Effect of CeO2 Coatings and Interfacial Segregations of S and C on the Oxidation Behaviour of Fe-Cr Alloys in O2
The influence of 4 nm thick CeO2 coatings and interfacial segregation of S and C on the oxidation resistance of Fe-20Cr at 1173 K in 1 torr oxygen were examined using 18O/SIMS, TEM and SEM/EDX for periods up to 19 hrs. The CeO2 became incorporated into the oxide scale and promoted the formation and retention of an adherent layer displaying a 10 times lower oxidation rate. Tracer studies with 16O/18O have confirmed a change in the oxidation mechanism. During oxidation of both uncoated and coated alloys sulfur and carbon accumulate at the metal/oxide interface. The amount of segregated sulfur does not vary with time, whereas the level of segregated carbon increases. The total amount of segregants was found to be the same in both untreated and coated alloys.