Gas phase aluminizing of nickel alloys with hydrogen chloride

Kohlscheen, J.; Stock, H.‐R.

doi:10.1016/j.surfcoat.2007.07.003

Cited by 28 publications

(20 citation statements)

References 11 publications

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“…In addition to these, a mixed zone (MZ) was identified in the present research work (see scheme in Fig.1b) as the layer where these particles appear together with substrate phases (γ and γ'). The additional third layer was differently considered in literature: sometimes it was omitted, including it into IDZ or into substrate [6,4,11], sometimes it was widened to include the whole Al-enriched substrate layer [11] and in other cases it was considered as a secondary reaction zone [8].…”

Section: Resultsmentioning

confidence: 99%

Evolution of the Diffusion Layer in a CMSX4 Single Crystal Superalloy

Gariboldi

Han

Longo³

et al. 2011

AMR

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Aluminising processes are well-known techniques industrially adopted to enrich of aluminium the surface layers of Ni-based alloys thus improving their resistance to environmental interaction at high-temperature. The results of aluminising processes are typically described in terms of the presence, compositions and thickness of the sequence of layers at the surface of the treated parts. Following this approach, the microstructural features of the diffusion layers obtained under different holding times via vapour-phase type high-temperature low-activity process were experimentally investigated on single crystal CMSX4 alloy. The attention was particularly focused on the effect of the crystallographic orientation of the crystal on the coating features. The evolution of the diffusion layers under different process conditions was then taken into account.

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Section: Resultsmentioning

confidence: 99%

Evolution of the Diffusion Layer in a CMSX4 Single Crystal Superalloy

Gariboldi

Han

Longo³

et al. 2011

AMR

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“…Aluminizing processes include a range of industrial techniques aimed at enriching in aluminum the surface of Ni-based alloys, thus improving their resistance to environmental high temperature interactions [1][2][3][4]. Their modelling can help carrying out industrial aluminizing processes by predicting the coating features under specific process routes.…”

Section: Introductionmentioning

confidence: 99%

“…Essential steps for developing a good physically-based model of a process are a correct description of the involved phenomena (leading not only to valid equations, but also to a clear identification of the key material and process parameters) and the availability of careful description of process results, useful for either validating the model or calibrating some parameters to specific cases. The description of diffusion-controlled processes, such as aluminizing, is typically quantified in terms of the composition and thickness of the sequence of the resulting surface diffusion layers [4][5][6], sometimes completed by the weight gain and/or by the final position of phase interfaces. The solid phases to be taken into account for Al-enrichment process of Ni or Ni-base alloys at the relatively high process temperatures can be found in the Al-Ni phase diagram (such as that given in Fig.1a): solid solution of Al in Ni (Ni), Ni 3 Al, NiAl and Al 3 Ni 2 .…”

Section: Introductionmentioning

confidence: 99%

Modelling of Phase Evolution during Aluminizing Processes

Gariboldi

Verani

Riva

2011

AMR

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Abstract. Aluminizing processes are a well-known set of techniques industrially adopted to enrich in aluminum the surface layers of Ni-based alloys, thus improving their resistance to environmental interactions at high temperature. The results of aluminizing are described in terms of the presence, compositions and thickness of the sequence of the resulting surface diffusion layers. A combination of difficulties arising both from the mathematical and the material side restricted the number of available user-friendly models and their applicability to specific alloys or process conditions. The aim of the research work here presented is to overcome part of these difficulties. A synthesis of some well-established models was implemented in a robust numerical algorithm, that automatically prevents instabilities and convergence problems. Such numerical algorithm has been experimentally validated by comparing the results to the experimentally measured composition of profiles obtained for a set of vapor-phase aluminized samples of commercially pure Ni. The model was then applied to predict the effects of the process temperature and of the chemical composition of the surface.

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“…Aluminizing is one of the best methods available for improving oxidation and corrosion resistance of nickel base alloys. This is an application requirement for high temperature components such as turbine blades [2]. At high temperatures, Al in the surface of a coated substrate can be oxidized preferentially and forms a thin and dense alumina layer.…”

Section: Introductionmentioning

confidence: 99%

“…At high temperatures, Al in the surface of a coated substrate can be oxidized preferentially and forms a thin and dense alumina layer. This layer acts as a diffusion barrier and substantially reduces the oxidation rate of the substrate [2][3][4].…”

Section: Introductionmentioning

confidence: 99%