Aluminization of nickel-formation of intermetallic phases and Ni2Al3 coatings

Formation of aluminide phases on electrodeposited nanocrystalline nickel

“…However, experimental results of the present work and other investigations [17,18] indicate that a single layer of Al 3 Ni 2 is only formed on MC nickel. The reasons for the absence of all equilibrium intermediate phases could be: i) the resolution of used instruments is limited [19], ii) nucleation of certain phases is not possible due to insufficient activity of aluminum [20] and/or interfacial reaction barriers [21]. Jeske et al [22] investigated the formation of aluminide phases in Al/Ni couples with Atom probe field ion microscopy (very high resolution instrument) and detected only the Al 3 Ni 2 phase in the couples annealed at 350 C. Therefore the absence of other phases can be due to their inability for nucleation but they will certainly form if the aluminum activity at the coating surface is enough high and the surface condition is suitable to overcome the kinetics barriers of phase nucleation.…”

Application of artificial neural network for prediction of the oxidation behavior of aluminized nano-crystalline nickel

“…Among these, pack cementation is frequently used in practice, because it has the advantage of permitting effective plating of complicated shape structure with low cost and of being easy to carry out both in industrial processing and in the laboratory [12]. This method is essentially the static and in situ CVD process activated by decomposing halide salts such as NH 4 Cl.…”

“…Aluminide coatings may be applied through a variety of methods include: pack cementation, contactless gas-phase aluminizing (above the pack or out of pack, forced flow gas phase, low-pressure, vacuum pulse, cathodic arc physical vapor deposition, Arc-PVD, organometallic chemical vapor deposition, OM-CVD, and CVD in fluidized bed reactors, CVD-FBR), slurry aluminizing, hot-dipping in molten metals or fused salts, cladding by hot isostatic pressing (HIP), supersonic free-jet PVD, magnetron sputtering and plasma transferred arc (PTA) aluminizing [4,[8][9][10][11][12]. Among these, pack cementation is frequently used in practice, because it has the advantage of permitting effective plating of complicated shape structure with low cost and of being easy to carry out both in industrial processing and in the laboratory [12].…”

On the Influence of a Heat Treat for an Aluminizing Progress Based on Al Microparticles Slurry for Model Ni and Ni20Cr. Experimental and Theoretical Approaches.

“…Such environmentally friendly "slurry-related" alternatives are now under investigation within the framework of the European project "PARTICOAT" [8] to elaborate the aluminide layer combined with a ceramic thermally insulating top-coat onto Ni-based superalloys in a similar manner to the one described by Kolarik et al for austenitic stainless steels [9][10]. During the first step of the heat treatment, a Ni 2 Al 3 diffusion coating is obtained, which is typical of a high activity/low temperature process [11] and during the second step at higher temperature, a β-NiAl diffusion layer, a thin α-Al 2 O 3 bond coat and, on the top of it, a ceramic foam composed of hollow α-alumina sphere are realized.…”