The composition and morphology of oxide films formed on type 304 stainless steel in lithiated high temperature water

The morphology and composition of oxide films formed on type 304 stainless steel surfaces exposed to 300°C water at pH 10 have been examined. Emphasis was placed on characterizing the initial stages of oxidation. A correlation was found between oxide film thickness and average crystallite size. The outer, crystalline, part of the oxide was found to be Fe-rich; the inner, amorphous, layer was Cr-rich. Increases in film thickness were found to occur via thickening of the Cr-rich layer. It was also found that chemically pickled surfaces, which were Cr-rich relative to mechanically polished surfaces, were less susceptible to crystallite deposition than the polished surfaces.