Influence of reactive element oxide coatings on the high temperature cyclic oxidation of chromia-forming steels

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 363; no. 1-2; pp. 116 - 125
• Main Authors: Chevalier, S., Larpin, J.P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 20.12.2003; Elsevier
• Subjects: Applied sciences; Corrosion; Corrosion mechanisms; Cyclic experiments; Exact sciences and technology; Metals. Metallurgy; MOCVD coatings; Nd2O3; Oxide scale adhesion; Reactive element effect; Y2O3; Yb2O3; Y2O3; Cyclic experiments; MOCVD coatings; Nd2O3; Reactive element effect; Oxide scale adhesion; Yb2O3; Scanning electron microscopy; Experimental study; X ray diffraction; Alloy steel; Thermal shock; Oxidation; Spallation; Microstructure; Grain boundary segregation
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(03)00592-6

The beneficial effects of reactive element oxide coatings, Y2O3, Nd2O3 and Yb2O3, on the cyclic oxidation behaviour of a Fe–30Cr model alloy, were studied at 950°C in air under atmospheric pressure. The oxide scale grown on uncoated samples started to spall after 2 cycles, because of its poor adherence. The coated specimens remarkably resisted to the thermal shocks, since no oxide scale spallation or cracks could be observed, even after 1000h of cycling experiments. The surface oxide scale consisted of facetted oxide grains on the uncoated samples. On the contrary, it exhibited a fine-grained structure on the coated specimens. The reactive element beneficial effect was ascribed to reactive element ions or second phase particles segregation along the chromia grain boundaries, minimising the chromium cation outward diffusion.