Study on the Corrosion Behavior of Austenitic Steel HR3C in Supercritical Carbon Dioxide at 550 -600 ℃

Corrosion behavior of austenitic steel HR3C in supercritical CO2 at 550-600 °C under 25 MPa for 1000 h was investigated. The corrosion kinetics of HR3C was evaluated by weight change measurements. Microstructure and phase composition of HR3C was studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and secondary ion mass spectroscopy. Weight gain data showed that the HR3C exhibited the excellent corrosion resistance and corrosion kinetics followed near-parabolic law. The surface of the sample is composed of fine granular oxides, with the main elements including C, O, Cr, Fe and Ni. The oxide phase analysis indicated that protective Cr2O3 formed and a small number of Fe2O3 was also detected. Carbon enrichment was observed at the outmost layer surface and the interface of oxide layer and substrate. The corrosion mechanism and carbon diffusion process were furthermore discussed.