Electrochemical Noise Evaluation on Superalloys Inconel 690, Incoloy 800, Waspaloy and Ultimet

Superalloys are based on elements as iron, cobalt and nickel, the main application of superalloys is in hottest section of turborreactors, nuclear reactors, petrochemical equipment, turbochargers and rockets. The main purpose of this research is analyze the behavior to corrosion of each superalloy when those are exposed to aggressive electrolyte present on environment. Superalloys evaluated in two environments was Inconel 690, Incoloy 800, Waspaloy and Ultimet, at 0.5M of H₂SO₄ and NaCl at 3.5%, using temperatures of 25 and 60°C. Electrolytes was used because of they are present in the environment as acid rain and marine atmosphere. This work shows a study of corrosion resistance using electrochemical noise technique, current density corrosion and superalloys corrosion mechanism. Results show that sulfuric acid is the most aggressive electrolyte for these superalloys at both temperatures and the mechanism predominant in this superalloy is localized corrosion.