Study of Molten Salt Corrosion of Superni-75 using Termogravimetric Technique

Abstract

The present study aims to evaluate the hot corrosion behaviour of the Ni-based alloy Superni- 75 in the molten salt environment of Na₂SO-60%V₂O₅ at 900°C under cyclic conditions. The thermogravimetric technique was used to establish the kinetics of corrosion. X-ray diffraction, scanning electron microscopy/energy-dispersive analysis and electron probe microanalysis techniques were used to analyse the corrosion products. Superni-75 has successfully provided the hot corrosion resistance to the given molten salt environment. The hot corrosion resistance of the Superni-75 has been attributed to the formation of uniform, homogeneous and adherent thick layer of the scale consisting mainly of oxides of nickel and chromium, and refractory Ni(VO₃)₂. These oxides and refractory nickel vanadates have blocked the penetration of oxygen and other corrosive species to the substrate.

Keywords: Hot corrosion, nickel-based alloy, superalloy, molten salt environment   

DOI: 10.3329/jname.v3i2.922

Journal of Naval Architecture and Marine Engineering 3(2006) 77-82