Research

14 pages, 2102 KiB

Open AccessEditor’s ChoiceArticle

Modification of Anodic Titanium Oxide Bandgap Energy by Incorporation of Tungsten, Molybdenum, and Manganese In Situ during Anodization

by Marta Michalska-Domańska, Katarzyna Prabucka and Mateusz Czerwiński

Materials 2023, 16(7), 2707; https://doi.org/10.3390/ma16072707 - 28 Mar 2023

Cited by 2 | Viewed by 1559

Abstract

In this research, we attempted to modify the bandgap of anodic titanium oxide by in situ incorporation of selected elements into the anodic titanium oxide during the titanium anodization process. The main aim of this research was to obtain photoactivity of anodic titanium [...] Read more.

In this research, we attempted to modify the bandgap of anodic titanium oxide by in situ incorporation of selected elements into the anodic titanium oxide during the titanium anodization process. The main aim of this research was to obtain photoactivity of anodic titanium oxide over a broader sunlight wavelength. The incorporation of the selected elements into the anodic titanium oxide was proved. It was shown that the bandgap values of anodic titanium oxides made at 60 V are in the visible region of sunlight. The smallest bandgap value was obtained for anodic titanium oxide modified by manganese, at 2.55 eV, which corresponds to a wavelength of 486.89 nm and blue color. Moreover, it was found that the pH of the electrolyte significantly affects the thickness of the anodic titanium oxide layer. The production of barrier oxides during the anodizing process with properties similar to coatings made by nitriding processes is reported for the first time. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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17 pages, 8020 KiB

Open AccessArticle

Dependence of the Surface Morphology and Micromechanical and Sclerometric Properties of Al₂O₃ Layers on the Parameters of Anodizing Aluminum Alloy

by Mateusz Niedźwiedź, Marek Bara and Adrian Barylski

Materials 2022, 15(23), 8482; https://doi.org/10.3390/ma15238482 - 28 Nov 2022

Cited by 5 | Viewed by 900

Abstract

The article presents the dependence of the morphology as well as micromechanical and sclerometric properties of Al₂O₃ layers on the parameters of anodizing of aluminum alloys. The oxide layers were produced on the EN AW-5251 aluminum alloy by means of [...] Read more.

The article presents the dependence of the morphology as well as micromechanical and sclerometric properties of Al₂O₃ layers on the parameters of anodizing of aluminum alloys. The oxide layers were produced on the EN AW-5251 aluminum alloy by means of a direct current anodizing in a three-component electrolyte. The input variables (current density and electrolyte temperature) were selected based on the overall design of the experiment. The current density was 1, 2, 3 A/dm², and the electrolyte temperature was 283, 293, 303 K. The surface morphology was examined using a scanning electron microscope (SEM), and then the microscopic images were analyzed using a graphics program. The micromechanical and sclerometric properties were examined by determining the H_IT hardness and three critical loads: Lc1 (critical load at which the first damage of the tested layers occurred-Hertz tensile cracks inside the crack), Lc2 (critical load at which the first cohesive damage of the layers occurred) and Lc3 (load at which the layers were completely damaged). Sclerometric tests with the use of scratch tests were supplemented with pictures from a scanning microscope, showing the scratches. The produced layers are characterized by a hardness above 3 GPa and a porosity of 4.9–10.3%. Such a range of porosity of the produced layers allows their wide application, both for sliding associations with polymers and for their modification. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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21 pages, 6039 KiB

Open AccessArticle

Corrosion Resistance of Aluminum Alloy AA2024 with Hard Anodizing in Sulfuric Acid-Free Solution

by José Cabral Miramontes, Citlalli Gaona Tiburcio, Estefanía García Mata, Miguel Ángel Esneider Alcála, Erick Maldonado-Bandala, Maria Lara-Banda, Demetrio Nieves-Mendoza, Javier Olguín-Coca, Patricia Zambrano-Robledo, Luis Daimir López-León and Facundo Almeraya Calderón

Materials 2022, 15(18), 6401; https://doi.org/10.3390/ma15186401 - 15 Sep 2022

Cited by 8 | Viewed by 2009

Abstract

In the aeronautical industry, Al-Cu alloys are used as a structural material in the manufacturing of commercial aircraft due to their high mechanical properties and low density. One of the main issues with these Al-Cu alloy systems is their low corrosion resistance in [...] Read more.

In the aeronautical industry, Al-Cu alloys are used as a structural material in the manufacturing of commercial aircraft due to their high mechanical properties and low density. One of the main issues with these Al-Cu alloy systems is their low corrosion resistance in aggressive substances; as a result, Al-Cu alloys are electrochemically treated by anodizing processes to increase their corrosion resistance. Hard anodizing realized on AA2024 was performed in citric and sulfuric acid solutions for 60 min with constant stirring using current densities 3 and 4.5 A/dm². After anodizing, a 60 min sealing procedure in water at 95 °C was performed. Scanning electron microscopy (SEM) and Vickers microhardness (HV) measurements were used to characterize the microstructure and mechanical properties of the hard anodizing material. Electrochemical corrosion was carried out using cyclic potentiodynamic polarization curves (CPP) and electrochemical impedance spectroscopy (EIS) in a 3.5 wt. % NaCl solution. The results indicate that the corrosion resistance of Al-Cu alloys in citric acid solutions with a current density 4.5 A/dm² was the best, with corrosion current densities of 2 × 10⁻⁸ and 2 × 10⁻⁹ A/cm². Citric acid-anodized samples had a higher corrosion resistance than un-anodized materials, making citric acid a viable alternative for fabricating hard-anodized Al-Cu alloys. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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12 pages, 2557 KiB

Open AccessArticle

ORMOSIL Coatings Enriched with CeO₂ (5-ATDT)-Ceramic Nanocontainers for Enhanced Protection of HDG Steel Used in Concrete

by George Kordas

Materials 2022, 15(11), 3913; https://doi.org/10.3390/ma15113913 - 31 May 2022

Cited by 1 | Viewed by 1306

Abstract

This paper reports developing an innovative method of anticorrosion protection based on organically modified silica (ORMOSIL) enriched with CeO₂ ceramic nanocontainers loaded with 5-amino-1, 3, 4-thiadiazole-2-thiol (5-ATDT) on hot-dip galvanized zinc (HDG) steel used to strengthen cement in concrete. The chemistry of [...] Read more.

This paper reports developing an innovative method of anticorrosion protection based on organically modified silica (ORMOSIL) enriched with CeO₂ ceramic nanocontainers loaded with 5-amino-1, 3, 4-thiadiazole-2-thiol (5-ATDT) on hot-dip galvanized zinc (HDG) steel used to strengthen cement in concrete. The chemistry of ORMOSIL coatings and the production of CeO₂ ceramic nanocontainers are described in detail for reproduction by other researchers. The anticorrosion properties of these novel coatings were investigated through frequency response analysis (FRA). As a result, the coatings HDG-ORMOSIL + CeO₂ (5-ATDT) were better than the samples of HDG steel, HDG-ORMOSIL, and HDG-ORMOSIL + CeO₂ (EMPTY) by a factor of 1033.60, 109.21, and 7.76 in terms of anticorrosion protection, respectively. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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15 pages, 2545 KiB

Open AccessArticle

Nanostructure and Morphology of the Surface as Well as Micromechanical and Sclerometric Properties of Al₂O₃ Layers Subjected to Thermo-Chemical Treatment

by Marek Bara, Mateusz Niedźwiedź, Władysław Skoneczny and Adrian Barylski

Materials 2022, 15(3), 1051; https://doi.org/10.3390/ma15031051 - 29 Jan 2022

Cited by 4 | Viewed by 1203

Abstract

The article presents the effect of the thermo-chemical treatment of Al₂O₃ layers on their nanostructure, surface morphology, chemical composition as well as their micromechanical and sclerometric properties. Oxide layers were produced on EN AW-5251 aluminium alloy (AlMg₂) by [...] Read more.

The article presents the effect of the thermo-chemical treatment of Al₂O₃ layers on their nanostructure, surface morphology, chemical composition as well as their micromechanical and sclerometric properties. Oxide layers were produced on EN AW-5251 aluminium alloy (AlMg₂) by the method of direct current anodizing in a three-component electrolyte. The thermo-chemical treatment was carried out in distilled water and aqueous solutions of Na₂SO₄·10H₂O and Na₂Cr₂O₇·2H₂O. It was shown that the thermo-chemical treatment process changes the morphology of the surface of the layers (the formation of a sub-layer from the Na₂SO₄·10H₂O and Na₂Cr₂O₇·2H₂O solutions), which directly increases the thickness of the layers by 0.37 and 1.77 µm, respectively. The thermo-chemical treatment in water also resulted in the formation of a 0.63 µm thick sub-layer. The micromechanical tests indicated a rise in the surface microhardness of the layers in the case of their thermo-chemical treatment in water and the Na₂SO₄·10H₂O solution and a decrease in the case of the layers modified in the Na₂Cr₂O₇·2H₂O solution. The highest microhardness (7.1 GPa) was exhibited by the layer modified in the Na₂SO₄·10H₂O solution. Scratch tests demonstrated that the thermo-chemically treated layers had better adhesive properties than the reference layer. The best scratch resistance was exhibited by the layer after thermo-chemical treatment in the Na₂SO₄·10H₂O solution (the highest values, practically for all the critical loads) which, together with its low roughness and high load capacity, predispose it to sliding contacts. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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22 pages, 23487 KiB

Open AccessArticle

Al₂O₃/WS₂ Surface Layers Produced on the Basis of Aluminum Alloys for Applications in Oil-Free Kinematic Systems

by Joanna Korzekwa, Marek Bara and Sławomir Kaptacz

Materials 2021, 14(24), 7738; https://doi.org/10.3390/ma14247738 - 15 Dec 2021

Cited by 3 | Viewed by 1478

Abstract

The article presents the results of an aluminum oxide layer doped with monolayer 2H tungsten disulphide (Al₂O₃/WS₂) for applications in oil-free kinematic systems. The results concern the test carried out on the pneumatic actuator operational test stand, [...] Read more.

The article presents the results of an aluminum oxide layer doped with monolayer 2H tungsten disulphide (Al₂O₃/WS₂) for applications in oil-free kinematic systems. The results concern the test carried out on the pneumatic actuator operational test stand, which is the actual pneumatic system with electromagnetic control. The cylinders of actuators are made of Ø 40 mm aluminum tube of EN-AW-6063 aluminum alloy which is used in the manufacture of commercial air cylinder actuators. The inner surfaces of the cylinder surfaces were covered with an Al₂O₃/WS₂ oxide layer obtained by anodic oxidation in a three-component electrolyte and in the same electrolyte with the addition of tungsten disulfide 2H-WS₂. The layers of Al₂O₃ and Al₂O₃/WS₂ obtained on the inner surface of the pneumatic actuators were combined with a piston ring made of polytetrafluoroethylene with carbon (T5W) material and piston seals made of polyurethane (PU). The cooperation occurred in the conditions of technically dry friction. After the test was carried out, the scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) analysis of the surface of the cylinder bearing surfaces and piston seals of the pneumatic cylinders was performed. The analysis revealed the formation of a sliding film on the cylinder surface modified with tungsten disulfide, as well as on the surface of wiper seals. Based on the SEM/EDSM tests, it was also found that the modification of the Al₂O₃ layer with tungsten disulfide contributed to the formation of a sliding film with the presence of WS₂ lubricant, which translated into smooth cylinder operation during 180 h of actuator operation. The cylinder with the unmodified layer showed irregular operation after approximately 70 h thereof. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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14 pages, 5323 KiB

Open AccessArticle

Morphological and Optical Characterization of Colored Nanotubular Anodic Titanium Oxide Made in an Ethanol-Based Electrolyte

by Marta Michalska-Domańska, Mateusz Czerwiński, Magdalena Łazińska, Vikas Dubey, Marcin Jakubaszek, Zbigniew Zawadzki and Jerzy Kostecki

Materials 2021, 14(22), 6992; https://doi.org/10.3390/ma14226992 - 18 Nov 2021

Cited by 5 | Viewed by 1913

Abstract

In this paper, the possibility of color controlling anodic titanium oxide by changing anodizing conditions of titanium in an ethanol-based electrolyte is demonstrated. Colored anodic titanium oxide was fabricated in an ethanol-based electrolyte containing 0.3 M ammonium fluoride and various amounts of deionized [...] Read more.

In this paper, the possibility of color controlling anodic titanium oxide by changing anodizing conditions of titanium in an ethanol-based electrolyte is demonstrated. Colored anodic titanium oxide was fabricated in an ethanol-based electrolyte containing 0.3 M ammonium fluoride and various amounts of deionized water (2, 3.5, 5, or 10 vol%), at voltages that varied from 30 to 60 V and at a constant anodization temperature of 20 °C. Morphological characterization of oxide layers was established with the use of a scanning electron microscope. Optical characterization was determined by measuring diffusion reflectance and calculating theoretical colors. The resulting anodic oxides in all tested conditions had nanotubular morphology and a thickness of up to hundreds of nanometers. For electrolytes with 3.5, 5, and 10 vol% water content, the anodic oxide layer thickness increased with the applied potential increase. The anodic titanium oxide nanotube diameters and the oxide thickness of samples produced in an electrolyte with 2 vol% water content were independent of applied voltage and remained constant within the error range of all tested potentials. Moreover, the color of anodic titanium oxide produced in an electrolyte with 2 vol% of water was blue and was independent from applied voltage, while the color of samples from other electrolyte compositions changed with applied voltage. For samples produced in selected conditions, iridescence was observed. It was proposed that the observed structural color of anodic titanium oxide results from the synergy effect of nanotube diameter and oxide thickness. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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8 pages, 1776 KiB

Open AccessArticle

Tuning the Photoelectrochemical Properties of Narrow Band Gap Nanoporous Anodic SnO_x Films by Simple Soaking in Water

by Magdalena Gurgul, Marcin Kozieł and Leszek Zaraska

Materials 2021, 14(7), 1777; https://doi.org/10.3390/ma14071777 - 03 Apr 2021

Cited by 5 | Viewed by 1731

Abstract

Nanoporous tin oxide layers obtained via anodic oxidation of metallic tin at the potential of 4 V in the alkaline electrolyte (1 M NaOH) were soaked in distilled water for various durations (from 2 h to 120 h) to verify the influence of [...] Read more.

Nanoporous tin oxide layers obtained via anodic oxidation of metallic tin at the potential of 4 V in the alkaline electrolyte (1 M NaOH) were soaked in distilled water for various durations (from 2 h to 120 h) to verify the influence of water-enabled crystallization on the morphology, composition, and related optical and photoelectrochemical properties of such kind of anodic SnO_x. Although water soaking generally contributes to more stoichiometric and crystalline tin oxide, it was confirmed that at the initial stages of the water-induced dissolution–redeposition process, material exhibits enhanced photoelectrochemical performance under simulated sunlight irradiation. However, long-time exposure to water results in a gradual widening of the material’s band gap, shifting of the photoelectrochemical spectra towards higher energies, and almost complete deterioration of the photoelectrochemical activity under sunlight irradiation. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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12 pages, 3623 KiB

Open AccessArticle

Self-Organized Anodic Oxides on Titanium Alloys Prepared from Glycol- and Glycerol-Based Electrolytes

by Marta Michalska-Domańska, Magdalena Łazińska, Justyna Łukasiewicz, Johannes M. C. Mol and Tomasz Durejko

Materials 2020, 13(21), 4743; https://doi.org/10.3390/ma13214743 - 23 Oct 2020

Cited by 17 | Viewed by 2081

Abstract

The anodization of commercially pure Ti alloy (99.5 wt %) and two biomedical titanium alloys, Ti6Al7Nb and Ti6Al4V, was performed, and the resulting anodic oxides were studied. The biomedical alloys were made by Laser Engineered Net Shaping. The glycol-based and glycerol-based electrolytes with [...] Read more.

The anodization of commercially pure Ti alloy (99.5 wt %) and two biomedical titanium alloys, Ti6Al7Nb and Ti6Al4V, was performed, and the resulting anodic oxides were studied. The biomedical alloys were made by Laser Engineered Net Shaping. The glycol-based and glycerol-based electrolytes with 0.3 M ammonium fluoride and 2 wt % of deionized water content were tested. It was found that electrolyte type as well as the chemical composition of the base substrate affected the final morphology and chemical composition of the anodic oxide formed. A higher current density, ionic mobility, and oxide growth rate were obtained in glycol-based electrolyte as compared to those obtained in glycerol-based electrolyte for all tested alloys. A self-organized nanotubular and nanoporous morphology of the anodic oxide in both types of electrolyte was obtained. In each electrolyte, the alloy susceptibility to oxidation increased in the following order: Ti6Al4V < Ti 99.5% < Ti6Al7Nb, which can be correlated to the oxidation susceptibility of the base titanium alloy. It was observed that the more impurities/alloying elements in the substrate, the lower the pore diameters of anodic oxide. There was a higher observed incorporation of electrolyte species into the anodic oxide matrix in the glycerol-based electrolyte compared with that in glycol-based electrolyte. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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