Corrosion behavior of 8090-T851 alloy in HCl solution containing metal cations

General corrosion of 8090-T851 Al-Li alloy in a pH = 2.0 HCl solution was studied by weight loss and polarization techniques in the presence of $Cu^{2+}$, $Al^{3+}$, and $Li^{+}$. $Cu^{2+}$ exerted the largest effect as corrosion activators followed by $Al^{3+}$, whereas $Li^{+}$ ions showed little effect. The extent of acceleration of corrosion is a function of ion concentration in solution and seems to depend on the ability of cations to deposit on the corroding substrate and/or activation of the metal surface owing to a change in its nature in the presence of cations

The role of metal cations on the corrosion behaviour of 8090-T851 alloy in pH 2.0 solution

The influence of cations such as $Cu^{2+}, AI^{3+}$ and $Li^+$ on the corrosion behaviour of 8090-T851(AI-Li) alloy in a pH 2.0 HCI solution was investigated by weight loss and polarization techniques. Weight los s experiments showed that the effect of cation is a strong function of its nature and concentration and the effect became significant only above a critical concentration. Of the cations studied, $Cu^{2+}$ ions were found to be the most aggressive corrosion activators followed by $Al^{3+}$ ions while $Li^+$ ions showed little effect. Polarisation experiments inferred that $Cu^{2+}$ ions influence the corrosion process mainly by accelerating the cathodic reaction. While a decrease in both cathodic and anodic reactions was evident in the presence of $Al^{3+}$ ions at higher concentration, $Li^+$ ions showed no remarkable affect either on cathodic or anodic reactions. Critical analyses of results of the two experiments indicated that the corrosion activation by $Al^{3+}$ ions is due to their chemical reactivity with the corroding substrate. Little enhancement in corrosion by $Li^+$ ions is attributed to the increase in solution conductivity in their presence

Corrosion behaviour of 8090-T851 Al-Li alloy and aluminium in pH 2 solution containing cupric ions

Weight loss studies and scanning electron microscopy revealed that cupric ions act as accelerators of the corrosion of aluminium and an Al-Li alloy in chloride solution with a pH of 2. The corrosion rates of the two materials increased with cupric ion concentration in the solution and drastically so when this exceeded a critical value. The nature of the corrosion was significantly influenced by the presence of cupric ions, changing from a general to a mixed mode of corrosion for aluminium, while the alloy exhibited localised attack as the predominant mode of corrosion in the presence of cupric ions. The severity of localised attack increased with increasing cupric ion concentration in both cases. Possible mechanisms by which the cupric ions accelerate the corrosion reaction are highlighted