Diffusion and growth mechanism of Al2O3 scales on ferritic Fe-Cr-Al alloys

Mass-Transfer Mechanism of Alumina Ceramics under Oxygen Potential Gradients at High Temperatures

“…The oxygen grain boundary diffusion coefficients determined by this procedure are larger than those determined from extrapolated diffusion data for polycrystalline -Al 2 O 3 annealed in a homogeneous environment without any oxygen potential gradients. 11,12,14) The corresponding activation energies 13) derived by the double oxidation technique are smaller than those for obtained by annealing. 11,12,14) It is currently unclear why these phenomena are induced by oxygen potential gradients.…”

“…Many studies have investigated oxygen grain boundary diffusion in polycrystalline -Al 2 O 3 by using either secondary ion mass spectroscopy (SIMS) [11][12][13] or nuclear reaction analysis (NRA) 14) to determine 18 O depth profiles after high temperature exchange with 18 O-enriched oxygen. Messaoudi et al had reported that the oxygen grain boundary diffusion coefficients are determined from the transport through the growing Al 2 O 3 scale.…”

“…Messaoudi et al had reported that the oxygen grain boundary diffusion coefficients are determined from the transport through the growing Al 2 O 3 scale. 13) This is done by oxidizing the alumina forming alloys in an 16 O 2 atmosphere, further oxidizing them in 18 O 2 and then determining the 18 O distribution in the -Al 2 O 3 scale using SIMS. The oxygen grain boundary diffusion coefficients determined by this procedure are larger than those determined from extrapolated diffusion data for polycrystalline -Al 2 O 3 annealed in a homogeneous environment without any oxygen potential gradients.…”

Microstructure et chimie du substrat

“…Pour les alliages alumino-formeurs dopés en éléments actifs (éléments des terres rares introduits en faible quantité), sous forme métallique ou dispersoïde d'oxydes en quantité contrôlée [23], la couche d'alumine qui se développe à haute température est plus compacte et adhérente au substrat. Les alliages renforcés par dispersion d'oxydes (ODS) allient, grâce à l'ajout du dispersoïde, une bonne résistance mécanique et une bonne résistance à l'oxydation [24].…”

Diffusion and Bonding Mechanism of Protective γ-Al2O3on FeCrAl Foil for Metallic Three-Way Catalytic Converter

“…The alumina scale grows exclusively by oxygen diffusion along grain boundaries. Diffusion results were also obtained in alumina developed on γ-NiAl by cationic and anionic self diffusion tests and also by an electrochemical method [21].…”