US 11,923,580 B2
Stainless steel for fuel cell separator plate and manufacturing method therefor
Kwang Min Kim, Pohang-si (KR); Jong Hee Kim, Daejeon (KR); Ki Hoon Jo, Pohang-si (KR); and Bo Sung Seo, Pohang-si (KR)
Assigned to POSCO CO., LTD, Gyeongsangbuk-Do Pohang-si (KR)
Appl. No. 15/747,973
Filed by POSCO, Pohang-si (KR)
PCT Filed Jul. 29, 2016, PCT No. PCT/KR2016/007557
§ 371(c)(1), (2) Date Jan. 26, 2018,
PCT Pub. No. WO2017/052047, PCT Pub. Date Mar. 30, 2017.
Claims priority of application No. 10-2015-0133565 (KR), filed on Sep. 22, 2015.
Prior Publication US 2018/0219201 A1, Aug. 2, 2018
Int. Cl. H01M 8/1018 (2016.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/18 (2006.01); C22C 38/20 (2006.01); C22C 38/22 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01); C23F 1/28 (2006.01); C23G 1/08 (2006.01); C25F 3/06 (2006.01); C25F 5/00 (2006.01); H01M 8/021 (2016.01); H01M 8/0217 (2016.01); H01M 8/0228 (2016.01); H01M 8/1004 (2016.01)
CPC H01M 8/1018 (2013.01) [C22C 38/001 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/18 (2013.01); C22C 38/20 (2013.01); C22C 38/22 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C23F 1/28 (2013.01); C23G 1/086 (2013.01); C25F 3/06 (2013.01); C25F 5/00 (2013.01); H01M 8/021 (2013.01); H01M 8/0219 (2013.01); H01M 8/0228 (2013.01); H01M 8/1004 (2013.01); Y02P 70/50 (2015.11)] 4 Claims
OG exemplary drawing
 
1. A stainless steel for a fuel cell separator plate comprising:
a stainless base material and
a passive film formed on the stainless base material, wherein a content of Si atoms in the passive film is less than or equal to 0.1 at %, a Cr/Fe atomic weight ratio in the passive film is greater than or equal to 1.0, the passive film has an interfacial contact resistance of 10 mΩcm.sup2 (100 N/cm2) or less, and the passive film has a corrosion potential of 0.3 VSCE or more,
wherein the Cr/Fe atomic weight ratio at an interface between the stainless steel base material and the passive film is greater than or equal to 0.65,
wherein the interface between the stainless base material and the passive film refers to a point in the stainless steel at which a content of oxygen accounted for 50% with respect to a maximum content of oxygen as determined in an elemental distribution measured in a thickness direction of the stainless steel, and
wherein the stainless base material at a region starting from 0.5 nm from the interface between the stainless base material and the passive film to 1 nm from the interface between the stainless base material and the passive film after film modification has a Cr/Fe atomic weight ratio of 0.45 or more.