Oxidação cíclica em alta temperatura de ligas ferrosas fundidas de baixo custo

Malafaia, Artur Mariano de Sousa

doi:10.11606/t.18.2013.tde-15012014-103642

Cited by 3 publications

(3 citation statements)

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“…At the referred layer, the main crystalline phase is hematite, followed by magnetite. For the incident angles between 0.5° and 1.5°, an average hematite / magnetite ratio of 60% per 40% is maintained, which was also reported by other studies [14,15]. However, for angles higher than 2°, the magnetite fraction increased, and at 3° the results presented also martensite peaks (charac teristic peaks of α ' Fe (110), (200) and ( 211)).…”

Section: Resultssupporting

confidence: 85%

“…However, in Fig. 5 and [14,15]. This result was corroborated by Mössbauer spectroscopy on CEMS that con rms the presence of the sextet referring to the formation of hematite oxide, as presented in Fig.…”

Section: Resultssupporting

confidence: 71%

“…Malafaia and Shreir et al [14] proposes the formation of three overlapping layers: the outermost, composed by hematite or iron oxide II (Fe 2 O 3 hexagonal compact is considered the highest state of iron oxidation, with almost 70 at.% iron in its composition, while oxygen occupies the other 30 at.%) ; an intermediate one corresponds to the magnetite oxide (Fe 3 O 4 -CFC) and the inner one by wustite (FeO -CFC) [14,15]. These three layers act together as a barrier to the progress of oxidation and also hinders the hydrogen uptake, thus playing a vital role in reducing hydrogen damage [16].…”

Section: Introductionmentioning

confidence: 99%

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Structural Characterization of Iron Oxide Grown On 18% Ni-Co-Mo-Ti Ferrous Base Alloy Aged Under Superheated Steam Atmosphere

Cardoso

Igreja

Garcia

et al. 2021

Preprint

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18% Ni-Co-Mo-Ti Ferrous base alloys are special materials, widely used in the industry of isotopic enrichment after specific annealing and aging thermal treatment. The desirable high mechanical properties can then be attained by adequate aging heat treatment, answering the structural materials specifications required by defense applications in aerospace and nuclear engineering. For instance, the isotopic enrichment, in rocket engine envelope application, when associated with high temperature and chemical residues like acidic solutions, can induce corrosion and hydrogen embrittlement in martensite structures. To limit these corrosion and hydrogen embrittlement phenomena, an adherent and protective layer of iron oxides can be grown on the material surface by using adequate atmosphere during the aging treatment. Due to its application in strategic areas, the characterization of these oxide layers in maraging steels is of importance as well as the understanding of their growth kinetics. For this purpose, several techniques, such as Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES), Microabrasive wear testing, Hardness, Grazing Incidence X-ray Diffraction (GIXRD) and X-ray Photoelectron Spectroscopy (XPS), have been performed for chemical and structural characterization of the oxide films formed after vapor exposed thermal aging at 510°C . The oxide layer consists mostly in two sub-layers composed by magnetite (Fe3O4) and an external layer of hematite (Fe2O3). A thick interface between the oxide layer and the bulk is enriched in Ti and Mo, whereas the analyses of deep bulk material show an enriched area with Ni and Co.

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Section: Resultssupporting

confidence: 85%

Section: Resultssupporting

confidence: 71%