Abstract
HVOF MCrAlY (M=Ni, Co) coatings were isothermally oxidized in synthetic airbetween 850 and 1050°C for times up to 167 hr. During thermal spraying,aluminum and yttrium oxidized to form a fine oxide dispersion. The HVOFMCrAlY coatings exhibited a microstructure similar to ODS alloys. The finedispersion consisted of Al2O3 and aluminum–yttriumoxides. The oxidation experiments showed that the oxidation rate of HVOFcoatings was two times slower than the oxidation rate of VPS MCrAlYcoatings. The oxidation mechanism changed mainly in the transient-stage(no metastable modification of Al2O3 formed) and it wasassumed that the oxide dispersion hindered diffusion of various elementsfrom the bulk material during oxidation. The formation of the fine oxidedispersion also influenced the adherence of the oxide scale. Themicrostructures of the transient oxide scales were examined by X-raydiffraction (XRD) scanning electron microscopy (SEM), and transmissionelectron microscopy (TEM).
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Toma, D., Brandl, W. & Köster, U. The Characteristics of Alumina Scales Formed on HVOF-Sprayed MCrAlY Coatings. Oxidation of Metals 53, 125–137 (2000). https://doi.org/10.1023/A:1004586814837
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DOI: https://doi.org/10.1023/A:1004586814837