USA Type 304 stainless steel coupons were aluminized at 650, 750 and 850°C for coating times in the 1-25 hour range via halide activated pack cementation. Mass gains per unit area and coating thicknesses were plotted as a function of time. Empirical rate equations and the corresponding parabolic rate constants were obtained for the kinetics of aluminization for these two metrics, i.e., mass change and thickness of coating. The Vickers micro-hardness values of the coated regions ranged between 700-1114 HV. Coating surface phases were identified using X-ray diffraction analysis as Al5FeNi, Al5Fe, Al86Fe14 and AlFe with one or more absent depending upon coating temperatures and times. Scanning electron microscopy coupled with energy dispersive spectroscopy was utilized to obtain diffusion profiles for aluminum, chromium, nickel and iron.

Subject
Scanning electron microscopy, X-ray diffraction, Coatings, Substrates, Metal surfaces, Aluminum, Constants, Coating thickness, Mass gain, Aluminides, Surface profile, Stainless steel, Aluminum alloys
Keywords:
coatings, pack cementation, aluminizing, stainless steel, high temperature corrosion
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2013
Association for Materials Protection and Performance (AMPP)
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