In the framework of a new generation of nuclear reactors, typically Sodium Fast Reactors,
supercritical carbon dioxide with a Brayton cycle (at 550°C and 250 bars) is identified as a promising
energy conversion system to replace the traditional steam generators. Nevertheless, the long-term
integrity of the heat exchanger structure in this environment has to be proven over at least 20 years. For
this reason, the corrosion behavior of the following metallic materials in static carbon dioxide at 550°C
and 250 bars was studied: 9wt% Cr ferritic-martensitic steel (T91) and austenitic alloys, 316L, 800H,
and S30815. The first results about the nature of the corrosion product, and their morphology and
kinetics of formation revealed through surface analyses such as Glow Discharge Optical Emission
Spectroscopy, Scanning Electron Microscopy, Wavelength-Dispersive Spectroscopy and X-Ray
Diffraction are presented. Corrosion mechanisms for the various steels are proposed and the most
promising materials for heat exchanger applications revealed.
Keywords: supercritical carbon dioxide, oxidation, carburization, ferritic-martensitic steel, austenitic
steel