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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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34 pages, 2112 KB  
Review
Nanotechnology Applied to Cellulosic Materials
by Ana Fernandes, Luísa Cruz-Lopes, Bruno Esteves and Dmitry Evtuguin
Materials 2023, 16(8), 3104; https://doi.org/10.3390/ma16083104 - 14 Apr 2023
Cited by 35 | Viewed by 7185
Abstract
In recent years, nanocellulosic materials have attracted special attention because of their performance in different advanced applications, biodegradability, availability, and biocompatibility. Nanocellulosic materials can assume three distinct morphologies, including cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial cellulose (BC). This review consists of [...] Read more.
In recent years, nanocellulosic materials have attracted special attention because of their performance in different advanced applications, biodegradability, availability, and biocompatibility. Nanocellulosic materials can assume three distinct morphologies, including cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial cellulose (BC). This review consists of two main parts related to obtaining and applying nanocelluloses in advanced materials. In the first part, the mechanical, chemical, and enzymatic treatments necessary for the production of nanocelluloses are discussed. Among chemical pretreatments, the most common approaches are described, such as acid- and alkali-catalyzed organosolvation, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, ammonium persulfate (APS) and sodium persulfate (SPS) oxidative treatments, ozone, extraction with ionic liquids, and acid hydrolysis. As for mechanical/physical treatments, methods reviewed include refining, high-pressure homogenization, microfluidization, grinding, cryogenic crushing, steam blasting, ultrasound, extrusion, aqueous counter collision, and electrospinning. The application of nanocellulose focused, in particular, on triboelectric nanogenerators (TENGs) with CNC, CNF, and BC. With the development of TENGs, an unparalleled revolution is expected; there will be self-powered sensors, wearable and implantable electronic components, and a series of other innovative applications. In the future new era of TENGs, nanocellulose will certainly be a promising material in their constitution. Full article
(This article belongs to the Special Issue Application of Natural Polymers in Bio-Based Products)
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18 pages, 7297 KB  
Article
Molecular Understanding of the Interfacial Interaction and Corrosion Resistance between Epoxy Adhesive and Metallic Oxides on Galvanized Steel
by Shuangshuang Li, Yanliang Zhao, Hailang Wan, Jianping Lin and Junying Min
Materials 2023, 16(8), 3061; https://doi.org/10.3390/ma16083061 - 13 Apr 2023
Cited by 6 | Viewed by 2974
Abstract
The epoxy adhesive-galvanized steel adhesive structure has been widely used in various industrial fields, but achieving high bonding strength and corrosion resistance is a challenge. This study examined the impact of surface oxides on the interfacial bonding performance of two types of galvanized [...] Read more.
The epoxy adhesive-galvanized steel adhesive structure has been widely used in various industrial fields, but achieving high bonding strength and corrosion resistance is a challenge. This study examined the impact of surface oxides on the interfacial bonding performance of two types of galvanized steel with Zn–Al or Zn–Al–Mg coatings. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis showed that the Zn–Al coating was covered by ZnO and Al2O3, while MgO was additionally found on the Zn–Al–Mg coating. Both coatings exhibited excellent adhesion in dry environments, but after 21 days of water soaking, the Zn–Al–Mg joint demonstrated better corrosion resistance than the Zn–Al joint. Numerical simulations revealed that metallic oxides of ZnO, Al2O3, and MgO had different adsorption preferences for the main components of the adhesive. The adhesion stress at the coating–adhesive interface was mainly due to hydrogen bonds and ionic interactions, and the theoretical adhesion stress of MgO adhesive system was higher than that of ZnO and Al2O3. The corrosion resistance of the Zn–Al–Mg adhesive interface was mainly due to the stronger corrosion resistance of the coating itself, and the lower water-related hydrogen bond content at the MgO adhesive interface. Understanding these bonding mechanisms can lead to the development of improved adhesive-galvanized steel structures with enhanced corrosion resistance. Full article
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42 pages, 21104 KB  
Review
Principles and Applications of Resonance Energy Transfer Involving Noble Metallic Nanoparticles
by Zhicong He, Fang Li, Pei Zuo and Hong Tian
Materials 2023, 16(8), 3083; https://doi.org/10.3390/ma16083083 - 13 Apr 2023
Cited by 18 | Viewed by 3880
Abstract
Over the past several years, resonance energy transfer involving noble metallic nanoparticles has received considerable attention. The aim of this review is to cover advances in resonance energy transfer, widely exploited in biological structures and dynamics. Due to the presence of surface plasmons, [...] Read more.
Over the past several years, resonance energy transfer involving noble metallic nanoparticles has received considerable attention. The aim of this review is to cover advances in resonance energy transfer, widely exploited in biological structures and dynamics. Due to the presence of surface plasmons, strong surface plasmon resonance absorption and local electric field enhancement are generated near noble metallic nanoparticles, and the resulting energy transfer shows potential applications in microlasers, quantum information storage devices and micro-/nanoprocessing. In this review, we present the basic principle of the characteristics of noble metallic nanoparticles, as well as the representative progress in resonance energy transfer involving noble metallic nanoparticles, such as fluorescence resonance energy transfer, nanometal surface energy transfer, plasmon-induced resonance energy transfer, metal-enhanced fluorescence, surface-enhanced Raman scattering and cascade energy transfer. We end this review with an outlook on the development and applications of the transfer process. This will offer theoretical guidance for further optical methods in distance distribution analysis and microscopic detection. Full article
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9 pages, 2520 KB  
Article
Band Gaps and Optical Properties of RENiO3 upon Strain: Combining First-Principles Calculations and Machine Learning
by Xuchang Tang, Zhaokai Luo and Yuanyuan Cui
Materials 2023, 16(8), 3070; https://doi.org/10.3390/ma16083070 - 13 Apr 2023
Cited by 3 | Viewed by 2362
Abstract
Rare earth nickel-based perovskite oxides (RENiO3) have been widely studied over recent decades because of their unique properties. In the synthesis of RENiO3 thin films, a lattice mismatch frequently exists between the substrates and the thin films, [...] Read more.
Rare earth nickel-based perovskite oxides (RENiO3) have been widely studied over recent decades because of their unique properties. In the synthesis of RENiO3 thin films, a lattice mismatch frequently exists between the substrates and the thin films, which may affect the optical properties of RENiO3. In this paper, the first-principles calculations were employed to study the electronic and optical properties of RENiO3 under strain. The results showed that with the increase in tensile strength, the band gap generally shows a widening trend. For optical properties, the absorption coefficients increase with the enhancement of photon energies in the far-infrared range. The compressive strain increases the light absorption, while the tensile strain suppresses it. For the reflectivity spectrum in the far-infrared range, a minimum reflectivity displays around the photon energy of 0.3 eV. The tensile strain enhances the reflectivity in the range of 0.05–0.3 eV, whereas it decreases it when the photon energies are larger than 0.3 eV. Furthermore, machine learning algorithms were applied and found that the planar epitaxial strain, electronegativity, volume of supercells, and rare earth element ion radius play key roles in the band gaps. Photon energy, electronegativity, band gap, the ionic radius of the rare earth element, and the tolerance factor are key parameters significantly influencing the optical properties. Full article
(This article belongs to the Section Materials Simulation and Design)
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13 pages, 8894 KB  
Article
Biocomposite Foams with Multimodal Cellular Structures Based on Cork Granulates and Microwave Processed Egg White Proteins
by Giorgio Luciano, Adriano Vignali, Maurizio Vignolo, Roberto Utzeri, Fabio Bertini and Salvatore Iannace
Materials 2023, 16(8), 3063; https://doi.org/10.3390/ma16083063 - 13 Apr 2023
Cited by 4 | Viewed by 2251
Abstract
In an effort to reduce greenhouse gas emission, reduce the consumption of natural resources, and increase the sustainability of biocomposite foams, the present study focuses on the recycling of cork processing waste for the production of lightweight, non-structural, fireproof thermal and acoustic insulating [...] Read more.
In an effort to reduce greenhouse gas emission, reduce the consumption of natural resources, and increase the sustainability of biocomposite foams, the present study focuses on the recycling of cork processing waste for the production of lightweight, non-structural, fireproof thermal and acoustic insulating panels. Egg white proteins (EWP) were used as a matrix model to introduce an open cell structure via a simple and energy-efficient microwave foaming process. Samples with different compositions (ratio of EWP and cork) and additives (eggshells and inorganic intumescent fillers) were prepared with the aim of correlating composition, cellular structures, flame resistance, and mechanical properties. Full article
(This article belongs to the Special Issue Polymer Foams: Materials, Processing and Properties)
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16 pages, 5264 KB  
Article
Lead Zirconate Titanate Transducers Embedded in Composite Laminates: The Influence of the Integration Method on Ultrasound Transduction
by Nina Kergosien, Ludovic Gavérina, Guillemette Ribay, Florence Saffar, Pierre Beauchêne, Olivier Mesnil and Olivier Bareille
Materials 2023, 16(8), 3057; https://doi.org/10.3390/ma16083057 - 12 Apr 2023
Cited by 4 | Viewed by 2421
Abstract
In the context of an embedded structural health monitoring (SHM) system, two methods of transducer integration into the core of a laminate carbon fiber-reinforced polymer (CFRP) are tested: cut-out and between two plies. This study focuses on the effect of integration methods on [...] Read more.
In the context of an embedded structural health monitoring (SHM) system, two methods of transducer integration into the core of a laminate carbon fiber-reinforced polymer (CFRP) are tested: cut-out and between two plies. This study focuses on the effect of integration methods on Lamb wave generation. For this purpose, plates with an embedded lead zirconate titanate (PZT) transducer are cured in an autoclave. The embedded PZT insulation, integrity, and ability to generate Lamb waves are checked with electromechanical impedance, X-rays, and laser Doppler vibrometry (LDV) measurements. Lamb wave dispersion curves are computed by LDV using two-dimensional fast Fourier transform (Bi-FFT) to study the quasi-antisymmetric mode (qA0) excitability in generation with the embedded PZT in the frequency range of 30 to 200 kHz. The embedded PZT is able to generate Lamb waves, which validate the integration procedure. The first minimum frequency of the embedded PZT shifts to lower frequencies and its amplitude is reduced compared to a surface-mounted PZT. Full article
(This article belongs to the Special Issue Organic Matrix Composites and Multifunctional Materials)
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10 pages, 3363 KB  
Article
The Role of GaN in the Heterostructure WS2/GaN for SERS Applications
by Tsung-Shine Ko, En-Ting Lin, Yen-Teng Ho and Chen-An Deng
Materials 2023, 16(8), 3054; https://doi.org/10.3390/ma16083054 - 12 Apr 2023
Cited by 6 | Viewed by 2524
Abstract
In the application of WS2 as a surface–enhanced Raman scattering (SERS) substrate, enhancing the charge transfer (CT) opportunity between WS2 and analyte is an important issue for SERS efficiency. In this study, we deposited few-layer WS2 (2–3 layers) on GaN [...] Read more.
In the application of WS2 as a surface–enhanced Raman scattering (SERS) substrate, enhancing the charge transfer (CT) opportunity between WS2 and analyte is an important issue for SERS efficiency. In this study, we deposited few-layer WS2 (2–3 layers) on GaN and sapphire substrates with different bandgap characteristics to form heterojunctions using a chemical vapor deposition. Compared with sapphire, we found that using GaN as a substrate for WS2 can effectively enhance the SERS signal, with an enhancement factor of 6.45 × 104 and a limit of detection of 5 × 10−6 M for probe molecule Rhodamine 6G according to SERS measurement. Analysis of Raman, Raman mapping, atomic force microscopy, and SERS mechanism revealed that The SERS efficiency increased despite the lower quality of the WS2 films on GaN compared to those on sapphire, as a result of the increased number of transition pathways present in the interface between WS2 and GaN. These carrier transition pathways could increase the opportunity for CT, thus enhancing the SERS signal. The WS2/GaN heterostructure proposed in this study can serve as a reference for enhancing SERS efficiency. Full article
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10 pages, 4494 KB  
Article
Adsorption Tuning of Polarity and Magnetism in AgCr2S4 Monolayer
by Ranran Li, Yu Wang, Ning Ding, Shuai Dong and Ming An
Materials 2023, 16(8), 3058; https://doi.org/10.3390/ma16083058 - 12 Apr 2023
Cited by 5 | Viewed by 2539
Abstract
As a recent successfully exfoliated non-van der Waals layered material, AgCrS2 has received a lot of attention. Motivated by its structure-related magnetic and ferroelectric behavior, a theoretical study on its exfoliated monolayer AgCr2S4 has been carried out in the [...] Read more.
As a recent successfully exfoliated non-van der Waals layered material, AgCrS2 has received a lot of attention. Motivated by its structure-related magnetic and ferroelectric behavior, a theoretical study on its exfoliated monolayer AgCr2S4 has been carried out in the present work. Based on density functional theory, the ground state and magnetic order of monolayer AgCr2S4 have been determined. The centrosymmetry emerges upon two-dimensional confinement and thus eliminates the bulk polarity. Moreover, two-dimensional ferromagnetism appears in the CrS2 layer of AgCr2S4 and can persist up to room temperature. The surface adsorption has also been taken into consideration, which shows a nonmonotonic effect on the ionic conductivity through ion displacement of the interlayer Ag, but has little impact on the layered magnetic structure. Full article
(This article belongs to the Special Issue First-Principles Calculations of 2D Magnetic Materials)
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13 pages, 6704 KB  
Article
Formation of Self-Healing Organic Coatings for Corrosion Protection of Al Alloys by Dispersion of Spherical and Fibrous Capsules
by Makoto Chiba, Yuki Tsuji, Rin Takada, Yuri Eguchi and Hideaki Takahashi
Materials 2023, 16(8), 3018; https://doi.org/10.3390/ma16083018 - 11 Apr 2023
Cited by 5 | Viewed by 5260
Abstract
In previous works, we developed a self-healing organic coating with dispersed spherical capsules for corrosion protection. The capsule consisted of a polyurethane shell and healing agent as the inner. When the coating was damaged physically, the capsules were broken, and the healing agent [...] Read more.
In previous works, we developed a self-healing organic coating with dispersed spherical capsules for corrosion protection. The capsule consisted of a polyurethane shell and healing agent as the inner. When the coating was damaged physically, the capsules were broken, and the healing agent was released from the broken capsules to the damaged area. The healing agent could react with moisture in the air to form the self-healing structure and cover the damaged area of coating. In the present investigation, a self-healing organic coating with spherical and fibrous capsules was formed on aluminum alloys. The corrosion behavior of the specimen coated with the self-healing coating was examined in a Cu2+/Cl solution after physical damage, and it was found that no corrosion occurred during the corrosion test. This is discussed in terms of the high healing ability of fibrous capsules as a result of the high projected area. Full article
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28 pages, 15194 KB  
Article
Potential Utilization of Ground Eggshells as a Biofiller for Natural Rubber Biocomposites
by Anna Sowińska-Baranowska and Magdalena Maciejewska
Materials 2023, 16(8), 2988; https://doi.org/10.3390/ma16082988 - 9 Apr 2023
Cited by 11 | Viewed by 3572
Abstract
The aim of this work was application of ground eggshells in various amounts by weight as a biofiller for natural rubber (NR) biocomposites. Cetyltrimethylammonium bromide (CTAB), ionic liquids (ILs), i.e., 1-butyl-3-methylimidazolium chloride (BmiCl) and 1-decyl-3-methylimidazolium bromide (DmiBr), and silanes, i.e., (3-aminopropyl)-triethoxysilane (APTES) and [...] Read more.
The aim of this work was application of ground eggshells in various amounts by weight as a biofiller for natural rubber (NR) biocomposites. Cetyltrimethylammonium bromide (CTAB), ionic liquids (ILs), i.e., 1-butyl-3-methylimidazolium chloride (BmiCl) and 1-decyl-3-methylimidazolium bromide (DmiBr), and silanes, i.e., (3-aminopropyl)-triethoxysilane (APTES) and bis [3-(triethoxysilyl)propyl] tetrasulfide (TESPTS), were used to increase the activity of ground eggshells in the elastomer matrix and to ameliorate the cure characteristics and properties of NR biocomposites. The influence of ground eggshells, CTAB, ILs, and silanes on the crosslink density, mechanical properties, and thermal stability of NR vulcanizates and their resistance to prolonged thermo-oxidation were explored. The amount of eggshells affected the curing characteristics and crosslink density of the rubber composites and therefore their tensile properties. Vulcanizates filled with eggshells demonstrated higher crosslink density than the unfilled sample by approximately 30%, whereas CTAB and ILs increased the crosslink density by 40–60% compared to the benchmark. Owing to the enhanced crosslink density and uniform dispersion of ground eggshells, vulcanizates containing CTAB and ILs exhibited tensile strength improved by approximately 20% compared to those without these additives. Moreover, the hardness of these vulcanizates was increased by 35–42%. Application of both the biofiller and the tested additives did not significantly affect the thermal stability of cured NR compared to the unfilled benchmark. Most importantly, the eggshell-filled vulcanizates showed improved resistance to thermo-oxidative aging compared to the unfilled NR. Full article
(This article belongs to the Special Issue Advanced Rubber Composites II)
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21 pages, 2579 KB  
Review
Thermal Conductivity of Aluminum Alloys—A Review
by Ailing Zhang and Yanxiang Li
Materials 2023, 16(8), 2972; https://doi.org/10.3390/ma16082972 - 8 Apr 2023
Cited by 126 | Viewed by 20690
Abstract
Aluminum alloys have been extensively used as heatproof and heat-dissipation components in automotive and communication industries, and the demand for aluminum alloys with higher thermal conductivity is increasing. Therefore, this review focuses on the thermal conductivity of aluminum alloys. First, we formulate the [...] Read more.
Aluminum alloys have been extensively used as heatproof and heat-dissipation components in automotive and communication industries, and the demand for aluminum alloys with higher thermal conductivity is increasing. Therefore, this review focuses on the thermal conductivity of aluminum alloys. First, we formulate the theory of thermal conduction of metals and effective medium theory, and then analyze the effect of alloying elements, secondary phases, and temperature on the thermal conductivity of aluminum alloys. Alloying elements are the most crucial factor, whose species, existing states, and mutual interactions significantly affect the thermal conductivity of aluminum. Alloying elements in a solid solution weaken the thermal conductivity of aluminum more dramatically than those in the precipitated state. The characteristics and morphology of secondary phases also affect thermal conductivity. Temperature also affects thermal conductivity by influencing the thermal conduction of electrons and phonons in aluminum alloys. Furthermore, recent studies on the effects of casting, heat treatment, and AM processes on the thermal conductivity of aluminum alloys are summarized, in which processes mainly affect thermal conductivity by varying existing states of alloying elements and the morphology of secondary phases. These analyses and summaries will further promote the industrial design and development of aluminum alloys with high thermal conductivity. Full article
(This article belongs to the Special Issue Structure and Mechanical Properties of Alloys, Volume II)
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16 pages, 48635 KB  
Article
On the Springback and Load in Three-Point Air Bending of the AW-2024 Aluminium Alloy Sheet with AW-1050A Aluminium Cladding
by Stanisław Kut, Grzegorz Pasowicz and Feliks Stachowicz
Materials 2023, 16(8), 2945; https://doi.org/10.3390/ma16082945 - 7 Apr 2023
Cited by 7 | Viewed by 2512
Abstract
This article presents the results of an analysis of the bending load characteristics and the springback phenomenon occurring during three-point bending of 1.0 and 2.0 mm thick AW-2024 aluminium alloy sheets with rolled AW-1050A cladding. A new proprietary equation was proposed for determining [...] Read more.
This article presents the results of an analysis of the bending load characteristics and the springback phenomenon occurring during three-point bending of 1.0 and 2.0 mm thick AW-2024 aluminium alloy sheets with rolled AW-1050A cladding. A new proprietary equation was proposed for determining the bending angle as a function of deflection, which takes into account the influence of the tool radius and the sheet thickness. The experimentally determined springback and bending load characteristics were compared with the results of numerical modelling using different models: Model I, a 2D model for a plane deformation state, disregarding the material properties of the clad layers; Model II, a 2D model for a plane deformation state, taking into account the material properties of the cladding layers; Model III, a 3D shell model with the Huber–von Mises isotropic plasticity condition; Model IV, a 3D shell model with the Hill anisotropic plasticity condition; and Model V, a 3D shell model with the Barlat anisotropic plasticity condition. The effectiveness of these five tested FEM models in predicting the bending load and springback characteristics was demonstrated. Model II was the most effective in predicting bending load, while Model III was the most effective in predicting the amount of springback after bending. Full article
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15 pages, 3810 KB  
Article
Probabilistic Modelling of Fracture Toughness of Composites with Discontinuous Reinforcement
by Grzegorz Mieczkowski, Tadeusz Szymczak, Dariusz Szpica and Andrzej Borawski
Materials 2023, 16(8), 2962; https://doi.org/10.3390/ma16082962 - 7 Apr 2023
Cited by 2 | Viewed by 2011
Abstract
The results presented in the paper are related to the prediction of the effective fracture toughness of particulate composites (KICeff). KICeff was determined using a probabilistic model supported by a cumulative probability function qualitatively following the Weibull [...] Read more.
The results presented in the paper are related to the prediction of the effective fracture toughness of particulate composites (KICeff). KICeff was determined using a probabilistic model supported by a cumulative probability function qualitatively following the Weibull distribution. Using this approach, it was possible to model two-phase composites with an arbitrarily defined volume fraction of each phase. The predicted value of the effective fracture toughness of the composite was determined based on the mechanical parameter of the reinforcement (fracture toughness), matrix (fracture toughness, Young’s modulus, yield stress), and composite (Young’s modulus, yield stress). The proposed method was validated: the determined fracture toughness of the selected composites was in accordance with the experimental data (the authors’ tests and literature data). In addition, the obtained results were compared with data captured by means of the rule of mixtures (ROM). It was found that the prediction of KICeff using the ROM was subject to a significant error. Moreover, a study of the effect of averaging the elastic–plastic parameters of the composite, on KICeff, was performed. The results showed that if the yield stress of the composite increased, a decrease in its fracture toughness was noticed, which is in line with the literature reports. Furthermore, it was noted that an increase in the Young’s modulus of the composite affected KICeff in the same way as a change in its yield stress. Full article
(This article belongs to the Special Issue Methodology of the Design and Testing of Composite Structures)
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20 pages, 9572 KB  
Article
Corrosion Behavior of Nitrided Layer of Ti6Al4V Titanium Alloy by Hollow Cathodic Plasma Source Nitriding
by Lei Zhang, Minghao Shao, Zhehao Zhang, Xuening Yi, Jiwen Yan, Zelong Zhou, Dazhen Fang, Yongyong He and Yang Li
Materials 2023, 16(8), 2961; https://doi.org/10.3390/ma16082961 - 7 Apr 2023
Cited by 12 | Viewed by 3227
Abstract
Ti6Al4V titanium alloys, with high specific strength and good biological compatibility with the human body, are ideal materials for medical surgical implants. However, Ti6Al4V titanium alloys are prone to corrosion in the human environment, which affects the service life of implants and harms [...] Read more.
Ti6Al4V titanium alloys, with high specific strength and good biological compatibility with the human body, are ideal materials for medical surgical implants. However, Ti6Al4V titanium alloys are prone to corrosion in the human environment, which affects the service life of implants and harms human health. In this work, hollow cathode plasm source nitriding (HCPSN) was used to generate nitrided layers on the surfaces of Ti6Al4V titanium alloys to improve their corrosion resistance. Ti6Al4V titanium alloys were nitrided in NH3 at 510 °C for 0, 1, 2, and 4 h. The microstructure and phase composition of the Ti-N nitriding layer was characterized by high-resolution transmission electron microscopy, atomic force microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. This modified layer was identified to be composed of TiN, Ti2N, and α-Ti (N) phase. To study the corrosion properties of different phases, the nitriding 4 h samples were mechanically ground and polished to obtain the various surfaces of Ti2N and α-Ti (N) phases. The potentiodynamic polarization and electrochemical impedance measurements were conducted in Hank’s solution to characterize the corrosion resistance of Ti-N nitriding layers in the human environment. The relationship between corrosion resistance and the microstructure of the Ti-N nitriding layer was discussed. The new Ti-N nitriding layer that can improve corrosion resistance provides a broader prospect for applying Ti6Al4V titanium alloy in the medical field. Full article
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17 pages, 4149 KB  
Article
Sustainable Innovation: Turning Waste into Soil Additives
by Daria Marczak, Krzysztof Lejcuś, Iwona Lejcuś and Jakub Misiewicz
Materials 2023, 16(7), 2900; https://doi.org/10.3390/ma16072900 - 6 Apr 2023
Cited by 10 | Viewed by 2979
Abstract
In recent years, a dynamic increase in environmental pollution with textile waste has been observed. Natural textile waste has great potential for environmental applications. This work identifies potential ways of sustainably managing natural textile waste, which is problematic waste from sheep farming or [...] Read more.
In recent years, a dynamic increase in environmental pollution with textile waste has been observed. Natural textile waste has great potential for environmental applications. This work identifies potential ways of sustainably managing natural textile waste, which is problematic waste from sheep farming or the cultivation of fibrous plants. On the basis of textile waste, an innovative technology was developed to support water saving and plant vegetation- biodegradable water-absorbing geocomposites (BioWAGs). The major objective of this study was to determine BioWAG effectiveness under field conditions. The paper analyses the effect of BioWAGs on the increments in fresh and dry matter, the development of the root system, and the relative water content (RWC) of selected grass species. The conducted research confirmed the high efficiency of the developed technology. The BioWAGs increased the fresh mass of grass shoots by 230-420% and the root system by 130-200% compared with the control group. The study proved that BioWAGs are a highly effective technology that supports plant vegetation and saves water. Thanks to the reuse of waste materials, the developed technology is compatible with the assumptions of the circular economy and the goals of sustainable development. Full article
(This article belongs to the Section Green Materials)
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23 pages, 8504 KB  
Article
Scratch and Wear Behaviour of Co-Cr-Mo Alloy in Ringer’s Lactate Solution
by Raimundo Silva, Marcos Dantas dos Santos, Rui Madureira, Rui Soares, Rui Neto, Ângela Aparecida Vieira, Polyana Alves Radi Gonçalves, Priscila Maria Sarmeiro M. Leite, Lúcia Vieira and Filomena Viana
Materials 2023, 16(7), 2923; https://doi.org/10.3390/ma16072923 - 6 Apr 2023
Cited by 11 | Viewed by 2911
Abstract
Cobalt–chromium–molybdenum (Co-Cr-Mo) alloy is a material recommended for biomedical implants; however, to be suitable for this application, it should have good tribological properties, which are related to grain size. This paper investigates the tribological behaviour of a Co-Cr-Mo alloy produced using investment casting, [...] Read more.
Cobalt–chromium–molybdenum (Co-Cr-Mo) alloy is a material recommended for biomedical implants; however, to be suitable for this application, it should have good tribological properties, which are related to grain size. This paper investigates the tribological behaviour of a Co-Cr-Mo alloy produced using investment casting, together with electromagnetic stirring, to reduce its grain size. The samples were subjected to wear and scratch tests in simulated body fluid (Ringer’s lactate solution). Since a reduction in grain size can influence the behaviour of the material, in terms of resistance and tribological response, four samples with different grain sizes were produced for use in our investigation of the behaviour of the alloy, in which we considered the friction coefficient, wear, and scratch resistance. The experiments were performed using a tribometer, with mean values for the friction coefficient, normal load, and tangential force acquired and recorded by the software. Spheres of Ti-6Al-4V and 316L steel were used as counterface materials. In addition, to elucidate the influence of grain size on the mechanical properties of the alloy, observations were conducted via scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD). The results showed changes in the structure, with a reduction in grain size from 5.51 to 0.79 mm. Using both spheres, the best results for the friction coefficient and wear volume corresponded to the sample with the smallest grain size of 0.79 mm. The friction coefficients obtained were 0.37 and 0.45, using the Ti-6Al-4V and 316L spheres, respectively. These results confirm that the best surface finish for Co-Cr-Mo alloy used as a biomedical implant is one with a smaller grain size, since this results in a lower friction coefficient and low wear. Full article
(This article belongs to the Section Metals and Alloys)
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20 pages, 14100 KB  
Article
Effect of Process Parameters on the Microstructure and Properties of Cu–Cr–Nb–Ti Alloy Manufactured by Selective Laser Melting
by Jian Li, Zuming Liu, Huan Zhou, Shupeng Ye, Yazhou Zhang, Tao Liu, Daoyan Jiang, Lei Chen and Runxing Zhou
Materials 2023, 16(7), 2912; https://doi.org/10.3390/ma16072912 - 6 Apr 2023
Cited by 11 | Viewed by 3111
Abstract
The fabrication of high-performance copper alloys by selective laser melting (SLM) is challenging, and establishing relationships between the process parameters and microstructures is necessary. In this study, Cu–Cr–Nb–Ti alloy is manufactured by SLM, and the microstructures of the alloy are investigated by X-ray [...] Read more.
The fabrication of high-performance copper alloys by selective laser melting (SLM) is challenging, and establishing relationships between the process parameters and microstructures is necessary. In this study, Cu–Cr–Nb–Ti alloy is manufactured by SLM, and the microstructures of the alloy are investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and electron backscatter diffraction (EBSD). The effects of processing parameters such as laser power and scanning speed on the relative density, defects, microstructures, mechanical properties, and electrical conductivity of the Cu–Cr–Nb–Ti alloy are studied. The optimal processing window for fabricating Cu–Cr–Nb–Ti alloy by SLM is determined. Face-centered cubic (FCC) Cu diffraction peaks shifting to small angles are observed, and there are no diffraction peaks related to the second phase. The grains of XY planes have a bimodal distribution with an average grain size of 24–55 μm. Fine second phases with sizes of less than 50 nm are obtained. The microhardness, tensile strength, and elongation of the Cu–Cr–Nb–Ti alloy manufactured using the optimum processing parameters, laser power of 325 W and scanning speed of 800 mm/s, are 139 HV0.2, 416 MPa, and 27.8%, respectively, and the electrical conductivity is 15.6% IACS (International Annealed Copper Standard). This study provides a feasible scheme for preparing copper alloys with excellent performance and complex geometries. Full article
(This article belongs to the Special Issue 3D Printing of Metallic Materials)
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15 pages, 4461 KB  
Article
The Influence of Mg-Impurities in Raw Materials on the Synthesis of Rankinite Clinker and the Strength of Mortar Hardening in CO2 Environment
by Raimundas Siauciunas, Edita Prichockiene and Zenonas Valancius
Materials 2023, 16(7), 2930; https://doi.org/10.3390/ma16072930 - 6 Apr 2023
Cited by 7 | Viewed by 2136
Abstract
The idea of this work is to reduce the negative effect of ordinary Portland cement (OPC) manufacture on the environment by decreasing clinker production temperature and developing an alternative rankinite binder that hardens in the CO2 atmosphere. The common OPC raw materials, [...] Read more.
The idea of this work is to reduce the negative effect of ordinary Portland cement (OPC) manufacture on the environment by decreasing clinker production temperature and developing an alternative rankinite binder that hardens in the CO2 atmosphere. The common OPC raw materials, limestone and mica clay, if they contain a higher MgO content, have been found to be unsuitable for the synthesis of CO2-curing low-lime binders. X-ray diffraction analysis (ex-situ and in-situ in the temperature range of 25–1150 °C) showed that akermanite Ca2Mg(Si2O7) begins to form at a temperature of 900 °C. According to Rietveld refinement, the interlayer distances of the resulting curve are more accurately described by the compound, which contains intercalated Fe2+ and Al3+ ions and has the chemical formula Ca2(MgO0.495·FeO0.202·AlO0.303)·(FeO0.248·AlO·Si1.536·O7). Stoichiometric calculations showed that FeO and Al2O3 have replaced about half of the MgO content in the akermanite structure. All this means that only ~4 wt% MgO content in the raw materials determines that ~60 wt% calcium magnesium silicates are formed in the synthesis product. Moreover, it was found that the formed akermanite practically does not react with CO2. Within 24 h of interaction with 99.9 wt% of CO2 gas (15 bar), the intensity of the akermanite peaks does not practically change at 25 °C; no changes are observed at 45 °C, either, which means that the chemical reaction does not take place. As a result, the compressive strength of the samples compressed from the synthesized product and CEN Standard sand EN 196-1 (1:3), and hardened at 15 bar CO2, 45 °C for 24 h, was only 14.45 MPa, while the analogous samples made from OPC clinker obtained from the same raw materials yielded 67.5 MPa. Full article
(This article belongs to the Special Issue Advances in Sustainable Civil Engineering Materials)
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16 pages, 3865 KB  
Article
Photoacoustic Characterization of TiO2 Thin-Films Deposited on Silicon Substrate Using Neural Networks
by Katarina Lj Djordjević, Dragana K. Markushev, Marica N. Popović, Mioljub V. Nesić, Slobodanka P. Galović, Dragan V. Lukić and Dragan D. Markushev
Materials 2023, 16(7), 2865; https://doi.org/10.3390/ma16072865 - 4 Apr 2023
Cited by 4 | Viewed by 1934
Abstract
In this paper, the possibility of determining the thermal, elastic and geometric characteristics of a thin TiO2 film deposited on a silicon substrate, with a thickness of 30 μm, in the frequency range of 20 to 20 kHz with neural networks were [...] Read more.
In this paper, the possibility of determining the thermal, elastic and geometric characteristics of a thin TiO2 film deposited on a silicon substrate, with a thickness of 30 μm, in the frequency range of 20 to 20 kHz with neural networks were analysed. For this purpose, the geometric (thickness), thermal (thermal diffusivity, coefficient of linear expansion) and electronic parameters of substrates were known and constant in the two-layer model, while the following nano-layer thin-film parameters were changed: thickness, expansion and thermal diffusivity. Predictions of these three parameters of the thin-film were analysed separately with three neural networks. All of them together were joined by a fourth neural network. It was shown that the neural network, which analysed all three parameters at the same time, achieved the highest accuracy, so the use of networks that provide predictions for only one parameter is less reliable. The obtained results showed that the application of neural networks in determining the thermoelastic properties of a thin film on a supporting substrate enables the estimation of its characteristics with great accuracy. Full article
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12 pages, 3387 KB  
Article
Negative Magnetoresistance in Hopping Regime of Lightly Doped Thermoelectric SnSe
by Marija Zorić, Naveen Singh Dhami, Kristian Bader, Peter Gille, Ana Smontara and Petar Popčević
Materials 2023, 16(7), 2863; https://doi.org/10.3390/ma16072863 - 4 Apr 2023
Cited by 1 | Viewed by 2277
Abstract
Semiconducting SnSe, an analog of black phosphorus, recently attracted great scientific interest due to a disputed report of a large thermoelectric figure of merit, which has not been reproduced subsequently. Here we concentrate on the low-temperature ground state. To gain a better understanding [...] Read more.
Semiconducting SnSe, an analog of black phosphorus, recently attracted great scientific interest due to a disputed report of a large thermoelectric figure of merit, which has not been reproduced subsequently. Here we concentrate on the low-temperature ground state. To gain a better understanding of the system, we present magneto-transport properties in high-quality single crystals of as-grown, lightly doped SnSe down to liquid helium temperatures. We show that SnSe behaves as a p-type doped semiconductor in the vicinity of a metal-insulator transition. Electronic transport at the lowest temperatures is dominated by the hopping mechanism. Negative magnetoresistance at low fields is well described by antilocalization, while positive magnetoresistance at higher fields is consistent with the shrinkage of localized impurity wavefunctions. At higher temperatures, a dilute metallic regime is realized where elusive T2 and B2 resistivity dependence is observed, posing a challenge to theoretical comprehension of the underlying physical mechanism. Full article
(This article belongs to the Special Issue New Insights into Metal–Insulator Transitions)
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25 pages, 40744 KB  
Article
A Bond-Based Peridynamic Model with Matrix Plasticity for Impact Damage Analysis of Composite Materials
by Mingwei Sun, Lisheng Liu, Hai Mei, Xin Lai, Xiang Liu and Jing Zhang
Materials 2023, 16(7), 2884; https://doi.org/10.3390/ma16072884 - 4 Apr 2023
Cited by 3 | Viewed by 2282
Abstract
The prediction of damage and failure to fiber-reinforced polymer composites in extreme environments, particularly when subjected to impact loading, is a crucial issue for the application and design of protective structures. In this paper, based on the prototype microelastic brittle (PMB) model and [...] Read more.
The prediction of damage and failure to fiber-reinforced polymer composites in extreme environments, particularly when subjected to impact loading, is a crucial issue for the application and design of protective structures. In this paper, based on the prototype microelastic brittle (PMB) model and the LaRC05 composite materials failure model, we proposed a bond-based peridynamic (BB-PD) model with the introduction of plastic hardening of the resin matrix for fiber-reinforced polymer composites. The PD constitutive relationships of the matrix bond and interlayer bond under compressive loading are considered to include two stages of linear elasticity and plastic hardening, according to the stress–strain relationship of the resin matrix in the LaRC05 failure model. The proposed PD model is employed to simulate the damage behaviors of laminated composites subjected to impact loading. The corresponding ballistic impact tests of composite laminates were carried out to observe their damage behaviors. The PD prediction results are in good agreement with the ballistic experimental results, which can verify the correctness and accuracy of the PD model developed in this study in describing the impact damage behaviors of composite materials. In addition, the characteristics and degree of damage in composite laminates are analyzed and discussed based on this PD model. The difference in the impact resistance of composite laminates with different stacking sequences is also studied using the numerical simulation results. Full article
(This article belongs to the Special Issue Computational Fracture and Damage Modeling of Engineered Materials)
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17 pages, 10932 KB  
Article
Photoluminescence and Photocatalytic Properties of MWNTs Decorated with Fe-Doped ZnO Nanoparticles
by Adriana Popa, Maria Stefan, Sergiu Macavei, Laura Elena Muresan, Cristian Leostean, Cornelia Veronica Floare-Avram and Dana Toloman
Materials 2023, 16(7), 2858; https://doi.org/10.3390/ma16072858 - 3 Apr 2023
Cited by 6 | Viewed by 2834
Abstract
The present work reports the photoluminescence (PL) and photocatalytic properties of multi-walled carbon nanotubes (MWCNTs) decorated with Fe-doped ZnO nanoparticles. MWCNT:ZnO-Fe nanocomposite samples with weight ratios of 1:3, 1:5 and 1:10 were prepared using a facile synthesis method. The obtained crystalline phases were [...] Read more.
The present work reports the photoluminescence (PL) and photocatalytic properties of multi-walled carbon nanotubes (MWCNTs) decorated with Fe-doped ZnO nanoparticles. MWCNT:ZnO-Fe nanocomposite samples with weight ratios of 1:3, 1:5 and 1:10 were prepared using a facile synthesis method. The obtained crystalline phases were evidenced by X-ray diffraction (XRD). X-ray Photoelectron spectroscopy (XPS) revealed the presence of both 2+ and 3+ valence states of Fe ions in a ratio of approximately 0.5. The electron paramagnetic resonance EPR spectroscopy sustained the presence of Fe3+ ions in the ZnO lattice and evidenced oxygen vacancies. Transmission electron microscopy (TEM) images showed the attachment and distribution of Fe-doped ZnO nanoparticles along the nanotubes with a star-like shape. All of the samples exhibited absorption in the UV region, and the absorption edge was shifted toward a higher wavelength after the addition of MWCNT component. The photoluminescence emission spectra showed peaks in the UV and visible region. Visible emissions are a result of the presence of defects or impurity states in the material. All of the samples showed photocatalytic activity against the Rhodamine B (RhB) synthetic solution under UV irradiation. The best performance was obtained using the MWCNT:ZnO-Fe(1:5) nanocomposite samples, which exhibited a 96% degradation efficiency. The mechanism of photocatalytic activity was explained based on the reactive oxygen species generated by the nanocomposites under UV irradiation in correlation with the structural and optical information obtained in this study. Full article
(This article belongs to the Special Issue Advanced Luminescent Materials and Devices)
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25 pages, 4830 KB  
Review
Semiconductor Characterization by Terahertz Excitation Spectroscopy
by Arūnas Krotkus, Ignas Nevinskas and Ričardas Norkus
Materials 2023, 16(7), 2859; https://doi.org/10.3390/ma16072859 - 3 Apr 2023
Cited by 7 | Viewed by 3707
Abstract
Surfaces of semiconducting materials excited by femtosecond laser pulses emit electromagnetic waves in the terahertz (THz) frequency range, which by definition is the 0.1–10 THz region. The nature of terahertz radiation pulses is, in the majority of cases, explained by the appearance of [...] Read more.
Surfaces of semiconducting materials excited by femtosecond laser pulses emit electromagnetic waves in the terahertz (THz) frequency range, which by definition is the 0.1–10 THz region. The nature of terahertz radiation pulses is, in the majority of cases, explained by the appearance of ultrafast photocurrents. THz pulse duration is comparable with the photocarrier momentum relaxation time, thus such hot-carrier effects as the velocity overshoot, ballistic carrier motion, and optical carrier alignment must be taken into consideration when explaining experimental observations of terahertz emission. Novel commercially available tools such as optical parametric amplifiers that are capable of generating femtosecond optical pulses within a wide spectral range allow performing new unique experiments. By exciting semiconductor surfaces with various photon energies, it is possible to look into the ultrafast processes taking place at different electron energy levels of the investigated materials. The experimental technique known as the THz excitation spectroscopy (TES) can be used as a contactless method to study the band structure and investigate the ultrafast processes of various technologically important materials. A recent decade of investigations with the THz excitation spectroscopy method is reviewed in this article. TES experiments performed on the common bulk A3B5 compounds such as the wide-gap GaAs, and narrow-gap InAs and InSb, as well as Ge, Te, GaSe and other bulk semiconductors are reviewed. Finally, the results obtained by this non-contact technique on low-dimensional materials such as ultrathin mono-elemental Bi films, InAs, InGaAs, and GaAs nanowires are also presented. Full article
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16 pages, 4309 KB  
Article
Solar-Driven Thermocatalytic Synthesis of Octahydroquinazolinone Using Novel Polyvinylchloride (PVC)-Supported Aluminum Oxide (Al2O3) Catalysts
by Abdulrahman I. Alharthi, Mshari A. Alotaibi, Amani M. Alansi, Talal F. Qahtan, Imtiaz Ali, Matar N. Al-Shalwi and Md. Afroz Bakht
Materials 2023, 16(7), 2835; https://doi.org/10.3390/ma16072835 - 2 Apr 2023
Cited by 2 | Viewed by 1921
Abstract
The chemical industry is one of the main fossil fuel consumers, so its reliance on sustainable and renewable resources such as wind and solar energy should be increased to protect the environment. Accordingly, solar-driven thermocatalytic synthesis of octahydroquinazolinone using polyvinylchloride (PVC)-supported aluminum oxide [...] Read more.
The chemical industry is one of the main fossil fuel consumers, so its reliance on sustainable and renewable resources such as wind and solar energy should be increased to protect the environment. Accordingly, solar-driven thermocatalytic synthesis of octahydroquinazolinone using polyvinylchloride (PVC)-supported aluminum oxide (Al2O3) as a catalyst under natural sunlight is proposed in this work. The Al2O3/PVC catalysts were characterized by FT-IR, SEM, BET, XRD, and XPS techniques. The obtained results indicate that the yield and reaction time can be modified by adjusting the molar ratio of the catalyst. To investigate the stability of the catalyst, the spent catalyst was reused in several reactions. The results indicated that, when a 50% Al2O3 catalyst is employed in an absolute solar heat, it performs exceptionally well in terms of yield (98%) and reaction time (35 min). Furthermore, the reaction times and yield of octahydroquinazolinone derivatives with an aryl moiety were superior to those of heteroaryl. All the synthesized compounds were well characterized by FT-IR, 1H-NMR, and 13C-NMR. The current work introduces a new strategy to use solar heat for energy-efficient chemical reactions using a cost-effective, recyclable environmentally friendly PVC/Al2O3 catalyst that produces a high yield. Full article
(This article belongs to the Special Issue Asymmetric/Heterogeneous Catalysis and Green Organic Synthesis)
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18 pages, 6651 KB  
Article
Surface Cement Concrete with Reclaimed Asphalt
by Małgorzata Linek, Magdalena Bacharz and Patrycja Piotrowska
Materials 2023, 16(7), 2791; https://doi.org/10.3390/ma16072791 - 31 Mar 2023
Cited by 3 | Viewed by 1864
Abstract
This research concerns the possibility of using reclaimed asphalt pavement as a substitute for conventional aggregate in cement concrete mixtures for roads and airfield applications. The advantages of using reclaimed asphalt pavement as a replacement for natural aggregates are presented. Economic and environmental [...] Read more.
This research concerns the possibility of using reclaimed asphalt pavement as a substitute for conventional aggregate in cement concrete mixtures for roads and airfield applications. The advantages of using reclaimed asphalt pavement as a replacement for natural aggregates are presented. Economic and environmental aspects are indicated, including the reduction in the consumption of natural non-renewable sources of mineral aggregates, as well as reduction in transport costs and emissions of harmful greenhouse gases. The consistency of this recycled material with the idea of sustainable development in the construction industry is emphasized. The test results of the used reclaimed asphalt and the assessment of the effect of its amount on the change in mechanical, physical and strength parameters of cement concrete are presented. It has been shown that the addition of reclaimed concrete reduces selected parameters of cement concrete, but it is possible to use it in structures with less traffic load, taking into account the sustainable development policy. Full article
(This article belongs to the Special Issue Advanced Materials – Microstructure, Manufacturing and Analysis)
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22 pages, 5544 KB  
Review
Recent Advances of Indium Oxide-Based Catalysts for CO2 Hydrogenation to Methanol: Experimental and Theoretical
by Dongren Cai, Yanmei Cai, Kok Bing Tan and Guowu Zhan
Materials 2023, 16(7), 2803; https://doi.org/10.3390/ma16072803 - 31 Mar 2023
Cited by 29 | Viewed by 6960
Abstract
Methanol synthesis from the hydrogenation of carbon dioxide (CO2) with green H2 has been proven as a promising method for CO2 utilization. Among the various catalysts, indium oxide (In2O3)-based catalysts received tremendous research interest due [...] Read more.
Methanol synthesis from the hydrogenation of carbon dioxide (CO2) with green H2 has been proven as a promising method for CO2 utilization. Among the various catalysts, indium oxide (In2O3)-based catalysts received tremendous research interest due to the excellent methanol selectivity with appreciable CO2 conversion. Herein, the recent experimental and theoretical studies on In2O3-based catalysts for thermochemical CO2 hydrogenation to methanol were systematically reviewed. It can be found that a variety of steps, such as the synthesis method and pretreatment conditions, were taken to promote the formation of oxygen vacancies on the In2O3 surface, which can inhibit side reactions to ensure the highly selective conversion of CO2 into methanol. The catalytic mechanism involving the formate pathway or carboxyl pathway over In2O3 was comprehensively explored by kinetic studies, in situ and ex situ characterizations, and density functional theory calculations, mostly demonstrating that the formate pathway was extremely significant for methanol production. Additionally, based on the cognition of the In2O3 active site and the reaction path of CO2 hydrogenation over In2O3, strategies were adopted to improve the catalytic performance, including (i) metal doping to enhance the adsorption and dissociation of hydrogen, improve the ability of hydrogen spillover, and form a special metal-In2O3 interface, and (ii) hybrid with other metal oxides to improve the dispersion of In2O3, enhance CO2 adsorption capacity, and stabilize the key intermediates. Lastly, some suggestions in future research were proposed to enhance the catalytic activity of In2O3-based catalysts for methanol production. The present review is helpful for researchers to have an explicit version of the research status of In2O3-based catalysts for CO2 hydrogenation to methanol and the design direction of next-generation catalysts. Full article
(This article belongs to the Special Issue Nanocatalysts for CO2 Utilization)
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19 pages, 5451 KB  
Article
Heat Transfer Analysis of Warm Guss Asphalt Concrete for Mini-Trench Overlaying
by Kyung-Nam Kim, Yeong-Min Kim, Sang-Yum Lee and Tri Ho Minh Le
Materials 2023, 16(7), 2808; https://doi.org/10.3390/ma16072808 - 31 Mar 2023
Viewed by 2072
Abstract
Conventional hot mix asphalt overlaying on trench infrastructure typically necessitates extended cooling times for further works and can have adverse effects on buried components, such as electricity cables and hot water pipes. Therefore, this research aims to investigate the use of warm guss [...] Read more.
Conventional hot mix asphalt overlaying on trench infrastructure typically necessitates extended cooling times for further works and can have adverse effects on buried components, such as electricity cables and hot water pipes. Therefore, this research aims to investigate the use of warm guss mastic asphalt (at an installation temperature of 160 °C) as an overlaying material for mini-trenches, which can reduce the cooling time required for traffic opening and improve the efficiency of the construction process. This research involved two stages: first, lab testing and related research results were used to generate the thermal conductivity and specific heat necessary for simulation work. Second, a finite element model analysis was conducted to evaluate the thermal transmission of the overlaying surface and the buried conduit based on the summer pavement temperature distribution through the Korean Pavement Research Program. Afterward, the field test bed was constructed to verify the simulation. The results indicate that the optimal thickness of the overlaying material and the concrete covering should be designed to ensure thermal durability and meet traffic opening requirements. The overlaying depth of the mini trench using warm mix guss mastic asphalt should be less than 100 mm to meet with the traffic opening time, while the thickness of the concrete covering should be designed to be more than 100 mm to ensure thermal durability. Additionally, the findings suggest that the application of warm guss asphalt could reduce the opening time by 30 min to 1 h and 25 min compared to conventional hot guss asphalt materials. When the pavement surface temperature for the traffic opening is controlled at 50 °C, the asphalt mixture requires at least 2 h to 5 h to meet the cooling criteria for traffic opening, respectively. Overall, this research confirms the potential benefits and optimal use of warm guss mastic asphalt in the construction process of mini-trenches. Full article
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18 pages, 14569 KB  
Article
Effect of Graphene Oxide on the Mechanical Properties and Durability of High-Strength Lightweight Concrete Containing Shale Ceramsite
by Xiaojiang Hong, Jin Chai Lee, Jing Lin Ng, Zeety Md Yusof, Qian He and Qiansha Li
Materials 2023, 16(7), 2756; https://doi.org/10.3390/ma16072756 - 30 Mar 2023
Cited by 19 | Viewed by 3514
Abstract
An effective pathway to achieve the sustainable development of resources and environmental protection is to utilize shale ceramsite (SC), which is processed from shale spoil to produce high-strength lightweight concrete (HSLWC). Furthermore, the urgent demand for better performance of HSLWC has stimulated active [...] Read more.
An effective pathway to achieve the sustainable development of resources and environmental protection is to utilize shale ceramsite (SC), which is processed from shale spoil to produce high-strength lightweight concrete (HSLWC). Furthermore, the urgent demand for better performance of HSLWC has stimulated active research on graphene oxide (GO) in strengthening mechanical properties and durability. This study was an effort to investigate the effect of different contents of GO on HSLWC manufactured from SC. For this purpose, six mixtures containing GO in the range of 0–0.08% (by weight of cement) were systematically designed to test the mechanical properties (compressive strength, flexural strength, and splitting tensile strength), durability (chloride penetration resistance, freezing–thawing resistance, and sulfate attack resistance), and microstructure. The experimental results showed that the optimum amount of 0.05% GO can maximize the compressive strength, flexural strength, and splitting tensile strength by 20.1%, 34.3%, and 24.2%, respectively, and exhibited excellent chloride penetration resistance, freezing–thawing resistance, and sulfate attack resistance. Note that when the addition of GO was relatively high, the performance improvement in HSLWC as attenuated instead. Therefore, based on the comprehensive analysis of microstructure, the optimal addition level of GO to achieve the best mechanical properties and durability of HSLWC is considered to be 0.05%. These findings can provide a new method for the use of SC in engineering. Full article
(This article belongs to the Special Issue Advanced Graphene and Graphene Oxide Materials)
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14 pages, 6521 KB  
Article
The Impact of Excitation Periods on the Outcome of Lock-In Thermography
by Milan Sapieta, Vladimír Dekýš, Peter Kopas, Lenka Jakubovičová and Zdenko Šavrnoch
Materials 2023, 16(7), 2763; https://doi.org/10.3390/ma16072763 - 30 Mar 2023
Cited by 4 | Viewed by 1955
Abstract
Thermal imaging is a non-destructive test method that uses an external energy source, such as a halogen lamp or flash lamp, to excite the material under test and measure the resulting temperature distribution. One of the important parameters of lock-in thermography is the [...] Read more.
Thermal imaging is a non-destructive test method that uses an external energy source, such as a halogen lamp or flash lamp, to excite the material under test and measure the resulting temperature distribution. One of the important parameters of lock-in thermography is the number of excitation periods, which is used to calculate a phase image that shows defects or inhomogeneities in the material. The results for multiple periods can be averaged, which leads to noise suppression, but the use of a larger number of periods may cause an increase in noise due to unsynchronization of the camera and the external excitation source or may lead to heating and subsequent damage to the sample. The phase image is the most common way of representing the results of lock-in thermography, but amplitude images and complex images can also be obtained. In this study, eight measurements were performed on different samples using a thermal pulse source (flash lamp and halogen lamp) with a period of 120 s. For each sample, five phase images were calculated using different number of periods, preferably one to five periods. The phase image calculated from one period was used as a reference. To determine the effect of the number of excitation periods on the phase image, the reference phase image for one period was compared with the phase images calculated using multiple periods using the structural similarity index (SSIM) and multi-scale SSIM (MS-SSIM). Full article
(This article belongs to the Special Issue Newer Paradigms in Advanced Materials Characterisation)
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10 pages, 5490 KB  
Article
The Heteroepitaxy of Thick β-Ga2O3 Film on Sapphire Substrate with a β-(AlxGa1−x)2O3 Intermediate Buffer Layer
by Wenhui Zhang, Hezhi Zhang, Song Zhang, Zishi Wang, Litao Liu, Qi Zhang, Xibing Hu and Hongwei Liang
Materials 2023, 16(7), 2775; https://doi.org/10.3390/ma16072775 - 30 Mar 2023
Cited by 4 | Viewed by 2702
Abstract
A high aluminum (Al) content β-(AlxGa1−x)2O3 film was synthesized on c-plane sapphire substrate using the gallium (Ga) diffusion method. The obtained β-(AlxGa1−x)2O3 film had an average thickness [...] Read more.
A high aluminum (Al) content β-(AlxGa1−x)2O3 film was synthesized on c-plane sapphire substrate using the gallium (Ga) diffusion method. The obtained β-(AlxGa1−x)2O3 film had an average thickness of 750 nm and a surface roughness of 2.10 nm. Secondary ion mass spectrometry results indicated the homogenous distribution of Al components in the film. The Al compositions in the β-(AlxGa1−x)2O3 film, as estimated by X-ray diffraction, were close to those estimated by X-ray photoelectron spectroscopy, at ~62% and ~61.5%, respectively. The bandgap of the β-(AlxGa1−x)2O3 film, extracted from the O 1s core-level spectra, was approximately 6.0 ± 0.1 eV. After synthesizing the β-(AlxGa1−x)2O3 film, a thick β-Ga2O3 film was further deposited on sapphire substrate using carbothermal reduction and halide vapor phase epitaxy. The β-Ga2O3 thick film, grown on a sapphire substrate with a β-(AlxGa1−x)2O3 buffer layer, exhibited improved crystal orientation along the (-201) plane. Moreover, the scanning electron microscopy revealed that the surface quality of the β-Ga2O3 thick film on sapphire substrate with a β-(AlxGa1−x)2O3 intermediate buffer layer was significantly improved, with an obvious transition from grain island-like morphology to 2D continuous growth, and a reduction in surface roughness to less than 10 nm. Full article
(This article belongs to the Special Issue Wide and Ultra-Wide Bandgap Semiconductor Materials for Power Devices)
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11 pages, 4074 KB  
Article
Optimization of the Winding Layer Structure of High-Pressure Composite Overwrapped Pressure Vessels
by Chengrui Di, Bo Zhu, Xiangji Guo, Junwei Yu, Yanbin Zhao and Kun Qiao
Materials 2023, 16(7), 2713; https://doi.org/10.3390/ma16072713 - 29 Mar 2023
Cited by 14 | Viewed by 3279
Abstract
The large thickness COPV is designed by netting theory and the finite element simulation method, but the actual performance is low and the cylinder performance still cannot be improved after increasing the thickness of the composite winding layer. This paper analyzes the reasons [...] Read more.
The large thickness COPV is designed by netting theory and the finite element simulation method, but the actual performance is low and the cylinder performance still cannot be improved after increasing the thickness of the composite winding layer. This paper analyzes the reasons for this and puts forward a feasible solution: without changing the thickness of the winding layer, the performance of COPV can be effectively increased by increasing the proportion of annular winding fiber. This method has been verified by tests and is supported by theory. Full article
(This article belongs to the Special Issue Additive Manufacturing of Composites, Volume II)
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14 pages, 6866 KB  
Article
Multifunctional TiO2 Nanotube-Matrix Composites with Enhanced Photocatalysis and Lithium-Ion Storage Performances
by Mengmeng Zhang, Hui Li and Chunrui Wang
Materials 2023, 16(7), 2716; https://doi.org/10.3390/ma16072716 - 29 Mar 2023
Viewed by 1821
Abstract
As a multifunctional material, TiO2 shows excellent performance in catalytic degradation and lithium-ion storage. However, high electron-hole pair recombination, poor conductivity, and low theoretical capacity severely limit the practical application of TiO2. Herein, TiO2 nanotube (TiO2 NT) with [...] Read more.
As a multifunctional material, TiO2 shows excellent performance in catalytic degradation and lithium-ion storage. However, high electron-hole pair recombination, poor conductivity, and low theoretical capacity severely limit the practical application of TiO2. Herein, TiO2 nanotube (TiO2 NT) with a novel double-layer honeycomb structure were prepared by two-step electrochemical anodization. Honeycombed TiO2 NT arrays possess clean top surfaces and a long-range ordering, which greatly facilitates the preparation of high-performance binary and ternary materials. A binary TiO2 nanotube@Au nanoparticle (TiO2 NT@Au NP) composite accompanied by appropriately concentrated and uniformly distributed gold particles was prepared in this work. Interestingly, the TiO2 nanotube@Au nanoparticle (TiO2 NT@Au NP) composites not only showed the excellent catalytic degradation effect of methylene blue, but also demonstrated large lithium-ion storage capacity (310.6 μAh cm−2, 1.6 times of pristine TiO2 NT). Based on the realization of the controllable fabrication of binary TiO2 nanotube@MoS2 nanosheet (TiO2 NT@MoS2 NS) composite, ternary TiO2 nanotube@MoS2 nanosheet@Au nanoparticle (TiO2 NT@MoS2 NS@Au NP) composite with abundant defects and highly ordered structure was also innovatively designed and fabricated. As expected, the TiO2 NT@MoS2 NS@Au NP anode exhibits extremely high initial discharge specific capacity (487.4 μAh cm−2, 2.6 times of pristine TiO2 NT) and excellent capacity retention (81.0%). Full article
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13 pages, 4976 KB  
Article
Vibration and Bandgap Behavior of Sandwich Pyramid Lattice Core Plate with Resonant Rings
by Chengfei Li, Zhaobo Chen and Yinghou Jiao
Materials 2023, 16(7), 2730; https://doi.org/10.3390/ma16072730 - 29 Mar 2023
Cited by 16 | Viewed by 2760
Abstract
The vibration suppression performance of the pyramid lattice core sandwich plates is receiving increasing attention and needs further investigation for technical upgrading of potential engineering applications. Inspired by the localized resonant mechanism of the acoustic metamaterials and considering the integrity of the lattice [...] Read more.
The vibration suppression performance of the pyramid lattice core sandwich plates is receiving increasing attention and needs further investigation for technical upgrading of potential engineering applications. Inspired by the localized resonant mechanism of the acoustic metamaterials and considering the integrity of the lattice sandwich plate, we reshaped a sandwich pyramid lattice core with resonant rings (SPLCRR). Finite element (FE) models are built up for the calculations of the dispersion curves and vibration transmission. The validity of the bandgap of the SPLCRR and remarkable vibration suppression are verified by experimental observations and the numerical methods. Furthermore, the effects of geometric parameters, material parameters and period parameters on the bandgaps of the SPLCRR are systematically investigated, which offers a deeper understanding of the underlying mechanism of bandgap and helps the SPLCRR structure meet the technological update requirements of practical engineering design. Full article
(This article belongs to the Section Mechanics of Materials)
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22 pages, 8107 KB  
Review
Sol–Gel Photonic Glasses: From Material to Application
by Giancarlo C. Righini, Cristina Armellini, Maurizio Ferrari, Alice Carlotto, Alessandro Carpentiero, Andrea Chiappini, Alessandro Chiasera, Anna Lukowiak, Thi Ngoc Lam Tran and Stefano Varas
Materials 2023, 16(7), 2724; https://doi.org/10.3390/ma16072724 - 29 Mar 2023
Cited by 9 | Viewed by 3785
Abstract
In this review, we present a short overview of the development of sol–gel glasses for application in the field of photonics, with a focus on some of the most interesting results obtained by our group and collaborators in that area. Our main attention [...] Read more.
In this review, we present a short overview of the development of sol–gel glasses for application in the field of photonics, with a focus on some of the most interesting results obtained by our group and collaborators in that area. Our main attention is devoted to silicate glasses of different compositions, which are characterized by specific optical and spectroscopic properties for various applications, ranging from luminescent systems to light-confining structures and memristors. In particular, the roles of rare-earth doping, matrix composition, the densification process and the fabrication protocol on the structural, optical and spectroscopic properties of the developed photonic systems are discussed through appropriate examples. Some achievements in the fabrication of oxide sol–gel optical waveguides and of micro- and nanostructures for the confinement of light are also briefly discussed. Full article
(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)
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17 pages, 11294 KB  
Article
Study on Perforation Behavior of PTFE/Al Reactive Material Composite Jet Impacting Steel Target
by Hongda Li, Hui Duan, Zhili Zhang and Yuanfeng Zheng
Materials 2023, 16(7), 2715; https://doi.org/10.3390/ma16072715 - 29 Mar 2023
Cited by 6 | Viewed by 3238
Abstract
To study the penetration and cratering effect of reactive material composite jets, a series of experiments are carried out for the shaped charge (SC) with different composite liners damaging steel targets. The inner layer of composite liners is metal and the outer one [...] Read more.
To study the penetration and cratering effect of reactive material composite jets, a series of experiments are carried out for the shaped charge (SC) with different composite liners damaging steel targets. The inner layer of composite liners is metal and the outer one is a polytetrafluoroethylene/aluminum (PTFE/Al) reactive material. Copper (Cu), titanium (Ti) and Al inner liners are used in this paper. The reactive material liner is composed of 73.5 wt.% PTFE and 26.5 wt.% Al powder through mass-matched ratios. Reactive material composite liners are prepared through machining, cold pressing and a sintering process. The SC mainly consists of a case, a composite liner, high-energy explosive and an initiator. The steel target is steel 45#, with a thickness of 66 mm. A standoff of 1.0 CD (charge diameter) is selected to conduct the penetration experiments. The experimental results show that when the inner layer of the composite liner is composed of Ti and Al, the hole diameters on the steel target formed by the reactive material composite jet are significantly larger than that of the inner Cu liner. By introducing the initiation delay time (τ) and detonation-like reaction model of PTFE/Al reactive materials, an integrated numerical simulation algorithm of the penetration and detonation-like effects of reactive material composite jets is realized. Numerical simulations demonstrate that the initial penetration holes on the steel targets are enlarged under the detonation-like effects of PTFE/Al reactive materials, and the simulated perforation sizes are in good agreement with the experimental results. Full article
(This article belongs to the Special Issue Dynamic Mechanical Analysis of Energetic Materials)
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21 pages, 8593 KB  
Article
Durability and Thermal Behavior of Functional Paints Formulated with Recycled-Glass Hollow Microspheres of Different Size
by Massimo Calovi and Stefano Rossi
Materials 2023, 16(7), 2678; https://doi.org/10.3390/ma16072678 - 28 Mar 2023
Cited by 6 | Viewed by 3005
Abstract
This study aims to assess the effect of hollow glass microspheres of different sizes derived from glass industry waste on the durability and thermal behavior of waterborne paint. The coatings were characterized by electron microscopy to investigate the distribution of the spheres and [...] Read more.
This study aims to assess the effect of hollow glass microspheres of different sizes derived from glass industry waste on the durability and thermal behavior of waterborne paint. The coatings were characterized by electron microscopy to investigate the distribution of the spheres and their influence on the layer morphology. The impact of the various glassy spheres on the mechanical feature of the coatings was assessed using the Buchholz hardness test and the Scrub abrasion test. The role of the spheres in altering the durability of the samples was analyzed by the salt spray exposure test and the electrochemical impedance spectroscopy measurements. Finally, a specific accelerated degradation test was carried out to explore the evolution of the thermal behavior of the composite coatings. Ultimately, this work revealed the pros and cons of using hollow glass spheres as a multifunctional paint filler, highlighting the size of the spheres as a key parameter. For example, spheres with adequate size (25–44 µm), totally embedded in the polymeric matrix, are able to reduce the thermal conductivity of the coating avoiding local heat accumulation phenomena. Full article
(This article belongs to the Special Issue Methodology of the Design and Testing of Composite Structures)
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14 pages, 3085 KB  
Article
Damage Propagation by Cyclic Loading in Drilled Carbon/Epoxy Plates
by Luis M. P. Durão, João E. Matos, Nuno C. Loureiro, José L. Esteves and Susana C. F. Fernandes
Materials 2023, 16(7), 2688; https://doi.org/10.3390/ma16072688 - 28 Mar 2023
Cited by 7 | Viewed by 2024
Abstract
Fiber reinforced composites are widely used in the production of parts for load bearing structures. It is generally recognized that composites can be affected both by monotonic and cyclic loading. For assembly purposes, drilling is needed, but holes can act as stress concentration [...] Read more.
Fiber reinforced composites are widely used in the production of parts for load bearing structures. It is generally recognized that composites can be affected both by monotonic and cyclic loading. For assembly purposes, drilling is needed, but holes can act as stress concentration notches, leading to damage propagation and failure. In this work, a batch of carbon/epoxy plates is drilled by different drill geometries, while thrust force is monitored and the hole’s surrounding region is inspected. Based on radiographic images, the area and other features of the damaged region are computed for damage assessment. Finally, the specimens are subjected to Bearing Fatigue tests. Cyclic loading causes ovality of the holes and the loss of nearly 10% of the bearing net strength. These results can help to establish an association between the damaged region and the material’s fatigue resistance, as larger damage extension and deformation by cyclic stress contribute to the loss of load carrying capacity of parts. Full article
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25 pages, 14854 KB  
Review
The Characteristic Microstructures and Properties of Steel-Based Alloy via Additive Manufacturing
by Chunlei Shang, Honghui Wu, Guangfei Pan, Jiaqi Zhu, Shuize Wang, Guilin Wu, Junheng Gao, Zhiyuan Liu, Ruidi Li and Xinping Mao
Materials 2023, 16(7), 2696; https://doi.org/10.3390/ma16072696 - 28 Mar 2023
Cited by 8 | Viewed by 3633
Abstract
Differing from metal alloys produced by conventional techniques, metallic products prepared by additive manufacturing experience distinct solidification thermal histories and solid−state phase transformation processes, resulting in unique microstructures and superior performance. This review starts with commonly used additive manufacturing techniques in steel−based alloy [...] Read more.
Differing from metal alloys produced by conventional techniques, metallic products prepared by additive manufacturing experience distinct solidification thermal histories and solid−state phase transformation processes, resulting in unique microstructures and superior performance. This review starts with commonly used additive manufacturing techniques in steel−based alloy and then some typical microstructures produced by metal additive manufacturing technologies with different components and processes are summarized, including porosity, dislocation cells, dendrite structures, residual stress, element segregation, etc. The characteristic microstructures may exert a significant influence on the properties of additively manufactured products, and thus it is important to tune the components and additive manufacturing process parameters to achieve the desired microstructures. Finally, the future development and prospects of additive manufacturing technology in steel are discussed. Full article
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21 pages, 3548 KB  
Review
Application of Nano-Crystalline Diamond in Tribology
by Yue Xia, Yunxiang Lu, Guoyong Yang, Chengke Chen, Xiaojun Hu, Hui Song, Lifen Deng, Yuezhong Wang, Jian Yi and Bo Wang
Materials 2023, 16(7), 2710; https://doi.org/10.3390/ma16072710 - 28 Mar 2023
Cited by 13 | Viewed by 3576
Abstract
Nano-crystalline diamond has been extensively researched and applied in the fields of tribology, optics, quantum information and biomedicine. In virtue of its hardness, the highest in natural materials, diamond outperforms the other materials in terms of wear resistance. Compared to traditional single-crystalline and [...] Read more.
Nano-crystalline diamond has been extensively researched and applied in the fields of tribology, optics, quantum information and biomedicine. In virtue of its hardness, the highest in natural materials, diamond outperforms the other materials in terms of wear resistance. Compared to traditional single-crystalline and poly-crystalline diamonds, nano-crystalline diamond consists of disordered grains and thus possesses good toughness and self-sharpening. These merits render nano-crystalline diamonds to have great potential in tribology. Moreover, the re-nucleation of nano-crystalline diamond during preparation is beneficial to decreasing surface roughness due to its ultrafine grain size. Nano-crystalline diamond coatings can have a friction coefficient as low as single-crystal diamonds. This article briefly introduces the approaches to preparing nano-crystalline diamond materials and summarizes their applications in the field of tribology. Firstly, nano-crystalline diamond powders can be used as additives in both oil- and water-based lubricants to significantly enhance their anti-wear property. Nano-crystalline diamond coatings can also act as self-lubricating films when they are deposited on different substrates, exhibiting excellent performance in friction reduction and wear resistance. In addition, the research works related to the tribological applications of nano-crystalline diamond composites have also been reviewed in this paper. Full article
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14 pages, 2102 KB  
Article
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 3 | Viewed by 2597
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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16 pages, 4043 KB  
Article
Effective and Efficient Porous CeO2 Adsorbent for Acid Orange 7 Adsorption
by Yaohui Xu, Liangjuan Gao, Jinyuan Yang, Qingxiu Yang, Wanxin Peng and Zhao Ding
Materials 2023, 16(7), 2650; https://doi.org/10.3390/ma16072650 - 27 Mar 2023
Cited by 4 | Viewed by 1960
Abstract
A porous CeO2 was synthesized following the addition of guanidine carbonate to a Ce3+ aqueous solution, the subsequent addition of hydrogen peroxide and a final hydrothermal treatment. The optimal experimental parameters for the synthesis of porous CeO2, including the [...] Read more.
A porous CeO2 was synthesized following the addition of guanidine carbonate to a Ce3+ aqueous solution, the subsequent addition of hydrogen peroxide and a final hydrothermal treatment. The optimal experimental parameters for the synthesis of porous CeO2, including the amounts of guanidine carbonate and hydrogen peroxide and the hydrothermal conditions, were determined by taking the adsorption efficiency of acid orange 7 (AO7) dye as the evaluation. A template−free hydrothermal strategy could avoid the use of soft or hard templates and the subsequent tedious procedures of eliminating templates, which aligned with the goals of energy conservation and emission reduction. Moreover, both the guanidine carbonate and hydrogen peroxide used in this work were accessible and eco−friendly raw materials. The porous CeO2 possessed rapid adsorption capacities for AO7 dye. When the initial concentration of AO7 was less than 130 mg/L, removal efficiencies greater than 90.0% were obtained, achieving a maximum value of 97.5% at [AO7] = 100 mg/L and [CeO2] = 2.0 g/L in the first 10 min of contact. Moreover, the adsorption–desorption equilibrium between the porous CeO2 adsorbent and the AO7 molecule was basically established within the first 30 min. The saturated adsorption amount of AO7 dye was 90.3 mg/g based on a Langmuir linear fitting of the experimental data. Moreover, the porous CeO2 could be recycled using a NaOH aqueous solution, and the adsorption efficiency of AO7 dye still remained above 92.5% after five cycles. This study provided an alternative porous adsorbent for the purification of dye wastewater, and a template−free hydrothermal strategy was developed to enable the design of CeO2−based catalysts or catalyst carriers. Full article
(This article belongs to the Special Issue Recent Progress in Advanced Adsorption Materials)
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18 pages, 20311 KB  
Article
Study on Dynamic Mechanical Properties of Carbon Fiber-Reinforced Polymer Laminates at Ultra-Low Temperatures
by Wenhao Zhao, Sanchun Lin, Wenfeng Wang, Yifan Yang, Xuan Yan and Heng Yang
Materials 2023, 16(7), 2654; https://doi.org/10.3390/ma16072654 - 27 Mar 2023
Cited by 6 | Viewed by 2389
Abstract
This study uses experimental methods, theoretical research, and numerical prediction to study the dynamic mechanical properties and damage evolution of CFRP laminates at ultra-low temperatures. Based on the Split Hopkinson Pressure Bar (SHPB) device, we set up an ultra-low temperature dynamic experimental platform [...] Read more.
This study uses experimental methods, theoretical research, and numerical prediction to study the dynamic mechanical properties and damage evolution of CFRP laminates at ultra-low temperatures. Based on the Split Hopkinson Pressure Bar (SHPB) device, we set up an ultra-low temperature dynamic experimental platform with a synchronous observation function; the dynamic mechanical properties of laminates were tested, and the damage evolution process was observed. The experimental results are as follows: The compression strength and modulus increase linearly with the increase in strain rate and show a quadratic function trend of increasing and then decreasing with the decrease in temperature. The damage degree of the dynamic bending sample increases obviously with the impact velocity and decreases first and then increases with the decrease in temperature. Based on the low-temperature dynamic damage constitutive, failure criterion, and interlayer interface damage constitutive of the laminates, a numerical model was established to predict the dynamic mechanical properties and damage evolution process of CFRP laminates at ultra-low temperatures, and the finite element analysis (FEA) results are consistent with the experimental results. The results of this paper strongly support the application and safety evaluation of CFRP composites in extreme environments, such as deep space exploration. Full article
(This article belongs to the Special Issue Carbon Fiber Reinforced Polymers (2nd Edition))
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38 pages, 29807 KB  
Review
Theory, Method and Practice of Metal Deformation Instability: A Review
by Miaomiao Wan, Fuguo Li, Kenan Yao, Guizeng Song and Xiaoguang Fan
Materials 2023, 16(7), 2667; https://doi.org/10.3390/ma16072667 - 27 Mar 2023
Cited by 12 | Viewed by 5683
Abstract
Deformation instability is a macroscopic and microscopic phenomenon of non-uniformity and unstable deformation of materials under stress loading conditions, and it is affected by the intrinsic characteristics of materials, the structural geometry of materials, stress state and environmental conditions. Whether deformation instability is [...] Read more.
Deformation instability is a macroscopic and microscopic phenomenon of non-uniformity and unstable deformation of materials under stress loading conditions, and it is affected by the intrinsic characteristics of materials, the structural geometry of materials, stress state and environmental conditions. Whether deformation instability is positive and constructive or negative and destructive, it objectively affects daily life at all times and the deformation instability based on metal-bearing analysis in engineering design has always been the focus of attention. Currently, the literature on deformation instability in review papers mainly focuses on the theoretical analysis of deformation instability (instability criteria). However, there are a limited number of papers that comprehensively classify and review the subject from the perspectives of material characteristic response, geometric structure response, analysis method and engineering application. Therefore, this paper aims to provide a comprehensive review of the existing literature on metal deformation instability, covering its fundamental principles, analytical methods, and engineering practices. The phenomenon and definition of deformation instability, the principle and viewpoint of deformation instability, the theoretical analysis, experimental research and simulation calculation of deformation instability, and the engineering application and prospect of deformation instability are described. This will provide a reference for metal bearing analysis and deformation instability design according to material deformation instability, structural deformation instability and localization conditions of deformation instability, etc. From the perspective of practical engineering applications, regarding the key problems in researching deformation instability, using reverse thinking to deduce and analyze the characteristics of deformation instability is the main trend of future research. Full article
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22 pages, 3804 KB  
Review
Progress and Perspective of Glass-Ceramic Solid-State Electrolytes for Lithium Batteries
by Liyang Lin, Wei Guo, Mengjun Li, Juan Qing, Chuang Cai, Ping Yi, Qibo Deng and Wei Chen
Materials 2023, 16(7), 2655; https://doi.org/10.3390/ma16072655 - 27 Mar 2023
Cited by 14 | Viewed by 5653
Abstract
The all-solid-state lithium battery (ASSLIB) is one of the key points of future lithium battery technology development. Because solid-state electrolytes (SSEs) have higher safety performance than liquid electrolytes, and they can promote the application of Li-metal anodes to endow batteries with higher energy [...] Read more.
The all-solid-state lithium battery (ASSLIB) is one of the key points of future lithium battery technology development. Because solid-state electrolytes (SSEs) have higher safety performance than liquid electrolytes, and they can promote the application of Li-metal anodes to endow batteries with higher energy density. Glass-ceramic SSEs with excellent ionic conductivity and mechanical strength are one of the main focuses of SSE research. In this review paper, we discuss recent advances in the synthesis and characterization of glass-ceramic SSEs. Additionally, some discussions on the interface problems commonly found in glass-ceramic SSEs and their solutions are provided. At the end of this review, some drawbacks of glass-ceramic SSEs are summarized, and future development directions are prospected. We hope that this review paper can help the development of glass-ceramic solid-state electrolytes. Full article
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17 pages, 9819 KB  
Article
Impact of Titanium Addition on Microstructure, Corrosion Resistance, and Hardness of As-Cast Al+6%Li Alloy
by Marcin Adamiak, Augustine Nana Sekyi Appiah, Anna Woźniak, Paweł M. Nuckowski, Shuhratjon Abdugulomovich Nazarov and Izatullo Navruzovich Ganiev
Materials 2023, 16(7), 2671; https://doi.org/10.3390/ma16072671 - 27 Mar 2023
Cited by 4 | Viewed by 3047
Abstract
Aluminum–lithium alloys have the potential for use in aerospace applications, and improving their physical, mechanical, and operational characteristics through alloying is a pressing task. Lithium, with a density of 0.54 g/cm3, enhances the elastic modulus of aluminum while reducing the weight [...] Read more.
Aluminum–lithium alloys have the potential for use in aerospace applications, and improving their physical, mechanical, and operational characteristics through alloying is a pressing task. Lithium, with a density of 0.54 g/cm3, enhances the elastic modulus of aluminum while reducing the weight of the resulting alloys, making them increasingly attractive. Adding transition metal additives to aluminum alloys enhances their strength, heat resistance, and corrosion resistance, due to their modifying effect and grain refinement. The study aimed to investigate the impact of titanium content on the microstructure, corrosion resistance, and hardness of Al-Li alloys. Four alloys were prepared with varying amounts of titanium at 0.05 wt%, 0.1 wt%, 0.5 wt%, and 1.0 wt%. The results showed that the microstructure of the alloy was modified after adding Ti, resulting in a decrease in average grain size to about 60% with the best refinement at 0.05 wt% Ti content. SEM and EDS analysis revealed an irregular net-shaped interdendritic microstructure with an observed microsegregation of Al3Li compounds and other trace elements at the grain boundaries. The samples showed casting defects due to the high content of Li in the alloy, which absorbed air during casting, resulting in casting defects such as shrinkage holes. The corrosion resistance test results were low for the samples with casting defects, with the least resistance recorded for a sample containing 0.1 wt% Ti content, with more casting defects. The addition of Ti increased the microhardness of the alloy to an average of 91.8 ± 2.8 HV. Full article
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17 pages, 33833 KB  
Article
Influence of Accidental Impurities on the Spectroscopic and Luminescent Properties of ZnWO4 Crystal
by Kirill Subbotin, Anatolii Titov, Victoria Solomatina, Andrew Khomyakov, Ekaterina Pakina, Viktor Yakovlev, Damir Valiev, Marina Zykova, Kristina Kuleshova, Yana Didenko, Denis Lis, Mikhail Grishechkin, Sergei Batygov, Sergei Kuznetsov and Igor Avetissov
Materials 2023, 16(7), 2611; https://doi.org/10.3390/ma16072611 - 25 Mar 2023
Cited by 1 | Viewed by 1886
Abstract
Special techniques for deep purification of ZnO and WO3 have been developed in this work. A ZnWO4 single crystal has been grown by the Czochralski method using purified ZnO and WO3 chemicals, along with the ZnWO4 crystal-etalon, which has [...] Read more.
Special techniques for deep purification of ZnO and WO3 have been developed in this work. A ZnWO4 single crystal has been grown by the Czochralski method using purified ZnO and WO3 chemicals, along with the ZnWO4 crystal-etalon, which has been grown at the same conditions using commercially available 5N ZnO and WO3 chemicals. The actual accidental impurities compositions of both the initial chemicals and the grown crystals have been measured by inductively coupled plasma mass-spectrometry. A complex of comparative spectroscopic studies of the crystals has been performed, including optical absorption spectra, photo-, X-ray-, and cathodoluminescence spectra and decay kinetics, as well as the photoluminescence excitation spectra. The revealed differences in the measured properties of the crystals have been analyzed in terms of influence of the accidental impurities on these properties. Full article
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12 pages, 3962 KB  
Article
Laser Emission Spectroscopy of Graphene Oxide Deposited on 316 Steel and Ti6Al4V Titanium Alloy Suitable for Orthopedics
by Barbara Nasiłowska, Wojciech Skrzeczanowski, Aneta Bombalska and Zdzisław Bogdanowicz
Materials 2023, 16(7), 2574; https://doi.org/10.3390/ma16072574 - 24 Mar 2023
Cited by 8 | Viewed by 1938
Abstract
This paper presents the results of an analysis of carbon (in the form of graphene oxide) deposited on the surface of threads made from stainless steel 316 and titanium alloy Ti6Al4V used in orthopedics using Laser Induced Breakdown Spectroscopy (LIBS). The aim of [...] Read more.
This paper presents the results of an analysis of carbon (in the form of graphene oxide) deposited on the surface of threads made from stainless steel 316 and titanium alloy Ti6Al4V used in orthopedics using Laser Induced Breakdown Spectroscopy (LIBS). The aim of the article is to indicate the possibility of using the LIBS spectra for the study of thin layers, including graphene derivatives and other elements. Stratigraphic measurements allowed the detection of differences in the spectra peaks of individual elements, not only in the surface layer itself and in the native material, but also in the intermediate layer connecting the two layers. Due to the clear difference in the outline of the spectrum of graphene oxide and the spectrum of the native material of the samples analyzed, a clear incorporation of carbon atoms into the surface layer was observed. A factor analysis was performed, which confirmed the incorporation of graphene oxide into the surface layer of the native material of the elements examined. Full article
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15 pages, 16472 KB  
Article
Enhanced Mechanical and Corrosion Properties via Annealing Treatment on the Hot-Rolled Ti-Zr-Mo Alloy
by Yun Yue, Mingxing Qi, Tianshuo Song, Bohan Chen, Yihao Tang and Chaoqun Xia
Materials 2023, 16(7), 2597; https://doi.org/10.3390/ma16072597 - 24 Mar 2023
Cited by 3 | Viewed by 1688
Abstract
In this work, the Ti-20Zr-15Mo alloy in its hot-rolled state was annealed in different phase zones, and the effects of the annealing treatment on the phase composition, organization, mechanical and corrosion resistance properties of the alloy were systematically investigated. The results showed that [...] Read more.
In this work, the Ti-20Zr-15Mo alloy in its hot-rolled state was annealed in different phase zones, and the effects of the annealing treatment on the phase composition, organization, mechanical and corrosion resistance properties of the alloy were systematically investigated. The results showed that the original β grains of the alloy had all recrystallized to form the β equiaxial grains when annealed at 800 °C, and the grains had been significantly refined. This allowed the alloy to reach a tensile strength of 1000 MPa, a maximum of 28% after stretching, and a significant increase in plasticity. Also, due to the single beta phase, there was no galvanic corrosion, making the alloy annealed at 800 °C have the best corrosion resistance. Full article
(This article belongs to the Section Mechanics of Materials)
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17 pages, 4390 KB  
Article
Long-Term Oxidation of Zirconium Alloy in Simulated Nuclear Reactor Primary Coolant—Experiments and Modeling
by Iva Betova, Martin Bojinov and Vasil Karastoyanov
Materials 2023, 16(7), 2577; https://doi.org/10.3390/ma16072577 - 24 Mar 2023
Cited by 3 | Viewed by 2880
Abstract
Oxidation of Zr-1%Nb fuel cladding alloy in simulated primary coolant of a pressurized water nuclear reactor is followed by in-situ electrochemical impedance spectroscopy. In-depth composition and thickness of the oxide are estimated by ex-situ analytical techniques. A kinetic model of the oxidation process [...] Read more.
Oxidation of Zr-1%Nb fuel cladding alloy in simulated primary coolant of a pressurized water nuclear reactor is followed by in-situ electrochemical impedance spectroscopy. In-depth composition and thickness of the oxide are estimated by ex-situ analytical techniques. A kinetic model of the oxidation process featuring interfacial reactions of metal oxidation and water reduction, as well as electron and ion transport through the oxide governed by diffusion-migration, is parameterized by quantitative comparison to impedance data. The effects of compressive stress on diffusion and ionic space charge on migration of ionic point defects are introduced to rationalize the dependence of transport parameters on thickness (or oxidation time). The influence of ex-situ and in-situ hydrogen charging on kinetic and transport parameters is also studied. Full article
(This article belongs to the Special Issue Corrosion and Mechanical Behavior of Metal Materials)
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14 pages, 3614 KB  
Article
Black Liquor and Wood Char-Derived Nitrogen-Doped Carbon Materials for Supercapacitors
by Loreta Tamasauskaite-Tamasiunaite, Jolita Jablonskienė, Dijana Šimkūnaitė, Aleksandrs Volperts, Ance Plavniece, Galina Dobele, Aivars Zhurinsh, Vitalija Jasulaitiene, Gediminas Niaura, Audrius Drabavicius, Mari Juel, Luis Colmenares-Rausseo, Ivar Kruusenberg, Kätlin Kaare and Eugenijus Norkus
Materials 2023, 16(7), 2551; https://doi.org/10.3390/ma16072551 - 23 Mar 2023
Cited by 7 | Viewed by 2399
Abstract
Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kraft pulping residue, black liquor, and wood charcoal as carbon sources. The synthesized nitrogen-doped carbon materials, based on black liquor and its mixture with wood charcoal, exhibited high specific surface areas [...] Read more.
Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kraft pulping residue, black liquor, and wood charcoal as carbon sources. The synthesized nitrogen-doped carbon materials, based on black liquor and its mixture with wood charcoal, exhibited high specific surface areas (SSAs) of 2481 and 2690 m2 g−1, respectively, as well as a high volume of mesopores with an average size of 2.9–4.6 nm. The nitrogen content was approximately 3–4 at% in the synthesized nitrogen-doped carbon materials. A specific capacitance of approximately 81–142 F g−1 was achieved in a 1 M Na2SO4 aqueous solution at a current density of 0.2 A g−1. In addition, the specific capacitance retention was 99% after 1000 cycles, indicating good electrochemical stability. Full article
(This article belongs to the Special Issue Nanostructured Materials for Electrochemical Energy Storage)
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