Electrochemical Corrosion Behavior of 12Cr1MoVG Steel for Superheater Pipe of Waste Incinerator in High Temperature Chloride-Sulfate Molten Salt System

Electrochemical corrosion behavior of 12Cr1MoVG steel for superheater pipe of waste incinerator in different molten salts at 850 ℃ was studied by electrochemical impedance spectroscopy. The surface morphology and cross-section morphology of 12Cr1MoVG steel were analyzed by scanning electron microscopy (SEM). The results indicate that the corrosion process of 12Cr1MoVG steel was controlled by the diffusion of oxidants in NaCl molten salt, the corrosion product scale was loose and porous, and the corrosion rate increased with the increase of corrosion time. The corrosion process of 12Cr1MoVG steel in NaCl+Na₂SO₄ molten salt was controlled by the migration of charged particles in oxide film, a protective scale with dense structure formed on the surface of 12Cr1MoVG steel, and the corrosion rate first increased and then decreased with the increase of corrosion time. The resistance of charge transfer reaction of 12Cr1MoVG steel in NaCl+Na₂SO₄ molten salt was much greater than that in NaCl molten salt. So the corrosion rate of 12Cr1MoVG steel in NaCl+Na₂SO₄ molten salt was obviously lower than that in NaCl molten salt.