Aging and thermal behavior of a PVA/Al microspheres slurry for aluminizing purposes

Rannou, B.; Velasco, F.; Guzmán, S.; Kolarik, V.; Pedraza, F.

doi:10.1016/j.matchemphys.2012.03.002

Cited by 32 publications

(26 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A 6 μm thick Pt layer was then electroplated and subsequently annealed at 1080°C for 1 h under vacuum by Turbocoating, SpA (Italy). The samples were then slurry aluminized by spraying (12 ± 2) mg · cm − 2 of a slurry containing spherical Al micro-particles (2-10 μm range) dispersed in a water/PVA binder onto the samples and drying in laboratory air for 1 h [21]. Subsequently, a two step heat treatment was carried out under argon gas atmosphere.…”

Section: Methodsmentioning

confidence: 99%

Influence of the superalloy substrate in the synthesis of the Pt-modified aluminide bond coat made by slurry

Mollard¹,

Pedraza²,

Bouchaud³

et al. 2015

Surface and Coatings Technology

Self Cite

View full text Add to dashboard Cite

Section: Methodsmentioning

confidence: 99%

Influence of the superalloy substrate in the synthesis of the Pt-modified aluminide bond coat made by slurry

Mollard¹,

Pedraza²,

Bouchaud³

et al. 2015

Surface and Coatings Technology

Self Cite

View full text Add to dashboard Cite

“…Figure 8 shows the TG-DTA analysis of powders during heating up to 950°C, where most important reactions take place. The process taking place at 250-300°C can be related to the desorption of water from the surface of the particles and the subsequent dehydroxylation of the aluminol groups contained in the amorphous layer surrounding the aluminium particles [4,13]. Aluminium particles are covered by a nanometric, amorphous layer of alumina after production processes.…”

Section: Fig 2 Weight Gains During 10 H Isothermal Dwellsmentioning

confidence: 99%

“…A more environmentally-friendly approach for slurries is investigated within the European project ''Particoat' ' [12], in which Al microparticles (1-20 lm) are added to simple mixtures of water (solvent) and organic binders [13] with no additional chemical compounds. It is important to understand the behaviour of aluminium microparticles in air to understand the phenomena taking place during aluminizing.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

et al. 2013

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…The slurry TBCs were obtained from a 1/10 PVA/H 2 O solution to which 45 mass% 5 lm-sized Al microparticles were added [3]. After spray onto four nickel-based superalloys with different composition and crystal structure (Table 1) and dry in air, the slurries were annealed at 700°C/2 h and additional 1100°C/2 h in Ar(g).…”

Section: Methodsmentioning

confidence: 99%

“…This system is often based on a top ceramic coat of yttria stabilized zirconia (YSZ) made by electron beam physical vapour deposition (EB-PVD) with columnar structure to comply with thermal cycling, an intermediate aAl 2 O 3 thermally grown oxide (TGO) to attach the YSZ and to provide oxidation protection and an underlying b-NiPtAl diffusion coating that acts as an aluminium reservoir [1]. New low-cost and environmentally friendly coatings were recently proposed in the European project ''Particoat'' [2] in which a water-based slurry containing Al microparticles was sprayed and annealed [3] onto pure nickel [4] and different nickel-based superalloys [5] or steels [6]. The isothermal oxidation behaviour of these coatings onto a pure Ni [7] and a René N5 superalloy [8] indicated faster oxidation kinetics and faster b-NiAl ?…”

Section: Introductionmentioning

confidence: 99%

Oxidation Resistance of Thermal Barrier Coatings Based on Hollow Alumina Particles

et al. 2015

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Aging and thermal behavior of a PVA/Al microspheres slurry for aluminizing purposes

Cited by 32 publications

References 39 publications

Influence of the superalloy substrate in the synthesis of the Pt-modified aluminide bond coat made by slurry

Influence of the superalloy substrate in the synthesis of the Pt-modified aluminide bond coat made by slurry

Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

Oxidation Resistance of Thermal Barrier Coatings Based on Hollow Alumina Particles

Contact Info

Product

Resources

About