Aiming to simulate the external corrosion of pipelines, the first stages of the inclusion attack and nucleation of pits were studied by AFM on the API 5LX56 steel in pure 10 mM Na2SO4 solutions with additions of humic (HA) and fulvic acids (FA), both extracted from a Brazilian peat soil. For this, selected inclusions were first marked with microindentations, analyzed in the SEM in the backscattering mode and chemically mapped with EDS. Pit formation was then investigated by scanning Kelvin probe force microscopy (SKPFM). The SKPFM evidenced that HA added to sulfate solutions promotes the fast dissolution of the sulfides of complex inclusions, resulting in pit nucleation, while FA additions slow this attack, acting as a natural corrosion inhibitor.
AFM study of the corrosion of pipeline steel in organic compounds extracted from soil
2008
13 Seiten, 9 Bilder, 3 Tabellen, 19 Quellen
Aufsatz (Konferenz)
Englisch
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