Solution Transformation of the Products of AC Electrochemical Metal Oxidation

Abstract

Electrochemical oxidation of copper and aluminium using alternating current of industrial frequency results in the formation of non-equilibrium products. Their transformations during the ageing in sodium chloride solutions of different concentrations have been considered. According to X-Ray diffraction confirmed by TG/DSC/DTG analysis, irrespective of solution concentration, the ageing products consist of aluminium oxyhydroxide (boehmite, AlOOH), copper-aluminium carbonate hydroxide hydrate (Cu-Al/LDH) and copper chloride hydroxide (Cu[2](OH)[3]Cl). The increase of the solution concentration leads to Cu[2](OH)[3]Cl formation and makes difficulties for metal oxide carbonization to Cu-Al/LDH. Ageing in highly diluted solution contributes not only to Cu-Al/LDH formation but also boehmite hydration that is verified by IR-spectra. The pore structure characteristics have been also discussed. They do not significantly depend on phase composition and vary in ranges of 161.2-172.6 m{2}/g (specific surface areas), 0.459-0.535 cm{2}/g (total pore volumes). Pore size distributions reveal that a pore structure is predominantly formed by pore with the sizes from 3 to 22°nm; 3.6°nm is the size of pores with the largest pore volume

Development of Hybrid Sol-Gel Coatings on AA2024-T3 with Environmentally Benign Corrosion Inhibitors

“…Additional peaks are characteristic of the confirmation of CH2 at 1460 cm -1 and 1300 cm -1 . As expected The carbonyl function C=O is shows by a peak at 1707 cm -1 [142], [145], [147]. Sol-gel coating was 101° ± 2.…”

“…Although there was a trace of adsorption of Benzimidazole after 144hr of immersion, hydration taking place due to diffusion action, and as a result of this OH-stretching appears at low intensity in the region between 3000 and 3400 cm -1 attributed to aluminium hydroxide Al-OH film and the remained propagated H2O in the interfacial and oxidised layer [142], [147], [148].…”

“…After applying the coating this peak at 1710 cm -1 started to decrease in intensity, and after 144 hrs of immersion started to disappear, replaced with a new peak at 1585 cm -1 representing Al-O-C group-specific vibrations. Besides, the C=C band is characterized by a small peak group in 3007 cm -1 [142], [147]- [149]. The EIS data analysis found that the BZI and OA-BZI treatments were capable of providing moderate corrosion protection to the AA2024 substrate, even after 144 hrs immersion.…”

“…are respectively assigned to asymmetric and symmetric (δ Al-OH), bending vibrations of loose O-H of which related to boehmite γ-AlO (OH), the band peaks at 880 cm -1 is assigned to raised peak stretch of O-H (δ OH). The raised peaks of the groups 740 and 650 cm-1 are respectively assigned to vibrations and stretching of symmetric and asymmetric of aluminium-oxygen (δ Al-O)[142].…”

Study of Kinetics of Copper Oxidation by Electrolysis Under Non-Stationary Conditions

“…The research to date states that the transition from direct current to alternating current of various forms (pulsating, asymmetric, pulsed), including those with an adjustable component, favourably affects the synthesis of new compounds [7][8][9][10].…”