Step Anodization Research Articles

Investigation of the Electrochemical Kinetics of Aluminum Deposition from Ionic Liquids

Aluminum is one of the first metals that has been successfully deposited from ionic liquids (ILs) and has been in the focus of intense research. However, the electrochemical kinetics of the aluminum deposition from ILs is still not fully understood.This paper will discuss recent results from the authors’ lab on the electrochemical kinetics of the deposition of aluminium from 1-ethyl-3-methyl-imidazolium based ILs. Overpotential measurements and electrochemical impedance spectroscopy (EIS) experiments were employed to extract kinetic data from potential-time transients (see Fig. 1). The transients were interpreted in terms of different contributions to the total overpotential. This includes a detailed discussion of the Ohmic drop, charge transfer, concentration and nucleation overpotential. The charge transfer mechanism of aluminum was investigated in terms of the anodic and cathodic rate-determining step (RDS) and oxidation and reduction mechanisms are suggested. Density Functional Theory (DFT) calculations were performed to evaluate if the suggested mechanism is thermodynamically reasonable.Fig. 1 Potential-time transient for a constant-current step (j = 1.25 mA cm-2) at an aluminum electrode in [EMIm]Al2Cl7 at 300 K. The inset shows the first 500 ms of the potential-time transient. Figure 1

Development of a low purity aluminum alloy (Al6082) anodization process and its application as a platinum-based catalyst in catalytic hydrogen combustion

In this study, we present a process to prepare a Pt/anodized aluminum oxide (AAO) catalyst for catalytic hydrogen combustion applications using low cost and low aluminum (Al) purity Al6082 alloy (97.5% Al) as the substrate. The effects of the anodization temperature, voltage, and time of the second anodization step on the morphological characteristics were investigated using 5 wt% phosphoric acid (H3PO4) as the electrolyte. AAO layers with semi-ordered pore arrangements were obtained by varying the anodization conditions while preserving an Al metallic core. Morphological characterization of the AAO layer was carried out with scanning electron microscopy and characterization of the Pt/AAO catalyst with transmission electron microscopy and inductively coupled plasma optical emission spectroscopy. The as-synthesized AAO layers had pore diameters of 91.0 ± 10.0 nm, interpore distances of 138.7 ± 27.4 nm, pore densities of 68 ± 15 pores/μm2, and 39% porosity. Pt/AAO catalyst had a Pt loading and Pt particle size of 1.01 ± 0.11 wt% and of 4.7 ± 2.0 nm, respectively. During catalytic hydrogen combustion, a stable combustion temperature of 338 ± 11 °C was maintained for 530 h and no Pt aggregation nor support degradation was evident.

Anodization: Recent Advancements on Corrosion Protection of Brake Calipers

<div class="section abstract"><div class="htmlview paragraph">Brake calipers for high-end cars are typically realized using Aluminum alloys, with Silicon as the most common alloying element. Despite the excellent castability and machinability of Aluminum-Silicon alloys (AlSi<i>x</i>), anodization is often required in order to increase its corrosion resistance. This is particularly true in Chlorides-rich environments where Aluminum can easily corrode. Even if anodization process is known for almost 100 years, anodization of AlSi<i>x</i> -based materials is particularly challenging due to the presence of eutectic Silicon precipitates. These show a poor electric conductivity and a slow oxidation kinetics, leading to inhomogeneous anodic layers. Continuous research and process optimization are required in order to develop anodic layers with enhanced morphological and electrochemical properties, targeting a prolonged resistance of brake calipers under endurance corrosive tests (e.g. >1000 hours Neutral Salt Spray (NSS) tests). In this manuscript a lab-scale anodization setup is used to investigate the interplay between process parameters, oxide layer morphology and corrosion protection capability. The influence of high anodization steps (AS) and low rest steps (RS) in pulsed anodization waveforms is investigated with respect to the homogeneity and compactness of the obtained oxide layers. In comparison with a conventional set of anodization parameters, which is taken as a standard, the following level of performance are achieved: 1) increase of the corrosion potential (Ecorr) of +98mV; 2) increase of the anodic breakdown potential (Ebp) of +362mV; 3) reduction of the corrosion rate of a factor six; and 4) a polarization resistance 1.5 times higher. This work identifies key parameters in the anodization of Aluminum-Silicon alloys and propose new electrochemical figures of merit in order to: a) extend the corrosion resistance of future braking systems; and b) evaluate <i>ex-situ</i> the anodic layer electrochemical performance.</div></div>

High-efficiency photoelectrochemical cathodic protection performance of the iron-nitrogen-sulfur-doped TiO2 nanotube as new efficient photoanodes

Novel iron-nitrogen-sulfur-tridoped titanium dioxide nanotubes (Fe-N-S-TiO2 NTs) have been synthesized via single step anodization of titanium using potassium ferricyanide, as a suitable additive, in dimethyl sulfoxide (DMSO) electrolyte and applied as photoanodes in the photocathodic protection of stainless steel 403 (SS403). Photocurrent density, open circuit potential and Tafel polarization curves have been used to study the photocathodic protection effect of the samples prepared. Upon the addition of potassium ferricyanide to the anodizing electrolyte and titanium dioxide nanotube doping, the light absorption of the Fe-N-S-TiO2 NTs were increased to the visible region, comparable with pure TiO2 NTs, according to the results obtained. Enhanced photoelectro-response activity and photocathodic protection performance for 403 stainless steel are exhibited by Fe-N-S-TiO2 NTs under light illumination. In addition, the optimal sample electrode (FT4) potentials shifted negatively to −683 mV under illumination.

Effect of hydrothermal treatment on porous anodic alumina generated by one-step anodization

Abstract The effects of the hydrous oxide film obtained from the hydrothermal treatment of the electropolished aluminum sheet on the porous anodic alumina produced by the first step of anodization in oxalic acid were investigated. It is indicated that the dense barrier layer within the hydrous oxide film can bring about a nearly exponential decrease of the current as a function of time. As to the porous layer of the hydrous oxide film, namely the ‘cornflake’ structure onto the barrier layer, it can optimize the initially nucleated site of the nanoporous during the anodization, which is beneficial to the self-ordered array of the nanoporous generated on the PAA film. It is concluded that the hydrous oxide film produced by the hydrothermal treatment can facilitate the self-assembly of the porous anodic alumina even if the applied potential is 60 V in oxalic acid.

Hematite (α-Fe2O3) nanosheets with enhanced photo-electrochemical ability fabricated via single step anodization

In the present study, synthesis of hematite nanosheets and their photocurrent response have been reported. The nanosheets are fabricated through a single step-anodization technique at room temperature. Light absorption study of nanosheets, using diffuse-reflectance-spectroscopy, depicts the band gap of ~2.16 eV. Photocurrent density of as-fabricated nanosheets is found to be ~0.72 mA cm−2. The enhanced photocurrent density as compared to iron oxide based photoelectrodes can be attributed to high surface area for light absorption and good crystallinity. These features improve the charge separation to overcome charge carrier recombination which favours their preference as a promising candidate for visible-light driven applications.

Aluminum based reflective nanolens arrays to improve the effectiveness of ultraviolet inactivation of Escherichia coli O157:H7 and Listeria monocytogenes in water and a sucrose solution.

Aluminum based reflective nanolens arrays were developed via a series of aluminum electropolishing and anodization steps with subsequent selective dissolution of anodic aluminum oxide (AAO). The diameter of nanolenses (d) on arrays can be controlled by altering electrolytes and voltages used for aluminum anodization. The d values of arrays produced by anodization in 0.3M oxalic acid at 40, 60, and 80V, and in 1.0M phosphoric acid at 100, 110, and 120V were 71.94, 121.90, and 161.53nm, and 220.16, 252.06, and 274.78nm, respectively. The effectiveness of UV (254nm) inactivation of Escherichia coli O157:H7 and Listeria monocytogenes at concentrations of 5-6 log CFU/mL in water and in a 10% (w/v) sucrose solution was improved using a nanolens array having a d value of 252.06nm.

Ordered Ti-Fe-O nanotubes as additive-free anodes for lithium ion batteries

Manufacturing of binder-free mixed oxide electrodes with an unique 1D tubular morphology, high lithium storage ability and long durability represents a real challenge to assemble efficient lithium ion batteries for safe operation. Herein, the successful fabrication of mixed Ti-Fe-O nanotubes (NTs) by a single potentiostatic anodization step of a TiFe12 alloy at room temperature is reported. With the help of suitable characterization tools, the mixed oxide tubes in the different preparation stages were investigated for crystallinity and phase formation including an analysis on the structure defects which influence the material´s performance. Their morphology and element distribution were evaluated in the bulk and on the surface as well as oxidation state changes of the transition metal elements and the solid-electrolyte interphase formation were investigated up to the operando mode. The high anodization voltage along with the substrate composition induced the formation of a thin membrane layer covering the top of Ti-Fe-O NTs. The electrochemical performance of NTs as potential anodes in Li-ion batteries was evaluated vs. Li/Li+ without any binder or conductive additives. The effect of the annealing temperature on crystallinity and Li-ion storage ability of NTs was investigated as well. The Ti-Fe-O NTs electrodes demonstrated an initial discharge capacity of 291 mAh g−1 at a current rate of 0.15C (1C = 335 mA g−1). The annealed crystalline NTs showed a higher reversible capacity of 155 mAh g−1 than the amorphous nanotubes after direct fabrication at room temperature (98 mAh g−1) after 50 charging/discharging cycles with a Coulombic efficiency close to 100% without a provable decomposition of the tubular structure but slight visible changes in their morphology. The noticed increase of the capacity of the Ti-Fe-O NT arrays treated at 600 °C is attributed to the enhanced ionic conductivity originated from short pathways for the Li+ ion transport across the grain boundaries of the crystalline domains. In contrast, the presence of point defects, atomic displacements and planes sliding in the amorphous matrixes surrounding the crystalline entities hinder Li+ ion transport through scattered diffusion pathways, and hence a lower lithium storage is demonstrated.

Electronic Properties of Oxidized Cyclometalated Diiridium Complexes: Spin Delocalization Controlled by the Mutual Position of the Iridium Centers.

Four cyclometalated diiridium complexes, with IrCp*Cl (Cp*=η5 -C5 Me5 - ) termini bridged by 1,4- and 1,3-bis(p-tolyliminoethyl)benzene (1, 2), or 1,4- and 1,3-bis(2-pyridyl)benzene (3, 4), were prepared and characterized by nuclear magnetic resonance (NMR) spectroscopy and single-crystal X-ray diffraction (complexes 1, 2, and 4). The two iridium centers in complexes 1 and 3 are thus bound at the central benzene ring in the para-position (trans-Ir2), whereas those in complexes 2 and 4 are in the meta-position (cis-Ir2). Cyclic voltammograms of all four complexes show two consecutive one-electron oxidations. The potential difference between the two anodic steps in 1 and 3 is distinctly larger than that for 2 and 4. The visible-near-infrared (NIR)-short-wave infrared (SWIR) absorption spectra of trans-Ir2 monocations 1+ and 3+ are markedly different from those of cis-Ir2 monocations 2+ and 4+ . Notably, strong near-infrared electronic absorption appears only in the spectra of 1+ and 3+ whereas 2+ and 4+ absorb only weakly in the NIR-SWIR region. Combined DFT and TD-DFT calculations have revealed that (a) 1+ and 3+ (the diiridium-benzene trans-isomers) display the highest occupied spin-orbitals (HOSO) and the lowest unoccupied spin-orbital (LUSO) evenly delocalized over both molecule halves, and (b) their electronic absorptions in the NIR-SWIR region are attributed to mixed metal-to-ligand and ligand-to-ligand charge transfers (MLCT and LLCT). In contrast, cis-isomers 2+ and 4+ do not feature this stabilizing π-delocalization but a localized mixed-valence state showing a weak intervalence charge-transfer (IVCT) absorption in the SWIR region.

Synthesis of Heterogeneously Conductive Polypyrrole Layer from Non-Aqueous Solution Using The Double-Step Potential Technique

In this research we have investigated electrochemical formation of conducting polymer—polypryrrole (Ppy)—by multi-pulse/double-step potential (MpDsP) mode. Ppy layers were electrochemically formed from different concentrations of pyrrole, tetrabutylammonium hexafluorophosphate salt (TBAPF6) in acetonitrile-based (AcN) electrolyte (AcN-TBAPF6). It was determined that during the first anodic potential step the discharge current is significantly higher in comparison to that observed during the next anodic potential step. We conclude that this effect is related to the formation of pyrrole “ad-layer” before the engagement of electrochemical oxidation of pyrrole. During long-lasting formation of Ppy layer the capacitance of double-layer has increased significantly. Electrochemical impedance spectroscopy (EIS) data also showed that double-layer capacitance increases. Such increase of double-layer capacitance is determined by increasing effective electrochemically active surface area of conducting polymer—polypyrrole. However, at the same time, during the formation of Ppy layer by MpDsP approach the increase of reactive impedance (Zreal) has been observed. This effect was the most significant when higher concentrations (25 and 50 mM) of pyrrole in AcN-TBAPF6 based solutions were applied for the formation of Ppy layer. Therefore, we conclude that at increased pyrrole concentrations more homogenous and smooth Ppy layer is formed. However, at the same time the surface of Au-based electrode becomes homogenously blocked by overoxidized Ppy (Ppy(overox)), which has lower conductivity in comparison to that of initially formed Ppy. At low concentration of pyrrole monomer, the Au-based electrode surface is covered by heterogenic layer of Ppy, which is composed of different clusters, which are forming Ppy/Ppy(overox) zones of different conductivity.

Combined Treatment on an Al Surface to Improve the Metal-Polymer Adhesion Strength.

The development of mobile industries and urban transportation today requires nanotechnology for research and processing of metallic surfaces. Here, aluminum alloys (Al) are the most common material with the best physical properties that need to be treated. The advantages of Al in manufacturing are obvious; however, the Al surface is sensitive to the presence of acid or base, and thus protecting the Al surface is mandatory. In this study, Al surfaces have been subjected to a new surface treatment process that includes sandblasting, anodizing, and subsequent post-etching steps. The treated surfaces are evaluated by surface morphology including contact angle measurement and polymer adhesion strength. The adhesion strength of blasted Al-polymer assemblies with and without an anodizing step have been performed with a single lap shear test. This clearly shows the profound effect of the combined treatment process. The results reveal that a combination of high surface roughness and area as well as a thick Al₂O₃ layer with micro-cavities created by a post-etch step can significantly improve the adhesion strength of the Al-polymer. This, in turn, enhances the quality of and longevity of Al surface in production and application.

Role of magnesium doping for ultrafast room temperature crystallization and improved photocatalytic behavior of TiO2 nanotubes

In this work, a simple and cost effective two step anodization method is used to prepare Magnesium doped TiO2 nanotubes (Mg-TONTs) which demonstrate superior photocatalytic performance. Room temperature (28 °C) crystallization of well alligned TONTs is achieved by Mg doping within a record time of 10 s whereas undoped samples prepared at 28 °C are amorphous. Mg-TONTs possess a photocatalytic degradation rate of 0.006/min which is 5 times higher than that by undoped amorphous TONT (0.0015/min) for the degradation of the organic pollutant methylene blue. The samples are morphologically, structurally, compositionally as well as optically characterised by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectrometer (DRS). FESEM reveal perfect tubular structure even after Mg doping with no Mg overlayer at the top of the tube. XRD and TEM confirm the polycrystalline nature of the tube and attainment of room temperature crystallization with a prominent peak at 25.100 and 47.80° in the former. XPS peak at ∼1303.5 eV corresponding to Mg1s confirms the formation of Mg bonding in the compound. The optical study indicates a decrease in the band gap of the doped sample that enables visible photon absorption that contributes to the enhanced photocatalytic activity.

Ionic direct current modulation evokes spike-rate adaptation in the vestibular periphery

Recent studies have shown that ionic direct current (iDC) can modulate the vestibular system in-vivo, with potential benefits over conventional pulsed stimulation. In this study, the effects of iDC stimulation on vestibular nerve fiber firing rate was investigated using loose-patch nerve fiber recordings in the acutely excised mouse crista ampullaris of the semicircular canals. Cathodic and anodic iDC steps instantaneously reduced and increased afferent spike rate, with the polarity of this effect dependent on the position of the stimulating electrode. A sustained constant anodic or cathodic current resulted in an adaptation to the stimulus and a return to spontaneous spike rate. Post-adaptation spike rate responses to iDC steps were similar to pre-adaptation controls. At high intensities spike rate response sensitivities were modified by the presence of an adaptation step. Benefits previously observed in behavioral responses to iDC steps delivered after sustained current may be due to post-adaptation changes in afferent sensitivity. These results contribute to an understanding of peripheral spike rate relationships for iDC vestibular stimulation and validate an ex-vivo model for future investigation of cellular mechanisms. In conjunction with previous in-vivo studies, these data help to characterize iDC stimulation as a potential therapy to restore vestibular function after bilateral vestibulopathy.

Yttrium incorporated BiFeO3 nanostructures growth on two step anodized Al2O3 porous template for energy storage applications

Porous anodic aluminum oxide templates with average pore size of approximately 100 nm were synthesized by two step anodization processes. Pure and Yttrium substituted BiFeO3 nano-structures with different concentrations were hydrothermally grown on anodic aluminum oxide templates to explore its various physical properties. X-ray diffraction was employed to extract the crystallographic information revealed the formation of rhombohedral geometry with R-3c space group. Field emission scanning electron microscopy displayed the filling up of pores with growth of distorted diamond and flakes like BiFeO3 and Yttria enriched nanostructures, respectively. Energy dispersive X-ray spectroscopy was confirmed the presence of expected elemental contents in each template. UV–Vis spectrophotometry recorded a significant increment in optical absorption of AAO template with growth of nanostructures. The value of optical band gap was found to decrease from 2.49 eV to 2.02 eV with incorporation of metallic yttrium content. Dielectric permittivity was found to increase substantially from 19 to 159 in Yttria containing nano-flakes with comparatively low loss factor of 0.84 disclosed these templates as prominent candidate for energy storage applications.

Use of ultrasound irradiation during acid etching of the 2024 aluminum alloy: Effect on corrosion resistance after anodization.

While aluminum alloys are widely used in industrial applications, their protection by anodization as surface treatment always requires a preparation step by alkaline or acid etching. In this paper, use of ultrasound during the acid etching step on the 2024 aluminum alloy was investigated. Etching rate, calculated as of weight loss, was measured under ultrasound irradiation, and compared to silent conditions. The etched surface was characterized by Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) and X-Ray Diffraction (XRD). Surface treatment was performed up to the final anodization step samples, and their final properties were evaluated as a function of various pre-treatments, including acid etching under ultrasound. The main evaluation concerned anticorrosion properties through electrochemical tests: polarization measurements and electrochemical impedance spectroscopy (EIS) in NaCl solution. Finally, use of ultrasound irradiation during acid preparation induced a beneficial effect on the corrosion performance of the anodic layer.

Constructing geometrically-ordered alumina nanoporous filters and alumina nanowire arrays by using ultrahigh voltage two step anodization

Abstract A simple ultrahigh voltage two-step anodization was developed to fabricate nanopore and nanowire arrays which can be utilized in various applications like water purification filter technology. Investigation of the electrolyte concentration effect on controlling the morphology and geometry of the alumina nanopore and nanowire (ANW) arrays has been done. The anodization was carried out in H2C2O4/H3PO4 mixture at about 0 °C to reach the best ordered nanopores array. In hard anodization step, the current density showed a peak shape profile so that its maximum was directly depended on the H3PO4 concentration. The SEM images of the arrays were studied by image histogram and fast Fourier transform (FFT). The model curves demonstrated direct dependency of the nanopores ordering on electrolyte concentration. The most ordered array was achieved by utilizing 0.3 M H2C2O4 and 0.35 M H3PO4. The SEM images showed that the pores became wider by etching the nanopores in an acidic solution. In addition, fast fabrication of nanowire arrays was achieved by managing the anodization process at 30 °C in a short time. The ANWs were obtained from nanopores etching through the anodization, without an extra etching step requirement. The studies on SEM images demonstrated succeeding high ordered ANWs bundle.

In-situ removal of thick barrier layer in nanoporous anodic alumina by constant current Re-anodization

A novel method for thick barrier layer removal of nanoporous anodic alumina (NAA) based on a constant current re-anodization (third anodization step) is reported. The barrier layer consists of an alumina layer that prevents electrical contact between the inner pore volume and the aluminium substrate. Several methods have been reported for the removal of such alumina layer. However, none of them is applicable to NAA produced under high anodization voltages, for example with phosphoric acid (H3PO4) electrolyte. Herein, NAA is obtained by two-step anodization of aluminium at a constant voltage of 195 V in a H3PO4 electrolyte. The novelty of this study consists of the combination of a reduction of the barrier layer thickness with a partial chemical etching in a H3PO4 solution followed by a constant current re-anodization step. This opens branchings in the barrier layer that permit a complete removal with a final chemical etching step in H3PO4 solution. The best condition for removing the barrier layer in the constant current re-anodization step is to fix a constant density current of 17.0 μA/cm2. We obtain self-ordered NAA substrates without barrier layer, allowing for the establishment of an electrical contact between the aluminium substrate and the interior of the nanopores. These nanoporous-back metal contact structures can be very important for applications in energy generation, energy storage and optoelectronic devices.

Post treatments effect on TiZr nanostructures fabricated via anodizing

The primary focus of the paper is the fabrication of nanotubes via a two steps anodizing procedure on a TiZr substrate followed subsequent annealing treatments and their effect on surface and biocompatibility. The two step anodizing process is optimized for obtaining uniform and ordered nanotubular structures, that are then annealed in air or reduced in an Ar/H2 environment. The high aspect ratio nanotubular structures (diameter 160 nm, length 9.4 μm) maintained their morphology after annealing or reduction. While the thermal treatments burned-off the fluoride, they converted the tubes to ZrTiO4 (annealing in air) or (Zr0.333 Ti0.666)O2 (reducing). Surface roughness and adhesion forces evaluation of the nanostructures was included in the AFM investigations, and show that these properties can be tuned. In vitro cell response to TiZr substrate and nanotubular coatings were analyzed using HGF-1 gingival fibroblasts cell line and LDH, nitric oxide (NO) and reactive oxygen species (ROS) tests. Regarding the hydrophilic balance of the studied samples, as expected it decreased after annealing and but increased after reduction, with only small change in the cell response. The results suggest that these coatings are biocompatible with human gingival fibroblast and can be used in biomedical applications without generating any considerable inflammatory process.

Highly ordered combined structure of anodic TiO2 nanotubes and TiO2 nanoparticles prepared by a novel route for dye-sensitized solar cells

Combined structure of anodic TiO2 nanotubes and TiO2 nanoparticles (TiNTs-TiNPs) has been synthesized by a facile combination of hydrothermal and chemical vapor deposition methods. Ordered TiO2 nanotubes with smooth walls were fabricated by two step anodization method in ethylene glycol containing NH4F at 50 V. This nanotubular array after annealing at 450 °C was subjected to the hydrothermally produced gaseous environment in an autoclave with diluted TiCl4 solution at its bottom. Vapors of TiCl4 were allowed to react chemically with water vapors for predefined time durations at 180 °C that resulted in the deposition of TiO2 nanoparticles on tubes’ surface and side walls. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that for one hour reaction duration, nanoparticles were evenly coated on the walls of nanotubes, whereas, longer durations tend to deteriorate the tubular structure. Consequently, the ordered TiNTs-TiNPs array produced after one hour coating has shown better performance for dye-sensitized solar cell DSSC) in back illumination mode with 130% increase in efficiency as compared to the device based on bare TiO2 nanotubes. The same photoanode has higher reflective properties with higher scattering ability. The solar cell based on this photoanode exhibits higher external quantum efficiency and effective charge transport properties. This study shows that porous ordered 1D structures based on TiO2 are of crucial importance for the high performance of DSSCs.

Complex influence of temperature on oxalic acid anodizing of aluminium

Two-step aluminium anodizing is widely used to prepare oxide films with a highly-ordered porous structure through the whole thickness. It can be realized solely at relatively low values of current density in the kinetic anodizing regime that makes this process extremely time-consuming. Temperature is an important thermodynamic parameter which is able to accelerate chemical reactions and mass-transport and, thus, could be suggested as an effective tool to control the growth rate of anodic alumina. Here we report a systematic study of the porous anodic alumina films formation in 0.3 M oxalic acid electrolyte in a wide temperature range. The influence of electrolyte temperature on the kinetics of aluminium anodizing and on the morphology of the obtained anodic alumina films is addressed quantitatively. Current transients registered at various temperatures are used for the calculation of the apparent activation energy of the anodization process in both mild and hard anodizing regimes. In the case of thick oxide films and high electrolyte temperature, the increase in diffusion current contribution leads to switching the kinetically controlled anodizing to the mixed regime which results in destroying the hexagonal pore ordering. Based on the experimental findings, rational electrolyte temperatures and porous layer thicknesses for the first and second anodizing steps are proposed as a guide for express preparation of alumina films with well-ordered porous structure.