Heterogeneous corrosion of carbon steel used for casing in deep geological radioactive waste repository in contact with claystone

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The corrosion of C-steel in contact with the Cox claystone was studied under aerated conditions at 50°C, for 7 years, in a simplified laboratory experiment. A multi-scale and multi-technique approach, including SEM-EDX, Raman spectroscopy and STXM, was used to determine the nature and structure of the corrosion products and to better understand the mechanisms involved in the observed degradation. The effects of temperature, oxygen supply and the local influence of the composition and density of the claystone were examined here. • Corrosion products were mainly composed of goethite. • Sulphides formed on the bare metal surface even in aerated conditions. • Samples closer to the oxygen source were heavily corroded. • Dense claystone favoured the formation of phyllosilicates in the goethite matrix.