XPS Analysis of nanolayers obtained on AISI 316L SS after Magnetoelectropolishing

In the present paper, the passive layers' chemical compositions of AISI 316L austenitic stainless steel samples after three treatments, such as mechanical/abrasive polishing (MP), standard electropolishing (EP) and magnetoelectropolishing (MEP) are displayed. For the surface studies after each treatment, XPS analysis was performed. It has been noted that after MP treatment the Cr/Fe ratio in the passive layer is the lowest and equals to about 1, whereas after the MEP it is close to 3. Additionally, it has to be reported that the passive layers after MP consist mainly of Cr2O3 and Fe2O3, after a standard EP treatment – of CrOOH and FeOOH, and after MEP – of Cr(OH)3 and FeOOH compounds. Concerning the surface layer compositions, in the passive layer formed after MP the detected iron consisted partly of Fe0 (46.5 at %) and partly of iron compounds Fe2+ and Fe3+ (53.5 at %), whereas the detected chromium consisted of Cr0 (16.5 at %) and mostly of chromium compounds Cr3+ (80.8 at%), with a small amount of Cr6+ (2.7 at %). In case of the nanolayer after EP treatment, the detected iron consisted of Fe0 (39.5 at %) and iron compounds Fe2+ and Fe3+ (60.5 at %), whereas the detected chromium consisted in a small amount of Cr0 (6.6 at %), and mostly chromium compounds Cr3+ (83.8 at %) with some Cr6+ (9.6 at %). The XPS analysis of nanolayer formed on AISI 316L after MEP indicates that the detected iron consisted partly of Fe0 (27.1 at %) and mostly of iron compounds Fe2+ and Fe3+ (72.9 at %) whereas the detected chromium contained Cr0 (18 at %) and chromium compounds of Cr3+ (76 at %) and Cr6+ (6 at %).