The deleterious effects of corrosion can be mitigated by the application of coatings that can form a protective oxide layer. Halide Activated Pack Cementation (HAPC) is one such coating method in which a halide vapor is generated within a pack and undergoes reactions that ultimately result in the coating element, e.g., Al, being deposited and diffused into the substrate. In this study, the solid state diffusion of aluminum into stainless steel substrates was modeled using a popular computing environment.

UNS S30400 austenitic stainless steel was aluminized for various times at 850°C. Samples were cross-sectioned for analysis by optical microscopy and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS).The coating thickness for each layer was measured and concentration profiles were determined. The Boltzmann-Matano method was applied to each concentration profile to determine the diffusion coefficients of aluminum in the coating and substrate phases assuming a semi-infinite substrate. This model can be utilized to predict coating thickness, the aluminum concentration profile and phases in the coating at 850°C as a function of time.

Subject
Nickel coatings, Coatings, Diffusion layers, Substrates, Diffusion, Aluminum, Substrate surfaces, Coating thickness, Interfaces, Kinetics, Aluminides, Stainless steel, Activators
Keywords:
Stainless steel, pack aluminizing, halide activated pack cementation, HAPC, aluminum chloride, aluminide coating, diffusion, modeling, Fick’s second law
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2016
Association for Materials Protection and Performance (AMPP)
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