Anti-corrosion protection of aluminium alloy by zeolite doped with zinc, calcium and manganese cations

• I.М. Zin, S.А. Korniy, M.-O.М. Danyliak, O.P. Khlopyk and M.Ya. Holovchuk

Karpenko Physico-Mechanical Institute of National Academy of Science of Ukraine, Naukova str., 5, 79060, Lviv, Ukraine

Abstract: Ecologically safe anti-corrosion pigments based on synthetic zeolite Na-A modified with zinc, calcium and manganese were synthesized using liquid-phase ion exchange. The dispersion of the modified zeolites, their initial chemical composition and changes upon exposure to 0.1% sodium chloride solution were studied by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). The corrosion resistance of aluminum alloy D16T in 0.1% NaCl solution and in inhibited solutions containing modified zeolites was studied using the methods of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). It was revealed that the use of modified zeolites increases the corrosion resistance of aluminum alloy in the corrosive solution by 2–9 times depending on their concentration and type of metal cation. Electrochemical impedance spectroscopy showed that the presence of modified Zn-zeolite at a concentration of 2 g/l in the corrosive solution increases the charge transfer resistance of the sample of aluminum alloy by about 5 times. The greatest anti-corrosion effect on the aluminum alloy is provided by the zeolite modified with Zn²⁺, while the smallest, by the zeolite modified with Ca²⁺, due to the different ability of these divalent cations to desorb from the zeolite into the corrosive environment. It was found that the anticorrosive effect on the aluminum alloy D16T in an inhibited solution with Zn-zeolite is due to the formation of continuous oxide-hydroxide layers in the vicinity of intermetallic inclusions on its surface. The chemical analysis of modified zeolites after 96 h of exposure to aluminum alloy D16T in solutions with a concentration of 2 g/l confirms the preservation of the aluminosilicate skeleton of zeolite and indicates slow ion exchange of divalent cations of calcium, zinc and manganese for sodium cations from corrosion solution. The obtained modified zeolites have the potential to be used for the development of “smart coating” technologies for corrosion protection of aluminum alloys.

Int. J. Corros. Scale Inhib., 2021, 10, no. 4, 1715-1728
doi: 10.17675/2305-6894-2021-10-4-22

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