Materials

Open AccessArticle

The Polyol Process and the Synthesis of ζ Intermetallic Compound Ag₅Sn_0.9

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Roland Mahayri

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Mohammed Ali Bousnina

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Materials 2022, 15(22), 8276; https://doi.org/10.3390/ma15228276 - 21 Nov 2022

Viewed by 1394

Abstract

The present work concerns the intermetallic compound (IMC) existing in the Ag–Sn system and its potential use in electronics as attachment materials allowing the adhesion of the chip to the substrate forming the power module. First, we present the synthesis protocol in polyol [...] Read more.

The present work concerns the intermetallic compound (IMC) existing in the Ag–Sn system and its potential use in electronics as attachment materials allowing the adhesion of the chip to the substrate forming the power module. First, we present the synthesis protocol in polyol medium of a compound with the chemical formula Ag₅Sn_0.9 belonging to the solid solution of composition located between 9 and 16 at.% Sn, known as solid solution ζ (or ζ-Ag₄Sn). This phase corresponds to the peritectic invariant point at 724 °C. Differential thermal analysis and X-ray dispersive analysis confirm the single-phased (monocrystalline) nature of the Ag₅Sn_0.9 powder issued after synthesis. Scanning electron microscopy shows that Ag₅Sn_0.9 particles are spherical, and range in submicronic size of around 0.18 μm. X-ray diffraction analysis reveals that the ζ phase mostly exists under the two allotropic varieties (orthorhombic symmetry and hexagonal symmetry) with however a slight excess of the hexagonal variety (60% for the hexagonal variety and 40% for the orthorhombic variety). The lattice parameters resulting from this study for the two allotropic varieties are in good agreement with the Hume-Rothery rules. Full article

(This article belongs to the Special Issue Intermetallic Alloys: Preparation, Properties and Applications)

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Open AccessArticle

Elastoplastic Analysis of Circular Steel Tube of CFT Stub Columns under Axial Compression

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Materials 2022, 15(22), 8275; https://doi.org/10.3390/ma15228275 - 21 Nov 2022

Viewed by 1223

Abstract

Composite action between the components of the concrete-filled steel tube (CFT) is complex and it is difficult to accurately obtain the experimental relationship between the steel tube and the core concrete of CFT columns. The triaxially stressed core concrete has been studied by [...] Read more.

Composite action between the components of the concrete-filled steel tube (CFT) is complex and it is difficult to accurately obtain the experimental relationship between the steel tube and the core concrete of CFT columns. The triaxially stressed core concrete has been studied by hydrostatic test in past research, while little research has been focused on the mechanical behavior of steel tube of CFT columns. It is difficult to obtain the experimental constitutive relationship of the steel tube of CFT columns to reflect the real-time influence of biaxial stress state and local buckling of steel plate on the steel tube. To clarify the mechanical behavior of the steel tube of CFT columns, this paper proposed an elastoplastic analytical method considering biaxial stress state and local buckling of steel tube to obtain the stress–strain curve of the steel tube. This method applied the Hook’s law and the plasticity theory to interpret the information conveyed by the measured vertical and hoop strain histories of the steel tube. To verify its effectiveness, 11 circular concrete-filled steel tube stub columns were fabricated and tested under axial compression. Superposition results of the axial load–strain of steel tube and core concrete were compared against the experimental curves. The widely used Sakino–Sun model of the confined concrete was adopted to calculate the axial load–strain curve of the core concrete. Satisfactory agreements between the calculated and experimental results confirmed the rationality of the proposed method in tracing the constitutive relation of the biaxially stressed steel tube even after the occurrence of the local buckling. The obtained stress–strain relationship is critical for establishment of mathematical constitutive model and finite element model of steel tube. Full article

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Open AccessArticle

Solubilization and Thermodynamic Analysis of Isotretinoin in Eleven Different Green Solvents at Different Temperatures

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Materials 2022, 15(22), 8274; https://doi.org/10.3390/ma15228274 - 21 Nov 2022

Cited by 1 | Viewed by 1120

Abstract

The solubilization and thermodynamic analysis of isotretinoin (ITN) in eleven distinct green solvents, such as water, methyl alcohol (MeOH), ethyl alcohol (EtOH), 1-butyl alcohol (1-BuOH), 2-butyl alcohol (2-BuOH), ethane-1,2-diol (EG), propane-1,2-diol (PG), polyethylene glycol-400 (PEG-400), ethyl acetate (EA), Transcutol-HP (THP), and dimethyl sulfoxide [...] Read more.

The solubilization and thermodynamic analysis of isotretinoin (ITN) in eleven distinct green solvents, such as water, methyl alcohol (MeOH), ethyl alcohol (EtOH), 1-butyl alcohol (1-BuOH), 2-butyl alcohol (2-BuOH), ethane-1,2-diol (EG), propane-1,2-diol (PG), polyethylene glycol-400 (PEG-400), ethyl acetate (EA), Transcutol-HP (THP), and dimethyl sulfoxide (DMSO) was studied at several temperatures and a fixed atmospheric pressure. The equilibrium approach was used to measure the solubility of ITN, and the Apelblat, van’t Hoff, and Buchowski–Ksiazczak λh models were used to correlate the results. The overall uncertainties were less than 5.0% for all the models examined. The highest ITN mole fraction solubility was achieved as 1.01 × 10⁻¹ in DMSO at 318.2 K; however, the least was achieved as 3.16 × 10⁻⁷ in water at 298.2 K. ITN solubility was found to be enhanced with an increase in temperature and the order in which it was soluble in several green solvents at 318.2 K was as follows: DMSO (1.01 × 10⁻¹) > EA (1.73 × 10⁻²) > PEG-400 (1.66 × 10⁻²) > THP (1.59 × 10⁻²) > 2-BuOH (6.32 × 10⁻³) > 1-BuOH (5.88 × 10⁻³) > PG (4.83 × 10⁻³) > EtOH (3.51 × 10⁻³) > EG (3.49 × 10⁻³) > MeOH (2.10 × 10⁻³) > water (1.38 × 10⁻⁶). ITN–DMSO showed the strongest solute–solvent interactions when compared to the other ITN and green solvent combinations. According to thermodynamic studies, ITN dissolution was endothermic and entropy-driven in all of the green solvents tested. The obtained outcomes suggested that DMSO appears to be the best green solvent for ITN solubilization. Full article

(This article belongs to the Special Issue Development and Application of Greener Organic Solvents)

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Open AccessEditor’s ChoiceArticle

Effect of TiO₂ Additives on the Stabilization of h-YbFeO₃ and Promotion of Photo-Fenton Activity of o-YbFeO₃/h-YbFeO₃/r-TiO₂ Nanocomposites

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Materials 2022, 15(22), 8273; https://doi.org/10.3390/ma15228273 - 21 Nov 2022

Cited by 2 | Viewed by 1086

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Nanostructured hexagonal rare-earth orthoferrites (h-RfeO₃, R = Sc, Y, Tb-Lu) are well known as a highly effective base for visible-light-driven heterojunction photocatalysts. However, their application is limited by metastability, leading to difficulties in synthesis due to the irreversible transformation [...] Read more.

Nanostructured hexagonal rare-earth orthoferrites (h-RfeO₃, R = Sc, Y, Tb-Lu) are well known as a highly effective base for visible-light-driven heterojunction photocatalysts. However, their application is limited by metastability, leading to difficulties in synthesis due to the irreversible transformation to a stable orthorhombic structure. In this work, we report on a simple route to the stabilization of h-YbFeO₃ nanocrystals by the synthesis of multiphase nanocomposites with titania additives. The new I-type heterojunction nanocomposites of o-YbFeO₃/h-YbFeO₃/r-TiO₂ were obtained by the glycine–nitrate solution combustion method with subsequent heat treatment of the products. An increase in the mole fraction of the h-YbFeO₃ phase in nanocomposites was found with the titanium addition, indicating its stabilizing effect via limiting mass transfer over heat treatment. The complex physicochemical analysis shows multiple contacts of individual nanocrystals of o-YbFeO₃ (44.4–50.6 nm), h-YbFeO₃ (7.5–17.6 nm), and rutile r-TiO₂ (~5 nm), confirming the presence of the heterojunction structure in the obtained nanocomposite. The photocatalytic activity of h-YbFeO₃/o-YbFeO₃/r-TiO₂ nanocomposites was evaluated by the photo-Fenton degradation of the methyl violet under visible light (λ ≥ 400 nm). It was demonstrated that the addition of 5 mol.% of TiO₂ stabilizes h-YbFeO₃, which allowed us to achieve a 41.5 mol% fraction, followed by a three-time increase in the photodecomposition rate constant up to 0.0160 min⁻¹. Full article

(This article belongs to the Special Issue New Advances in Nanomaterials)

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Open AccessArticle

Mixed-Type Skyrmions in Symmetric Pt/Co/Pt Multilayers at Room Temperature

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Materials 2022, 15(22), 8272; https://doi.org/10.3390/ma15228272 - 21 Nov 2022

Viewed by 1070

Abstract

We demonstrate the generation of mixed-type skyrmions (all are about 200 nm) that are primarily Bloch-type, hybrid-type, and a negligible amount of Néel-type in symmetric Pt/Co(1.55)/Pt multilayers at room temperature. The magnetic field dependence of skyrmion evolution is reversible. Brillouin light-scattering is used [...] Read more.

We demonstrate the generation of mixed-type skyrmions (all are about 200 nm) that are primarily Bloch-type, hybrid-type, and a negligible amount of Néel-type in symmetric Pt/Co(1.55)/Pt multilayers at room temperature. The magnetic field dependence of skyrmion evolution is reversible. Brillouin light-scattering is used to quantitatively quantify the Dzyaloshinskii-Moriya interaction constant D in order to comprehend the mechanism. Interestingly, the D value is high enough to generate skyrmions in a symmetric sandwich structure. Micromagnetic simulations show that Néel-type skyrmions transform into Bloch-type skyrmions as the D value decreases. The interface-induced non-uniform D may be the cause to generate mixed-type skyrmions. This work broadens the flexibility to generate skyrmions by engineering skyrmion-based devices with nominally symmetric multilayers without the requirement of very large DMI. Full article

(This article belongs to the Special Issue Advances in Spintronics of Noncollinear Magnets)

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Open AccessArticle

Microstructure Evolution and Mechanical Properties of Ferrite–Austenite Duplex Fe-Mn-Al-(Cu)-C Steel under Different Annealing Temperatures

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Materials 2022, 15(22), 8271; https://doi.org/10.3390/ma15228271 - 21 Nov 2022

Cited by 2 | Viewed by 1009

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The effect of Cu addition and the intercritical annealing (IA) temperature on the microstructural evolution and mechanical properties of Fe-0.4C-7Mn-4Al (wt%) was investigated via scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD) and nanoindentation tests. The results showed that the [...] Read more.

The effect of Cu addition and the intercritical annealing (IA) temperature on the microstructural evolution and mechanical properties of Fe-0.4C-7Mn-4Al (wt%) was investigated via scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD) and nanoindentation tests. The results showed that the volume fraction and the average grain size of austenite, and the fraction of high angle grain boundaries, increased with IA temperature increase in the range of 650 °C to 710 °C. The addition of Cu facilitates the formation of Cu-rich nanoparticles, raises the volume fraction of austenite, and delays the recrystallization of austenite. As IA temperature increased, the yield strength (YS), ultimate tensile strength (UTS), and Lüders bands strain (LBS) decreased in both experimental steels. The Cu addition not only increases the YS of medium Mn steel but also benefits the decrease of LBS. The best comprehensive mechanical properties were obtained at the IA temperature of 690 °C in the studied steel, with Cu addition. According to nanoindentation experiments, the Cu addition raises the hardness of ferrite and austenite from 4.7 GPa to 6.3 GPa and 7.4 GPa to 8.5 GPa, respectively, contributing to the increase of YS of medium-Mn steel. Full article

(This article belongs to the Special Issue Microstructure and Mechanical Properties Analysis of Metallic Structural Materials)

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Open AccessArticle

Flexural Capacity of Concrete Beams with Basalt Fiber-Reinforced Polymer Bars and Stirrups

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Julita Krassowska

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Carolina Piña Ramírez

Materials 2022, 15(22), 8270; https://doi.org/10.3390/ma15228270 - 21 Nov 2022

Cited by 1 | Viewed by 1018

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The flexural properties of six 120 × 300 × 4500 mm concrete beams reinforced with bars made from basalt fiber-reinforced polymer (BFRP) basalt fibers and concrete stirrups were investigated. The beams contained different concrete compositions (with or without basalt fibers). Steel and BFRP [...] Read more.

The flexural properties of six 120 × 300 × 4500 mm concrete beams reinforced with bars made from basalt fiber-reinforced polymer (BFRP) basalt fibers and concrete stirrups were investigated. The beams contained different concrete compositions (with or without basalt fibers). Steel and BFRP bars were used as longitudinal and shear reinforcement. As expected, all the beams failed by the crushing of the concrete in the top compression fibers because of using BFRP bars. Beams with BFRP bars should be designed to fail by concrete crushing because it is safer than a brittle failure of the bars. The beams with composite reinforcement were characterized by the greatest number of cracks with the largest crack width. The use of basalt fibers resulted in slightly reduced cracks in beams. The most significant deflections were recorded for the beams with BFRC composite reinforcement, the smallest for FRC beams. Adding basalt fibers to the concrete resulted in slightly reduced deflection of FRC beams compared to RC beams and significantly reduced deflection compared to BFRC beams. Results showed that introducing basalt fibers to the concrete increased curvature ductility of these beams. A theoretical analysis of flexural capacity showed that the ACI standard design is more similar to experimental values (0.87). A more restrictive standard, as it turns out, is the fib Model Code (0.68). Full article

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Open AccessArticle

Attempt to Optimize the Corrosion Resistance of HRB400 Steel Rebar with Cr and RE

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Materials 2022, 15(22), 8269; https://doi.org/10.3390/ma15228269 - 21 Nov 2022

Viewed by 1008

Abstract

The corrosion resistance of the HRB400 steel rebar alloyed with Cr and rare earths (RE) was systematically studied from two aspects, including the properties of the passive film and the protectiveness of the rust layer. The results presented that Cr increased the corrosion [...] Read more.

The corrosion resistance of the HRB400 steel rebar alloyed with Cr and rare earths (RE) was systematically studied from two aspects, including the properties of the passive film and the protectiveness of the rust layer. The results presented that Cr increased the corrosion resistance of the steel rebar through stabilizing the passive film and was not involved in the formation of corrosion pits, while the pitting corrosion was initiated by the dissolution of (RE)₂O₂S inclusion, resulting in the local acidification at the bottom of the corrosion pits, which decreased the stability of the passive film. As for the long-term corrosion process, both Cr and RE decreased the corrosion rate of the steel rebar, which was related to the promotion effect on the formation of α-FeOOH in the rust layer from Cr and RE. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization - 2nd Volume)

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Open AccessEditor’s ChoiceArticle

Tailoring the Stability of Ti-Doped Sr₂Fe_1.4Ti_xMo_0.6−xO_6−δ Electrode Materials for Solid Oxide Fuel Cells

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Materials 2022, 15(22), 8268; https://doi.org/10.3390/ma15228268 - 21 Nov 2022

Viewed by 1113

Abstract

In this work, the stability of Sr₂(FeMo)O_6−δ-type perovskites was tailored by the substitution of Mo with Ti. Redox stable Sr₂Fe_1.4Ti_xMo_0.6−xO_6−δ (x = 0.1, 0.2 and 0.3) perovskites were successfully obtained [...] Read more.

In this work, the stability of Sr₂(FeMo)O_6−δ-type perovskites was tailored by the substitution of Mo with Ti. Redox stable Sr₂Fe_1.4Ti_xMo_0.6−xO_6−δ (x = 0.1, 0.2 and 0.3) perovskites were successfully obtained and evaluated as potential electrode materials for SOFCs. The crystal structure as a function of temperature, microstructure, redox stability, and thermal expansion properties in reducing and oxidizing atmospheres, oxygen content change, and transport properties in air and reducing conditions, as well as chemical stability and compatibility towards typical electrolytes have been systematically studied. All Sr₂Fe_1.4Ti_xMo_0.6−xO_6−δ compounds exhibit a regular crystal structure with Pm-3m space group, showing excellent stability in oxidizing and reducing conditions. The increase of Ti-doping content in materials increases the thermal expansion coefficient (TEC), oxygen content change, and electrical conductivity in air, while it decreases the conductivity in reducing condition. All three materials are stable and compatible with studied electrolytes. Interestingly, redox stable Sr₂Fe_1.4Ti_0.1Mo_0.5O_6−δ, possessing 1 μm grain size, low TEC (15.3 × 10⁻⁶ K⁻¹), large oxygen content change of 0.72 mol·mol⁻¹ between 30 and 900 °C, satisfactory conductivity of 4.1–7.3 S·cm⁻¹ in 5% H₂ at 600–800 °C, and good transport coefficients D and k, could be considered as a potential anode material for SOFCs, and are thus of great interest for further studies. Full article

(This article belongs to the Special Issue Feature Papers in Refractories and Ceramics: Microstructure, Properties and Applications)

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Open AccessArticle

Study on the Magnetic Noise Characteristics of Amorphous and Nanocrystalline Inner Magnetic Shield Layers of SERF Co-Magnetometer

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Materials 2022, 15(22), 8267; https://doi.org/10.3390/ma15228267 - 21 Nov 2022

Cited by 2 | Viewed by 1018

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With the widespread use of magneto-sensitive elements, magnetic shields are an important part of electronic equipment, ultra-sensitive atomic sensors, and in basic physics experiments. Particularly in Spin-exchange relaxation-free (SERF) co-magnetometers, the magnetic shield is an important component for maintaining the SERF state. However, [...] Read more.

With the widespread use of magneto-sensitive elements, magnetic shields are an important part of electronic equipment, ultra-sensitive atomic sensors, and in basic physics experiments. Particularly in Spin-exchange relaxation-free (SERF) co-magnetometers, the magnetic shield is an important component for maintaining the SERF state. However, the inherent noise of magnetic shield materials is an important factor limiting the measurement sensitivity and accuracy of SERF co-magnetometers. In this paper, both amorphous and nanocrystalline materials were designed and applied as the innermost magnetic shield of an SERF co-magnetometer. Magnetic noise characteristics of different amorphous and nanocrystalline materials used as the internal magnetic shielding layer of the magnetic shielding system were analyzed. In addition, the effects on magnetic noise due to adding aluminum to amorphous and nanocrystalline materials were studied. The experimental results show that compared with an amorphous material, a nanocrystalline material as the inner magnetic shield layer can effectively reduce the magnetic noise and improve the sensitivity and precision of the rotation measurement. Nanocrystalline material is very promising for inner shield composition in SERF co-magnetometers. Furthermore, its ultra-thin structure and low cost have significant application value in the miniaturization of SERF co-magnetometers. Full article

(This article belongs to the Special Issue Soft Magnetic Materials and Their Application)

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Open AccessArticle

Rheological Investigation of Welding Waste-Derived Graphene Oxide in Water-Based Drilling Fluids

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Materials 2022, 15(22), 8266; https://doi.org/10.3390/ma15228266 - 21 Nov 2022

Cited by 3 | Viewed by 1424

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Throughout the world, the construction industry produces significant amounts of by-products and hazardous waste materials. The steel-making industry generates welding waste and dusts that are toxic to the environment and pose many economic challenges. Water-based drilling fluids (WBDF) are able to remove the [...] Read more.

Throughout the world, the construction industry produces significant amounts of by-products and hazardous waste materials. The steel-making industry generates welding waste and dusts that are toxic to the environment and pose many economic challenges. Water-based drilling fluids (WBDF) are able to remove the drill cuttings in a wellbore and maintain the stability of the wellbore to prevent formation damage. To the best of our knowledge, this is the first study that reports the application of welding waste and its derived graphene oxide (GO) as a fluid-loss additive in drilling fluids. In this research, GO was successfully synthesized from welding waste through chemical exfoliation. The examination was confirmed using XRD, FTIR, FESEM and EDX analyses. The synthesized welding waste-derived GO in WBDF is competent in improving rheological properties by increasing plastic viscosity (PV), yield point (YP) and gel strength (GS), while reducing filtrate loss (FL) and mud cake thickness (MCT). This study shows the effect of additives such as welding waste, welding waste-derived GO and commercial GO, and their amount, on the rheological properties of WBDF. Concentrations of these additives were used at 0.01 ppb, 0.1 ppb and 0.5 ppb. Based on the experiment results, raw welding waste and welding waste-derived GO showed better performance compared with commercial GO. Among filtration properties, FL and MCT were reduced by 33.3% and 39.7% with the addition of 0.5 ppb of raw welding-waste additive, while for 0.5 ppb of welding waste-derived GO additive, FL and MCT were reduced by 26.7% and 20.9%, respectively. By recycling industrial welding waste, this research conveys state-of-the-art and low-cost drilling fluids that aid in waste management, and reduce the adverse environmental and commercial ramifications of toxic wastes. Full article

(This article belongs to the Special Issue Advanced Graphene and Graphene Oxide Materials)

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Open AccessArticle

Line Shape Analysis and Dynamic Response of Ballastless Track during Jacking Rectification Fixing

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Materials 2022, 15(22), 8265; https://doi.org/10.3390/ma15228265 - 21 Nov 2022

Viewed by 832

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In order to study the railway line deformation and dynamic response of ballastless track structure under train load during jacking rectification fixing, a three-dimensional numerical model of the CRTS II slab ballastless track on subgrade is established by using the finite element method. [...] Read more.

In order to study the railway line deformation and dynamic response of ballastless track structure under train load during jacking rectification fixing, a three-dimensional numerical model of the CRTS II slab ballastless track on subgrade is established by using the finite element method. The line deformation rule and local damage rule of ballastless track under jacking force are analyzed. The dynamic response laws of track structure and subgrade bed are compared considering four different connection modes between the base plate and subgrade bed under different train speeds in the process of jacking rectification fixing. The results show that jacking force and dissociation length have a small influence on the deviation value and the critical jacking force should be smaller than 375 kN in single point jacking. Under the condition of multi-point jacking, when the jacking loading length equals to 5 slabs, the critical jacking force should be smaller than 275 kN and the maximum lateral deviation value is about 22.11 mm. It is necessary to restrict the speed of passing trains to no more than 150 km/h during the jacking rectification fixing for dissociation condition without temporary restraint. When temporary restraint is applied, the speed of the train can be increased appropriately according to the actual situation. The above study results could be used as a theoretical reference for the ballastless track deviation correction. Full article

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Open AccessArticle

Dynamic Compressive and Tensile Characterisation of Igneous Rocks Using Split-Hopkinson Pressure Bar and Digital Image Correlation

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Albin Wessling

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Jörgen Kajberg

Materials 2022, 15(22), 8264; https://doi.org/10.3390/ma15228264 - 21 Nov 2022

Cited by 1 | Viewed by 1005

Abstract

The dynamic fracture process of rock materials is of importance for several industrial applications, such as drilling for geothermal installation. Numerical simulation can aid in increasing the understanding about rock fracture; however, it requires precise knowledge about the dynamical mechanical properties alongside information [...] Read more.

The dynamic fracture process of rock materials is of importance for several industrial applications, such as drilling for geothermal installation. Numerical simulation can aid in increasing the understanding about rock fracture; however, it requires precise knowledge about the dynamical mechanical properties alongside information about the initiation and propagation of cracks in the material. This work covers the detailed dynamic mechanical characterisation of two rock materials—Kuru grey granite and Kuru black diorite—using a Split-Hopkinson Pressure Bar complemented with high-speed imaging. The rock materials were characterised using the Brazilian disc and uniaxial compression tests. From the high-speed images, the instant of fracture initiation was estimated for both tests, and a Digital Image Correlation analysis was conducted for the Brazilian disc test. The nearly constant tensile strain in the centre was obtained by selecting a rectangular sensing region, sufficiently large to avoid complicated local strain distributions appearing between grains and at voids. With a significantly high camera frame rate of 671,000 fps, the indirect tensile strain and strain rates on the surface of the disc could be evaluated. Furthermore, the overloading effect in the Brazilian disc test is evaluated using a novel methodology consisting of high-speed images and Digital Image Correlation analysis. From this, the overloading effects were found to be 30 and 23%. The high-speed images of the compression tests indicated fracture initiation at 93 to 95% of the peak dynamic strength for granite and diorite, respectively. However, fracture initiation most likely occurred before this in a non-observed part of the sample. It is concluded that the indirect tensile strain obtained by selecting a proper size of the sensing region combined with the high temporal resolution result in a reliable estimate of crack formation and subsequent propagation. Full article

(This article belongs to the Section Advanced Materials Characterization)

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Open AccessEditor’s ChoiceArticle

Development of Root Caries Prevention by Nano-Hydroxyapatite Coating and Improvement of Dentin Acid Resistance

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Miyu Iwasaki

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Ryouichi Satou

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Naoki Sugihara

Materials 2022, 15(22), 8263; https://doi.org/10.3390/ma15228263 - 21 Nov 2022

Cited by 1 | Viewed by 1095

Abstract

There is no established method for optimizing the use of dentin to prevent root caries, which are increasing in the elderly population. This study aimed to develop a new approach for root caries prevention by focusing on bioapatite (BioHap), a new biomaterial, combined [...] Read more.

There is no established method for optimizing the use of dentin to prevent root caries, which are increasing in the elderly population. This study aimed to develop a new approach for root caries prevention by focusing on bioapatite (BioHap), a new biomaterial, combined with fluoride. Bovine dentin was used as a sample, and an acid challenge was performed in three groups: no fluoride (control group), acidulated phosphate fluoride treatment (APF group), and BioHap + APF treatment (BioHap group). After applying the new compound, the acid resistance of dentin was compared with that of APF alone. The BioHap group had fewer defects and an increased surface hardness than the APF group. The BioHap group had the smallest lesion depth and least mineral loss among all groups. Using a scanning electron microscope in the BioHap group showed the closure of dentinal tubules and a coating on the surface. The BioHap group maintained a coating and had higher acid resistance than the APF group. The coating prevents acid penetration, and the small particle size of BioHap and its excellent reactivity with fluoride are thought to have contributed to the improvement of acid resistance in dentin. Topical fluoride application using BioHap protects against root caries. Full article

(This article belongs to the Special Issue Materials for Hard Tissue Repair and Regeneration (Second Volume))

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Open AccessArticle

Effect of Contact Point of Wire Ring on Cooling Behavior during Stelmor Cooling

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Joong-Ki Hwang

Materials 2022, 15(22), 8262; https://doi.org/10.3390/ma15228262 - 21 Nov 2022

Viewed by 1280

Abstract

The influence of the contact point of wire rod on the inhomogeneity of cooling behavior within wire ring was investigated to reveal the fundamental cooling mechanism of wire rod during the Stelmor cooling process. A hotspot, a relatively high-temperature region within wire ring [...] Read more.

The influence of the contact point of wire rod on the inhomogeneity of cooling behavior within wire ring was investigated to reveal the fundamental cooling mechanism of wire rod during the Stelmor cooling process. A hotspot, a relatively high-temperature region within wire ring compared with other regions, was generated in both the central (WR_c) and edge (WR_e) regions of the wire ring. The WR_e exhibited hotspots regardless of ring configuration. Meanwhile, the WR_c exhibited hotspots with an inline arrangement; otherwise, no hotspot occurred in the WR_c with a staggered arrangement. Compared with the middle regions of the wire ring, hotspots easily occurred at both the WR_c and WR_e due to the low-contact angle of the two wire rings. Moreover, the possibility of hotspot formation increased with increasing wire diameter due to the high-contact area and load caused by the weight of the wire rod. This is the primary reason why the WR_c with a large diameter had hotspots despite the large ring pitch. Three solutions were suggested to improve the homogeneity in the mechanical properties within wire ring. Full article

(This article belongs to the Topic Modern Material Technologies Intended for Industrial Applications)

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Open AccessArticle

Design and Application of a Twisted and Coiled Polymer Driven Artificial Musculoskeletal Actuation Module

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Materials 2022, 15(22), 8261; https://doi.org/10.3390/ma15228261 - 21 Nov 2022

Viewed by 837

Abstract

Twisted and coiled polymer (TCP) artificial muscles can exhibit unidirectional actuation similar to skeletal muscles. This paper presents a TCP driven artificial musculoskeletal actuation module that can be used in soft robots. This module can contract in the axis direction, and the contraction [...] Read more.

Twisted and coiled polymer (TCP) artificial muscles can exhibit unidirectional actuation similar to skeletal muscles. This paper presents a TCP driven artificial musculoskeletal actuation module that can be used in soft robots. This module can contract in the axis direction, and the contraction displacement and force can be controlled easily. The main body of the actuation module consists of TCP muscles and leaf springs, and the deformation of the module is actuated by the TCP muscles. A prototype was made to test the performance of the module. The design and experimental results of the module are presented. The module can provide contraction motion. Results show that the module can provide a contraction force of 0.7 N with displacement of approximately 6.8 mm at 120 °C when exposed to electrical power of 24 V. The proposed artificial musculoskeletal actuation module can potentially be applied in biomimetic robots and the aerospace field. Full article

(This article belongs to the Special Issue Advanced Composite Material Design and Manufacturing Technology for Aerospace Engineering)

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Open AccessArticle

Multi-Function Reflective Vector Light Fields Generated by All-Dielectric Encoding Metasurface

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Materials 2022, 15(22), 8260; https://doi.org/10.3390/ma15228260 - 21 Nov 2022

Viewed by 965

Abstract

Traditional optics usually studies the uniform polarization state of light. Compared with uniform vector beams, non-uniform vector beams have more polarization information. Most of the research on generating cylindrical vector beams using metasurfaces focuses on generating transmitted beams using the geometric phase. However, [...] Read more.

Traditional optics usually studies the uniform polarization state of light. Compared with uniform vector beams, non-uniform vector beams have more polarization information. Most of the research on generating cylindrical vector beams using metasurfaces focuses on generating transmitted beams using the geometric phase. However, the geometric phase requires the incident light to be circularly polarized, which limits the design freedom. Here, an all-dielectric reflective metasurface is designed to generate different output light according to the different polarization states of the incident light. By combining the two encoding arrangements of the dynamic phase and the geometric phase, the output light is a radial vector beam when the linearly polarized light is incident along the x-direction. Under the incidence of linearly polarized light along the y-direction, the generated output light is an azimuthal vector beam. Under the incidence of left-handed circularly polarized light, the generated output light is a vortex beam with a topological charge of −1. Under the incidence of right-handed circularly polarized light, the generated output light is a vortex beam with a topological charge of +1. The proposed reflective metasurface has potential applications in generating vector beams with high integration. Full article

(This article belongs to the Special Issue Metamaterials and Metasurfaces: Fundamentals and Applications)

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Open AccessArticle

Selected Shear Models Based on the Analysis of the Critical Shear Crack for Slender Concrete Beams without Shear Reinforcement

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Monika Kaszubska

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Renata Kotynia

Materials 2022, 15(22), 8259; https://doi.org/10.3390/ma15228259 - 21 Nov 2022

Viewed by 946

Abstract

This paper is devoted to the shear of slender concrete beams flexurally reinforced with two types of reinforcement: steel and fiber-reinforced polymer (FRP) without transversal reinforcement. The paper presents four theoretical models for calculating the shear capacity of the collected test database and [...] Read more.

This paper is devoted to the shear of slender concrete beams flexurally reinforced with two types of reinforcement: steel and fiber-reinforced polymer (FRP) without transversal reinforcement. The paper presents four theoretical models for calculating the shear capacity of the collected test database and the authors’ own research program, which contained 29 single-span, simply supported T-section beams reinforced with steel and glass fiber-reinforcement polymer (GFRP) bars. The paper presents a comprehensive analysis of the test results and modeling of design shear capacity in accordance with the selected theoretical models. The generalized assessment of computational analysis confirmed compatibility of the predicted and experimental results. Full article

(This article belongs to the Special Issue Advanced Construction Materials and Processes in Poland)

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Open AccessArticle

Quantification of Microstructural Changes in the Dermis of Elderly Women Using Morphometric Indices of the Skin Surface

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Materials 2022, 15(22), 8258; https://doi.org/10.3390/ma15228258 - 21 Nov 2022

Viewed by 981

Abstract

Objective: The main objective of this study was the development of a non-invasive mathematical marker of the skin surface, the characteristic length, to predict the microstructure of the dermis. This marker, at the individual level, is intended to provide the biological age of [...] Read more.

Objective: The main objective of this study was the development of a non-invasive mathematical marker of the skin surface, the characteristic length, to predict the microstructure of the dermis. This marker, at the individual level, is intended to provide the biological age of the patient in the context of personalised medicine for the elderly. Study design: To validate this hypothesis, a clinical study was conducted on 22 women over 60 years old from a population of osteoporotic subjects who sustained a femoral neck fracture: a morphological analysis of the skin surface was performed on the patient’s forearm and quantitatively compared with microarchitectural parameters of the dermis. Major results: The Elastin-to-Collagen ratio measured on dermis samples ranged between 0.007 and 0.084, with a mean of 0.035 ± 0.02. The surface characteristic length ranged between 0.90 and 2.621, with a mean of 0.64 ± 0.51. A very strong correlation was found between this characteristic length and the Elastin-to-Collagen ratio (r = 0.92). Conclusions: This study proposes an original diagnostic tool based on morphometric indices of the skin surface and shows a direct quantitative relationship with the dermis microarchitecture and its collagen and elastin content. The proposed method allows reliable and easy access to the intrinsic ageing of the dermis, which would be a strong biomarker in a personalised collagen treatment approach. Full article

(This article belongs to the Special Issue Microstructure and Biomechanical Behavior of Living Tissues)

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Open AccessArticle

Numerical Simulation of the Impact of Water Vapour and Moisture Blockers in Energy Diagnostics of Ventilated Partitions

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Barbara Ksit

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Anna Szymczak-Graczyk

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Roman Pilch

Materials 2022, 15(22), 8257; https://doi.org/10.3390/ma15228257 - 21 Nov 2022

Cited by 2 | Viewed by 909

Abstract

Current trends towards saving energy and designing sustainable buildings result in most designers focusing on achieving the best thermal parameters, thereby neglecting a careful moisture analysis. Excessive moisture content in building partitions degrades the mechanical properties of materials, reduces thermal insulation properties (which [...] Read more.

Current trends towards saving energy and designing sustainable buildings result in most designers focusing on achieving the best thermal parameters, thereby neglecting a careful moisture analysis. Excessive moisture content in building partitions degrades the mechanical properties of materials, reduces thermal insulation properties (which leads to an increase in the demand for thermal energy) and worsens the microclimate in rooms. Modern digital solutions help create appropriate models of partitions that work for many years in good environmental conditions. According to the analysis of air parameters, 1 m³ of air at 20 °C contains approx. 17.3 g of water. When the temperature of the air reaches the dew point temperature, water vapour condenses. The dew point depends on air temperature and relative air humidity; for instance, at the same air temperature of 20 °C, the dew point temperature at 40% relative air humidity is 6 °C, whereas at 90% relative humidity, it is over 18 °C. This means that the higher the value of relative humidity in the room at a certain temperature, the lower the temperature that will cause condensation. The article presents a numerical analysis of the insulation work of flexible materials within the layers of ventilated partitions in an 8-year simulated period of varying environmental conditions. The aim of the article is to analyze different models and variants of ventilated partition operation with respect to the advisability of using a vapour barrier to avoid the problem of destruction of thermal insulation and finishing layers of a ventilated roof. Full article

(This article belongs to the Special Issue Experimental Research and Computational Analysis of Eco- and Bio-Materials)

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Open AccessReview

Research Progress of Wide Tunable Bragg Grating External Cavity Semiconductor Lasers

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Materials 2022, 15(22), 8256; https://doi.org/10.3390/ma15228256 - 21 Nov 2022

Cited by 1 | Viewed by 1547

Abstract

In this paper, we review the progress of wide tunable Bragg grating external cavity semiconductor lasers (BG-ECSLs). We concentrate on BG-ECSLs based on the wide tunable range for multicomponent detection. Wide tunable BG-ECSLs have many important applications, such as wavelength-division multiplexing (WDM) systems, [...] Read more.

In this paper, we review the progress of wide tunable Bragg grating external cavity semiconductor lasers (BG-ECSLs). We concentrate on BG-ECSLs based on the wide tunable range for multicomponent detection. Wide tunable BG-ECSLs have many important applications, such as wavelength-division multiplexing (WDM) systems, coherent optical communications, gas detection and atom cooling. Wide tunability, narrow linewidth and a high side-mode suppression ratio BG-ECSLs have attracted much attention for their merits. In this paper, three main structures for achieving widely tunable, narrow linewidth, high side-mode suppression ratio BG-ECSLs are reviewed and compared in detail, such as the volume Bragg grating (VBG) structure, fiber Bragg grating (FBG) structure and waveguide Bragg grating (WBG) structure of ECSLs. The advantages and disadvantages of different structures of BG-ECSLs are analyzed. The results show that WBG-ECSLs are a potential way to realize the integration, small size, wide tuning range, stable spectral output and high side-mode suppression ratio laser output. Therefore, the use of WBG as optical feedback elements is still the mainstream direction of BG-ECSLs, and BG-ECSLs offer a further new option for multicomponent detection and multi-atoms cooling. Full article

(This article belongs to the Special Issue Semiconductor Optoelectronic Materials and Devices)

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Open AccessEditor’s ChoiceArticle

Hydroxyapatite Affects the Physicochemical Properties of Contemporary One-Step Self-Etch Adhesives

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Materials 2022, 15(22), 8255; https://doi.org/10.3390/ma15228255 - 21 Nov 2022

Viewed by 1509

Abstract

The study aimed to evaluate the influence of the manipulation surfaces on the physical properties of one-step self-etch adhesives (1-SEAs). Scotchbond Universal (SBU), Clearfil Universal Bond Quick ER (UBQ), and an experimental adhesive (UBQ_exp) were manipulated on different surfaces: manufacturer’s Teflon-based [...] Read more.

The study aimed to evaluate the influence of the manipulation surfaces on the physical properties of one-step self-etch adhesives (1-SEAs). Scotchbond Universal (SBU), Clearfil Universal Bond Quick ER (UBQ), and an experimental adhesive (UBQ_exp) were manipulated on different surfaces: manufacturer’s Teflon-based dispensing dish (TD) or hydroxyapatite plate (HA). After manipulation of the adhesives, the pH of each 1-SEA was measured. Samples of each adhesive/manipulation surface were prepared and subjected to water sorption (WS)/solubility (SL) and flexural strength tests. The modulus of elasticity (E) was measured in dry and wet conditions before and after 24 h water storage, and the percentage of variation of E (ΔE) was calculated. Results were analyzed using the t-test with Bonferroni corrections (α = 0.05). When adhesives were manipulated on the HA plate, there was a significant increase in the adhesives’ pH. WS and SL of all 1-SEAs decreased when the HA was used. Only SBU showed higher flexural strength when manipulated on the HA compared to the manipulation on TD under dry and wet conditions. For each 1-SEA, the use of HA resulted in significantly higher E in dry and wet conditions. ΔE of all adhesives was smaller with the manipulation on HA than on TD. It was concluded that the manipulation of 1-SEA on a hydroxyapatite plate considerably affected the adhesives’ properties. Full article

(This article belongs to the Special Issue Unraveling the Properties of Tooth Adhesive Interfaces for the Benefit of the Longevity of Restorations)

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Open AccessArticle

Development of a CT Image Analysis Model for Cast Iron Products Based on Artificial Intelligence Methods

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Dorota Wilk-Kołodziejczyk

Materials 2022, 15(22), 8254; https://doi.org/10.3390/ma15228254 - 21 Nov 2022

Viewed by 907

Abstract

This paper presents an assessment of the possibility of using digital image classifiers for tomographic images concerning ductile iron castings. The results of this work can help the development of an efficient system suggestion allowing for decision making regarding the qualitative assessment of [...] Read more.

This paper presents an assessment of the possibility of using digital image classifiers for tomographic images concerning ductile iron castings. The results of this work can help the development of an efficient system suggestion allowing for decision making regarding the qualitative assessment of the casting process parameters. Special attention should be focused on the fact that automatic classification in the case of ductile iron castings is difficult to perform. The biggest problem in this aspect is the high similarity of the void image, which may be a sign of a defect, and the nodular graphite image. Depending on the parameters, the tests on different photos may look similar. Presented in this article are test scenarios of the module analyzing two-dimensional tomographic images focused on the comprehensive assessment by convolutional neural network models, which are designed to classify the provided image. For the purposes of the tests, three such models were created, different from each other in terms of architecture and the number of hyperparameters and trainable parameters. The described study is a part of the decision-making system, supporting the process of qualitative analysis of the obtained cast iron castings. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Machine Learning in Materials Science and Engineering)

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Open AccessArticle

A Cross-Scale Framework for Modelling Chloride Ions Diffusion in C-S-H: Combined Effects of Slip, Electric Double Layer and Ion Correlation

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Materials 2022, 15(22), 8253; https://doi.org/10.3390/ma15228253 - 21 Nov 2022

Viewed by 1097

Abstract

Water and chloride ions within pores of cementitious materials plays a crucial role in the damage processes of cement pastes, particularly in the binding material comprising calcium-silicate-hydrates (C-S-H). The migration mechanism of water and chloride ions restricted in C-S-H nanopores is complicated due [...] Read more.

Water and chloride ions within pores of cementitious materials plays a crucial role in the damage processes of cement pastes, particularly in the binding material comprising calcium-silicate-hydrates (C-S-H). The migration mechanism of water and chloride ions restricted in C-S-H nanopores is complicated due to the presence of interfacial effects. The special mechanical properties of the solid–liquid interface determine the importance of boundary slip and Electric Double Layer (EDL) and ion diversity in pore solutions determines the difference of the EDL and the stability of water film slip. A cross-scale model covering slip effects, time-varying of EDL and ion correlation needs to be developed so that the interfacial effects concentrated at the pore scale can be extended to affect the overall diffusivity of C-S-H. The statistics of pore size distribution and fractal dimension were used to quantitatively compare the similarities between model and C-S-H structure, thus proving the reliability of cross-scale reconstructed C-S-H transmission model. The results show that the slip effect is the dominant factor affecting the diffusion ability of C-S-H, the contribution of the slip effect is up to 60% and the contribution rate of EDL time-varying only up to about 15%. Moreover, the slip effect is sensitive to both ion correlation and C-S-H inhomogeneity and EDL time-varying is almost insensitive to ion correlation changes. This quantification provides a necessary benchmark for understanding the destructiveness of cement-based materials in the salt rich environment and provides new insights into improving the durability of concrete by changing the solid–liquid interface on the micro-nanoscale. Full article

(This article belongs to the Special Issue Concrete Durability: Deterioration Mechanisms, Prediction and Rehabilitation)

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Open AccessArticle

Investigating Residual Stresses in Metal-Plastic Composites Stiffening Ribs Formed Using the Single Point Incremental Forming Method

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Materials 2022, 15(22), 8252; https://doi.org/10.3390/ma15228252 - 21 Nov 2022

Cited by 5 | Viewed by 1370

Abstract

Low weight and high strength are significant factors in the current decade’s spread of composite sandwich materials. Previous studies have proven that forming stiffening ribs in these materials through the Single Point Incremental Forming (SPIF) process is possible and gives encouraging results. On [...] Read more.

Low weight and high strength are significant factors in the current decade’s spread of composite sandwich materials. Previous studies have proven that forming stiffening ribs in these materials through the Single Point Incremental Forming (SPIF) process is possible and gives encouraging results. On the other hand, knowledge of residual stress (RS) values that form during the manufacturing process is essential, as they may affect the structural integrity of manufactured elements, whether in compression or tension. The investigation of the RS in the composite materials formed by the SPIF process using the XRD method was very limited in the previous studies, so this research aims to apply the X-ray diffraction (XRD) method to determine RS on the part of the LITECOR^® sandwich material formed using SPIF. LITECOR^® consists of a plastic core between two layers of steel. In this study, three types of LITECOR^® were used with differing plastic core thicknesses of 0.8, 1.25, and 1.6 mm, while the steel layers’ thickness remained the same at 0.3 mm. The axial and traverse RSs were measured in five positions on both sides of the formed part. It was found that the achieved RSs varied from tensile to compressive along the formed regions. It was found that the residual stress values in both directions were inversely proportional to the thickness of the plastic core. It was noted that the highest RS values were in the unformed base metal, after which the RS was reduced on both sides of the SPIF-formed region, followed by a rise in the RS at the concave of the SPIF-formed region. The maximum measured RS for X-axes was 1041 MPa, whereas, for Y-axes, it was 1260 MPa, both of which were recorded on the back side at a thickness of t = 0.8 mm. Full article

(This article belongs to the Topic Manufacturing and Processing of Materials for Transport Industry)

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Open AccessArticle

Computational and Experimental Investigation of the Selective Adsorption of Indium/Iron Ions by the Epigallocatechin Gallate Monomer

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Materials 2022, 15(22), 8251; https://doi.org/10.3390/ma15228251 - 21 Nov 2022

Cited by 2 | Viewed by 985

Abstract

Selective recovery of indium has been widely studied to improve the resource efficiency of critical metals. However, the interaction and selective adsorption mechanism of indium/iron ions with tannin-based adsorbents is still unclear and hinders further optimization of their selective adsorption performance. In this [...] Read more.

Selective recovery of indium has been widely studied to improve the resource efficiency of critical metals. However, the interaction and selective adsorption mechanism of indium/iron ions with tannin-based adsorbents is still unclear and hinders further optimization of their selective adsorption performance. In this study, the epigallocatechin gallate (EGCG) monomer, which is the key functional unit of persimmon tannin, was chosen to explore the ability and mechanism of selective separation/extraction of indium from indium–iron mixture solutions. The density functional theory calculation results indicated that the deprotonated EGCG was easier to combine with indium/iron cations than those of un-deprotonated EGCG. Moreover, the interaction of the EGCG–Fe(III) complex was dominated by chelation and electrostatic interaction, while that of the EGCG–In(III) complex was controlled by electrostatic interactions and aromatic ring stacking effects. Furthermore, the calculation of binding energy verified that EGCG exhibited a stronger affinity for Fe(III) than that for In(III) and preferentially adsorbed iron ions in acidic or neutral solutions. Further experimental results were consistent with the theoretical study, which showed that the Freundlich equilibrium isotherm fit the In(III) and Fe(III) adsorption behavior very well, and the Fe(III) adsorption processes followed a pseudo-second-order model. Thermodynamics data revealed that the adsorption of In(III) and Fe(III) onto EGCG was feasible, spontaneous, and endothermic. The adsorption rate of the EGCG monomer for Fe(III) in neutral solution (1:1 mixed solution, pH = 3.0) was 45.7%, 4.3 times that of In(III) (10.7%). This study provides an in-depth understanding of the relationship between the structure of EGCG and the selective adsorption capacity at the molecular level and provides theoretical guidance for further optimization of the selective adsorption performance of structurally similar tannin-based adsorbents. Full article

(This article belongs to the Special Issue Synthesis, Optimization, and Reuse of Sustainable Bio-Based Materials)

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Open AccessReview

Properties and Applications of Geopolymer Composites: A Review Study of Mechanical and Microstructural Properties

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Ahmed Saeed

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Hadee Mohammed Najm

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Amer Hassan

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Mohanad Muayad Sabri Sabri

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Shaker Qaidi

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Nuha S. Mashaan

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Khalid Ansari

Materials 2022, 15(22), 8250; https://doi.org/10.3390/ma15228250 - 21 Nov 2022

Cited by 16 | Viewed by 2044

Abstract

Portland cement (PC) is considered the most energy-intensive building material and contributes to around 10% of global warming. It exacerbates global warming and climate change, which have a harmful environmental impact. Efforts are being made to produce sustainable and green concrete as an [...] Read more.

Portland cement (PC) is considered the most energy-intensive building material and contributes to around 10% of global warming. It exacerbates global warming and climate change, which have a harmful environmental impact. Efforts are being made to produce sustainable and green concrete as an alternative to PC concrete. As a result, developing a more sustainable strategy and eco-friendly materials to replace ordinary concrete has become critical. Many studies on geopolymer concrete, which has equal or even superior durability and strength compared to traditional concrete, have been conducted for this purpose by many researchers. Geopolymer concrete (GPC) has been developed as a possible new construction material for replacing conventional concrete, offering a clean technological choice for long-term growth. Over the last few decades, geopolymer concrete has been investigated as a feasible green construction material that can reduce CO₂ emissions because it uses industrial wastes as raw materials. GPC has proven effective for structural applications due to its workability and analogical strength compared to standard cement concrete. This review article discusses the engineering properties and microstructure of GPC and shows its merits in construction applications with some guidelines and suggestions recommended for both the academic community and the industrial sector. This literature review also demonstrates that the mechanical properties of GPC are comparable and even sometimes better than those of PC concrete. Moreover, the microstructure of GPC is significantly different from that of PC concrete microstructure and can be affected by many factors. Full article

(This article belongs to the Special Issue The Necessity and Feasibility of Innovative Waste-Derived Sustainable Construction Materials)

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Open AccessArticle

Effect of BASC and BASCA Heat Treatment on Microstructure and Mechanical Properties of TC10 Titanium Alloy

by

Mingyu Zhang

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Xinbing Yun

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Hongwang Fu

Materials 2022, 15(22), 8249; https://doi.org/10.3390/ma15228249 - 21 Nov 2022

Viewed by 973

Abstract

The purpose of this study is to investigate two new heat treatment processes on the mechanical properties of TC10 titanium alloy. By changing the β annealing temperature, the variation in microstructure and mechanical properties of TC10 titanium alloy were investigated. The results showed [...] Read more.

The purpose of this study is to investigate two new heat treatment processes on the mechanical properties of TC10 titanium alloy. By changing the β annealing temperature, the variation in microstructure and mechanical properties of TC10 titanium alloy were investigated. The results showed that with the increase in β annealing temperature the microstructure type changes from an equiaxed structure to a lamellar structure. The strength of the alloy then increases firstly, followed by a decrease, while the plasticity decreases all the time. Microstructure observation revealed that the alloy is uniformly composed of α phase and β phase after the two processes. In addition, it was found that the fracture morphology of the equiaxed structure is mainly dimples, showing ductile fracture characteristics, while the fracture morphology of lamellar microstructure is mainly crystalline, showing brittle fracture characteristics. These results indicated that reasonable β annealing temperature can be set according to different requirements to obtain different types of microstructure and mechanical properties, which expands the application field of TC10 titanium alloy. Full article

(This article belongs to the Special Issue Advanced Processing Methods for Metals and Their Alloys)

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Open AccessArticle

Assessment of Aging Impact on Wax Crystallization in Selected Asphalt Binders

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Materials 2022, 15(22), 8248; https://doi.org/10.3390/ma15228248 - 21 Nov 2022

Cited by 1 | Viewed by 995

Abstract

For a better understanding of the changing trend in crystalline components of asphalt binders, asphalt binders originating from the SHRP Materials Reference Library with different oxidation degrees (unaged, 20 h PAV, and 60 h PAV) were prepared. The native asphalt binders and their [...] Read more.

For a better understanding of the changing trend in crystalline components of asphalt binders, asphalt binders originating from the SHRP Materials Reference Library with different oxidation degrees (unaged, 20 h PAV, and 60 h PAV) were prepared. The native asphalt binders and their oxidized residues were characterized by liquid-state nuclear magnetic resonance (NMR) spectroscopy and high-temperature gas chromatography (HTGC). The results showed that, compared with other carbon types, the content of internal methylene carbons of long paraffinic chains between different SHRP binders was quite different. The NMR average length of a long paraffinic internal methylene chain showed a good correlation with the wax content obtained at −20 °C using the methyl ethyl ketone (MEK) precipitation method and also the recently developed variable-temperature Fourier-transform infrared spectroscopy (VT-FTIR) method. In most cases, the average length of straight internal methylene carbons of a long paraffinic chain terminated by a methyl group increased with the oxidation of the asphalt binder. However, the difference caused by oxidation was significantly smaller than the difference caused by the source of the asphalt binder. In general, oxidation will make the n-alkanes distributed in asphalt binder fall within a narrower range. The carbon number of n-alkanes in the asphalt binder generally grew with oxidation. Full article

(This article belongs to the Special Issue Performance-Related Material Properties of Asphalt Mixture Components)

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Open AccessEditor’s ChoiceArticle

Near-Infrared Artificial Optical Synapse Based on the P(VDF-TrFE)-Coated InAs Nanowire Field-Effect Transistor

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Materials 2022, 15(22), 8247; https://doi.org/10.3390/ma15228247 - 21 Nov 2022

Viewed by 1384

Abstract

Optical synapse is the basic component for optical neuromorphic computing and is attracting great attention, mainly due to its great potential in many fields, such as image recognition, artificial intelligence and artificial visual perception systems. However, optical synapse with infrared (IR) response has [...] Read more.

Optical synapse is the basic component for optical neuromorphic computing and is attracting great attention, mainly due to its great potential in many fields, such as image recognition, artificial intelligence and artificial visual perception systems. However, optical synapse with infrared (IR) response has rarely been reported. InAs nanowires (NWs) have a direct narrow bandgap and a large surface to volume ratio, making them a promising material for IR detection. Here, we demonstrate a near-infrared (NIR) (750 to 1550 nm) optical synapse for the first time based on a poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))-coated InAs NW field-effect transistor (FET). The responsivity of the P(VDF-TrFE)-coated InAs NW FET reaches 839.3 A/W under 750 nm laser illumination, demonstrating the advantage of P(VDF-TrFE) coverage. The P(VDF-TrFE)-coated InAs NW device exhibits optical synaptic behaviors in response to NIR light pulses, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF) and a transformation from short-term plasticity (STP) to long-term plasticity (LTP). The working mechanism is attributed to the polarization effect in the ferroelectric P(VDF-TrFE) layer, which dominates the trapping and de-trapping characteristics of photogenerated holes. These findings have significant implications for the development of artificial neural networks. Full article

(This article belongs to the Special Issue III-V Nanostructures and Their Devices)

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