Comparative degradation of nickel aluminized by slurry and by pack cementation under isothermal conditions

Oxidation Resistance of Thermal Barrier Coatings Based on Hollow Alumina Particles

“…In contrast, the coated superalloys exhibited an evolution from h to a-Al 2 O 3 with increasing temperature in agreement with the well-known third element effect that Cr procures to develop a-Al 2 O 3 scales rapidly [17]. However, one must bear in mind that the greatest kinetics of the slurry coatings can be related to further oxidation of remnants of metallic Al in the spheres after the coating elaboration process [7]. Further extension to 500 and 1000 h of oxidation displayed less differences in terms of specific mass gain compared to a low activity b-NiAl.…”

“…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 ? c 0 -Ni 3 Al transformation than in conventional low activity b-NiAl although both systems grew duplex NiAl 2 O 4 /Al 2 O 3 scales.…”

Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

“…This research was focused on the changes taking place in aluminium particles to be used in slurries to aluminize stainless steels and Ni-base superalloys [9][10][11]. 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.…”

Comparison of microstructure and oxidation behavior between Pt-free and Pt-modified δ-Ni 2 Si coatings on Ni-based superalloys

“…It has been demonstrated that the long-term oxidation and corrosion resistance of the superalloys can be substantially improved by a protective metal coatings through chemical modification of the surface to induce the formation of an alumina scale by oxidation [3,4]. The pack cementation, a diffusion coating formation process, is widely used to deposit high-temperature oxidation-and corrosion-resistant coatings on Ni-based superalloys [5][6][7]. Current state-of-the-art diffusion coatings for protecting the nickel-base superalloy components at high temperatures are mostly based on either ␤-(Ni, Pt)Al or MCrAlY (M = Ni, Co or Ni + Co), both of which possess high aluminum content and can form a dense thermally grown oxide (TGO) scale of Al 2 O 3 that acts as a diffusion barrier, substantially reducing the rate of oxidation [8][9][10].…”