The role of formation of continues thermally grown oxide layer on the nanostructured NiCrAlY bond coat during thermal exposure in air

Microstructural characterisation of air plasma sprayed nanostructure ceramic coatings on Mg–1%Ca alloys (bonded by NiCoCrAlYTa alloy)

“…However, in coatings with higher percentages of nano-zones, the molten part of the semimolten agglomerates cannot fully diffuse into the capillaries of their non-molten cores during the plasma spraying process [23,42,[49][50][51]. This phenomenon would lead to the formation of porous and brittle nano-zones, which were observed in the air plasma-sprayed nanostructure Al 2 O 3 -13 wt% TiO 2 coating.…”

Microstructure and oxidation resistance of cryomilled NiCrAlY coating by laser induction hybrid rapid cladding

“…Especially, when NiCrAlY powder is processed by high-energy milling, the oxidation resistance of cryomilled NiCrAlY coating produced by HVOF spraying has been improved significantly, which has received extensive attention [6,12,20]. The reason is that the cryomilling process is used to produce nanocrystalline NiCrAlY powder and subsequently the nanostructured NiCrAlY coating can be obtained by HOVF spraying [20].…”

“…The reason is that the cryomilling process is used to produce nanocrystalline NiCrAlY powder and subsequently the nanostructured NiCrAlY coating can be obtained by HOVF spraying [20]. The presence of Al 2 O 3 particles in the cryomilled powder and the increasing of Al diffusion through the grain boundaries favor the formation of a continuous α-Al 2 O 3 scale on the surface of NiCrAlY coating, which in turn leads to an increase in oxidation resistance.…”

A magnetron sputtered microcrystalline β-NiAl coating for SC superalloys. Part I. Characterization and comparison of isothermal oxidation behavior at 1100°C with a NiCrAlY coating

“…An ideal TGO should be slow growing, continuous, and adherent to BC. As ␣-Al 2 O 3 has extremely low self and impurity diffusion rates, and its chemical and thermal stability is relatively high, ␣-Al 2 O 3 is preferred to other oxides such as NiO, Cr 2 O 3 , Ni(Al,Cr) 2 O 4 , and -Al 2 O 3 [4][5][6][7]. To form and maintain the growth of ␣-Al 2 O 3 scale at high temperatures, a high Al content is demanded for a good BC.…”