The Effect of CeO sub 2 Coatings on the Oxidation Behaviour of Fe--20Cr Alloys in Oxygen at 1173K

The influence of 4 nm thick CeO sub 2 coatings on the oxidation resistance of Fe--20Cr at 1173K in 1 Torr O for periods up to 19 h was examined using exp 18 O/SIMS, TEM and SEM/EDX. Finely dispersed CeO sub 2 became incorporated into the oxide scale and promoted the formation and retention of an adherent layer, which grew at a rate about ten times lower than that of the base alloy. Sequential oxidation experiments in O sub 2 and exp 18 O sub 2 confirmed a change in growth mechanism for the coated alloy from predominantly cation to predominantly anion diffusion. Ceria likely present at oxide grain boundaries blocks cation diffusion outwards, allowing inward oxygen transport to predominate. Graphs, Photomicrographs. 34 ref.--AA