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Materials, Volume 17, Issue 5 (March-1 2024) – 259 articles

Cover Story (view full-size image): This research assesses the effectiveness of Co3O4-gC3N4@ZnONPs catalysts in breaking down ciprofloxacin (CFX) and producing hydrogen (H2) via water splitting. Findings reveal that CFX undergoes rapid photodegradation, achieving up to a 99% reduction in 60 minutes, with 5%(Co3O4-gC3N4)@ZnONPs identified as the most efficient catalyst. Recyclability tests showed only a 6% decrease in activity after 15 cycles. The degradation pathway and by-products of CFX were identified using GC-MS, pointing towards a mechanism largely driven by superoxide radicals. Moreover, these catalysts displayed strong capability in generating H2, with outputs reaching 1407 µmol/hg in the visible light range. This highlights their potential for use in environmental cleanup and energy production. View this paper
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22 pages, 2943 KiB  
Article
Biocomposite Materials Derived from Andropogon halepensis: Eco-Design and Biophysical Evaluation
by Marcela-Elisabeta Barbinta-Patrascu, Cornelia Nichita, Bogdan Bita and Stefan Antohe
Materials 2024, 17(5), 1225; https://doi.org/10.3390/ma17051225 - 06 Mar 2024
Viewed by 692
Abstract
This research work presents a “green” strategy of weed valorization for developing silver nanoparticles (AgNPs) with promising interesting applications. Two types of AgNPs were phyto-synthesized using an aqueous leaf extract of the weed Andropogon halepensis L. Phyto-manufacturing of AgNPs was achieved by two [...] Read more.
This research work presents a “green” strategy of weed valorization for developing silver nanoparticles (AgNPs) with promising interesting applications. Two types of AgNPs were phyto-synthesized using an aqueous leaf extract of the weed Andropogon halepensis L. Phyto-manufacturing of AgNPs was achieved by two bio-reactions, in which the volume ratio of (phyto-extract)/(silver salt solution) was varied. The size and physical stability of Andropogon—AgNPs were evaluated by means of DLS and zeta potential measurements, respectively. The phyto-developed nanoparticles presented good free radicals-scavenging properties (investigated via a chemiluminescence technique) and also urease inhibitory activity (evaluated using the conductometric method). Andropogon—AgNPs could be promising candidates for various bio-applications, such as acting as an antioxidant coating for the development of multifunctional materials. Thus, the Andropogon-derived samples were used to treat spider silk from the spider Pholcus phalangioides, and then, the obtained “green” materials were characterized by spectral (UV-Vis absorption, FTIR ATR, and EDX) and morphological (SEM) analyses. These results could be exploited to design novel bioactive materials with applications in the biomedical field. Full article
(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures)
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24 pages, 7943 KiB  
Article
Electrical and Electro-Thermal Characteristics of (Carbon Black-Graphite)/LLDPE Composites with PTC Effect
by Eduard-Marius Lungulescu, Cristina Stancu, Radu Setnescu, Petru V. Notingher and Teodor-Adrian Badea
Materials 2024, 17(5), 1224; https://doi.org/10.3390/ma17051224 - 06 Mar 2024
Viewed by 631
Abstract
Electrical properties and electro-thermal behavior were studied in composites with carbon black (CB) or hybrid filler (CB and graphite) and a matrix of linear low-density polyethylene (LLDPE). LLDPE, a (co)polymer with low crystallinity but with high structural regularity, was less studied for Positive [...] Read more.
Electrical properties and electro-thermal behavior were studied in composites with carbon black (CB) or hybrid filler (CB and graphite) and a matrix of linear low-density polyethylene (LLDPE). LLDPE, a (co)polymer with low crystallinity but with high structural regularity, was less studied for Positive Temperature Coefficient (PTC) applications, but it would be of interest due to its higher flexibility as compared to HDPE. Structural characterization by scanning electron microscopy (SEM) confirmed a segregated structure resulted from preparation by solid state powder mixing followed by hot molding. Direct current (DC) conductivity measurements resulted in a percolation threshold of around 8% (w) for CB/LLDPE composites. Increased filler concentrations resulted in increased alternating current (AC) conductivity, electrical permittivity and loss factor. Resistivity-temperature curves indicate the dependence of the temperature at which the maximum of resistivity is reached (Tmax(R)) on the filler concentration, as well as a differentiation in the Tmax(R) from the crystalline transition temperatures determined by DSC. These results suggest that crystallinity is not the only determining factor of the PTC mechanism in this case. This behavior is different from similar high-crystallinity composites, and suggests a specific interaction between the conductive filler and the polymeric matrix. A strong dependence of the PTC effect on filler concentration and an optimal concentration range between 14 and 19% were also found. Graphite has a beneficial effect not only on conductivity, but also on PTC behavior. Temperature vs. time experiments, revealed good temperature self-regulation properties and current and voltage limitation, and irrespective of the applied voltage and composite type, the equilibrium superficial temperature did not exceed 80 °C, while the equilibrium current traversing the sample dropped from 22 mA at 35 V to 5 mA at 150 V, proving the limitation capacities of these materials. The concentration effects revealed in this work could open new perspectives for the compositional control of both the self-limiting and interrupting properties for various low-temperature applications. Full article
(This article belongs to the Special Issue Advances in Polymer Blends and Composites)
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21 pages, 14659 KiB  
Article
Evaluation of Microstructure and Abrasive Wear-Resistance of Medium Alloy SiMo Ductile Cast Iron
by Łukasz Dyrlaga, Renata Zapała, Krzysztof Morgiel, Andrzej Studnicki, Andrzej Szczęsny and Dariusz Kopyciński
Materials 2024, 17(5), 1223; https://doi.org/10.3390/ma17051223 - 06 Mar 2024
Viewed by 542
Abstract
Medium-alloy ductile iron with a SiMo ferritic matrix has very good heat resistance. The addition of chromium and aluminum also increases this resistance. This article presents the impact of chromium and aluminum on the structure of SiMo cast iron, especially their impact on [...] Read more.
Medium-alloy ductile iron with a SiMo ferritic matrix has very good heat resistance. The addition of chromium and aluminum also increases this resistance. This article presents the impact of chromium and aluminum on the structure of SiMo cast iron, especially their impact on the deformation of the spherical graphite precipitates and the formation of M6C and M3C2 carbide phases. These carbides are formed in a ferritic matrix or at the grain boundaries, resulting in increased hardness and a drastic reduction in impact strength. The article presents the influence of heat treatment on the material’s microstructure and resistance to abrasive wear. Chromium and aluminum additions can also indirectly reduce the abrasive wear resistance of SiMo cast iron. The presented research shows the possibility of doubling the abrasive wear resistance of SiMo cast iron. Full article
(This article belongs to the Special Issue Research and Development in the World Foundry Engineering: Materials, Properties and Applications)
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29 pages, 6030 KiB  
Review
Properties of Cementitious Materials Utilizing Seashells as Aggregate or Cement: Prospects and Challenges
by Yunpeng Zhu, Da Chen, Xiaotong Yu, Ruiwen Liu and Yingdi Liao
Materials 2024, 17(5), 1222; https://doi.org/10.3390/ma17051222 - 06 Mar 2024
Viewed by 1325
Abstract
Nowadays, the sustainable development of the construction industry has become a focus of attention. Crushing and grinding waste seashells originating from the fishery industry, such as oyster shells, cockle shells, mussel shells, and scallop shells, into different particle sizes for usage as aggregate [...] Read more.
Nowadays, the sustainable development of the construction industry has become a focus of attention. Crushing and grinding waste seashells originating from the fishery industry, such as oyster shells, cockle shells, mussel shells, and scallop shells, into different particle sizes for usage as aggregate and cement in concrete or mortar provides an effective and sustainable solution to environmental problems by reducing natural resource dependence. Numerous studies have attempted to analyze the suitability of waste seashell as a possible alternative to natural aggregates and cement in concrete or mortar. This paper presents an up-to-date review of the characteristics of different types of waste seashell, as well as the physical, mechanical, durability, and other notable functional properties of seashell concrete or mortar. From the outcome of the research, waste seashell could be an inert material, and it is important to conduct a series of proper treatment for a better-quality material. It is also seen from the results that although the mechanical properties of seashell concrete have been reduced, they all meet the required criteria set by various international standards and codes. Therefore, it is recommended that the replacement of seashells as aggregate and cement should not exceed 20% and 5%, respectively. Seashell concrete or mortar would then have sufficient workability and strength for non-structural purposes. However, there is still a lack of investigation concerning the different properties of reinforced concrete members using seashells as the replacement of aggregate or cement. Further innovative research can solidify its utilization towards sustainable development. Full article
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15 pages, 436 KiB  
Review
Soft Tissue Substitutes in Periodontal and Peri-Implant Soft Tissue Augmentation: A Systematic Review
by Roberto Rotundo, Gian Luca Pancrazi, Alessia Grassi, Lara Ceresoli, Giovanna Laura Di Domenico and Vanessa Bonafede
Materials 2024, 17(5), 1221; https://doi.org/10.3390/ma17051221 - 06 Mar 2024
Viewed by 718
Abstract
Background: Different extracellular matrix (ECM)-based technologies in periodontal and peri-implant soft tissue augmentation have been proposed in the market. The present review compared the efficacy of soft tissue substitutes (STSs) and autogenous free gingival grafts (FGGs) or connective tissue grafts (CTGs) in mucogingival [...] Read more.
Background: Different extracellular matrix (ECM)-based technologies in periodontal and peri-implant soft tissue augmentation have been proposed in the market. The present review compared the efficacy of soft tissue substitutes (STSs) and autogenous free gingival grafts (FGGs) or connective tissue grafts (CTGs) in mucogingival procedures to increase keratinized tissue (KT) width around teeth and implants. Methods: Two independent examiners performed an electronic search on MEDLINE and the Cochrane Library based on the following PICOS format: (P) adult patients; (I) soft tissue substitutes and FGGs/CTGs; (C) STSs vs. CTGs; STSs vs. FGGs; STSs vs control; (O) KT width gain; (S) systematic reviews, randomized controlled trials. Studies published before November 2023 were included. Results: Around teeth, all biomaterials showed superior performance compared to a coronally advanced flap (CAF) alone for treating gingival recessions. However, when compared to CTGs, acellular dermal matrices (ADMs) yield the most similar outcomes to the gold standard (CTGs), even though in multiple recessions, CTGs continue to be considered the most favorable approach. The use of STSs (acellular matrix or tissue-engineered) in combination with apically positioned flaps (APF) resulted in significantly less gain in KT width compared to that achieved with FGGs and APFs. Around dental implants, free gingival grafts were deemed more effective than soft tissue substitutes in enhancing keratinized mucosa width. Conclusions: Based on the available evidence, questions remain about the alternative use of soft tissue substitutes for conventional grafting procedures using free gingival grafts or connective tissue grafts around teeth and implants. Full article
(This article belongs to the Special Issue Materials and Devices for Multidisciplinary Dental Treatments)
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12 pages, 9954 KiB  
Article
Amino-Modified Graphene Oxide from Kish Graphite for Enhancing Corrosion Resistance of Waterborne Epoxy Coatings
by Shengle Hao, Siming Wan, Shiyu Hou, Bowen Yuan, Chenhui Luan, Ding Nan, Gen Huang, Deping Xu and Zheng-Hong Huang
Materials 2024, 17(5), 1220; https://doi.org/10.3390/ma17051220 - 06 Mar 2024
Viewed by 502
Abstract
Waterborne epoxy (WEP) coatings with enhanced corrosion resistance were prepared using graphene oxide (GO) that was obtained from kish graphite, and amino-functionalized graphene oxide (AGO) was modified by 2-aminomalonamide. The structural characteristics of the GO and AGO were analyzed using X-ray diffraction (XRD), [...] Read more.
Waterborne epoxy (WEP) coatings with enhanced corrosion resistance were prepared using graphene oxide (GO) that was obtained from kish graphite, and amino-functionalized graphene oxide (AGO) was modified by 2-aminomalonamide. The structural characteristics of the GO and AGO were analyzed using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). And the anti-corrosive performance of waterborne epoxy-cased composite coatings with different addition amounts of AGO was investigated using electrochemical measurements, pull-off adhesion tests, and salt spray tests. The results indicate that AGO15/WEP with 0.15 wt.% of AGO has the best anti-corrosive performance, and the lowest frequency impedance modulus increased from 1.03 × 108 to 1.63 × 1010 ohm·cm−2 compared to that of WEP. Furthermore, AGO15/WEP also demonstrates the minimal corrosion products or bubbles in the salt spray test for 200 h, affirming its exceptional long-term corrosion protection capability. Full article
(This article belongs to the Section Carbon Materials)
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9 pages, 1875 KiB  
Article
Influence of Accelerators on Cement Mortars Using Fluid Catalytic Cracking Catalyst Residue (FCC): Enhanced Mechanical Properties at Early Curing Ages
by Lourdes Soriano, María Victoria Borrachero, Ester Giménez-Carbo, Mauro M. Tashima, José María Monzó and Jordi Payá
Materials 2024, 17(5), 1219; https://doi.org/10.3390/ma17051219 - 06 Mar 2024
Viewed by 451
Abstract
Supplementary cementitious materials (SCMs) have been used in the construction industry to mainly reduce the greenhouse gas emissions associated with Portland cement. Of SCMs, the petrochemical industry waste known as fluid catalytic cracking catalyst residue (FCC) is recognized for its high reactivity. Nevertheless, [...] Read more.
Supplementary cementitious materials (SCMs) have been used in the construction industry to mainly reduce the greenhouse gas emissions associated with Portland cement. Of SCMs, the petrochemical industry waste known as fluid catalytic cracking catalyst residue (FCC) is recognized for its high reactivity. Nevertheless, the binders produced using SCMs usually present low mechanical strength at early curing ages. This study aims to assess the effect of different accelerating additives (KOH, sodium silicate SIL, commercial additive SKR) on the mechanical strength of mortars containing FCC. The results show that after only 8 curing hours, the compressive strength gain of the FCC mortars containing SKR was over 100% compared to the FCC mortar with no additive (26.0 vs. 12.8 MPa). Comparing the compressive strength of FCC mortar containing SKR to the control mortar, the enhancement is spetacular (6.85 vs. 26.03 MPa). The effectiveness of the tested accelerators at 8–24 curing hours was KOH ≈ SIL < SKR, whereas it was KOH < SIL < SKR for 48 h–28 days. The thermogravimetric data confirmed the good compatibility of FCC and the commercial accelerator. Full article
(This article belongs to the Special Issue Advances in the Design and Properties of New Ecoconcrete Formulations)
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14 pages, 5935 KiB  
Article
Suitability of Gelatin Methacrylate and Hydroxyapatite Hydrogels for 3D-Bioprinted Bone Tissue
by Paul Stolarov, Jonathan de Vries, Sean Stapleton, Lauren Morris, Kari Martyniak and Thomas J. Kean
Materials 2024, 17(5), 1218; https://doi.org/10.3390/ma17051218 - 06 Mar 2024
Viewed by 1158
Abstract
Background: Complex bone defects are challenging to treat. Autografting is the gold standard for regenerating bone defects; however, its limitations include donor-site morbidity and increased surgical complexity. Advancements in 3D bioprinting (3DBP) offer a promising alternative for viable bone grafts. In this experiment, [...] Read more.
Background: Complex bone defects are challenging to treat. Autografting is the gold standard for regenerating bone defects; however, its limitations include donor-site morbidity and increased surgical complexity. Advancements in 3D bioprinting (3DBP) offer a promising alternative for viable bone grafts. In this experiment, gels composed of varying levels of gelatin methacrylate (GelMA) and hydroxyapatite (HA) and gelatin concentrations are explored. The objective was to increase the hydroxyapatite content and find the upper limit before the printability was compromised and determine its effect on the mechanical properties and cell viability. Methods: Design of Experiments (DoE) was used to design 13 hydrogel bioinks of various GelMA/HA concentrations. These bioinks were assessed in terms of their pipettability and equilibrium modulus. An optimal bioink was designed using the DoE data to produce the greatest stiffness while still being pipettable. Three bioinks, one with the DoE-designed maximal stiffness, one with the experimentally defined maximal stiffness, and a literature-based control, were then printed using a 3D bioprinter and assessed for print fidelity. The resulting hydrogels were combined with human bone-marrow-derived mesenchymal stromal cells (hMSCs) and evaluated for cell viability. Results: The DoE ANOVA analysis indicated that the augmented three-level factorial design model used was a good fit (p < 0.0001). Using the model, DoE correctly predicted that a composite hydrogel consisting of 12.3% GelMA, 15.7% HA, and 2% gelatin would produce the maximum equilibrium modulus while still being pipettable. The hydrogel with the most optimal print fidelity was 10% GelMA, 2% HA, and 5% gelatin. There were no significant differences in the cell viability within the hydrogels from day 2 to day 7 (p > 0.05). There was, however, a significantly lower cell viability in the gel composed of 12.3% GelMA, 15.7% HA, and 2% gelatin compared to the other gels with a lower HA concentration (p < 0.05), showing that a higher HA content or print pressure may be cytotoxic within hydrogels. Conclusions: Extrusion-based 3DBP offers significant advantages for bone–tissue implants due to its high customizability. This study demonstrates that it is possible to create printable bone-like grafts from GelMA and HA with an increased HA content, favorable mechanical properties (145 kPa), and a greater than 80% cell viability. Full article
(This article belongs to the Special Issue Recent Advances in the Field of Mechanical Metamaterials and Their Associated Applications and Fabrication Techniques)
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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 - 06 Mar 2024
Viewed by 525
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)
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0 pages, 1639 KiB  
Communication
Controllable Technology for Thermal Expansion Coefficient of Commercial Materials for Solid Oxide Electrolytic Cells
by Ya Sun, Dun Jin, Xi Zhang, Qing Shao, Chengzhi Guan, Ruizhu Li, Fupeng Cheng, Xiao Lin, Guoping Xiao and Jianqiang Wang
Materials 2024, 17(5), 1216; https://doi.org/10.3390/ma17051216 - 06 Mar 2024
Viewed by 574
Abstract
Solid oxide electrolysis cell (SOEC) industrialization has been developing for many years. Commercial materials such as 8 mol% Y2O3-stabilized zirconia (YSZ), Gd0.1Ce0.9O1.95 (GDC), La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF), [...] Read more.
Solid oxide electrolysis cell (SOEC) industrialization has been developing for many years. Commercial materials such as 8 mol% Y2O3-stabilized zirconia (YSZ), Gd0.1Ce0.9O1.95 (GDC), La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF), La0.6Sr0.4CoO3−δ (LSC), etc., have been used for many years, but the problem of mismatched thermal expansion coefficients of various materials between cells has not been fundamentally solved, which affects the lifetime of SOECs and restricts their industry development. Currently, various solutions have been reported, such as element doping, manufacturing defects, and introducing negative thermal expansion coefficient materials. To promote the development of the SOEC industry, a direct treatment method for commercial materials—quenching and doping—is reported to achieve the controllable preparation of the thermal expansion coefficient of commercial materials. The quenching process only involves the micro-treatment of raw materials and does not have any negative impact on preparation processes such as powder slurry and sintering. It is a simple, low-cost, and universal research strategy to achieve the controllable preparation of the thermal expansion coefficient of the commercial material La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) through a quenching process by doping elements and increasing oxygen vacancies in the material. Commercial LSCF materials are heated to 800 °C in a muffle furnace, quickly removed, and cooled and quenched in 3.4 mol/L of prepared Y(NO3)3. The thermal expansion coefficient of the treated material can be reduced to 13.6 × 10−6 K−1, and the blank sample is 14.1 × 10−6 K−1. In the future, it may be possible to use the quenching process to select appropriate doping elements in order to achieve similar thermal expansion coefficients in SOECs. Full article
(This article belongs to the Section Energy Materials)
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16 pages, 6462 KiB  
Article
Synergistic Effect of Carbon Micro/Nano-Fillers and Surface Patterning on the Superlubric Performance of 3D-Printed Structures
by Katerina Gkougkousi, Alexandros E. Karantzalis, Pantelis G. Nikolakopoulos and Konstantinos G. Dassios
Materials 2024, 17(5), 1215; https://doi.org/10.3390/ma17051215 - 06 Mar 2024
Viewed by 734
Abstract
Superlubricity, the tribological regime where the coefficient of friction between two sliding surfaces almost vanishes, is currently being investigated as a viable route towards the energy efficiency envisioned by major long-term strategies for a sustainable future. This current study provides new insights towards [...] Read more.
Superlubricity, the tribological regime where the coefficient of friction between two sliding surfaces almost vanishes, is currently being investigated as a viable route towards the energy efficiency envisioned by major long-term strategies for a sustainable future. This current study provides new insights towards the development of self-lubricating systems by material and topological design, systems which tend to exhibit near-superlubric tribological performance, by reporting the synergistic effect of selective surface patterning and presence of carbon micro/nano-fillers on the frictional coefficients of additively manufactured structures. Geometric and biomimetic surface patterns were prepared by fused deposition modelling (FDM), using printing filaments of a polymeric matrix infused with graphene nanoplatelets (GNPs) and carbon fibers (Cf). The calorimetric, spectroscopic, mechanical and optical microscopy characterization of the starting materials and as-printed structures provided fundamental insights for their tribological characterization under a ball-on-disk configuration. In geometrically patterned PLA-based structures, a graphene presence reduced the friction coefficient by ca. 8%, whereas PETG exhibited the lowest coefficients, in the vicinity of 0.1, indicating a high supelubric potential. Biomimetic patterns exhibited an inferior frictional response due to their topologically and tribologically anisotropy of the surfaces. Overall, a graphene presence in the starting materials demonstrated great potential for friction reduction, while PETG showed a tribological performance not only superior to PLA, but also compatible with superlubric performance. Methodological and technical challenges are discussed in the text. Full article
(This article belongs to the Special Issue Nanocomposite Based Materials for Various Applications)
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12 pages, 4516 KiB  
Article
Preparation of CS-LS/AgNPs Composites and Photocatalytic Degradation of Dyes
by Jiabao Wu, Xinpeng Chen, Aijing Li, Tieling Xing and Guoqiang Chen
Materials 2024, 17(5), 1214; https://doi.org/10.3390/ma17051214 - 06 Mar 2024
Viewed by 619
Abstract
Synthetic dyes are prone to water pollution during use, jeopardizing biodiversity and human health. This study aimed to investigate the adsorption and photocatalytic assist potential of sodium lignosulfonate (LS) in in situ reduced silver nanoparticles (AgNPs) and chitosan (CS)-loaded silver nanoparticles (CS-LS/AgNPs) as [...] Read more.
Synthetic dyes are prone to water pollution during use, jeopardizing biodiversity and human health. This study aimed to investigate the adsorption and photocatalytic assist potential of sodium lignosulfonate (LS) in in situ reduced silver nanoparticles (AgNPs) and chitosan (CS)-loaded silver nanoparticles (CS-LS/AgNPs) as adsorbents for Rhodamine B (RhB). The AgNPs were synthesized by doping LS on the surface of chitosan for modification. Fourier transform infrared (FT-IR) spectrometry, energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to confirm the synthesis of nanomaterials. The adsorption and photocatalytic removal experiments of RhB were carried out under optimal conditions (initial dye concentration of 20 mg/L, adsorbent dosage of 0.02 g, time of 60 min, and UV power of 250 W), and the kinetics of dye degradation was also investigated, which showed that the removal rate of RhB by AgNPs photocatalysis can reach 55%. The results indicated that LS was highly effective as a reducing agent for the large-scale production of metal nanoparticles and can be used for dye decolorization. This work provides a new catalyst for the effective removal of dye from wastewater, and can achieve high-value applications of chitosan and lignin. Full article
(This article belongs to the Special Issue Properties and Applications of Advanced Textile Materials)
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17 pages, 4395 KiB  
Article
Finite Element Analysis and Fatigue Test of INTEGRA Dental Implant System
by Rafał Zieliński, Sebastian Lipa, Martyna Piechaczek, Jerzy Sowiński, Agata Kołkowska and Wojciech Simka
Materials 2024, 17(5), 1213; https://doi.org/10.3390/ma17051213 - 06 Mar 2024
Cited by 1 | Viewed by 651
Abstract
The study involved numerical FEA (finite element analysis) of dental implants. Based on this, fatigue tests were conducted according to the PN-EN 14801 standard required for the certification of dental products. Thanks to the research methodology developed by the authors, it was possible [...] Read more.
The study involved numerical FEA (finite element analysis) of dental implants. Based on this, fatigue tests were conducted according to the PN-EN 14801 standard required for the certification of dental products. Thanks to the research methodology developed by the authors, it was possible to conduct a thorough analysis of the impact of external and internal factors such as material, geometry, loading, and assembly of the dental system on the achieved value of fatigue strength limit in the examined object. For this purpose, FEM studies were based on identifying potential sites of fatigue crack initiation in reference to the results of the test conducted on a real model. The actions described in the study helped in the final evaluation of the dental system design process named by the manufacturer as INTEGRA OPTIMA 3.35. The objective of the research was to identify potential sites for fatigue crack initiation in a selected dental system built on the INTEGRA OPTIMA 3.35 set. The material used in the research was titanium grade 4. A map of reduced von Mises stresses was used to search for potential fatigue crack areas. The research [loading] was conducted on two mutually perpendicular planes positioned in such a way that the edge intersecting the planes coincided with the axis of the system. The research indicated that the connecting screw showed the least sensitivity (stress change) to the change in the loading plane, while the value of preload has a significant impact on the achieved fatigue strength of the system. In contrast, the endosteal implant (root) and the prosthetic connector showed the greatest sensitivity to the change in the loading plane. The method of mounting [securing] the endosteal implant using a holder, despite meeting the standards, may contribute to generating excessive stress concentration in the threaded part. Observation of the prosthetic connector in the Optima 3.35 system, cyclically loaded with a force of F ≈ 300 N in the area of the upper hexagonal peg, revealed a fatigue fracture. The observed change in stress peak in the dental connector for two different force application surfaces shows that the positioning of the dental system (setting of the socket in relation to the force action plane) is significantly decisive in estimating the limited fatigue strength. Full article
(This article belongs to the Special Issue State-of-the-Art Biomaterials Science and Bioengineering in Poland)
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14 pages, 1560 KiB  
Article
Biocomposites Based on Wheat Flour with Urea-Based Eutectic Plasticizer and Spent Coffee Grounds: Preparation, Physicochemical Characterization, and Study of Their Influence on Plant Growth
by Magdalena Zdanowicz, Marta Rokosa, Magdalena Pieczykolan, Adrian Krzysztof Antosik and Katarzyna Skórczewska
Materials 2024, 17(5), 1212; https://doi.org/10.3390/ma17051212 - 06 Mar 2024
Viewed by 636
Abstract
In this study, we conducted the first plasticization of wheat flour (WF) with the addition of choline chloride:urea (1:5 molar ratio) eutectic mixture as a plasticizer and spent coffee grounds (cf) as a filler. Thermoplastic wheat flour (TPWF) films were obtained via twin-screw [...] Read more.
In this study, we conducted the first plasticization of wheat flour (WF) with the addition of choline chloride:urea (1:5 molar ratio) eutectic mixture as a plasticizer and spent coffee grounds (cf) as a filler. Thermoplastic wheat flour (TPWF) films were obtained via twin-screw extrusion and then thermocompression. Their physicochemical characterization included mechanical tests, dynamic mechanical thermal analysis (DMTA), and sorption tests. XRD analysis revealed that the eutectic plasticizer led to a high degree of WF amorphization, which affected the physicochemical properties of TPWF. The results indicated that it was easy for the TPWF biocomposites to undergo thermocompression even with a high amount of the filler (20 pph per flour). The addition of the cf into TPWF led to an increase in tensile strength and a decrease in the swelling degree of the biocomposites. Biodegradation tests in soil revealed that the materials wholly degraded within 11 weeks. Moreover, a study of cultivated plants indicated that the biocomposites did not exhibit a toxic influence on the model rowing plant. Full article
(This article belongs to the Special Issue Food Industry Wastes and By-Products in Polymer Technology)
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13 pages, 3425 KiB  
Article
Design of an Optical Device Based on Kirigami Approach
by Marta De Giorgi
Materials 2024, 17(5), 1211; https://doi.org/10.3390/ma17051211 - 06 Mar 2024
Viewed by 449
Abstract
The aim of this work was to design a kirigami-based metamaterial with optical properties. This idea came from the necessity of a study that can improve common camouflage techniques to yield a product that is cheap, light, and easy to manufacture and assemble. [...] Read more.
The aim of this work was to design a kirigami-based metamaterial with optical properties. This idea came from the necessity of a study that can improve common camouflage techniques to yield a product that is cheap, light, and easy to manufacture and assemble. The author investigated the possibility of exploiting a rotation to achieve transparency and color changing. One of the most important examples of a kirigami structure is a geometry based on rotating squares, which is a one-degree-of-freedom mechanism. In this study, light polarization and birefringence were exploited to obtain transparency and color-changing properties using two polarizers and common cellophane tape. These elements were assembled with a rotating-square structure that allowed the rotation of a polarizer placed on the structure with respect to a fixed polarizer equipped with cellophane layers. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Advanced Materials Characterization)
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12 pages, 5207 KiB  
Article
Deformation Behavior of an Extruded 7075 Aluminum Alloy at Elevated Temperatures
by Tuo Ye, Erli Xia, Sawei Qiu, Jie Liu, Huanyu Yue, Jian Tang and Yuanzhi Wu
Materials 2024, 17(5), 1210; https://doi.org/10.3390/ma17051210 - 06 Mar 2024
Viewed by 560
Abstract
Hot compression tests were conducted to explore the deformation behavior of an extruded 7075 aluminum alloy bar at elevated temperatures. Specimens with 0°, 45°, and 90° angles along the extrusion direction were prepared. The compression temperatures were 300 and 400 °C, and the [...] Read more.
Hot compression tests were conducted to explore the deformation behavior of an extruded 7075 aluminum alloy bar at elevated temperatures. Specimens with 0°, 45°, and 90° angles along the extrusion direction were prepared. The compression temperatures were 300 and 400 °C, and the strain rates ranged from 0.001 to 0.1 s−1. The corresponding microstructures were characterized via OM and TEM, and the macroscopic texture was tested using XRD. The results indicated that the strength of the 7075 alloy decreases with higher compression temperatures and is in a proportional relationship with respect to the strain rate. During high-temperature compression, it is easier to stimulate atomic diffusion in the matrix, which can improve thermal activation abilities and facilitate dynamic recovery and dynamic recrystallization. In addition, the coarsening of precipitates also contributed to dynamic softening. When compressed at 300 °C, the stress levels of the 0° specimens ranked first, and those for the 45° specimens were the lowest. When compressed at 400 °C, the flow stresses of the specimens along three directions were comparable. The anisotropic mechanical behavior can be explained by the fiber grains and brass {011} <211> texture component. However, higher temperature deformation leads to recrystallization, which can weaken the anisotropy of mechanical properties. Full article
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14 pages, 4205 KiB  
Article
In Situ Preparation of rGO-Cement Using Thermal Reduction Method and Performance Study
by Jie Yao, Ao Guan, Wenqiang Ruan and Ying Ma
Materials 2024, 17(5), 1209; https://doi.org/10.3390/ma17051209 - 06 Mar 2024
Viewed by 674
Abstract
In this study, the combination of freeze-drying and high-temperature thermal reduction methods was employed to in situ prepare reduced graphene oxide (rGO)-Cement based on graphene oxide (GO)-Cement. The electrical conductivity and mechanical properties of the rGO-Cement were investigated. Microscopic analysis methods such as [...] Read more.
In this study, the combination of freeze-drying and high-temperature thermal reduction methods was employed to in situ prepare reduced graphene oxide (rGO)-Cement based on graphene oxide (GO)-Cement. The electrical conductivity and mechanical properties of the rGO-Cement were investigated. Microscopic analysis methods such as Raman spectra, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to confirm the successful transformation of GO-Cement to rGO-Cement. The research results demonstrated that with an increase in rGO content, the electrical resistivity of the rGO-Cement decreased first and then increased, reaching a percolation threshold at the dosage of 0.7 wt.%. The compressive strength and flexural strength of the rGO-Cement increased first and then decreased. The optimal dosage of rGO was 0.7%. The in situ preparation of rGO-Cement using the thermal reduction method holds a great potential for various applications, providing new ideas and methods for the modification and enhancement of cement materials. Full article
(This article belongs to the Section Carbon Materials)
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26 pages, 5515 KiB  
Article
Marble Powder as a Soil Stabilizer: An Experimental Investigation of the Geotechnical Properties and Unconfined Compressive Strength Analysis
by Ibrahim Haruna Umar and Hang Lin
Materials 2024, 17(5), 1208; https://doi.org/10.3390/ma17051208 - 05 Mar 2024
Cited by 2 | Viewed by 798
Abstract
Fine-grained soils present engineering challenges. Stabilization with marble powder has shown promise for improving engineering properties. Understanding the temporal evolution of Unconfined Compressive Strength (UCS) and geotechnical properties in stabilized soils could aid strength assessment. This study investigates the stabilization of fine-grained clayey [...] Read more.
Fine-grained soils present engineering challenges. Stabilization with marble powder has shown promise for improving engineering properties. Understanding the temporal evolution of Unconfined Compressive Strength (UCS) and geotechnical properties in stabilized soils could aid strength assessment. This study investigates the stabilization of fine-grained clayey soils using waste marble powder as an alternative binder. Laboratory experiments were conducted to evaluate the geotechnical properties of soil–marble powder mixtures, including Atterberg’s limits, compaction characteristics, California Bearing Ratio (CBR), Indirect Tensile Strength (ITS), and Unconfined Compressive Strength (UCS). The effects of various factors, such as curing time, molding water content, and composition ratios, on UCS, were analyzed using Exploratory Data Analysis (EDA) techniques, including histograms, box plots, and statistical modeling. The results show that the CBR increased from 10.43 to 22.94% for unsoaked and 4.68 to 12.46% for soaked conditions with 60% marble powder, ITS rose from 100 to 208 kN/m2 with 60–75% marble powder, and UCS rose from 170 to 661 kN/m2 after 28 days of curing, molding water content (optimum at 22.5%), and composition ratios (optimum at 60% marble powder). Complex modeling yielded R2 (0.954) and RMSE (29.82 kN/m2) between predicted and experimental values. This study demonstrates the potential of utilizing waste marble powder as a sustainable and cost-effective binder for soil stabilization, transforming weak soils into viable construction materials. Full article
(This article belongs to the Special Issue Reliability Modeling of Complex Systems in Materials and Devices)
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20 pages, 35324 KiB  
Article
A Stochastic Dynamics Method for Time-Varying Damping Depending on Temperature/Frequency for Several Alloy Materials
by Wenjun Huang, Guorui Yu, Wentao Xu and Ruchuan Zhou
Materials 2024, 17(5), 1207; https://doi.org/10.3390/ma17051207 - 05 Mar 2024
Viewed by 490
Abstract
In the field of aerospace and advanced equipment manufacturing, accurate response analysis has been paid more attention, requiring a more comprehensive study of the variation of mechanical parameters with the service environment. The damping variation characteristics of 304 aluminum alloy, Sa564 high-strength alloy, [...] Read more.
In the field of aerospace and advanced equipment manufacturing, accurate response analysis has been paid more attention, requiring a more comprehensive study of the variation of mechanical parameters with the service environment. The damping variation characteristics of 304 aluminum alloy, Sa564 high-strength alloy, GW63K magnesium alloy, and Q235 steel were investigated in this paper, which plays a significant role in the dynamic responses of structures. Variable damping ratios were revealed by the damping tests based on a dynamic mechanical analysis (DMA). The numerical method of temperature/frequency-dependent damping parameters in stochastic dynamics was focused on. With a large variation in the damping ratio, a numerical constitutive relation for temperature-dependent damping was proposed, and an efficient stochastic dynamics method was derived to analyze the responses of structures based on the pseudo excitation method (PEM) and variable damping theory. The computational accuracy and validity of the proposed method are confirmed during the vibration tests and numerical analysis. Based on the comparison results of the two damping models and the experiments on GW63K alloy, we proved that the proposed method is more accurate to the real response of the actual engineering structure. The differences in dynamic responses between the constant damping and experiments are significant, and more attention should be paid to the numerical method of stochastic dynamic response of variable damping materials in the aviation and aerospace fields and high-temperature environments. Full article
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11 pages, 2344 KiB  
Article
C60- and CdS-Co-Modified Nano-Titanium Dioxide for Highly Efficient Photocatalysis and Hydrogen Production
by Meifang Zhang, Xiangfei Liang, Yang Gao and Yi Liu
Materials 2024, 17(5), 1206; https://doi.org/10.3390/ma17051206 - 05 Mar 2024
Viewed by 657
Abstract
The inherent properties of TiO2, including a wide band gap and restricted spectral response range, hinder its commercial application and its ability to harness only 2–3% of solar energy. To address these challenges and unlock TiO2’s full potential in [...] Read more.
The inherent properties of TiO2, including a wide band gap and restricted spectral response range, hinder its commercial application and its ability to harness only 2–3% of solar energy. To address these challenges and unlock TiO2’s full potential in photocatalysis, C60- and CdS-co-modified nano-titanium dioxide has been adopted in this work to reduce the band gap, extend the absorption wavelength, and control photogenerated carrier recombination, thereby enhancing TiO2’s light-energy-harnessing capabilities and hydrogen evolution capacity. Using the sol-gel method, we successfully synthesized CdS-C60/TiO2 composite nanomaterials, harnessing the unique strengths of CdS and C60. The results showed a remarkable average yield of 34.025 μmol/h for TiO2 co-modified with CdS and C60, representing a substantial 17-fold increase compared to pure CdS. Simultaneously, the average hydrogen generation of C60-modified CdS surged to 5.648 μmol/h, a notable two-fold improvement over pure CdS. This work opens up a new avenue for the substantial improvement of both the photocatalytic degradation efficiency and hydrogen evolution capacity, offering promise of a brighter future in photocatalysis research. Full article
(This article belongs to the Special Issue Novel Nanomaterials for Energy Storage and Catalysis)
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18 pages, 3586 KiB  
Article
The Impact of Marangoni and Buoyancy Convections on Flow and Segregation Patterns during the Solidification of Fe-0.82wt%C Steel
by Ibrahim Sari, Menghuai Wu, Mahmoud Ahmadein, Sabbah Ataya, Nashmi Alrasheedi and Abdellah Kharicha
Materials 2024, 17(5), 1205; https://doi.org/10.3390/ma17051205 - 05 Mar 2024
Viewed by 586
Abstract
Due to the high computational costs of the Eulerian multiphase model, which solves the conservation equations for each considered phase, a two-phase mixture model is proposed to reduce these costs in the current study. Only one single equation for each the momentum and [...] Read more.
Due to the high computational costs of the Eulerian multiphase model, which solves the conservation equations for each considered phase, a two-phase mixture model is proposed to reduce these costs in the current study. Only one single equation for each the momentum and enthalpy equations has to be solved for the mixture phase. The Navier–Stokes and energy equations were solved using the 3D finite volume method. The model was used to simulate the liquid–solid phase transformation of a Fe-0.82wt%C steel alloy under the effect of both thermocapillary and buoyancy convections. The alloy was cooled in a rectangular ingot (100 × 100 × 10 mm3) from the bottom cold surface to the top hot free surface by applying a heat transfer coefficient of h = 600 W/m2/K, which allows for heat exchange with the outer medium. The purpose of this work is to study the effect of the surface tension on the flow and segregation patterns. The results before solidification show that Marangoni flow was formed at the free surface of the molten alloy, extending into the liquid depth and creating polygonized hexagonal patterns. The size and the number of these hexagons were found to be dependent on the Marangoni number, where the number of convective cells increases with the increase in the Marangoni number. During solidification, the solid front grew in a concave morphology, as the centers of the cells were hotter; a macro-segregation pattern with hexagonal cells was formed, which was analogous to the hexagonal flow cells generated by the Marangoni effect. After full solidification, the segregation was found to be in perfect hexagonal shapes with a strong compositional variation at the free surface. This study illuminates the crucial role of surface-tension-driven Marangoni flow in producing hexagonal patterns before and during the solidification process and provides valuable insights into the complex interplay between the Marangoni flow, buoyancy convection, and solidification phenomena. Full article
(This article belongs to the Special Issue Advances in Multicomponent Alloy Design, Simulation and Properties)
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21 pages, 4304 KiB  
Article
A 3D Meso-Scale Model and Numerical Uniaxial Compression Tests on Concrete with the Consideration of the Friction Effect
by Jiawei Wang, Xinlu Yu, Yingqian Fu and Gangyi Zhou
Materials 2024, 17(5), 1204; https://doi.org/10.3390/ma17051204 - 05 Mar 2024
Viewed by 566
Abstract
Achieving the real mechanical performance of construction materials is significantly important for the design and engineering of structures. However, previous researchers have shown that contact friction performs an important role in the results of uniaxial compression tests. Strong discreteness generally appears in concrete-like [...] Read more.
Achieving the real mechanical performance of construction materials is significantly important for the design and engineering of structures. However, previous researchers have shown that contact friction performs an important role in the results of uniaxial compression tests. Strong discreteness generally appears in concrete-like construction materials due to the random distribution of the components. A numerical meso-scale finite-element (FE) method provides the possibility of generating an ideal material with the same component percentages and distribution. Thus, a well-designed meso-FE model was employed to investigate the effect of friction on the mechanical behavior and failure characteristics of concrete under uniaxial compression loading. The results showed that the mechanical behavior and failure profiles of the simulation matched well with the experimental results. Based on this model, the effect of friction was determined by changing the contact friction coefficient from 0.0 to 0.7. It was found that frictional contact had a slight influence on the elastic compressive mechanical behavior of concrete. However, the nonlinear hardening behavior of the stress–strain curves showed a fairly strong relationship with the frictional contact. The final failure profiles of the experiments showed a “sand-glass” shape that might be expected to result from the contact friction. Thus, the numerical meso-scale FE model showed that contact friction had a significant influence on both the mechanical performance and the failure profiles of concrete. Full article
(This article belongs to the Special Issue Multiscale Modeling and Simulation of Cementitious Materials Behavior)
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20 pages, 18651 KiB  
Article
The Influence of Flame Exposure and Solid Particle Erosion on Tensile Strength of CFRP Substrate with Manufactured Protective Coating
by Przemysław Golewski and Michał Budka
Materials 2024, 17(5), 1203; https://doi.org/10.3390/ma17051203 - 05 Mar 2024
Viewed by 641
Abstract
This paper presents the results of laboratory tests for new materials made of a carbon fibre-reinforced polymer (CFRP) composite with a single-sided protective coating. The protective coatings were made of five different powders—Al2O3, aluminium, quartz sand, crystalline silica and [...] Read more.
This paper presents the results of laboratory tests for new materials made of a carbon fibre-reinforced polymer (CFRP) composite with a single-sided protective coating. The protective coatings were made of five different powders—Al2O3, aluminium, quartz sand, crystalline silica and copper—laminated in a single process during curing of the prepreg substrate with an epoxy matrix. The specimens were subjected to flame exposure and solid particle erosion tests, followed by uniaxial tensile tests. A digital image correlation (DIC) system was used to observe the damage location and deformation of the specimens. All coatings subjected to solid particle erosion allowed an increase in tensile failure force ranging from 5% to 31% compared to reference specimens made of purely CFRP. When exposed to flame, only three of the five materials tested, Al2O3, aluminium, quartz sand, could be used to protect the surface, which allowed an increase in tensile failure force of 5.6%. Full article
(This article belongs to the Topic Advanced Manufacturing and Surface Technology)
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19 pages, 6604 KiB  
Article
The Potential of 3D Printing in Thermal Insulating Composite Materials—Experimental Determination of the Impact of the Geometry on Thermal Resistance
by Beata Anwajler, Jerzy Szołomicki, Paweł Noszczyk and Michał Baryś
Materials 2024, 17(5), 1202; https://doi.org/10.3390/ma17051202 - 05 Mar 2024
Viewed by 824
Abstract
This paper focuses on the analysis of the thermal properties of prototype insulation structures produced using SLS and SLA additive technologies. There is a noticeable lack of analysis in the scientific literature regarding the geometry of 3D-printed structures in terms of their thermal [...] Read more.
This paper focuses on the analysis of the thermal properties of prototype insulation structures produced using SLS and SLA additive technologies. There is a noticeable lack of analysis in the scientific literature regarding the geometry of 3D-printed structures in terms of their thermal properties. The aim of this paper was to analyze printed samples of prototype thermal insulation composite structures and their potential for use in building applications. The research material consisted of closed and open cell foams of varying structural complexity. Increasing the complexity of the composite core structure resulted in a statistically significant decrease in the value of the thermal conductivity coefficient λ and the heat transfer coefficient U, and an increase in the thermal resistance Rc. The experimental results showed that the geometric structure of the air voids in the material is a key factor in regulating heat transfer. The control of porosity in materials produced by additive technology can be an effective tool for designing structures with high insulation efficiency. The best performance of the prototype materials produced by the SLS method was a three-layer cellular composite with a gyroid core structure. It was also shown that the four-layer gyroid structure panels with an outer layer of metallized polyethylene film produced using 3D SLA printing had the best thermal insulation. As a result, the analysis confirmed the possibility of producing energy-efficient insulation materials using 3D printing. These materials can be used successfully in construction and other industries. Further research will significantly improve the quality, accuracy, and speed of printing insulation materials, reduce the negative impact on the natural environment, and develop intelligent adaptive solutions. Full article
(This article belongs to the Special Issue Advances in Functional Polymers and Composite for 3D Manufacturing, Insulations and Energy Storage)
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19 pages, 46658 KiB  
Article
Comparison of the Field Trapping Ability of MgB2 and Hybrid Disc-Shaped Layouts
by Michela Fracasso, Roberto Gerbaldo, Gianluca Ghigo, Daniele Torsello, Yiteng Xing, Pierre Bernstein, Jacques Noudem and Laura Gozzelino
Materials 2024, 17(5), 1201; https://doi.org/10.3390/ma17051201 - 05 Mar 2024
Viewed by 604
Abstract
Superconductors have revolutionized magnet technology, surpassing the limitations of traditional coils and permanent magnets. This work experimentally investigates the field-trapping ability of a MgB2 disc at various temperatures and proposes new hybrid (MgB2-soft iron) configurations using a numerical approach based [...] Read more.
Superconductors have revolutionized magnet technology, surpassing the limitations of traditional coils and permanent magnets. This work experimentally investigates the field-trapping ability of a MgB2 disc at various temperatures and proposes new hybrid (MgB2-soft iron) configurations using a numerical approach based on the vector potential (A→) formulation. The experimental characterization consists in measurements of trapped magnetic flux density carried out using cryogenic Hall probes located at different radial positions over the MgB2 sample, after a field cooling (FC) process and the subsequent removal of the applied field. Measurements were performed also as a function of the distance from the disc surface. The numerical modelling of the superconductor required the evaluation of the critical current density dependence on the magnetic flux density (Jc(B)) obtained through an iterative procedure whose output were successfully validated by the comparison between experimental and computed data. The numerical model, upgraded to also describe the in-field behavior of ARMCO soft iron, was then employed to predict the field-trapping ability of hybrid layouts of different shapes. The most promising results were achieved by assuming a hollow superconducting disc filled with a ferromagnetic (FM) cylinder. With such a geometry, optimizing the radius of the FM cylinder while the external dimensions of the superconducting disc are kept unchanged, an improvement of more than 30% is predicted with respect to the full superconducting disc, assuming a working temperature of 20 K. Full article
(This article belongs to the Special Issue Novel Superconducting Materials and Applications of Superconductivity)
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13 pages, 10214 KiB  
Article
Influences of Composite Electrodeposition Parameters on the Properties of Ni-Doped Co-Mn Composite Spinel Coatings
by Wei Tong, Weiqiang Wang, Xiayu Leng and Jianli Song
Materials 2024, 17(5), 1200; https://doi.org/10.3390/ma17051200 - 05 Mar 2024
Viewed by 502
Abstract
To enhance the comprehensive performance of solid oxide fuel cells (SOFCs) ferritic stainless steel (FSS) interconnectors, a novel approach involving composite electrodeposition and thermal conversion is proposed to prepare Ni-doped Co-Mn composite spinel protective coatings on FSS surfaces. The process involves the composite [...] Read more.
To enhance the comprehensive performance of solid oxide fuel cells (SOFCs) ferritic stainless steel (FSS) interconnectors, a novel approach involving composite electrodeposition and thermal conversion is proposed to prepare Ni-doped Co-Mn composite spinel protective coatings on FSS surfaces. The process involves the composite electrodeposition of a Ni-doped Co-Mn precursor coating, followed by thermal conversion to obtain the Co-Mn-Ni composite spinel coating. Crofer 22H was used as the substrate and orthogonal experiments were designed to investigate the influences of deposition solution pH, stirring rate, cathode current density, and the element content of Mn and Ni on the surface morphology and properties of the composite coatings, respectively. The characterization of the prepared coatings was conducted through macroscopic and microscopic morphology observations of the component surface, energy dispersive spectroscopy (EDS) analysis, and area specific resistance (ASR) testing, etc. Finally, the optimized composite electrodeposition parameters and the Mn-Ni content ratio in the solution were obtained. Experimental results indicated that the composite spinel coating prepared with the optimized process parameters exhibited excellent adhesion to the substrate, and the diffusion and migration of Cr element has been effectively inhibited. Compared with the substrate, the ASR of the coated components has also been decreased simultaneously, which provided an effective method for the surface modification of SOFC FSS interconnectors. Full article
(This article belongs to the Section Advanced Composites)
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22 pages, 25261 KiB  
Article
Simulation Study on Temperature and Stress Fields in Mg-Gd-Y-Zn-Zr Alloy during CMT Additive Manufacturing Process
by Mingkun Zhao, Zhanyong Zhao, Wenbo Du, Peikang Bai and Zhiquan Huang
Materials 2024, 17(5), 1199; https://doi.org/10.3390/ma17051199 - 05 Mar 2024
Viewed by 669
Abstract
A new heat source combination, consisting of a uniform body heat source and a tilted double ellipsoidal heat source, has been developed for cold metal transfer (CMT) wire-arc additive manufacturing of Mg-Gd-Y-Zn-Zr alloy. Simulations were conducted to analyze the temperature field and stress [...] Read more.
A new heat source combination, consisting of a uniform body heat source and a tilted double ellipsoidal heat source, has been developed for cold metal transfer (CMT) wire-arc additive manufacturing of Mg-Gd-Y-Zn-Zr alloy. Simulations were conducted to analyze the temperature field and stress distribution during the process. The optimal combination of feeding speed and welding speed was found to be 8 m/min and 8 mm/s, respectively, resulting in the lowest thermal accumulation and residual stress. Z-axis residual stress was identified as the main component of residual stress. Electron Backscatter Diffraction (EBSD) testing showed weak texture strength, and Kernel Average Misorientation (KAM) analysis revealed that the 1st layer had the highest residual stress, while the 11th layer had higher residual stress than the 6th layer. Microhardness in the 1st, 11th, and 6th layers varies due to residual stress impacts on dislocation density. Higher residual stress increases dislocation density, raising microhardness in components. The experimental results were highly consistent with the simulated results. Full article
(This article belongs to the Special Issue Additive Manufacturing and Microstructure Characteristics of Metallic Material)
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12 pages, 3631 KiB  
Article
Effect of Tungsten Inert Gas Remelting on Microstructure and Corrosion Resistance of Q450NQR1 High-Strength Weathering Steel-Welded Joints
by Xuemei Li, Yang Liu, Rui Guo, Zicheng Li, Qingming Hu, Meng Liu, Lei Zhu and Xiangxia Kong
Materials 2024, 17(5), 1198; https://doi.org/10.3390/ma17051198 - 04 Mar 2024
Viewed by 629
Abstract
In this paper, the corrosion environment of a railway coal truck was simulated with 1.0%H2SO4 + 3%NaCl solution. The effect of weld toe Tungsten Inert Gas (TIG) remelting on the microstructure and corrosion resistance of welded joints of Q450NQR1 high-strength [...] Read more.
In this paper, the corrosion environment of a railway coal truck was simulated with 1.0%H2SO4 + 3%NaCl solution. The effect of weld toe Tungsten Inert Gas (TIG) remelting on the microstructure and corrosion resistance of welded joints of Q450NQR1 high-strength weathering steel was studied. The results show that the weld toe melts to form a remelting area after TIG remelting. After TIG remelting, the weld geometry was improved, and the stress concentration factor decreased from 1.17 to 1.06 at the weld toe, a decrease of 9.4%. TIG remelting refines the microstructure of the weld toe and improves the corrosion resistance of the welded joint. The surface of the TIG-remelted sample is uniformly corroded with no “deep and narrow” pits after the removal of corrosion products. The weight loss rate and corrosion rate of remelted welds are lower than those of unremelted welds. The structure of corrosion products is loose at the initial stage of corrosion, and the corrosion products are transformed into Fe3O4 and Fe2O3 protective rust layers with a dense structure after 480 h of corrosion. With the extension of corrosion time, the tensile strength and percentage elongation of the specimen decreased linearly. The decreasing rates of tensile strength of remelted and unremelted specimens were 0.09 and 0.11, respectively, and the decreasing rates of elongation after fracture were 0.0061 and 0.0076, respectively. Full article
(This article belongs to the Section Corrosion)
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56 pages, 21190 KiB  
Review
An In-Depth Exploration of Unconventional Machining Techniques for INCONEL® Alloys
by André F. V. Pedroso, Naiara P. V. Sebbe, Francisco J. G. Silva, Raul D. S. G. Campilho, Rita C. M. Sales-Contini, Rui P. Martinho and Rafaela B. Casais
Materials 2024, 17(5), 1197; https://doi.org/10.3390/ma17051197 - 04 Mar 2024
Cited by 1 | Viewed by 854
Abstract
Build-up-edge (BUE), high-temperature machining and tool wear (TW) are some of the problems associated with difficult-to-machine materials for high-temperature applications, contributing significantly to high-cost manufacturing and poor tool life (TL) management. A detailed review of non-traditional machining processes that ease the machinability of [...] Read more.
Build-up-edge (BUE), high-temperature machining and tool wear (TW) are some of the problems associated with difficult-to-machine materials for high-temperature applications, contributing significantly to high-cost manufacturing and poor tool life (TL) management. A detailed review of non-traditional machining processes that ease the machinability of INCONEL®, decrease manufacturing costs and suppress assembly complications is thus of paramount significance. Progress taken within the field of INCONEL® non-conventional processes from 2016 to 2023, the most recent solutions found in the industry, and the prospects from researchers have been analysed and presented. In ensuing research, it was quickly noticeable that some techniques are yet to be intensely exploited. Non-conventional INCONEL® machining processes have characteristics that can effectively increase the mechanical properties of the produced components without tool-workpiece contact, posing significant advantages over traditional manufacturing. Full article
(This article belongs to the Special Issue Tools for Machining and Forming: Novel Materials and Wear Behaviour)
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28 pages, 9843 KiB  
Review
Photonic Crystal Structures for Photovoltaic Applications
by Anna Starczewska and Mirosława Kępińska
Materials 2024, 17(5), 1196; https://doi.org/10.3390/ma17051196 - 04 Mar 2024
Viewed by 983
Abstract
Photonic crystals are artificial structures with a spatial periodicity of dielectric permittivity on the wavelength scale. This feature results in a spectral region over which no light can propagate within such a material, known as the photonic band gap (PBG). It leads to [...] Read more.
Photonic crystals are artificial structures with a spatial periodicity of dielectric permittivity on the wavelength scale. This feature results in a spectral region over which no light can propagate within such a material, known as the photonic band gap (PBG). It leads to a unique interaction between light and matter. A photonic crystal can redirect, concentrate, or even trap incident light. Different materials (dielectrics, semiconductors, metals, polymers, etc.) and 1D, 2D, and 3D architectures (layers, inverse opal, woodpile, etc.) of photonic crystals enable great flexibility in designing the optical response of the material. This opens an extensive range of applications, including photovoltaics. Photonic crystals can be used as anti-reflective and light-trapping surfaces, back reflectors, spectrum splitters, absorption enhancers, radiation coolers, or electron transport layers. This paper presents an overview of the developments and trends in designing photonic structures for different photovoltaic applications. Full article
(This article belongs to the Special Issue Advances in Photoelectric Materials: Preparation, Properties, and Applications)
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