Corrosion Inhibition of Pure Aluminum by Morpholine-Methylene-Phosphonic Acid in Neutral Chloride Solution

Abstract The corrosion inhibition of pure aluminum by morpholine-methylene-phosphonic acid (MMPA) in near-neutral aqueous chloride solutions was investigated using direct current and alternating current techniques. The inhibition efficiency, P, was ∼ 97% at a concentration of 10−4 M MMPA. The adsorption of MMPA on aluminum oxide (Al2O3) prevents the adsorption of chloride ions and leads to the formation of an insoluble aluminum complex of MMPA, which explains the significant decrease of the aluminum dissolution rate in the aggressive medium.