# US 2014/0193668 A1 · Stainless steel for fuel cell separator

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- Number: US 2014/0193668 A1
- Document ID: US20140193668A1
- Status: Published application
- Kind: A1
- Application number: 14/235,927
- Filed: 2012-07-25
- Published: 2014-07-10
- Earliest claimed: 2011-07-29
- Assignees: Jfe Steel Corporation
- Inventors: Noriko Makiishi; Hisato Noro; Shin Ishikawa; Shinsuke Ide; Tomohiro Ishii; Masayasu Nagoshi
- Web page: https://patentgrep.com/patent/US20140193668A1

## CPC

- H01M 8/021: Alloys based on iron
- C21D 6/004: {containing Cr and Ni}
- C21D 9/46: for sheet metals
- C22C 38/001: {containing N}
- C22C 38/004: {Very low carbon steels, i.e. having a carbon content of less than 0,01%}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/22: with molybdenum or tungsten
- C22C 38/26: with niobium or tantalum
- C22C 38/28: with titanium or zirconium
- C22C 38/40: with nickel
- C23G 1/086: {solutions containing HF}
- C25F 1/00: Electrolytic cleaning, degreasing, pickling or descaling
- Y02E 60/50: Fuel cells
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- Y10T 428/12993: Surface feature [e.g., rough, mirror]
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C25F: PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Stainless steel for fuel cell separators are provided which exhibit stable contact resistance characteristics and excellent practical utility. The stainless steel contains not less than 16 mass % of Cr. When the surface configuration of the stainless steel is analyzed with a scanning electron microscope at a spatial resolution of not more than 0.1 μm, the surface modulus is not less than 1.02. Preferably, the chemical composition further includes C: not more than 0.03%, Si: not more than 1.0%, Mn: not more than 1.0%, S: not more than 0.01%, P: not more than 0.05%, Al: not more than 0.20%, N: not more than 0.03%, Cr: 16 to 40%, and one or more of Ni: not more than 20%, Cu: not more than 0.6% and Mo: not more than 2.5%, the balance being Fe and inevitable impurities.

## Claims

### Claim 1

A stainless steel for fuel cell separators, wherein the stainless steel contains not less than 16 mass % of Cr and has a surface modulus of not less than 1.02, the surface modulus being obtained by a measurement of surface configuration with respect to the surface of the stainless steel with a scanning electron microscope at a spatial resolution of not more than 0.1 μm.

### Claim 2 (depends on 1)

The stainless steel for fuel cell separators according to claim 1, wherein the surface modulus is not less than 1.04.

### Claim 3 (depends on 1)

The stainless steel for fuel cell separators according to claim 1, wherein the stainless steel further contains, by mass, C: not more than 0.03%, Si: not more than 1.0%, Mn: not more than 1.0%, S: not more than 0.01%, P: not more than 0.05%, Al: not more than 0.20%, N: not more than 0.03%, Cr: 16 to 40%, and one or more of Ni: not more than 20%, Cu: not more than 0.6% and Mo: not more than 2.5%, the balance being Fe and inevitable impurities.

### Claim 4 (depends on 1)

The stainless steel for fuel cell separators according to claim 1, wherein the stainless steel further contains not more than 1.0% by mass of a total of one or more of Nb, Ti and Zr.

### Claim 5 (depends on 2)

The stainless steel for fuel cell separators according to claim 2, wherein the stainless steel further contains not more than 1.0% by mass of a total of one or more of Nb, Ti and Zr.

### Claim 6 (depends on 3)

The stainless steel for fuel cell separators according to claim 3, wherein the stainless steel further contains not more than 1.0% by mass of a total of one or more of Nb, Ti and Zr.

### Claim 7 (depends on 2)

The stainless steel for fuel cell separators according to claim 2, wherein the stainless steel further contains, by mass, C: not more than 0.03%, Si: not more than 1.0%, Mn: not more than 1.0%, S: not more than 0.01%, P: not more than 0.05%, Al: not more than 0.20%, N: not more than 0.03%, Cr: 16 to 40%, and one or more of Ni: not more than 20%, Cu: not more than 0.6% and Mo: not more than 2.5%, the balance being Fe and inevitable impurities.