Influence of gaseous atmosphere on electrochemical behavior of nickel alloys in LiCl-KCl-Na₂SO₄ at 700 °C

Electrochemical behavior of Ni alloys (Ni, β-NiAl, β-NiAl/Cr) was investigated in LiCl-KCl-Na₂SO₄ electrolyte at 700 °C under three gaseous atmospheres (Ar, O₂, O₂-0.1%SO₂). In oxidizing atmospheres, Ni rapidly degraded due to instability of NiO, and alumina-rich scale on β-NiAl provided limited protection against hot corrosion (e.g., cracks in the scale under O₂-0.1%SO₂); however, the addition of both Al and Cr resulted in enhanced corrosion resistance by forming a mixed-oxide (Al₂O₃-Cr₂O₃) scale in oxidizing atmospheres. In hot corrosion processes of Ni alloys, the formation and stability of oxide scales in the molten salt were influenced by gaseous atmosphere and alloying elements.