Ion transport mechanisms in the passive film formed on 304L stainless steel studied by ToF-SIMS with 18O isotopic tracer. (15th August 2020)

• Record Type: Journal Article
• Authors: Wang, Luntao; Voyshnis, Svetlana; Seyeux, Antoine; Marcus, Philippe
• Is Part Of: Corrosion science. Volume 173(2020)
• Publication Date: 2020-08-15
• Subjects: Ion transport mechanisms -- Stainless steel -- Passive film -- ToF-SIMS; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2020.108779
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Ion transport in pre-formed passive film on 304L stainless steel is investigated in situ by ToF-SIMS. The pre-formed passive film has a duplex structure with outer iron oxide and inner chromium oxide layers. Exposure to isotopic 18 O2 at 300 °C of the pre-formed film reveals cation diffusion is governing the oxidation process. The apparent diffusion coefficients are determined. The cation diffusion coefficient is found to be markedly higher than the oxygen diffusion coefficient. Abstract: The ion transport in the pre-formed passive film on 304L stainless steel surface has been investigated by in situ ToF-SIMS with isotopic tracer. The passive film, formed electrochemically in sulfuric acid, has a bilayer structure with outer iron oxide and inner chromium oxide layers. Further exposure of the passive film to 18 O2 gas (isotopic tracer) at 300 °C reveals that outward cation diffusion is the governing ion transport mechanism for the oxide growth. The parabolic rate constant for the oxide growth was determined. The cation diffusion coefficient is found to be markedly higher than the oxygen diffusion coefficient.