International Journal of
Physical Sciences

  • Abbreviation: Int. J. Phys. Sci.
  • Language: English
  • ISSN: 1992-1950
  • DOI: 10.5897/IJPS
  • Start Year: 2006
  • Published Articles: 2537

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
Email: [email protected]

  •  Accepted: 20 September 2006
  •  Published: 30 September 2006

Abstract

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  NiCr2O 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 environment