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International Journal of Physical Sciences Vol. 1 (1), pp.
027-033, September 2006
© 2006 Academic Journals
Full Length Research Paper
Cyclic oxidation behavior
of Ni- and Fe-based superalloys in air and Na2SO4-25%NaCl
molten salt environment at 800 oC
T.S. Sidhu*, Ajay Malik, S. Prakash,
R.D. Agrawal
Metallurgical and Materials Engineering Department,
Indian Institute of Technology Roorkee, Roorkee-247667 (UA) India
*Corresponding authors E-mail:
tssidhu@rediffmail.com, Phone: 09412968912; Fax: 01332-285243.
Accepted 20 September 2006 |
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The present investigation aims to evaluate the
high-temperature oxidation and hot corrosion behaviour of Ni-based
superalloy (Superni 75) and Fe-based superalloy (Superfer 800H). The
superalloy specimens were exposed to air and molten salt (Na2SO4-25%NaCl)
environment at 800 °C under cyclic conditions. The thermogravimetric
technique was used to establish the kinetics of corrosion. X-ray
diffraction (XRD), scanning electron microscopy (SEM) and electron probe
micro analyser (EPMA) techniques were used to characterize the corrosion
products. The hot corrosion resistance of Ni-based superalloys was found
to be better than that of Fe-based superalloys. The formation of scale
rich in Cr2O3, NiO and spinel NiCr2O4
has contributed for the better oxidation and hot corrosion
resistance of Superni 75, whereas relatively lesser hot corrosion
resistance of Superfer 800H is due to the formation of non-protective
oxide of iron, and sulphides of iron and nickel.
Key Words: Superalloys, Hot corrosion, Oxidation, Molten salt
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