooves H61 (see FIG. 13), which are an example of a "groove for passing the power generation gas", are formed by the slits 71b of the plate 71 and the closed portions 72c of the plate 72. The plate 73 has a plurality of through holes 73a formed therein that form flow paths for hydrogen gas as the "power generation gas", air as the "power generation gas", and air as the "cooling fluid", similar to the through holes 71a, 72a in the plates 71, 72, as shown in FIG.

[0032] As shown in FIG. 6, plate 81 is formed with a plurality of through holes 81a that form flow paths for hydrogen gas as the "power generation gas", air as the "power generation gas", and air as the "cooling fluid", similar to the through holes 71a-73a in plates 71-73, and also with a plurality of slits 81b that form a "groove portion (not shown) for passing the cooling fluid" in combination with a blocking portion 82c in plate 82 described below.

[0033] 7, plate 82 is formed with a plurality of through holes 82a that form flow paths for hydrogen gas as the "power generation gas", air as the "power generation gas", and air as the "cooling fluid", similar to the through holes 71a-73a, 81a in plates 71-73, 81, and also with a plurality of through holes 82b that connect the ends of adjacent slits 81b in plate 81 and connect through holes 81a and slits 81b. Note that in this plate 82, as described above, blocking portion 82c that overlaps with slit 81b of plate 81 when plate 82 is stacked on plate 81 functions as a "blocking portion" that blocks one end of slit 81b in the plate thickness direction.

[0034] 2, the separators 52a, 52b which constitute the fuel cell 50 in combination with the separator assembly 51 are configured by integrating a plate 91 having a carburized portion 91c formed on one surface thereof similar to the plate 71 in the separators 61a, 61b, a plate 92 configured similar to the plate 72 in the separators 61a, 61b, and a plate 93 configured similar to the plate 73 in the separators 61a, 61b. In the separators 61a, 61b of this example, each of the plates 91 to 93 is formed in a rectangular shape in a plan view from a thin flat plate of austenitic stainless steel (e.g., SUS316L, SUS316, SUS304).

[0035] The MEA 53 is a membrane electrode assembly for a fuel cell that is formed by stacking an electrode catalyst, an electrolyte membrane, a gas diffusion layer, etc., and is formed in a rectangular shape in a plan view, similar to the separators 61a, 61b, 62, 52a, and 52b. Note that the specific configuration of the "MEA (membrane electrode assembly for a fuel cell)" in the "fuel cell" is publicly known, so a detailed description will be omitted.

[0036] 1, the separator manufacturing apparatus 1 is configured to include a treatment tank 10, a vacuum pump 11, a control valve 12, a nitrogen tank 13, a heater 14, a blower 15, a pressurizing mechanism 16, an operation unit 17, a display unit 18, a control unit 19, and a storage unit 20. The treatment tank 10 is an example of a "treatment tank", and is configured as a pressure-resistant and heat-resistant container capable of accommodating a treatment target such as a laminate 55b described below, the heater 14, the pressurizing mechanism 16, and the like.

[0037] The vacuum pump 11 increases the degree of vacuum (vacuum pressure) in the treatment tank 10 by exhausting the air in the treatment tank 10 under the control of the control unit 19. The control valve 12 is disposed in an introduction pipe that introduces nitrogen from the nitrogen tank 13 to the treatment tank 10, and reduces the degree of vacuum (vacuum pressure) in the treatment tank 10 by introducing nitrogen into the treatment tank 10 under the control of the control unit 19. The nitrogen tank 13 contains industrial nitrogen that has been dehumidified so that the absolute humidity is sufficiently low. In the separator manufacturing apparatus 1 of this example, the vacuum pump 11, the control valve 12, and the nitrogen tank 13 work together to form a "vacuum adjustment unit."

[0038] The heater 14, in cooperation with the blower 15, constitutes a "temperature adjustment unit" and is housed in the treatment tank 10 as described above, and heats (increases the temperature of) the laminate 55b described below housed in the treatment tank 10 under the control of the control unit 19. The blower 15, under the control of the control unit 19, blows nitrogen introduced from the nitrogen tank 13 into the treatment tank 10 toward the laminate 55b on which a diffusion bonding process described below has been completed, thereby uniformly lowering the temperature of the entire laminate 55b.

[0039] Pressurizing mechanism 16 is an example of a "pressurizing unit" and includes an actuator 16a that pressurizes stack 55b accommodated in treatment tank 10 in the thickness direction of each of plates 71-73, 81, 82. Operation unit 17 includes operation switches for setting the manufacturing conditions for separator assembly 51, etc., by separator manufacturing apparatus 1 and for instructing start and interruption of processing, and outputs operation signals in response to switch operations to control unit 19. Display unit 18 displays a display screen for setting the operating conditions for separator manufacturing apparatus 1 and a display screen showing the operating state of separator manufacturing apparatus 1.

[0040] The control unit 19 performs overall control of the separator manufacturing apparatus 1. The control unit 19 is an example of a "control unit" and controls the vacuum pump 11 to exhaust the air from the treatment tank 10, controls the heater 14 to increase the temperature of the laminate 55b, and controls the pressurizing mechanism 16 (actuator 16a) to pressurize the laminate 55b. The control unit 19 also controls the control valve 12 to introduce nitrogen into the treatment tank 10, and controls the blower 15 to blow nitrogen toward the laminate 55b. The memory unit 20 stores an operation program for the control unit 19, operation conditions of the separator manufacturing apparatus 1, and the like.

[0041] Next, an example of the "separator manufacturing method" and the "fuel cell manufacturing method" will be described with reference to the attached drawings.

[0042] In manufacturing the separator assembly 51 using the separator manufacturing apparatus 1, first, the above-mentioned plates are stacked to produce the laminate 55b shown in FIG. 9. Specifically, the above-mentioned plates 71-73, 81, and 82 and the carbon sheet Sc shown in FIG. 8 are prepared. In this case, the carbon sheet Sc corresponds to a "carbon sheet" and is formed into a rectangular shape in plan view similar to the plates 71-73, 81, and 82 by cutting a graphite sheet (for example, "PERMA-FOIL (registered trademark)" manufactured by Toyo Tanso Co., Ltd.) having a thickness in the range of 0.1 mm to 2.0 mm. Next, as shown in the figure, the carbon sheet Sc, plate 71, plate 72, plate 73, plate 82, plate 81, plate 73, plate 72, plate 71, and carbon sheet Sc are stacked in this order. This completes the laminate 55b.

[0043] In this case, stack 55b is an example of a "second stack", and in the configuration example of stack 55b, lower plates 71-73, plates 81, 82, and upper plates 71-73 in the figure correspond to "plurality of plates", and stack 55a obtained by stacking these corresponds to the "first stack". In stack 55a constituting stack 55b, the surfaces of both plates 71, 71 (the upper surface of upper plate 71 and the lower surface of lower plate 71 in the figure) correspond to "at least one surface".

[0044] Next, a door (not shown) of the treatment tank 10 is opened, and the laminate 55b is placed in the treatment tank 10 and set in the pressurizing mechanism 16 as shown in Fig. 1, and then the door is closed. It is assumed that the treatment conditions for the following treatments performed in the separator manufacturing apparatus 1 are preset and the treatment condition data are stored in the memory unit 20.

[0045] Next, the operator operates the operation unit 17 to instruct the start of the process. In response to this, the control unit 19 executes the following processes in this order according to the above process condition data: "first process" for increasing the degree of vacuum in the process tank 10; "second process" for increasing the temperature of the laminate 55b to a "predetermined first temperature" to reduce and remove the passivation film of each of the plates 71-73, 81, 82; "third process" for increasing the temperature of the laminate 55b to a "predetermined second temperature" in a state in which the laminate 55b is pressurized with a "predetermined pressure" to diffusion bond each of the plates 71-73, 81, 82; and "fourth process" for decreasing the temperature of the laminate 55b and decreasing the degree of vacuum in the process tank 10 to return it to atmospheric pressure.

[0046] 10, at time t0 when an instruction to start processing is given by operating operation unit 17, control unit 19 controls actuator 16a to pressurize stack 55b in the thickness direction of each plate with a pressing force P1 that does not cause any misalignment between the plates of stack 55b. Next, control unit 19 starts the "first processing" at time t1 when the pressure applied by pressurizing mechanism 16 reaches pressing force P1, and controls vacuum pump 11 to exhaust air from within processing tank 10 (to draw a vacuum), thereby increasing the degree of vacuum within processing tank 10 from atmospheric vacuum V0 to a preset vacuum V1.

[0047] Next, the control unit 19 starts the "second process" at time t2 when the degree of vacuum V1 is reached in the process tank 10, and controls the heater 14 to raise the temperature of the stack 55b to the "predetermined first temperature". In this case, the plates 71-73, 81, and 82 constituting the stack 55a in the stack 55b have a passivation state (oxide film) on their surfaces, and the presence of this passivation state may be a factor in inhibiting diffusion bonding, reducing the bonding strength of the plates 71-73, 81, and 82, or making it difficult to form a suitable carburized layer on the surface of the plate 71, which will be described later. In addition, in a state in which the plates 71-73, 81, and 82 have a passivation state (oxide film), even if they can be bonded with a certain degree of bonding strength, the electrical resistance value is high due to the presence of the passivation state, and the electrical characteristics of the separator assembly 51 to be manufactured may be degraded.

[0048] Here, the applicant has confirmed that the passivation occurring in the austenitic stainless steel (for example, SUS316L) used in this example can be suitably reduced and removed to a degree that does not cause the above-mentioned manufacturing problems or significant deterioration of electrical characteristics by maintaining a heated state at a temperature in the range of 680°C to 800°C for a certain period of time. Therefore, the control unit 19 heats the stack 55b to a temperature Tb (an example of the "predetermined first temperature") within the above-mentioned temperature range by the heater 14, and maintains the state for a period of time T1 from a time t3 when the temperature of the stack 55b reaches the temperature Tb, thereby sufficiently reducing and removing the passivation film of each of the plates 71 to 73, 81, and 82.

[0049] Moreover, as an example, at time t2 when the above-mentioned "second process" is started, the control unit 19 controls the actuator 16a to pressurize the laminate 55b in the thickness direction of each plate with a pressing force P2 (an example of a "predetermined pressing force") suitable for the diffusion bonding process described below.

[0050] On the other hand, at time t4 when the above-mentioned time T1 has elapsed, the control unit 19 starts the above-mentioned "third process" and controls the heater 14 to raise the temperature of the laminate 55b to a temperature Tc (an example of a "predefined second temperature higher than the first temperature") suitable for the diffusion bonding process while maintaining the state in which the pressure mechanism 16 presses the laminate 55b. The control unit 19 also maintains this state for time T2 from time t5 when the temperature of the laminate 55b reaches temperature Tc. As a result, the plates 71 to 73, 81, and 82 are diffusion bonded together and integrated as if they were a single metal block (diffusion bonding process).

[0051] In this case, in this example, the laminate 55b, which is a laminate of the plates 71 to 73, 81, and 82, is treated in the treatment tank 10, with the carbon sheets Sc laminated on one side (the surface of the lower plate 71 shown in FIG. 9: the lower side) and the other side (the surface of the upper plate 71 shown in FIG. 9: the upper side) of the laminate 55a. Therefore, in the above-mentioned diffusion bonding process, the carbon sheet Sc laminated on the laminate 55a is pressed against the laminate 55a (plate 71) with a pressing force P2 in a state in which the temperature of the laminate 55a is raised to the temperature Tc together with the laminate 55a. As a result, the carbon in the carbon sheet Sc is carburized into the plate 71, and the carburized portion 71c (an example of the "carburized portion": see FIGS. 12 and 13) described later is formed on the surfaces of the plates 71, 71 (both the front and back sides of the laminate 55a).

[0052] Next, at time t6 when the above-mentioned time T2 has elapsed, the control unit 19 starts the above-mentioned "fourth process", controls the heater 14 to stop heating the laminate 55b, controls the blower 15 to start blowing air to lower the temperature of the laminate 55b, controls the vacuum pump 11 to stop exhaust (vacuum drawing), and controls the control valve 12 to introduce nitrogen from the nitrogen tank 13 into the treatment tank 10 to lower the degree of vacuum in the treatment tank 10.

[0053] In this case, unlike the manufacturing method of this example, when air (atmosphere) is introduced into the treatment tank 10 instead of nitrogen to reduce the degree of vacuum in the treatment tank 10, the oxygen contained in the introduced air may come into contact with the high-temperature laminate 55b, oxidizing the side surface of the laminate 55b and the inner wall surface of the flow path formed by the through holes 71a-73a, 81a, 82a, etc., and may form an oxide film on these parts. Therefore, in the "fourth treatment", it is preferable to introduce "a stable gas (nitrogen in this example) that has a low oxygen content and does not adversely affect the surrounding environment" into the treatment tank 10 so that a large amount of oxygen does not come into contact with the laminate 55b during the temperature decrease.

[0054] Furthermore, as an example, at time t6 when the above-mentioned "fourth process" is started, the control unit 19 controls the actuator 16a to gradually reduce the pressing force applied to the laminate 55b. Thereafter, at time t7 when the inside of the processing tank 10 reaches a vacuum degree V0 under atmospheric pressure and the temperature of the laminate 55b has dropped to a sufficiently low temperature Ta (a temperature at which an oxide film is unlikely to form when the laminate 55b comes into contact with oxygen in the air and at which workers will not be burned when handling the laminate 55b), the door of the processing tank 10 is opened and the laminate 55b is taken out. With the above, a series of processes by the separator manufacturing apparatus 1 is completed.

[0055] Next, a "fifth treatment" is carried out to remove the carbon sheet Sc remaining on the plates 71, 71 in the laminate 55b which has been taken out of the treatment tank 10 after the "fourth treatment".

[0056] Specifically, in stack 55b when stacked in treatment tank 10 at the start of a series of treatments by separator manufacturing apparatus 1 as described above, carbon sheet Sc is superimposed on stack 55a so as to be in close contact with one surface of plate 71, as shown in Fig. 11. By treating stack 55b in treatment tank 10 of separator manufacturing apparatus 1 as described above, plates 71-73, 81, 82 constituting stack 55a are diffusion-bonded and integrated as described above, and carbon in carbon sheet Sc carburizes the surface of stack 55a (plate 71), forming carburized portion 71c on the surface side of stack 55a (plate 71), as shown in Fig. 12.

[0057] Furthermore, the carbon sheet Sc remaining on the laminate 55a (plate 71) without being carburized (hereinafter, the remaining carbon sheet Sc is also referred to as the carbon sheet Sca in order to distinguish it from the carbon sheet Sc before the start of the treatment) is hardened by the pressure applied by the pressurizing mechanism 16 and the heating by the heater 14, and is in a very brittle state. Furthermore, when the carbon sheet Sca remains on the laminate 55a (plate 71), the groove portion H61 formed by the slit 71b of the plate 71 and the blocking portion 72c of the plate 72 is in a state of being blocked by the carbon sheet Sca. Therefore, when the fuel cell 50 is manufactured using the laminate 55b in such a state, hydrogen gas or air as the "power generation gas" that is passed through the groove portion H61 does not come into contact with the MEA 53, that is, power generation is inhibited.

[0058] Therefore, by performing the "fifth process", the carbon sheet Sca is removed from the laminate 55b to expose the groove H61, as shown in FIG. 13. At this time, the carbon sheet Sca is removed by performing a blasting process in which grinding media is sprayed onto the remaining surface of the carbon sheet Sca, a polishing process in which the remaining surface of the carbon sheet Sca is polished using a paste or sheet-like abrasive, and a peeling process in which the carbon sheet Sca is peeled off using a scraper or the like. When removing unnecessary carbon sheet Sca, it is preferable to adopt a method that can process the laminate 55b without excessively increasing the temperature, and to avoid the occurrence of cracks due to partial temperature increase. With the above, the "fifth process" is completed, and the separator assembly 51 is completed.

[0059] The separators 52a, 52b used in the manufacture of the fuel cell 50 can be manufactured by carrying out the same series of processes from the "first process" to the "fifth process" in the manufacture of the separator assembly 51. In this case, when the separators 52a, 52b are manufactured, instead of the plates 71-73, 81, 82 and the carbon sheet Sc used in the manufacture of the separator assembly 51, a stack of plates 91-93 and the carbon sheet Sc (not shown: another example of the "second stack") is placed in the treatment tank 10 of the separator manufacturing apparatus 1, and a series of processes from the "first process" to the "fourth process" are carried out, and then the stack removed from the treatment tank 10 is subjected to the "fifth process".

[0060] On the other hand, when manufacturing the fuel cell 50, the separator assembly 51 manufactured as described above, the separators 52a and 52b, and the two MEAs 53 manufactured in advance are prepared. The separator assembly 51, the separators 52a and 52b, and the two MEAs 53 are the minimum elements necessary to configure the fuel cell 50, and when actually manufacturing the "fuel cell", in addition to these elements, various components according to the use of the "fuel cell" are prepared and integrated. Next, as shown in FIG. 2, the separator 52a, the MEA 53, the separator assembly 51, the MEA 53, and the separator 52b are stacked together, and as an example, the separator assembly 51, the separators 52a and 52b, and the MEAs 53 and 53 are positioned and fixed with bolts / nuts (not shown) while sandwiched between a pair of pressing plates (not shown). This completes the fuel cell 50. Note that a power generation module (power generation section in a fuel cell) manufactured using this fuel cell 50 may incorporate current collector plates, heat sinks, and the like (not shown) depending on its specifications, but detailed explanation of these elements will be omitted.

[0061] In this case, in the separator assembly 51 manufactured according to the above manufacturing method, the plates 71-73, 81, 82, which are the constituent materials, have sufficient hardness and toughness, so that they are less likely to break when subjected to vibration or impact compared to carbon molded products. In addition, in this separator assembly 51, the plates 71-73, 81, 82 are bonded with sufficient bonding strength by diffusion bonding, and the plates 71-73, 81, 82 are integrated as if they were composed of a single metal block. Therefore, even if the separator assembly 51 is manufactured using plates 71-73, 81, 82 that are relatively thin, the rigidity of the separator assembly 51 as a whole can be sufficiently high. The same applies to the separators 52a and 52b in this respect.

[0062] Furthermore, in the separator assembly 51 and the separators 52a, 52b manufactured according to the above manufacturing method, the passivation film is preferably removed in the "second treatment", so that not only can the plates be preferably bonded in the diffusion bonding in the "third treatment", but also, since there is no passivation in the separator assembly 51 and the separators 52a, 52b as a finished product, their electrical resistance is small, so that a product with sufficiently good electrical properties can be provided.

[0063] Furthermore, in the separator assembly 51 and separators 52a, 52b manufactured according to the above manufacturing method, in the "third treatment", the carbon sheet Sc is pressed against the plates 71, 91 in a state where the entire stack 55b is heated to temperature Tc, so that the carbon of the carbon sheet Sc penetrates the plates 71, 91, thereby forming carburized portions 71c, 91c on the surfaces of the plates 71, 91. Specifically, as shown in Fig. 14, in the separator assembly 51 manufactured according to the above manufacturing method, the presence of the carburized portion 71c makes the carbon composition ratio sufficiently high from the surface of the plate 71 to a sufficient depth. In addition, in this figure and in Figures 15 to 17 referred to later, for each depth [μm] from the surface of the object, the "proportion occupied by carbon (C)" is indicated by a solid line L1, the "proportion occupied by iron (Fe)" is indicated by a dashed line L2, the "proportion occupied by nickel (Ni)" is indicated by a dotted line L3, and the "proportion occupied by chromium (Cr)" is indicated by a roughly dashed line L4.

[0064] Therefore, in this separator assembly 51, the electrical resistance of the surface portion of the plate 71 in contact with the MEA 53 when assembled into the fuel cell 50 is sufficiently low, making it possible to provide a product with sufficiently high electrical properties. Also, the carburized portion 71c present on the surface portion of the separator assembly 51 (plate 71) functions as a protective layer, making it difficult for oxidation of iron, chromium, nickel, and the like to proceed on the surface portion.

[0065] In contrast, for example, a "separator assembly" manufactured by forming "grooves" by cutting or etching a metal plate (SUS316L plate material) of the same material as the plates 71-73, 81, and 82 used in manufacturing the separator assembly 51, and bonding the plate with a conductive adhesive, that is, a metallic "separator assembly" manufactured without carrying out the above-mentioned "first treatment" to "fifth treatment", has sufficient hardness, rigidity, and toughness like the separator assembly 51. However, since the above-mentioned "second treatment" is not carried out in the manufacturing process, a passivation state (a chromium oxide film) is generated on the surface of the metal plate. Therefore, the presence of this passivation state increases the electrical resistance of the surface of the "separator assembly", making it difficult to provide a product with good electrical properties. Also, unlike the separator assembly 51 described above, as shown in FIG. 15, although a very small amount of naturally contained carbon is present on its surface, the amount is so small that the reduction in electrical resistance due to the presence of carbon and the effect of inhibiting the oxidation of iron, chromium, nickel, and the like cannot be expected.

[0066] In the manufacturing method of the separator assembly 51 described above, the "third process" is performed in a state where the laminate 55b is pressurized to the pressing force P2 to diffusion-bond the plates 71-73, 81, and 82. However, the applicant has confirmed that the plates 71-73, 81, and 82 can be suitably bonded even when the "third process" diffusion bonding process is performed in a state where the laminate 55b is pressurized with a weak pressing force equivalent to the pressing force P1 instead of such a manufacturing method. Also, as shown in FIG. 16, even when the pressing force of the laminate 55b during the "third process" is weakened, the carbon of the carbon sheet Sc can be penetrated into the plate 71 to form the carburized portion 71c to a sufficient depth. Therefore, the separator assembly manufactured by such a manufacturing method can provide a product with sufficiently high electrical properties like the separator assembly 51, and can suppress the progress of oxidation of iron, chromium, nickel, and the like in the surface area.

[0067] On the other hand, when the surface of the separator assembly described with reference to FIG. 15 is carbon-coated (for example, a process for forming a carbon coating by sputtering), the ratio of carbon can be increased to a sufficient depth on the surface side, as shown in FIG. 17. This allows the electrical resistance of the surface portion of the separator assembly, i.e., the carbon coating portion, to be sufficiently reduced, and the presence of a protective layer formed by the carbon coating allows the progress of oxidation of iron, chromium, nickel, and the like to be sufficiently suppressed. However, in a separator assembly manufactured by such a manufacturing method, the metal mass existing under the carbon coating is the same as that of the separator assembly described with reference to FIG. 15, and the surface of this metal mass is in a passive state (a layer of chromium oxide) with high electrical resistance. This makes it difficult to provide a product with good electrical properties, even though the resistance of the surface portion is low.

[0068] Thus, in this separator manufacturing method, a laminate 55a is formed by stacking plates 71 to 73, 81, and 82 in the thickness direction, the laminate 55a including at least a plate 71 having a slit 71b penetrating therethrough in the thickness direction and a plate 72 having a blocking portion 72c blocking one end of the slit 71b in the thickness direction, and a carbon sheet Sc is laminated on both sides of the laminate 55a in the thickness direction. The laminate 55a is placed in a treatment tank 10 to increase the degree of vacuum in the treatment tank 10. A "first treatment" is performed in which the temperature of the laminate 55b is increased to a predetermined temperature Tb to reduce the passivation film of the plates 71 to 73, 81, and 82. a "second process" to remove the carburized portions 71a and 71b from the laminate 55a; a "third process" to raise the temperature of the laminate 55b to a predetermined temperature Tc higher than temperature Tb while pressurizing the laminate 55b with a predetermined pressing force P2, thereby diffusion bonding the plates 71-73, 81, and 82; and a "fourth process" to lower the temperature of the laminate 55b and reduce the degree of vacuum in the treatment tank 10, thereby producing a separator assembly 51 in which groove portions H61 through which the "power generation gas" passes are formed by the slits 71b and the blocking portions 72c, and in which carburized portions 71c are formed on both sides of the laminate 55a.

[0069] In addition, in this fuel cell manufacturing method, a fuel cell 50 is manufactured by sandwiching an MEA 53 between a separator assembly 51 and separators 52a, 52b manufactured by the above-mentioned separator manufacturing method, and integrating the separator assembly 51, the separators 52a, 52b, and the MEA 53. The separator manufacturing apparatus 1 further comprises a treatment tank 10 capable of accommodating the above-mentioned laminate 55b, a vacuum pump 11, a control valve 12 and a nitrogen tank 13 for adjusting the degree of vacuum within the treatment tank 10, a heater 14 and a blower 15 for adjusting the temperature of the laminate 55b accommodated within the treatment tank 10, a pressurizing mechanism 16 for pressurizing the laminate 55b accommodated within the treatment tank 10 in the thickness direction, and a control unit 19 for controlling the operation of the vacuum pump 11, the control valve 12, the heater 14, the blower 15 and the pressurizing mechanism 16 (actuator 16a), and the control unit 19 performs the above-mentioned "first process", "second process", "third process" and "fourth process" in this order to manufacture the separator assembly 51.

[0070] Therefore, according to the separator manufacturing method, fuel cell manufacturing method, and separator manufacturing apparatus 1, a separator assembly 51 having sufficiently high hardness, rigidity, and toughness can be manufactured by using a metal plate as a material, compared with a carbon separator manufactured by a molding method using a mixture of a carbon resin material formed by applying a thermosetting resin material to the surface of carbon powder to form a coating layer, and a liquid such as water, and kneading the mixture as a molding material. This makes it possible to provide a separator assembly 51 and a fuel cell 50 that are less likely to be damaged due to vibration or impact. In addition, since it is not necessary to make the thickness of each part excessively thick in order to ensure the physical strength of the separator assembly 51, the separator assembly 51 and the fuel cell 50 can be sufficiently miniaturized. In addition, since it is not necessary to design the shape taking into account demolding (removal from the mold after molding is completed), the degree of freedom in design is sufficiently high, and the separator assembly 51 and the fuel cell 50 can be manufactured in any shape according to the required power generation capacity and use. Furthermore, the presence of carburized portion 71c on the surface portion sufficiently reduces the electrical resistance of the portion in contact with MEA 53, making it possible to provide a separator assembly 51 with excellent electrical properties and a fuel cell 50 with sufficiently high power generation efficiency. Also, the carburized portion 71c functions as a protective layer, making it possible to provide a product with excellent corrosion resistance.

[0071] In addition, in this separator manufacturing method, when separator assembly 51 is manufactured using stack 55b in which carbon sheet Sc is layered on stack 55a in which plates 71-73, 81, 82 are layered so that one side is formed by plate 71, a "fifth process" is performed to remove the carbon sheet Sca that remains on plate 71 without being carburized in stack 55b that has completed the "fourth process", thereby exposing groove portion H61.

[0072] Therefore, according to this separator manufacturing method and fuel cell manufacturing method, a series of processes from the "first process" to the "fourth process" can be performed on the laminate 55b in which the carbon sheet Sc of sufficient thickness is laminated on the laminate 55a, on the premise that the carbon sheet Sca remains after the completion of the "fourth process". This makes it possible to avoid the occurrence of a portion where the carburized portion 71c is not formed suitably due to the occurrence of a tear in the carbon sheet Sc before the completion of the "fourth process", and to suitably form the carburized portion 71c over the entire area of ​​the portion where the carbon sheet Sc is laminated. In addition, since the surface flatness of the separator aggregate 51 can be sufficiently improved when the remaining carbon sheet Sca is removed, the separator aggregate 51 can be suitably attached to other laminates in the laminate (fuel cell 50) including this separator aggregate 51. This makes it possible to suitably avoid a situation where the "power generation gas" leaks.

[0073] In addition, in this separator manufacturing method, nitrogen is introduced from the nitrogen tank 13 into the treatment tank 10 in the "fourth treatment" to reduce the degree of vacuum in the treatment tank 10. Therefore, in this separator manufacturing method and fuel cell manufacturing method, unlike a manufacturing method in which air (atmosphere) is introduced into the treatment tank 10 to reduce the degree of vacuum, the amount of oxygen that comes into contact with the laminate 55b heated to a high temperature in the "third treatment" can be sufficiently reduced, and it is possible to suitably avoid a situation in which the surface of the laminate 55b is oxidized and a passivation film is formed. In addition, since "nitrogen" is relatively inexpensive, has low danger at high temperatures, and is harmless even if released into the atmosphere when the door of the treatment tank 10 is opened after the treatment is completed, it is possible to avoid a rise in the manufacturing cost of the separator assembly 51, an accident during manufacturing, and environmental destruction.

[0074] In addition, in the fourth treatment, the temperature of the stack 55b is lowered by blowing gas in the treatment tank 10 toward the stack 55b with the blower 15. Therefore, according to this separator manufacturing method and fuel cell manufacturing method, the amount of temperature drop in each part of the stack 55b can be made uniform, and the thermal contraction state of each part can be made similar, so that unintended deformation or cracks in the separator assembly 51 can be preferably avoided.

[0075] It should be noted that the specific contents of the "separator manufacturing method" and "fuel cell manufacturing method" and the configuration of the "separator manufacturing apparatus" are not limited to the above-mentioned exemplary contents and configurations.

[0076] For example, the configuration and method for manufacturing the separator assembly 51 in which three separators 61a, 61b, and 62 are integrated by processing the laminate 55b in which two sets of plates 71-73, plates 81 and 82, and two carbon sheets Sc are stacked in the processing tank 10 has been described as an example, but a manufacturing method can also be adopted in which the separator 61a (another example of a "separator") and the separator assembly 60 in which the separator 61b and the separator 62 are integrated are separately manufactured, and then the separator assembly 51A shown in Fig. 18 is integrated by sandwiching the conductive packing P therebetween. Also, a manufacturing method can be adopted in which the separator 61a, the separator 61b, and the separator 62 (each another example of a "separator") are separately manufactured, and then the separator assembly 51B shown in Fig. 19 is integrated by sandwiching the conductive packing P therebetween.

[0077] In this case, the manufacturing method of the separator 61a and the separator assembly 60 constituting the separator assembly 51A and the manufacturing method of each of the separators 61a, 61b, and 62 constituting the separator assembly 51B are the same as the manufacturing method of the separator assembly 51 described above, so detailed description will be omitted. The conductive packing P is a sheet body formed of an elastic resin material having conductivity and heat resistance and chemical resistance, and through holes Pa are formed in accordance with the formation positions of the through holes 71a to 73a, 8a, and 82a in each of the plates 71 to 73 and the plates 81 and 82 as shown in Fig. 20. In the separator assemblies 51A and 51B manufactured according to such a manufacturing method, the carburized parts 71c and 91c are formed in the plates 71 and 91, so that the same effect as the separator assembly 51 described above can be achieved.

[0078] In addition, the method of performing a series of processes from the "first process" to the "fourth process" in a state where the carbon sheet Sc is disposed on each of the surfaces of both plates 71, 71 in the laminate 55a as "at least one surface" and then performing the "fifth process" to remove the carbon sheet Sc remaining on the plates 71, 71 without being carburized has been described as an example, but for example, when manufacturing the separator assembly 51A, a laminate of the plates 71 to 73 is made into a "first laminate", and a series of processes from the "first process" to the "fourth process" are performed in a state where the carbon sheet Sc is disposed on each of the surfaces of the plates 71, 73 in this "first laminate", and then performing the "fifth process" to remove the carbon sheet Sc remaining on the plates 71, 73 without being carburized can also be adopted. In this manufacturing method, the plate 73 corresponds to the "plate other than the first metal plate among the plurality of plates".

[0079] According to such a separator manufacturing method, a series of processes from the "first process" to the "fourth process" can be performed on the "second laminate" in which a carbon sheet Sc of sufficient thickness is laminated on the "first laminate" on the premise that the carbon sheet Sca remains after the completion of the "fourth process", so that the carbon sheet Sc can be torn before the completion of the "fourth process" to avoid the occurrence of portions on the plates 71, 73 where the "carburized portion" is not formed suitably, and the "carburized portion" can be suitably formed over the entire area of ​​the portion where the carbon sheet Sc is laminated. In addition, since the surface flatness of the "separator assembly" can be sufficiently improved when the remaining carbon sheet Sca is removed, the "separator assembly" can be suitably attached to other laminates in the laminate (fuel cell) including this "separator assembly". This can suitably avoid the occurrence of a situation where the "power generation gas" leaks. [Explanation of symbols]

[0080] 1 Separator manufacturing equipment 10 Treatment tank 11 Vacuum Pump 12 Control valve 13 Nitrogen Tank 14 Heater 15 Blower 16 Pressurizing mechanism 16a Actuator 17 Control section 18 Display 19 Control section 20 Memory section 50 Fuel Cell 51, 51A, 51B, 60 Separator assembly 52a, 52b, 61a, 61b, 62 Separator 53 MEA 55a, 55b Laminate 71~73,81,82,91~93 Plates 71a~73a,81a,82a,Pa through hole 71b,81b Slit 71c,91c Carburized part 72b,82b through hole 72c,82c Occlusion H61 Groove P Conductive packing P0,P1 Pressing force Sc, Sca carbon sheet Ta~Tc temperature V0,V1 Vacuum degree

Claims

1. A method for manufacturing a separator for a fuel cell having grooves for passing a power generation gas therethrough, comprising the steps of: A first laminate is formed by stacking a plurality of plates in a thickness direction, the first laminate including at least a first metal plate having a slit penetrating therethrough in a thickness direction and a second metal plate having a blocking portion for blocking one end of the slit in the thickness direction. The first laminate is formed by stacking a plurality of plates in a thickness direction, the first laminate being formed by stacking a carbon sheet on at least one surface in the thickness direction of the first laminate, and the second laminate is placed in a treatment tank. a first process for increasing the degree of vacuum in the processing tank; a second process for reducing and removing the passivation film of the plurality of plates by increasing the temperature of the second stack to a predetermined first temperature; a third process of increasing a temperature of the second stack to a predetermined second temperature higher than the first temperature while pressing the second stack with a predetermined pressure, thereby diffusion bonding the plurality of plates; a fourth process for lowering the temperature of the second stack and lowering the degree of vacuum in the treatment tank in that order, thereby manufacturing the fuel cell separator in which the groove portion is formed by the slit and the blocking portion and a carburized portion is formed on at least one of the surfaces of the first stack.

2. 2. The separator manufacturing method according to claim 1, wherein, when manufacturing the fuel cell separator using the second stack in which the carbon sheet is layered on the first stack in which the plurality of plates are layered so that at least one of the surfaces is formed by the first metal plate, a fifth process is carried out to remove the carbon sheet remaining on the first metal plate in the second stack after the fourth process has been completed, thereby exposing the groove portion.

3. 2. The separator manufacturing method of claim 1, wherein, when manufacturing the fuel cell separator using the second stack in which the carbon sheet is stacked on the first stack in which the plurality of plate bodies are stacked such that at least one surface is formed by a plate body other than the first metal plate, a fifth process is performed to remove the carbon sheet that remains without being carburized on the plate bodies other than the first metal plate in the second stack that has completed the fourth process.

4. 2. The method for producing a separator according to claim 1, wherein in the fourth treatment, nitrogen is introduced into the treatment tank to reduce the degree of vacuum in the treatment tank.

5. 2. The method for producing a separator according to claim 1, wherein in the fourth treatment, a gas in the treatment tank is blown toward the second laminate to lower the temperature of the second laminate.

6. 6. A method for manufacturing a fuel cell, comprising: sandwiching a fuel cell membrane electrode assembly between a plurality of fuel cell separators manufactured by the separator manufacturing method according to any one of claims 1 to 5; and integrating the fuel cell separators and the fuel cell membrane electrode assembly in a state in which the fuel cell separators and the fuel cell membrane electrode assembly are integrated to manufacture a fuel cell.

7. A separator manufacturing apparatus for manufacturing a separator for a fuel cell having a groove portion for allowing a power generation gas to pass therethrough, comprising: a treatment tank capable of accommodating a second laminate in which a carbon sheet is laminated on at least one surface in the thickness direction of a first laminate in which a plurality of plates including at least a first metal plate having a slit penetrating therethrough in a thickness direction and a second metal plate having a blocking portion for blocking one side of the slit in the thickness direction are laminated in the thickness direction; a vacuum adjustment unit for adjusting the degree of vacuum in the treatment tank; a temperature adjusting unit that adjusts the temperature of the second laminate contained in the treatment tank; a pressurizing unit that presses the second laminate contained in the treatment tank in the plate thickness direction; a control unit for controlling operations of the vacuum adjustment unit, the temperature adjustment unit, and the pressurization unit; The control unit is a first process of increasing a degree of vacuum in the process tank in which the second laminate is accommodated by controlling the vacuum adjustment unit; a second process in which the temperature of the second stack is increased to a predetermined first temperature by controlling the temperature adjusting unit to reduce and remove the passivation film of the plurality of plates; a third process of controlling the temperature adjustment unit to increase the temperature of the second laminate to a predefined second temperature higher than the first temperature while the second laminate is pressed by the pressurizing unit with a predefined pressure, thereby diffusion bonding the plurality of plates; a fourth process of controlling the temperature adjustment unit to lower the temperature of the second stack and controlling the vacuum adjustment unit to lower the vacuum in the treatment tank in that order, thereby manufacturing the fuel cell separator in which the groove portion is formed by the slit and the blocking portion and a carburized portion is formed on at least one of the surfaces of the first stack.

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