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13 pages, 10832 KiB

Open AccessArticle

ZnO:CuO Composites Obtained by Rapid Joule Heating for Photocatalysis

by Adrián Fernández-Calzado, Aarón Calvo-Villoslada, Paloma Fernández and Belén Sotillo

Materials 2024, 17(14), 3502; https://doi.org/10.3390/ma17143502 - 15 Jul 2024

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Abstract

Semiconductor oxides belonging to various families are ideal candidates for application in photocatalytic processes. One of the challenges facing photocatalytic processes today is improving their efficiency under sunlight irradiation. In this study, the growth and characterization of semiconductor oxide nanostructures and composites based [...] Read more.

Semiconductor oxides belonging to various families are ideal candidates for application in photocatalytic processes. One of the challenges facing photocatalytic processes today is improving their efficiency under sunlight irradiation. In this study, the growth and characterization of semiconductor oxide nanostructures and composites based on the ZnO and CuO families are proposed. The selected growth method is the resistive heating of Zn and Cu wires to produce the corresponding oxides, combined with galvanic corrosion of Zn. An exhaustive characterization of the materials obtained has been carried out using techniques based on scanning electron microscopy and optical spectroscopies. The method we have followed and the conditions used in this study present promising results, not only from a degradation efficiency point of view but also because it is a cheap, easy, and fast growth method. These characteristics are essential in order to scale the process beyond the laboratory. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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18 pages, 5333 KiB

Open AccessArticle

Fenton-like Degradation of Methylene Blue on Attapulgite Clay Composite by Loading of Iron–Oxide: Eco-Friendly Preparation and Its Catalytic Activity

by Naveed Karim, Tin Kyawoo, Chao Jiang, Saeed Ahmed, Weiliang Tian, Huiyu Li and Yongjun Feng

Materials 2024, 17(11), 2615; https://doi.org/10.3390/ma17112615 - 29 May 2024

Cited by 1 | Viewed by 862

Abstract

The continuous discharge of organic dyes into freshwater resources poses a long-term hazard to aquatic life. The advanced oxidation Fenton process is a combo of adsorption and degradation of pollutants to detoxify toxic effluents, such as anti-bacterial drugs, antibiotics, and organic dyes. In [...] Read more.

The continuous discharge of organic dyes into freshwater resources poses a long-term hazard to aquatic life. The advanced oxidation Fenton process is a combo of adsorption and degradation of pollutants to detoxify toxic effluents, such as anti-bacterial drugs, antibiotics, and organic dyes. In this work, an activated attapulgite clay-loaded iron-oxide (A-ATP@Fe₃O₄) was produced using a two-step reaction, in which attapulgite serves as an enrichment matrix and Fe₃O₄ functions as the active degrading component. The maximum adsorption capacity (q_t) was determined by assessing the effect of temperature, pH H₂O₂, and adsorbent. The results showed that the A-ATP@Fe₃O₄ achieves the highest removal rate of 99.6% under optimum conditions: 40 °C, pH = 3, H₂O₂ 25 mM, and 0.1 g dosage of the composite. The dye removal procedure achieved adsorption and degradation equilibrium in 120 and 30 min, respectively, by following the same processes as the advanced oxidation approach. Catalytic activity, kinetics, and specified surface characteristics suggest that A-ATP@Fe₃O₄ is one of the most promising candidates for advanced oxidation-enrooted removal of organic dyes. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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11 pages, 3602 KiB

Open AccessArticle

Enhanced Catalytic Hydrogenation of Olefins in Sulfur-Rich Naphtha Using Molybdenum Carbide Supported on γ-Al₂O₃ Spheres under Steam Conditions: Simulating the Hot Separator Stream Process

by Hadj Abbas Abbas, Zahra Asgar Pour, Mohammed S. Alnafisah, Pablo Gonzalez Cortes, Mustapha El Hariri El Nokab, Ahmed Elshewy and Khaled O. Sebakhy

Materials 2024, 17(10), 2278; https://doi.org/10.3390/ma17102278 - 11 May 2024

Cited by 1 | Viewed by 1385

Abstract

Spheres comprising 10 wt.% Mo₂C/γ-Al₂O₃, synthesized through the sucrose route, exhibited unprecedented catalytic activity for olefin hydrogenation within an industrial naphtha feedstock that contained 23 wt.% olefins, as determined by supercritical fluid chromatography (SFC). The catalyst demonstrated [...] Read more.

Spheres comprising 10 wt.% Mo₂C/γ-Al₂O₃, synthesized through the sucrose route, exhibited unprecedented catalytic activity for olefin hydrogenation within an industrial naphtha feedstock that contained 23 wt.% olefins, as determined by supercritical fluid chromatography (SFC). The catalyst demonstrated resilience to sulfur, exhibiting no discernible deactivation signs over a tested 96 h operational period. The resultant hydrogenated naphtha from the catalytic process contained only 2.5 wt.% olefins when the reaction was conducted at 280 °C and 3.44 × 10⁶ Pa H₂, subsequently blended with Athabasca bitumen to meet pipeline specifications for oil transportation. Additionally, the carbide catalyst spheres effectively hydrogenated olefins under steam conditions without experiencing any notable hydrogenation in the aromatics. We propose the supported carbide catalyst as a viable alternative to noble metals, serving as a selective agent for olefin elimination from light petroleum distillates in the presence of steam and sulfur, mitigating the formation of gums and deposits during the transportation of diluted bitumen (dilbit) through pipelines. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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19 pages, 10290 KiB

Open AccessArticle

Colloid Mill-Assisted Ultrasonic-Fractional Centrifugal Purification of Low-Grade Attapulgite and Its Modification for Adsorption of Congo Red

by Xingpeng Wang, Chao Jiang, Huiyu Li, Weiliang Tian, Saeed Ahmed and Yongjun Feng

Materials 2024, 17(9), 2034; https://doi.org/10.3390/ma17092034 - 26 Apr 2024

Cited by 1 | Viewed by 1446

Abstract

Attapulgite (APT) is widely used in wastewater treatment due to its exceptional adsorption and colloidal properties, as well as its cost-effectiveness and eco-friendliness. However, low-grade APT generally limits its performance. Here, a colloid mill-assisted ultrasonic-fractional centrifugal purification method was developed to refine low-grade [...] Read more.

Attapulgite (APT) is widely used in wastewater treatment due to its exceptional adsorption and colloidal properties, as well as its cost-effectiveness and eco-friendliness. However, low-grade APT generally limits its performance. Here, a colloid mill-assisted ultrasonic-fractional centrifugal purification method was developed to refine low-grade APT. This process successfully separated and removed impurity minerals such as quartz and dolomite from the raw ore, resulting in a refined APT purity increase from 16.9% to 60% with a specific surface area of 135.5 m²∙g⁻¹. Further modifying of the refined APT was carried out through the hydrothermal method using varying dosages of cetyltrimethylammonium chloride (CTAC), resulting in the production of four different APT adsorbents denoted as QAPT-n (n = CTAC mole number) ranging from 0.5 to 5 mmol. Using Congo red (CR) as the target pollutant, the QAPT-5 sample exhibited the best adsorption capacity with the maximum quantity of 1652.2 mg∙g⁻¹ in a neutral solution at 30 °C due to the highest surface charge (zeta potential = 8.25 mV). Moreover, the QAPT-5 pellets (~2.0 g adsorbent) shaped by the alginate-assisted molding method removed more than 96% of 200 mL aqueous solution containing 200 mg∙L⁻¹ CR and maintained this efficiency in 10 adsorption–elution cycles, which exhibited the promising practical application. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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18 pages, 10945 KiB

Open AccessArticle

Optimizing FeSiCr-Based Soft Magnetic Composites Using the Deionized Water as the Phosphating Solvent

by Xiangdong Li, Hongya Yu, Hongxiang Wang, Tongxin Yuan and Zhongwu Liu

Materials 2024, 17(7), 1631; https://doi.org/10.3390/ma17071631 - 2 Apr 2024

Cited by 1 | Viewed by 1101

Abstract

To prepare a soft magnetic powder core, the magnetic powder surface has to be insulated by phosphating treatment. Organic chemicals such as ethanol and acetone are generally used as solvents for phosphoric acid, which may cause serious environmental problems. This work proposed deionized [...] Read more.

To prepare a soft magnetic powder core, the magnetic powder surface has to be insulated by phosphating treatment. Organic chemicals such as ethanol and acetone are generally used as solvents for phosphoric acid, which may cause serious environmental problems. This work proposed deionized water as the environmentally friendly phosphating solvent for FeSiCr powder. The soft magnetic composites (SMCs) were prepared using phosphoric acid for inorganic coating and modified silicon polymer for organic coating. The effect of different phosphating solvents, including deionized water, ethanol, and acetone, on the structure and magnetic properties of SMCs were investigated. It is found that the solvent affects the phosphating solution’s stability and the phosphoric acid’s ionization. The phosphoric acid is more stable in deionized water than in ethanol and acetone. The phosphating reaction in deionized water is also more stable in deionized water, resulting in a dense phosphate coating on the particle surface. The effects of phosphoric acid concentration and temperature on the magnetic properties of FeSiCr-based SMCs were further studied. With the increase in phosphoric acid concentration and temperature, the magnetic permeability and saturation magnetization of the powder core decrease, and the core loss decreases, followed by an increase. The optimized combination of properties was obtained for the SMCs phosphated with 0.2 wt.% phosphoric acid in deionized water at 35 °C, including a high effective permeability μ_e of 25.7, high quality factor Q of 80.2, low core loss P_cv of 709.5 mW/cm³ measured at 0.05 T @ 100 kHz, and high withstanding voltage of 276 V, due to the formation of uniform and dense insulating coating layers. In addition, the SMCs prepared with phosphated powder show good corrosion resistance. The anti-corrosion properties of the SMCs using deionized water as a phosphating solvent are better than those using ethanol and acetone. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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16 pages, 4306 KiB

Open AccessArticle

Microstructure of Deposits Sprayed by a High Power Torch with Flash Boiling Atomization of High-Concentration Suspensions

by Saeid Amrollahy Biouki, Fadhel Ben Ettouil, Andre C. Liberati, Ali Dolatabadi and Christian Moreau

Materials 2024, 17(7), 1493; https://doi.org/10.3390/ma17071493 - 25 Mar 2024

Viewed by 795

Abstract

The main objective of this study was to use flash boiling atomization as a new method to inject suspensions with high solid content into the high-power plasma flow. The water-based suspension was prepared with submicron titanium oxide particles with an average size of [...] Read more.

The main objective of this study was to use flash boiling atomization as a new method to inject suspensions with high solid content into the high-power plasma flow. The water-based suspension was prepared with submicron titanium oxide particles with an average size of 500 nm. The investigated solid concentrations were 20, 40, 55 and 70 wt%. Two plasma torches operated at 33, 70 and 110 kW were used to investigate the effect of increasing power on the deposited microstructure and deposition efficiency. At low torch power, the deposition efficiency decreased with increasing solid concentration, and deposits with a high number of unmelted particles were obtained with 70 wt% suspensions. At high torch power, the deposition efficiency increased with increasing solid concentration, and dense deposits were obtained with 70 wt% suspensions. XRD analysis was performed on all deposits to determine the distribution of rutile and anatase phases. The percentage of the anatase phase varied from 35.7% to 66.9%, depending on the power input and solid concentration. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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12 pages, 7626 KiB

Open AccessCommunication

Enhancing Microstructural and Mechanical Properties of Ferrous Medium-Entropy Alloy through Cu Addition and Post-Weld Heat Treatment in Gas Tungsten Arc Welding

by Seonghoon Yoo, Yoona Lee, Myeonghawn Choi, Hyunbin Nam, Sangyong Nam and Namhyun Kang

Materials 2024, 17(1), 181; https://doi.org/10.3390/ma17010181 - 28 Dec 2023

Cited by 1 | Viewed by 1077

Abstract

This study investigates the impact of a high-entropy alloy filler metal coated with copper (Cu) and post-weld heat treatment (PWHT) on the weldability of a ferrous medium-entropy alloy (MEA) in gas tungsten arc welding. The addition of 1-at% Cu had an insignificant effect [...] Read more.

This study investigates the impact of a high-entropy alloy filler metal coated with copper (Cu) and post-weld heat treatment (PWHT) on the weldability of a ferrous medium-entropy alloy (MEA) in gas tungsten arc welding. The addition of 1-at% Cu had an insignificant effect on the microstructural behaviour, despite a positive mixing enthalpy with other elements. It was observed that a small amount of Cu was insufficient to induce phase separation into the Cu-rich phase and refine the microstructure of the as-welded specimen. However, with an increase in the PWHT temperature, the tensile strength remained mostly consistent, while the elongation significantly increased (elongation of as welded, PWHT700, PWHT800, and PWHT 900 were 19, 43, 55 and 68%, respectively). Notably, the PWHT temperature of 900 °C yielded the most desirable results by shifting the fracture location from the coarse-grained heat-affected zone (CGHAZ) to base metal (BM). This was due to significant recrystallisation and homogenised hardness of the cold-rolled BM during PWHT. However, the CGHAZ with coarse grains induced by the welding heat input remained invariant during the PWHT. This study proposes a viable PHWT temperature (900 °C) for enhancing the weldability of cold-rolled ferrous MEA without additional process. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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17 pages, 9463 KiB

Open AccessArticle

Frequency Response Evaluation as Diagnostic and Optimization Tool for Pulsed Unipolar Plasma Electrolytic Oxidation Process and Resultant Coatings on Zirconium

by Evgeny Parfenov, Ruzil Farrakhov, Veta Aubakirova, Andrey Stotskiy, Rameshbabu Nagumothu and Aleksey Yerokhin

Materials 2023, 16(24), 7681; https://doi.org/10.3390/ma16247681 - 17 Dec 2023

Cited by 1 | Viewed by 1073

Abstract

This study aims to bridge various diagnostic tools for the development of smart plasma electrolytic oxidation (PEO) technologies. PEO treatments of commercially pure Zr were carried out using the pulsed unipolar polarisation (PUP) regime with frequency sweep in an alkaline phosphate-silicate electrolyte. Methods [...] Read more.

This study aims to bridge various diagnostic tools for the development of smart plasma electrolytic oxidation (PEO) technologies. PEO treatments of commercially pure Zr were carried out using the pulsed unipolar polarisation (PUP) regime with frequency sweep in an alkaline phosphate-silicate electrolyte. Methods of in situ impedance spectroscopy and electrical transient analysis were used for the process diagnostics under the video imaging of the PEO. Two cutoff frequencies, 170–190 Hz and 620–650 Hz, were identified for the PEO-assisted charge transfer process. An equivalent circuit for the metal–oxide–electrolyte system under PUP PEO conditions was developed; from the capacitance values, two geometrical dielectric barriers were evaluated: a thinner 0.5–1 µm inner layer of the coating and a thicker 4–6 µm outer layer. These estimates were in agreement with the coating cross-sectional morphology. Based on comparing the results obtained using different techniques, the frequencies at which the uniform coatings with the best protective properties were formed were identified. For the selected electrolyte system and polarisation regime, these frequencies ranged from 2 to 5 kHz where the overall circuit reactance was minimal; therefore, the power factor was as close to one as possible. This opens the possibilities for the optimization of the pulsed PEO process and online control of unobservable surface characteristics, e.g., the thickness of the coating layers, thus contributing towards the development of smart PEO technologies. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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26 pages, 6354 KiB

Open AccessArticle

An Analysis of the Performance and Comfort Properties of Fire-Protective Material by Using Inherently Fire-Retardant Fibers and Knitting Structures

by Awais Ahmad Khan, Hafsa Jamshaid, Rajesh Kumar Mishra, Vijay Chandan, Viktor Kolář, Petr Jirků, Miroslav Müller, Shabnam Nazari, Tatiana Alexiou Ivanova and Tanveer Hussain

Materials 2023, 16(23), 7347; https://doi.org/10.3390/ma16237347 - 25 Nov 2023

Viewed by 1483

Abstract

This paper investigates the development of fabric materials using several blends of inherently fire-resistant (FR) fibers and various knitted structures. The samples are evaluated with respect to their performance and comfort-related properties. Inherently fire-resistant fibers, e.g., Nomex, Protex, carbon and FR viscose, were [...] Read more.

This paper investigates the development of fabric materials using several blends of inherently fire-resistant (FR) fibers and various knitted structures. The samples are evaluated with respect to their performance and comfort-related properties. Inherently fire-resistant fibers, e.g., Nomex, Protex, carbon and FR viscose, were used to develop different structures of knitted fabrics. Cross-miss, cross-relief, and vertical tubular structures were knitted by using optimum fiber blend proportions and combinations of stitches. Several important aspects of the fabric samples were investigated, e.g., their physical, mechanical and serviceability performance. Thermo-physiological and tactile/touch-related comfort properties were evaluated in addition to flame resistance performance. An analysis of mechanical performance indicated that the knitted structure has a significant influence on the tensile strength, bursting strength and pilling resistance. The cross-relief structure proved to be the strongest followed by the cross-miss and vertical tubular structures. The FR station suits made from 70:30 Protex/Nomex exhibited the best combination of tensile and bursting strength; therefore, this material is recommended for making a stable and durable station suit. Interestingly, it was also concluded from the experimental study that knitted samples with a cross-relief structure exhibit the best fire-resistance performance. Fiber blends of 70:30 Protex/Nomex and 70:30 Nomex/carbon were found to be optimum in terms of overall performance. The best flame resistance was achieved with Nomex:carbon fiber blends. These results were confirmed with vertical flammability tests, TGA, DTGA and cone calorimetry analysis. The optimization of blend composition as well as knitting structure/architecture is a crucial finding toward designing the best FR station suit in terms of mechanical, dimensional, thermal, thermo-physiological and flame resistance performance. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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25 pages, 6240 KiB

Open AccessArticle

Improved Dimethyl Ether Production from Syngas over Aerogel Sulfated Zirconia and Cu-ZnO(Al) Bifunctional Composite Catalysts

by Hela Lassoued, Noelia Mota, Elena Millán Ordóñez, Sahar Raissi, Mohamed Kadri Younes, Carlos Quilis Romero and Rufino M. Navarro Yerga

Materials 2023, 16(23), 7328; https://doi.org/10.3390/ma16237328 - 24 Nov 2023

Cited by 2 | Viewed by 1236

Abstract

This work is dedicated to the study of the effect of the synthesis conditions (drying and calcination) of sulfated zirconia on the final catalytic behavior of bifunctional composite catalysts prepared by the physical mixing of the sulfated zirconia (methanol dehydration catalyst) with Cu/ZnO/Al [...] Read more.

This work is dedicated to the study of the effect of the synthesis conditions (drying and calcination) of sulfated zirconia on the final catalytic behavior of bifunctional composite catalysts prepared by the physical mixing of the sulfated zirconia (methanol dehydration catalyst) with Cu/ZnO/Al₂O₃ (CZA; methanol synthesis catalyst). The main objective was to optimize the CZA-ZrO₂/SO₄²⁻ composite catalyst for its use in the direct production of dimethyl ether (DME) from syngas. Sulfated zirconia aerogel (AZS) and xerogel (XZS) were prepared using the sol–gel method using different solvent evacuation conditions and calcination temperatures, while the Cu-ZnO(Al) catalyst was synthesized using the coprecipitation procedure. The effectivity of CZA-ZrO₂/SO₄²⁻ composite catalysts for the direct production of dimethyl ether (DME) from syngas was evaluated in a flow reactor at 250 °C and 30 bar total pressure. The characterization of the sulfated zirconia aerogels and xerogels using different techniques showed that the mesoporous aerogel (AZS_0.5300) exhibited the best textural and acidic properties due to the gel drying under supercritical conditions and calcination at 300 °C. As a result, the composite catalyst CZA-AZS_0.5300 exhibited seven times higher DME production than its xerogel-containing counterpart (364 vs. 52 μmol_DME·min⁻¹·g_cat⁻¹). This was attributed to its well-matched metal surface, mesoporous structure, optimal crystallite size and, most importantly, its higher acidity. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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19 pages, 6922 KiB

Open AccessArticle

Mechanical Properties of the Pt-CNT Composite under Uniaxial Deformation: Tension and Compression

by Ustina I. Yankovaskaya, Elena A. Korznikova, Sofia D. Korpusova and Pavel V. Zakharov

Materials 2023, 16(11), 4140; https://doi.org/10.3390/ma16114140 - 1 Jun 2023

Cited by 4 | Viewed by 1387

Abstract

Composite materials are gaining increasing attention from researchers worldwide due to their ability to offer tailored properties for various technical challenges. One of these promising fields is metal matrix composites, including carbon-reinforced metals and alloys. These materials allow for the reduction of density [...] Read more.

Composite materials are gaining increasing attention from researchers worldwide due to their ability to offer tailored properties for various technical challenges. One of these promising fields is metal matrix composites, including carbon-reinforced metals and alloys. These materials allow for the reduction of density while simultaneously enhancing their functional properties. This study is focused on the Pt-CNT composite, its mechanical characteristics, and structural features under uniaxial deformation depending on temperature and mass fractions of carbon nanotube (CNT). The mechanical behavior of platinum reinforced with carbon nanotubes of diameters varying in the interval 6.62–16.55 Å under uniaxial tension and compression deformation has been studied by the molecular dynamics method. Simulations for tensile and compression deformations have been done for all specimens at different temperatures (viz. 300 K, 500 K, 700 K, 900 K, 1100 K, and 1500 K). The calculated mechanical characteristics allow us to conclude that, compared to pure platinum, the Young’s modulus increased by about 60%. The results indicate that yield and tensile strength values decreases with increase in temperature for all simulation blocks. This increase was due to the inherent high axial rigidity of CNTs. In this work, these characteristics are calculated for the first time for Pt-CNT. It can be concluded that CNTs can be an effective reinforcing material for composites based on a metal matrix under tensile strain. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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18 pages, 12282 KiB

Open AccessArticle

Influence of PEO Electrolyzer Geometry on Current Density Distribution and Resultant Coating Properties on Zr-1Nb Alloy

by Veta Aubakirova, Dmitry Gunderov, Ruzil Farrakhov, Vasily Astanin, Andrey Stotskiy, Arseny Sharipov, Alexey Demin, Leonard Khalilov and Evgeny Parfenov

Materials 2023, 16(9), 3377; https://doi.org/10.3390/ma16093377 - 26 Apr 2023

Cited by 1 | Viewed by 1452

Abstract

This paper is devoted to the study of the current density distribution effect on plasma electrolytic oxidation process and resultant coatings on a Zr-1Nb alloy. The influence of the distance between the plates simultaneously placed into an electrolyzer was evaluated to assess the [...] Read more.

This paper is devoted to the study of the current density distribution effect on plasma electrolytic oxidation process and resultant coatings on a Zr-1Nb alloy. The influence of the distance between the plates simultaneously placed into an electrolyzer was evaluated to assess the throwing power of the PEO process. The current density on the facing surfaces of the plates decreases when the distance between them shrinks. This current density has a notable impact on the resultant PEO coating in terms of the surface morphology parameters and electrochemically evaluated corrosion resistance. The influence of this effect is low on the stages of anodizing and spark discharges (60–120 s of the PEO), and significantly increases on the stage of microarc discharges (120–360 s of the PEO). The coating obtained with a smaller distance between the plates, while having the same coating thickness as the others, exhibits higher wear resistance. New correlations between the current density, diffusion coefficient, time constant of nucleation and the coating thickness in the middle of the facing samples were established; in addition, a correlation of the coating morphology in this area with the roughness parameters RPc, RSm was shown. This study contributes to the development of optimized PEO processes for the simultaneously coated several devices of complex shape, e.g., orthopedic implants. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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24 pages, 13320 KiB

Open AccessArticle

The Effect of Smart PEO-Coatings Impregnated with Corrosion Inhibitors on the Protective Properties of AlMg3 Aluminum Alloy

by Andrey S. Gnedenkov, Yana I. Kononenko, Sergey L. Sinebryukhov, Valeriia S. Filonina, Igor E. Vyaliy, Alexey D. Nomerovskii, Alexander Yu. Ustinov and Sergey V. Gnedenkov

Materials 2023, 16(6), 2215; https://doi.org/10.3390/ma16062215 - 9 Mar 2023

Cited by 23 | Viewed by 2262

Abstract

The protective coating with a self-organized microtubular structure was formed using plasma electrolytic oxidation (PEO) on AlMg3 aluminum alloy in the tartrate-fluoride electrolyte. This protective layer was further modified using corrosion inhibitors of the azole group (1,2,4-triazole, benzotriazole) and polymer material (polyvinilidene fluoride, [...] Read more.

The protective coating with a self-organized microtubular structure was formed using plasma electrolytic oxidation (PEO) on AlMg3 aluminum alloy in the tartrate-fluoride electrolyte. This protective layer was further modified using corrosion inhibitors of the azole group (1,2,4-triazole, benzotriazole) and polymer material (polyvinilidene fluoride, PVDF). X-ray diffraction analysis and scanning electron microscopy with energy dispersive spectroscopy were used to study the morphology and composition of the obtained oxide coatings. The presence of the inhibitor in the PEO-layer was confirmed using micro-Raman spectroscopy and X-ray photoelectron spectroscopy. The level of corrosion protection of formed coatings as well as the effect of loaded inhibitors on the anticorrosion efficiency was evaluated using electrochemical impedance spectroscopy (EIS) and localized scanning techniques (SVET/SIET). The coating impregnation with corrosion inhibitors of the azole group significantly improves the corrosion characteristics of the material. Impregnation of the base PEO-layer with 1,2,4-triazole during 24 h results in a 36 times increase in the impedance modulus measured at the lowest frequency (|Z|_f_=0.1Hz). Additional sealing of impregnated coating with polymer improves the corrosion stability of the treated material. On the base of the obtained data, the optimal way of protective inhibitor- and polymer-containing formation using surface treatment was suggested. The best barrier properties were established for hybrid coatings obtained by the immersion of a PEO-coated sample in 1,2,4-triazole solution for 24 h and following spraying the PVDF solution. The value of |Z|_f_=0.1Hz for this protective layer increased by more than two orders of magnitude in comparison with the base PEO-layer. The three-stage mechanism of corrosion inhibition of the sample with smart inhibitor-containing coating was established. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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17 pages, 9130 KiB

Open AccessArticle

Effect of High-Pressure Torsion and Annealing on the Structure, Phase Composition, and Microhardness of the Ti-18Zr-15Nb (at. %) Alloy

by Dmitry Gunderov, Karina Kim, Sofia Gunderova, Anna Churakova, Yuri Lebedev, Ruslan Nafikov, Mikhail Derkach, Konstantin Lukashevich, Vadim Sheremetyev and Sergey Prokoshkin

Materials 2023, 16(4), 1754; https://doi.org/10.3390/ma16041754 - 20 Feb 2023

Cited by 6 | Viewed by 1734

Abstract

The Ti-18Zr-15Nb shape memory alloys are a new material for medical implants. The regularities of phase transformations during heating of this alloy in the coarse-grained quenched state and the nanostructured state after high-pressure torsion have been studied. The specimens in quenched state (Q) [...] Read more.

The Ti-18Zr-15Nb shape memory alloys are a new material for medical implants. The regularities of phase transformations during heating of this alloy in the coarse-grained quenched state and the nanostructured state after high-pressure torsion have been studied. The specimens in quenched state (Q) and HPT state were annealed at 300–550 °C for 0.5, 3, and 12 h. The α-phase formation in Ti-18Zr-15Nb alloy occurs by C-shaped kinetics with a pronounced peak near 400–450 °C for Q state and near 350–450 °C for HPT state, and stops or slows down at higher and lower annealing temperatures. The formation of a nanostructured state in the Ti-18Zr-15Nb alloy as a result of HPT suppresses the β→ω phase transformation during low-temperature annealing (300–350 °C), but activates the β→α phase transformation. In the Q-state the α-phase during annealing at 450–500 °C is formed in the form of plates with a length of tens of microns. The α-phase formed during annealing of nanostructured specimens has the appearance of nanosized particle-grains of predominantly equiaxed shape, distributed between the nanograins of β-phase. The changes in microhardness during annealing of Q-specimens correlate with changes in phase composition during aging. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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19 pages, 10661 KiB

Open AccessArticle

Sustainable Packaging Design for Molded Expanded Polystyrene Cushion

by Normah Kassim, Shayfull Zamree Abd Rahim, Wan Abd Rahman Assyahid Wan Ibrahim, Norshah Afizi Shuaib, Irfan Abd Rahim, Norizah Abd Karim, Andrei Victor Sandu, Maria Pop, Aurel Mihail Titu, Katarzyna Błoch and Marcin Nabiałek

Materials 2023, 16(4), 1723; https://doi.org/10.3390/ma16041723 - 19 Feb 2023

Cited by 3 | Viewed by 3023

Abstract

A molded expanded polystyrene (EPS) cushion is a flexible, closed-cell foam that can be molded to fit any packing application and is effective at absorbing shock. However, the packaging waste of EPS cushions causes pollution to landfills and the environment. Despite being known [...] Read more.

A molded expanded polystyrene (EPS) cushion is a flexible, closed-cell foam that can be molded to fit any packing application and is effective at absorbing shock. However, the packaging waste of EPS cushions causes pollution to landfills and the environment. Despite being known to cause pollution, this sustainable packaging actually has the potential to reduce this environmental pollution because of its reusability. Therefore, the objective of this study is to identify the accurate design parameter that can be emphasized in producing a sustainable design of EPS cushion packaging. An experimental method of drop testing and design simulation analysis was conducted. The effectiveness of the design parameters was also verified. Based on the results, there are four main elements that necessitate careful consideration: rib positioning, EPS cushion thickness, package layout, and packing size. These parameter findings make a significant contribution to sustainable design, where these elements were integrated directly to reduce and reuse packaging material. Thus, it has been concluded that 48 percent of the development cost of the cushion was decreased, 25 percent of mold modification time was significantly saved, and 27 percent of carbon dioxide (CO₂) reduction was identified. The findings also aided in the development of productive packaging design, in which these design elements were beneficial to reduce environmental impact. These findings had a significant impact on the manufacturing industry in terms of the economics and time of the molded expanded polystyrene packaging development. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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21 pages, 9022 KiB

Open AccessArticle

Near-Infrared (NIR) Silver Sulfide (Ag₂S) Semiconductor Photocatalyst Film for Degradation of Methylene Blue Solution

by Zahrah Ramadlan Mubarokah, Norsuria Mahmed, Mohd Natashah Norizan, Ili Salwani Mohamad, Mohd Mustafa Al Bakri Abdullah, Katarzyna Błoch, Marcin Nabiałek, Madalina Simona Baltatu, Andrei Victor Sandu and Petrica Vizureanu

Materials 2023, 16(1), 437; https://doi.org/10.3390/ma16010437 - 3 Jan 2023

Cited by 4 | Viewed by 2719

Abstract

A silver sulfide (Ag₂S) semiconductor photocatalyst film has been successfully synthesized using a solution casting method. To produce the photocatalyst films, two types of Ag₂S powder were used: a commercialized and synthesized powder. For the commercialized powder (CF/comAg₂ [...] Read more.

A silver sulfide (Ag₂S) semiconductor photocatalyst film has been successfully synthesized using a solution casting method. To produce the photocatalyst films, two types of Ag₂S powder were used: a commercialized and synthesized powder. For the commercialized powder (CF/comAg₂S), the Ag₂S underwent a rarefaction process to reduce its crystallite size from 52 nm to 10 nm, followed by incorporation into microcrystalline cellulose using a solution casting method under the presence of an alkaline/urea solution. A similar process was applied to the synthesized Ag₂S powder (CF/syntAg₂S), resulting from the co-precipitation process of silver nitrate (AgNO₃) and thiourea. The prepared photocatalyst films and their photocatalytic efficiency were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-visible spectroscopy (UV-Vis). The results showed that the incorporation of the Ag₂S powder into the cellulose films could reduce the peak intensity of the oxygen-containing functional group, which indicated the formation of a composite film. The study of the crystal structure confirmed that all of the as-prepared samples featured a monoclinic acanthite Ag₂S structure with space group P₂₁/C. It was found that the degradation rate of the methylene blue dye reached 100% within 2 h under sunlight exposure when using CF/comAg₂S and 98.6% for the CF/syntAg₂S photocatalyst film, and only 48.1% for the bare Ag₂S powder. For the non-exposure sunlight samples, the degradation rate of only 33–35% indicated the importance of the semiconductor near-infrared (NIR) Ag₂S photocatalyst used. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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14 pages, 6414 KiB

Open AccessArticle

Effectiveness of Dimple Microtextured Copper Substrate on Performance of Sn-0.7Cu Solder Alloy

by Siti Faqihah Roduan, Juyana A. Wahab, Mohd Arif Anuar Mohd Salleh, Nurul Aida Husna Mohd Mahayuddin, Mohd Mustafa Al Bakri Abdullah, Aiman Bin Mohd Halil, Amira Qistina Syamimi Zaifuddin, Mahadzir Ishak Muhammad, Andrei Victor Sandu, Mădălina Simona Baltatu and Petrica Vizureanu

Materials 2023, 16(1), 96; https://doi.org/10.3390/ma16010096 - 22 Dec 2022

Cited by 1 | Viewed by 1728

Abstract

This paper elucidates the influence of dimple-microtextured copper substrate on the performance of Sn-0.7Cu solder alloy. A dimple with a diameter of 50 µm was produced by varying the dimple depth using different laser scanning repetitions, while the dimple spacing was fixed for [...] Read more.

This paper elucidates the influence of dimple-microtextured copper substrate on the performance of Sn-0.7Cu solder alloy. A dimple with a diameter of 50 µm was produced by varying the dimple depth using different laser scanning repetitions, while the dimple spacing was fixed for each sample at 100 µm. The dimple-microtextured copper substrate was joined with Sn-0.7Cu solder alloy using the reflow soldering process. The solder joints’ wettability, microstructure, and growth of its intermetallic compound (IMC) layer were analysed to determine the influence of the dimple-microtextured copper substrate on the performance of the Sn-0.7Cu solder alloy. It was observed that increasing laser scan repetitions increased the dimples’ depth, resulting in higher surface roughness. In terms of soldering performance, it was seen that the solder joints’ average contact angle decreased with increasing dimple depth, while the average IMC thickness increased as the dimple depth increased. The copper element was more evenly distributed for the dimple-micro-textured copper substrate than its non-textured counterpart. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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20 pages, 10550 KiB

Open AccessArticle

Influence of Polyformaldehyde Monofilament Fiber on the Engineering Properties of Foamed Concrete

by Md Azree Othuman Mydin, Mohd Mustafa Al Bakri Abdullah, Mohd Nasrun Mohd Nawi, Zarina Yahya, Liyana Ahmad Sofri, Madalina Simona Baltatu, Andrei Victor Sandu and Petrica Vizureanu

Materials 2022, 15(24), 8984; https://doi.org/10.3390/ma15248984 - 15 Dec 2022

Cited by 4 | Viewed by 1440

Abstract

Foamed concrete is considered a green building material, which is porous in nature. As a result, it poses benefits such as being light in self-weight, and also has excellent thermal insulation properties, environmental safeguards, good fire resistance performance, and low cost. Nevertheless, foamed [...] Read more.

Foamed concrete is considered a green building material, which is porous in nature. As a result, it poses benefits such as being light in self-weight, and also has excellent thermal insulation properties, environmental safeguards, good fire resistance performance, and low cost. Nevertheless, foamed concrete has several disadvantages such as low strength, a large amount of entrained air, poor toughness, and being a brittle material, all of which has restricted its usage in engineering and building construction. Hence, this study intends to assess the potential utilization of polypropylene fibrillated fiber (PFF) in foamed concrete to enhance its engineering properties. A total of 10 mixes of 600 and 1200 kg/m³ densities were produced by the insertion of four varying percentages of PFF (1%, 2%, 3%, and 4%). The properties assessed were splitting tensile, compressive and flexural strengths, workability, porosity, water absorption, and density. Furthermore, the correlations between the properties considered were also evaluated. The outcomes reveal that the foamed concrete mix with 4% PFF attained the highest porosity, with approximately 13.9% and 15.9% for 600 and 1200 kg/m³ densities in comparison to the control specimen. Besides, the mechanical properties (splitting tensile, compressive and flexural strengths) increased steadily with the increase in the PFF percentages up to the optimum level of 3%. Beyond 3%, the strengths reduced significantly due to poor PFF dispersal in the matrix, leading to a balling effect which causes a degraded impact of scattering the stress from the foamed concrete vicinity to another area of the PFF surface. This exploratory investigation will result in a greater comprehension of the possible applications of PFF in LFC. It is crucial to promote the sustainable development and implementation of LFC materials and infrastructures. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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Review

Jump to: Research

25 pages, 2166 KiB

Open AccessReview

Using RAFT Polymerization Methodologies to Create Branched and Nanogel-Type Copolymers

by Athanasios Skandalis, Theodore Sentoukas, Dimitrios Selianitis, Anastasia Balafouti and Stergios Pispas

Materials 2024, 17(9), 1947; https://doi.org/10.3390/ma17091947 - 23 Apr 2024

Cited by 4 | Viewed by 1600

Abstract

This review aims to highlight the most recent advances in the field of the synthesis of branched copolymers and nanogels using reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerization is a reversible deactivation radical polymerization technique (RDRP) that has gained tremendous attention due [...] Read more.

This review aims to highlight the most recent advances in the field of the synthesis of branched copolymers and nanogels using reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerization is a reversible deactivation radical polymerization technique (RDRP) that has gained tremendous attention due to its versatility, compatibility with a plethora of functional monomers, and mild polymerization conditions. These parameters lead to final polymers with good control over the molar mass and narrow molar mass distributions. Branched polymers can be defined as the incorporation of secondary polymer chains to a primary backbone, resulting in a wide range of complex macromolecular architectures, like star-shaped, graft, and hyperbranched polymers and nanogels. These subcategories will be discussed in detail in this review in terms of synthesis routes and properties, mainly in solutions. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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30 pages, 7656 KiB

Open AccessReview

Plasma Electrolytic Modification of Zirconium and Its Alloys: Brief Review

by Boris L. Krit, Andrey V. Apelfeld, Anatoly M. Borisov, Natalia V. Morozova, Alexander G. Rakoch, Igor V. Suminov and Sergey N. Grigoriev

Materials 2023, 16(16), 5543; https://doi.org/10.3390/ma16165543 - 9 Aug 2023

Cited by 3 | Viewed by 1149

Abstract

The review focuses on the surface modification of Zr and its alloys, which is necessary to expand the applications of these kinds of materials. Data on the properties of pure zirconium and its alloys are presented. Since surface engineering and the operation of [...] Read more.

The review focuses on the surface modification of Zr and its alloys, which is necessary to expand the applications of these kinds of materials. Data on the properties of pure zirconium and its alloys are presented. Since surface engineering and the operation of the above materials are in most cases associated with the formation of oxide coatings, information on the characteristics of ZrO₂ is given. In addition, attention is paid to phasing in the zirconium–oxygen system. It is noted that the most effective method of surface engineering of Zr and its alloys is plasma electrolytic modification (PEM) technology. Specific examples and modes of modification are described, and the reached results are analyzed. The relevance, novelty and originality of the review are determined by the insufficient knowledge about a number of practical features concerning the formation of functional oxide coatings on Zr and some of its alloys by the technology of PEM. In particular, the information on the phase composition and possibilities of stabilization of the tetragonal and cubic modifications of ZrO₂, the effects of the component composition of electrolyte solutions and electrolyte suspensions, and the specifics of the treatment of additive shaping and deformed materials are rather contradictory. This review aims to collect recent advances and provide insights into the trends in the modification of Zr and its alloys, promote the formulation of practical recommendations and assess the development prospects. Full article

(This article belongs to the Special Issue Design and Applications of Functional Materials, Volume II)

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