Academic thesis

David Bitter: Back
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Abstract: Aquatic ecosystems form a complex corrosive medium for ferrous materials. Various chemical, physical and biological factors affect the metal, even immediately after the entry of an iron object into the immersion medium. The aim of the work was to investigate whether a correlation exists between the corrosion products on a selection of different objects and the corrosion-determining parameters of the respective water body (brackish water, saltwater / mud flats and running waters). A further aim was to reconstruct the various corrosion processes through an examination of the corrosion layer stratigraphy by means of X-ray images and cross sections, as well as the identification of the corrosion products formed. It could be ascertained that most of the finds from the Wadden Sea, the Gera and the Baltic Sea show high levels of degradation of the metallic substance and, for the most part, corrosion products of iron sulphides. Iron sulphides, however, can only form under biological activity in natural waters. Main players in the so-called microbially induced corrosion are sulfate-reducing bacteria (SRB). These bacterial species live anaerobically, under largely oxygen-poor to oxygen-free conditions. As the most important parameter in the corrosion medium, the oxygen concentration as well as the strength of the oxygen diffusion towards the metal surface could be defined. On the basis of the results of the investigation, it was finally possible to identify some of the parameters acting on the site as being particularly corrosive with regard to the activity of SRB. In conclusion, an estimation of the probability of biocorrosion in the different types of waters, depending on the environmental parameters, could be made. Information that can be helpful not only for the in situ preservation of archaeological find complexes, but also for the understanding of the corrosion processes.

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Details:
  • academic institution: FH Erfurt
  • kind of theses:  Masterarbeit
  • date:  2019
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