https://cyberleninka.org/article/n/1309372.pdf

Corrosion-resistant metallic coatings

The chemical and electrochemical behavior of titanium was examined in the Lewis acidic aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl 3 -EtMeImCl, molten salt at 353.2 K. Dissolved Ti(II), as TiCl 2 , was stable in the 66.7-33.3% mole fraction ( m/o composition of this melt. but slowly disproportionated in the 60.0-40.0 m/o melt. At low current densities, the anodic oxidation of Ti(0)did not lead to dissolved Ti (II). but to an insoluble passivating film of TiCl 3 . At high current densities or very positive potentials, Ti (0) was oxidized directly to Ti(IV); however, the electrogenerated Ti (IV) vaporized from the melt as TiCl 4 (g). As found by other researchers working in Lewis acidic AlCl 3 -NaCl, Ti(II) tended to form polymers as its concentration in the AlCl 3 - EtMeImCl melt was increased. The electrodeposition of Al-Ti alloys was investigated at Cu rotating disk and wire electrodes. Al-Ti alloys containing up to ∼19% atomic fraction (a/o) titanium could be electrodeposited from saturated solutions of Ti (II) in the 66.7-33.3 m/o melt at low current densities, but the titanium content of these alloys decreased as the reduction current density was increased. The pitting potentials of these electrodeposited Al-Ti alloys exhibited a positive shift with increasing titanium content comparable to that observed for alloys prepared by sputter deposition.

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Electrochemistry of Titanium and the Electrodeposition of Al-Ti Alloys in the Lewis Acidic Aluminum Chloride–1-Ethyl-3-methylimidazolium Chloride Melt

The effect of sodium molybdate on the pitting corrosion of aluminum

The electrochemistry of Zr(IV) and Zr(II) and the electrodeposition of Al-Zr alloys were examined in the Lewis acidic 66.7-33.3 mol % aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt at 353 K. The electrochemical reduction of Zr(lV) to Zr(II) is complicated by the precipitation of ZrCl 3 ; however, solutions of Zr(II) can be prepared by reducing Zr(IV) with Al wire. Al-Zr alloys can be electrodeposited from plating baths containing either Zr(IV) or Zr(II), but for a given concentration and current density, baths containing Zr(IV) lead to Al-Zr alloys with the higher Zr content. This result was traced to the diminutive concentration-dependent diffusion coefficient for Zr(II). It was possible to prepare Al-Zr alloys containing up to ∼17% atomic fraction (atom %) Zr. The structure of these deposits depended on the Zr content. Alloys containing less than 5 atom % Zr could be indexed to a disordered face-centered cubic structure similar to pure Al, whereas alloys containing ∼17 atom % Zr were completely amorphous (metallic glass). The chloride pitting potentials of alloys with more than 8 atom % Zr were approximately +0.3 V relative to pure Al.

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Electrodeposition of Al-Mo Alloys from the Lewis Acidic Aluminum Chloride-1-ethyl-3-methylimidazolium Chloride Molten Salt

Characterisation and corrosion protection properties of polypyrrole electropolymerised onto aluminium in the presence of molybdate and nitrate

The electrochemical response of Al alloys containing various concentrations of Mo in solid solution was studied using potentiodynamic polarization. The evolution of the chemical composition of the passive film during exposure to deaerated O.1N KCl was analyzed using x-ray photoelectron spectroscopy. Exposure of Al-Mo alloys to the chloride solution results in an increase in the corrosion potential and a decrease in the cathodic Tafel slope. The breakdown potential is also found to increase with higher concentrations of Mo in the alloy. These results correlate with an increase in the amount of Mo in the oxide film during polarization, even though the concentration of Mo in the passive film is well below that in the alloy. This work suggests that the oxidized Mo in the passive film inhibits the nucleation of pits in the alloy by improving the integrity of the passive film.

Corrosion Behavior of Aluminum‐Molybdenum Alloys in Chloride Solutions

En alliant Mo et Al en solution solide, on ameliore considerablement la resistance a l'attaque localisee en deplacant la courbe de polarisation anodique dans la direction noble. L'alliage Al-6Mo resiste a la corrosion par piqure dans des solutions contenant du chlorure saturees en air

Influence of Molybdenum on the Pitting Corrosion of Aluminum Films

The composition and thickness of the oxide/hydroxide film that forms on pure Al polarized in 0.05M Na2SO4 solutions with and without the addition of 1000 ppm Cl− under acidic, near‐neutral, and alkaline conditions have been determined using x‐ray photoelectron spectroscopy. Changes in the films due to the ex situ nature of the measurements have also been characterized. The results were plotted on surface behavior diagrams to follow the evolution of the surface during polarization and compared with the results predicted by the Pourbaix diagram. Although Al(OH)3 is the most stable species to form in near‐neutral solutions under equilibrium conditions, the composition of the film at the corrosion potential under our experimental conditions was found to be that of the oxyhydroxide AlOOH at each pH. In the pH 7 and pH 10 solutions, this film thickens during anodic polarization (up to the pitting potential for the Cl−‐containing solutions), but the composition is unchanged. In contrast, the Cl−‐free, pH 2 solut...

H. F. Hough

Papers

Corrosion Behavior of Aluminum‐Molybdenum Alloys in Chloride Solutions

Influence of Molybdenum on the Pitting Corrosion of Aluminum Films

Corrosion/passivation of aluminum in dilute sulfate solutions: A comparison of Pourbaix and surface behavior diagrams

Influence of Molybdenum on the Pitting Corrosion of Aluminum Films.

The Corrosion Behavior of Aluminum-Molybdenum Alloys in Chloride Solutions