The oxide film formed on 304 stainless steel in high temperature, high purity water containing oxygen, hydrogen and hydrogen peroxide was analyzed by Auger electron microscopy (AES), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and the electrochemical corrosion potential (ECP) measurement was also conducted under various water chemistry conditions. A more rapid shift of ECP to the noble direction was observed when H2O2 was present in 288°C water, compared to the ECP value measured at the same level of O2. This may result from the electrochemical and/or chemical changes on the oxide film. AES data indicates that a thicker oxide was fromed under 200 ppbO2 or 200 ppb H2O2 conditions than under 150 ppb H2. It is evident that the oxide film consists of two layers; the outer oxide layer with different particle sizes and the inner fine grained layer. It was also observed that the structures of the outer oxide particles (large or small) formed in 200 ppb O2, in 200 ppb H2O2, and in 150 ppb H2 are mainly hematite...
Keywords: Oxide, stainless steel, high temperature water, oxygen , hydrogen, hydrogen peroxide, TEM, SEM, AES.