The characteristics of alumina scales formed on HVOF-sprayed MCrAlY coatings[High Velocity Oxygen Fuel]
HVOF MCrAlY (M = Ni, Co) coatings were isothermally oxidized in synthetic air between 850 and 1050 C for times up to 167 hr. During thermal spraying, aluminum and yttrium oxidized to form a fine oxide dispersion. The HVOF MCrAlY coatings exhibited a microstructure similar to ODS alloys. The fine dispersion consisted of Al{sub 2}O{sub 3} and aluminum-yttrium oxides. The oxidation experiments showed that the oxidation rate of HVOF coatings was two times slower than the oxidation rate of VPS MCrAlY coatings. The oxidation mechanism changed mainly in the transient-stage (no metastable modification of Al{sub 2}O{sub 3} formed) and it was assumed that the oxide dispersion hindered diffusion of various elements from the bulk material during oxidation. The formation of the fine oxide dispersion also influenced the adherence of the oxide scale. The microstructures of the transient oxide scales were examined by X-ray diffraction (XRD) scanning electron microscopy (SEM), and transmission electron microscopy (TEM).
- Research Organization:
- Univ. of Gelsenkirchen (DE)
- OSTI ID:
- 20015578
- Journal Information:
- Oxidation of Metals, Vol. 53, Issue 1-2; Other Information: PBD: Feb 2000; ISSN 0030-770X
- Country of Publication:
- United States
- Language:
- English
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