Study on the corrosion resistance properties of a 18Cr-ODS in supercritical water

摘要

The corrosion behavior of a 18Cr-ODS steel exposed in supercritical water (SCW) at600 /25MPa was studied in order to evaluated the suitability of the ODS steel ℃ eel in thesupercritical water reactor (SCWR). The effects of exposure time on the corrosion behaviorwere investigated. Gravimetry, scanning electron microscope/electron dispersive X-rayspectroscopy (SEM/EDS) and X-ray diffraction (XRD) were employed to characterize theoxide layer. The results showed that the weight gain increased as increasing exposure time,following a parabolic law. A layer formed on the surface of the sample consisting of adiffusion layer, a chromium-rich inner layer and an iron-rich outer layer. XRD results showedthat the phases of the outer layer are mainly hematite and magnetite. Hematite contentincreased and magnetite decreased as elapsing of exposure time. Cracks and porosity couldalso be observed on the outer oxide layer. Diffusion plays an important role in the corrosionprocess.