An XPS and XAES study of the nature of the metal/scale interface in air-oxidized Fe/1.0 [formula omitted] Si alloy

• Published in: Corrosion science 1989, Vol.29 (1), p.45-52
• Main Authors: Crossley, J.A.A, Rivière, J.C
• Format: Article
• Language: English
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/0010-938X(89)90079-6

Coupons of an Fe/1.0 w o Si alloy were oxidized in ambient air at 500°C for times between 4 × 10 3 and 10 6 s. The oxide scale was removed from the alloy substrate by a dry-stripping technique previously described, allowing surface analysis of each side of the metal/scale interface thus exposed. Compositional profiles into each side of the interface, to depths between 80 and 200 nm, showed a very similar high concentration of Si at the interface to that found in oxidation in CO 2. However, in contrast, C was virtually absent from the interface, indicating that the build-up of C in that region during oxidation in CO 2 played no part in the oxidation mechanism, although the C deposit in that case is thought to have had other rôles. The chemical state of Si on each side, and during depth profiling, was established from the Auger Parameter Si(KLL-2s), using Bremsstrahlung radiation to excite the KL 2.3L 2.3 Auger peak. As in CO 2 oxidation, the Parameters were different on each side of the interface, and the difference increased with depth, that on the scale side approaching the value for Fe 2SiO 4 while that on the metal side remained almost constant, close to the value for SiO 2. The results were overall very similar to those already found in oxidation of Fe/Si alloys in CO 2, and the mechanism is therefore thought to be the same.