The formation and dissolution of anodic oxide films on pure aluminium in alkaline solution

Coumarin as a green inhibitor of chloride-induced aluminum corrosion: theoretical calculation and experimental exploration

In the present work, the adsorption mechanism and corrosion inhibition effect of coumarin as a green inhibitor was characterized. Quantum chemical calculation and molecular dynamics simulation of the coumarin molecule were performed to get insight into the adsorption model by assessing the frontier orbital parameters and adsorption configuration. The theoretical calculation disclosed that coumarin exhibited a higher adsorption reactivity in the water phase than that in the gas phase, and the C[double bond, length as m-dash]O structure in coumarin was the most favorable site for adsorption occurring. Coumarin could adsorb spontaneously on an aluminum surface in a parallel manner, where electron donation occurred from the aluminum surface to the inhibitor. Additionally, the experimental investigation determined that coumarin decreased the aluminum dissolution by suppressing both the anodic and cathodic reactions. The optimal coumarin concentration of 0.5 wt% resulted in a maximum inhibition efficiency (89.6%), but coumarin at a higher concentration would lead to the competitive and unstable adsorption of inhibitor molecules, thus decreasing the inhibition effect. Moreover, surface chemical characterization confirmed the formation of Al-coumarin complexes, which was in accordance with the theoretical calculation.

Improvement of Aluminum-Air Battery Performances by the Application of Flax Straw Extract

The effect of a flax straw extract on Al corrosion inhibition in a strong alkaline solution was studied by using electrochemical measurements, weight-loss analysis, SEM, and FTIR spectroscopy. Flax straw extract added (3 vol %) to the 5 m KOH solution to act as a mixed-type Al corrosion inhibitor. The electrochemistry of Al in the presence of a flax straw extract in the alkaline solution, the effect of the extract on the Al morphology and surface films formed, and the corrosion inhibition mechanism are discussed. Finally, the Al-air battery discharge capacity recorded from a cell that used the flax straw extract in the alkaline electrolyte is substantially higher than that with only a pure alkaline electrolyte. This improved sustainability of the Al anode is attributed to Al corrosion inhibition and, consequently, to hydrogen evolution suppression.

Corrosion of aluminium alloy 1100 in post-LOCA solutions of a nuclear reactor

The influence of pH and temperature on aluminium corrosion in post-LOCA solutions was investigated and the role of adsorbed boron was discussed.

Progress in Nano-Engineered Anodic Aluminum Oxide Membrane Development

The anodization of aluminum is an electro-chemical process that changes the surface chemistry of the metal, via oxidation, to produce an anodic oxide layer. During this process a self organized, highly ordered array of cylindrical shaped pores can be produced with controllable pore diameters, periodicity and density distribution. This enables anodic aluminum oxide (AAO) membranes to be used as templates in a variety of nanotechnology applications without the need for expensive lithographical techniques. This review article is an overview of the current state of research on AAO membranes and the various applications of nanotechnology that use them in the manufacture of nano-materials and devices or incorporate them into specific applications such as biological/chemical sensors, nano-electronic devices, filter membranes and medical scaffolds for tissue engineering.

Uniform and Pitting Corrosion Processes of Al, Al-6061, Al-Zn and Al-Cu Alloys Exposed to SCN- Solutions and the Effect of Some Inorganic Anions

The effect of the alloying elements and some inorganic inhibitors (WO4 2-, MoO4 2-, SiO3 2- and CrO4 2- anions) on the uniform and pitting corrosion characteristics of Al-6061, Al-4.5% Cu, Al-7.5% Cu, Al-6% Zn and Al-12% Zn alloys were studied in 0.04M KSCN solution. Susceptibility of the tested alloys towards pitting corrosion was investigated using transient (potentiostatic and galvanostatic) measurements. An independent method of chemical analysis, namely ICP-AES (inductively coupled plasma atomic emission spectroscopy) was also used to study the effect of the alloying elements and the tested inorganic anions on the uniform corrosion of these materials. Results obtained were compared with pure Al. ICP measurements revealed that the alloyed Cu and alloyed Zn enhance uniform corrosion of the Al samples, while WO4 2-, MoO4 2-, SiO3 2- and CrO4 2- anions suppressed it. Transient measurements showed that nucleation of pit takes place after an incubation time (t i). The rate of pit initiation and growth (t i -1 ) increased with increase in SCN- concentration, applied anodic current, applied anodic potential and solution temperature. This rate of pit initiation and growth decreased in presence of inorganic inhibitors to an extent depending on the concentration and type of the introduced inhibitor. Alloyed Zn was found to accelerate pitting attack, while alloyed Cu suppressed it. Among the tested Al alloys, Al-6061 presented the highest resistance towards uniform and pitting corrosion processes. SiO3 2- and CrO4 2- were the most efficient anions in inhibiting uniform and pitting corrosion processes of Al in these solutions.