JP3433435B2 - Stainless steel with excellent resistance to molten carbonate corrosion - Google Patents

Stainless steel with excellent resistance to molten carbonate corrosion

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Publication number
JP3433435B2
JP3433435B2 JP30529494A JP30529494A JP3433435B2 JP 3433435 B2 JP3433435 B2 JP 3433435B2 JP 30529494 A JP30529494 A JP 30529494A JP 30529494 A JP30529494 A JP 30529494A JP 3433435 B2 JP3433435 B2 JP 3433435B2
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JP
Japan
Prior art keywords
molten carbonate
corrosion
stainless steel
corrosion resistance
scale
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP30529494A
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Japanese (ja)
Other versions
JPH08165546A (en
Inventor
佳孝 西山
芳男 樽谷
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Sumitomo Metal Industries Ltd
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Priority to JP30529494A priority Critical patent/JP3433435B2/en
Publication of JPH08165546A publication Critical patent/JPH08165546A/en
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0206—Metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/14—Fuel cells with fused electrolytes
    • H01M2008/147—Fuel cells with molten carbonates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0048—Molten electrolytes used at high temperature
    • H01M2300/0051—Carbonates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0206—Metals or alloys
    • H01M8/0208—Alloys
    • H01M8/021—Alloys based on iron
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、溶融炭酸塩型燃料電池
に用いられる耐溶融炭酸塩腐食性に優れたステンレス鋼
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to stainless steel having excellent resistance to molten carbonate corrosion, which is used in molten carbonate fuel cells.

【０００２】[0002]

【従来の技術】２１世紀における石油資源枯渇問題や大
気汚染を含めた環境問題に対処するために、次世代の電
力供給源として石炭改質ガスが利用できる燃料電池が脚
光を浴び始めている。燃料電池は起電力を発生する電解
質によってリン酸型、溶融炭酸塩型、固体電解質型など
の種類があり、各々運転温度、発電効率が異なる。この
うち、ＬＮＧや石炭改質ガスを利用する溶融炭酸塩型燃
料電池は分散型電源やガスタービンとの複合発電による
大規模集中型電源として注目されている。現在１００ｋ
Ｗ級スタックの開発が終了し、１ＭＷ級プラントの開発
が着手されている。しかしながら、このような大型化を
実現し、商用プラントとして実用化されるためには装置
の長時間の安定性と信頼性、さらには低コスト化が重要
となる。現状での大きな問題のひとつとして、電解質と
して使用されるLi2CO3やK2CO3 等を混合した溶融炭酸塩
による金属材料の腐食がある。特に、600 〜700 ℃の高
温の溶融炭酸塩に接するセパレータ材や集電板はカソー
ド側において激しい腐食にさらされ、電池の劣化要因と
なっている。2. Description of the Related Art Fuel cells, which can use coal reformed gas as a power source for the next generation, have begun to be in the limelight in order to deal with environmental problems including oil resource depletion and air pollution in the 21st century. There are various types of fuel cells, such as phosphoric acid type, molten carbonate type, and solid electrolyte type, depending on the electrolyte that generates electromotive force, and the operating temperature and power generation efficiency are different. Among them, a molten carbonate fuel cell using LNG or coal reformed gas is drawing attention as a distributed power source or a large-scale centralized power source by combined power generation with a gas turbine. 100k now
The development of the W-class stack has been completed, and the development of the 1MW-class plant is underway. However, in order to realize such an increase in size and put it into practical use as a commercial plant, long-term stability and reliability of the apparatus and further cost reduction are important. One of the major problems at present is the corrosion of metallic materials by molten carbonate mixed with Li 2 CO 3 or K 2 CO 3 used as an electrolyte. In particular, the separator material and collector plate that come into contact with the molten carbonate at a high temperature of 600 to 700 ° C. are exposed to severe corrosion on the cathode side, which is a cause of battery deterioration.

【０００３】現在、セパレータ材としては、ＪＩＳ規格
SUS316L やSUS310S が用いられているが、耐食性は十分
ではない。Fe-Cr-Ni系ステンレス鋼の溶融炭酸塩に対す
る耐食性の改善策としては、特公平4-37154 号公報では
1 〜2 ％のAl添加が、特開昭63-190143 号公報では0.1
〜0.9 ％のAlと0.5 ％以下のＹの複合添加が、また特開
平1-252750号公報および特開平1-252757号公報ではSi量
を0.2 ％以下に制御し、かつAlを0.05〜2 ％添加するこ
とが開示されている。また、特開平4-247852号公報では
Crを5 〜26％、Niを0.5 〜19％、Mnを0.2 〜35％に規定
することにより耐食性が改善されるとしている。しかし
ながら、これらはSUS316L 等の従来材に比較し、耐食性
の向上が見られるというものであり、長期間の耐用を考
えた場合、溶融炭酸塩に対する耐食性はまだ十分ではな
いという問題がある。Currently, as a separator material, the JIS standard is used.
Although SUS316L and SUS310S are used, their corrosion resistance is not sufficient. Japanese Patent Publication No. 4-37154 discloses a method for improving the corrosion resistance of Fe-Cr-Ni stainless steel against molten carbonate.
The addition of 1 to 2% of Al is 0.1% in JP-A-63-190143.
.About.0.9% Al and 0.5% or less Y added in combination, and in JP-A 1-252750 and 1-252757, the Si content was controlled to 0.2% or less, and Al was 0.05-2%. Addition is disclosed. Further, in Japanese Patent Laid-Open No. 4-247852,
It is said that the corrosion resistance is improved by specifying Cr to 5 to 26%, Ni to 0.5 to 19%, and Mn to 0.2 to 35%. However, compared with conventional materials such as SUS316L, these have improved corrosion resistance, and when considering long-term service, there is a problem that the corrosion resistance to molten carbonate is still insufficient.

【０００４】[0004]

【発明が解決しようとする課題】このように溶融炭酸塩
型燃料電池に使用される金属材料については、溶融炭酸
塩中での腐食機構が十分に解明されていないこともあ
り、決定的な耐食性材料は開発されていないのが現状で
ある。As described above, with respect to the metal material used in the molten carbonate fuel cell, the corrosion mechanism in the molten carbonate has not been sufficiently clarified. At present, the material has not been developed.

【０００５】本発明の目的は、溶融炭酸塩型燃料電池の
構造部材に使用できる金属材料として、特にカソード側
環境においても優れた耐食性をもつステンレス鋼を提供
することにある。An object of the present invention is to provide, as a metal material that can be used for a structural member of a molten carbonate fuel cell, stainless steel having excellent corrosion resistance even in an environment on the cathode side.

【０００６】[0006]

【課題を解決するための手段】本発明者らは、溶融炭酸
塩型燃料電池において、特にカソード側環境において優
れた耐食性をもつFe−Cr−Ni系ステンレス鋼の材料開発
をめざし、広範囲に化学組成を変えた材料について、生
成するスケールの組成、構造に着目し、系統的な調査、
研究を重ねた。その結果、以下のような知見を得るに至
った。[Means for Solving the Problems] In the molten carbonate fuel cell, the inventors of the present invention aim to develop a material of Fe--Cr--Ni system stainless steel having excellent corrosion resistance particularly in the cathode side environment, and have a wide range of chemical properties. For materials with different compositions, focusing on the composition and structure of the generated scale, systematic investigation,
Repeated research. As a result, the following findings have been obtained.

【０００７】Ａ）材料表面に生成するスケールが、Cr系
主体の酸化物の場合は、容易に電解質であるLi2CO3と反
応し、LiCrO2を形成するため耐食性が劣るばかりか電解
質の損失を招くこと。A) When the scale formed on the surface of the material is an oxide mainly composed of Cr, it easily reacts with Li 2 CO 3 which is an electrolyte to form LiCrO 2 , so that not only the corrosion resistance is deteriorated but also the loss of the electrolyte. To invite.

【０００８】Ｂ）Cr系酸化物を生成する合金にTiを適正
量添加することにより、Cr系酸化物の外側にFe系酸化物
とTi系酸化物から成る外層スケールが、内側にTi系内部
酸化層が形成される。この外層スケールは溶融炭酸塩に
対する溶解度が小さく、溶融炭酸塩腐食に優れた耐食性
を示すこと。B) By adding an appropriate amount of Ti to an alloy that produces a Cr-based oxide, an outer layer scale composed of a Fe-based oxide and a Ti-based oxide is provided outside the Cr-based oxide, and a Ti-based interior is provided inside. An oxide layer is formed. This outer scale has a low solubility in molten carbonate and shows excellent corrosion resistance against molten carbonate corrosion.

【０００９】Ｃ）上記のTi系内部酸化層はCr系酸化物内
の合金との界面に形成されており、スケールの密着性を
向上させ、耐食性の安定に有効であること。C) The above Ti-based internal oxide layer is formed at the interface with the alloy in the Cr-based oxide and is effective for improving the adhesion of scale and stabilizing the corrosion resistance.

【００１０】Ｄ）外層スケール中のTi系酸化物が増え、
スケールの最外表面を被うTi系酸化物が増えると、溶融
炭酸塩の浸延性が抑制されること。ここに浸延性とは、
溶融炭酸塩が合金表面に付着した時、その溶融炭酸塩が
表面を浸食しつつ周辺域に広がる性質を言う。D) The Ti-based oxide in the outer scale increases,
When the Ti-based oxide covering the outermost surface of the scale increases, the ductility of molten carbonate is suppressed. Here, the ductility is
When molten carbonate adheres to the alloy surface, the molten carbonate erodes the surface and spreads to the peripheral area.

【００１１】Ｅ）前記Ｂ）の二層スケールの形成は、Ti
に加えさらにＹ、Ca、希土類元素及びAlのうちの一種以
上を適正量添加することにより促進され、かつそのスケ
ールは長時間にわたり安定であること。E) The formation of the two-layer scale in the above B) is performed by using Ti
In addition, it is promoted by adding an appropriate amount of one or more of Y, Ca, rare earth elements and Al, and the scale is stable for a long time.

【００１２】本発明は、これらの知見に基づき完成させ
たものであり、その要旨は、「重量％で、Ｃ：0.15％
以下、Si：0.3 〜2 ％、Mn：2 ％以下、Cr：15〜30％、
Ni：7 〜35％、Ti：0.2 〜5 ％で、残部がFeおよび不可
避的不純物からなることを特徴とする耐溶融炭酸塩腐食
性に優れたステンレス鋼、または重量％で、Ｃ：0.15
％以下、Si：0.3 〜2 ％、Mn：2 ％以下、Cr：15〜30
％、Ni：7 〜35％、Ti：0.2 〜5 ％で、さらに各々0.01
〜1 ％のＹ、Caおよび希土類元素ならびに0.1 〜0.89％
のAlからなる群から選んだ１種以上を含み、残部がFeお
よび不可避的不純物からなることを特徴とする耐溶融炭
酸塩腐食性に優れたステンレス鋼」にある。The present invention has been completed based on these findings, and the gist thereof is "% by weight, C: 0.15%
Below, Si: 0.3-2%, Mn: 2% or less, Cr: 15-30%,
Ni: 7 to 35%, Ti: 0.2 to 5%, the balance being Fe and inevitable impurities, the stainless steel having excellent resistance to molten carbonate corrosion, or C: 0.15% by weight.
% Or less, Si: 0.3 to 2%, Mn: 2% or less, Cr: 15 to 30
%, Ni: 7 to 35%, Ti: 0.2 to 5%, and 0.01 each
~ 1% Y, Ca and rare earth elements and 0.1 ~ 0.89 %
Of stainless steel, which is characterized by containing at least one selected from the group consisting of Al, with the balance being Fe and inevitable impurities, and having excellent resistance to molten carbonate corrosion ”.

【００１３】[0013]

【作用】以下に本発明のステンレス鋼における各成分の
作用効果と含有量の限定理由について述べる。The function and effect of each component in the stainless steel of the present invention and the reasons for limiting the content will be described below.

【００１４】Ｃ：Ｃはオーステナイト組織の安定化を促
進するとともに高温強度を高めるのに有効な元素である
ので含有量は0.01％以上とすることが望ましいが、0.15
％を超えると熱間加工性を阻害するので0.15％以下に限
定する。C: C is an element effective for promoting the stabilization of the austenite structure and enhancing the high temperature strength, so the content is preferably 0.01% or more.
%, The hot workability is impaired, so the content is limited to 0.15% or less.

【００１５】Si：Siは鋼の溶製時の脱酸剤として添加さ
れるものである。さらに、Siは溶融炭酸塩腐食環境にお
いては、生成されるスケールの合金との界面にSi系内部
酸化物を形成し、スケールの密着性を高め耐食性を向上
させる。このため、Siは0.3％以上含有させることが必
要であるが、含有量の増加とともに加工性、溶接性の低
下が著しくなるため上限は2 ％とする。Si: Si is added as a deoxidizer during the melting of steel. Furthermore, Si forms a Si-based internal oxide at the interface with the alloy of the scale to be produced in a molten carbonate corrosive environment, increasing the adhesion of the scale and improving the corrosion resistance. For this reason, it is necessary to contain Si in an amount of 0.3% or more. However, the workability and weldability decrease significantly as the content increases, so the upper limit is 2%.

【００１６】Mn：MnはSiと同様、溶製時の脱酸剤として
添加されるものである。また、オーステナイト組織の安
定化に有効であるので0.1%以上含有させることが望まし
いが、多量の添加は耐酸化性を劣化させるので上限を2
％とする。Mn: Mn, like Si, is added as a deoxidizing agent during melting. Further, it is desirable to contain 0.1% or more because it is effective in stabilizing the austenite structure, but addition of a large amount deteriorates the oxidation resistance, so the upper limit is 2%.
%.

【００１７】Cr：Crはカソード側環境において、耐溶融
炭酸塩腐食性を向上させる作用があり、その効果は15％
以上で発揮される。しかしながら、Cr含有量が増える
と、生成スケールがCr系主体の単一酸化スケールとな
り、電解質であるLi2CO3と反応し、LiCrO2を形成し、電
解質中に溶出しやすく、皮膜の安定性を劣下させ、また
電解質の損失を招くことから、Crは30％以下に制限す
る。Cr: Cr has the effect of improving the molten carbonate corrosion resistance in the cathode side environment, and its effect is 15%.
It is demonstrated above. However, when the Cr content increases, the generated scale becomes a single oxide scale mainly composed of Cr and reacts with Li 2 CO 3 which is the electrolyte to form LiCrO 2, which easily elutes in the electrolyte and the stability of the film Is deteriorated and the loss of the electrolyte is caused, so Cr is limited to 30% or less.

【００１８】Ni ：Niはオーステナイト組織の安定化及
び耐酸化性とクリープ強度の向上のため必要な元素であ
るが、7 ％未満ではその効果が小さく、他方Ni含有量が
35％を超えると熱間加工性を阻害するのでその範囲を7
％以上、35％以下とする。Ni: Ni is an element necessary for stabilizing the austenite structure and improving the oxidation resistance and creep strength, but if it is less than 7%, its effect is small, while the Ni content is
If it exceeds 35%, hot workability is impaired, so the range is set to 7
% Or more and 35% or less.

【００１９】Ti ：Tiは本発明鋼において最も重要な元
素のひとつである。Tiを0.2 ％以上含有させると生成ス
ケールの外層側にTi系酸化物が生成され、Fe系酸化物
（Fe3O4あるいはLiFeO2）とともに混在する。これらTi
及びFe系酸化物は溶融炭酸塩中への溶解度が小さく合金
の耐食性を向上させる。また0.2 ％以上のTiの含有によ
り、生成スケール内層側のCr系酸化物の合金界面にTi系
内部酸化層が形成される。このTi系内部酸化層は、スケ
ールの密着性を向上させ、耐食性を安定させる作用をも
つ。さらに、Ti含有量を増加させると二層スケール外層
のTi系酸化物の量が増え、Ti含有量が約0.7 ％を超える
と溶融炭酸塩の合金表面への浸延を阻止する効果が顕著
となり、腐食を抑えるとともに電解質である溶融炭酸塩
の損失を抑制する。しかしながらTiの含有量が5 ％を超
えると加工性、靭性の低下が著しくなる。したがって、
Tiの適正な含有量は0.2 〜5 ％の範囲であるが、さらに
安定した耐食性のためには1 ％を超えて5 ％までの範囲
とすることが好ましい。Ti: Ti is one of the most important elements in the steel of the present invention. When Ti is contained in an amount of 0.2% or more, Ti-based oxide is generated on the outer layer side of the generated scale and is mixed with Fe-based oxide (Fe 3 O 4 or LiFeO 2 ). These Ti
And Fe-based oxides have low solubility in molten carbonate and improve the corrosion resistance of alloys. Further, if the content of Ti is 0.2% or more, a Ti-based internal oxide layer is formed at the alloy interface of the Cr-based oxide on the inner layer side of the produced scale. This Ti-based internal oxide layer has the function of improving the adhesion of the scale and stabilizing the corrosion resistance. Furthermore, when the Ti content is increased, the amount of Ti-based oxide in the outer layer of the double-layer scale increases, and when the Ti content exceeds 0.7%, the effect of preventing the molten carbonate from spreading on the alloy surface becomes remarkable. In addition, it suppresses corrosion and suppresses loss of molten carbonate as an electrolyte. However, if the Ti content exceeds 5%, the workability and toughness are significantly reduced. Therefore,
The proper content of Ti is in the range of 0.2 to 5%, but it is preferably in the range of more than 1% and up to 5% for more stable corrosion resistance.

【００２０】以上のように化学組成を制限することで溶
融炭酸塩中で優れた耐食性を有するステンレス鋼を得る
ことができるが、さらに下記に示す元素の少なくとも１
種以上を適正量含有させることによりその効果を一層高
めることができる。以下に各元素の作用効果と含有量の
限定理由について述べる。By limiting the chemical composition as described above, a stainless steel having excellent corrosion resistance in molten carbonate can be obtained, and at least one of the elements shown below is also used.
The effect can be further enhanced by containing an appropriate amount of at least one species. The effect of each element and the reasons for limiting the content are described below.

【００２１】Ｙ、Ca、希土類元素、Al：これらの元素
は、Cr系酸化物の外側へのTi系酸化物とFe系酸化物から
成る外層スケールの形成を促進するとともに、腐食進行
後の金属イオンの外方拡散および酸素イオンの内方拡散
を抑制するため耐溶融炭酸塩腐食性の向上に有効な元素
である。しかしながら、Ｙ、Ca、希土類元素は、各々0.
01％未満ではその効果を発揮し得ず、1.0 ％を超える含
有は熱間加工性及び溶接性を阻害するのでその範囲を0.
01〜1 ％とする。Alの含有量は0.1 ％以下ではその効果
が得られず、一方、多量の含有は耐食性の向上には寄与
するものの、スケール中に生成されるAl系酸化物は絶縁
酸化物であるため電気伝導性が小さく、電池性能を劣化
させる。従って、Al含有量の上限を0.89％とする。ま
た、Ｙ、Ca、希土類元素は、0.01〜1％の含有で生成ス
ケールと合金との密着性を高めスケールの剥離を抑制す
る効果がある。Y, Ca, rare earth elements, Al: These elements promote the formation of the outer layer scale composed of the Ti-based oxide and the Fe-based oxide on the outside of the Cr-based oxide, and at the same time, the metal after the corrosion progresses. It is an element effective for improving molten carbonate corrosion resistance because it suppresses outward diffusion of ions and inward diffusion of oxygen ions. However, Y, Ca, and rare earth elements are each 0.
If the content is less than 01%, the effect cannot be exhibited, and if the content exceeds 1.0%, the hot workability and weldability are impaired.
01 to 1% If the Al content is 0.1% or less, the effect cannot be obtained. On the other hand, although a large amount of Al contributes to the improvement of corrosion resistance, the Al-based oxide generated in the scale is an insulating oxide, so it has a high electrical conductivity. Poor in performance, deteriorating battery performance. Therefore, the upper limit of the Al content is 0.89 %. Further, Y, Ca, and rare earth elements, when contained in an amount of 0.01 to 1%, have the effect of increasing the adhesion between the produced scale and the alloy and suppressing scale peeling.

【００２２】[0022]

【実施例】本発明を以下の実施例に基づきさらに具体的
に説明する。EXAMPLES The present invention will be described more specifically based on the following examples.

【００２３】表１に本発明鋼(No.1 〜15) 及び比較鋼(S
US310S、SUS316L 及びNo.16 〜21)の化学組成（重量
％、残部はFe）を示す。これらの試料は、高周波電気炉
で真空溶製した25kg鋼塊を鍛造、熱間圧延し、1150℃で
溶体化処理を行った熱延板より切り出し製作した。試験
片の大きさは、厚さ2 ｍｍ、幅20ｍｍ、長さ80ｍｍであ
る。Table 1 shows the steels of the present invention (Nos. 1 to 15) and comparative steels (S
US310S, SUS316L and No. 16-21) chemical composition (% by weight, balance Fe). These samples were produced by forging a 25 kg steel ingot vacuum-melted in a high-frequency electric furnace, hot-rolling it, and cutting it from a hot-rolled sheet that was solution-treated at 1150 ° C. The size of the test piece is 2 mm in thickness, 20 mm in width, and 80 mm in length.

【００２４】[0024]

【表１】 [Table 1]

【００２５】腐食試験は、炭酸塩としてLi2CO3：K2CO3
＝62：38（モル比）の混合塩を試験片に塗布し、650 ℃
でCO2 ：空気＝30：70（体積比）の雰囲気ガス中にて20
0 時間保持することで行なった。耐食性は試験後脱スケ
ールした試験片の重量を、試験前の重量から差引いた重
量減少量にて評価した。Corrosion tests were conducted using Li 2 CO 3 : K 2 CO 3 as a carbonate.
= 62:38 (molar ratio) of mixed salt was applied to the test piece and 650 ℃
20 in the atmosphere gas of CO 2 : air = 30:70 (volume ratio)
It was held for 0 hours. The corrosion resistance was evaluated by the weight reduction amount obtained by subtracting the weight of the test piece descaled after the test from the weight before the test.

【００２６】また、溶融炭酸塩の浸延性を調べるため、
試験片をワイヤで吊るし、前記の混合塩中に半浸漬の状
態で200 時間保持した。試験温度及び雰囲気は、腐食試
験と同様の条件にて実施した（以下、半浸漬試験と称
す）。溶融炭酸塩の浸延性は、試験後の試験片の気液界
面から未浸漬部へ上昇した塩の状態を目視観察にて評価
し、未浸漬部への塩の上昇が小さいほど浸延性が小さ
く、耐食性に優れると判断した。Further, in order to investigate the ductility of molten carbonate,
The test piece was hung with a wire and held in the above-mentioned mixed salt in a semi-immersed state for 200 hours. The test temperature and atmosphere were the same as those of the corrosion test (hereinafter referred to as the semi-immersion test). The ductility of molten carbonate is evaluated by visually observing the state of the salt that has risen from the gas-liquid interface of the test piece to the non-immersed portion after the test. It was judged that the corrosion resistance was excellent.

【００２７】図１は腐食試験における各試験材の腐食減
量とTi含有量の関係を示したものである。従来材SUS316
L は腐食減量が非常に大きい。Ti含有量が本発明の範囲
外にある比較鋼Ｎｏ.18 ，19はSUS316L に比べると腐食
減量が小さいものの、SUS310S とほぼ同レベルである。
これらに比べ、Tiを0.2 ％以上含有する本発明鋼Ｎｏ.1
〜8 では腐食減量が5mg/cm2 以下と一段と低減してお
り、本発明で定める範囲のTi含有により耐食性が著しく
改善されることがわかる。FIG. 1 shows the relationship between the corrosion weight loss and the Ti content of each test material in the corrosion test. Conventional material SUS316
L has a very large corrosion weight loss. Comparative steel Nos. 18 and 19 having a Ti content outside the range of the present invention have a smaller corrosion weight loss than SUS316L, but are almost at the same level as SUS310S.
Compared to these, steel No. 1 of the present invention containing 0.2% or more of Ti
At ~ 8, the corrosion weight loss is further reduced to 5 mg / cm 2 or less, and it can be seen that the corrosion resistance is remarkably improved by the inclusion of Ti within the range defined by the present invention.

【００２８】表２は本発明鋼及び比較鋼の腐食試験によ
る腐食減量および、半浸漬試験での溶融炭酸塩の未浸漬
部への浸延性を評価した結果である。Table 2 shows the results of evaluating the corrosion weight loss of the steels of the present invention and the comparative steels by the corrosion test, and the dipability of the molten carbonate in the unimmersed part in the semi-immersion test.

【００２９】[0029]

【表２】 [Table 2]

【００３０】本発明で定める範囲のTi含有に加え、さら
にAl、Ｙ、Ca、希土類元素のうち１種または２種以上を
含有する本発明鋼Ｎｏ.9〜13の腐食試験における腐食減
量は、比較鋼Ｎｏ.18 、19より小さいことは勿論、本発
明鋼Ｎｏ.1〜8 に比べても小さく、Tiとこれら元素の複
合含有が溶融炭酸塩中での耐食性の向上に有効であるこ
とがわかる。Corrosion weight loss in the corrosion test of Steel Nos. 9 to 13 of the present invention containing one or more of Al, Y, Ca and rare earth elements in addition to the Ti content in the range defined by the present invention, It is not only smaller than Comparative Steel Nos. 18 and 19 but also smaller than Comparative Steel Nos. 1 to 8, and the combined inclusion of Ti and these elements is effective for improving the corrosion resistance in molten carbonate. Recognize.

【００３１】また、半浸漬試験の結果から、本発明鋼Ｎ
ｏ.1〜8 およびＮｏ.9〜13では、溶融炭酸塩の未浸漬部
への上昇は、いずれの比較鋼よりも少なく、本発明で定
める範囲のTi含有、またはTiとAl、Ｙ、Ca、希土類元素
のうち１種以上の複合含有は、溶融炭酸塩の浸延に対す
る抵抗を高くすることがわかる。溶融炭酸塩の浸延性が
小さいことは、腐食のみならず、電解質の損失をも抑制
することを意味するので、本発明鋼を用いれば電池寿命
の大幅な向上が達成できる。From the results of the semi-immersion test, the steel of the present invention N
In Nos. 1 to 8 and Nos. 9 to 13 , the rise of the molten carbonate to the non-immersed part was less than that of any of the comparative steels, and the Ti content in the range defined by the present invention, or Ti and Al, Y, Ca. It can be seen that the composite inclusion of one or more of the rare earth elements increases the resistance to the infiltration of the molten carbonate. The low ductility of the molten carbonate means that not only corrosion but also loss of the electrolyte is suppressed. Therefore, when the steel of the present invention is used, the battery life can be significantly improved.

【００３２】[0032]

【発明の効果】本発明のステンレス鋼は、耐溶融炭酸塩
腐食性に優れ、かつ、溶融炭酸塩の浸延性に抵抗があり
電解質の損失を抑制する性質がある。したがって、本発
明鋼を溶融炭酸塩型燃料電池の集電板やセパレータ材な
どとして使用した場合、溶融炭酸塩に接する腐食の激し
い部位の耐食性が飛躍的に改善されるとともに、電解質
である溶融炭酸塩の損失が抑えられ電池の寿命を大幅に
向上させることが可能となる。INDUSTRIAL APPLICABILITY The stainless steel of the present invention is excellent in molten carbonate corrosion resistance, resistant to the infiltration of molten carbonate, and has the property of suppressing electrolyte loss. Therefore, when the steel of the present invention is used as a collector plate or a separator material of a molten carbonate fuel cell, the corrosion resistance of a severely corroded portion in contact with molten carbonate is dramatically improved, and molten carbonate as an electrolyte is used. The loss of salt can be suppressed and the battery life can be significantly improved.

【図面の簡単な説明】[Brief description of drawings]

【図１】溶融炭酸塩による腐食減量と鋼中のTi含有量と
の関係を示す図である。FIG. 1 is a diagram showing the relationship between the corrosion weight loss due to molten carbonate and the Ti content in steel.

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平１−252757（ＪＰ，Ａ) 特開 昭59−225805（ＪＰ，Ａ) 特開 平７−188870（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C22C 38/00 - 38/60 H01M 8/02,8/14 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-1-252757 (JP, A) JP-A-59-225805 (JP, A) JP-A-7-188870 (JP, A) (58) Field (Int.Cl. 7 , DB name) C22C 38/00-38/60 H01M 8 / 02,8 / 14

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】重量％で、Ｃ：0.15％以下、Si：0.3 〜2
％、Mn：2 ％以下、Cr：15〜30％、Ni：7 〜35％、Ti：
0.2 〜5 ％で、残部がFeおよび不可避的不純物からなる
ことを特徴とする耐溶融炭酸塩腐食性に優れたステンレ
ス鋼。1. By weight%, C: 0.15% or less, Si: 0.3-2.
%, Mn: 2% or less, Cr: 15 to 30%, Ni: 7 to 35%, Ti:
Stainless steel with excellent resistance to molten carbonate corrosion, characterized by 0.2 to 5% with the balance being Fe and inevitable impurities. 【請求項２】請求項１に記載の成分に加えて、さらに
Ｙ：0.01〜1 ％、Ca：0.01〜1 ％、希土類元素：0.01〜
1 ％、Al：0.1 〜0.89％のうちの１種以上を含み、残部
がFeおよび不可避的不純物からなることを特徴とする耐
溶融炭酸塩腐食性に優れたステンレス鋼。2. In addition to the components according to claim 1, Y: 0.01-1%, Ca: 0.01-1%, rare earth element: 0.01-
1%, Al: 0.1 to 0.89 % of one or more kinds, and the balance consisting of Fe and unavoidable impurities, stainless steel excellent in molten carbonate corrosion resistance.
JP30529494A 1994-12-09 1994-12-09 Stainless steel with excellent resistance to molten carbonate corrosion Expired - Fee Related JP3433435B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP30529494A JP3433435B2 (en) 1994-12-09 1994-12-09 Stainless steel with excellent resistance to molten carbonate corrosion

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Application Number Priority Date Filing Date Title
JP30529494A JP3433435B2 (en) 1994-12-09 1994-12-09 Stainless steel with excellent resistance to molten carbonate corrosion

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JP3433435B2 true JP3433435B2 (en) 2003-08-04

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2352443C (en) * 2000-07-07 2005-12-27 Nippon Steel Corporation Separators for solid polymer fuel cells and method for producing same, and solid polymer fuel cells
KR20030097458A (en) * 2002-06-21 2003-12-31 현대자동차주식회사 Ferrite-based stainless alloy for interconnector of solid oxide fuel cell
CN102251191B (en) * 2011-07-21 2016-03-09 重庆仪表材料研究所 The preparation method of a kind of Martensite Stainless Steel and stainless steel bandlet thereof
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