Influence of reactive element oxide coatings on the high temperature oxidation behavior of alumina-forming alloys

• Published in: Oxidation of metals Vol. 61; no. 3-4; pp. 195 - 217
• Main Authors: CHEVALIER, S, NIVOT, C, LARPIN, J. P
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.04.2004
• Subjects: Applied sciences; Corrosion; Corrosion environments; Exact sciences and technology; Metals. Metallurgy; Oxide layer; Growth; Chromium alloy; Morphology; Oxidation; Aluminium alloy; High temperature; Alumina; Chemical vapor deposition; High temperature corrosion; Iron base alloys
• ISSN: 0030-770X; 1573-4889
• DOI: 10.1023/B:OXID.0000025331.25452.35

Reactive-element-oxide coatings were processed by a metal-organic chemical vapor-deposition technique on the surface of a model FeCrAI alloy. The high temperature performances of Nd2O3-, Y2O3 -coated and uncoated alloys were tested in air under atmospheric pressure at 1050, 1100 and 1200 deg C. The coated samples did not exhibit the expected reactive-element effects since the oxidation rates were not decreased, and the oxide-scale adherence was only slightly improved. The study of the oxide-scale morphology revealed very convoluted oxide scales, except for alumina scales formed on uncoated materials at 1100 and 1200DGC Two-stage oxidation experiments showed that the reaction proceeded by a mixed anionic-cationic diffusion process; consequently, the growth of alumina within the existing alumina layer results in convoluted scales. It is proposed that the weak incorporation of the reactive elements within the thermally growing alumina scales was responsible for the limited reactive element effects, when reactive-elements were applied as oxide coatings on alum ina-forming steels.