Abstract:Anodisation is essential for improving surface properties of aluminium alloys and composites regarding wear and corrosion behaviour. Optimisation of the anodising process depends on microstructural constituents contained in aluminium alloys and represents a key task, consisting of the control of process parameters and electrolyte formulation. We applied the micro-capillary technique known from corrosion studies and modified it to form anodic aluminium oxide films on high-strength aluminium alloys in comparison… Show more
“…The oxidation potential corresponding to each particle is associated with its unique chemical composition and structure. It is important to highlight that this behaviour was previously observed in the AA2024-T3 alloy during potentiodynamic polarisation [64–67]. Figure 1 (a) Potentiodynamic polarisation curves of the AA2024-T3 and AA2198-T8 alloys obtained in 0.53 mol L −1 tartaric acid and 0.46 mol L −1 sulfuric acid (TSA) solution at 37°C carried out from OCP up to 14 V (vs. RE) with a scan rate of 1 Vmin −1 .…”
Section: Resultssupporting
confidence: 56%
“…The oxidation potential corresponding to each particle is associated with its unique chemical composition and structure. It is important to highlight that this behaviour was previously observed in the AA2024-T3 alloy during potentiodynamic polarisation [64][65][66][67].…”
“…Over the years, some research works have been carried out on this subject. For example, Zahavi et al [62], Iglesias-Rubianes et al [63], Curione et al [64], Saenz de Miera et al [65,66] and Nickel et al [67] studied the effect of micrometric particles on the anodising behaviour of the AA2024 alloy. Also, Fares et al [68,69], Bononi et al [70], Abdel-Gawad et al [71], Veys-Renaux et al [72] and Elkilany et al [73] carried out works on the effect of micrometric particles on the anodising of other alloys different from the Al-Cu-Mg series.…”
In this study, the behaviour of the micrometric particles of the AA2198-T8 alloy during anodising at various voltages and the effect of anodising voltage on the anodised surface morphology have been investigated in a tartaric-sulfuric acid anodising solution. The results were compared with that of the AA2024-T3 alloy. For the AA2198-T8 alloy, partial dissolution of these particles occurred at 0, 3 and 4 V. Besides, for potentials above 5 V, there is a preferential dissolution of the intermetallic particles. For the AA2024-T3 alloy, the results indicated a total dissolution of the micrometric particles at 0 V and a partial dissolution at 3 V, whereas above 4 V total dissolution occurred. Between 1 and 2 V, no dissolution was observed for both alloys. The preferential dissolution of the micrometric particles resulted in defects in the anodic film and cavities on the anodised surfaces.
“…The oxidation potential corresponding to each particle is associated with its unique chemical composition and structure. It is important to highlight that this behaviour was previously observed in the AA2024-T3 alloy during potentiodynamic polarisation [64–67]. Figure 1 (a) Potentiodynamic polarisation curves of the AA2024-T3 and AA2198-T8 alloys obtained in 0.53 mol L −1 tartaric acid and 0.46 mol L −1 sulfuric acid (TSA) solution at 37°C carried out from OCP up to 14 V (vs. RE) with a scan rate of 1 Vmin −1 .…”
Section: Resultssupporting
confidence: 56%
“…The oxidation potential corresponding to each particle is associated with its unique chemical composition and structure. It is important to highlight that this behaviour was previously observed in the AA2024-T3 alloy during potentiodynamic polarisation [64][65][66][67].…”
“…Over the years, some research works have been carried out on this subject. For example, Zahavi et al [62], Iglesias-Rubianes et al [63], Curione et al [64], Saenz de Miera et al [65,66] and Nickel et al [67] studied the effect of micrometric particles on the anodising behaviour of the AA2024 alloy. Also, Fares et al [68,69], Bononi et al [70], Abdel-Gawad et al [71], Veys-Renaux et al [72] and Elkilany et al [73] carried out works on the effect of micrometric particles on the anodising of other alloys different from the Al-Cu-Mg series.…”
In this study, the behaviour of the micrometric particles of the AA2198-T8 alloy during anodising at various voltages and the effect of anodising voltage on the anodised surface morphology have been investigated in a tartaric-sulfuric acid anodising solution. The results were compared with that of the AA2024-T3 alloy. For the AA2198-T8 alloy, partial dissolution of these particles occurred at 0, 3 and 4 V. Besides, for potentials above 5 V, there is a preferential dissolution of the intermetallic particles. For the AA2024-T3 alloy, the results indicated a total dissolution of the micrometric particles at 0 V and a partial dissolution at 3 V, whereas above 4 V total dissolution occurred. Between 1 and 2 V, no dissolution was observed for both alloys. The preferential dissolution of the micrometric particles resulted in defects in the anodic film and cavities on the anodised surfaces.
“…Electrochemical cells exist in centimeter to micrometer ranges. Hence, small areas can be anodically oxidized using sealed microcapillaries [ 10 ]. However, sealed cells can only be used on approximately flat surfaces and are limited in terms of the shape and size of the anodized surface.…”
Local anodization with a free electrolyte jet is a suitable solution for locally confined surface functionalization without additionally required preparation of the parts. However, the geometrical formation of the anodic oxide layer in jet-based anodization is not yet sufficiently understood. In this study, numerical calculations based on physical descriptions are used to describe the lateral and vertical oxide formation on aluminum alloy EN AW-7075. The required electrical resistance and capacitance were determined by immersion-based anodization and implemented into the numerical simulation model to evaluate the electrical conductivity of the porous layer. The simulation results showed an electrical conductivity of 2.6 ∙ 10−6 S/m for the porous layer. Subsequently, a model for jet-based anodization was developed and the previous results were implemented to calculate the oxide formation. The simulation results showed decreasing oxide layer thickness at increasing radial distance from the center of the jet, which corresponds to experimental results. The simulation model was validated by varying the current efficiency from 5% to 90%, where similar developments of the anodic oxide layer thickness compared with experimental results were determined at 5%.
“…Oxide coatings are produced on aluminium foil intended for electrodes in capacitors. Hard anodic coatings are used in the aviation and transportation industries, where the effect on environmental pollutions is increasingly discussed [1][2][3].…”
The recent trend of using aluminium alloys instead of steel has reached the transportation industry, where increasingly, more parts are made of aluminium. An example is the belt pulley, applied for combustion engines for energy transmission. This part should be strong, durable, and lightweight. Aluminium-silicon alloys are a good choice, moreover, even when the surface is anodised, also because of their moderate inertia control and excellent wear characteristic during mechanical operations. Since aluminium is lightweight yet mechanically durable and anodised, it is an ideal belt pulley to use, especially in high-temperature operations. However, the main question is what type of Al-Si alloy, casting method and anodisation method should be used in terms of energy adsorption, having long-term properties for a lifetime, has to be applied. For this reason, this paper presents the influence of the chemical composition, casting method and anodising parameters on the structure and thickness of the anodic layer produced on aluminium alloys, as well as on the albedo value as an ability to reflect or absorb light. The aluminium alloys, AlSi12Cu1 and AlSi9Cu3, were used as research materials, obtained using different casting methods. The goal of this work was to determine the optimal combination of the anodisation conditions and materials for maximising the reflectivity factor of the surface, as a very important factor, determining the energy amount absorbed by an anodised surface. For further improvement of these surface properties as well as for enhancement of the properties and strengthen the material produced with different aluminium alloys production methods, different alloying additives were added. In addition, the mechanical properties of the surface layer were measured, where a remarkable hardness increase was obtained, and the best combination in form of AlSi12Cu1 high pressure cast was found with the highest albedo factor among all tested surface variants.
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