Transformation Kinetics of Oxide Formed on Noble Metal-Treated Type 304 Stainless Steel in 288°C Water

Abstract

The effect of noble metal treatment on the oxides formed on Type 304 (UNS S30400) stainless steel (SS) in high-temperature water containing excess hydrogen was examined by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). The electrochemical corrosion potential (ECP) of noble metal-treated Type 304 SS electrodes was also measured to confirm the presence of catalytically active noble metal on the oxide surface. It was observed that under excess hydrogen water chemistry condition, the presence of Pt and Rh on the oxide surface promotes the transformation of ±-Fe2O3 to a spinel Fe3O4 type, and when Zn is also present, a Zn-enriched outer oxide particle and a Cr-enriched inner oxide layer. The iron concentration in water is, thereby, increased.