Stainless steel sheet for fuel cell separators and production method therefor

Patent metadata

Field	Value
Publication number	US-11085120-B2
Application number	US-201816489881-A
Country	US
Kind code	B2
Filing date	Apr 2, 2018
Priority date	Apr 25, 2017
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

A stainless steel sheet for fuel cell separators comprises a predetermined chemical composition, wherein the stainless steel sheet has a textured structure at a surface thereof, an average interval between projected parts of the textured structure being 20 nm or more and 200 nm or less, and a ratio [Cr]/[Fe] of an atomic concentration of Cr existing in chemical form other than metal to an atomic concentration of Fe existing in chemical form other than metal at the surface of the stainless steel sheet is 2.0 or more.

First claim

The invention claimed is:

1. A stainless steel sheet for fuel cell separators,
wherein the stainless steel sheet has a textured structure at a surface thereof, the textured structure having recessed parts and projected parts, and an average interval between the projected parts being 20 nm or more and 200 nm or less, and
a ratio [Cr]/[Fe] of an atomic concentration of Cr existing in chemical form other than metal to an atomic concentration of Fe existing in chemical form other than metal at the surface of the stainless steel sheet is 2.0 or more and 3.7 or less.

2. A production method for a stainless steel sheet for fuel cell separators, the production method comprising:
preparing a stainless steel sheet as a material;
subjecting the stainless steel sheet prepared, to etching treatment; and
subjecting the stainless steel sheet subjected to the etching treatment, to condensation treatment for Cr existing in chemical form other than metal at a surface of the stainless steel sheet,
thereby forming a textured structure having recessed parts and projected parts at the surface of the stainless steel sheet, wherein an average interval between the projected parts is 20 nm or more and 200 nm or less, and a ratio [Cr]/[Fe] of an atomic concentration of Cr existing in chemical form other than metal to an atomic concentration of Fe existing in chemical form other than metal at the surface of the stainless steel sheet is 2.0 or more and 3.7 or less.

3. The production method for a stainless steel sheet for fuel cell separators according to claim 2 , wherein the etching treatment is immersion in a solution containing hydrofluoric acid.

4. The production method for a stainless steel sheet for fuel cell separators according to claim 2 , comprising
subjecting, before the etching treatment, the stainless steel sheet to electrolysis by anodic electrolysis, cathodic electrolysis, or a combination of anodic electrolysis and cathodic electrolysis.

5. The production method for a stainless steel sheet for fuel cell separators according to claim 2 , wherein the condensation treatment is immersion in an oxidizing solution or electrolysis in a potential range in which the stainless steel sheet is passivated.

6. The production method for a stainless steel sheet for fuel cell separators according to claim 3 , comprising
subjecting, before the etching treatment, the stainless steel sheet to electrolysis by anodic electrolysis, cathodic electrolysis, or a combination of anodic electrolysis and cathodic electrolysis.

7. The production method for a stainless steel sheet for fuel cell separators according to claim 3 , wherein the condensation treatment is immersion in an oxidizing solution or electrolysis in a potential range in which the stainless steel sheet is passivated.

8. The production method for a stainless steel sheet for fuel cell separators according to claim 4 , wherein the condensation treatment is immersion in an oxidizing solution or electrolysis in a potential range in which the stainless steel sheet is passivated.

9. The production method for a stainless steel sheet for fuel cell separators according to claim 6 , wherein the condensation treatment is immersion in an oxidizing solution or electrolysis in a potential range in which the stainless steel sheet is passivated.

Assignees

• Jfe Steel Corp

Inventors

• Yano Takayoshi
• Ishikawa Shin

Classifications

• H01M8/0258

  characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant · CPC title

• C23F1/28 Primary

  for etching iron group metals · CPC title

• Y02E60/50

  Fuel cells · CPC title

• C25D11/38

  Chromatising · CPC title

• C23F17/00 Primary

  Multi-step processes for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by subclass C21D or C22F or class C25 (coating for obtaining at least two superposed coatings either by methods not provided for in a single one of main groups C23C2/00 - C23C26/00, or by combinations of methods providedfor in subclasses C23C and C25D, C23C28/00) · CPC title