Analysis of the Ce(III) chloride, Ce(III) nitrate, and Ce(III) propionate as corrosion inhibitor of the aluminum alloys in NaCl solution

Abstract

Green corrosion inhibitors, Ce(III) chloride, Ce(III) nitrate, and Ce(III) propionate, were tested in NaCl solution with the aim to evaluate their inhibitory effect on 7049 aluminum alloy and to propose a mechanism of their inhibitive action. Corrosion properties of the formed inhibitor layer were analyzed using electrochemical impedance spectroscopy, while the pit formation resistance was analyzed using potentiodynamic polarization tests. Morphology of the formed pits was evaluated by scanning electron microscope/energy‐dispersive spectroscopy analysis. It was shown that Ce(III) propionate in NaCl solution has a noticeably higher protective ability than Ce(III) chloride and Ce(III) nitrate. The presence of cerium, propionate anions, and Al–O bonds in the inhibitive layer on the 7049 aluminum alloy surface was confirmed by X‐ray photoelectron spectroscopy analysis. This indicates the formation of Ce propionate complexes and bonds via oxygen atoms from carboxylate anions with the metal surface. Density‐functional theory methods were used for the geometry optimization of possible Ce propionate complexes as corrosion inhibitors.

Cerium lactate as green corrosion inhibitor of AA2024 alloy

“…In the high‐resolution XPS spectra of Al 2p (Figure 10a), two peaks appeared at a binding energy of 70.9 and 74.2 eV. These peaks are characteristic of the metallic Al (Al matrix), [ 22,44,45 ] and a thin film of the oxidized Al (Al oxides/hydroxides), respectively. [ 30,45,46 ]…”

“…These peaks are characteristic of the metallic Al (Al matrix), [ 22,44,45 ] and a thin film of the oxidized Al (Al oxides/hydroxides), respectively. [ 30,45,46 ]…”

“…In the high-resolution XPS spectra of Al 2p (Figure 10a), two peaks appeared at a binding energy of 70.9 and 74.2 eV. These peaks are characteristic of the metallic Al (Al matrix), [22,44,45] and a thin film of the oxidized Al (Al oxides/hydroxides), respectively. [30,45,46] The XPS C 1s high-resolution spectrum (Figure 10b) consists of four peaks located at binding energies of 284.8, 286.2, 287.1, and 288.9 eV.…”

“…These peaks are characteristic of the metallic Al (Al matrix), [22,44,45] and a thin film of the oxidized Al (Al oxides/hydroxides), respectively. [30,45,46] The XPS C 1s high-resolution spectrum (Figure 10b) consists of four peaks located at binding energies of 284.8, 286.2, 287.1, and 288.9 eV. Peaks at these energies indicate the adsorption of functional groups C-C/C-H, C-OH, C═O, and O-C═O, respectively, from the organic ligand (lactate) on the surface of the AA2024 aluminum alloy.…”

Cerium and aluminum molybdates as inhibitors of the aluminum AA1050 corrosion process in aqueous NaCl solutions

“…Ce(III) oxides and hydroxides also precipitates, in a lower extent, over all the aluminum matrix. [41] The inhibitory properties of Al(III) are also attributed to its reaction with the OH − ions generated at the cathodic sites, causing the precipitation of aluminum hydroxides or oxyhydroxides. [12,13] For each curve in Figure 4, the corrosion potential (Ec), the corrosion current density (Ic), and the cathodic and anodic slopes were calculated.…”