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论文类型：期刊论文

发表时间：2012-01-01

发表刊物：JOURNAL OF THE ELECTROCHEMICAL SOCIETY

收录刊物：SCIE、EI、Scopus

卷号：159

期号：8

页面范围：C319-C325

ISSN号：0013-4651

摘要：Passive films of a high nitrogen face-centered-cubic (f.c.c.) phase (gamma(N)) formed on the plasma-based low-energy nitrogen ion implanted AISI 316L austenitic stainless steel with no pitting corrosion in 3.5% NaCl aqueous solution were investigated by using electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis. The protective passive films on the gamma(N) phase layer were obtained as n-type and p-type semiconductors in the potential range above and below the flat band potential, respectively, which corresponded to the two regions structure: the iron hydroxide/oxides in the outer region and the chromium hydroxide/oxides and iron oxides accompanying the chromium and iron nitrides in the inner region. The gamma(N) phase layer has a maximal phase angle of 83 degrees with an impedance slope of about -0.91 over a wider frequency range approximately from 10(-2) Hz to 10(5) Hz. The donor and acceptor densities of the gamma(N) phase layer decreased approximately from 2.4x10(21)/cm(3) to 6.9x10(18)/cm(3) and from 2.9x10(21)/cm(3) to 5.2x10(19)/cm(3), and the flat band potential decreased approximately from -547 mV(SCE) to -669 mV(SCE), relative to that of the original austenitic stainless steel. The nitrogen beneficial effect in the gamma(N) phase layer on the pitting corrosion resistance contributed to inhibiting the adsorption of aggressive chloride ions in the outer n-type iron hydroxide/ oxides region, to restricting the migration of space charges as a complete barrier from the n-type and p-type semiconductors regions, and to neutralizing of the protons due to the formation of ammonia in NaCl solution. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.007208jes] All rights reserved.