Kinetics of phase layer growth during aluminide coating of nickel

Hickl, Anthony J.; Heckel, R. W.

doi:10.1007/bf02658400

Cited by 147 publications

(50 citation statements)

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“…Compared to the other methods mentioned above, the two-step process can aluminize at low temperature by pack aluminization of preliminarily nickel-coated samples [9]. Due to the simple composition and single structure of the nickel layer, the Ni/Al diffusion coefficient is higher than that of a superalloy [11].…”

Section: Introductionmentioning

confidence: 99%

Composition Distribution and Electrochemical Behavior of an Ni2Al3 Coating on Q235 Steel

Wang

Zheng

et al. 2016

Metals

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An Ni 2 Al 3 coating was prepared via the electrodeposition of nickel followed by pack aluminization. Polarization curve and electrochemical impedance spectroscopy were performed to study the room temperature corrosion behavior of the coating in a 3.5 wt. % NaCl solution. The long-term impedance of the coating was also investigated after immersion for 30 days. Results show that the Ni 2 Al 3 coating possessed lower corrosion current density (I corr ) and higher polarization resistance (R p ) than the substrate in the solution. The Bode plots of the coating showed two time constants after the long-term immersion. Pitting corrosion was found on the coating surface.

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Section: Introductionmentioning

confidence: 99%

Composition Distribution and Electrochemical Behavior of an Ni2Al3 Coating on Q235 Steel

Wang

Zheng

et al. 2016

Metals

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“…Let us briefly describe the HH model [1], developed for the case of a semi-infinite medium. For simplicity reasons the names attributed by Hickl and Heckel to phases are here used (see Figure 1), even if some of the phases are currently referred in a different way and, more often, they are described in terms of their chemical composition.…”

Section: Mathematical Model and Numerical Discretizationmentioning

confidence: 99%

“…The model was tested using both material data and initial/boundary conditions of [1,11] and comparing the obtained results to those presented in the papers. The stability of the model and of its space or time adjustment rules were tested by modeling the case of a first step in a two-phase lowtemperature and high-activity aluminizing process, being it relatively complex from the mathematical point of view (Fig.…”

Section: Experimental Validation Of the Modelmentioning

confidence: 99%

“…In such processes, under equilibrium conditions, the activity of Al on the coating surface equals that of the Al-source material [3][4][8][9][10]. It was also demonstrated that, at a given temperature, the surface composition of the component is related to that of the Al-source and that it can be considered as constant with time [1,7,10]. For the above reasons, the key process parameters to be taken into account for process control or modeling are the time and the temperature at which the aluminizing occurs (the latter typically kept constant during the process).…”

Section: Introductionmentioning

confidence: 99%

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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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“…If the interdiffusion coefficients D i do not vary with composition, then analytical solutions are known (7,8) for the composition profile in each phase, for instance the solution for the phase j is:…”

Section: Rffrodu Ict T Ity Of Thementioning

confidence: 99%