Roles of nano-sized oxide particles dispersion on corrosion resistance of ODS alloys in super critical pressurized water

Full text of publication follows: Oxide dispersion strengthened (ODS) ferritic steels with high chromium content have been recently considered as one of the most promising candidates for the fuel cladding materials of super critical pressurized water (SCPW) reactor, due to the superior corrosion resistance and sufficient high-temperature strength of these materials. However, in spite of a lot of efforts to reveal the mechanism of the excellent corrosion resistance of ODS ferritic steels, the details, especially the roles of nano-sized oxide particles, have not been obviously cleared yet. In this study, the corrosion behavior of pure Fe and Fe-16wt.%Cr model alloys with and without dispersing oxide particles was investigated to make clear the oxide dispersion effect on corrosion resistance. And the behavior was compared with that of ODS ferritic steels. The corrosion measurements were conducted in the open-loop system of SCPW at 783 K under a pressure of 25 MPa for time periods up to 600 h. The corrosion rate was evaluated by the weight gain per unit surface area. Preliminary results showed that fine oxide particles caused the formation of rather homogeneous oxide film on the specimen surfaces. In order to understand the mechanism, the morphology, thickness and chemical compositions of the surface oxide film were characterized by means of SEM, SAXS, FEEPMA and FE-AES. (authors)