Surface and corrosion properties of AA6063-T5 aluminum alloy in molybdate-containing sodium chloride solutions
D. S. Kharitonov, Illia Dobryden, Birhan Sefer, Jacek Ryl, Angelika Wrzesińska, И. В. Макарова, Izabela Bobowska, И. И. Курило, Per M. Claesson
Abstract
Corrosion properties of aluminum alloy AA6063-T5 were investigated in molybdate-containing NaCl solutions. Electrochemical, microscopic, and spectroscopic experiments were utilized to examine the mechanism of corrosion inhibition by molybdates. SEM-EDX, magnetic force, and intermodulation electrostatic force microscopy data suggested that the inhibition initiation preferentially occurred over Fe-rich cathodic IMPs. Spectroscopic measurements demonstrated that the formed surface layer consists of mixed Mo(VI, V, IV) species. This layer provided inhibition with an efficiency of ∼90% after 4 h of exposure. High efficacy of ∼70% was achieved even after one week of exposure. A two-step oxidation-reduction mechanism of corrosion inhibition by aqueous molybdates was proposed.