Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
5.8
3.1
Journals
Materials
Editor’s Choice
materials-logo

Journal Menu

► Journal Menu

Journal Browser

► Journal Browser
share announcement

Editor’s Choice Articles

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

Order results
Result details
Results per page
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
14 pages, 2906 KiB  
Article
First-Principles Study of Adsorption of CH4 on a Fluorinated Model NiF2 Surface
by Tilen Lindič and Beate Paulus
Materials 2024, 17(9), 2062; https://doi.org/10.3390/ma17092062 - 27 Apr 2024
Viewed by 756
Abstract
Electrochemical fluorination on nickel anodes, also known as the Simons’ process, is an important fluorination method used on an industrial scale. Despite its success, the mechanism is still under debate. One of the proposed mechanisms involves higher valent nickel species formed on an [...] Read more.
Electrochemical fluorination on nickel anodes, also known as the Simons’ process, is an important fluorination method used on an industrial scale. Despite its success, the mechanism is still under debate. One of the proposed mechanisms involves higher valent nickel species formed on an anode acting as effective fluorinating agents. Here we report the first attempt to study fluorination by means of first principles investigation. We have identified a possible surface model from the simplest binary nickel fluoride (NiF2). A twice oxidized NiF2(F2) (001) surface exhibits higher valent nickel centers and a fluorination source that can be best characterized as an [F2]− like unit, readily available to aid fluorination. We have studied the adsorption of CH4 and the co-adsorption of CH4 and HF on this surface by means of periodic density functional theory. By the adsorption of CH4, we found two main outcomes on the surface. Unreactive physisorption of CH4 and dissociative chemisorption resulting in the formation of CH3F and HF. The co-adsorption with the HF gave rise to four main outcomes, namely the formation of CH3F, CH2F2, CH3 radical, and also physisorbed CH4. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Catalytic Materials)
►▼ Show Figures

Figure 1

18 pages, 6871 KiB  
Article
The Use of Wind Turbine Blades to Build Road Noise Barriers as an Example of a Circular Economy Model
by Mirosław Broniewicz, Anna Halicka, Lidia Buda-Ożóg, Filip Broniewicz, Damian Nykiel and Łukasz Jabłoński
Materials 2024, 17(9), 2048; https://doi.org/10.3390/ma17092048 - 26 Apr 2024
Viewed by 602
Abstract
This project’s objective was to create a circular economy in the composites sector by examining the possibility of using wind turbine blade composite materials to construct noise-absorbing barriers for roads. The possibility of constructing road noise barrier panels from components obtained from turbine [...] Read more.
This project’s objective was to create a circular economy in the composites sector by examining the possibility of using wind turbine blade composite materials to construct noise-absorbing barriers for roads. The possibility of constructing road noise barrier panels from components obtained from turbine blades was conceptually examined, and the geometry and construction of wind turbine blades were evaluated for their suitability as filler components for panels. The tensile strength parameters of two types of composites made from windmill blades—a solid composite and a sandwich type—were established based on material tests. The strength of the composite elements cut from a windmill propeller was analyzed, and a three-dimensional numerical model was created using the finite element method. The strength values of the composite used to construct the noise barriers were compared with the stresses resulting from loads operating on the road noise barriers, as determined in compliance with current standards. It was discovered that acoustic screens composed of composite materials derived from wind turbine blades may withstand loads associated with wind pressure and vehicle traffic with sufficient resistance. In order to evaluate the environmental benefits resulting from the use of composite material made from wind turbine blades to make noise barriers, this study presents the values of the embodied energy and embodied carbon for several types of road noise barriers using life cycle assessment. Full article
(This article belongs to the Special Issue Manufacturing of Porous Acoustic Structures and Metamaterials)
►▼ Show Figures

Figure 1

21 pages, 11311 KiB  
Article
Investigating the Impact Behavior of Carbon Fiber/Polymethacrylimide (PMI) Foam Sandwich Composites for Personal Protective Equipment
by Xinyu Zhang, Miao Tian, Jun Li and Xinggang Chen
Materials 2024, 17(7), 1683; https://doi.org/10.3390/ma17071683 - 6 Apr 2024
Viewed by 921
Abstract
To improve the shock resistance of personal protective equipment and reduce casualties due to shock wave accidents, this study prepared four types of carbon fiber/polymethacrylimide (PMI) foam sandwich panels with different face/back layer thicknesses and core layer densities and subjected them to quasi-static [...] Read more.
To improve the shock resistance of personal protective equipment and reduce casualties due to shock wave accidents, this study prepared four types of carbon fiber/polymethacrylimide (PMI) foam sandwich panels with different face/back layer thicknesses and core layer densities and subjected them to quasi-static compression, low-speed impact, high-speed impact, and non-destructive tests. The mechanical properties and energy absorption capacities of the impact-resistant panels, featuring ceramic/ultra-high molecular-weight polyethylene (UHMWPE) and carbon fiber/PMI foam structures, were evaluated and compared, and the feasibility of using the latter as a raw material for personal impact-resistant equipment was also evaluated. For the PMI sandwich panel with a constant total thickness, increasing the core layer density and face/back layer thickness enhanced the energy absorption capacity, and increased the peak stress of the face layer. Under a constant strain, the energy absorption value of all specimens increased with increasing impact speed. When a 10 kg hammer impacted the specimen surface at a speed of 1.5 m/s, the foam sandwich panels retained better integrity than the ceramic/UHMWPE panel. The results showed that the carbon fiber/PMI foam sandwich panels were suitable for applications that require the flexible movement of the wearer under shock waves, and provide an experimental basis for designing impact-resistant equipment with low weight, high strength, and high energy absorption capacities. Full article
(This article belongs to the Special Issue Recent Progress in Functional Materials and Their Applications)
►▼ Show Figures

Figure 1

7 pages, 1884 KiB  
Communication
Three-Dimensional Epitaxy of Low-Defect 3C-SiC on a Geometrically Modified Silicon Substrate
by Gerard Colston, Kelly Turner, Arne Renz, Kushani Perera, Peter M. Gammon, Marina Antoniou and Vishal A. Shah
Materials 2024, 17(7), 1587; https://doi.org/10.3390/ma17071587 - 30 Mar 2024
Viewed by 723
Abstract
We demonstrate the growth of 3C-SiC with reduced planar defects on a micro-scale compliant substrate. Heteroepitaxial growth of 3C-SiC on trenches with a width and separation of 2 µm, etched into a Si(001) substrate, is found to suppress defect propagation through the epilayer. [...] Read more.
We demonstrate the growth of 3C-SiC with reduced planar defects on a micro-scale compliant substrate. Heteroepitaxial growth of 3C-SiC on trenches with a width and separation of 2 µm, etched into a Si(001) substrate, is found to suppress defect propagation through the epilayer. Stacking faults and other planar defects are channeled away from the center of the patterned structures, which are rounded through the use of H2 annealing at 1100 °C. Void formation between the columns of 3C-SiC growth acts as a termination point for defects, and coalescence of these columns into a continuous epilayer is promoted through the addition of HCl in the growth phase. The process of fabricating these compliant substrates utilizes standard processing techniques found within the semiconductor industry and is independent of the substrate orientation and offcut. Full article
(This article belongs to the Special Issue Feature Papers in Electronic Materials Section (Volume 2)—15th Anniversary of Materials)
►▼ Show Figures

Figure 1

15 pages, 6948 KiB  
Article
Enhancement of Strength–Ductility Synergy of Al-Li Cast Alloy via New Forming Processes and Sc Addition
by Shulin Lü, Zhaoxiang Yan, Yu Pan, Jianyu Li, Shusen Wu and Wei Guo
Materials 2024, 17(7), 1558; https://doi.org/10.3390/ma17071558 - 28 Mar 2024
Viewed by 767
Abstract
In this study, concurrent enhancements in both strength and ductility of the Al-2Li-2Cu-0.5Mg-0.2Zr cast alloy (hereafter referred to as Al-Li) were achieved through an optimized forming process comprising ultrasonic treatment followed by squeeze casting, coupled with the incorporation of Sc. Initially, the variations [...] Read more.
In this study, concurrent enhancements in both strength and ductility of the Al-2Li-2Cu-0.5Mg-0.2Zr cast alloy (hereafter referred to as Al-Li) were achieved through an optimized forming process comprising ultrasonic treatment followed by squeeze casting, coupled with the incorporation of Sc. Initially, the variations in the microstructure and mechanical properties of the Sc-free Al-Li cast alloy (i.e., alloy A) during various forming processes were investigated. The results revealed that the grain size in the UT+SC (ultrasonic treatment + squeeze casting) alloy was reduced by 76.3% and 57.7%, respectively, compared to those of the GC (gravity casting) or SC alloys. Additionally, significant improvements were observed in its compositional segregation and porosity reduction. After UT+SC, the ultimate tensile strength (UTS), yield strength (YS), and elongation reached 235 MPa, 135 MPa, and 15%, respectively, which were 113.6%, 28.6%, and 1150% higher than those of the GC alloy. Subsequently, the Al-Li cast alloy containing 0.2 wt.% Sc (referred to as alloy B) exhibited even finer grains under the UT+SC process, resulting in simultaneous enhancements in its UTS, YS, and elongation. Interestingly, the product of ultimate tensile strength and elongation (i.e., UTS × EL) for both alloys reached 36 GPa•% and 42 GPa•%, respectively, which is much higher than that of other Al-Li cast alloys reported in the available literature. Full article
(This article belongs to the Special Issue Microstructure Engineering of Metals and Alloys, Volume II)
►▼ Show Figures

Figure 1

26 pages, 8501 KiB  
Article
Process–Structure–Property Relationship Development in Large-Format Additive Manufacturing: Fiber Alignment and Ultimate Tensile Strength
by Lucinda K. Slattery, Zackery B. McClelland and Samuel T. Hess
Materials 2024, 17(7), 1526; https://doi.org/10.3390/ma17071526 - 27 Mar 2024
Viewed by 856
Abstract
Parts made through additive manufacturing (AM) often exhibit mechanical anisotropy due to the time-based deposition of material and processing parameters. In polymer material extrusion (MEX), printed parts have weak points at layer interfaces, perpendicular to the direction of deposition. Poly(lactic acid) with chopped [...] Read more.
Parts made through additive manufacturing (AM) often exhibit mechanical anisotropy due to the time-based deposition of material and processing parameters. In polymer material extrusion (MEX), printed parts have weak points at layer interfaces, perpendicular to the direction of deposition. Poly(lactic acid) with chopped carbon fiber was printed on a large-format pellet printer at various extrusion rates with the same tool pathing to measure the fiber alignment with deposition via two methods and relate it to the ultimate tensile strength (UTS). Within a singular printed bead, an X-ray microscopy (XRM) scan was conducted to produce a reconstruction of the internal microstructure and 3D object data on the length and orientation of fibers. From the scan, discrete images were used in an image analysis technique to determine the fiber alignment to deposition without 3D object data on each fiber’s size. Both the object method and the discrete image method showed a negative relationship between the extrusion rate and fiber alignment, with −34.64% and −53.43% alignment per extrusion multiplier, respectively, as the slopes of the linear regression. Tensile testing was conducted to determine the correlation between the fiber alignment and UTS. For all extrusion rates tested, as the extrusion multiplier increased, the percent difference in the UTS decreased, to a minimum of 8.12 ± 14.40%. The use of image analysis for the determination of the fiber alignment provides a possible method for relating the microstructure to the meso-property of AM parts, and the relationship between the microstructure and the properties establishes process–structure–property relationships for large-format AM. Full article
(This article belongs to the Special Issue Additive Manufacturing of Polymer-Fiber Composites)
►▼ Show Figures

Figure 1

15 pages, 6758 KiB  
Article
Modeling of Charge-to-Breakdown with an Electron Trapping Model for Analysis of Thermal Gate Oxide Failure Mechanism in SiC Power MOSFETs
by Jiashu Qian, Limeng Shi, Michael Jin, Monikuntala Bhattacharya, Atsushi Shimbori, Hengyu Yu, Shiva Houshmand, Marvin H. White and Anant K. Agarwal
Materials 2024, 17(7), 1455; https://doi.org/10.3390/ma17071455 - 22 Mar 2024
Viewed by 916
Abstract
The failure mechanism of thermal gate oxide in silicon carbide (SiC) power metal oxide semiconductor field effect transistors (MOSFETs), whether it is field-driven breakdown or charge-driven breakdown, has always been a controversial topic. Previous studies have demonstrated that the failure time of thermally [...] Read more.
The failure mechanism of thermal gate oxide in silicon carbide (SiC) power metal oxide semiconductor field effect transistors (MOSFETs), whether it is field-driven breakdown or charge-driven breakdown, has always been a controversial topic. Previous studies have demonstrated that the failure time of thermally grown silicon dioxide (SiO2) on SiC stressed with a constant voltage is indicated as charge driven rather than field driven through the observation of Weibull Slope β. Considering the importance of the accurate failure mechanism for the thermal gate oxide lifetime prediction model of time-dependent dielectric breakdown (TDDB), charge-driven breakdown needs to be further fundamentally justified. In this work, the charge-to-breakdown (QBD) of the thermal gate oxide in a type of commercial planar SiC power MOSFETs, under the constant current stress (CCS), constant voltage stress (CVS), and pulsed voltage stress (PVS) are extracted, respectively. A mathematical electron trapping model in thermal SiO2 grown on single crystal silicon (Si) under CCS, which was proposed by M. Liang et al., is proven to work equally well with thermal SiO2 grown on SiC and used to deduce the QBD model of the device under test (DUT). Compared with the QBD obtained under the three stress conditions, the charge-driven breakdown mechanism is validated in the thermal gate oxide of SiC power MOSFETs. Full article
(This article belongs to the Special Issue Silicon Carbide: Material Growth, Device Processing and Applications)
►▼ Show Figures

Figure 1

14 pages, 6419 KiB  
Article
Tailoring Iridium Valence States on ZSM-5 for Enhanced Catalytic Performance in CO Selective Catalytic Reduction of NO under Oxygen-Enriched Environments
by Yarong Bai, Chuhan Miao, Weilong Ouyang, Lang Wang, Haiqiang Wang and Zhongbiao Wu
Materials 2024, 17(6), 1440; https://doi.org/10.3390/ma17061440 - 21 Mar 2024
Viewed by 728
Abstract
Barium and iridium supported on Zeolite Socony Mobil-5 (ZSM-5) are efficient catalysts for the selective catalytic reduction of nitric oxide by carbon monoxide (CO-SCR), with enhanced cyclic stability. The introduction of Ba hindered the oxidation of metallic Ir active species and enabled Ir [...] Read more.
Barium and iridium supported on Zeolite Socony Mobil-5 (ZSM-5) are efficient catalysts for the selective catalytic reduction of nitric oxide by carbon monoxide (CO-SCR), with enhanced cyclic stability. The introduction of Ba hindered the oxidation of metallic Ir active species and enabled Ir to maintain an active metallic state, thereby preventing a decrease in catalytic activity in the CO-SCR reaction. Moreover, the Ba modification increased the NO adsorption of the catalyst, further improving the catalytic activity. Owing to the better anti-oxidation ability of Ir0 in IrBa0.2/ZSM-5(27) than in Ir/ZSM-5(27), IrBa0.2/ZSM-5(27) showed better stability than Ir/ZSM-5(27). Considering that all samples in the present study were tested to simulate actual flue gases (such as sintering flue gas and coke oven flue gas), NH3 was introduced into the reaction system to serve as an extra reductant for NOx. The NOx conversion to N2 (77.1%) was substantially improved using the NH3-CO-SCR system. The proposed catalysts and reaction systems are promising alternatives for treating flue gas, which contains considerable amounts of NOx and CO in oxygen-enriched environments. Full article
(This article belongs to the Section Catalytic Materials)
►▼ Show Figures

Figure 1

12 pages, 8092 KiB  
Article
A Study of the Adsorption Properties of Individual Atoms on the Graphene Surface: Density Functional Theory Calculations Assisted by Machine Learning Techniques
by Jingtao Huang, Mo Chen, Jingteng Xue, Mingwei Li, Yuan Cheng, Zhonghong Lai, Jin Hu, Fei Zhou, Nan Qu, Yong Liu and Jingchuan Zhu
Materials 2024, 17(6), 1428; https://doi.org/10.3390/ma17061428 - 20 Mar 2024
Viewed by 815
Abstract
In this research, the adsorption performance of individual atoms on the surface of monolayer graphene surface was systematically investigated using machine learning methods to accelerate density functional theory. The adsorption behaviors of over thirty different atoms on the graphene surface were computationally analyzed. [...] Read more.
In this research, the adsorption performance of individual atoms on the surface of monolayer graphene surface was systematically investigated using machine learning methods to accelerate density functional theory. The adsorption behaviors of over thirty different atoms on the graphene surface were computationally analyzed. The adsorption energy and distance were extracted as the research targets, and the basic information of atoms (such as atomic radius, ionic radius, etc.) were used as the feature values to establish the dataset. Through feature engineering selection, the corresponding input feature values for the input-output relationship were determined. By comparing different models on the dataset using five-fold cross-validation, the mathematical model that best fits the dataset was identified. The optimal model was further fine-tuned by adjusting of the best mathematical ML model. Subsequently, we verified the accuracy of the established machine learning model. Finally, the precision of the machine learning model forecasts was verified by the method of comparing and contrasting machine learning results with density functional theory. The results suggest that elements such as Zr, Ti, Sc, and Si possess some potential in controlling the interfacial reaction of graphene/aluminum composites. By using machine learning to accelerate first-principles calculations, we have further expanded our choice of research methods and accelerated the pace of studying element–graphene interactions. Full article
(This article belongs to the Special Issue Adsorption Materials and Their Applications)
►▼ Show Figures

Figure 1

23 pages, 30993 KiB  
Article
Numerical Simulation and Machine Learning Prediction of the Direct Chill Casting Process of Large-Scale Aluminum Ingots
by Guanhua Guo, Ting Yao, Wensheng Liu, Sai Tang, Daihong Xiao, Lanping Huang, Lei Wu, Zhaohui Feng and Xiaobing Gao
Materials 2024, 17(6), 1409; https://doi.org/10.3390/ma17061409 - 19 Mar 2024
Viewed by 1057
Abstract
The large-scale ingot of the 7xxx-series aluminum alloys fabricated by direct chill (DC) casting often suffers from foundry defects such as cracks and cold shut due to the formidable challenges in the precise controlling of casting parameters. In this manuscript, by using the [...] Read more.
The large-scale ingot of the 7xxx-series aluminum alloys fabricated by direct chill (DC) casting often suffers from foundry defects such as cracks and cold shut due to the formidable challenges in the precise controlling of casting parameters. In this manuscript, by using the integrated computational method combining numerical simulations with machine learning, we systematically estimated the evolution of multi-physical fields and grain structures during the solidification processes. The numerical simulation results quantified the influences of key casting parameters including pouring temperature, casting speed, primary cooling intensity, and secondary cooling water flow rate on the shape of the mushy zone, heat transport, residual stress, and grain structure of DC casting ingots. Then, based on the data of numerical simulations, we established a novel model for the relationship between casting parameters and solidification characteristics through machine learning. By comparing it with experimental measurements, the model showed reasonable accuracy in predicting the sump profile, microstructure evolution, and solidification kinetics under the complicated influences of casting parameters. The integrated computational method and predicting model could be used to efficiently and accurately determine the DC casting parameters to decrease the casting defects. Full article
(This article belongs to the Section Metals and Alloys)
►▼ Show Figures

Figure 1

17 pages, 3440 KiB  
Article
Structure, Antioxidant Activity and Antimicrobial Study of Light Lanthanide Complexes with p-Coumaric Acid
by Grzegorz Świderski, Ewelina Gołębiewska, Natalia Kowalczyk, Monika Kalinowska, Renata Świsłocka, Elżbieta Wołejko, Urszula Wydro, Piotr Malinowski, Anna Pietryczuk, Adam Cudowski, Waldemar Priebe and Włodzimierz Lewandowski
Materials 2024, 17(6), 1324; https://doi.org/10.3390/ma17061324 - 13 Mar 2024
Viewed by 964
Abstract
This paper presents the results of a study of the effects of the lanthanide ions Ce3+, Pr3+, Nd3+ and Sm3+ on the electronic structure and antioxidant and biological (antimicrobial and cytotoxic) properties of p-coumaric acid (p-CAH2 [...] Read more.
This paper presents the results of a study of the effects of the lanthanide ions Ce3+, Pr3+, Nd3+ and Sm3+ on the electronic structure and antioxidant and biological (antimicrobial and cytotoxic) properties of p-coumaric acid (p-CAH2). Structural studies were conducted via spectroscopic methods (FTIR, ATR, UV). Thermal degradation studies of the complexes were performed. The results are presented in the form of TG, DTG and DSC curves. Antioxidant properties were determined via activity tests against DPPH, ABTS and OH radicals. The reducing ability was tested via CUPRAC assays. Minimum inhibitory concentrations (MICs) of the ligand and lanthanide complexes were determined on E. coli, B. subtilis and C. albicans microorganisms. The antimicrobial activity was also determined using the MTT assay. The results were presented as the relative cell viability of C. albicans, P. aeruginosa, E. coli and S. aureus compared to controls and expressed as percentages. In the obtained complexes in the solid phase, lanthanide ions coordinate three ligands in a bidentate chelating coordination mode through the carboxyl group of the acid. Spectroscopic analysis showed that lanthanide ions increase the aromaticity of the pi electron system of the ligand. Thermal analysis showed that the complexes are hydrated and have a higher thermal stability than the ligand. The products of thermal decomposition of the complexes are lanthanide oxides. In the aqueous phase, the metal combines with the ligand in a 1:1 molar ratio. Antioxidant activity tests showed that the complexes have a similar ability to remove free radicals. ABTS and DPPH tests showed that the complexes have twice the ability to neutralise radicals than the ligand, and a much higher ability to remove the hydroxyl radical. The abilities of the complexes and the free ligand to reduce Cu2+ ions in the CUPRAC test are at a similar level. Lanthanide complexes of p-coumaric acid are characterised by a higher antimicrobial capacity than the free ligand against Escherichia coli bacteria, Bacillus subtilis and Candida albicans fungi. Full article
(This article belongs to the Special Issue Synthesis, Modeling, Physico-Chemical and Biological Properties of Metal Complexes)
►▼ Show Figures

Figure 1

23 pages, 15469 KiB  
Article
Interfacial Segregation of Sn during the Continuous Annealing and Selective Oxidation of Fe-Mn-Sn Alloys
by Jonas Wagner and Joseph R. McDermid
Materials 2024, 17(6), 1257; https://doi.org/10.3390/ma17061257 - 8 Mar 2024
Cited by 1 | Viewed by 682
Abstract
The effect of Mn on interfacial Sn segregation during the selective oxidation of Fe-(0–10)Mn-0.03Sn (at.%) alloys was determined for annealing conditions compatible with continuous galvanizing. Significant Sn enrichment was observed at the substrate free surface and metal/oxide interface for all annealing conditions and [...] Read more.
The effect of Mn on interfacial Sn segregation during the selective oxidation of Fe-(0–10)Mn-0.03Sn (at.%) alloys was determined for annealing conditions compatible with continuous galvanizing. Significant Sn enrichment was observed at the substrate free surface and metal/oxide interface for all annealing conditions and Mn levels. Sn enrichment at the free surface was insensitive to the Mn alloy concentration, which was partially attributed to the opposing effects of Mn on segregation thermodynamics and kinetics: Mn increases the driving force for Sn segregation via reducing Sn solubility in Fe but also reduces the effective Sn diffusivity by increasing the austenite volume fraction. This insensitivity was exacerbated by the depletion of solute Mn near the surface due to the selective oxidation of Mn. Thus, Sn segregation occurred in regions with a local Mn concentration lower than the nominal bulk composition of the alloys suggested. Sn enrichment at the metal/external oxide interface was reduced compared to the free surface and decreased with increasing bulk Mn content, which was attributed to changes in the external oxide morphology and metal/internal oxide interfaces acting as Sn sinks. Full article
(This article belongs to the Section Metals and Alloys)
►▼ Show Figures

Figure 1

20 pages, 7712 KiB  
Article
The Influence of the Shielding-Gas Flow Rate on the Mechanical Properties of TIG-Welded Butt Joints of Commercially Pure Grade 1 Titanium
by Krzysztof Szwajka, Joanna Zielińska-Szwajka and Tomasz Trzepieciński
Materials 2024, 17(5), 1217; https://doi.org/10.3390/ma17051217 - 6 Mar 2024
Viewed by 815
Abstract
This article proposes as a novelty the differentiation of shielding-gas flow rates from both sides of the tungsten inert gas (TIG)-welded butt joints of commercially pure (CP) grade 1 titanium tubes. Such an approach is aimed at economically reducing the amount of protective [...] Read more.
This article proposes as a novelty the differentiation of shielding-gas flow rates from both sides of the tungsten inert gas (TIG)-welded butt joints of commercially pure (CP) grade 1 titanium tubes. Such an approach is aimed at economically reducing the amount of protective gas used in TIG closed butt welding. The effect of the shielding-gas flow rate on the properties of CP grade 1 titanium butt-welded joints made using the tungsten inert gas (TIG)-welding method. Butt-welded joints were made for different values of the shielding-gas flow from the side of the root of the weld. Argon 5.0 was used as the shielding gas in the welding process. As part of the research, the welded joints obtained were analysed using optical and scanning electron microscopy. The microstructural characteristics of the joints were examined using an optical microscope, and the mechanical properties were determined using hardness and tensile tests. It was observed that as the flow of the shielding gas decreases, the hardness of the weld material increases and its brittleness also increases. A similar trend related to the amount of gas flow was also noticeable for the tensile strength of the joints. The increase in the hardness of the weld and the heat-affected zone compared to the base metal is mainly related to the increase in the amount of acicular structure (α′ phase). The optimal gas flow rates from the side of the root of weld were found at the values of 12 dm3/min. Full article
(This article belongs to the Special Issue Advances in Welding Techniques, Welding Inspection, and Welding Testing Methods)
►▼ Show Figures

Figure 1

19 pages, 3982 KiB  
Article
Investigation and Validation of a Shape Memory Alloy Material Model Using Interactive Fibre Rubber Composites
by Achyuth Ram Annadata, Aline Iobana Acevedo-Velazquez, Lucas A. Woodworth, Thomas Gereke, Michael Kaliske, Klaus Röbenack and Chokri Cherif
Materials 2024, 17(5), 1163; https://doi.org/10.3390/ma17051163 - 1 Mar 2024
Viewed by 921
Abstract
The growing demand for intelligent systems with improved human-machine interactions has created an opportunity to develop adaptive bending structures. Interactive fibre rubber composites (IFRCs) are created using smart materials as actuators to obtain any desired application using fibre-reinforced elastomer. Shape memory alloys (SMAs) [...] Read more.
The growing demand for intelligent systems with improved human-machine interactions has created an opportunity to develop adaptive bending structures. Interactive fibre rubber composites (IFRCs) are created using smart materials as actuators to obtain any desired application using fibre-reinforced elastomer. Shape memory alloys (SMAs) play a prominent role in the smart material family and are being used for various applications. Their diverse applications are intended for commercial and research purposes, and the need to model and analyse these application-based structures to achieve their maximum potential is of utmost importance. Many material models have been developed to characterise the behaviour of SMAs. However, there are very few commercially developed finite element models that can predict their behaviour. One such model is the Souza and Auricchio (SA) SMA material model incorporated in ANSYS, with the ability to solve for both shape memory effect (SME) and superelasticity (SE) but with a limitation of considering pre-stretch for irregularly shaped geometries. In order to address this gap, Woodworth and Kaliske (WK) developed a phenomenological constitutive SMA material model, offering the flexibility to apply pre-stretches for SMA wires with irregular profiles. This study investigates the WK SMA material model, utilizing deformations observed in IFRC structures as a reference and validating them against simulated models using the SA SMA material model. This validation process is crucial in ensuring the reliability and accuracy of the WK model, thus enhancing confidence in its application for predictive analysis in SMA-based systems. Full article
(This article belongs to the Special Issue Interactive Fiber Rubber Composites—Volume II)
►▼ Show Figures

Figure 1

22 pages, 4276 KiB  
Article
Silver Nanoparticles-Chitosan Nanocomposites: A Comparative Study Regarding Different Chemical Syntheses Procedures and Their Antibacterial Effect
by Dan Chicea, Alexandra Nicolae-Maranciuc and Liana-Maria Chicea
Materials 2024, 17(5), 1113; https://doi.org/10.3390/ma17051113 - 28 Feb 2024
Cited by 1 | Viewed by 757
Abstract
Nanocomposites based on silver nanoparticles and chitosan present important advantages for medical applications, showing over time their role in antibacterial evaluation. This work presents the comparative study of two chemical synthesis procedures of nanocomposites, based on trisodium citrate dihydrate and sodium hydroxide, using [...] Read more.
Nanocomposites based on silver nanoparticles and chitosan present important advantages for medical applications, showing over time their role in antibacterial evaluation. This work presents the comparative study of two chemical synthesis procedures of nanocomposites, based on trisodium citrate dihydrate and sodium hydroxide, using various chitosan concentrations for a complex investigation. The nanocomposites were characterized by AFM and DLS regarding their dimensions, while FT-IR and UV–VIS spectrometry were used for the optical properties and to reveal the binding of silver nanoparticles with chitosan. Their antibacterial effect was determined using a disk diffusion method on two bacteria strains, E. coli and S. aureus. The results indicate that, when using both methods, the nanocomposites obtained were below 100 nm, yet the antibacterial effect proved to be stronger for the nanocomposites obtained using sodium hydroxide. Furthermore, the antibacterial effect can be related to the nanocomposites’ sizes, since the smallest dimension nanocomposites exhibited the best bacterial growth inhibition on both bacteria strains we tested and for both types of silver nanocomposites. Full article
(This article belongs to the Special Issue Nanocomposite Based Materials for Various Applications)
►▼ Show Figures

Figure 1

45 pages, 11151 KiB  
Review
Evaluation of the Embrittlement in Reactor Pressure-Vessel Steels Using a Hybrid Nondestructive Electromagnetic Testing and Evaluation Approach
by Gábor Vértesy, Madalina Rabung, Antal Gasparics, Inge Uytdenhouwen, James Griffin, Daniel Algernon, Sonja Grönroos and Jari Rinta-Aho
Materials 2024, 17(5), 1106; https://doi.org/10.3390/ma17051106 - 28 Feb 2024
Viewed by 992
Abstract
The nondestructive determination of the neutron-irradiation-induced embrittlement of nuclear reactor pressure-vessel steel is a very important and recent problem. Within the scope of the so-called NOMAD project funded by the Euratom research and training program, novel nondestructive electromagnetic testing and evaluation (NDE) methods [...] Read more.
The nondestructive determination of the neutron-irradiation-induced embrittlement of nuclear reactor pressure-vessel steel is a very important and recent problem. Within the scope of the so-called NOMAD project funded by the Euratom research and training program, novel nondestructive electromagnetic testing and evaluation (NDE) methods were applied to the inspection of irradiated reactor pressure-vessel steel. In this review, the most important results of this project are summarized. Different methods were used and compared with each other. The measurement results were compared with the destructively determined ductile-to-brittle transition temperature (DBTT) values. Three magnetic methods, 3MA (micromagnetic, multiparameter, microstructure and stress analysis), MAT (magnetic adaptive testing), and Barkhausen noise technique (MBN), were found to be the most promising techniques. The results of these methods were in good agreement with each other. A good correlation was found between the magnetic parameters and the DBTT values. The basic idea of the NOMAD project is to use a multi-method/multi-parameter approach and to focus on the synergies that allow us to recognize the side effects, therefore suppressing them at the same time. Different types of machine-learning (ML) algorithms were tested in a competitive manner, and their performances were evaluated. The important outcome of the ML technique is that not only one but several different ML techniques could reach the required precision and reliability, i.e., keeping the DBTT prediction error lower than a ±25 °C threshold, which was previously not possible for any of the NDE methods as single entities. A calibration/training procedure was carried out on the merged outcome of the testing methods with excellent results to predict the transition temperature, yield strength, and mechanical hardness for all investigated materials. Our results, achieved within the NOMAD project, can be useful for the future potential introduction of this (and, in general, any) nondestructive evolution method. Full article
(This article belongs to the Section Materials Physics)
►▼ Show Figures

Figure 1

0 pages, 8052 KiB  
Article
Analysis of the Effect of an Open Hole on the Buckling of a Compressed Composite Plate
by Pawel Wysmulski
Materials 2024, 17(5), 1081; https://doi.org/10.3390/ma17051081 - 27 Feb 2024
Cited by 2 | Viewed by 795
Abstract
This paper investigates the effect of an open hole on the stability of a compressed laminated composite plate. The study was carried out in two ways: using experimental tests and numerical analysis. As a result of the experiment, the buckling form and path [...] Read more.
This paper investigates the effect of an open hole on the stability of a compressed laminated composite plate. The study was carried out in two ways: using experimental tests and numerical analysis. As a result of the experiment, the buckling form and path of the plate were recorded. The form of buckling was determined using the ARAMIS non-contact measurement system. The critical load value was determined from the working path using the approximation method. The experimental results were verified by numerical analysis based on the finite element method. FEM investigations were carried out in terms of a linear eigenproblem analysis. This allowed the bifurcation load and the corresponding buckling form of the numerical model of the plate to be determined. Investigating the effect of the hole in the compressed plate at a critical state showed high agreement between the proposed test methods. No clear effect of the hole size on the buckling of the plate was observed. In contrast, a clear effect of the hole on the critical load value was determined. The maximum decrease in the critical load value was 14%. The same decrease was observed for the stiffness of the post-critical characteristics. It was shown that the [45|−45|90|0]s composite plate had more than three times lower strength compared to [0|−45|45|90]s and [0|90|0|90]s. The novelty of this article is the development of a research methodology based on new interdisciplinary research methods for describing the influence of the central hole on the stability of compressed composite plates. The ABAQUS system was used for the numerical analysis. Full article
(This article belongs to the Section Advanced Composites)
►▼ Show Figures

Figure 1

24 pages, 9586 KiB  
Article
The Development of Sustainable Polyethylene Terephthalate Glycol-Based (PETG) Blends for Additive Manufacturing Processing—The Use of Multilayered Foil Waste as the Blend Component
by Mikołaj Garwacki, Igor Cudnik, Damian Dziadowiec, Piotr Szymczak and Jacek Andrzejewski
Materials 2024, 17(5), 1083; https://doi.org/10.3390/ma17051083 - 27 Feb 2024
Viewed by 1460
Abstract
The polymer foil industry is one of the leading producers of plastic waste. The development of new recycling methods for packaging products is one of the biggest demands in today’s engineering. The subject of this research was the melt processing of multilayered PET-based [...] Read more.
The polymer foil industry is one of the leading producers of plastic waste. The development of new recycling methods for packaging products is one of the biggest demands in today’s engineering. The subject of this research was the melt processing of multilayered PET-based foil waste with PETG copolymer. The resulting blends were intended for additive manufacturing processing using the fused deposition modeling (FDM) method. In order to improve the properties of the developed materials, the blends compounding procedure was conducted with the addition of a reactive chain extender (CE) and elastomeric copolymer used as an impact modifier (IM). The samples were manufactured using the 3D printing technique and, for comparison, using the traditional injection molding method. The obtained samples were subjected to a detailed characterization procedure, including mechanical performance evaluation, thermal analysis, and rheological measurements. This research confirms that PET-based film waste can be successfully used for the production of filament, and for most samples, the FDM printing process can be conducted without any difficulties. Unfortunately, the unmodified blends are characterized by brittleness, which makes it necessary to use an elastomer additive (IM). The presence of a semicrystalline PET phase improves the thermal resistance of the prepared blends; however, an annealing procedure is required for this purpose. Full article
(This article belongs to the Special Issue Polymers: From Waste to Potential Reuse)
►▼ Show Figures

Figure 1

32 pages, 5942 KiB  
Article
An Extended Kolmogorov–Avrami–Ishibashi (EKAI) Model to Simulate Dynamic Characteristics of Polycrystalline-Ferroelectric-Gate Field-Effect Transistors
by Shigeki Sakai and Mitsue Takahashi
Materials 2024, 17(5), 1077; https://doi.org/10.3390/ma17051077 - 26 Feb 2024
Viewed by 1444
Abstract
A physics-based model on polarization switching in ferroelectric polycrystalline films is proposed. The calculation results by the model agree well with experimental results regarding dynamic operations of ferroelectric-gate field-effect transistors (FeFETs). In the model, an angle θ for each grain in the ferroelectric [...] Read more.
A physics-based model on polarization switching in ferroelectric polycrystalline films is proposed. The calculation results by the model agree well with experimental results regarding dynamic operations of ferroelectric-gate field-effect transistors (FeFETs). In the model, an angle θ for each grain in the ferroelectric polycrystal is defined, where θ is the angle between the spontaneous polarization and the film normal direction. Under a constant electric field for a single-crystal film with θ = 0, phenomena regarding polarization domain nucleation and wall propagation are well described by the Kolmogorov–Avrami–Ishibashi theory. Since the electric fields are time-dependent in FeFET operations and the θ values are distributed in the polycrystalline film, the model in this paper forms an extended Kolmogorov–Avrami–Ishibashi (EKAI) model. Under a low electric field, the nucleation and domain propagation proceed according to thermally activated processes, meaning that switching the time scale of a grain with the angle θ is proportional to an exponential form as exp(const./Ezcosθ) [Ez: the film-normal electric field]. Wide θ distribution makes the time response quite broad even on the logarithmic scale, which relates well with the broad switching time experimentally shown by FeFETs. The EKAI model is physics based and need not assume non-physical distribution functions in it. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)
►▼ Show Figures

Figure 1

20 pages, 11077 KiB  
Article
Experimental and Theoretical Investigation on Heat Transfer Enhancement in Micro Scale Using Helical Connectors
by Malyne Abraham, Zachary Abboud, Gabriel Herrera Arriaga, Kendall Tom, Samuel Austin and Saeid Vafaei
Materials 2024, 17(5), 1067; https://doi.org/10.3390/ma17051067 - 26 Feb 2024
Cited by 1 | Viewed by 771
Abstract
Microscale electronics have become increasingly more powerful, requiring more efficient cooling systems to manage the higher thermal loads. To meet this need, current research has been focused on overcoming the inefficiencies present in typical thermal management systems due to low Reynolds numbers within [...] Read more.
Microscale electronics have become increasingly more powerful, requiring more efficient cooling systems to manage the higher thermal loads. To meet this need, current research has been focused on overcoming the inefficiencies present in typical thermal management systems due to low Reynolds numbers within microchannels and poor physical properties of the working fluids. For the first time, this research investigated the effects of a connector with helical geometry on the heat transfer coefficient at low Reynolds numbers. The introduction of a helical connector at the inlet of a microchannel has been experimentally tested and results have shown that this approach to flow augmentation has a great potential to increase the heat transfer capabilities of the working fluid, even at low Reynolds numbers. In general, a helical connector can act as a stabilizer or a mixer, based on the characteristics of the connector for the given conditions. When the helical connector acts as a mixer, secondary flows develop that increase the random motion of molecules and possible nanoparticles, leading to an enhancement in the heat transfer coefficient in the microchannel. Otherwise, the heat transfer coefficient decreases. It is widely known that introducing nanoparticles into the working fluids has the potential to increase the thermal conductivity of the base fluid, positively impacting the heat transfer coefficient; however, viscosity also tends to increase, reducing the random motion of molecules and ultimately reducing the heat transfer capabilities of the working fluid. Therefore, optimizing the effects of nanoparticles characteristics while reducing viscous effects is essential. In this study, deionized water and deionized water–diamond nanofluid at 0.1 wt% were tested in a two-microchannel system fitted with a helical connector in between. It was found that the helical connector can make a great heat transfer coefficient enhancement in low Reynolds numbers when characteristics of geometry are optimized for given conditions. Full article
(This article belongs to the Section Advanced Nanomaterials and Nanotechnology)
►▼ Show Figures

Figure 1

22 pages, 5497 KiB  
Article
Synergistic Effects of Co3O4-gC3N4-Coated ZnO Nanoparticles: A Novel Approach for Enhanced Photocatalytic Degradation of Ciprofloxacin and Hydrogen Evolution via Water Splitting
by Abniel Machín, Carmen Morant, Loraine Soto-Vázquez, Edgard Resto, José Ducongé, María Cotto, Pedro J. Berríos-Rolón, Cristian Martínez-Perales and Francisco Márquez
Materials 2024, 17(5), 1059; https://doi.org/10.3390/ma17051059 - 25 Feb 2024
Cited by 1 | Viewed by 1245
Abstract
This research evaluates the efficacy of catalysts based on Co3O4-gC3N4@ZnONPs in the degradation of ciprofloxacin (CFX) and the photocatalytic production of H2 through water splitting. The results show that CFX experiences prompt photodegradation, with [...] Read more.
This research evaluates the efficacy of catalysts based on Co3O4-gC3N4@ZnONPs in the degradation of ciprofloxacin (CFX) and the photocatalytic production of H2 through water splitting. The results show that CFX experiences prompt photodegradation, with rates reaching up to 99% within 60 min. Notably, the 5% (Co3O4-gC3N4)@ZnONPs emerged as the most potent catalyst. The recyclability studies of the catalyst revealed a minimal activity loss, approximately 6%, after 15 usage cycles. Using gas chromatography–mass spectrometry (GC-MS) techniques, the by-products of CFX photodegradation were identified, which enabled the determination of the potential degradation pathway and its resultant products. Comprehensive assessments involving photoluminescence, bandgap evaluations, and the study of scavenger reactions revealed a degradation mechanism driven primarily by superoxide radicals. Moreover, the catalysts demonstrated robust performance in H2 photocatalytic production, with some achieving outputs as high as 1407 µmol/hg in the visible spectrum (around 500 nm). Such findings underline the potential of these materials in environmental endeavors, targeting both water purification from organic pollutants and energy applications. Full article
(This article belongs to the Special Issue Nanoarchitectonics in Materials Science)
►▼ Show Figures

Figure 1

20 pages, 6220 KiB  
Article
The Beneficial Impact of Mineral Content in Spent-Coffee-Ground-Derived Hard Carbon on Sodium-Ion Storage
by Sonya Harizanova, Ivan Uzunov, Lyubomir Aleksandrov, Maria Shipochka, Ivanka Spassova and Mariya Kalapsazova
Materials 2024, 17(5), 1016; https://doi.org/10.3390/ma17051016 - 22 Feb 2024
Cited by 1 | Viewed by 1163
Abstract
The key technological implementation of sodium-ion batteries is converting biomass-derived hard carbons into effective anode materials. This becomes feasible if appropriate knowledge of the relations between the structure of carbonized biomass products, the mineral ash content in them, and Na storage properties is [...] Read more.
The key technological implementation of sodium-ion batteries is converting biomass-derived hard carbons into effective anode materials. This becomes feasible if appropriate knowledge of the relations between the structure of carbonized biomass products, the mineral ash content in them, and Na storage properties is gained. In this study, we examine the simultaneous impact of the ash phase composition and carbon structure on the Na storage properties of hard carbons derived from spent coffee grounds (SCGs). The carbon structure is modified using the pre-carbonization of SCGs at 750 °C, followed by annealing at 1100 °C in an Ar atmosphere. Two variants of the pre-carbonization procedure are adopted: the pre-carbonization of SCGs in a fixed bed and CO2 flow. For the sake of comparison, the pre-carbonized products are chemically treated to remove the ash content. The Na storage performance of SCG-derived carbons is examined in model two and three Na-ion cells. It was found that ash-containing carbons outperformed the ash-free analogs with respect to cycling stability, Coulombic efficiency, and rate capability. The enhanced performance is explained in terms of the modification of the carbon surface by ash phases (mainly albite) and its interaction with the electrolyte, which is monitored by ex situ XPS. Full article
(This article belongs to the Special Issue Size-Dependent Effects in Materials for Environmental Protection and Energy Application)
►▼ Show Figures

Figure 1

44 pages, 14513 KiB  
Review
Hydrogen Impact: A Review on Diffusibility, Embrittlement Mechanisms, and Characterization
by Qidong Li, Hesamedin Ghadiani, Vahid Jalilvand, Tahrim Alam, Zoheir Farhat and Md. Aminul Islam
Materials 2024, 17(4), 965; https://doi.org/10.3390/ma17040965 - 19 Feb 2024
Cited by 7 | Viewed by 2748
Abstract
Hydrogen embrittlement (HE) is a broadly recognized phenomenon in metallic materials. If not well understood and managed, HE may lead to catastrophic environmental failures in vessels containing hydrogen, such as pipelines and storage tanks. HE can affect the mechanical properties of materials such [...] Read more.
Hydrogen embrittlement (HE) is a broadly recognized phenomenon in metallic materials. If not well understood and managed, HE may lead to catastrophic environmental failures in vessels containing hydrogen, such as pipelines and storage tanks. HE can affect the mechanical properties of materials such as ductility, toughness, and strength, mainly through the interaction between metal defects and hydrogen. Various phenomena such as hydrogen adsorption, hydrogen diffusion, and hydrogen interactions with intrinsic trapping sites like dislocations, voids, grain boundaries, and oxide/matrix interfaces are involved in this process. It is important to understand HE mechanisms to develop effective hydrogen resistant strategies. Tensile, double cantilever beam, bent beam, and fatigue tests are among the most common techniques employed to study HE. This article reviews hydrogen diffusion behavior, mechanisms, and characterization techniques. Full article
(This article belongs to the Special Issue Corrosion and Mechanical Behavior of Metal Materials (2nd Edition))
►▼ Show Figures

Figure 1

35 pages, 16769 KiB  
Review
2D Materials Nanoarchitectonics for 3D Structures/Functions
by Katsuhiko Ariga
Materials 2024, 17(4), 936; https://doi.org/10.3390/ma17040936 - 17 Feb 2024
Viewed by 2428
Abstract
It has become clear that superior material functions are derived from precisely controlled nanostructures. This has been greatly accelerated by the development of nanotechnology. The next step is to assemble materials with knowledge of their nano-level structures. This task is assigned to the [...] Read more.
It has become clear that superior material functions are derived from precisely controlled nanostructures. This has been greatly accelerated by the development of nanotechnology. The next step is to assemble materials with knowledge of their nano-level structures. This task is assigned to the post-nanotechnology concept of nanoarchitectonics. However, nanoarchitectonics, which creates intricate three-dimensional functional structures, is not always easy. Two-dimensional nanoarchitectonics based on reactions and arrangements at the surface may be an easier target to tackle. A better methodology would be to define a two-dimensional structure and then develop it into a three-dimensional structure and function. According to these backgrounds, this review paper is organized as follows. The introduction is followed by a summary of the three issues; (i) 2D to 3D dynamic structure control: liquid crystal commanded by the surface, (ii) 2D to 3D rational construction: a metal–organic framework (MOF) and a covalent organic framework (COF); (iii) 2D to 3D functional amplification: cells regulated by the surface. In addition, this review summarizes the important aspects of the ultimate three-dimensional nanoarchitectonics as a perspective. The goal of this paper is to establish an integrated concept of functional material creation by reconsidering various reported cases from the viewpoint of nanoarchitectonics, where nanoarchitectonics can be regarded as a method for everything in materials science. Full article
(This article belongs to the Special Issue Materials Nanoarchitectonics for Membranes, Surfaces, Self-Assembly, and Biomimetics)
►▼ Show Figures

Graphical abstract

11 pages, 8460 KiB  
Article
Development of Antibacterial Resin Composites Incorporating Poly(METAC) Clusters
by Tomoki Kohno, Haruaki Kitagawa, Ririko Tsuboi, Fan Deng, Hirohiko Sakai, Tingyi Wu, Yo-Shiuan Fan, Linghao Xiao and Satoshi Imazato
Materials 2024, 17(4), 896; https://doi.org/10.3390/ma17040896 - 15 Feb 2024
Viewed by 1042
Abstract
This study examined the antibacterial effects and physical properties of a novel resin composite incorporating poly[{2-(methacryloyloxy)ethyl}trimethylammonium chloride] (poly(METAC)), a methacrylate cationic polymer comprising quaternary ammonium compounds (QACs). Resin composites incorporating poly(METAC) were fabricated by adding 6 wt.% METAC aqueous solution to a commercially [...] Read more.
This study examined the antibacterial effects and physical properties of a novel resin composite incorporating poly[{2-(methacryloyloxy)ethyl}trimethylammonium chloride] (poly(METAC)), a methacrylate cationic polymer comprising quaternary ammonium compounds (QACs). Resin composites incorporating poly(METAC) were fabricated by adding 6 wt.% METAC aqueous solution to a commercially available resin composite. The FE-SEM/EDS and Raman spec-troscopy analyses showed that METAC was assembled and polymerized in the resin composites after curing. The antibacterial effect was evaluated by inoculating Streptococcus mutans or Strepto-coccus sobrinus suspensions on the surface of cured resin composites, and the experimental resin composites incorporating poly(METAC) clusters exhibited bactericidal effects even after 28 days of ageing. The physical properties of the experimental resin composites were within the ISO-stipulated ranges. Newly fabricated resin composites containing the QAC-based poly(METAC) cluster ex-hibited long-term bactericidal effects against oral bacteria on their surfaces and demonstrated ac-ceptable physical properties for clinical use. Full article
(This article belongs to the Special Issue Novel Dental Restorative Materials (Volume II))
►▼ Show Figures

Figure 1

12 pages, 3039 KiB  
Article
Atomic-Scale Structural Properties in NiCo2O4/CuFe2O4 Bilayer Heterostructures on (001)-MgAl2O4 Substrate Regulated by Film Thickness
by Kun Liu, Ruyi Zhang, Jiankang Li and Songyou Zhang
Materials 2024, 17(4), 871; https://doi.org/10.3390/ma17040871 - 13 Feb 2024
Cited by 1 | Viewed by 668
Abstract
Changing film thickness to manipulate microstructural properties has been considered as a potential method in practical application. Here, we report that atomic-scale structural properties are regulated by film thickness in an NiCO2O4(NCO)/CuFe2O4(CFO) bilayer heterostructure prepared [...] Read more.
Changing film thickness to manipulate microstructural properties has been considered as a potential method in practical application. Here, we report that atomic-scale structural properties are regulated by film thickness in an NiCO2O4(NCO)/CuFe2O4(CFO) bilayer heterostructure prepared on (001)-MgAl2O4 (MAO) substrate by means of aberration-corrected scanning transmission electron microscopy (STEM). The misfit dislocations at the NCO/CFO interface and antiphase boundaries (APBs) bound to dislocations within the films are both found in NCO (40 nm)/CFO (40 nm)/MAO heterostructures, contributing to the relaxation of mismatch lattice strain. In addition, the non-overlapping a/4[101]-APB is found and the structural transformation of this kind of APB is resolved at the atomic scale. In contrast, only the interfacial dislocations form at the interface without the formation of APBs within the films in NCO (10 nm)/CFO (40 nm)/MAO heterostructures. Our results provide evidence that the formation of microstructural defects can be regulated by changing film thickness to tune the magnetic properties of epitaxial bilayer spinel oxide films. Full article
(This article belongs to the Section Thin Films and Interfaces)
►▼ Show Figures

Figure 1

13 pages, 3072 KiB  
Article
Fabrication and Characterization of an Electrochemical Platform for Formaldehyde Oxidation, Based on Glassy Carbon Modified with Multi-Walled Carbon Nanotubes and Electrochemically Generated Palladium Nanoparticles
by Andrzej Leniart, Barbara Burnat, Mariola Brycht, Maryia-Mazhena Dzemidovich and Sławomira Skrzypek
Materials 2024, 17(4), 841; https://doi.org/10.3390/ma17040841 - 9 Feb 2024
Viewed by 1009
Abstract
This study outlines the fabrication process of an electrochemical platform utilizing glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and palladium nanoparticles (PdNPs). The MWCNTs were applied on the GCE surface using the drop-casting method and PdNPs were produced electrochemically by [...] Read more.
This study outlines the fabrication process of an electrochemical platform utilizing glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and palladium nanoparticles (PdNPs). The MWCNTs were applied on the GCE surface using the drop-casting method and PdNPs were produced electrochemically by a potentiostatic method employing various programmed charges from an ammonium tetrachloropalladate(II) solution. The resulting GCEs modified with MWCNTs and PdNPs underwent comprehensive characterization for topographical and morphological attributes, utilizing atomic force microscopy and scanning electron microscopy along with energy-dispersive X-ray spectrometry. Electrochemical assessment of the GCE/MWCNTs/PdNPs involved cyclic voltammetry (CV) and electrochemical impedance spectroscopy conducted in perchloric acid solution. The findings revealed even dispersion of PdNPs, and depending on the electrodeposition parameters, PdNPs were produced within four size ranges, i.e., 10–30 nm, 20–40 nm, 50–60 nm, and 70–90 nm. Additionally, the electrocatalytic activity toward formaldehyde oxidation was assessed through CV. It was observed that an increase in the size of the PdNPs corresponded to enhanced catalytic activity in the formaldehyde oxidation reaction on the GCE/MWCNTs/PdNPs. Furthermore, satisfactory long-term stability over a period of 42 days was noticed for the GCE/MWCNTs/PDNPs(100) material which demonstrated the best electrocatalytic properties in the electrooxidation reaction of formaldehyde. Full article
(This article belongs to the Special Issue Advanced Electrode Materials Dedicated for Electroanalysis)
►▼ Show Figures

Figure 1

16 pages, 5925 KiB  
Article
Microstructure and Mechanical Properties of Ti-6Al-4V Welds Produced with Different Processes
by Sakari Tolvanen, Robert Pederson and Uta Klement
Materials 2024, 17(4), 782; https://doi.org/10.3390/ma17040782 - 6 Feb 2024
Cited by 1 | Viewed by 847
Abstract
The effect of defects and microstructure on the mechanical properties of Ti-6Al-4V welds produced by tungsten inert gas welding; plasma arc welding; electron beam welding; and laser beam welding was studied in the present work. The mechanical properties of different weld types were [...] Read more.
The effect of defects and microstructure on the mechanical properties of Ti-6Al-4V welds produced by tungsten inert gas welding; plasma arc welding; electron beam welding; and laser beam welding was studied in the present work. The mechanical properties of different weld types were evaluated with respect to micro hardness; yield strength; ultimate tensile strength; ductility; and fatigue at room temperature and at elevated temperatures (200 °C and 250 °C). Metallographic investigation was carried out to characterize the microstructures of different weld types, and fractographic investigation was conducted to relate the effect of defects on fatigue performance. Electron and laser beam welding produced welds with finer microstructure, higher tensile ductility, and better fatigue performance than tungsten inert gas welding and plasma arc welding. Large pores, and pores located close to the specimen surface, were found to be most detrimental to fatigue life. Full article
(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)
►▼ Show Figures

Figure 1

24 pages, 6651 KiB  
Article
Application of Activated Carbons Obtained from Polymer Waste for the Adsorption of Dyes from Aqueous Solutions
by Katarzyna Jedynak and Barbara Charmas
Materials 2024, 17(3), 748; https://doi.org/10.3390/ma17030748 - 4 Feb 2024
Cited by 3 | Viewed by 948
Abstract
Plastic waste disposal is a major environmental problem worldwide. One recycling method for polymeric materials is their conversion into carbon materials. Therefore, a process of obtaining activated carbons through the carbonization of waste CDs (as the selected carbon precursor) in an oxygen-free atmosphere, [...] Read more.
Plastic waste disposal is a major environmental problem worldwide. One recycling method for polymeric materials is their conversion into carbon materials. Therefore, a process of obtaining activated carbons through the carbonization of waste CDs (as the selected carbon precursor) in an oxygen-free atmosphere, and then the physical activation of the obtained material with CO2, was developed. Dyes such as methylene blue (MB) and malachite green (MG) are commonly applied in industry, which contaminate the water environment to a large extent and have a harmful effect on living organisms; therefore, adsorption studies were carried out for these cationic dyes. The effects of the activation time on the physicochemical properties of the activated materials and the adsorption capacity of the dyes were investigated. The obtained microporous adsorbents were characterized by studying the porous structure based on low-temperature nitrogen adsorption/desorption, scanning electron microscopy (SEM-EDS), elemental analysis (CHNS), Raman spectroscopy, X-ray powder diffraction (XRD), infrared spectroscopy (ATR FT-IR), thermal analysis (TG, DTG, DTA), Boehm’s titration method, and pHpzc (the point of zero charge) determination. Moreover, adsorption studies (equilibrium and kinetics) were carried out. The maximum adsorption capacities (qm exp) of MB and MG (349 mg g−1 and 274 mg g−1, respectively) were identified for the obtained material after 8 h of activation. The results show that the use of waste CDs as a carbon precursor facilitates the production of low-cost and effective adsorbents. Full article
(This article belongs to the Special Issue Applications of Polymer Materials: Adsorption, Catalysis, and Degradation)
►▼ Show Figures

Figure 1

16 pages, 10559 KiB  
Article
Mechanical Characterization of Multifunctional Metal-Coated Polymer Lattice Structures
by Lizhe Wang, Liu He, Fuyuan Liu, Hang Yuan, Ji Li and Min Chen
Materials 2024, 17(3), 741; https://doi.org/10.3390/ma17030741 - 3 Feb 2024
Cited by 2 | Viewed by 1378
Abstract
Metal-coated lattice structures hold significant promise for customizing mechanical properties in diverse industrial applications, including the mechanical arms of unmanned aerial vehicles. However, their intricate geometries pose computational challenges, resulting in time-intensive and costly numerical evaluations. This study introduces a parameterization-based multiscale method [...] Read more.
Metal-coated lattice structures hold significant promise for customizing mechanical properties in diverse industrial applications, including the mechanical arms of unmanned aerial vehicles. However, their intricate geometries pose computational challenges, resulting in time-intensive and costly numerical evaluations. This study introduces a parameterization-based multiscale method to analyze body-centered cubic lattice structures with metal coatings. We establish the validity and precision of our proposed method with a comparative analysis of numerical results at the Representative Volume Element (RVE) scale and experimental findings, specifically addressing both elastic tensile and bending stiffness. Furthermore, we showcase the method’s accuracy in interpreting the bending stiffness of coated lattice structures using a homogenized material-based solid model, underscoring its effectiveness in predicting the elastic properties of such structures. In exploring the mechanical characterization of coated lattice structures, we unveil positive correlations between elastic tensile stiffness and both coating thickness and strut diameter. Additionally, the metal coating significantly enhances the structural elastic bending stiffness multiple times over. The diverse failure patterns observed in coated lattices under tensile and bending loads primarily stem from varied loading-induced stress states rather than external factors. This work not only mitigates computational challenges but also successfully bridges the gap between mesoscale RVE mechanical properties and those at the global structural scale. Full article
(This article belongs to the Section Porous Materials)
►▼ Show Figures

Figure 1

15 pages, 5277 KiB  
Article
Improvement of PbSn Solder Reliability with Ge Microalloying-Induced Optimization of Intermetallic Compounds Growth
by Zhibo Qu, Yilong Hao, Changhao Chen, Yong Wang, Shimeng Xu, Shuyuan Shi, Pengrong Lin and Xiaochen Xie
Materials 2024, 17(3), 724; https://doi.org/10.3390/ma17030724 - 2 Feb 2024
Viewed by 765
Abstract
PbSn solders are used in semiconductor devices for aerospace or military purposes with high levels of reliability requirements. Microalloying has been widely adopted to improve the reliability for Pb-free solders, but its application in PbSn solders is scarce. In this article, the optimization [...] Read more.
PbSn solders are used in semiconductor devices for aerospace or military purposes with high levels of reliability requirements. Microalloying has been widely adopted to improve the reliability for Pb-free solders, but its application in PbSn solders is scarce. In this article, the optimization of PbSn solder reliability with Ge microalloying was investigated using both experimental and calculation methods. Intermetallic compounds (IMC) growth and morphologies evolution during reliability tests were considered to be the main factors of device failure. Through first-principle calculation, the growth mechanism of interfacial Ni3Sn4 was discussed, including the formation of vacancies, the Ni-vacancies exchange diffusion and the dominant Ni diffusion along the [1 0 0] direction. The doping of Ge in the cell increased the exchange energy barrier and thus inhibited the IMC development and coarsening trend. In three reliability tests, only 0.013 wt% Ge microalloying in Pb60Sn40 was able to reduce IMC thickness by an increment of 22.6~38.7%. The proposed Ge microalloying method in traditional PbSn solder could yield a prospective candidate for highly reliable applications. Full article
(This article belongs to the Special Issue Advanced Electronic Packaging Technology: From Hard to Soft)
►▼ Show Figures

Figure 1

14 pages, 3622 KiB  
Article
Flexible Dry Electrode Based on a Wrinkled Surface That Uses Carbon Nanotube/Polymer Composites for Recording Electroencephalograms
by Jihyeon Oh, Kun-Woo Nam, Won-Jin Kim, Byung-Ho Kang and Sung-Hoon Park
Materials 2024, 17(3), 668; https://doi.org/10.3390/ma17030668 - 30 Jan 2024
Viewed by 1265
Abstract
Electroencephalography (EEG) captures minute electrical signals emanating from the brain. These signals are vulnerable to interference from external noise and dynamic artifacts; hence, accurately recording such signals is challenging. Although dry electrodes are convenient, their signals are of limited quality; consequently, wet electrodes [...] Read more.
Electroencephalography (EEG) captures minute electrical signals emanating from the brain. These signals are vulnerable to interference from external noise and dynamic artifacts; hence, accurately recording such signals is challenging. Although dry electrodes are convenient, their signals are of limited quality; consequently, wet electrodes are predominantly used in EEG. Therefore, developing dry electrodes for accurately and stably recording EEG signals is crucial. In this study, we developed flexible dry electrodes using polydimethylsiloxane (PDMS)/carbon-nanotube (CNT) composites with isotropically wrinkled surfaces that effectively combine the advantages of wet and dry electrodes. Adjusting the PDMS crosslinker ratio led to good adhesion, resulting in a highly adhesive CNT/PDMS composite with a low Young’s modulus that exhibited excellent electrical and mechanical properties owing to its ability to conformally contact skin. The isotropically wrinkled surface also effectively controls dynamic artifacts during EEG signal detection and ensures accurate signal analysis. The results of this study demonstrate that dry electrodes based on flexible CNT/PDMS composites and corrugated structures can outperform wet electrodes. The introduction of such electrodes is expected to enable the accurate analysis and monitoring of EEG signals in various scenarios, including clinical trials. Full article
(This article belongs to the Special Issue Preparation, Processing, and Application of Advanced Functional Carbon Materials)
►▼ Show Figures

Figure 1

15 pages, 5964 KiB  
Article
Mesoporous Silica MCM-41 from Fly Ash as a Support of Bimetallic Cu/Mn Catalysts for Toluene Combustion
by Jakub Mokrzycki, Monika Fedyna, Dorota Duraczyńska, Mateusz Marzec, Rafał Panek, Wojciech Franus, Tomasz Bajda and Robert Karcz
Materials 2024, 17(3), 653; https://doi.org/10.3390/ma17030653 - 29 Jan 2024
Viewed by 938
Abstract
The main outcome of this research was to demonstrate the opportunity to obtain a stable and well-ordered structure of MCM-41 synthesized from fly ash. A series of bimetallic (Cu/Mn) catalysts supported at MCM-41 were prepared via grinding method and investigated in catalytic toluene [...] Read more.
The main outcome of this research was to demonstrate the opportunity to obtain a stable and well-ordered structure of MCM-41 synthesized from fly ash. A series of bimetallic (Cu/Mn) catalysts supported at MCM-41 were prepared via grinding method and investigated in catalytic toluene combustion reaction to show the material’s potential application. It was proved, that the Cu/Mn ratio had a crucial effect on the catalytic activity of prepared materials. The best catalytic performance was achieved with sample Cu/Mn(2.5/2.5), for which the temperature of 50% toluene conversion was found to be 300 °C. This value remains in line with the literature reports, for which comparable catalytic activity was attained for 3-fold higher metal loadings. Time-on-stream experiment proved the thermal stability of the investigated catalyst Cu/Mn(2.5/2.5). The obtained results bring a valuable background in the field of fly ash utilization, where fly ash-derived MCM-41 can be considered as efficient and stable support for dispersion of active phase for catalyst preparation. Full article
(This article belongs to the Special Issue Applications of Silica and Silica-Based Composites)
►▼ Show Figures

Figure 1

19 pages, 37911 KiB  
Article
Near Net Shape Manufacturing of Sheets from Al-Cu-Li-Mg-Sc-Zr Alloy
by Barbora Kihoulou, Rostislav Králík, Lucia Bajtošová, Olexandr Grydin, Mykhailo Stolbchenko, Mirko Schaper and Miroslav Cieslar
Materials 2024, 17(3), 644; https://doi.org/10.3390/ma17030644 - 28 Jan 2024
Cited by 1 | Viewed by 882
Abstract
Thin twin-roll cast strips from a model Al-Cu-Mg-Li-Zr alloy with a small addition of Sc were prepared. A combination of a fast solidification rate and a favorable effect of Sc microalloying refines the grain size and the size of primary phase particles and [...] Read more.
Thin twin-roll cast strips from a model Al-Cu-Mg-Li-Zr alloy with a small addition of Sc were prepared. A combination of a fast solidification rate and a favorable effect of Sc microalloying refines the grain size and the size of primary phase particles and reduces eutectic cell dimensions to 10–15 μm. Long-term homogenization annealings used in conventionally cast materials lasting several tens of hours followed by a necessary dimension reduction through rolling/extruding could be substituted by energy and material-saving procedure. It consists of two-step short annealings at 300 °C/30 min and 450 °C/30 min, followed by the refinement and hardening of the structure using constrained groove pressing. A dense dispersion of 10–20 nm spherical Al3(Sc,Zr) precipitates intensively forms during this treatment and effectively stabilizes the structure and inhibits the grain growth during subsequent solution treatment at 530 °C/30 min. Small (3%) pre-straining after quenching assures more uniform precipitation of strengthening Al2Cu (θ′), Al2CuMg (S′), and Al2CuLi (T1) particles during subsequent age-hardening annealing at 180 °C/14 h. The material does not contain a directional and anisotropic structure unavoidable in rolled or extruded sheets. The proposed procedure thus represents a model near net shape processing strategy for manufacturing lightweight high-strength sheets for cryogenic applications in aeronautics. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)
►▼ Show Figures

Figure 1

17 pages, 8300 KiB  
Article
The Influence of the Molecular Structure of Compounds on Their Properties and the Occurrence of Chiral Smectic Phases
by Magdalena Urbańska, Monika Zając, Paweł Perkowski and Aleksandra Deptuch
Materials 2024, 17(3), 618; https://doi.org/10.3390/ma17030618 - 27 Jan 2024
Viewed by 880
Abstract
We have designed new chiral smectic mesogens with the -CH2O group near the chiral center. We synthesized two unique rod-like compounds. We determined the mesomorphic properties of these mesogens and confirmed the phase identification using dielectric spectroscopy. Depending on the length [...] Read more.
We have designed new chiral smectic mesogens with the -CH2O group near the chiral center. We synthesized two unique rod-like compounds. We determined the mesomorphic properties of these mesogens and confirmed the phase identification using dielectric spectroscopy. Depending on the length of the oligomethylene spacer (i.e., the number of methylene groups) in the achiral part of the molecules, the studied materials show different phase sequences. Moreover, the temperature ranges of the observed smectic phases are different. It can be seen that as the length of the alkyl chain increases, the liquid crystalline material shows more mesophases. Additionally, its clearing (isotropization) temperature increases. The studied compounds are compared with the structurally similar smectogens previously synthesized. The helical pitch measurements were performed using the selective reflection method. These materials can be useful and effective as chiral components and dopants in smectic mixtures targeted for optoelectronics and photonics. Full article
(This article belongs to the Special Issue Advanced Materials for Luminescent Applications)
►▼ Show Figures

Figure 1

16 pages, 4173 KiB  
Article
The Added Value of a Collagenated Thermosensitive Bone Substitute as a Scaffold for Bone Regeneration
by Charlotte Jeanneau, Jean-Hugues Catherine, Thomas Giraud, Romain Lan and Imad About
Materials 2024, 17(3), 625; https://doi.org/10.3390/ma17030625 - 27 Jan 2024
Viewed by 1183
Abstract
A pre-hydrated thermosensitive collagenated biomaterial which sets at body temperature and maintains the space of the missing alveolar bone volume, OsteoBiol GTO® (GTO), has been released as a bone substitute. This study was designed to check its angiogenic and osteogenic potentials compared [...] Read more.
A pre-hydrated thermosensitive collagenated biomaterial which sets at body temperature and maintains the space of the missing alveolar bone volume, OsteoBiol GTO® (GTO), has been released as a bone substitute. This study was designed to check its angiogenic and osteogenic potentials compared to OsteoBiol Gen-Os® (Gen-Os) and Geistlich Bio-Oss® (Bio-Oss). Samples of materials were incubated in culture media to obtain the extracts. Collagen release was measured in the extracts, which were used to investigate human periodontal ligament (hPDL) cell proliferation (MTT), colonization (Scratch assays) and growth factor release (ELISA). The effects on endothelial cell proliferation (MTT) and organization (Matrigel® assays) were also studied. Finally, endothelial and mesenchymal Stem Cell (hMSC) recruitment (Boyden Chambers) were investigated, and hMSC Alkaline Phosphatase (ALP) activity was measured. A higher collagen concentration was found in GTO extract, which led to significantly higher hPDL cell proliferation/colonization. All materials increased VEGF/FGF-2 growth factor secretion, endothelial cell recruitment, proliferation, and organization, but the increase was highest with GTO. All materials increased hMSC recruitment and ALP activity. However, the increase was highest with collagenated GTO and Gen-Os, which enhanced C5a and BMP-2 secretion. Overall, GTO has higher angiogenic/osteogenic potentials than the collagenated Gen-Os and the anorganic Bio-Oss. It provides a suitable scaffold for endothelial and mesenchymal stem cell recruitment, which represent essential bone regeneration requirements. Full article
(This article belongs to the Special Issue Advances in Biomaterials: Synthesis, Characteristics and Applications)
►▼ Show Figures

Figure 1

11 pages, 1786 KiB  
Article
Rapid Plasma Electrolytic Oxidation Synthesis of Intermetallic PtBi/MgO/Mg Monolithic Catalyst for Efficient Removal of Organic Pollutants
by Jiayi Rong, Mengyang Li, Feng Cao, Qianwei Wang, Mingran Wang, Yang Cao, Jun Zhou and Gaowu Qin
Materials 2024, 17(3), 605; https://doi.org/10.3390/ma17030605 - 26 Jan 2024
Viewed by 736
Abstract
The intermetallic PtBi/MgO/Mg monolithic catalyst was first prepared using non-equilibrium plasma electrolytic oxidation (PEO) technology. Spherical aberration-corrected transmission electron microscope (ACTEM) observation confirms the successful synthesis of the PtBi intermetallic structure. The efficiency of PtBi/Mg/MgO catalysts in catalyzing the reduction of 4-nitrophenol (4-NP) [...] Read more.
The intermetallic PtBi/MgO/Mg monolithic catalyst was first prepared using non-equilibrium plasma electrolytic oxidation (PEO) technology. Spherical aberration-corrected transmission electron microscope (ACTEM) observation confirms the successful synthesis of the PtBi intermetallic structure. The efficiency of PtBi/Mg/MgO catalysts in catalyzing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4 was demonstrated. The activity factor for the catalyst is 31.8 s−1 g−1, which is much higher than reported values. In addition, the resultant catalyst also exhibits excellent catalytic activity in the organic pollutant reaction of p-nitrobenzoic acid (p-NBA) and methyl orange (MO). Moreover, benefiting from ordered atomic structures and the half-embedded PtBi nanoparticles (NPs), the catalyst demonstrates excellent stability and reproducibility in the degradation of 4-NP. This study provides an example of a simple method for the preparation of intermetallic structures as catalysts for organic pollutant degradation. Full article
(This article belongs to the Special Issue Advances in Multicomponent Catalytic Materials)
►▼ Show Figures

Graphical abstract

19 pages, 2228 KiB  
Article
The Design of a Piecewise-Integrated Composite Bumper Beam with Machine-Learning Algorithms
by Seokwoo Ham, Seungmin Ji and Seong Sik Cheon
Materials 2024, 17(3), 602; https://doi.org/10.3390/ma17030602 - 26 Jan 2024
Cited by 1 | Viewed by 807
Abstract
In the present study, a piecewise-integrated composite bumper beam for passenger cars is proposed, and the design innovation process for a composite bumper beam regarding a bumper test protocol suggested by the Insurance Institute for Highway Safety is carried out with the help [...] Read more.
In the present study, a piecewise-integrated composite bumper beam for passenger cars is proposed, and the design innovation process for a composite bumper beam regarding a bumper test protocol suggested by the Insurance Institute for Highway Safety is carried out with the help of machine learning models. Several elements in the bumper FE model have been assigned to be references in order to collect training data, which allow the machine learning model to study the method of predicting loading types for each finite element. Two-dimensional and three-dimensional implementations are provided by machine learning models, which determine the stacking sequences of each finite element in the piecewise-integrated composite bumper beam. It was found that the piecewise-integrated composite bumper beam, which is designed by a machine learning model, is more effective for reducing the possibility of structural failure as well as increasing bending strength compared to the conventional composite bumper beam. Moreover, the three-dimensional implementation produces better results compared with results from the two-dimensional implementation since it is preferable to choose loading-type information, which is achieved from surroundings when the target elements are located either at corners or junctions of planes, instead of using information that comes from the identical plane of target elements. Full article
(This article belongs to the Special Issue Advanced Fiber-Reinforced Composites: Design, Properties and Applications)
►▼ Show Figures

Figure 1

55 pages, 26035 KiB  
Article
On the Importance of the Recovery Procedure in the Semi-Analytical Solution for the Static Analysis of Curved Laminated Panels: Comparison with 3D Finite Elements
by Francesco Tornabene, Matteo Viscoti and Rossana Dimitri
Materials 2024, 17(3), 588; https://doi.org/10.3390/ma17030588 - 25 Jan 2024
Cited by 4 | Viewed by 1130
Abstract
The manuscript presents an efficient semi-analytical solution with three-dimensional capabilities for the evaluation of the static response of laminated curved structures subjected to general external loads. A two-dimensional model is presented based on the Equivalent Single Layer (ESL) approach, where the displacement field [...] Read more.
The manuscript presents an efficient semi-analytical solution with three-dimensional capabilities for the evaluation of the static response of laminated curved structures subjected to general external loads. A two-dimensional model is presented based on the Equivalent Single Layer (ESL) approach, where the displacement field components are described with a generalized formulation based on a higher-order expansion along the thickness direction. The fundamental equations are derived from the Hamiltonian principle, and the solution is found by means of Navier’s approach. Then, an efficient recovery procedure, derived from the three-dimensional elasticity equations and based on the Generalized Differential Quadrature (GDQ) method, is adopted for the derivation of the three-dimensional solution. Some examples of investigation are presented, where the numerical predictions of refined three-dimensional Finite-Element-based models are matched with a high level of accuracy. The model is validated for both straight and curved panels, taking into account different lamination schemes and load shapes. Furthermore, it is shown that the numerical solution to the elasticity problem in the recovery procedure is determining and accurately predicting the three-dimensional static response of the doubly-curved shell solid. Full article
(This article belongs to the Special Issue Multi-scale Modeling of Advanced Materials: Numerical Methods and Experimental Research)
►▼ Show Figures

Figure 1

78 pages, 27700 KiB  
Review
Cryogenic Treatment of Martensitic Steels: Microstructural Fundamentals and Implications for Mechanical Properties and Wear and Corrosion Performance
by Peter Jurči and Ivo Dlouhý
Materials 2024, 17(3), 548; https://doi.org/10.3390/ma17030548 - 23 Jan 2024
Cited by 5 | Viewed by 1261
Abstract
Conventional heat treatment is not capable of converting a sufficient amount of retained austenite into martensite in high-carbon or high-carbon and high-alloyed iron alloys. Cryogenic treatment induces the following alterations in the microstructures: (i) a considerable reduction in the retained austenite amount, (ii) [...] Read more.
Conventional heat treatment is not capable of converting a sufficient amount of retained austenite into martensite in high-carbon or high-carbon and high-alloyed iron alloys. Cryogenic treatment induces the following alterations in the microstructures: (i) a considerable reduction in the retained austenite amount, (ii) formation of refined martensite coupled with an increased number of lattice defects, such as dislocations and twins, (iii) changes in the precipitation kinetics of nano-sized transient carbides during tempering, and (iv) an increase in the number of small globular carbides. These microstructural alterations are reflected in mechanical property improvements and better dimensional stability. A common consequence of cryogenic treatment is a significant increase in the wear resistance of steels. The current review deals with all of the mentioned microstructural changes as well as the variations in strength, toughness, wear performance, and corrosion resistance for a variety of iron alloys, such as carburising steels, hot work tool steels, bearing and eutectoid steels, and high-carbon and high-alloyed ledeburitic cold work tool steels. Full article
(This article belongs to the Special Issue Physical Metallurgy of Metals and Alloys II)
►▼ Show Figures

Figure 1

13 pages, 2282 KiB  
Article
Structural and Photoelectronic Properties of κ-Ga2O3 Thin Films Grown on Polycrystalline Diamond Substrates
by Marco Girolami, Matteo Bosi, Sara Pettinato, Claudio Ferrari, Riccardo Lolli, Luca Seravalli, Valerio Serpente, Matteo Mastellone, Daniele M. Trucchi and Roberto Fornari
Materials 2024, 17(2), 519; https://doi.org/10.3390/ma17020519 - 22 Jan 2024
Cited by 3 | Viewed by 1113
Abstract
Orthorhombic κ-Ga2O3 thin films were grown for the first time on polycrystalline diamond free-standing substrates by metal-organic vapor phase epitaxy at a temperature of 650 °C. Structural, morphological, electrical, and photoelectronic properties of the obtained heterostructures were evaluated by optical [...] Read more.
Orthorhombic κ-Ga2O3 thin films were grown for the first time on polycrystalline diamond free-standing substrates by metal-organic vapor phase epitaxy at a temperature of 650 °C. Structural, morphological, electrical, and photoelectronic properties of the obtained heterostructures were evaluated by optical microscopy, X-ray diffraction, current-voltage measurements, and spectral photoconductivity, respectively. Results show that a very slow cooling, performed at low pressure (100 mbar) under a controlled He flow soon after the growth process, is mandatory to improve the quality of the κ-Ga2O3 epitaxial thin film, ensuring a good adhesion to the diamond substrate, an optimal morphology, and a lower density of electrically active defects. This paves the way for the future development of novel hybrid architectures for UV and ionizing radiation detection, exploiting the unique features of gallium oxide and diamond as wide-bandgap semiconductors. Full article
(This article belongs to the Special Issue Thin Films and Semiconductor Heterostructures: From Fundamental to Applications)
►▼ Show Figures

Figure 1

12 pages, 4522 KiB  
Article
Impact of Glass Free Volume on Femtosecond Laser-Written Nanograting Formation in Silica Glass
by Nadezhda Shchedrina, Maxime Cavillon, Julien Ari, Nadège Ollier and Matthieu Lancry
Materials 2024, 17(2), 502; https://doi.org/10.3390/ma17020502 - 20 Jan 2024
Cited by 1 | Viewed by 937
Abstract
In this study, we investigate the effects of densification through high pressure and temperature (up to 5 GPa, 1000 °C) in the making of nanogratings in pure silica glass, inscribed with femtosecond laser. The latter were monitored through retardance measurements using polarized optical [...] Read more.
In this study, we investigate the effects of densification through high pressure and temperature (up to 5 GPa, 1000 °C) in the making of nanogratings in pure silica glass, inscribed with femtosecond laser. The latter were monitored through retardance measurements using polarized optical microscopy, and their internal structure was observed under scanning electron microscopy. We reveal the difficulty in making nanogratings in densified silica glasses. Based on this observation, we propose that free volume may be a key precursor to initiate nanograting formation. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)
►▼ Show Figures

Figure 1

18 pages, 24962 KiB  
Article
Feasibility Study on the Generation of Nanoporous Metal Structures by Means of Selective Alloy Depletion in Halogen-Rich Atmospheres
by Jörg Weise, Birgit Uhrlaub, Dirk Lehmhus, Joachim Baumeister, Kerstin Hantzsche and Karsten Thiel
Materials 2024, 17(2), 498; https://doi.org/10.3390/ma17020498 - 20 Jan 2024
Viewed by 722
Abstract
A new approach to produce nanoporous metals has been investigated, which is based on the dealloying of bi- or multi-component alloys. Depletion and pore formation of the alloy substrate are obtained by the transport of certain alloy components at high temperatures via volatile [...] Read more.
A new approach to produce nanoporous metals has been investigated, which is based on the dealloying of bi- or multi-component alloys. Depletion and pore formation of the alloy substrate are obtained by the transport of certain alloy components at high temperatures via volatile halogen compounds. These halogen compounds are transferred to materials acting as sinks based on their higher affinity to the respective components, and chemically bound there. Transfer via volatile halogen compounds is known from the pack cementation coating process and from high-temperature corrosion in certain industrial atmospheres. The approach was tested on different precursor alloys: Ti-43.5Al-4Nb-1Mo-0.1B (TNM-B1), TiNb42, and AlCu. Both dealloying effects and micro-scale pore formation were observed. The detailed size of the porous structures is in the range of 50 nm for both TNM-B1 and TiNB42 and 500 nm for AlCu. Full article
(This article belongs to the Section Porous Materials)
►▼ Show Figures

Figure 1

19 pages, 765 KiB  
Article
Dynamics of a Magnetic Polaron in an Antiferromagnet
by Kaijun Shen, Maxim F. Gelin, Kewei Sun and Yang Zhao
Materials 2024, 17(2), 469; https://doi.org/10.3390/ma17020469 - 18 Jan 2024
Viewed by 934
Abstract
The t-J model remains an indispensable construct in high-temperature superconductivity research, bridging the gap between charge dynamics and spin interactions within antiferromagnetic matrices. This study employs the multiple Davydov Ansatz method with thermo-field dynamics to dissect the zero-temperature and finite-temperature behaviors. We uncover [...] Read more.
The t-J model remains an indispensable construct in high-temperature superconductivity research, bridging the gap between charge dynamics and spin interactions within antiferromagnetic matrices. This study employs the multiple Davydov Ansatz method with thermo-field dynamics to dissect the zero-temperature and finite-temperature behaviors. We uncover the nuanced dependence of hole and spin deviation dynamics on the spin–spin coupling parameter J, revealing a thermally-activated landscape where hole mobilities and spin deviations exhibit a distinct temperature-dependent relationship. This numerically accurate thermal perspective augments our understanding of charge and spin dynamics in an antiferromagnet. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)
►▼ Show Figures

Figure 1

15 pages, 2605 KiB  
Review
Divalent Metal Ion Depletion from Wastewater by RVC Cathodes: A Critical Review
by Alessandro Dell’Era, Carla Lupi, Erwin Ciro, Francesca A. Scaramuzzo and Mauro Pasquali
Materials 2024, 17(2), 464; https://doi.org/10.3390/ma17020464 - 18 Jan 2024
Viewed by 766
Abstract
In this paper, a critical review of results obtained using a reticulated vitreous carbon (RVC) three-dimensional cathode for the electrochemical depletion of various divalent ions, such as Cu+2, Cd+2, Pb+2, Zn+2, Ni+2, and [...] Read more.
In this paper, a critical review of results obtained using a reticulated vitreous carbon (RVC) three-dimensional cathode for the electrochemical depletion of various divalent ions, such as Cu+2, Cd+2, Pb+2, Zn+2, Ni+2, and Co+2, often present in wastewater, has been carried out. By analyzing the kinetics and fluid dynamics of the process found in literature, a general dimensionless equation, Sh = f(Re), has been determined, describing a general trend for all the analyzed systems regardless of the geometry, dimensions, and starting conditions. Thus, a map in the log(Sh) vs. log(Re) plane has been reported by characterizing the whole ion electrochemical depletion process and highlighting the existence of a good correlation among all the results. Moreover, because in recent years, the interest in using this three-dimensional cathode material seems to have slowed, the intent is to revive it as a useful tool for metal recovery, recycling processes, and water treatments. Full article
(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)
►▼ Show Figures

Figure 1

23 pages, 425 KiB  
Review
A Review of Modeling of Composite Structures
by Wenbin Yu
Materials 2024, 17(2), 446; https://doi.org/10.3390/ma17020446 - 17 Jan 2024
Cited by 1 | Viewed by 2499
Abstract
This paper provides a brief review on modeling of composite structures. Composite structures in this paper refer to any structure featuring anisotropy and heterogeneity, including but not limited to their traditional meaning of composite laminates made of unidirectional fiber-reinforced composites. Common methods used [...] Read more.
This paper provides a brief review on modeling of composite structures. Composite structures in this paper refer to any structure featuring anisotropy and heterogeneity, including but not limited to their traditional meaning of composite laminates made of unidirectional fiber-reinforced composites. Common methods used in modeling of composite structures, including the axiomatic method, the formal asymptotic method, and the variational asymptotic method, are illustrated in deriving the classical lamination theory for the composite laminated plates. Future research directions for modeling composite structures are also pointed out. Full article
(This article belongs to the Special Issue Methodology of the Design and Testing of Composite Structures)
►▼ Show Figures

Figure 1

15 pages, 11105 KiB  
Article
Influence of Porosity on Fatigue Behaviour of 18Ni300 Steel SLM CT Specimens at Various Angles
by Pablo M. Cerezo, Jose A. Aguilera, Antonio Garcia-Gonzalez and Pablo Lopez-Crespo
Materials 2024, 17(2), 432; https://doi.org/10.3390/ma17020432 - 16 Jan 2024
Cited by 2 | Viewed by 911
Abstract
In order to improve understanding of the fatigue behaviour in additive manufactured samples, this research delves into the challenging interplay between building parameters, particularly fabrication angles, and the presence of pores. The primary objective is to explore the characterisation of these pores and [...] Read more.
In order to improve understanding of the fatigue behaviour in additive manufactured samples, this research delves into the challenging interplay between building parameters, particularly fabrication angles, and the presence of pores. The primary objective is to explore the characterisation of these pores and unravel their relationship with the fatigue properties of the material under investigation. Through a systematic analysis of porosity distribution in various fabrication orientations, supplemented by a detailed examination of the elemental dispersion around specific porous structures using energy-dispersive X-ray spectroscopy, a consistent behavioural pattern emerges across the samples. In assessing fatigue behaviour, an examination of the variables reveals that only area and aspect ratio significantly influence the behaviour of the samples. Such studies can contribute substantially to academic research in the field of material science and engineering. Full article
(This article belongs to the Special Issue Fatigue Crack Growth in Metallic Materials (Volume II))
►▼ Show Figures

Figure 1

13 pages, 5795 KiB  
Article
Characterization of Tannic Acid-Coated AZ31 Mg Alloy for Biomedical Application and Comparison with AZ91
by Jacopo Barberi, Muhammad Saqib, Anna Dmitruk, Jörg Opitz, Krzysztof Naplocha, Natalia Beshchasna, Silvia Spriano and Sara Ferraris
Materials 2024, 17(2), 343; https://doi.org/10.3390/ma17020343 - 10 Jan 2024
Viewed by 958
Abstract
Magnesium alloys are promising materials for bioresorbable implants that will improve patient life and reduce healthcare costs. However, their clinical use is prevented by the rapid degradation and corrosion of magnesium, which leads to a fast loss of mechanical strength and the formation [...] Read more.
Magnesium alloys are promising materials for bioresorbable implants that will improve patient life and reduce healthcare costs. However, their clinical use is prevented by the rapid degradation and corrosion of magnesium, which leads to a fast loss of mechanical strength and the formation of by-products that can trigger tissue inflammation. Here, a tannic acid coating is proposed to control the degradation of AZ31 and AZ91 alloys, starting from a previous study by the authors on AZ91. The coatings on the two materials were characterized both by the chemical (EDS, FTIR, XPS) and the morphological (SEM, confocal profilometry) point of view. Static degradation tests in PBS and electrochemical measurements in different solutions showed that the protective performances of the tannic acid coatings are strongly affected by the presence of cracks. The presence of fractures in the protective layer generates galvanic couples between the coating scales and the metal, worsening the corrosion resistance. Although degradation control was not achieved, useful insights on the degradation mechanisms of coated Mg surfaces were obtained, as well as key points for future studies: it resulted that the absence of cracks in protective coatings is of uttermost importance for novel biodegradable implants with proper degradation kinetics. Full article
(This article belongs to the Special Issue Biocompatible and Bioactive Materials for Medical Applications)
►▼ Show Figures

Figure 1

22 pages, 8943 KiB  
Article
Possibilities of Increasing the Durability of Dies Used in the Extrusion Process of Valve Forgings from Chrome-Nickel Steel by Using Alternative Materials from Hot-Work Tool Steels
by Marek Hawryluk, Marta Janik, Maciej Zwierzchowski, Marzena Małgorzata Lachowicz and Jakub Krawczyk
Materials 2024, 17(2), 346; https://doi.org/10.3390/ma17020346 - 10 Jan 2024
Cited by 1 | Viewed by 809
Abstract
This study refers to an analysis of the dies used in the first operation of producing a valve forging from chromium-nickel steel NC3015. The analyzed process of manufacturing forgings of exhaust valves is realized in the co-extrusion technology, followed by forging in closed [...] Read more.
This study refers to an analysis of the dies used in the first operation of producing a valve forging from chromium-nickel steel NC3015. The analyzed process of manufacturing forgings of exhaust valves is realized in the co-extrusion technology, followed by forging in closed dies. This type of technology is difficult to master, mainly due to the increased adhesion of the charge material to the tool substrate as well as the complex conditions of the tools’ operations, which are caused by the cyclic thermo-mechanical loads and also the hard tribological conditions. The average durability of tools made from tool steel WLV (1.2365), subjected to thermal treatment and nitriding, equals about 1000 forgings. In order to perform an in-depth analysis, a complex analysis of the presently realized technology was conducted in combination with multi-variant numerical simulations. The obtained results showed numerous cracks on the tools, especially in the cross-section reduction area, as well as sticking of the forging material, which, with insufficient control of the tribological conditions, can cause premature wear of the dies. In order to increase the durability of forging dies, alternative materials made of hot work tool steels were used: QRO90 Supreme, W360, and Unimax. The preliminary tests showed that the best results were obtained for QRO90, as the average durability for the tools made of this steel equaled about 1200 forgings (with an increase in both the minimal and maximal values), with reference to the 1000 forgings for the material applied so far. Full article
(This article belongs to the Special Issue Enhancing In-Use Properties of Advanced Steels)
►▼ Show Figures

Figure 1

22 pages, 4577 KiB  
Review
Challenges for Field-Effect-Transistor-Based Graphene Biosensors
by Takao Ono, Satoshi Okuda, Shota Ushiba, Yasushi Kanai and Kazuhiko Matsumoto
Materials 2024, 17(2), 333; https://doi.org/10.3390/ma17020333 - 9 Jan 2024
Cited by 6 | Viewed by 2807
Abstract
Owing to its outstanding physical properties, graphene has attracted attention as a promising biosensor material. Field-effect-transistor (FET)-based biosensors are particularly promising because of their high sensitivity that is achieved through the high carrier mobility of graphene. However, graphene-FET biosensors have not yet reached [...] Read more.
Owing to its outstanding physical properties, graphene has attracted attention as a promising biosensor material. Field-effect-transistor (FET)-based biosensors are particularly promising because of their high sensitivity that is achieved through the high carrier mobility of graphene. However, graphene-FET biosensors have not yet reached widespread practical applications owing to several problems. In this review, the authors focus on graphene-FET biosensors and discuss their advantages, the challenges to their development, and the solutions to the challenges. The problem of Debye screening, in which the surface charges of the detection target are shielded and undetectable, can be solved by using small-molecule receptors and their deformations and by using enzyme reaction products. To address the complexity of sample components and the detection mechanisms of graphene-FET biosensors, the authors outline measures against nonspecific adsorption and the remaining problems related to the detection mechanism itself. The authors also introduce a solution with which the molecular species that can reach the sensor surfaces are limited. Finally, the authors present multifaceted approaches to the sensor surfaces that provide much information to corroborate the results of electrical measurements. The measures and solutions introduced bring us closer to the practical realization of stable biosensors utilizing the superior characteristics of graphene. Full article
(This article belongs to the Special Issue Research Progress on Two-Dimensional Materials)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying article 1-50 on page 1 of 35.

Go to page    1 2 3 4 5 chevron_right last_page
Back to TopTop