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Fe and Si films were tested as corrosion protection layers for Zr in nuclear industry applications. Surface chemistry of Zr in dependence on the preparation conditions and layout of the films was complexly investigated by various spectroscopic and microscopic techniques. Corrosion experiments were carried out in autoclave conditions with in-situ Electrochemical Impedance Spectroscopy. A clean Zr surface is characteristic with disposition to disorder and rough morphology demonstrated in facets, steps or terraces. Upon deposition of Fe and Si atoms in amounts in the order of single monolayers and subsequent annealing at 400°C, the original (1×1) Zr surface structure rearranges into (2√3×2√3)R30°. Corrosion experiments show that a thicker Si overlayer successfully suppresses oxygen uptake of the underlying Zr material by forming a diffusion barrier. The barrier effect of the films was also confirmed for hydrogen. [ABSTRACT FROM AUTHOR]

If we want to decrease the probability of accidents in nuclear reactors, we must control the surface corrosion of the fuel rods. In this work we used a diamond coating containing <60% diamond and >40% sp2 "soft" carbon phase to protect Zr alloy fuel rods (ZIRLO®) against corrosion in steam at temperatures from 850 °C to 1000 °C. A diamond coating was grown in a pulse microwave plasma chemical vapor deposition apparatus and made a strong barrier against hydrogen uptake into ZIRLO® (ZIRLO) under all tested conditions. The coating also reduced ZIRLO corrosion in hot steam at 850 °C (for 60 min) and at 900 °C (for 30 min). However, the protective ability of the diamond coating decreased after 20 min in 1000 °C hot steam. The main goal of this work was to explain how diamond and sp2 "soft" carbon affect the ZIRLO fuel rod surface electrochemistry and semi conductivity and how these parameters influence the hot steam ZIRLO corrosion process. To achieve this goal, theoretical and experimental methods (scanning electron microscopy, Raman spectroscopy, electrochemical impedance spectroscopy, carrier gas hot extraction, oxidation kinetics, ab initio calculations) were applied. Deep understanding of ZIRLO surface processes and states enable us to reduce accidental temperature corrosion in nuclear reactors. [ABSTRACT FROM AUTHOR]