材料期刊网

An electrodeposited Ni-CeO(2) composite was used as a "precursor film" for a novel CeO(2)-dispersed chromium coating deposited using a traditional pack cementation method. The substrate was a carbon steel. For comparison, chromium coatings were also prepared on the untreated and pure Ni-film-treated carbon steel using the same pack cementation conditions. Oxidation in 5% O(2) + 40% H(2)O + N(2) at 900 degrees C showed that, compared to the CeO(2)-free coating counterparts, the CeO(2)-dispersed chromium coating exhibited greatly increased oxidation resistance, owing to the development of a denser and more slowly growing chromia scale. The slow growth of the scale was correlated with the CeO(2) dispersion exerting the so-called "reactive elemental effect ( REE)" on oxidation. The oxidation mechanisms in wet air of the various types of coatings were compared to those in dry air and are fully discussed in this work.