# US 2014/0154129 A1 · Stainless steel for fuel cell separator

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- Number: US 2014/0154129 A1
- Document ID: US20140154129A1
- Status: Published application
- Kind: A1
- Application number: 14/131,030
- Filed: 2012-07-25
- Published: 2014-06-05
- 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/US20140154129A1

## CPC

- H01M 8/021: Alloys based on iron
- C21D 6/004: {containing Cr and Ni}
- C21D 9/00: Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- 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 38/20: with copper
- 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
- 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

## Abstract

Stainless steel for fuel cell separators contains C: ≦0.03%, Si: ≦1.0%, Mn: ≦1.0%, S: ≦0.01%, P: ≦0.05%, Al: ≦0.20%, N: ≦0.03%, Cr: 16 to 40%, and one or more of Ni: ≦20%, Cu: ≦0.6% and Mo: ≦2.5%, the balance being Fe and inevitable impurities. According to X-ray photoelectron spectroscopy, the surface of the stainless steel contains fluorine and provides a 3.0 or higher ratio of the total of atomic concentrations of Cr and Fe in other than the metallic forms calculated from data resulting from the separation of peaks of Cr and Fe into metallic peaks and peaks other than the metallic peaks to the total of atomic concentrations of Cr and Fe in the metallic forms calculated from data resulting from the separation of peaks of Cr and Fe into metallic peaks and peaks other than the metallic peaks.

## Claims

### Claim 1

A stainless steel for fuel cell separators wherein the stainless steel 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, and
wherein according to X-ray photoelectron spectroscopy, the surface of the stainless steel contains fluorine and satisfies the following relation:
(Cr+Fe) in other than metallic forms/(Cr+Fe) in metallic forms≧3.0
wherein (Cr+Fe) in other than metallic forms indicates the total of atomic concentrations of Cr and Fe in other than the metallic forms calculated from data resulting from the separation of peaks of Cr and Fe into metallic peaks and peaks other than the metallic peaks, and (Cr+Fe) in metallic forms indicates the total of atomic concentrations of Cr and Fe in the metallic forms calculated from the data resulting from the separation of the peaks of Cr and Fe into metallic peaks and peaks other than the metallic peaks.

### Claim 2 (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.