Electrochemical characterization of chromia- and alumina-forming nickel-based superalloys in molten silicates

Abstract

A comparison of the corrosion behaviour of simplified chromia- and alumina-forming alloys (Ni⿿30Cr and Ni⿿8Al⿿28Cr) in molten glass is performed via electrochemical methods. A pre-oxidation treatment in air prior to immersion ensured the formation of a 2-μm-thick oxide scale of Cr2O3 or Al2O3. The lifetime of Ni⿿30Cr depended on the competition between the oxide growth and its dissolution in the melt. For Ni⿿8Al⿿28Cr, the high solubility of alumina in the melt studied here led to severe aluminium loss in a few minutes and clearly demonstrated the higher efficiency of chromia-forming alloys for molten glass applications.