First Stages of Oxidation of Pt-Modified Nickel Aluminide Bond Coat Systems at Low Oxygen Partial Pressure

Alvarado-Orozco, J.M.; Morales-Estrella, Ricardo; Boldrick, M.S.; Ortiz-Merino, J. L.; Konitzer, D.G.; Trápaga, G.; Muñoz-Saldaña, J.

doi:10.1007/s11085-012-9305-7

Cited by 17 publications

(13 citation statements)

References 47 publications

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“…The Al2O3 scale formation causes the Ni inward diffusion to compensate Al depletion which promotes an unbalance in the diffusivity of both elements, forming voids at metal-oxide interface [8,18,19], as can be clearly observed in Figure 4.…”

Section: Resultsmentioning

confidence: 85%

“…According to the analysis, chemical composition gradients are observed from the BC surface to the IDZ boundary. These gradients are result of the coating deposition process, which starts with a Ptelectroplating on a grit-blasted SA substrate, followed by a heat treatment step to promote the Pt diffusion [8]. Later, a low-activity aluminum coating is deposited by chemical-vapor deposition (CVD) technique to finish the BC [14].…”

Section: Resultsmentioning

confidence: 99%

“…Changes in chemical composition along the cross section of the β-(Ni,Pt)Al +IDZ+ René N5 system are shown in the Figure 2 for the samples oxidized at 900 and 1200 o C, and compared with the sample in the as-received condition. These temperatures were selected as known conditionswhere the TGO grow kinetics is mainly controlled by the θ-Al2O3 and α-Al2O3 phases, respectively[8,10]. Chemical composition profiles along the system: bond coat, interdiffusion zone and superalloy in (a) asreceived condition, and after pre-oxidation treatment for 5h in pO2 = 1 x 10 -5 atm at (b) 900 o C and (c) 1200 o C.…”

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confidence: 99%

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Effect of pre-oxidation treatments on the structural, microstructural, and chemical properties of β-(Ni,Pt)Al system

García-Herrera

Espinosa-Arbeláez

Cáceres-Díaz

et al. 2019

Surface and Coatings Technology

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Effect of pre-oxidation treatments on the structural, microstructural, and chemical properties of β-(Ni,Pt)Al system

García-Herrera

Espinosa-Arbeláez

Cáceres-Díaz

et al. 2019

Surface and Coatings Technology

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“…The fraction of a-Al 2 O 3 after 1, 5 and 20 h was estimated using the following approximation 17,18 …”

Section: Resultsmentioning

confidence: 99%

Effect of environmental sulphur on structure of alumina scales formed on Ni-base alloys

Liu

Gleeson

2015

Materials at High Temperatures

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Short term oxidation exposures of an alumina-scale forming c9-Ni 3 Al-base model alloy in air and O 2 z0?1%SO 2 at 900uC revealed that the presence of sulphur can affect the kinetic competition between the h and a structural isomorphs of Al 2 O 3 . After five hours exposure, metastable h-Al 2 O 3 growth predominated in air alone; whereas, a much larger percentage of stable a-Al 2 O 3 formed during oxidation in O 2 z0?1%SO 2 . This promotion of a-Al 2 O 3 establishment was due to sulphur enrichment on the alloy surface, which occurred even when samples were exposed to O 2 z0?1%SO 2 in a low temperature, pre-test position (~150uC), i.e. before insertion into the hot zone. It was determined from X-ray photoelectron spectroscopy measurements that the sulphur was mainly in the S 6z valence state and, correspondingly, in the form of NiSO 4 . It will be discussed that the observed results can be rationalised based on the preferential presence of sulphur at the oxidising surface hindering the h-Al 2 O 3 growth rate to the extent that a-Al 2 O 3 establishment is favoured.

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“…The volume fraction of a-Al 2 O 3 after 1, 2, 5, 10 and 20 h was estimated using the following approximation [34,35].…”

Section: Methodsmentioning

confidence: 99%

Effect of environmental sulfur on the structure of alumina scales formed on Ni-base alloys

et al. 2015

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a b s t r a c tShort-term oxidation exposures of an alumina-scale forming c 0 -Ni 3 Al-based model alloy in air and O 2 + 0.1%SO 2 at 900°C revealed that the presence of sulfur can affect the kinetic competition between the h and a structural isomorphs of Al 2 O 3 . After 2 h exposure, metastable h-Al 2 O 3 growth predominated in air alone; whereas, a much larger percentage of stable a-Al 2 O 3 formed during oxidation in O 2 + 0.1%SO 2 . This promotion of a-Al 2 O 3 establishment was due to sulfur enrichment on the alloy surface, which occurred even when samples were exposed to O 2 + 0.1%SO 2 in a low-temperature, pre-test position ($150°C), i.e., prior to insertion into the hot zone. It was determined from XPS measurements that the sulfur was mainly in the S 6+ valence state and, correspondingly, in the form of NiSO 4 . Cross-sectional scanning transmission electron microscopy (STEM) using energy-dispersive X-ray spectroscopy (EDS) corroborated the XPS results by detecting that a $20 nm zone of sulfur enrichment within the surface region of a $90 nm oxygen-rich layer formed during the pre-test exposure. A systematic explanation for this intriguing observation of sulfur promoting a-Al 2 O 3 establishment is provided from the perspective of kinetics competition between h and a. This explanation was supported by kinetic calculations and complementary tests in a low p O 2 atmosphere.

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First Stages of Oxidation of Pt-Modified Nickel Aluminide Bond Coat Systems at Low Oxygen Partial Pressure

Cited by 17 publications

References 47 publications

Effect of pre-oxidation treatments on the structural, microstructural, and chemical properties of β-(Ni,Pt)Al system

Effect of pre-oxidation treatments on the structural, microstructural, and chemical properties of β-(Ni,Pt)Al system

Effect of environmental sulphur on structure of alumina scales formed on Ni-base alloys

Effect of environmental sulfur on the structure of alumina scales formed on Ni-base alloys

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