Ion transport mechanisms in the passive film formed on 304L stainless steel studied by ToF-SIMS with 18O isotopic tracer
By Wang, Luntao; Voyshnis, Svetlana; Seyeux, Antoine; Marcus, Philippe
Published in Corrosion Science
2020
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 18O2 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.