Direct observation of the passive layer on high nitrogen stainless steel used as bipolar plates for proton exchange membrane fuel cells

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• 作者：Masanobu Kumagai^a ; ^b ; ¹ ; Seung-Taek Myung^c ; ¹ ; ^{smyung@sejong.ac.kr} ; Hitoshi Yashiro^d ; Yasuyuki Katada^e ; ^{KATADA.Yasuyuki@nims.go.jp}
• 关键词：High nitrogen stainless steel ; Corrosion resistance ; Bipolar plate ; Fuel cell
• 刊名：Journal of Power Sources
• 出版年：2012
• 期刊代码：58_03787753
• 类别：ce
• 出版时间：15 July, 2012
• 卷：210
• 期：Complete
• 页码：92-95
• 文件大小：769 K

摘要

The purpose of this report is to directly observe the passive layer and concentration behavior of nitrogen interstitially incorporated in Ni-saving high nitrogen stainless steel (HNS) using an aberration corrected scanning transmission electron microscopy-energy dispersive spectroscopy (STEM-EDS) or - electron energy loss spectroscopy (EELS). The thickness of the passive layer barely changed after 1000 h single cell operation, compared with the as-polished state. The observed passive layer was thin (3 nm) and mainly composed of chromium oxide, as confirmed by STEM-EDS. It was confirmed that nitrogen was not present in the passive layer, but was concentrated at the interface between the passive layer and the metal bulk. The concentrated area ranged approximately 2 nm to steel bulk from the interface. With help of the STEM-EDS and EELS, we were able to understand the nature of the passive layer for Ni-saving HNS, which caused remarkable improvement of the cell performance due to superior corrosion resistance.