Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : inconel alloy

Isothermal Oxidation of Simple and Pt-Modified Diffusion Coating on Inconel Alloy 600 In Water Vapor

Khalil; Al- Hatab; Al- Alqawie; Hussein; Ahmed Ali; Moosa

Engineering and Technology Journal, 2009, Volume 27, Issue 2, Pages 288-299

In this work the oxidation behavior of both inconel alloy 600 and coated system
(Pt-modified aluminide coating) was investigated in pure water vapor H2O in the
temperature range 700 - 900 ºC. The platinum was deposited by electrochemical
method. Pt-modified aluminide coating was applied to inconel alloy 600 by using singlestep
high activity pack cementation method. The weight gain measurements indicate
that the oxidation kinetic is parabolic for uncoated and coated alloy. At temperatures
below 900 ºC the inconel alloy 600 is less aggravated in water vapor environments
because it is a chromia former alloy. At 700 ºC, water vapor does not have a significant
effect on the spalling of oxide scales. At 900 ºC, water vapor causes spalling of the
oxide scales during isothermal oxidation of inconel alloy 600. Therefore, it is concluded
that this alloy should not be used above 900 ºC in water vapor environments. Large
voids were found at the oxide scales-substrate interface and at grains or at grain
boundaries due to the chromium outward diffusion toward the oxide scales.
At 900 ºC, the parabolic rate constant (kp) of the coated system was one order of
magnitude lower than that for the uncoated alloy. It was concluded that, water vapor
exhibit little effect on the Pt-modified aluminide coating. Oxide phases that formed on
coated system are: Al2O3, NiAl2O4, Cr2O3, and NiFe2O4.