Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory

O 36.78: Poster

Dienstag, 1. April 2014, 18:30–22:00, P1

Iron surfaces in a sour gas environment — •Mehmet Ali Ilhan, Mira Todorova, and Jörg Neugebauer — Department for Computational Material Design, Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany

Low alloyed steels are particularly susceptible to sour gas corrosion, which leads to the formation of iron sulfides. The developing corrosion products typically do not form protective layers and have no passivating effect. Knowledge of the structure, stability and adhesion of such corrosion products is essential to the evaluation and improvement of their protective properties.

To address these questions we study the interactions of S, H and O with the (100) surfaces of bcc Fe by density-functional theory calculations. We find that the competition between adsorbates can cause H to be pushed below the surface, when S occupies the hollow surface adsorptions sites it prefers, while O/H co-adsorption leads to the formation of OH-groups. Increasing S coverage, on the other hand, leads to the formation of a layered structure, with loosly bound interatomic layers, which resembles Mackinawite (tetragonal FeS). The insight we gain from our calculations, regarding the protective behaviour of the forming corrosion products, will be discussed.