Cyclic and Isothermal Oxidation at 1,100 °C of a CVD Aluminised Directionally Solidified Ni Superalloy

Bouchaud, B.; Balmain, J.; Pedraza, F.

doi:10.1007/s11085-008-9092-3

Cited by 38 publications

(25 citation statements)

References 51 publications

(62 reference statements)

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“…In contrast, Ta and Ti were found in both at the bond coat/TGO interface and within the IDZ. Such partition was previously reported by Bouchaud et al for Ta [20] and by Pfening and coll. for Ti [21] and can be related to the relatively high diffusion coefficient of both refractory elements in these coating and alloy systems [22].…”

Section: Isothermal Oxidationsupporting

confidence: 85%

“…Additional needle-like precipitates in this area can also ascribed to AlN [25,26] with N from the substrate diffusing outwardly [27,28]. Similar TCPs were also found in the low activity out-of-pack aluminides after oxidation in terms of morphology and extension in a DS superalloy having a composition very alike to that of CM-247LC [20]. Figure 6 displays the mass gains per surface unit of René N5 and PWA 1483 aluminized using the conventional low activity and the slurry methods upon cyclic oxidation at 1100°C in air.…”

Section: Isothermal Oxidationmentioning

confidence: 61%

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Oxidation Resistance of Thermal Barrier Coatings Based on Hollow Alumina Particles

et al. 2015

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Thermal barrier coatings were synthesized in a single step process from a slurry containing Al microspheres onto different Ni-based superalloys. Upon growth of the coating a top coat of hollow alumina spheres linked to an aluminium diffused coating through an alumina TGO formed. The isothermal and cyclic oxidation tests at different temperatures (900 till 1100°C) up to 1000 h or 1500 cycles revealed progressive growth of different thermal oxides depending on the substrate composition. Faster degradation of the coatings occurred in the titanium-rich substrates (e.g. IN-738LC and PWA1483) compared to the titanium-poor ones (CM-247LC and René N5). By comparing with conventional low activity aluminide coatings, it appeared that the incorporation of alloying elements (notably Ti and Ta) to the diffused layers upon the high activity slurry coating process is responsible for such fastest degradation.

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Section: Isothermal Oxidationsupporting

confidence: 85%

Section: Isothermal Oxidationmentioning

confidence: 61%

Oxidation Resistance of Thermal Barrier Coatings Based on Hollow Alumina Particles

et al. 2015

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“…The first is the development of slurries for oxidation protection of components at high temperature [1]. The majority of efforts has been devoted to the use of aluminium powder as an additive for propellants, explosives and pyrotechnics.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

et al. 2013

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Oxidized aluminium microparticles have recently been proposed for manufacturing new, environmentally-friendly, protective coatings on stainlesssteels and Ni-base alloys. The oxidation mechanisms of spherical aluminium microparticles of an average particle size of 3.5 lm were studied. Accordingly, simultaneous differential thermal analysis-thermogravimetry tests were carried out in air at different temperatures, always above aluminium melting temperature. Scanning electron microscopy and XRD were also used for the interpretation of results. Weight gain and energy results were explained in terms of the different structural changes taking place in aluminium particles. Dehydroxylation process was identified. The transformation of amorphous alumina to c-Al 2 O 3 was numerically evaluated and the alumina phase transformation (c-Al 2 O 3 ?a-Al 2 O 3 ) was also studied. The temperature ranges revealed the appearance of metastable phases (h-Al 2 O 3 ). Complete oxidation of particles can be obtained at 1,300°C in \1 h, although this also takes place at lower temperatures if enough oxidation time is used. Activation energy of oxidation process at high temperature was also estimated, taking a value of 334 kJ/mol. High temperature oxidation causes the formation of hollow alumina spheres, without any aluminium left inside them.

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“…b) Ni‐based superalloy substrates. The coated CM‐247 exhibits the typical outwardly grown microstructure of a low activity out‐of‐pack aluminising giving rise to surrounded ridges at the grain boundaries . The average grain size is of about 43 ± 2 µm and the mean Al content at the surface is of about 33 wt%, i.e.…”

Section: Resultsmentioning

confidence: 99%

Influence of water vapour on the oxidation behaviour of a conventional aluminide and a new thermal barrier coating system sintered from a slurry

Brossard

Bouchaud

Pedraza

2013

Materials & Corrosion

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In this work, the effect of water vapour on a new thermal barrier coating system synthesised from a slurry containing Al microparticles was studied under isothermal regime at 1100 °C for short oxidation times (50 h). Both dry air and argon gas atmospheres were investigated with increasing water vapour contents (0, 5, 10% RH, relative humidity) and the oxidation mechanisms and growth kinetics of the oxide scales were compared to conventional aluminide coatings up to 50% RH. The phase transformations occurring in the coating were characterised by local Raman micro‐spectrometry with complementary analytical techniques (X‐ray diffraction and FEG‐ESEM/EDS). The results demonstrated that water vapour does not exert a great influence on the oxidation of this type of coatings once an α‐Al2O3 scale is stabilised after an appropriate sintering of the coating. In contrast the combined effect of water vapour and oxidation onto oxide scales grown from raw aluminide coatings was shown to trigger delayed transformation of θ into α‐Al2O3, the appearance of pores and spallation, in particular in air + x %RH.

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Cyclic and Isothermal Oxidation at 1,100 °C of a CVD Aluminised Directionally Solidified Ni Superalloy

Cited by 38 publications

References 51 publications

Oxidation Resistance of Thermal Barrier Coatings Based on Hollow Alumina Particles

Oxidation Resistance of Thermal Barrier Coatings Based on Hollow Alumina Particles

Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

Influence of water vapour on the oxidation behaviour of a conventional aluminide and a new thermal barrier coating system sintered from a slurry

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