Study of oxide protective layers on stainless steel by AES, EDS and XPS

A protective oxide layer was formed on the surface of stainless steel by standard industrial-type thermal treatment. Additional post-thermal treatment annealing and polishing followed by annealing were applied in an attempt to improve characteristics of the layers. Oxide layers formed on samples without and with different types of post-thermal treatment processing were analysed and compared. Several techniques were employed. SEM was used to image the surface; AES, XPS and energy-dispersive spectroscopy (EDS) were all used to probe the elemental composition of the oxide layers. AES was also used as the most straightforward method to obtain depth profiles. Low beam energy EDS was used in an attempt to obtain some fast averaged volume information from the layers. XPS was mainly used for determining chemical states on the surface of the sample but not for depth profiling (low sputtering rate due to large illuminated area). Analysed samples differed with regard to surface morphology of the oxide layers, oxide layer compositions and thicknesses. An attempt was made to relate these differences to differences in post-thermal treatment procedures. Copyright (c) 2008 John Wiley & Sons, Ltd.