JP2007287362A - Fuel cell component and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell component that has a corrosion-resistant coating film including an alumite layer and a polyimide resin layer at least a part of the surface of an aluminum base-material, and a fuel cell component manufacturing method that enables to almost uniformly form the polyimide resin layer with a sufficient film thickness above the alumite layer. <P>SOLUTION: The alumite layer is formed by applying anodic oxidation to the aluminum base-material composed of an aluminum-based material. Next, a zinc-plating layer is formed on the alumite layer by applying zinc plating. Then, an intermediate metal layer including nickel as a main component is formed on the zinc plating layer by applying plating mainly composed of nickel. Subsequently, a gold-plating layer is formed on the intermediate metal layer by applying gold plating. Finally, the polyimide (PI) resin layer is formed on the gold-plating layer by applying electrodeposition coating using a polyimide electrodeposition paint. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell component having a corrosion-resistant coating on at least a part of the surface of an aluminum substrate made of an aluminum-based material, and a method for manufacturing such a fuel cell component.

  In general, a fuel cell is composed of a fuel cell stack in which battery cells and separators are alternately arranged and stacked and held between a pair of end plates via a terminal plate and an insulating plate. In the case of a polymer electrolyte fuel cell, the battery cell is configured by sandwiching a solid polymer membrane made of a proton-permeable polymer material between an air-side electrode and a hydrogen-side electrode that have both gas permeability and conductivity. Has been. In the fuel cell stack, a gas flow passage is defined by a separator or the like. With the operation of the fuel cell, corrosive substances (for example, hydrogen fluoride) are volatilized from the battery cell or part of it is dissolved in moisture, and corrosive gas and corrosive liquid (acidic water) are generated. It is known that they corrode the metal parts that make up the gas flow path. For this reason, improving the corrosion resistance of the contact part with gas etc. in the metal parts constituting the fuel cell is an important technical problem.

  Conventionally, an iron-based material having a certain corrosion resistance such as stainless steel has been studied as a base material (base material) of a metal part constituting a fuel cell. However, since iron-based materials generally have a large specific gravity, they are inherently disadvantageous when it is desired to reduce the weight, such as in-vehicle fuel cells. Therefore, it has been studied to produce a fuel cell component using a relatively inexpensive light metal such as aluminum. However, aluminum generally has a drawback that it is easily corroded by an acid or the like and has low corrosion resistance. Alumite treatment (anodizing treatment) is known as a technique for improving the corrosion resistance of aluminum materials, but an alumite layer (ie, an aluminum oxide film) alone is sufficient to withstand the severe corrosive environment inside the fuel cell. Corrosion resistance cannot be ensured. For this reason, in a fuel cell component having an aluminum-based material as a base material, it has been proposed to further form a polymer film on the alumite layer obtained by anodizing the base material.

  In Patent Document 1, an alumite film is formed on the surface of a separator substrate made of aluminum or an alloy thereof by an anodic oxidation method, and a polymer heat resistant film (for example, vinyl resin or polyimide) is further formed on the alumite film. A fuel cell separator is disclosed. According to Patent Document 1, by forming a polymer heat resistant coating on the alumite coating, deterioration of the alumite coating due to water vapor or the like is suppressed, and the corrosion resistance of the separator is improved.

  Patent Document 2 discloses a “coated anodized layer having a polyimide coating” in which a polyimide coating is formed by electrodeposition on an anodized aluminum surface. According to Patent Document 2, it is possible to provide an alumite product excellent in corrosion resistance and insulation by providing an alumite having a polyimide film that penetrates into the porosity.

Japanese Patent No. 3387046 (paragraphs 0019 to 0029) Japanese Unexamined Patent Application Publication No. 2004-59997 (Summary, column of effects of invention)

  Patent Document 2 proposes to form a polyimide resin layer on the alumite by electrodeposition, but since the conductivity of the anodized itself is very poor, the polyimide resin layer having a necessary film thickness on the alumite by the electrodeposition method. It is difficult in the first place to form a uniform. Incidentally, according to the experiments of the present inventors, the polyimide film thickness obtained when the polyimide resin layer was directly formed on the alumite surface by electrodeposition was less than 10 μm (see Comparative Example 1 described later). Therefore, even if a corrosion-resistant coating composed of an alumite layer and a polyimide resin layer is formed on an aluminum substrate according to Patent Document 2, only a polyimide resin layer with insufficient film thickness and uniformity can be obtained. Has the fundamental problem that it is difficult to achieve the intended purpose. The present invention has been made in view of such circumstances.

  An object of the present invention is a method of manufacturing a fuel cell component having a corrosion-resistant coating film including an alumite layer and a polyimide resin layer on at least a part of the surface of an aluminum base material made of an aluminum-based material, and above the anodized layer Another object of the present invention is to provide a method of manufacturing a fuel cell component capable of forming a polyimide resin layer having a sufficient film thickness almost uniformly. In addition, a fuel cell component having a corrosion-resistant coating having sufficient corrosion resistance to withstand a severe corrosive environment inside the fuel cell is provided on at least a part of the surface of an aluminum base material made of an aluminum-based material. It is to provide.

  The present invention relates to a method for producing a fuel cell component having a corrosion-resistant coating on at least a part of the surface of an aluminum base material made of an aluminum-based material, and the aluminum base material is subjected to anodization. An anodic oxidation step of forming an alumite layer on the surface of the substrate, and a galvanization step of forming a galvanization layer on the anodized layer by galvanizing the anodized aluminum substrate; An intermediate metal layer forming step of forming an intermediate metal layer containing nickel as a main component on the zinc plating layer by performing nickel-based plating on the galvanized aluminum base, and nickel-based plating A noble metal layer that forms a noble metal layer on the intermediate metal layer by performing plating or sputtering of the noble metal on the aluminum base material to which the metal is applied And a polyimide electrodeposition step of forming a polyimide resin layer on the noble metal layer by applying an electrodeposition coating using a polyimide electrodeposition coating to an aluminum substrate subjected to noble metal plating or sputtering, and Are sequentially performed. A method for manufacturing a fuel cell component.

  In this manufacturing method, the noble metal layer forming step performs gold (Au) plating on the aluminum base material plated with nickel, thereby forming a gold plating layer on the intermediate metal layer. It is preferable that it is a gold plating process to be formed. In the polyimide electrodeposition process, it is desirable to form a polyimide resin layer having a thickness of at least 20 μm.

  Furthermore, the present invention is a fuel cell component having a corrosion-resistant coating on at least a part of the surface of an aluminum substrate made of an aluminum-based material, wherein the corrosion-resistant coating is formed on the surface of the aluminum substrate by anodic oxidation. An anodized layer, a galvanized layer formed on the anodized layer, an intermediate metal layer formed on the galvanized layer and containing nickel as a main component, and formed on the intermediate metal layer A fuel cell component comprising a noble metal layer and a polyimide resin layer having a film thickness of at least 20 μm formed on the noble metal layer. The noble metal layer is preferably a gold plating layer.

  The significance of each constituent element in the present invention, further preferred aspects of the present invention, and additional constituent elements will be further described in the section of “Best Mode for Carrying Out the Invention” below.

  According to the method of manufacturing a fuel cell component of the present invention, the upper layer of the alumite layer formed on the surface of the aluminum base material by anodic oxidation includes a galvanized layer, an intermediate metal layer containing nickel as a main component, and a noble metal layer. After forming a multi-layered metal layer, electrodeposition coating using a polyimide electrodeposition coating is applied. That is, at the time of polyimide electrodeposition, the conductivity of the surface of the aluminum substrate is sufficiently ensured by the multilayer metal layer, and the electrodeposition of the polyimide electrodeposition paint is performed smoothly and reliably. Therefore, according to the method of the present invention, a polyimide resin layer having a sufficient thickness can be formed almost uniformly above the alumite layer. As a result, the alumite layer and the alumite layer are formed on at least a part of the surface of the aluminum substrate. A fuel cell component having a corrosion-resistant coating including a sufficiently thick polyimide resin layer can be reliably produced.

  According to the fuel cell component of the present invention, a multilayer comprising an alumite layer formed on the surface of an aluminum substrate by anodization, and further comprising a zinc plating layer, an intermediate metal layer containing nickel as a main component, and a noble metal layer The metal layer and a polyimide resin layer having a film thickness of at least 20 μm are laminated to form a corrosion-resistant film. In other words, the corrosion-resistant film on the surface of the aluminum base material is a polyimide resin layer having a sufficient thickness located in the uppermost layer, a multi-layer metal layer (especially a noble metal layer among them), and an alumite layer below it. It has a triple corrosion resistant barrier. Therefore, according to the fuel cell component of the present invention, it is possible to exhibit sufficient corrosion resistance that can withstand the severe corrosive environment inside the fuel cell.

  The fuel cell component of the present invention has a corrosion-resistant coating on at least a part of the surface of an aluminum substrate made of an aluminum-based material. Examples of the fuel cell component include a separator for configuring a fuel cell stack, a terminal plate (terminal plate), an end plate, or piping components such as gas for a fuel cell. The “at least part of the surface of the aluminum base” means part or all of the surface of the aluminum base.

  Examples of the aluminum-based material constituting the aluminum substrate include pure aluminum (Al), Al—Mg, Al—Si, Al—Mg—Si, Al—Mn, and Al—Zn. . The aluminum base material may be a casting as well as a rolled material of an aluminum-based material. The shape of the aluminum base material is not limited, and may be any shape such as a flat plate shape, a curved plate shape, a disc shape, an annular shape, a cylindrical shape, or a pipe shape.

  Corrosion-resistant coating that occupies at least a part of the surface of the aluminum substrate includes an anodizing step, a step of forming a multi-layered metal layer (zinc plating step, intermediate metal layer forming step and noble metal layer forming step), and polyimide electrodeposition It forms through a process in order.

  Anodization process: Anodization of aluminum substrate is achieved by electrolytic treatment with aluminum substrate as anode and counter electrode as cathode while aluminum substrate and counter electrode are immersed in acid or alkali solution. Is done. By anodizing, formation of an oxide film (alumite layer) on the surface of the aluminum substrate is promoted. It is preferable to form an alumite layer having an average film thickness of 1 to 20 μm (micrometer) on the surface of the aluminum substrate by anodization. When the average film thickness of the alumite layer is less than 1 μm, there is no significant difference from the film thickness of the oxide film on the surface of the aluminum base material that is naturally formed in the atmosphere, and it does not contribute much to the prevention of elution of the metal constituting the base material. On the other hand, even if the average film thickness of the alumite layer exceeds 20 μm, it only takes time for anodization, and the elution prevention effect of the base metal constituting metal is not much different from that in the case of 20 μm or less.

  Since the alumite layer is formed by anodizing an aluminum base material, it has a surface roughness (that is, a fine pore structure) peculiar to anodization. At this stage, the alumite layer is not sealed, and an alumite layer with fine pores remaining is provided for the next step.

  Zinc plating step: A zinc plating layer is formed on the anodized layer by applying zinc plating to the anodized aluminum base material. This galvanized layer is an intervening layer or an adhesion reinforcing layer for enabling a metal layer to be laminated on the alumite. That is, the oxide film (alumite layer) formed on the surface of the aluminum substrate becomes a marginal factor when the metal plating layer is formed by electroless plating or electrolytic plating. Therefore, for example, the surface of the substrate is treated with a treatment solution for galvanizing to induce a substitution reaction between aluminum oxide and zinc (Zn), thereby forming a galvanized layer on the surface of the alumite layer. By forming such a zinc plating layer (zinc displacement plating layer), various metal layers can be easily formed thereon by electroless plating or electrolytic plating.

  Intermediate metal layer forming step: An intermediate metal layer containing nickel as a main component is formed on the zinc plated layer by performing nickel-based plating on the zinc-plated aluminum base material.

  The intermediate metal layer on the galvanized layer is a layer containing nickel (Ni) as a main component. “Nickel is included as a main component” means that the intermediate metal layer is formed of a multilayer structure of a nickel layer and another metal layer as well as the intermediate metal layer formed of nickel or an alloy thereof or a nickel solid solution. It is meant to include cases. The basic role of the intermediate metal layer is to improve the adhesion strength between the two layers by being interposed between the galvanized layer immediately below it and the noble metal layer directly above. That is, even if a noble metal layer is laminated directly on the galvanized layer, delamination is likely to occur at the boundary or interface between the two layers, and sufficient adhesion strength cannot be obtained. For this reason, an intermediate metal layer containing nickel as a main component, which exhibits a certain adhesion to both zinc and noble metal, is interposed. Further, since nickel has better leveling properties than other metals, when a layer containing nickel as a main component is formed by electroplating, a hard and highly smooth surface can be formed. If the hardness and smoothness of the upper surface of the intermediate metal layer are high, the film thickness of the noble metal layer formed on the intermediate metal layer can be kept to the minimum necessary level, and the amount of noble metal used can be reduced to reduce manufacturing costs. It becomes easy to plan.

  The intermediate metal layer preferably has a two-layer structure of a copper layer formed on the galvanized layer and a nickel layer formed on the copper layer. That is, the copper layer is interposed between the galvanized layer and the nickel layer. Since copper (Cu) has a high affinity for both zinc (Zn) and nickel (Ni), it has a Zn / Cu / Ni laminated structure compared to the case where a nickel layer is formed directly on a galvanized layer. However, the adhesion strength between the galvanized layer and the intermediate metal layer is further increased. When the intermediate metal layer has a two-layer structure of a copper layer and a nickel layer, it is preferable to form each of the copper layer and the nickel layer by strike plating which is a kind of electroplating. According to strike plating, adhesion of metal ions like electroless plating is suppressed and the rate of adhesion like electrolytic plating increases, so that the metal purity of each plating layer increases.

  When the intermediate metal layer includes a nickel layer, the nickel layer can also function as a barrier layer that suppresses metal diffusion. That is, diffusion of zinc or copper metal atoms may occur in layers below the nickel layer, but since the nickel layer has a barrier property that prevents the diffusion of zinc or copper, the lower layer of zinc or copper may be The diffusion to the upper noble metal layer is prevented. Therefore, the purity or metal composition of the noble metal constituting the noble metal layer is hardly disturbed by the diffusion metal, and the noble metal layer can maintain the expected corrosion resistance effect for a long time.

  In addition, about the said nickel layer in case the said intermediate metal layer consists of nickel layers, and the said nickel layer in case the said intermediate metal layer consists of two layers, a copper layer and a nickel layer, sulfur (S) content differs. You may comprise with the "multilayer nickel plating layer" which piled up several nickel membranes. As a configuration form of this multilayer nickel plating layer, a semi-bright nickel layer containing almost no sulfur is arranged in the first layer (lower layer) and a bright nickel containing a small amount of sulfur in the second layer (upper layer) thereabove. A nickel plating layer having a two-layer structure in which layers are arranged, and a high sulfur content nickel strike layer interposed between a first layer (lower layer) of semi-bright nickel and a second layer (upper layer) of bright nickel A nickel plating layer having a layer structure can be exemplified. By the way, the sulfur content of high-sulfur nickel strike is on the order of 0.1%, the sulfur content of bright nickel is on the order of 0.01%, and the sulfur content of semi-bright nickel is 0.001%. Below order.

  Generally, in a nickel coating, the natural potential tends to decrease as the sulfur content increases. For this reason, in the case of a nickel plating layer having a two-layer structure, even if the corrosion area reaches the lower semi-bright nickel, the lower semi-bright nickel is bright nickel due to the potential relationship between the bright nickel and the semi-bright nickel. Corrosion in the direction of the substrate is mitigated due to the anode corrosion protection. In the case of a nickel plating layer with a three-layer structure, the natural potential between the three layers has a relationship of middle layer (high sulfur-containing nickel strike) <upper layer (bright nickel) <lower layer (semi-bright nickel). Even if it reaches the lower-layer semi-bright nickel, the corrosion of the lower layer (semi-bright nickel) is greatly mitigated by the preferential corrosion of the most basic high sulfur content nickel strike. Thus, the corrosion resistance can be further improved by configuring the nickel layer constituting the intermediate metal layer as a multilayer nickel plating layer.

  Precious metal layer forming step: A precious metal layer is formed on the intermediate metal layer by performing precious metal plating or sputtering on an aluminum base material plated with nickel. Examples of the plating method include electroless plating or electrolytic plating (including strike plating which is a kind of electrolytic plating).

  Examples of the noble metal constituting the noble metal layer include gold (Au), platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and the like. As the noble metal constituting the noble metal layer, gold (Au) or platinum (Pt) is particularly preferable, and gold (Au) is most preferable. These noble metals are corrosion resistant metals that are not easily attacked by corrosive substances such as acids. For this reason, the noble metal layer located directly under the polyimide resin layer, combined with the corrosion resistance of the polyimide resin, imparts further excellent corrosion resistance to the fuel cell component. Further, since the plating layer of noble metal selected from gold (Au) or platinum (Pt) is a good conductor, it provides a very convenient electrodeposition environment when the polyimide resin layer is formed by electrodeposition. This greatly contributes to the thickening of the resin layer.

  Incidentally, when the average thickness of the anodized layer formed by anodic oxidation is 1 to 20 μm, the thickness of the galvanized layer is preferably 0.005 to 0.1 μm (5 to 100 nm). The film thickness is preferably 0.1 to 10 μm, and the film thickness of the noble metal layer is preferably 0.001 to 0.1 μm (1 to 100 nm).

  As described above, the anodized layer is accompanied by a surface roughness (that is, a fine pore structure) peculiar to anodization. By applying the zinc plating and nickel-based plating to the anodized layer, In addition, an intermediate metal layer containing zinc as a main component enters and forms in the fine holes of the alumite, and this creates an anchor effect for the alumite layer of the multilayer metal layer. Therefore, in addition to adhesion strengthening based on a chemical approach by layering three layers of a zinc plating layer, an intermediate metal layer containing nickel as a main component, and a noble metal layer on the anodized layer, the anchor Since physical (or mechanical) adhesion reinforcement due to the effect is achieved, the adhesion of the multilayer metal layer to the alumite layer is very high. In this sense, it can be said that it is very reasonable to form a multi-layered metal layer by a series of plating processes after anodizing of the aluminum base.

  Polyimide electrodeposition process: A polyimide resin layer is formed on the noble metal layer by applying an electrodeposition coating using a polyimide electrodeposition coating to an aluminum base material plated or sputtered with a noble metal.

  As an electrodeposition coating method, a negative voltage is applied to an aluminum base material (coating object) that has been plated or sputtered with a noble metal, and a positively polarized polyimide electrodeposition paint is deposited on the surface of the noble metal layer. It is very preferable to use a coating method.

  As a polyimide electrodeposition paint used for electrodeposition coating, a cationic polyimide electrodeposition paint mainly composed of polyimide having a chemical structure as shown in Chemical Formula 1 is most preferable. In Chemical Formula 1, R means an alkyl chain, and Ar means an aromatic structure. The dielectric breakdown voltage of this cationic polyimide electrodeposition coating is about 1000 V, and has extremely high electrical insulation. Moreover, the glass transition temperature of this cationic polyimide electrodeposition coating is about 200 ° C. (DSC measurement), and the 5% mass reduction temperature is about 400 ° C. (TGA measurement). As an organic polymer, it has extremely high heat resistance. is there.

  Cationic electrodeposition coating using a cationic polyimide electrodeposition coating on a precious metal plated or sputtered aluminum substrate, and then heat-fixing the polyimide electrodeposition coating to the substrate (substrate) Is preferred. The conditions for electrodeposition coating, the pre-treatment and post-treatment methods for the object to be coated, and the heat-fixing conditions for the electrodeposition paint are appropriately selected according to the type and properties of the electrodeposition paint used.

  Polyimide (PI) resin itself has high corrosion resistance, but the corrosion resistance is further enhanced by the cooperation of the polyimide resin layer and the noble metal layer directly therebelow. Furthermore, in the present invention, a multilayer metal layer having relatively excellent conductivity is formed in advance on the surface of the aluminum base material to be coated during polyimide electrodeposition, and the presence of this metal layer facilitates the polyimide electrodeposition. And since it is performed reliably and the polyimide resin layer of sufficient film thickness is formed substantially uniformly, the corrosion resistance of an aluminum base material is improved remarkably compared with the past.

  In addition, the film thickness of a polyimide resin layer needs at least 20 micrometers. On the other hand, the practical upper limit of the film thickness of the polyimide resin layer is 40 μm, preferably 35 μm or less. That is, the film thickness of the polyimide resin layer is 20 to 40 μm (preferably 20 to 35 μm).

  The corrosion resistant coating of fuel cell components made through the above series of steps (anodizing step, galvanizing step, intermediate metal layer forming step and noble metal layer forming step) is anodized on the surface of the aluminum substrate by anodization. A layer, a galvanized layer formed on the anodized layer, an intermediate metal layer containing nickel as a main component formed on the galvanized layer, and a noble metal layer formed on the intermediate metal layer And a polyimide resin layer having a film thickness of at least 20 μm formed on the noble metal layer. In other words, the corrosion-resistant film on the surface of the aluminum base material is a polyimide resin layer having a sufficient thickness located in the uppermost layer, a multi-layer metal layer (especially a noble metal layer among them), and an alumite layer below it. Since it has a triple corrosion resistant barrier, it can exhibit sufficient corrosion resistance to withstand the severe corrosive environment inside the fuel cell.

  Example 1 which is a specific example of the present invention will be described in comparison with Comparative Examples 1 and 2. In addition, the plate-like aluminum base material described below is a corrosion resistance test piece assuming a fuel cell component.

[Example 1]
JIS: A plate-like aluminum base material (90 mm long x 50 mm wide x 1 mm thick), which is a rolled material of A1100 series aluminum, is prepared, anodized and multilayered under the conditions described below. Corrosion resistance test pieces of Example 1 were obtained by sequentially performing metal plating and polyimide electrodeposition.

(1) Anodization An electrolytic bath was prepared by adding a small amount of a surfactant to a 15% sulfuric acid aqueous solution, and the bath temperature was adjusted to about 20 ° C. The plate-like aluminum substrate and the carbon counter electrode were immersed in this electrolytic bath. The plate-like aluminum substrate is connected to the anode (+ electrode) of the DC power supply, the counter electrode is connected to the cathode (−electrode) of the DC power supply, and a voltage of 15 volts is applied between the electrodes for 25 minutes. Went. By this anodic oxidation, an oxide film (alumite layer) having a film thickness of 5 μm was formed on the surface of the plate-like aluminum substrate. In addition, the base material after anodic oxidation is only sufficiently washed with ion-exchanged water, and the sealing treatment of the alumite layer is not performed.

(2) Multi-layer metal plating As a first plating step, a plate-like aluminum substrate having an alumite layer formed on the surface is immersed in a galvanizing solution (an aqueous solution containing zinc oxide, sodium hydroxide, Rochelle salt, etc.). As a result, zinc substitution plating was performed on the surface of the alumite layer to form a Zn plating layer. As a second plating step, the plate-like aluminum substrate subjected to zinc substitution plating is immersed in a nickel plating treatment solution (an aqueous solution containing nickel sulfamate, nickel chloride, boric acid, etc.), so that the Zn plating layer is formed. A nickel plating layer was formed by performing nickel plating on the top. As a third plating step, the Ni plating layer is obtained by immersing a nickel-plated plate-like aluminum substrate in a gold plating treatment solution (an aqueous solution containing gold cyanide, sodium cyanide, potassium carbonate, etc.). An Au plating layer was formed by performing gold plating on the substrate. Thus, a multilayer metal plating layer comprising three layers of Zn (film thickness: 50 nm) / Ni (film thickness: 5 μm) / Au (film thickness: 10 nm) on the surface of the oxide film (alumite layer) of the plate-like aluminum base material. (See FIGS. 1 and 2). In addition, the base material after completion of multilayer metal plating was sufficiently washed with ion-exchanged water.

(3) Polyimide electrodeposition Prepare a water bath in which a cationic polyimide electrodeposition paint (Shimizu Corporation product: Elecoat PI) is diluted to an appropriate concentration with ion-exchanged water in an electrodeposition bath, and the bath temperature is about 25 ° C. It was adjusted. The polyimide electrodeposition coating water bath is immersed in the plate-like aluminum base material after the above-mentioned multilayer metal plating, and the plate-like aluminum base material is connected to the negative electrode (-electrode) of the DC power supply device and is made of carbon soaked in the water bath. The counter electrode was connected to the positive electrode (+ electrode) of the DC power supply, and electrodeposition was performed at a current density of 5 mA / cm ² and a voltage of 200 volts for about 2 minutes. Then, the plate-shaped aluminum base material taken out from the electrodeposition tank was washed with water, and pre-dried (about 110 ° C. for 15 minutes) after air blowing. And it moved to the heating apparatus, and the baking process (about 210 degreeC for 30 minutes) of the polyimide electrodeposition coating material was performed. Thus, a polyimide (PI) resin layer (film thickness: 30 μm) was formed on the Au plating layer which is the uppermost layer of the multilayer metal plating (see FIG. 1).

  The corrosion resistance test piece of Example 1 obtained in this way was formed on the surface of an aluminum base material with an alumite layer (film thickness: 5 μm), a Zn plating layer, a Ni plating layer, an Au plating layer, and a polyimide resin layer (film thickness). : 30 μm).

[Comparative Example 1]
A plate-like aluminum substrate made of the same A1100 series aluminum as in Example 1 was prepared, and this plate-like aluminum substrate was anodized under the same conditions as in Example 1. Then, polyimide electrodeposition was applied to the plate-like aluminum base material subjected to this anodic oxidation in the same manner as in Example 1. Note that, under the same electrodeposition conditions as in Example 1, a polyimide resin layer having a film thickness of 8 μm was formed on the base oxide film (alumite layer). The corrosion resistance test piece of Comparative Example 1 obtained in this way is obtained by laminating an alumite layer (film thickness: 5 μm) and a polyimide resin layer (film thickness: 8 μm) on the surface of an aluminum base material.

[Comparative Example 2]
A plate-like aluminum substrate made of the same A1100 aluminum as in Example 1 was prepared, and polyimide electrodeposition was directly applied to the plate-like aluminum substrate in the same manner as in Example 1. A polyimide resin layer having a film thickness of 28 μm was formed on the substrate under the same electrodeposition conditions as in Example 1. The corrosion resistance test piece of Comparative Example 2 obtained in this way is obtained by forming a polyimide resin layer (film thickness: 28 μm) as a single layer on the surface of an aluminum substrate.

[Acid corrosion durability test]
The following tests were performed on the test pieces of Example 1 and Comparative Examples 1 and 2. That is, a low concentration hydrofluoric acid aqueous solution was prepared in a transparent test water tank, and temperature control was performed so that the temperature of the hydrofluoric acid aqueous solution was maintained at 80 ° C. Then, the time from when each test piece was immersed in an aqueous hydrofluoric acid solution until the occurrence of blister (swelling) in the surface coating of the test piece was visually observed was measured. A blister is a bulge of a coating produced as a result of hydrogen gas being generated as a hydrofluoric acid aqueous solution enters between an aluminum substrate and a polyimide resin layer. Then, the relative evaluation indicating the number of times until the blister occurrence in each of Example 1 and Comparative Example 1 as a reference value “1” as a reference value “1” as a reference value “1”. went. The relative evaluation results are shown in Table 1 together with the measured values of the thickness of the polyimide resin layer.

  As can be seen by comparing the relative evaluation of the swelling of Comparative Example 1 and Comparative Example 2 in Table 1, when a single layer of polyimide resin layer is formed on the surface of the aluminum substrate, regardless of the thickness of the polyimide resin layer Rather, the corrosion resistance to hydrofluoric acid is clearly higher when the alumite layer and the polyimide resin layer are laminated on the surface of the aluminum substrate. Further, as can be seen by comparing the relative evaluation of the swelling of Example 1 and Comparative Example 1, an alumite layer and a polyimide resin layer are formed in comparison with the case where two layers of an alumite layer and a polyimide resin layer are formed on the surface of an aluminum substrate. In the case where a multilayer metal layer (Zn / Ni / Au) is additionally formed therebetween, the corrosion resistance against hydrofluoric acid is further improved. The reason why the corrosion resistance of Example 1 was superior to that of Comparative Example 1 was formed by electrodeposition by forming a multi-layer metal layer (Zn / Ni / Au) having high conductivity on the alumite layer. Two factors are that the film thickness of the polyimide resin layer is significantly thicker than in the case of Comparative Example 1 and that the Au plating layer located directly under the polyimide resin layer is useful for improving the corrosion resistance. This is considered to be due to the synergistic effect of.

1 is a schematic cross-sectional view showing an outline of a laminated structure of a corrosion resistant film in Example 1. FIG. FIG. 2 is an enlarged schematic cross-sectional view showing a part of FIG. 1.

Claims (5)

A method of manufacturing a fuel cell component having a corrosion-resistant coating on at least a part of the surface of an aluminum base material made of an aluminum-based material,
Anodizing the aluminum substrate to form an alumite layer on the surface of the aluminum substrate;
A galvanizing step for forming a galvanized layer on the anodized layer by galvanizing the anodized aluminum base;
An intermediate metal layer forming step of forming an intermediate metal layer containing nickel as a main component on the galvanized layer by performing nickel-based plating on the galvanized aluminum substrate;
A noble metal layer forming step of forming a noble metal layer on the intermediate metal layer by plating or sputtering a noble metal on an aluminum base material plated with nickel;
A polyimide electrodeposition step of forming a polyimide resin layer on the noble metal layer is sequentially performed by applying an electrodeposition coating using a polyimide electrodeposition coating to an aluminum base material plated or sputtered with a noble metal. A method of manufacturing a fuel cell component.   The noble metal layer forming step is a gold plating step of forming a gold plating layer on the intermediate metal layer by performing gold plating on the aluminum base material plated with nickel. A method for producing a fuel cell component according to claim 1.   3. The method of manufacturing a fuel cell component according to claim 1, wherein in the polyimide electrodeposition step, a polyimide resin layer having a film thickness of at least 20 μm is formed. A fuel cell component having a corrosion-resistant coating on at least a part of the surface of an aluminum substrate made of an aluminum-based material, wherein the corrosion-resistant coating is
An anodized layer formed on the surface of the aluminum substrate by anodization;
A galvanized layer formed on the alumite layer;
An intermediate metal layer formed on the galvanized layer and containing nickel as a main component;
A noble metal layer formed on the intermediate metal layer;
A fuel cell component comprising a polyimide resin layer having a film thickness of at least 20 μm formed on the noble metal layer.   The fuel cell component according to claim 4, wherein the noble metal layer is a gold plating layer.

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