Isothermal oxidation of simple and pt-modified diffusion coating on inconel alloy 600 in water vapor

Abstract EN

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 ?C.

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 ?C the inconel alloy 600 is less aggravated in water vapor environments because it is a chromia former alloy.

At 700 ?C, water vapor does not have a significant effect on the spalling of oxide scales.

At 900 ?C, 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 ?C 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 ?C, 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.

Keywords: Oxidation, pack cementation, super alloy, coating, inconel alloy.-