Materials

16 pages, 5096 KiB

Open AccessArticle

Effect of Hydrothermal Factors on the Microhardness of Bulk-Fill and Nanohybrid Composites

by Daniel Pieniak, Agata M. Niewczas, Konrad Pikuła, Leszek Gil, Aneta Krzyzak, Krzysztof Przystupa, Paweł Kordos and Orest Kochan

Materials 2023, 16(5), 2130; https://doi.org/10.3390/ma16052130 - 6 Mar 2023

Viewed by 1998

Abstract

This study evaluates the effect of aging in artificial saliva and thermal shocks on the microhardness of the bulk-fill composite compared to the nanohybrid composite. Two commercial composites, Filtek Z550 (3M ESPE) (Z550) and Filtek Bulk-Fill (3M ESPE) (B-F), were tested. The samples [...] Read more.

This study evaluates the effect of aging in artificial saliva and thermal shocks on the microhardness of the bulk-fill composite compared to the nanohybrid composite. Two commercial composites, Filtek Z550 (3M ESPE) (Z550) and Filtek Bulk-Fill (3M ESPE) (B-F), were tested. The samples were exposed to artificial saliva (AS) for one month (control group). Then, 50% of the samples from each composite were subjected to thermal cycling (temperature range: 5–55 °C, cycle time: 30 s, number of cycles: 10,000) and another 50% were put back into the laboratory incubator for another 25 months of aging in artificial saliva. The samples’ microhardness was measured using the Knoop method after each stage of conditioning (after 1 month, after 10,000 thermocycles, after another 25 months of aging). The two composites in the control group differed considerably in hardness (HK = 89 for Z550, HK = 61 for B-F). After thermocycling, the microhardness decrease was for Z550 approximately 22–24% and for B-F approximately 12–15%. Hardness after 26 months of aging decreased for Z550 (approximately 3–5%) and B-F (15–17%). B-F had a significantly lower initial hardness than Z550, but it showed an approximately 10% lower relative reduction in hardness. Full article

(This article belongs to the Special Issue Properties of Dental Restorative Materials (Volume II))

► Show Figures

Figure 1

16 pages, 7644 KiB

Open AccessArticle

Acoustic Performance of Stress Gradient-Induced Deflection of Triangular Unimorphic/Bimorphic Cantilevers for MEMS Applications

by Ning-Hsiu Yuan, Chih-Chia Chen, Yiin-Kuen Fuh and Tomi T. Li

Materials 2023, 16(5), 2129; https://doi.org/10.3390/ma16052129 - 6 Mar 2023

Cited by 1 | Viewed by 1915

Abstract

This paper reports two piezoelectric materials of lead zirconium titanate (PZT) and aluminum nitride (AlN) used to simulate microelectromechanical system (MEMS) speakers, which inevitably suffered deflections as induced via the stress gradient during the fabrication processes. The main issue is the vibrated deflection [...] Read more.

This paper reports two piezoelectric materials of lead zirconium titanate (PZT) and aluminum nitride (AlN) used to simulate microelectromechanical system (MEMS) speakers, which inevitably suffered deflections as induced via the stress gradient during the fabrication processes. The main issue is the vibrated deflection from the diaphragm that influences the sound pressure level (SPL) of MEMS speakers. To comprehend the correlation between the geometry of the diaphragm and vibration deflection in cantilevers with the same condition of activated voltage and frequency, we compared four types of geometries of cantilevers including square, hexagon, octagon, and decagon in triangular membranes with unimorphic and bimorphic composition by utilizing finite element method (FEM) for physical and structural analyses. The size of different geometric speakers did not exceed 10.39 mm²; the simulation results reveal that under the same condition of activated voltage, the associated acoustic performance, such as SPL for AlN, is in good comparison with the simulation results of the published literature. These FEM simulation results of different types of cantilever geometries provide a methodology design toward practical applications of piezoelectric MEMS speakers in the acoustic performance of stress gradient-induced deflection in triangular bimorphic membranes. Full article

(This article belongs to the Special Issue Acoustic Properties of Materials)

► Show Figures

Figure 1

17 pages, 2666 KiB

Open AccessArticle

Acoustic Performance of Floors Made of Composite Panels

by Jacek Nurzyński and Łukasz Nowotny

Materials 2023, 16(5), 2128; https://doi.org/10.3390/ma16052128 - 6 Mar 2023

Cited by 3 | Viewed by 1932

Abstract

Airborne and impact sound insulation of composite panels arranged in different configurations were investigated in this study. The use of Fiber Reinforced Polymers (FRPs) in the building industry is growing; however, poor acoustic performance is a critical issue for their general employment in [...] Read more.

Airborne and impact sound insulation of composite panels arranged in different configurations were investigated in this study. The use of Fiber Reinforced Polymers (FRPs) in the building industry is growing; however, poor acoustic performance is a critical issue for their general employment in residential buildings. The study aimed to investigate possible methods of improvement. The principal research question involved the development of a composite floor satisfying acoustic expectations in dwellings. The study was based on the results of laboratory measurements. The airborne sound insulation of single panels was too low to meet any requirements. The double structure improved the sound insulation radically at middle and high frequencies but the single number values were still not satisfactory. Finally, the panel equipped with the suspended ceiling and floating screed achieved adequate level of performance. Regarding impact sound insulation, the lightweight floor coverings were ineffective and they even enhanced sound transmission in the middle frequency range. Heavy floating screeds behaved much better but the improvement was too small to satisfy acoustic requirements in residential buildings. The composite floor with a dry floating screed and a suspended ceiling appeared satisfactory with respect to airborne and impact sound insulation; the single number values were R_w (C; C_tr) = 61 (−2; −7) dB, and L_n,w = 49 dB, respectively. The results and conclusions outline directions for further development of an effective floor structure. Full article

(This article belongs to the Special Issue Advances in Sustainable Civil Engineering Materials)

► Show Figures

Figure 1

14 pages, 4467 KiB

Open AccessArticle

Grinding Burn Detection via Magnetic Barkhausen Noise Analysis Independently of Induction Hardened Depth

by Kizkitza Gurruchaga, Aitor Lasaosa, Itsaso Artetxe and Ane Martínez-de-Guerenu

Materials 2023, 16(5), 2127; https://doi.org/10.3390/ma16052127 - 6 Mar 2023

Cited by 2 | Viewed by 1662

Abstract

The electromagnetic technique based on magnetic Barkhausen noise (MBN) can be used to control the quality of ball screw shafts non-destructively, although identifying any slight grinding burns independently of induction-hardened depth remains a challenge. The capacity to detect slight grinding burns was studied [...] Read more.

The electromagnetic technique based on magnetic Barkhausen noise (MBN) can be used to control the quality of ball screw shafts non-destructively, although identifying any slight grinding burns independently of induction-hardened depth remains a challenge. The capacity to detect slight grinding burns was studied using a set of ball screw shafts manufactured by means of different induction hardening treatments and different grinding conditions (some of them under abnormal conditions for the purpose of generating grinding burns), and MBN measurements were taken in the whole group of ball screw shafts. Additionally, some of them were tested using two different MBN systems in order to better understand the effect of the slight grinding burns, while Vickers microhardness and nanohardness measurements were taken in selected samples. To detect the grinding burns (both slight anddata intense) with varying depths of the hardened layer, a multiparametric analysis of the MBN signal is proposed using the main parameters of the MBN two-peak envelope. At first, the samples are classified into groups depending on their hardened layer depth, estimated using the intensity of the magnetic field measured on the first peak (H1) parameter, and the threshold functions of two parameters (the minimum amplitude between the peaks of the MBN envelope (MIN) and the amplitude of the second peak (P2)) are then determined to detect the slight grinding burns for the different groups. Full article

(This article belongs to the Special Issue Electromagnetic Nondestructive Testing)

► Show Figures

Figure 1

15 pages, 2041 KiB

Open AccessArticle

Influence of Stretching on Liquid Transport in Knitted Fabrics

by Małgorzata Matusiak and Otgonsuren Sukhbat

Materials 2023, 16(5), 2126; https://doi.org/10.3390/ma16052126 - 6 Mar 2023

Cited by 2 | Viewed by 1579

Abstract

The transport of liquid sweat in clothing worn close to human skin is very important from the point of view of the thermo-physiological comfort of clothing users. It ensures the drainage of sweat secreted by the human body and condensed on the human [...] Read more.

The transport of liquid sweat in clothing worn close to human skin is very important from the point of view of the thermo-physiological comfort of clothing users. It ensures the drainage of sweat secreted by the human body and condensed on the human skin. In the presented work, knitted fabrics made of cotton and cotton blends with other fibers (elastane, viscose, polyester) were measured in the range of liquid moisture transport using the Moisture Management Tester MMT M290. The fabrics were measured in unstretched form and stretched to 15%. Stretching of the fabrics was performed using the MMT Stretch Fabric Fixture. Obtained results confirmed that stretching significantly changed the values of parameters characterizing the liquid moisture transport in the fabrics. Before stretching, the best liquid sweat transport performance was stated for the KF5 knitted fabric made of 54% cotton and 46% polyester. For this, the greatest value (10 mm) of maximum wetted radius for the bottom surface was obtained. The Overall Moisture Management Capacity (OMMC) of the KF5 fabric was 0.76. This was the highest value among all values obtained for the unstretched fabrics. The lowest value of the OMMC parameter (0.18) was stated for the KF3 knitted fabric. After stretching, the KF4 fabric variant was assessed as the best one. Its OMMC improved from 0.71 before stretching to 0.80 after stretching. The value of the OMMC for the KF5 fabric remained after stretching at the same level (0.77) than before stretching. The most significant improvement was observed for the KF2 fabric. Before stretching, the value of the OMMC parameter for the KF2 fabric was 0.27. After stretching, the OMMC value increased to 0.72. It was also stated that the changes in the liquid moisture transport performance of the investigated knitted fabrics were different for the particular fabrics being investigated. Generally, in all cases, the ability of the investigated knitted fabrics to transfer liquid sweat was improved after stretching. Full article

(This article belongs to the Section Advanced Materials Characterization)

► Show Figures

Figure 1

18 pages, 5896 KiB

Open AccessArticle

Effects of N-Alkanol Adsorption on Bubble Acceleration and Local Velocities in Solutions of the Homologous Series from Ethanol to N-Decanol

by Marcel Krzan, Pradipta Chattopadhyay, Sandra Orvalho and Maria Zednikova

Materials 2023, 16(5), 2125; https://doi.org/10.3390/ma16052125 - 6 Mar 2023

Cited by 2 | Viewed by 1353

Abstract

The influence of n-alkanol (C2–C10) water solutions on bubble motion was studied in a wide range of concentrations. Initial bubble acceleration, as well as local, maximal and terminal velocities during motion were studied as a function of motion time. Generally, two types of [...] Read more.

The influence of n-alkanol (C2–C10) water solutions on bubble motion was studied in a wide range of concentrations. Initial bubble acceleration, as well as local, maximal and terminal velocities during motion were studied as a function of motion time. Generally, two types of velocity profiles were observed. For low surface-active alkanols (C2–C4), bubble acceleration and terminal velocities diminished with the increase in solution concentration and adsorption coverage. No maximum velocities were distinguished. The situation is much more complicated for higher surface-active alkanols (C5–C10). In low and medium solution concentrations, bubbles detached from the capillary with acceleration comparable to gravitational acceleration, and profiles of the local velocities showed maxima. The terminal velocity of bubbles decreased with increasing adsorption coverage. The heights and widths of the maximum diminished with increasing solution concentration. Much lower initial acceleration values and no maxima presence were observed in the case of the highest n-alkanol concentrations (C5–C10). Nevertheless, in these solutions, the observed terminal velocities were significantly higher than in the case of bubbles moving in solutions of lower concentration (C2–C4). The observed differences were explained by different states of the adsorption layer in the studied solutions, leading to varying degrees of immobilization of the bubble interface, which generates other hydrodynamic conditions of bubble motion. Full article

(This article belongs to the Special Issue Advances in Soft Materials)

► Show Figures

Figure 1

19 pages, 14906 KiB

Open AccessArticle

Recycling of Tire-Derived Fiber: The Contribution of Steel Cord on the Properties of Lightweight Concrete Based on Perlite Aggregate

by Marta Kadela, Marcin Małek, Mateusz Jackowski, Mateusz Kunikowski, Agnieszka Klimek, Daniel Dudek and Marek Rośkowicz

Materials 2023, 16(5), 2124; https://doi.org/10.3390/ma16052124 - 6 Mar 2023

Cited by 4 | Viewed by 2694

Abstract

The increasing amount of waste from the vulcanization industry has become a serious environmental challenge. Even the partial reuse of the steel contained in tires as dispersed reinforcement in the production of new building materials may contribute to reducing the environmental impact of [...] Read more.

The increasing amount of waste from the vulcanization industry has become a serious environmental challenge. Even the partial reuse of the steel contained in tires as dispersed reinforcement in the production of new building materials may contribute to reducing the environmental impact of this industry while supporting the principle of sustainable development. In this study, the concrete samples were made of Portland cement, tap water, lightweight perlite aggregates, and steel cord fibers. Two different addition of steel cord fibers (1.3% and 2.6% wt. of concrete, respectively) were used. The samples of lightweight concrete based on perlite aggregate with steel cord fiber addition showed a significant increase in compressive (18–48%), tensile (25–52%), and flexural strength (26–41%). Moreover, higher thermal conductivity and thermal diffusivity were reported after incorporating steel cord fibers into the concrete matrix; however, the specific heat values decreased after these modifications. The highest values of thermal conductivity and thermal diffusivity were obtained for samples modified with a 2.6% addition of steel cord fibers and were equal to 0.912 ± 0.002 W/mK and 0.562 ± 0.002 µm²/s, respectively. Maximum specific heat, on the other hand, was reported for plain concrete (R)—1.678 ± 0.001 MJ/m³ K. Full article

(This article belongs to the Special Issue Advances in Sustainable Civil Engineering Materials)

► Show Figures

Figure 1

4 pages, 183 KiB

Open AccessEditorial

Mechanics and Analysis of Advanced Materials and Structures

by Sanichiro Yoshida and Giovanni Pappalettera

Materials 2023, 16(5), 2123; https://doi.org/10.3390/ma16052123 - 6 Mar 2023

Cited by 1 | Viewed by 1276

Abstract

Modern technological development has made the designing and characterization of materials sophisticated [...] Full article

(This article belongs to the Special Issue Mechanics and Analysis of Advanced Materials and Structures)

12 pages, 5600 KiB

Open AccessArticle

Influence of Polycaprolactone Concentration and Solvent Type on the Dimensions and Morphology of Electrosprayed Particles

by Laura Alberto, Lohitha Kalluri, Jing Qu, Yongfeng Zhao and Yuanyuan Duan

Materials 2023, 16(5), 2122; https://doi.org/10.3390/ma16052122 - 6 Mar 2023

Cited by 7 | Viewed by 2236

Abstract

Polycaprolactone (PCL) micro- and nanoparticles produced using the electrospraying technique present high drug encapsulation capacity, a controllable surface area, and a good cost–benefit ratio. PCL is also considered a non-toxic polymeric material with excellent biocompatibility and biodegradability. All these characteristics make PCL micro- [...] Read more.

Polycaprolactone (PCL) micro- and nanoparticles produced using the electrospraying technique present high drug encapsulation capacity, a controllable surface area, and a good cost–benefit ratio. PCL is also considered a non-toxic polymeric material with excellent biocompatibility and biodegradability. All these characteristics make PCL micro- and nanoparticles a promising material for tissue engineering regeneration, drug delivery, and surface modification in dentistry. In this study, PCL electrosprayed specimens were produced and analyzed to determine their morphology and size. Three PCL concentrations (2, 4, and 6 wt%) and three solvent types (chloroform (CF), dimethylformamide (DMF), and acetic acid (AA)) with various solvent mixtures ratios (1:1 CF/DMF, 3:1 CF/DMF, 100% CF, 1:1 AA/CF, 3:1 AA/CF, and 100% AA) were used while keeping the remaining electrospray parameters constant. SEM images followed by ImageJ analysis showed a change in the morphology and size of the particles among various tested groups. A two-way ANOVA demonstrated a statistically significant interaction (p < 0.001) between PCL concentration and solvents on the size of the particles. With the increase in the PCL concentration, an increase in the number of fibers was observed among all the groups. The morphology and dimensions of the electrosprayed particles, as well as the presence of fibers, were significantly dependent on the PCL concentration, choice of solvent, and solvent ratio. Full article

(This article belongs to the Special Issue Physical Properties and Biocompatibility of Restorative Dental Materials)

► Show Figures

Figure 1

14 pages, 10047 KiB

Open AccessArticle

Effect of Double-Step and Strain-Assisted Tempering on Properties of Medium-Carbon Steel

by Pavel Salvetr, Andrea Školáková, Jakub Kotous, Jan Drahokoupil, Daniel Melzer, Zdeněk Jansa, Črtomir Donik, Aleksandr Gokhman and Zbyšek Nový

Materials 2023, 16(5), 2121; https://doi.org/10.3390/ma16052121 - 6 Mar 2023

Cited by 3 | Viewed by 2108

Abstract

The present work aimed to study the properties of medium-carbon steel during tempering treatment and to present the strength increase of medium-carbon spring steels by strain-assisted tempering (SAT). The effect of double-step tempering and double-step tempering with rotary swaging, also known as SAT, [...] Read more.

The present work aimed to study the properties of medium-carbon steel during tempering treatment and to present the strength increase of medium-carbon spring steels by strain-assisted tempering (SAT). The effect of double-step tempering and double-step tempering with rotary swaging, also known as SAT, on the mechanical properties and microstructure was investigated. The main goal was to achieve a further enhancement of the strength of medium-carbon steels using SAT treatment. The microstructure consists of tempered martensite with transition carbides in both cases. The yield strength of the DT sample is 1656 MPa, while that of the SAT sample is about 400 MPa higher. On the contrary, plastic properties such as the elongation and reduction in area have lower values after SAT processing, about 3% and 7%, respectively, compared to the DT treatment. Grain boundary strengthening from low-angle grain boundaries can be attributed to the increase in strength. Based on X-ray diffraction analysis, a lower dislocation strengthening contribution was determined for the SAT sample compared to the double-step tempered sample. Full article

(This article belongs to the Special Issue Microstructure and Mechanical Properties Relationship for Metallic Materials)

► Show Figures

Figure 1

15 pages, 8668 KiB

Open AccessArticle

Microstructure and Ablation Behavior of C/C-SiC-(Zr_xHf_1−x)C Composites Prepared by Reactive Melt Infiltration Method

by Zaidong Liu, Yalei Wang, Xiang Xiong, Zhiyong Ye, Quanyuan Long, Jinming Wang, Tongqi Li and Congcong Liu

Materials 2023, 16(5), 2120; https://doi.org/10.3390/ma16052120 - 6 Mar 2023

Cited by 11 | Viewed by 2353

Abstract

C/C-SiC-(Zr_xHf_1−x)C composites were prepared by the reactive melt infiltration method. The microstructure of the porous C/C skeleton and the C/C-SiC-(Zr_xHf_1−x)C composites, as well as the structural evolution and ablation behavior of the C/C-SiC-(Zr_xHf [...] Read more.

C/C-SiC-(Zr_xHf_1−x)C composites were prepared by the reactive melt infiltration method. The microstructure of the porous C/C skeleton and the C/C-SiC-(Zr_xHf_1−x)C composites, as well as the structural evolution and ablation behavior of the C/C-SiC-(Zr_xHf_1−x)C composites, were systematically investigated. The results show that the C/C-SiC-(Zr_xHf_1−x)C composites were mainly composed of carbon fiber, carbon matrix, SiC ceramic, (Zr_xHf_1−x)C and (Zr_xHf_1−x)Si₂ solid solutions. The refinement of the pore structure is beneficial to promote the formation of (Zr_xHf_1−x)C ceramic. The C/C-SiC-(Zr_xHf_1−x)C composites exhibited outstanding ablation resistance under an air–plasma environment at around 2000 °C. After ablation for 60 s, CMC-1 appeared to possess the minimum mass and linear ablation rates of only 2.696 mg/s and −0.814 µm/s, respectively, which are lower than those of CMC-2 and CMC-3. During the ablation process, a Bi-liquid phase and a liquid–solid two-phase structure were formed on the ablation surface which could act as an oxygen diffusion barrier to retard further ablation, which is responsible for the excellent ablation resistance of the C/C-SiC-(Zr_xHf_1−x)C composites. Full article

(This article belongs to the Special Issue High-Performance Structural Ceramics and Hybrid Materials)

► Show Figures

Figure 1

11 pages, 1842 KiB

Open AccessArticle

The Ionization of Polymeric Materials Accelerates Protein Deposition on Hydrogel Contact Lens Material

by Jihye Ahn and Moonsung Choi

Materials 2023, 16(5), 2119; https://doi.org/10.3390/ma16052119 - 6 Mar 2023

Cited by 3 | Viewed by 1903

Abstract

Contact lens materials include polymers that are ionized in the ocular pH condition and are susceptible to protein deposition due to their surface characteristics. Herein, we investigated the effect of the electrostatic state of the contact lens material and protein on protein deposition [...] Read more.

Contact lens materials include polymers that are ionized in the ocular pH condition and are susceptible to protein deposition due to their surface characteristics. Herein, we investigated the effect of the electrostatic state of the contact lens material and protein on protein deposition level using hen egg white lysozyme (HEWL) and bovine serum albumin (BSA) as model proteins and etafilcon A and hilafilcon B as model contact lens materials. Only HEWL deposition on etafilcon A showed a statistically significant pH-dependency (p < 0.05); protein deposition increased with pH. HEWL showed a positive zeta potential at acidic pH, while BSA showed a negative zeta potential at basic pH. Only etafilcon A showed a statistically significant pH-dependent point of zero charge (PZC) (p < 0.05), implying that its surface charge became more negative under basic conditions. This pH-dependency of etafilcon A is attributed to the pH-responsive degree of ionization of its constituent methacrylic acid (MAA). The presence of MAA and its degree of ionization could accelerate protein deposition; more HEWL deposited as pH increased despite the weak positive surface charge of HEWL. The highly negatively charged etafilcon A surface attracted HEWL, even overwhelming weak positive charge of HEWL, increasing the deposition with pH. Full article

► Show Figures

Figure 1

13 pages, 6070 KiB

Open AccessArticle

Three-Dimensional Characterization of Polyurethane Foams Based on Biopolyols

by Lorenleyn De la Hoz Alford, Camila Gomes Peçanha de Souza, Sidnei Paciornik, José Roberto M. d’Almeida, Brenno Santos Leite, Harold C. Avila, Fabien Léonard and Giovanni Bruno

Materials 2023, 16(5), 2118; https://doi.org/10.3390/ma16052118 - 6 Mar 2023

Viewed by 2006

Abstract

Two biopolyol-based foams derived from banana leaves (BL) or stems (BS) were produced, and their compression mechanical behavior and 3D microstructure were characterized. Traditional compression and in situ tests were performed during 3D image acquisition using X-ray microtomography. A methodology of image acquisition, [...] Read more.

Two biopolyol-based foams derived from banana leaves (BL) or stems (BS) were produced, and their compression mechanical behavior and 3D microstructure were characterized. Traditional compression and in situ tests were performed during 3D image acquisition using X-ray microtomography. A methodology of image acquisition, processing, and analysis was developed to discriminate the foam cells and measure their numbers, volumes, and shapes along with the compression steps. The two foams had similar compression behaviors, but the average cell volume was five times larger for the BS foam than the BL foam. It was also shown that the number of cells increased with increasing compression while the average cell volume decreased. Cell shapes were elongated and did not change with compression. A possible explanation for these characteristics was proposed based on the possibility of cell collapse. The developed methodology will facilitate a broader study of biopolyol-based foams intending to verify the possibility of using these foams as green alternatives to the typical petrol-based foams. Full article

(This article belongs to the Special Issue Advanced Biopolymer Materials: Preparation, Characterization and Applications)

► Show Figures

Figure 1

13 pages, 2746 KiB

Open AccessArticle

An In Situ Prepared Comb-like Polycaprolactone-Based Gel Electrolyte for High-Performance Lithium Metal Batteries

by Yange Fan, Huifeng Wang, Shipeng Chen, Yimin Hou and Shujiang Wang

Materials 2023, 16(5), 2117; https://doi.org/10.3390/ma16052117 - 6 Mar 2023

Cited by 2 | Viewed by 2020

Abstract

Herein, we present the synthesis and electrochemical performance of a comb-like polycaprolactone-based gel electrolyte from acrylate terminated polycaprolactone oligomers and liquid electrolyte for high-voltage lithium metal batteries. The ionic conductivity of this gel electrolyte at room temperature was measured to be 8.8 × [...] Read more.

Herein, we present the synthesis and electrochemical performance of a comb-like polycaprolactone-based gel electrolyte from acrylate terminated polycaprolactone oligomers and liquid electrolyte for high-voltage lithium metal batteries. The ionic conductivity of this gel electrolyte at room temperature was measured to be 8.8 × 10⁻³ S cm⁻¹, which is an exceptionally high value that is more than sufficient for the stable cycling of solid-state lithium metal batteries. The Li⁺ transference number was detected to be 0.45, facilitating the prohibition of concentration gradients and polarization, thereby prohibiting lithium dendrite formation. In addition, the gel electrolyte exhibits high oxidation voltage up to 5.0 V vs. Li⁺/Li and perfect compatibility against metallic lithium electrodes. The superior electrochemical properties provide the LiFePO₄-based solid-state lithium metal batteries with excellent cycling stability, displaying a high initial discharge capacity of 141 mAh g⁻¹ and an extraordinary capacity retention exceeding 74% of its initial specific capacity after being cycled for 280 cycles at 0.5C at room temperature. This paper presents a simple and effective in situ preparation process yielding an excellent gel electrolyte for high-performance lithium metal battery applications. Full article

(This article belongs to the Special Issue Polymer Surface Modification and Characterization)

► Show Figures

Figure 1

12 pages, 4987 KiB

Open AccessArticle

Printing Formation of Flexible (001)-Oriented PZT Films on Plastic Substrates

by Tomohiko Nakajima and Yuuki Kitanaka

Materials 2023, 16(5), 2116; https://doi.org/10.3390/ma16052116 - 6 Mar 2023

Cited by 1 | Viewed by 1771

Abstract

High-quality, uniaxially oriented, and flexible PbZr_0.52Ti_0.48O₃ (PZT) films were fabricated on flexible RbLaNb₂O₇/BaTiO₃ (RLNO/BTO)-coated polyimide (PI) substrates. All layers were fabricated by a photo-assisted chemical solution deposition (PCSD) process using KrF laser irradiation [...] Read more.

High-quality, uniaxially oriented, and flexible PbZr_0.52Ti_0.48O₃ (PZT) films were fabricated on flexible RbLaNb₂O₇/BaTiO₃ (RLNO/BTO)-coated polyimide (PI) substrates. All layers were fabricated by a photo-assisted chemical solution deposition (PCSD) process using KrF laser irradiation for photocrystallization of the printed precursors. The Dion–Jacobson perovskite RLNO thin films on flexible PI sheets were employed as seed layers for the uniaxially oriented growth of PZT films. To obtain the uniaxially oriented RLNO seed layer, a BTO nanoparticle-dispersion interlayer was fabricated to avoid PI substrate surface damage under excess photothermal heating, and the RLNO has been orientedly grown only at around 40 mJ·cm⁻² at 300 °C. The prepared RLNO seed layer on the BTO/PI substrate showed very high (010)-oriented growth with a very high Lotgering factor (F(010) = 1.0). By using the flexible (010)-oriented RLNO film on BTO/PI, PZT film crystal growth was possible via KrF laser irradiation of a sol–gel-derived precursor film at 50 mJ·cm⁻² at 300 °C. The obtained PZT film showed highly (001)-oriented growth on the flexible plastic substrates with F(001) = 0.92 without any micro-cracks. The RLNO was only uniaxial-oriented grown at the top part of the RLNO amorphous precursor layer. The oriented grown and amorphous phases of RLNO would have two important roles for this multilayered film formation: (1) triggering orientation growth of the PZT film at the top and (2) the stress relaxation of the underneath BTO layer to suppress the micro-crack formation. This is the first time that PZT films have been crystallized directly on flexible substrates. The combined processes of photocrystallization and chemical solution deposition are a cost-effective and highly on-demand process for the fabrication of flexible devices. Full article

(This article belongs to the Special Issue Advances in Flexible Wearable Energy Devices and Systems)

► Show Figures

Figure 1

24 pages, 10553 KiB

Open AccessArticle

Ultrasonic Welding of PEEK Plates with CF Fabric Reinforcement—The Optimization of the Process by Neural Network Simulation

by Vladislav O. Alexenko, Sergey V. Panin, Dmitry Yu. Stepanov, Anton V. Byakov, Alexey A. Bogdanov, Dmitry G. Buslovich, Konstantin S. Panin and Defang Tian

Materials 2023, 16(5), 2115; https://doi.org/10.3390/ma16052115 - 6 Mar 2023

Cited by 8 | Viewed by 2373

Abstract

The optimal mode for ultrasonic welding (USW) of the “PEEK–ED (PEEK)–prepreg (PEI impregnated CF fabric)–ED (PEEK)–PEEK” lap joint was determined by artificial neural network (ANN) simulation, based on the sample of the experimental data expanded with the expert data set. The experimental verification [...] Read more.

The optimal mode for ultrasonic welding (USW) of the “PEEK–ED (PEEK)–prepreg (PEI impregnated CF fabric)–ED (PEEK)–PEEK” lap joint was determined by artificial neural network (ANN) simulation, based on the sample of the experimental data expanded with the expert data set. The experimental verification of the simulation results showed that mode 10 (t = 900 ms, P = 1.7 atm, τ = 2000 ms) ensured the high strength properties and preservation of the structural integrity of the carbon fiber fabric (CFF). Additionally, it showed that the “PEEK–CFF prepreg–PEEK” USW lap joint could be fabricated by the “multi-spot” USW method with the optimal mode 10, which can resist the load per cycle of 50 MPa (the bottom HCF level). The USW mode, determined by ANN simulation for the neat PEEK adherends, did not provide joining both particulate and laminated composite adherends with the CFF prepreg reinforcement. The USW lap joints could be formed when the USW durations (t) were significantly increased up to 1200 and 1600 ms, respectively. In this case, the elastic energy is transferred more efficiently to the welding zone through the upper adherend. Full article

(This article belongs to the Special Issue Advances in the Experimentation and Numerical Modeling of Material Joining Processes)

► Show Figures

Figure 1

24 pages, 16155 KiB

Open AccessArticle

Effect of Er, Si, Hf and Nb Additives on the Thermal Stability of Microstructure, Electrical Resistivity and Microhardness of Fine-Grained Aluminum Alloys of Al-0.25%Zr

by Aleksey V. Nokhrin, Galina S. Nagicheva, Vladimir N. Chuvil’deev, Vladimir I. Kopylov, Aleksandr A. Bobrov and Nataliya Yu. Tabachkova

Materials 2023, 16(5), 2114; https://doi.org/10.3390/ma16052114 - 6 Mar 2023

Cited by 9 | Viewed by 2106

Abstract

The conductor aluminum alloys of Al-0.25wt.%Zr alloyed additionally with X = Er, Si, Hf and Nb were the objects of our investigations. The fine-grained microstructure in the alloys was formed via equal channel angular pressing and rotary swaging. The thermal stability of the [...] Read more.

The conductor aluminum alloys of Al-0.25wt.%Zr alloyed additionally with X = Er, Si, Hf and Nb were the objects of our investigations. The fine-grained microstructure in the alloys was formed via equal channel angular pressing and rotary swaging. The thermal stability of the microstructure, specific electrical resistivity and microhardness of the novel conductor aluminum alloys were investigated. The mechanisms of nucleation of the Al₃(Zr, X) secondary particles during annealing the fine-grained aluminum alloys were determined using the Jones–Mehl–Avrami–Kolmogorov equation. Using the Zener equation, the dependencies of the average secondary particle sizes on the annealing time were obtained on the base of the analysis of the data on the grain growth in the aluminum alloys. The secondary particle nucleation during long-time low-temperature annealing (300 °C, 1000 h) was shown to go preferentially at the cores of the lattice dislocations. The Al-0.25%Zr-0.25%Er-0.20%Hf-0.15%Si alloy subjected to long-time annealing at 300 °C has the optimal combination of microhardness and electrical conductivity (59.8%IACS, Hv = 480 ± 15 MPa). Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

► Show Figures

Figure 1

13 pages, 3949 KiB

Open AccessArticle

Theoretical Study on All-Dielectric Elliptic Cross Metasurface Sensor Governed by Bound States in the Continuum

by Haocheng Cai, Xiaoxu Yu and Luhong Mao

Materials 2023, 16(5), 2113; https://doi.org/10.3390/ma16052113 - 6 Mar 2023

Cited by 2 | Viewed by 2234

Abstract

The appearance of all-dielectric micro–nano photonic devices constructed from high refractive index dielectric materials offers a low-loss platform for the manipulation of electromagnetic waves. The manipulation of electromagnetic waves by all-dielectric metasurfaces reveals unprecedented potential, such as focusing electromagnetic waves and generating structured [...] Read more.

The appearance of all-dielectric micro–nano photonic devices constructed from high refractive index dielectric materials offers a low-loss platform for the manipulation of electromagnetic waves. The manipulation of electromagnetic waves by all-dielectric metasurfaces reveals unprecedented potential, such as focusing electromagnetic waves and generating structured light. Recent advances in dielectric metasurfaces are associated with bound states in the continuum, which can be described as non-radiative eigen modes above the light cone supported by metasurfaces. Here, we propose an all-dielectric metasurface composed of elliptic cross pillars arranged periodically and verify that the displacement distance of a single elliptic pillar can control the strength of the light–matter interaction. Specifically, when the elliptic cross pillar is C₄ symmetric, the quality factor of the metasurface at the Γ point is infinite, also called the bound states in the continuum. Once the C₄ symmetry is broken by moving a single elliptic pillar, the corresponding metasurface engenders mode leakage; however, the large quality factor still exists, which is called the quasi-bound states in the continuum. Then, it is verified by simulation that the designed metasurface is sensitive to the refractive index change of the surrounding medium, indicating that it can be applied for refractive index sensing. Moreover, combined with the specific frequency and the refractive index variation of the medium around the metasurface, the information encryption transmission can be realized effectively. Therefore, we envisage that the designed all-dielectric elliptic cross metasurface can promote the development of miniaturized photon sensors and information encoders due to its sensitivity. Full article

(This article belongs to the Special Issue Advances in Terahertz Metasurfaces)

► Show Figures

Figure 1

19 pages, 10131 KiB

Open AccessArticle

Microstructure, Mechanical Properties and Fracture Behavior of Micron-Sized TiB₂/AlZnMgCu(Sc,Zr) Composites Fabricated by Selective Laser Melting

by Peng Yin, Yantao Liu, Zhuoheng Liang, Wei Pan, Shuobing Shao and Yongzhong Zhang

Materials 2023, 16(5), 2112; https://doi.org/10.3390/ma16052112 - 6 Mar 2023

Cited by 5 | Viewed by 1763

Abstract

In this paper, micron-sized TiB₂/AlZnMgCu(Sc,Zr) composites were fabricated by selective laser melting (SLM) using directly mixed powder. Nearly fully dense (over 99.5%) and crack-free SLM-fabricated TiB₂/AlZnMgCu(Sc,Zr) composite samples were obtained and its microstructure and mechanical properties were investigated. It [...] Read more.

In this paper, micron-sized TiB₂/AlZnMgCu(Sc,Zr) composites were fabricated by selective laser melting (SLM) using directly mixed powder. Nearly fully dense (over 99.5%) and crack-free SLM-fabricated TiB₂/AlZnMgCu(Sc,Zr) composite samples were obtained and its microstructure and mechanical properties were investigated. It is found that the laser absorption rate of powder is improved by introducing micron-sizedTiB₂ particles, then the energy density required for SLM forming can be reduced, and the densification can finally be improved. Some crystalline TiB₂ formed a coherent relationship with the matrix, while some broken TiB₂ particles did not, however, MgZn₂ and Al₃(Sc,Zr) can perform as intermediate phases to connect these non-coherent surfaces to aluminum matrix. All these factors lead to an increase in strength of the composite. The SLM-fabricated micron-sized TiB₂/AlZnMgCu(Sc,Zr) composite finally shows a very high ultimate tensile strength of ~646 MPa and yield strength of ~623 MPa, which are higher than many other aluminum composites fabricated by SLM, while maintaining a relatively good ductility of ~4.5%. The fracture of TiB₂/AlZnMgCu(Sc,Zr) composite is occurred along the TiB₂ particles and the bottom of the molten pool. This is due to the concentration of stress from the sharp tip of TiB₂ particles and the coarse precipitated phase at the bottom of the molten pool. The results show that TiB₂ plays a positive role in AlZnMgCu alloys fabricated by SLM, but finer TiB₂ particles should be studied. Full article

► Show Figures

Figure 1

12 pages, 8663 KiB

Open AccessArticle

Environmental Sustainable Cement Mortars Based on Polyethylene Terephthalate from Recycling Operations

by Francesco Todaro, Andrea Petrella, Giusy Santomasi, Sabino De Gisi and Michele Notarnicola

Materials 2023, 16(5), 2111; https://doi.org/10.3390/ma16052111 - 6 Mar 2023

Cited by 5 | Viewed by 2486

Abstract

The building and construction industry is a key sector behind the ecological transition in that it is one of the main responsible factors in the consumption of natural resources. Thus, in line with circular economy, the use of waste aggregates in mortars is [...] Read more.

The building and construction industry is a key sector behind the ecological transition in that it is one of the main responsible factors in the consumption of natural resources. Thus, in line with circular economy, the use of waste aggregates in mortars is a possible solution to increase the sustainability of cement materials. In the present paper, polyethylene terephthalate (PET) from bottle scraps (without chemical pretreatment) was used as aggregate in cement mortars to replace conventional sand aggregate (20%, 50% and 80% by weight). The fresh and hardened properties of the innovative mixtures proposed were evaluated through a multiscale physical-mechanical investigation. The main results of this study show the feasibility of the reuse of PET waste aggregates as substitutes for natural aggregates in mortars. The mixtures with bare PET resulted in less fluid than the specimens with sand; this was ascribed to the higher volume of the recycled aggregates with respect to sand. Moreover, PET mortars showed a high tensile strength and energy absorption capacity (with Rf = 1.9 ÷ 3.3 MPa, Rc = 6 ÷ 13 MPa); instead, sand samples were characterized by a brittle rupture. The lightweight specimens showed a thermal insulation increase ranging 65–84% with respect to the reference; the best results were obtained with 800 g of PET aggregate, characterized by a decrease in conductivity of approximately 86% concerning the control. The properties of these environmentally sustainable composite materials may be suitable for non-structural insulating artifacts. Full article

(This article belongs to the Special Issue Waste-to-Resource in the Ecological Transition: Opportunities and Challenges)

► Show Figures

Figure 1

29 pages, 7736 KiB

Open AccessReview

Bulk Perovskite Crystal Properties Determined by Heterogeneous Nucleation and Growth

by Pranta Barua and Inchan Hwang

Materials 2023, 16(5), 2110; https://doi.org/10.3390/ma16052110 - 5 Mar 2023

Cited by 12 | Viewed by 6681

Abstract

In metal halide perovskites, charge transport in the bulk of the films is influenced by trapping and release and nonradiative recombination at ionic and crystal defects. Thus, mitigating the formation of defects during the synthesis process of perovskites from precursors is required for [...] Read more.

In metal halide perovskites, charge transport in the bulk of the films is influenced by trapping and release and nonradiative recombination at ionic and crystal defects. Thus, mitigating the formation of defects during the synthesis process of perovskites from precursors is required for better device performance. An in-depth understanding of the nucleation and growth mechanisms of perovskite layers is crucial for the successful solution processing of organic–inorganic perovskite thin films for optoelectronic applications. In particular, heterogeneous nucleation, which occurs at the interface, must be understood in detail, as it has an effect on the bulk properties of perovskites. This review presents a detailed discussion on the controlled nucleation and growth kinetics of interfacial perovskite crystal growth. Heterogeneous nucleation kinetics can be controlled by modifying the perovskite solution and the interfacial properties of perovskites adjacent to the underlaying layer and to the air interface. As factors influencing the nucleation kinetics, the effects of surface energy, interfacial engineering, polymer additives, solution concentration, antisolvents, and temperature are discussed. The importance of the nucleation and crystal growth of single-crystal, nanocrystal, and quasi-two-dimensional perovskites is also discussed with respect to the crystallographic orientation. Full article

(This article belongs to the Special Issue Charge Transport in Perovskite Solar Cells: Materials and Mechanisms)

► Show Figures

Figure 1

15 pages, 10255 KiB

Open AccessArticle

Experimental Research and Numerical Simulation of Laser Welding of 303Cu/440C-Nb Stainless-Steel Thin-Walled Natural-Gas Injector for Vehicles

by Lisen Zhou, Dongya Li, Chonghai Xu, Zhaoxing Zheng and Yu Liu

Materials 2023, 16(5), 2109; https://doi.org/10.3390/ma16052109 - 5 Mar 2023

Cited by 1 | Viewed by 2446

Abstract

This paper presents the results of research on laser lap welding technology of heterogeneous materials and a laser post-heat treatment method to enhance welding performance. The purpose of this study is to reveal the welding principle of austenitic/martensitic dissimilar stainless-steel materials (3030Cu/440C-Nb) and [...] Read more.

This paper presents the results of research on laser lap welding technology of heterogeneous materials and a laser post-heat treatment method to enhance welding performance. The purpose of this study is to reveal the welding principle of austenitic/martensitic dissimilar stainless-steel materials (3030Cu/440C-Nb) and to further obtain welded joints with good mechanical and sealing properties. A natural-gas injector valve is taken as the study case where its valve pipe (303Cu) and valve seat (440C-Nb) are welded. Experiments and numerical simulations were conducted where the welded joints’ temperature and stress fields, microstructure, element distribution, and microhardness were studied. The results showed that the residual equivalent stresses and uneven fusion zone tend to concentrate at the joint of two materials within the welded joint. The hardness of the 303Cu side (181.8 HV) is less than the 440C-Nb side (266 HV) in the center of the welded joint. The laser post-heat treatment can reduce the residual equivalent stress in the welded joint and improve the mechanical and sealing properties. The results of the press-off force test and the helium leakage test showed that the press-off force increased from 9640 N to 10,046 N and the helium leakage rate decreased from 3.34 × 10⁻⁴ to 3.96 × 10⁻⁶. Full article

(This article belongs to the Topic Laser Welding of Metallic Materials)

► Show Figures

Figure 1

14 pages, 4881 KiB

Open AccessEditor’s ChoiceArticle

Inductive Determination of Rate-Reaction Equation Parameters for Dislocation Structure Formation Using Artificial Neural Network

by Yoshitaka Umeno, Emi Kawai, Atsushi Kubo, Hiroyuki Shima and Takashi Sumigawa

Materials 2023, 16(5), 2108; https://doi.org/10.3390/ma16052108 - 5 Mar 2023

Cited by 6 | Viewed by 1678

Abstract

The reaction–diffusion equation approach, which solves differential equations of the development of density distributions of mobile and immobile dislocations under mutual interactions, is a method widely used to model the dislocation structure formation. A challenge in the approach is the difficulty in the [...] Read more.

The reaction–diffusion equation approach, which solves differential equations of the development of density distributions of mobile and immobile dislocations under mutual interactions, is a method widely used to model the dislocation structure formation. A challenge in the approach is the difficulty in the determination of appropriate parameters in the governing equations because deductive (bottom-up) determination for such a phenomenological model is problematic. To circumvent this problem, we propose an inductive approach utilizing the machine-learning method to search a parameter set that produces simulation results consistent with experiments. Using a thin film model, we performed numerical simulations based on the reaction–diffusion equations for various sets of input parameters to obtain dislocation patterns. The resulting patterns are represented by the following two parameters; the number of dislocation walls (

p_{2}

), and the average width of the walls (

p_{3}

). Then, we constructed an artificial neural network (ANN) model to map between the input parameters and the output dislocation patterns. The constructed ANN model was found to be able to predict dislocation patterns; i.e., average errors in

p_{2}

and

p_{3}

for test data having 10% deviation from the training data were within 7% of the average magnitude of

p_{2}

and

p_{3}

. The proposed scheme enables us to find appropriate constitutive laws that lead to reasonable simulation results, once realistic observations of the phenomenon in question are provided. This approach provides a new scheme to bridge models for different length scales in the hierarchical multiscale simulation framework. Full article

(This article belongs to the Section Materials Simulation and Design)

► Show Figures

Figure 1

17 pages, 4087 KiB

Open AccessArticle

Evaluation of Mechanical Properties of Glass Ionomer Cements Reinforced with Synthesized Diopside Produced via Sol–Gel Method

by Ali Maleki Nojehdehi, Farina Moghaddam and Bejan Hamawandi

Materials 2023, 16(5), 2107; https://doi.org/10.3390/ma16052107 - 5 Mar 2023

Cited by 2 | Viewed by 2316

Abstract

This study aimed to fabricate a glass ionomer cement/diopside (GIC/DIO) nanocomposite to improve its mechanical properties for biomaterials applications. For this purpose, diopside was synthesized using a sol–gel method. Then, for preparing the nanocomposite, 2, 4, and 6 wt% diopside were added to [...] Read more.

This study aimed to fabricate a glass ionomer cement/diopside (GIC/DIO) nanocomposite to improve its mechanical properties for biomaterials applications. For this purpose, diopside was synthesized using a sol–gel method. Then, for preparing the nanocomposite, 2, 4, and 6 wt% diopside were added to a glass ionomer cement (GIC). Subsequently, X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), and Fourier transform infrared spectrophotometry (FTIR) analyses were used to characterize the synthesized diopside. Furthermore, the compressive strength, microhardness, and fracture toughness of the fabricated nanocomposite were evaluated, and a fluoride-releasing test in artificial saliva was also applied. The highest concurrent enhancements of compressive strength (1155.7 MPa), microhardness (148 HV), and fracture toughness (5.189 MPa·m^1/2) were observed for the glass ionomer cement (GIC) with 4 wt% diopside nanocomposite. In addition, the results of the fluoride-releasing test showed that the amount of released fluoride from the prepared nanocomposite was slightly lower than the glass ionomer cement (GIC). Overall, the improvement in mechanical properties and optimal fluoride release of prepared nanocomposites can introduce suitable options for dental restorations under load and orthopedic implants. Full article

(This article belongs to the Special Issue Advanced Biomaterials in Dentistry and Healthcare)

► Show Figures

Figure 1

18 pages, 6456 KiB

Open AccessReview

Supported Ionic Liquid Phase Catalysts Dedicated for Continuous Flow Synthesis

by Piotr Latos, Anna Wolny and Anna Chrobok

Materials 2023, 16(5), 2106; https://doi.org/10.3390/ma16052106 - 5 Mar 2023

Cited by 12 | Viewed by 3623

Abstract

Heterogeneous catalysis, although known for over a century, is constantly improved and plays a key role in solving the present problems in chemical technology. Thanks to the development of modern materials engineering, solid supports for catalytic phases having a highly developed surface are [...] Read more.

Heterogeneous catalysis, although known for over a century, is constantly improved and plays a key role in solving the present problems in chemical technology. Thanks to the development of modern materials engineering, solid supports for catalytic phases having a highly developed surface are available. Recently, continuous-flow synthesis started to be a key technology in the synthesis of high added value chemicals. These processes are more efficient, sustainable, safer and cheaper to operate. The most promising is the use of heterogeneous catalyst with column-type fixed-bed reactors. The advantages of the use of heterogeneous catalyst in continuous flow reactors are the physical separation of product and catalyst, as well as the reduction in inactivation and loss of the catalyst. However, the state-of-the-art use of heterogeneous catalysts in flow systems compared to homogenous ones remains still open. The lifetime of heterogeneous catalysts remains a significant hurdle to realise sustainable flow synthesis. The goal of this review article was to present a state of knowledge concerning the application of Supported Ionic Liquid Phase (SILP) catalysts dedicated for continuous flow synthesis. Full article

(This article belongs to the Collection Catalysts: Preparation, Catalytic Performance and Catalytic Reaction)

► Show Figures

Figure 1

16 pages, 4880 KiB

Open AccessArticle

Hybrid Fluoro-Based Polymers/Graphite Foil for H₂/Natural Gas Separation

by Angela Malara, Lucio Bonaccorsi, Antonio Fotia, Pier Luigi Antonucci and Patrizia Frontera

Materials 2023, 16(5), 2105; https://doi.org/10.3390/ma16052105 - 5 Mar 2023

Cited by 3 | Viewed by 1657

Abstract

Membrane technologies and materials development appear crucial for the hydrogen/natural gas separation in the impending transition to the hydrogen economy. Transporting hydrogen through the existing natural gas network could result less expensive than a brand-new pipe system. Currently, many studies are focused on [...] Read more.

Membrane technologies and materials development appear crucial for the hydrogen/natural gas separation in the impending transition to the hydrogen economy. Transporting hydrogen through the existing natural gas network could result less expensive than a brand-new pipe system. Currently, many studies are focused on the development of novel structured materials for gas separation applications, including the combination of various kind of additives in polymeric matrix. Numerous gas pairs have been investigated and the gas transport mechanism in those membranes has been elucidated. However, the selective separation of high purity hydrogen from hydrogen/methane mixtures is still a big challenge and nowadays needs a great improvement to promote the transition towards more sustainable energy source. In this context, because of their remarkable properties, fluoro-based polymers, such as PVDF-HFP and Nafion^TM, are among the most popular membrane materials, even if a further optimization is needed. In this study, hybrid polymer-based membranes were deposited as thin films on large graphite surfaces. Different weight ratios of PVDF-HFP and Nafion^TM polymers supported over 200 μm thick graphite foils were tested toward hydrogen/methane gas mixture separation. Small punch tests were carried out to study the membrane mechanical behaviour, reproducing the testing conditions. Finally, the permeability and the gas separation activity of hydrogen/methane over membranes were investigated at room temperature (25 °C) and near atmospheric pressure (using a pressure difference of 1.5 bar). The best performance of the developed membranes was registered when the 4:1 polymer PVDF-HFP/Nafion^TM weight ratio was used. In particular, starting from the 1:1 hydrogen/methane gas mixture, a 32.6% (v%) H₂ enrichment was measured. Furthermore, there was a good agreement between the experimental and theoretical selectivity values. Full article

(This article belongs to the Special Issue Advances in Materials Science for Engineering Applications)

► Show Figures

Figure 1

15 pages, 8506 KiB

Open AccessArticle

Reduced Slit Rolling Power in Rebar Steel Production

by Rashid Khan, Sabbah Ataya, Islam Elgammal and Khamis Essa

Materials 2023, 16(5), 2104; https://doi.org/10.3390/ma16052104 - 5 Mar 2023

Viewed by 3179

Abstract

The rolling process of rebar steel production is one of the well established manufacturing processes; however, it should be subjected to revision and redesign for productivity enhancement and power reduction throughout the slit rolling process. In this work, slitting passes are extensively reviewed [...] Read more.

The rolling process of rebar steel production is one of the well established manufacturing processes; however, it should be subjected to revision and redesign for productivity enhancement and power reduction throughout the slit rolling process. In this work, slitting passes are extensively reviewed and modified for the attainment of better rolling stability and reduction in power consumption. The study has been applied for grade B400B-R Egyptian rebar steel, which is equivalent to steel grade ASTM A615M, Grade 40. Traditionally, the rolled strip in the rolling pass is edged before implementing a slitting pass using grooved rolls; this produces a single barreled strip. This single barrel form causes instability in the next slitting stand on the pressing by the slitting roll knife. Multiple industrial trials are attempted to achieve the deformation of the edging stand using a grooveless roll. As a result, a double barreled slab is produced. In parallel, finite element simulations of the edging pass are performed using grooved and grooveless rolls, and similar slab geometry with single and double barreled form are produced. In addition, further finite element simulations of the slitting stand are execute using idealized single barreled strips. The power calculated by the FE simulations of the single barreled strip is (245 kW), which is in acceptable agreement with the experimental observations in the industrial process (216 kW). This result validates the FE modeling parameters such as material model and boundary conditions. The FE modeling is extended to the slit rolling stand of a double barreled strip, which was previously produced by the grooveless edging rolls. It is found that the power consumption is (165 kW) 12% lower than the power consumed (185 kW) for slitting the single barreled strip. Full article

(This article belongs to the Special Issue Advancements in Performance of Steel and Metallic Materials in Civil Infrastructure)

► Show Figures

Figure 1

18 pages, 17293 KiB

Open AccessArticle

Development of Preliminary Precision Forging Technology and Concept for Tools Used to Reforge 60E1A6 Profile Needle Rails with the Use of Numerical and Physical Modeling

by Marek Hawryluk, Piotr Cygan, Jakub Krawczyk, Artur Barełkowski, Jacek Ziemba, Filip Lewandowski and Igor Wieczorek

Materials 2023, 16(5), 2103; https://doi.org/10.3390/ma16052103 - 5 Mar 2023

Cited by 1 | Viewed by 2088

Abstract

This study examines the possibilities of applying numerical and physical modeling to the elaboration of technology and design of tools used in the hot forging of needle rails for railroad turnouts. First, a numerical model of a three-stage process for forging a needle [...] Read more.

This study examines the possibilities of applying numerical and physical modeling to the elaboration of technology and design of tools used in the hot forging of needle rails for railroad turnouts. First, a numerical model of a three-stage process for forging a needle from lead was built in order to develop a proper geometry of the tools’ working impressions for physical modeling. Based on preliminary results of the force parameters, a decision was made to verify the numerical modeling at 1:4 scale due to forging force values as well as agreement of the numerical and physical modeling results, which was confirmed by the similar courses of forging forces and a comparison of the 3D scan image of the forged lead rail with the CAD model obtained from FEM. The final stage of our research was modeling an industrial forging process in order to determine the preliminary assumptions of this newly developed method of precision forging using a hydraulic press as well as preparing tools to reforge a needle rail from the target material, i.e., 350HT steel with a 60E1A6 profile to the 60E1 profile used in railroad turnouts. Full article

(This article belongs to the Special Issue Advances in Metal Cutting, Casting, Forming and Heat Treatment)

► Show Figures

Figure 1

21 pages, 7531 KiB

Open AccessArticle

Residual Stress Distribution in a Copper-Aluminum Multifilament Composite Fabricated by Rotary Swaging

by David Canelo-Yubero, Radim Kocich, Jan Šaroun and Pavel Strunz

Materials 2023, 16(5), 2102; https://doi.org/10.3390/ma16052102 - 5 Mar 2023

Cited by 4 | Viewed by 1890

Abstract

Rotary swaging is a promising technique for the fabrication of clad Cu/Al composites. Residual stresses appearing during the processing of a special arrangement of Al filaments within the Cu matrix and the influence of the bar reversal between the passes were studied by [...] Read more.

Rotary swaging is a promising technique for the fabrication of clad Cu/Al composites. Residual stresses appearing during the processing of a special arrangement of Al filaments within the Cu matrix and the influence of the bar reversal between the passes were studied by (i) neutron diffraction using a novel evaluation procedure for pseudo-strain correction and (ii) a finite element method simulation. The initial study of the stress differences in the Cu phase allowed us to infer that the stresses around the central Al filament are hydrostatic when the sample is reversed during the passes. This fact enabled the calculation of the stress-free reference and, consequently, the analysis of the hydrostatic and deviatoric components. Finally, the stresses with the von Mises relation were calculated. Hydrostatic stresses (far from the filaments) and axial deviatoric stresses are zero or compressive for both reversed and non-reversed samples. The reversal of the bar direction slightly changes the overall state within the region of high density of Al filaments, where hydrostatic stresses tend to be tensile, but it seems to be advantageous for avoiding plastification in the regions without Al wires. The finite element analysis revealed the presence of shear stresses; nevertheless, stresses calculated with the von Mises relation show similar trends in the simulation and in the neutron measurements. Microstresses are suggested as a possible reason for the large width of the neutron diffraction peak in the measurement of the radial direction. Full article

(This article belongs to the Special Issue Structural Phenomena in Metallic Materials for Demanding Applications)

► Show Figures

Figure 1

24 pages, 4105 KiB

Open AccessArticle

Hierarchical Biobased Macroporous/Mesoporous Carbon: Fabrication, Characterization and Electrochemical/Ion Exchange Properties

by Mariano M. Bruno, N. Gustavo Cotella and Cesar A. Barbero

Materials 2023, 16(5), 2101; https://doi.org/10.3390/ma16052101 - 5 Mar 2023

Viewed by 1916

Abstract

With the goal of improving the mechanical properties of porous hierarchical carbon, cellulosic fiber fabric was incorporated into the resorcinol/formaldehyde (RF) precursor resins. The composites were carbonized in an inert atmosphere, and the carbonization process was monitored by TGA/MS. The mechanical properties, evaluated [...] Read more.

With the goal of improving the mechanical properties of porous hierarchical carbon, cellulosic fiber fabric was incorporated into the resorcinol/formaldehyde (RF) precursor resins. The composites were carbonized in an inert atmosphere, and the carbonization process was monitored by TGA/MS. The mechanical properties, evaluated by nanoindentation, show an increase in the elastic modulus due to the reinforcing effect of the carbonized fiber fabric. It was found that the adsorption of the RF resin precursor onto the fabric stabilizes its porosity (micro and mesopores) during drying while incorporating macropores. The textural properties are evaluated by N₂ adsorption isotherm, which shows a surface area (BET) of 558 m²g⁻¹. The electrochemical properties of the porous carbon are evaluated by cyclic voltammetry (CV), chronocoulometry (CC), and electrochemical impedance spectroscopy (EIS). Specific capacitances (in 1 M H₂SO₄) of up to 182 Fg⁻¹ (CV) and 160 Fg⁻¹ (EIS) are measured. The potential-driven ion exchange was evaluated using Probe Bean Deflection techniques. It is observed that ions (protons) are expulsed upon oxidation in acid media by the oxidation of hydroquinone moieties present on the carbon surface. In neutral media, when the potential is varied from values negative to positive of the potential of zero charge, cation release, followed by anion insertion, is found. Full article

(This article belongs to the Special Issue Current and Future Trends in Carbon-Based Materials)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Materials, Volume 16, Issue 5 (March-1 2023) – 375 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI