The effects of chloride ions and magnetite on the corrosion of Alloy 690 were investigated using electrochemical techniques in deaerated alkaline solutions at 60°C. Independently, the effect of chloride ions and galvanic coupling to magnetite produce a small influence on the corrosion rate of Alloy 690. However, the anodic dissolution rate of Alloy 690 is drastically accelerated when the effects of chloride ions and magnetite are combined. This acceleration is because the coupled potential between Alloy 690 and magnetite is shifted from the stable passive region of Alloy 690 to the active-passive transition region by the addition of 1 M NaCl.

Subject
Substrates, Corrosion rate, Nickel based alloys, Tubes, Sodium chloride, Chloride ions, Alkaline solutions, Steam generators, Sodium chloride solution, Anodic dissolution, Magnetite, Alloys, Galvanic corrosion
Keywords:
galvanic corrosion, magnetite, nickel alloys, sodium chloride, steam generator
© 2017, NACE International
2017
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