JP4585760B2 - Method for forming noble metal thin film of polymer electrolyte fuel cell separator - Google Patents

Method for forming noble metal thin film of polymer electrolyte fuel cell separator Download PDF

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JP4585760B2
JP4585760B2 JP2003408550A JP2003408550A JP4585760B2 JP 4585760 B2 JP4585760 B2 JP 4585760B2 JP 2003408550 A JP2003408550 A JP 2003408550A JP 2003408550 A JP2003408550 A JP 2003408550A JP 4585760 B2 JP4585760 B2 JP 4585760B2
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noble metal
thin film
metal thin
fuel cell
polymer electrolyte
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JP2005174572A (en
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俊樹 河村
優 小田
健太郎 名越
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Honda Motor Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description

本発明は、固体高分子型燃料電池セパレータに用いる金属薄板の表面処理に係り、特に、金属薄板の表面への貴金属薄膜形成方法に関する。   The present invention relates to surface treatment of a thin metal plate used for a polymer electrolyte fuel cell separator, and more particularly to a method for forming a noble metal thin film on the surface of a thin metal plate.

固体高分子型燃料電池は、平板状の電極構造体(MEA:Membrane Electrode Assembly)の両側にセパレータが積層された積層体が1ユニットとされ、複数のユニットが積層されて燃料電池スタックとして構成される。電極構造体は、正極(カソード)および負極(アノード)を構成する一対のガス拡散電極の間にイオン交換樹脂等からなる電解質膜が挟まれた三層構造である。ガス拡散電極は、電解質膜に接触する電極触媒層と、その外側に設けられたガス拡散層とから構成される。また、セパレータは、電極構造体のガス拡散電極に接触するように積層され、ガス拡散電極との間にガスを流通させるガス流路やセパレータ間に冷媒流路が形成されている。このような燃料電池によると、例えば、負極側のガス拡散電極に面するガス流路に燃料である水素ガスを流し、正極側のガス拡散電極に面するガス流路に酸素や空気等の酸化性ガスを流すと電気化学反応が起こり、電気が発生する。   In the polymer electrolyte fuel cell, a laminated body in which separators are laminated on both sides of a planar electrode structure (MEA) is a single unit, and a plurality of units are laminated to form a fuel cell stack. The The electrode structure has a three-layer structure in which an electrolyte membrane made of an ion exchange resin or the like is sandwiched between a pair of gas diffusion electrodes constituting a positive electrode (cathode) and a negative electrode (anode). A gas diffusion electrode is comprised from the electrode catalyst layer which contacts an electrolyte membrane, and the gas diffusion layer provided in the outer side. In addition, the separator is laminated so as to be in contact with the gas diffusion electrode of the electrode structure, and a gas flow path for allowing gas to flow between the gas diffusion electrode and a refrigerant flow path is formed between the separators. According to such a fuel cell, for example, hydrogen gas, which is a fuel, is allowed to flow in a gas flow channel facing the negative electrode side gas diffusion electrode, and oxygen or air is oxidized in the gas flow channel facing the positive electrode side gas diffusion electrode. When a sex gas is flowed, an electrochemical reaction occurs and electricity is generated.

上記セパレータは、負極側の水素ガスの触媒反応により発生した電子を外部回路へ供給する一方、外部回路からの電子を正極側に送給する集電体としての機能を具備する必要がある。そこで、セパレータには黒鉛系材料や金属系材料からなる導電性材料が用いられており、特に金属系材料のものは、機械的強度に優れている点や、薄板化による軽量・コンパクト化が可能である点で有利であるとされている。金属製のセパレータは、ステンレス鋼やチタン合金等の耐食性を有する金属材料からなる薄板をプレス加工して断面凹凸状に成形したものが挙げられる。図1に、このようなセパレータの一例を示す。   The separator needs to have a function as a current collector that supplies electrons generated by the catalytic reaction of the hydrogen gas on the negative electrode side to the external circuit, and supplies electrons from the external circuit to the positive electrode side. Therefore, conductive materials such as graphite and metal materials are used for the separator. Especially metal materials are excellent in mechanical strength, and can be made lighter and more compact by making them thinner. It is said that it is advantageous at this point. Examples of the metal separator include those formed by pressing a thin plate made of a metal material having corrosion resistance such as stainless steel and titanium alloy so as to have a cross-sectional uneven shape. FIG. 1 shows an example of such a separator.

従来、上記のような耐食性を必要とするセパレータ材料には、ステンレス鋼、ニッケル基合金、チタン、チタン合金等の耐食性に優れた材料をそのまま用いるか、これらに銅、ニッケル、クロム等をメッキして用いており、更に高い耐食性を必要とする場合には、金、銀、白金等の貴金属をメッキして用いるのが一般的であった。   Conventionally, separator materials that require corrosion resistance as described above use materials with excellent corrosion resistance such as stainless steel, nickel-base alloys, titanium, titanium alloys, or are plated with copper, nickel, chromium, etc. When higher corrosion resistance is required, it is common to use a precious metal such as gold, silver or platinum after plating.

このようなメッキ製品を製造する場合、メッキした後に製品を加工するとメッキ膜が金属基材から剥離し易いことから、一般に、金属基材に対して製品の形状を付与する塑性加工を施した後にメッキを行っていた。しかしながら、この場合、金属基材の溝等のエッジ部分にメッキ膜が付き難く、その部分の耐食性に問題を有していた。また、メッキ膜は、微細な空隙を有するポーラス構造であるために、金属基材との密着力が弱いという問題もあった。さらに、メッキ膜には、ポーラス構造に起因するピンホールが形成され易いため、メッキ膜が薄いと耐食性が低くなってしまう。このため、耐食性を高めるためにメッキ膜を厚く形成する必要があり、貴金属メッキの場合にはコストが高くなるという問題があった。   When manufacturing such a plated product, since the plated film is easily peeled off from the metal base material when the product is processed after plating, generally, after performing plastic working to give the shape of the product to the metal base material I was plating. However, in this case, the plating film is difficult to be attached to the edge portion such as the groove of the metal base material, and there is a problem in the corrosion resistance of the portion. In addition, since the plating film has a porous structure having fine voids, there is also a problem that the adhesion with the metal substrate is weak. Further, since pinholes due to the porous structure are easily formed in the plated film, the corrosion resistance is lowered when the plated film is thin. For this reason, in order to improve corrosion resistance, it is necessary to form a thick plating film. In the case of noble metal plating, there is a problem that the cost is increased.

一方、固体高分子型燃料電池用金属セパレータは、単位電池の電極と、その隣り合う単位電池の電極とに電気的に接続され、かつ反応ガスを分離する作用を有することから、反応ガスに対する高いガス気密性が求められるとともに、高い導電性(低い接触電気抵抗)が要求される。また、水素および酸素を酸化還元する際の反応に際して、金属イオンの溶出を充分に抑制することができる高い耐食性を付与する必要がある。   On the other hand, the metal separator for a polymer electrolyte fuel cell is electrically connected to the electrode of the unit cell and the electrode of the adjacent unit cell and has an action of separating the reaction gas, so that it is highly resistant to the reaction gas. Gas tightness is required, and high conductivity (low contact electric resistance) is required. In addition, it is necessary to provide high corrosion resistance that can sufficiently suppress elution of metal ions in the reaction when oxidizing and reducing hydrogen and oxygen.

このような要求に対し、鉄基合金、ニッケル基合金、チタン、チタン基合金等の金属基材の表面上に、金、銀、白金、パラジウム、およびこれらの合金等の貴金属層を形成し、これらを5%以上の圧延率で圧延加工してクラッド化する方法が提案されている(例えば、特許文献1および2参照。)。この方法によれば、鉄基合金等の金属基材の表面上に被覆した貴金属薄膜を、金属材料と共に圧延加工してクラッド化しているため、圧着材と同程度の密着力が得られ、また貴金属層のポーラス構造が緻密化されると共にピンホールが閉孔されるので、耐食性が改善される。したがって、上記貴金属層を薄くすることができ、コスト面でも改善される。また、上記貴金属層が形成されているため、接触電気抵抗を低減することができる。   In response to such a requirement, a noble metal layer such as gold, silver, platinum, palladium, or an alloy thereof is formed on the surface of a metal base material such as an iron base alloy, a nickel base alloy, titanium, or a titanium base alloy, A method has been proposed in which these are rolled at a rolling rate of 5% or more to be clad (see, for example, Patent Documents 1 and 2). According to this method, the noble metal thin film coated on the surface of a metal base material such as an iron-based alloy is clad by rolling with a metal material, so that the same adhesion force as that of a pressure-bonding material can be obtained. Since the porous structure of the noble metal layer is densified and the pinhole is closed, the corrosion resistance is improved. Therefore, the noble metal layer can be thinned and the cost is improved. Further, since the noble metal layer is formed, the contact electric resistance can be reduced.

しかしながら、この方法で金属材料を圧延加工すると、金属基材に加工硬化が生じるため、燃料電池用セパレータ用金属材料にこの方法を適用した場合、燃料ガスおよび酸化性ガスの流通路を形成するために必要な塑性加工性が損なわれる。これに対して、特許文献1および2には、この問題を解決するため、圧延加工によって生じた貴金属層の加工硬化を除去するために熱処理を行うことが提案されている。   However, when a metal material is rolled by this method, work hardening occurs in the metal base material. Therefore, when this method is applied to a metal material for a fuel cell separator, a flow path for fuel gas and oxidizing gas is formed. The plastic workability required for the process is impaired. On the other hand, Patent Documents 1 and 2 propose to perform a heat treatment to remove work hardening of the noble metal layer caused by rolling in order to solve this problem.

特開2002−254180(要約書、0011)JP2002-254180 (abstract, 0011) 特開2002−260681(要約書、0011)JP2002260681 (abstract, 0011)

しかしながら、加工硬化を除去しうる高温の熱処理を適用すると、金属基材との熱拡散により貴金属層が散逸または変質してしまい、さらに、熱処理のための工程が増えて製造コストが割高になるという問題が生じる。   However, if a high-temperature heat treatment that can remove work hardening is applied, the noble metal layer is dissipated or deteriorated due to thermal diffusion with the metal substrate, and further, the number of steps for heat treatment increases and the manufacturing cost is expensive. Problems arise.

本発明は上記事情に鑑みてなされたものであり、金属基材をほとんど加工硬化させることなく耐食性、密着性、接触電気抵抗等が改善され、かつコストの低い固体高分子型燃料電池セパレータの貴金属薄膜形成方法を提供することを目的としている。   The present invention has been made in view of the above circumstances, and the precious metal of the solid polymer fuel cell separator is improved in corrosion resistance, adhesion, contact electric resistance, etc., and is low in cost without almost hardening the metal substrate. It aims at providing the thin film formation method.

本発明の固体高分子型燃料電池セパレータの貴金属薄膜形成方法は、貴金属担持シートの一方の表面に貴金属薄膜を形成し、表面が活性化処理された耐食性金属基材に貴金属担持シートの貴金属薄膜側を接触させて圧着し、続いて貴金属担持シートのみを貴金属薄膜から除去して貴金属薄膜を耐食性金属基材に転写する固体高分子型燃料電池セパレータの貴金属薄膜形成方法であって、圧着を圧延にて行ない、この圧延による金属基材の厚さの減少率が10%未満であることを特徴としている。

The method for forming a noble metal thin film of a polymer electrolyte fuel cell separator according to the present invention is such that a noble metal thin film is formed on one surface of a noble metal carrying sheet, and the surface is activated and the corrosion-resistant metal substrate is activated on the noble metal thin film side of the noble metal carrying sheet A noble metal thin film forming method for a polymer electrolyte fuel cell separator in which only the noble metal carrying sheet is removed from the noble metal thin film and then transferred to the corrosion-resistant metal substrate. The reduction rate of the thickness of the metal substrate by this rolling is less than 10%.

上記構成の固体高分子型燃料電池セパレータの貴金属薄膜形成方法においては、耐食性金属基材の少なくとも一方の表面を活性化処理し、その後貴金属担持シートの貴金属薄膜側と耐食性金属基材の活性化処理を施した側とを接触させ、プレスやロール等によって、互いに圧着する。この場合において、金属基材の表面が活性化処理されているから、貴金属薄膜との密着力が強く、したがって、プレス等による圧着力を小さくして貴金属薄膜が加工硬化を起こさないようにすることができ、続いて燃料ガスおよび酸化性ガスの流通路を形成するために必要な成形加工を施すことができる。さらに、加工硬化が生じないから、加工硬化を除去するための熱処理工程が不要となり、コスト削減の観点からも有効である。また、金属基材と貴金属薄膜との充分な密着力によって、耐食性、接触電気抵抗が改善される。   In the method for forming a noble metal thin film of the polymer electrolyte fuel cell separator having the above structure, at least one surface of the corrosion-resistant metal substrate is activated, and then the activation treatment of the noble metal thin film side of the noble metal-supported sheet and the corrosion-resistant metal substrate. Are brought into contact with each other and pressed against each other with a press or a roll. In this case, since the surface of the metal substrate is activated, the adhesion with the noble metal thin film is strong. Therefore, the pressure bonding force by a press or the like is reduced so that the noble metal thin film does not cause work hardening. Subsequently, the molding process necessary to form the flow paths for the fuel gas and the oxidizing gas can be performed. Furthermore, since work hardening does not occur, a heat treatment step for removing work hardening is unnecessary, which is also effective from the viewpoint of cost reduction. Moreover, corrosion resistance and contact electrical resistance are improved by sufficient adhesion between the metal substrate and the noble metal thin film.

以上説明したように、本発明によれば、加工硬化の原因となる圧延工程を経ることなく耐食性、密着性、接触電気抵抗等が改善され、かつコストの低い固体高分子型燃料電池セパレータの貴金属薄膜形成方法を提供することができる。   As described above, according to the present invention, the noble metal of the solid polymer fuel cell separator is improved in corrosion resistance, adhesion, contact electrical resistance, etc. without undergoing a rolling process that causes work hardening, and is low in cost. A thin film forming method can be provided.

以下、適宜図面を参照しながら、本発明の固体高分子型燃料電池セパレータの貴金属薄膜形成方法を説明する。   Hereinafter, a method for forming a noble metal thin film of a polymer electrolyte fuel cell separator of the present invention will be described with reference to the drawings as appropriate.

1.貴金属薄膜の形成工程
図2は、本発明における貴金属薄膜が形成された貴金属担持シートの概念図である。まず、図2に示すように、貴金属薄膜2を貴金属担持シート1上に形成する。貴金属担持シート1としては、樹脂製、ガラス製や金属製等、あらゆるものが使用可能である。貴金属薄膜2は、ピンホールが充分少なく、かつコスト削減のために貴金属膜厚が充分薄いものが好ましい。貴金属担持シート1上への貴金属薄膜2の形成方法としては、メッキ、蒸着、スパッタイオンプレーティングやCVD等が考えられる。
1. Step of Forming Noble Metal Thin Film FIG. 2 is a conceptual diagram of a noble metal carrying sheet on which the noble metal thin film is formed in the present invention. First, as shown in FIG. 2, the noble metal thin film 2 is formed on the noble metal carrying sheet 1. As the noble metal carrying sheet 1, any material such as resin, glass or metal can be used. The noble metal thin film 2 preferably has a sufficiently small pinhole and a sufficiently thin noble metal film thickness for cost reduction. As a method for forming the noble metal thin film 2 on the noble metal carrying sheet 1, plating, vapor deposition, sputter ion plating, CVD, or the like can be considered.

図4は、本発明における貴金属薄膜が形成された貴金属担持シートの圧延工程を示す概念図である。貴金属薄膜2をさらに薄肉化、あるいは、貴金属薄膜2のピンホール除去など特性改善のため、例えば図4に示すように、貴金属薄膜2と一体化した貴金属担持シート1に圧延等の加工を加えてもよい。この圧延加工によれば、貴金属薄膜2のポーラス構造を緻密化させると共にピンホールを閉孔させることができ、さらに、所望の厚さを有する貴金属薄膜2を形成することができて好適である。   FIG. 4 is a conceptual diagram showing a rolling process of a noble metal carrying sheet on which a noble metal thin film is formed in the present invention. In order to further reduce the thickness of the noble metal thin film 2 or improve characteristics such as pinhole removal of the noble metal thin film 2, for example, as shown in FIG. 4, the noble metal carrying sheet 1 integrated with the noble metal thin film 2 is subjected to processing such as rolling. Also good. According to this rolling process, the porous structure of the noble metal thin film 2 can be densified, the pinhole can be closed, and the noble metal thin film 2 having a desired thickness can be formed.

2.金属基材表面の活性化処理工程
次に、真空中または低圧不活性ガス雰囲気中で、貴金属薄膜2と金属基材4の少なくとも一方の接合面に活性化処理を施す。この活性化処理は、金属基材4と貴金属薄膜2の密着性を高めるための処理である。また、真空中または低圧不活性ガス雰囲気中等の非酸化雰囲気中で活性化処理を行うことにより、活性化された表面が例えば大気中の酸素や水分等から影響を受けず、活性化による効果が次の圧着工程まで持続する。
2. Next, activation processing is performed on at least one joint surface of the noble metal thin film 2 and the metal substrate 4 in a vacuum or in a low-pressure inert gas atmosphere. This activation process is a process for improving the adhesion between the metal substrate 4 and the noble metal thin film 2. In addition, by performing the activation treatment in a non-oxidizing atmosphere such as a vacuum or a low-pressure inert gas atmosphere, the activated surface is not affected by, for example, oxygen or moisture in the atmosphere, and the effect of activation can be obtained. It lasts until the next crimping process.

3.金属基材と貴金属薄膜の圧着工程
図5は、本発明における貴金属薄膜が形成された貴金属担持シートと金属基材との圧着工程の一例を示す概念図である。図5に示すように、金属基材4の活性化処理を施した表面と、貴金属担持シート1上に形成された貴金属薄膜2の表面を接触させ、圧着加工を施すことにより、金属基材4と貴金属薄膜2とを強固に接合することができる。圧着加工法としては、圧延ロールによる圧延加工や、プレス加工等が適用可能であり、特にこれらのみに限定されず、あらゆる圧着加工が適用可能であるが、金属基材の厚さの減少率を10%未満とすることが肝要である。
3. FIG. 5 is a conceptual diagram showing an example of a pressure bonding step between a noble metal carrying sheet on which a noble metal thin film is formed and a metal substrate in the present invention. As shown in FIG. 5, the surface of the metal substrate 4 subjected to the activation treatment and the surface of the noble metal thin film 2 formed on the noble metal carrying sheet 1 are brought into contact with each other and subjected to pressure bonding to thereby form the metal substrate 4. And the noble metal thin film 2 can be firmly bonded. As the crimping method, rolling with a rolling roll, press working, etc. can be applied, not limited to these, and any crimping can be applied, but the reduction rate of the thickness of the metal substrate can be reduced. It is important to make it less than 10%.

4.貴金属担持シート除去工程
上記圧着工程によって金属基材4に貴金属薄膜2を接合した後は、貴金属担持シート1を除去することにより、表面に貴金属薄膜2が設けられた金属基材を得ることができる。この貴金属担持シート1の除去工程の例を図6および7に示す。図6に示すように、溶解エッチングにより貴金属担持シート1を溶解して洗浄する方法が考えられる。また、図7に示すように、貴金属担持シート1を貴金属薄膜2から剥離させてもよい。
4). Noble metal carrying sheet removing step After the noble metal thin film 2 is joined to the metal substrate 4 by the above-described crimping step, the noble metal carrying sheet 1 is removed to obtain a metal substrate with the noble metal thin film 2 provided on the surface. . An example of the removal process of the noble metal carrying sheet 1 is shown in FIGS. As shown in FIG. 6, a method of dissolving and cleaning the noble metal carrying sheet 1 by dissolution etching is conceivable. Further, as shown in FIG. 7, the noble metal carrying sheet 1 may be peeled from the noble metal thin film 2.

5.固体高分子型燃料電池セパレータへの成形工程
上記のようにして得られた貴金属薄膜が表面に一体化した金属基材に、プレス成形加工等を施し、燃料ガスまたは酸化性ガスを通す流通路を形成し、固体高分子型燃料電池用金属セパレータ等に供することができる。そのようなセパレータの一例を、図1に示す。
5). Step of forming into a polymer electrolyte fuel cell separator A metal substrate in which the noble metal thin film obtained as described above is integrated on the surface is subjected to press molding or the like, and a flow passage through which fuel gas or oxidizing gas passes And can be used for a metal separator for a polymer electrolyte fuel cell. An example of such a separator is shown in FIG.

本発明の圧延工程における金属基材の厚さの減少率としては、10%未満が好ましい。10%より大きい場合は、従来技術と同様に金属基材4が加工硬化を起こしてしまい、本発明による効果が得られない。この厚さの減少率は、5%未満であればより好ましい。   The reduction rate of the thickness of the metal substrate in the rolling process of the present invention is preferably less than 10%. If it is larger than 10%, the metal substrate 4 undergoes work hardening as in the prior art, and the effects of the present invention cannot be obtained. The thickness reduction rate is more preferably less than 5%.

上記範囲の圧着力で押圧することにより、金属基材4に加工硬化を起こすことなく金属基材表面に貴金属薄膜2を形成することができる。したがって、後の工程において燃料ガスまたは酸化性ガスを通す流通路を形成するために行う塑性加工性が阻害されない。また、加工硬化を除去するための熱処理も不要になることから、金属基材との熱拡散により貴金属薄膜が散逸・変質するという問題や、熱処理に要する処理コストが割高になるという問題を解決することができて好適である。   By pressing with a pressing force in the above range, the noble metal thin film 2 can be formed on the surface of the metal substrate 4 without causing work hardening on the metal substrate 4. Therefore, the plastic workability performed in order to form the flow path through which the fuel gas or the oxidizing gas passes in the subsequent process is not hindered. In addition, since no heat treatment is required to remove work hardening, it solves the problem that the noble metal thin film is dissipated and deteriorated due to thermal diffusion with the metal substrate, and the processing cost required for the heat treatment is high. This is preferable.

本発明で用いられる金属基材としては、特に限定されず、あらゆる種類の金属を挙げることができるが、固体高分子型燃料電池セパレータとして要求される耐食性、接触電気抵抗等の性能を考慮すると、アルミニウム基合金、ステンレス鋼を含む鉄基合金、ニッケル基合金、チタン基合金等は、それ自体が高い耐食性と低い接触電気抵抗を有していることから、特に好ましい。   The metal substrate used in the present invention is not particularly limited and can include all kinds of metals, but considering the performance such as corrosion resistance and contact electric resistance required as a solid polymer fuel cell separator, Aluminum-based alloys, iron-based alloys including stainless steel, nickel-based alloys, titanium-based alloys and the like are particularly preferable because they themselves have high corrosion resistance and low contact electrical resistance.

本発明で用いられる貴金属薄膜としては、各種の金属が考えられるが、上記の金属基材表面に被覆して耐食性、接触電気抵抗等の性能を向上させる観点から、金、銀、白金、パラジウム、またはこれらの金属の合金等が特に好ましい。   As the noble metal thin film used in the present invention, various metals are conceivable. From the viewpoint of improving the performance such as corrosion resistance and contact electric resistance by coating the surface of the metal substrate, gold, silver, platinum, palladium, Or an alloy of these metals is particularly preferable.

図3は、本発明における貴金属薄膜と貴金属担持シートの間に剥離層を設けた例の概念図である。図3に示すように、貴金属担持シート1と貴金属薄膜2の間に剥離層3が設けられていれば、貴金属担持シート1を貴金属薄膜2から除去する工程において、貴金属薄膜2を損傷することなく貴金属担持シート1の剥離を容易に行うことができて好適である。   FIG. 3 is a conceptual diagram of an example in which a release layer is provided between the noble metal thin film and the noble metal carrying sheet in the present invention. As shown in FIG. 3, if the release layer 3 is provided between the noble metal carrying sheet 1 and the noble metal thin film 2, the noble metal thin film 2 is not damaged in the step of removing the noble metal carrying sheet 1 from the noble metal thin film 2. It is preferable that the noble metal carrying sheet 1 can be easily peeled off.

本発明においては、真空中または不活性ガス雰囲気中で金属基材表面の活性化処理を行っているので、金属基材表面が例えば酸化反応を起こさず、活性化による効果が持続する。この金属基材の表面活性化方法は、特に限定されないが、いわゆるドライエッチング等の方法が好ましく、特にプラズマイオンエッチング法が好ましい。このプラズマイオンエッチングは、アルゴンイオンをプラズマ化し、金属基材表面に高速で衝突させるエッチング方法である。このプラズマイオンエッチングが好ましい理由としては、金属基材表面活性化処理の効率が高く、また、金属基材表面を清浄に処理することが可能だからである。   In the present invention, since the metal substrate surface is activated in a vacuum or in an inert gas atmosphere, the metal substrate surface does not cause, for example, an oxidation reaction, and the effect of activation continues. The surface activation method of the metal substrate is not particularly limited, but a method such as so-called dry etching is preferable, and a plasma ion etching method is particularly preferable. This plasma ion etching is an etching method in which argon ions are turned into plasma and collide with the metal substrate surface at high speed. The reason why this plasma ion etching is preferable is that the metal substrate surface activation treatment is highly efficient and the metal substrate surface can be treated cleanly.

以下、実施例によって本発明を詳細に説明する。
[実施例1]
貴金属担持シートとして38μm厚のPETフィルムを用い、剥離層を介して、真空中でこのPETフィルムに30nm厚の金を蒸着した。一方、金属基材として0.2mm厚のSUS316L材を用い、真空中(真空度:1×10−3Pa)で高周波プラズマイオンエッチングを行った。その後直ちに、SUS316L材の厚さ減少率が0.5%となるように上記金薄膜とSUS316L材を接合した。続いてPETフィルムを剥離し、SUS316L材の表面に30nm厚の金薄膜を転写した。
Hereinafter, the present invention will be described in detail by way of examples.
[Example 1]
A PET film having a thickness of 38 μm was used as a noble metal carrying sheet, and gold having a thickness of 30 nm was deposited on the PET film in a vacuum through a release layer. On the other hand, a SUS316L material having a thickness of 0.2 mm was used as a metal substrate, and high frequency plasma ion etching was performed in a vacuum (degree of vacuum: 1 × 10 −3 Pa). Immediately thereafter, the gold thin film and the SUS316L material were joined so that the thickness reduction rate of the SUS316L material was 0.5%. Subsequently, the PET film was peeled off, and a 30 nm thick gold thin film was transferred to the surface of the SUS316L material.

なお、本発明の接合装置の模式図を図8に示した。図中、符号9はイオンエッチング装置である。金属基材4および/または貴金属薄膜2がこのイオンエッチング装置9を通過する際に表面活性化処理が施され、圧延機8で接合され、リコイラー5に巻き取られる。   In addition, the schematic diagram of the joining apparatus of this invention was shown in FIG. In the figure, reference numeral 9 denotes an ion etching apparatus. When the metal substrate 4 and / or the noble metal thin film 2 passes through the ion etching device 9, the surface activation treatment is performed, the metal substrate 4 and / or the noble metal thin film 2 are joined by the rolling mill 8 and wound around the recoiler 5.

上記金属薄膜を形成したSUS316L材について、耐食性試験、密着性試験、接触電気抵抗試験を行った。なお、各試験はそれぞれ下記の条件下で行った。   The SUS316L material on which the metal thin film was formed was subjected to a corrosion resistance test, an adhesion test, and a contact electrical resistance test. Each test was performed under the following conditions.

(耐食性試験)
0.1重量%の硫酸液(pH2)0.4リットルを還流しながら沸騰させた雰囲気中に、50×50mmの試験片を168時間保持し、溶液中に溶出した金属イオンを原子吸光光度法で分析し、溶液1リットル当たりの総重量で表した。その結果、溶出量は、0.21mg/lであった。
(Corrosion resistance test)
A test piece of 50 × 50 mm was held for 168 hours in an atmosphere boiled while refluxing 0.4 liter of 0.1 wt% sulfuric acid solution (pH 2), and the metal ions eluted in the solution were analyzed by atomic absorption spectrophotometry. And expressed as the total weight per liter of solution. As a result, the elution amount was 0.21 mg / l.

(密着性試験)
上記耐食性試験を実施した直後の試験片を用い、この試験片の表面を超純水で洗浄後にアセトン置換して乾燥させ、乾いた試験片の金薄膜の表面に幅18mm、長さ50mmの粘着テープを貼り付け、ヘラで良く擦って接着させた後、粘着テープの一端を少し引き上げ、金膜の表面に対してほぼ平行になるようにして一気に素早く引き剥がした。その結果、粘着テープへの金の付着は全くなかった。
(Adhesion test)
Using the test piece immediately after carrying out the corrosion resistance test, the surface of this test piece was washed with ultrapure water and then substituted with acetone and dried. The dry test piece was adhered to the surface of the gold thin film with a width of 18 mm and a length of 50 mm. After affixing the tape and rubbing it well with a spatula, the one end of the adhesive tape was pulled up a little, and it was quickly pulled off at a stretch so that it was almost parallel to the surface of the gold film. As a result, there was no gold adhesion on the adhesive tape.

(接触電気抵抗試験)
50×50mmの試験片の両面を市販のカーボンペーパーで挟み、荷重15kgf/cm、印加電流20Aを貫通通電したときの電圧を測定して、接触電気抵抗を算出した。その結果、3.1mΩcmであった。
(Contact electrical resistance test)
The both sides of a 50 × 50 mm test piece were sandwiched between commercially available carbon papers, and the voltage when a load of 15 kgf / cm 2 and an applied current of 20 A was passed through was measured to calculate the contact electrical resistance. As a result, it was 3.1 mΩcm 2 .

さらに、上記金薄膜を形成したSUS316L材に対し、固体高分子型燃料電池セパレータを作製するためのプレス成形加工を実施したところ、割れを生じることなく成形加工が可能であった。なお、成形加工後に金薄膜の剥離は認められず、耐食性ならびに接触電気抵抗は変化しなかった。   Furthermore, when a press forming process for producing a polymer electrolyte fuel cell separator was performed on the SUS316L material on which the gold thin film was formed, the forming process was possible without causing cracks. In addition, peeling of the gold thin film was not recognized after the forming process, and the corrosion resistance and the contact electric resistance were not changed.

[実施例2]
貴金属担持シートとして、30μm厚のステンレス(SUS304)鋼箔を用い、100nm厚の金メッキを施した後、金メッキ層厚が30nmになるよう、ステンレス鋼箔を圧延した。一方、金属基材として、0.2mm厚の工業用純チタンを用い、真空中(真空度:5×10−4Pa)で高周波プラズマエッチングを行った。その後直ちに、純チタン材の厚さ減少率が1%となるように上記ステンレス鋼箔上の30nm厚の金薄膜と純チタン材を接合した。ステンレス鋼箔を塩化第二鉄によるエッチングで除去することにより、純チタン材の表面に30nm厚の金薄膜を形成した。
[Example 2]
A stainless steel (SUS304) steel foil having a thickness of 30 μm was used as a noble metal carrying sheet, and after gold plating with a thickness of 100 nm was applied, the stainless steel foil was rolled so that the gold plating layer thickness was 30 nm. On the other hand, high-frequency plasma etching was performed in a vacuum (degree of vacuum: 5 × 10 −4 Pa) using 0.2 mm thick industrial pure titanium as a metal substrate. Immediately thereafter, the 30 nm thick gold thin film on the stainless steel foil and the pure titanium material were joined so that the thickness reduction rate of the pure titanium material was 1%. The stainless steel foil was removed by etching with ferric chloride to form a 30 nm thick gold thin film on the surface of the pure titanium material.

上記金薄膜を形成した純チタン材について、前述の条件下で耐食性試験、密着性試験、接触電気抵抗試験を行った結果、耐食性試験:0.01mg/l以下、密着性試験:合格、接触電気抵抗試験:3.3mΩcmの成績を得た。 The pure titanium material on which the gold thin film was formed was subjected to a corrosion resistance test, an adhesion test, and a contact electrical resistance test under the conditions described above. As a result, the corrosion resistance test: 0.01 mg / l or less, the adhesion test: passed, contact electricity Resistance test: A result of 3.3 mΩcm 2 was obtained.

さらに、上記金薄膜付きチタン材に対し、固体高分子型燃料電池用金属セパレータを作製するためのプレス成形加工を実施したところ、割れを生じることなく成形加工が可能であった。なお、成形加工後に金薄膜の剥離は認められず、耐食性ならびに接触電気抵抗は変化しなかった。   Furthermore, when a press molding process for producing a metal separator for a polymer electrolyte fuel cell was performed on the titanium material with a gold thin film, the molding process was possible without causing cracks. In addition, peeling of the gold thin film was not recognized after the forming process, and the corrosion resistance and the contact electric resistance were not changed.

[比較例]
特開2002−254180、特開2002−260681の記載にしたがい、SUS316L材上に100nmの金メッキを施した後、金薄膜が30nmになるように、上記金薄膜付きSUS316L材を圧延した。
[Comparative example]
In accordance with the description in Japanese Patent Application Laid-Open Nos. 2002-254180 and 2002-260681, after the SUS316L material was plated with 100 nm of gold, the SUS316L material with the gold thin film was rolled so that the gold thin film had a thickness of 30 nm.

上記金薄膜を形成したSUS316L材について、腐食試験ならびに接触抵抗測定を実施したところ、所望の耐食性ならびに低接触抵抗を示した。しかしながら、上記金薄膜付きSUS316L材に対し、固体高分子型燃料電池用金属セパレータを作製するためのプレス成形加工を実施したところ、割れを生じ、成形加工ができなかった。   When the corrosion test and the contact resistance measurement were performed on the SUS316L material on which the gold thin film was formed, the desired corrosion resistance and low contact resistance were exhibited. However, when a press forming process for producing a metal separator for a polymer electrolyte fuel cell was performed on the SUS316L material with a gold thin film, a crack was generated and the forming process could not be performed.

以上説明したように、本発明の固体高分子型燃料電池セパレータの貴金属薄膜の形成方法によれば、耐食性、密着性、接触電気抵抗が改善され、かつ低コストで固体高分子型燃料電池用セパレータを作製することができる。   As described above, according to the method for forming a noble metal thin film of the polymer electrolyte fuel cell separator of the present invention, the corrosion resistance, adhesion, and contact electric resistance are improved, and the polymer polymer fuel cell separator is reduced in cost. Can be produced.

本発明の固体高分子型燃料電池セパレータの一例を示す写真である。It is a photograph which shows an example of the polymer electrolyte fuel cell separator of this invention. 本発明における貴金属薄膜が形成された貴金属担持シートの概念図である。It is a conceptual diagram of the noble metal carrying | support sheet | seat in which the noble metal thin film in this invention was formed. 本発明における貴金属薄膜と貴金属担持シートの間に剥離層を設けた例の概念図である。It is a conceptual diagram of the example which provided the peeling layer between the noble metal thin film and the noble metal carrying | support sheet | seat in this invention. 本発明における貴金属薄膜が形成された貴金属担持シートの圧延工程を示す概念図である。It is a conceptual diagram which shows the rolling process of the noble metal carrying | support sheet | seat in which the noble metal thin film in this invention was formed. 本発明における貴金属薄膜が形成された貴金属担持シートと金属基材との圧着工程の一例を示す概念図である。It is a conceptual diagram which shows an example of the crimping | compression-bonding process of the noble metal carrying sheet in which the noble metal thin film in this invention was formed, and a metal base material. 本発明における圧着工程後のエッチングによる貴金属担持シート除去工程を示す概念図である。It is a conceptual diagram which shows the noble metal carrying | support sheet removal process by the etching after the crimping | compression-bonding process in this invention. 本発明における圧着工程後の剥離による貴金属担持シート除去工程を示す概念図である。It is a conceptual diagram which shows the noble metal carrying | support sheet | seat removal process by peeling after the crimping | compression-bonding process in this invention. 本発明の接合装置を示す模式図である。It is a schematic diagram which shows the joining apparatus of this invention.

符号の説明Explanation of symbols

1 貴金属担持シート
2 貴金属薄膜
3 剥離層
4 金属基材
5 リコイラー
6 貴金属担持シートアンコイラー
7 金属基材アンコイラー
8 圧延機
9 イオンエッチング装置
DESCRIPTION OF SYMBOLS 1 Noble metal carrying sheet 2 Noble metal thin film 3 Release layer 4 Metal substrate 5 Recoiler 6 Noble metal carrying sheet uncoiler 7 Metal substrate uncoiler 8 Rolling mill 9 Ion etching apparatus

Claims (3)

貴金属担持シートの一方の表面に貴金属薄膜を形成し、表面が活性化処理された耐食性金属基材に上記貴金属担持シートの貴金属薄膜側を接触させて圧着し、続いて上記貴金属担持シートのみを貴金属薄膜から除去して上記貴金属薄膜を上記耐食性金属基材に転写する固体高分子型燃料電池セパレータの貴金属薄膜形成方法であって、
上記圧着を圧延にて行ない、この圧延による上記金属基材の厚さの減少率が10%未満であることを特徴とする固体高分子型燃料電池セパレータの貴金属薄膜形成方法。
A noble metal thin film is formed on one surface of the noble metal carrying sheet, the noble metal thin film side of the noble metal carrying sheet is brought into contact with a corrosion-resistant metal substrate whose surface has been activated, and then the noble metal carrying sheet alone is precious metal. A method for forming a noble metal thin film of a polymer electrolyte fuel cell separator, wherein the noble metal thin film is removed from a thin film and transferred to the corrosion-resistant metal substrate.
A method for forming a noble metal thin film for a polymer electrolyte fuel cell separator, wherein the pressure bonding is performed by rolling, and a reduction rate of the thickness of the metal substrate by the rolling is less than 10%.
前記貴金属薄膜と前記貴金属担持シートの間に剥離層を設けたことを特徴とする請求項1に記載の固体高分子型燃料電池セパレータの貴金属薄膜形成方法。   The method for forming a noble metal thin film for a polymer electrolyte fuel cell separator according to claim 1, wherein a release layer is provided between the noble metal thin film and the noble metal carrying sheet. 前記活性化処理は、スパッタエッチングであることを特徴とする請求項1または2に記載の固体高分子型燃料電池セパレータの貴金属薄膜形成方法。
3. The method for forming a noble metal thin film for a polymer electrolyte fuel cell separator according to claim 1, wherein the activation treatment is sputter etching.
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JP2002237311A (en) * 2001-02-07 2002-08-23 Sinto Brator Co Ltd Manufacturing method of low contact resistance metal separator for fuel cell
JP2002373673A (en) * 2001-06-15 2002-12-26 Toyo Kohan Co Ltd Separator for fuel cell, manufacturing method of the same, and fuel cell using the fuel cell separator
JP2003105523A (en) * 2001-09-27 2003-04-09 Daido Steel Co Ltd Method of manufacturing corrosion resistant metallic member and corrosion resistant metallic member
JP2003346825A (en) * 2002-05-24 2003-12-05 Seiko Epson Corp Separator for fuel cell, fuel cell assembly having the same, and method for manufacturing separator for fuel cell

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002237311A (en) * 2001-02-07 2002-08-23 Sinto Brator Co Ltd Manufacturing method of low contact resistance metal separator for fuel cell
JP2002373673A (en) * 2001-06-15 2002-12-26 Toyo Kohan Co Ltd Separator for fuel cell, manufacturing method of the same, and fuel cell using the fuel cell separator
JP2003105523A (en) * 2001-09-27 2003-04-09 Daido Steel Co Ltd Method of manufacturing corrosion resistant metallic member and corrosion resistant metallic member
JP2003346825A (en) * 2002-05-24 2003-12-05 Seiko Epson Corp Separator for fuel cell, fuel cell assembly having the same, and method for manufacturing separator for fuel cell

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