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Effect of sulphur on the formation of graphite at the surface of carburized iron
Author(s) -
Moszyński D.,
Grabke H. J.,
Schneider A.
Publication year - 2002
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.1321
Subject(s) - cementite , graphite , sulfur , nucleation , auger electron spectroscopy , metallurgy , chemistry , materials science , surface layer , decomposition , layer (electronics) , inorganic chemistry , nanotechnology , austenite , microstructure , organic chemistry , physics , nuclear physics
The effect of sulphur on the formation of graphite at the surface of carburized iron and the decomposition of cementite were studied by Auger electron spectroscopy (AES). Graphite growth was observed on the iron surface covered with various amounts of sulphur. On the surface with a sulphur coverage of ∼40% a graphite layer was already formed at 400°C. Sulphur islands present on the surface were not influenced by the growing graphite. If the iron surface was saturated with sulphur, graphite growth started only at temperatures of >550°C. In this case, a graphite layer was formed on top of the adsorbed sulphur atoms. The nucleation sites for graphite formation may be grain boundaries, phase boundaries and other crystal defects or vacancies in the sulphur layer. The decomposition of cementite on the sample surface was also studied following the increase of the graphite peak. Coverage of the surface with sulphur led to a substantial decrease of the decomposition rate of cementite. A linear decrease of the rate of cementite decomposition with increasing sulphur concentration on the surface was found. When the cementite surface was saturated with sulphur, the formation of graphite was almost stopped, but even then a slow graphite growth could be observed. Copyright © 2002 John Wiley & Sons, Ltd.