Study of the Variation of Chromium Oxide and Iron in Oxide Layer by XPS in DSS 2205 with Higher and Lower Chromium Content Due to Ageing for 7000 Hours at 300°C

The surface oxidation of DSS 2205 duplex stainless steel was studied by X-ray photoelectron spectroscopy (XPS), for two different techniques witch were used to produce thin oxide layers on polished for measuring the concentration of oxide depends on the sputtering profile these duplex stainless steel samples. The experiments were performed in the temperature of 300°C with aging at 7000 hours e with growth of films obtained voltammetric curves (potentiostatically) of the samples in sulfuric acid (H2SO4-0.1M saturated) at low potential. The compositions of the modified oxidized surfaces were determined from the XPS survey scans, and the chemistry of selected elements from the higher-energy-resolution scans of the appropriate peaks. Various Iron/Chromium oxidized layers and various oxide thicknesses were observed and correlated with the temperature. It was found that all the techniques produced oxide layers with various traces of metallic components and with the maximum concentration of chromium oxide and iron oxide in layers close to the oxide layer/metal interface. Therefore this study showed results about the behavior of the DSS 2205 with higher and lower Cr content and that the annealing at 300°C for longer times (7000h) promotes the enrichment of iron oxide, and consequently the decrease in the chromium oxide content, in the oxide surface of both the DSS 2205.