Influence of Praseodymium/Synergistic Corrosion Inhibition in Mixed Rare-Earth Diphenyl Phosphate Systems

摘要

Mixed rare-earth organophosphates have been investigated as potential corrosion inhibitors for. AA2024-T3, and previously have shown synergistic inhibition behavior; however, the mechanism was not identified. In this paper, a key factor contributing to corrosion inhibition of AA2024-T3 with mischmetal diphenyl phosphate [Mm(dpp)_3] is the unique stability of Pr(dpp)_3 compared to other key rare earths in mischmetal. Although increasing pH causes precipitation of other components, the Pr compound is stable at higher pH. Electrochemically, a synergy is evident when Ce(dpp)_3 and Pr(dpp)_3 are combined. Raman mapping indicates the Pr(dpp)_3 inhibitor leads to a more uniform coverage of the alloy.