Search Results

You are looking at 1 - 2 of 2 items for :

  • Author or Editor: Z. Szilágyi x
  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

57Fe-conversion electron Mössbauer spectroscopy (CEMS) — a sensitive tool to analyze the phase composition of corrosion products on the surface of stainless steel — was applied to study real specimens from the Paks Nuclear Power Plant, Hungary. The primary circuit side of the heat exchanger tubes was studied on selected samples cut out from the steam generators during regular maintenance. Mostly Cr-and Ni-substituted magnetite, amorphous Fe-oxides/oxyhydroxides as well as the signal of bulk austenitic steel of the tubes were detected. The level of Cr-and Ni-substitution in the magnetite phase could be estimated from the Mössbauer spectra. It is suggested that Cr-Ni substitution occurs simultaneously so that the inverse spinel structure of magnetite is preserved up to a certain limit which appears to be roughly at [Fe3+]tet[Fe2+ 1/4Ni2+ 3/4Fe3+ 1/4Cr3+ 3/4]octO4. Further decrease of the iron content of this phase results in the formation of nickel chromite of regular spinel structure, with very low Fe content. This transformation may be responsible for the hybrid structure of the protective oxide layer, being substantially accelerated by previously performed, factory developed and proposed AP-CITROX decontamination cycles.

Restricted access

Summary  

This paper describes the Mössbauer investigations of iron(III) salts in aqueous solutions in the presence of indole-3-alkanoic acid ligands. The measurements showed two parallel reactions between the ligands and ferric ions: a complex formation and a redox process. The oxidation process takes place in the ligands, and a part of Fe3+is reduced to Fe2+.

Restricted access