Materials

41 pages, 7570 KiB

Open AccessReview

Structure and Properties of Al–CNT-Based Composites Manufactured by Different Methods: A Brief Review

by Marat Nurguzhin, Marat Janikeyev, Myrzakhan Omarbayev, Azira Yermakhanova, Mohammed Meiirbekov, Miras Zhumakhanov, Aruzhan Keneshbekova, Meiram Atamanov, Aigerim Akylbayeva, Aidos Lesbayev and Darkhan Yerezhep

Materials 2025, 18(1), 214; https://doi.org/10.3390/ma18010214 - 6 Jan 2025

Viewed by 750

Abstract

Aluminum–carbon nanotube (Al–CNT) composites represent a cutting-edge class of materials characterized by their exceptional mechanical, thermal, and electrical properties, making them highly promising for aerospace, automotive, electronics, and energy applications. This review systematically examines the impact of various fabrication methods, including conventional powder [...] Read more.

Aluminum–carbon nanotube (Al–CNT) composites represent a cutting-edge class of materials characterized by their exceptional mechanical, thermal, and electrical properties, making them highly promising for aerospace, automotive, electronics, and energy applications. This review systematically examines the impact of various fabrication methods, including conventional powder metallurgy, diffusion and reaction coupling, as well as adhesive and reaction bonding on the microstructure and performance of Al–CNT composites. The analysis emphasizes the critical role of CNT dispersion, interfacial bonding, and the formation of reinforcing phases, such as Al₄C₃ and Al₂O₃, in determining the mechanical strength, wear resistance, corrosion resistance, and thermal stability of these materials. The challenges of CNT agglomeration, high production costs, and difficulties in controlling interfacial interactions are highlighted alongside potential solutions, such as surface modifications and reinforcement strategies. The insights presented aim to guide future research and innovation in this rapidly evolving field. Full article

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40 pages, 12985 KiB

Open AccessArticle

Electrolytic Ni-P and Ni-P-Cu Coatings on PCM-Loaded Expanded Graphite for Enhanced Battery Thermal Management with Mechanical Properties

by Onur Güler and Mustafa Yusuf Yazıcı

Materials 2025, 18(1), 213; https://doi.org/10.3390/ma18010213 - 6 Jan 2025

Viewed by 491

Abstract

This study addresses the thermal management challenge in battery systems by enhancing phase change material composites with Ni-P and Ni-P-Cu coatings on phase change material/expanded graphite structures. Traditional phase change materials are limited by low thermal conductivity and mechanical stability, which restricts their [...] Read more.

This study addresses the thermal management challenge in battery systems by enhancing phase change material composites with Ni-P and Ni-P-Cu coatings on phase change material/expanded graphite structures. Traditional phase change materials are limited by low thermal conductivity and mechanical stability, which restricts their effectiveness in high-demand applications. Unlike previous studies, this work integrates Ni-P and Ni-P-Cu coatings to significantly improve both the thermal conductivity and mechanical strength of phase change material/expanded graphite composites, filling a crucial gap in battery thermal management solutions. The results reveal that Ni-P-Cu-coated phase change material/expanded graphite composites exhibit a superior thermal conductivity of 27.1 W/m·K, significantly outperforming both uncoated and Ni-P-coated counterparts. Mechanical testing showed that the Ni-P-Cu coating provided the highest compressive strength at 39.4 MPa and enhanced tensile strength due to the coating’s highly crystalline structure and smaller grain size. Additionally, the phase-change characteristics of the phase change material/expanded graphite composites, with phase transition temperatures between 38 °C and 43 °C, allowed effective heat absorption, stabilizing battery temperatures under 1.25C and 2.5C discharge rates. Voltage decay analysis indicated that Ni-P and Ni-P-Cu coatings reduced polarization effects, extending operational stability. These findings suggest that Ni-P-Cu-coated phase change material/expanded graphite composites are highly effective in thermal management applications, especially in battery systems where efficient heat dissipation and mechanical durability are critical for performance and safety. This study offers a promising approach to improving energy storage systems for applications such as electric vehicles, grid storage, and portable electronics. Full article

(This article belongs to the Section Energy Materials)

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15 pages, 5922 KiB

Open AccessArticle

Comparative Study on the Calcium Leaching Resistance of Low-Heat Cement, Moderate-Heat Cement, and Ordinary Portland Cement Pastes

by Chunmeng Jiang, Shihao An, Shuangxi Li, Yingjie Chen and Jian Liu

Materials 2025, 18(1), 212; https://doi.org/10.3390/ma18010212 - 6 Jan 2025

Viewed by 487

Abstract

Hydraulic structures are frequently subjected to soft-water or acidic environments, necessitating serious consideration of the long-term effects of calcium leaching on the durability of concrete structures. Three types of common Portland cement (ordinary Portland cement, moderate-heat cement, and low-heat cement) paste samples widely [...] Read more.

Hydraulic structures are frequently subjected to soft-water or acidic environments, necessitating serious consideration of the long-term effects of calcium leaching on the durability of concrete structures. Three types of common Portland cement (ordinary Portland cement, moderate-heat cement, and low-heat cement) paste samples widely applied to hydraulic concrete were immersed in a 6 mol/L NH₄Cl solution to simulate accelerated calcium leaching behavior. The mass loss, porosity, leaching depth, compressive strength, and Ca/Si ratio of the three types of pastes were measured at different immersion stages (0, 14, 28, 56, 91, 140, and 180 days). The Vickers hardness index was employed to compare cement samples subjected to erosion for 30 and 180 days. The microstructure and composition of the mineralogical phases of the leached samples were also determined by X-ray diffraction, thermogravimetric analysis, and scanning electronic microscopy. Accordingly, the time-varying behavior and deterioration mechanism of the different cements subjected to leaching were contrastively revealed. The results showed that the calcium leaching resistance of the low-heat cement was the best, followed by the moderate-heat cement and ordinary Portland cement, proving that the content and structure of Ca(OH)₂ and C-S-H gels were closely related to the leaching performance of the cement. The less Ca(OH)₂ and more aggregated C-H-S gels produced by C₂S led to better calcium leaching resistance in the cement. Therefore, the leaching performance of Portland cement could be effectively improved by reducing the content of C₃S and increasing the content of C₂S, and the dissolution rate of calcium ions under leaching could be reduced by controlling the low initial calcium content in cementitious materials. This paper offers theoretical guidance for mitigating the long-term effects of calcium leaching on hydraulic concrete structures by conducting a comprehensive comparative analysis of the damage behavior and deterioration mechanisms of various types of Portland cement under identical erosion conditions. Full article

(This article belongs to the Special Issue Sustainable and Advanced Cementitious Materials)

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21 pages, 19299 KiB

Open AccessArticle

Temperature Uniformity Control of 12-Inch Semiconductor Wafer Chuck Using Double-Wall TPMS in Additive Manufacturing

by Sohyun Park, Jaewook Lee, Seungyeop Lee, Jihyun Sung, Hyungug Jung, Ho Lee and Kunwoo Kim

Materials 2025, 18(1), 211; https://doi.org/10.3390/ma18010211 - 6 Jan 2025

Viewed by 587

Abstract

In semiconductor inspection equipment, a chuck used to hold a wafer is equipped with a cooling or heating system for temperature uniformity across the surface of the wafer. Surface temperature uniformity is important for increasing semiconductor inspection speed. Triply periodic minimal surfaces (TPMSs) [...] Read more.

In semiconductor inspection equipment, a chuck used to hold a wafer is equipped with a cooling or heating system for temperature uniformity across the surface of the wafer. Surface temperature uniformity is important for increasing semiconductor inspection speed. Triply periodic minimal surfaces (TPMSs) are proposed to enhance temperature uniformity. TPMSs are a topic of increasing research in the field of additive manufacturing and are a type of metamaterial inspired by nature. TPMSs are periodic surfaces with no intersections. Their continuous curve offers self-support during the additive manufacturing process. This structure enables the division of a single space into two domains. As a result, the heat transfer area per unit volume is larger than that of general lattice structures, leading to a superior heat transfer performance. This paper proposes a new structure called a double-wall TPMS. The process of creating a double-walled TPMS by adjusting the thickness of the sheet TPMS was investigated, and its thermal performance was studied. Finally, a double-wall TPMS was applied to the chuck. The optimal designs for the diamond and gyroid structures exhibited a difference in surface temperature uniformity of 0.23 °C and 0.66 °C, respectively. Accordingly, the models optimized with the double-wall TPMS are proposed. Full article

(This article belongs to the Special Issue Advanced Additive Manufacturing and Application)

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17 pages, 4411 KiB

Open AccessArticle

Study of Corrosion of Portland Cement Embedded Steel with Addition of Multi-Wall Carbon Nanotubes

by Miguel Angel Gómez-Aristizabal, Jhoan Mauricio Moreno-Vargas, Laura María Echeverry-Cardona and Elisabeth Restrepo-Parra

Materials 2025, 18(1), 210; https://doi.org/10.3390/ma18010210 - 6 Jan 2025

Viewed by 510

Abstract

In this study, we research the innovative application of multi-walled carbon nanotubes (MWCNTs) as corrosion inhibitors in Portland cement embedded steel. The physicochemical properties of the dispersion solutions were evaluated, varying the storage time, to analyze their effect on corrosion resistance. Using a [...] Read more.

In this study, we research the innovative application of multi-walled carbon nanotubes (MWCNTs) as corrosion inhibitors in Portland cement embedded steel. The physicochemical properties of the dispersion solutions were evaluated, varying the storage time, to analyze their effect on corrosion resistance. Using a dispersion energy of 440 J/g and a constant molarity of 10 mM, stable dispersions were achieved for up to 3 weeks. These dispersions were characterized using Raman spectroscopy, UV-Vis spectroscopy and Zeta potential spectroscopy to assess the stability and structural damage of the MWCNTs. These results show that the addition of MWCNTs not only reduces the porosity of the cement matrix, but also forms an effective barrier against chloride ion intrusion, protecting the reinforcing steel. This approach stands out for combining improved mechanical properties and significant corrosion resistance, representing a promising innovation in the development of more durable construction materials. Full article

(This article belongs to the Section Carbon Materials)

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12 pages, 8477 KiB

Open AccessArticle

Study on Water Damage of Asphalt–Aggregate Based on Molecular Dynamics

by Shenghao Wang, Yan Chen, Lihua Wang, Naixin Cui, Chunfeng Li and Shifu Sun

Materials 2025, 18(1), 209; https://doi.org/10.3390/ma18010209 - 6 Jan 2025

Viewed by 518

Abstract

To investigate the water damage at the interface between emulsified asphalt and aggregate under the action of external water infiltration, firstly, cetyltrimethylammonium bromide was used as an emulsifier to prepare emulsified asphalt in the laboratory, and its basic properties were tested. Then, based [...] Read more.

To investigate the water damage at the interface between emulsified asphalt and aggregate under the action of external water infiltration, firstly, cetyltrimethylammonium bromide was used as an emulsifier to prepare emulsified asphalt in the laboratory, and its basic properties were tested. Then, based on molecular dynamics, an emulsified asphalt–aggregate interface model with different water contents was constructed to calculate the adhesion work of the emulsified asphalt–aggregate interface. The results show that the simulated values of emulsified asphalt density, cohesive energy density, and solubility are in good agreement with the experimental values. Under the same water content, the adhesion force between asphalt and three oxides (CaO, Al₂O₃, SiO₂) is arranged in the following order: CaO > Al₂O₃ > SiO₂. The bonding performance of an alkaline aggregate to asphalt is better than that of an acid aggregate. The van der Waals force plays a major role in the adhesion performance of an emulsified asphalt mixture, and electrostatic force plays a secondary role. Under the action of external force, the macroscopic failure mode of the emulsified asphalt–aggregate is as follows: the alkaline oxide-emulsified asphalt system is cohesive failure; the acid and neutral oxide-emulsified asphalt system is adhesive failure; the enrichment of water molecules at the interface is the main factor causing water damage. Full article

(This article belongs to the Special Issue Advanced Road Materials and Pavement Engineering: Design, Structure, Performance and Characterization)

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12 pages, 3591 KiB

Open AccessArticle

Multilayer Graphene Stacked with Silver Nanowire Networks for Transparent Conductor

by Jinsung Kwak

Materials 2025, 18(1), 208; https://doi.org/10.3390/ma18010208 - 6 Jan 2025

Viewed by 457

Abstract

A mechanically robust flexible transparent conductor with high thermal and chemical stability was fabricated from welded silver nanowire networks (w-Ag-NWs) sandwiched between multilayer graphene (MLG) and polyimide (PI) films. By modifying the gas flow dynamics and surface chemistry of the Cu surface during [...] Read more.

A mechanically robust flexible transparent conductor with high thermal and chemical stability was fabricated from welded silver nanowire networks (w-Ag-NWs) sandwiched between multilayer graphene (MLG) and polyimide (PI) films. By modifying the gas flow dynamics and surface chemistry of the Cu surface during graphene growth, a highly crystalline and uniform MLG film was obtained on the Cu foil, which was then directly coated on the Ag-NW networks to serve as a barrier material. It was found that the highly crystalline layers in the MLG film compensate for structural defects, thus forming a perfect barrier film to shield Ag NWs from oxidation and sulfurization. MLG/w-Ag-NW composites were then embedded into the surface of a transparent and colorless PI thin film by spin-coating. This allowed the MLG/w-Ag-NW/PI composite to retain its original structural integrity due to the intrinsic physical and chemical properties of PI, which also served effectively as a binder. In view of its unique sandwich structure and the chemical welding of the Ag NWs, the flexible substrate-cum-electrode had an average sheet resistance of ≈34 Ω/sq and a transmittance of ≈91% in the visible range, and also showed excellent stability against high-temperature annealing and sulfurization. Full article

(This article belongs to the Section Advanced Nanomaterials and Nanotechnology)

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28 pages, 14370 KiB

Open AccessArticle

Experimental Study on Mechanical Performance of Single-Side Bonded Carbon Fibre-Reinforced Plywood for Wood-Based Structures

by Krzysztof Szwajka, Joanna Zielińska-Szwajka, Tomasz Trzepieciński and Marek Szewczyk

Materials 2025, 18(1), 207; https://doi.org/10.3390/ma18010207 - 6 Jan 2025

Viewed by 573

Abstract

In addition to the traditional uses of plywood, such as furniture and construction, it is also widely used in areas that benefit from its special combination of strength and lightness, particularly as a construction material for the production of finishing elements of campervans [...] Read more.

In addition to the traditional uses of plywood, such as furniture and construction, it is also widely used in areas that benefit from its special combination of strength and lightness, particularly as a construction material for the production of finishing elements of campervans and yachts. In light of the current need to reduce emissions of climate-damaging gases such as CO₂, the use of lightweight construction materials is very important. In recent years, hybrid structures made of carbon fibre-reinforced plastics (CFRPs) and metals have attracted much attention in many industries. In contrast to hybrid metal/carbon fibre composites, research relating to laminates consisting of CFRPs and wood-based materials shows less interest. This article analyses the hybrid laminate resulting from bonding a CFRP panel to plywood in terms of strength and performance using a three-point bending test, a static tensile test and a dynamic analysis. Knowledge of the dynamic characteristics of carbon fibre-reinforced plywood allows for the adoption of such cutting parameters that will help prevent the occurrence of self-excited vibrations in the cutting process. Therefore, in this work, it was decided to determine the effect of using CFRP laminate on both the static and dynamic stiffness of the structure. Most studies in this field concern improving the strength of the structure without analysing the dynamic properties. This article proposes a simple and user-friendly methodology for determining the damping of a sandwich-type system. The results of strength tests were used to determine the modulus of elasticity, modulus of rupture, the position of the neutral axis and the frequency domain characteristics of the laminate obtained. The results show that the use of a CFRP-reinforced plywood panel not only improves the visual aspect but also improves the strength properties of such a hybrid material. In the case of a CFRP-reinforced plywood panel, the value of tensile stresses decreased by sixteen-fold (from 1.95 N/mm² to 0.12 N/mm²), and the value of compressive stresses decreased by more than seven-fold (from 1.95 N/mm² to 0.27 N/mm²) compared to unreinforced plywood. Based on the stress occurring at the tensile and compressive sides of the CFRP-reinforced plywood sample surface during a cantilever bending text, it was found that the value of modulus of rupture decreased by three-fold and the value of the modulus of elasticity decreased by more than five-fold compared to the unreinforced plywood sample. A dynamic analysis allowed us to determine that the frequency of natural vibrations of the CFRP-reinforced plywood panel increased by about 33% (from 30 Hz to 40 Hz) compared to the beam made only of plywood. Full article

(This article belongs to the Special Issue Towards a Sustainable and Recyclable Future with Wood and Wood-Based Composites)

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16 pages, 3700 KiB

Open AccessArticle

Effect of Depth of Cut and Number of Layers on the Surface Roughness and Surface Homogeneity After Milling of Al/CFRP Stacks

by Elżbieta Doluk, Anna Rudawska and Stanisław Legutko

Materials 2025, 18(1), 206; https://doi.org/10.3390/ma18010206 - 6 Jan 2025

Viewed by 425

Abstract

A multilayer structure is a type of construction consisting of outer layers and a core, which is mainly characterized by high strength and specific stiffness, as well as the ability to dampen vibration and sound. This structure combines the high strength of traditional [...] Read more.

A multilayer structure is a type of construction consisting of outer layers and a core, which is mainly characterized by high strength and specific stiffness, as well as the ability to dampen vibration and sound. This structure combines the high strength of traditional materials (mainly metals) and composites. Currently, sandwich structures in any configurations (types of core) are one of the main directions of technology development and research. This paper evaluates the surface quality of II- and III-layer sandwich structures that are a combination of aluminum alloy and CFRP (Carbon Fiber-Reinforced Polymer) after the machining. The effect of depth of cut (a_e) on the surface roughness of the II- and III-layer sandwich structures after the milling process was investigated. The surface homogeneity was also investigated. It was expressed by the I_Ra and I_Rz surface homogeneity indices formed from the Ra and Rz surface roughness parameters measured separately for each layer of the materials forming the sandwich structure. It was noted that the lowest surface roughness (Ra = 0.03 µm and Rz = 0.20 µm) was obtained after the milling of the II-layer sandwich structure using a_e = 0.5 mm, while the highest was obtained for the III-layer structure and a_e = 1.0 mm (Ra = 1.73 µm) and a_e = 0.5 mm (Rz = 10.98 µm). The most homogeneous surfaces were observed after machining of the II-layer structure and using the depth of cut a_e = 2.0 mm (I_Ra = 0.28 and I_Rz = 0.06), while the least homogeneous surfaces were obtained after milling of the III-layer structure and the depths of cut a_e = 0.5 mm (I_Ra = 0.64) and a_e = 2.0 mm (I_Rz = 0.78). The obtained results may be relevant to surface engineering and combining hybrid sandwich structures with other materials. Full article

(This article belongs to the Special Issue Precision and Ultra-Precision Subtractive and Additive Manufacturing Processes of Alloys and Steels, 2nd Edition)

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4 pages, 135 KiB

Open AccessEditorial

Sustainable Materials and Structures Used in Pavement Engineering

by Fucheng Guo, Augusto Cannone Falchetto, Bochao Zhou and Wentong Wang

Materials 2025, 18(1), 205; https://doi.org/10.3390/ma18010205 - 6 Jan 2025

Viewed by 423

Abstract

Sustainable materials and structures have become widely used in asphalt pavements to mitigate the resource crisis and achieve carbon neutrality [...] Full article

(This article belongs to the Special Issue Sustainable Materials and Structures Used in Pavement Engineering)

18 pages, 6311 KiB

Open AccessArticle

Herbal Waste from Filter-Tea Production as Eco-Friendly Ash for Sustainable Natural Rubber Composites

by Jelena Lubura Stošić, Oskar Bera, Teodora Vukša, Dario Balaban, Senka Vidović, Aleksandra Gavarić, Sanja B. Ostojić and Siniša Simić

Materials 2025, 18(1), 204; https://doi.org/10.3390/ma18010204 - 6 Jan 2025

Viewed by 592

Abstract

Herbal dust, a waste byproduct from filter-tea production, was annealed to form ash that can be incorporated into natural rubber as an eco-friendly filler. Three types of herbal dust ash (HDA), green tea, hibiscus, and lemon balm, were added at two different contents, [...] Read more.

Herbal dust, a waste byproduct from filter-tea production, was annealed to form ash that can be incorporated into natural rubber as an eco-friendly filler. Three types of herbal dust ash (HDA), green tea, hibiscus, and lemon balm, were added at two different contents, 2.5 and 5 phr, into the rubber compound, while the content of carbon black, as a filler, was maintained at 50 phr in all samples. The impact of HDA type and content on the rheological and mechanical properties of rubber products was evaluated. Rheological analysis showed that HDA samples exhibited slightly lower maximum torque values (around 11.6 dNm) than ash-free samples (13.53 dNm), yet maintained vulcanization effectiveness with minimal impact on torque or cure rate metrics. Mechanical testing found that samples with 2.5 phr of lemon balm ash achieved comparable properties to samples without added ash, while samples with added hibiscus preserved crosslinking density and hardness. The addition of HDA led to decreases in tensile strength, elongation at break, and hardness values, with slight changes suggesting its applicability in similar industrial contexts. The findings highlight HDAs potential as a cost-effective, sustainable filler for rubber production, contributing to circular economy practices by repurposing significant amounts of tea waste into high-quality rubber materials. Full article

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16 pages, 9326 KiB

Open AccessArticle

Creation of Long-Term Physical Stability of Amorphous Solid Dispersions N-Butyl-N-methyl-1-phenylpyrrolo[1,2-a]pyrazine-3-carboxamide, Resistant to Recrystallization Caused by Exposure to Moisture

by Vladimir B. Markeev, Evgenia V. Blynskaya, Konstantin V. Alekseev, Vladimir L. Dorofeev, Anna I. Marakhova and Alexandre A. Vetcher

Materials 2025, 18(1), 203; https://doi.org/10.3390/ma18010203 - 6 Jan 2025

Viewed by 613

Abstract

Amorphous solid dispersion (ASD) technology is often used as a promising strategy to improve the solubility of active pharmaceutical ingredients (APIs). ASDs allow APIs to be dispersed at the molecular level in a polymer carrier, destroying the crystalline structure of the APIs and, [...] Read more.

Amorphous solid dispersion (ASD) technology is often used as a promising strategy to improve the solubility of active pharmaceutical ingredients (APIs). ASDs allow APIs to be dispersed at the molecular level in a polymer carrier, destroying the crystalline structure of the APIs and, thanks to the polymer, providing long-term supersaturation in solution. However, stability issues are an obstacle to the development of new medications with ASD. In addition to the molecular mobility at elevated temperatures leading to the crystallization of APIs, moisture affects the physical stability of ASD, leading to fractional separation and recrystallization. N-butyl-N-methyl-1-phenylpyrrolo[1,2-a]pyrazine-3-carboxamide (GML-3) is an original API with both anxiolytic and antidepressant activity, but its insolubility in water can negatively affect (influence) bioavailability. Our study aims to create ASD GML-3 with moisture-resistant polymers (Soluplus^®, HPC) and assess the stability of the amorphous state of ASD after storage in high humidity conditions. As a result, HPC Klucel^TM FX was revealed to be more stable than the brand, providing a high level of API release into the purified water environment and stability after 21 days (3 weeks) of storage in high humidity conditions. Full article

(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))

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13 pages, 4333 KiB

Open AccessArticle

Design and Synthesis of Phthalocyanine-Sensitized Titanium Dioxide Photocatalysts: A Dual-Pathway Study

by Qi Shao, Jiaqi Liu, Qiwang Chen, Jing Yu, Zhongbao Luo, Rongqiang Guan, Zichen Lin, Mingxuan Li, Yi Li, Cong Liu and Yan Li

Materials 2025, 18(1), 202; https://doi.org/10.3390/ma18010202 - 5 Jan 2025

Viewed by 782

Abstract

Phthalocyanine-sensitized TiO₂ significantly enhances photocatalytic performance, but the method of phthalocyanine immobilization also plays a crucial role in its performance. In order to investigate the effect of the binding strategy of phthalocyanine and TiO₂ on photocatalytic performance, a dual-pathway study has [...] Read more.

Phthalocyanine-sensitized TiO₂ significantly enhances photocatalytic performance, but the method of phthalocyanine immobilization also plays a crucial role in its performance. In order to investigate the effect of the binding strategy of phthalocyanine and TiO₂ on photocatalytic performance, a dual-pathway study has been conducted. On the one hand, zinc-tetra (N-carbonylacrylic) aminephthalocyanine (Pc) was directly grafted onto the surface of Fe₃O₄@SiO₂@TiO₂ (FST). On the other hand, Pc was immobilized on a silane coupling agent ((3-aminopropyl) triethoxysilane) grafted onto the surface of the FST. Through photocatalytic experiments on the two types of composite materials synthesized, the results showed that the photocatalyst obtained by directly sensitizing Pc (FSTP) exhibited better performance on rhodamine B(RhB) removal than did the other photocatalyst using the silane coupling agent (FSTAP). Further mechanistic studies showed that directly sensitized FSTP exhibited more efficient photogenerated electron–hole pair separation, whereas FSTAP linked by a silane coupling agent created an additional transport distance that might greatly affect the photogenerated electron transport. Therefore, the dual-pathway research in this work provides new guidance for efficiently constructing phthalocyanine-sensitized TiO₂ photocatalysts. Full article

(This article belongs to the Topic Nanoarchitectonics with Molecular and Materials Science: Materials for Energy, Environment, Bio, and Others (2nd Edition))

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18 pages, 7630 KiB

Open AccessArticle

Evaluation of 3D-Printed Connectors in Chair Construction: A Comparative Study with Traditional Mortise-and-Tenon Joints

by Antoniu Nicolau, Marius Nicolae Baba, Camelia Cerbu, Cătălin Cioacă, Luminița-Maria Brenci and Camelia Cosereanu

Materials 2025, 18(1), 201; https://doi.org/10.3390/ma18010201 - 5 Jan 2025

Viewed by 727

Abstract

The present paper investigates the possibility of replacing the traditional L-type corner joint used in chair construction with a 3D printed connector, manufactured using the Fused Filament Fabrication (FFF) method and black PLA as filament. The connector was designed to assemble the legs [...] Read more.

The present paper investigates the possibility of replacing the traditional L-type corner joint used in chair construction with a 3D printed connector, manufactured using the Fused Filament Fabrication (FFF) method and black PLA as filament. The connector was designed to assemble the legs with seat rails and stretchers, and it was tested under diagonal tensile and compression loads. Its performance was compared to that of the traditional mortise-and-tenon joint. Stresses and displacements of the jointed members with connector were analyzed using non-linear Finite Element Method (FEM) analysis. Both connector and mortise-and-tenon joint were employed to build chair prototypes made from beech wood (Fagus sylvatica L.). Digital Image Correlation (DIC) method was used to analyze the displacements in the vicinity of the jointed members of the chairs. Seat and backrest static load tests were carried out in order to verify if the chairs withstand standard loading requirements. Results indicated that the 3D printed connector exhibited equivalent mechanical performance as the traditional joint. The recorded displacement values of the chair with 3D-printed connectors were higher than those of the traditional chair reaching 0.6 mm on the X-axis and 1.1 mm on the Y-axis, without any failures under a maximum vertical load of approximately 15 kN applied to the seat. However, it successfully withstood the loads for seating and backrest standard tests, in accordance with EN 1728:2012, without any structural failure. This paper presents a new approach for the chair manufacturing sector, with potential applicability to other types of furniture. Full article

(This article belongs to the Section Mechanics of Materials)

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13 pages, 5041 KiB

Open AccessArticle

Shape-Persistent Tetraphenylethylene Macrocycle: Highly Efficient Synthesis and Circularly Polarized Luminescence

by Peixin Liu, Yuexuan Zheng, Zejiang Liu, Zhiyao Yang, Ziying Lu, Xiongrui Ai, Zecong Ye, Cheng Yang, Xiaowei Li and Lihua Yuan

Materials 2025, 18(1), 200; https://doi.org/10.3390/ma18010200 - 5 Jan 2025

Viewed by 650

Abstract

Circularly polarized luminescence (CPL) is an emerging field with significant applications in molecular electronics, optical materials, and chiroptical sensing. Achieving efficient CPL emission in organic systems remains a major challenge, particularly in the development of materials with high fluorescence quantum yields (Φ_F [...] Read more.

Circularly polarized luminescence (CPL) is an emerging field with significant applications in molecular electronics, optical materials, and chiroptical sensing. Achieving efficient CPL emission in organic systems remains a major challenge, particularly in the development of materials with high fluorescence quantum yields (Φ_F) and large luminescence dissymmetry factors (g_lum). Herein, we report the efficient synthesis of shape-persistent tetraphenylethylene macrocycles and investigate its potential as a CPL material. Chiral side chains were introduced to induce chiroptical properties. The macrocycles and their properties were characterized using NMR, MALDI-TOF MS, FT-IR, TGA, DSC, UV-Vis spectroscopy, SEM, fluorescence spectroscopy, ECD, and CPL. A significant fluorescence enhancement was observed upon aggregation, demonstrating a typical aggregation-induced emission (AIE) behavior. Moreover, one of the macrocycles in the solid state displayed distinct CPL emission with a high g_lum of 2 × 10⁻² and a Φ_F value reaching 60%, and exhibited aggregation-induced circularly polarized luminescence (AICPL). These findings highlight the advantage of using a macrocycle with a noncollapsible backbone for the design of organic systems with CPL property, offering promising applications in chiroptical materials. Full article

(This article belongs to the Special Issue From Molecular to Supramolecular Materials)

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24 pages, 8540 KiB

Open AccessArticle

Numerical Simulation of Free Surface Deformation and Melt Stirring in Induction Melting Using ALE and Level Set Methods

by Pablo Garcia-Michelena, Emilio Ruiz-Reina, Olaia Gordo-Burgoa, Nuria Herrero-Dorca and Xabier Chamorro

Materials 2025, 18(1), 199; https://doi.org/10.3390/ma18010199 - 5 Jan 2025

Viewed by 645

Abstract

This study investigates fixed and moving mesh methodologies for modeling liquid metal–free surface deformation during the induction melting process. The numerical method employs robust coupling of magnetic fields with the hydrodynamics of the turbulent stirring of liquid metal. Free surface tracking is implemented [...] Read more.

This study investigates fixed and moving mesh methodologies for modeling liquid metal–free surface deformation during the induction melting process. The numerical method employs robust coupling of magnetic fields with the hydrodynamics of the turbulent stirring of liquid metal. Free surface tracking is implemented using the fixed mesh level set (LS) and the moving mesh arbitrary Lagrangian–Eulerian (ALE) formulation. The model’s geometry and operating parameters are designed to replicate a semi-industrial induction melting furnace. Six case studies are analyzed under varying melt masses and coil power levels, with validation performed by comparing experimentally measured free surface profiles and magnetic field distributions. The melt’s stirring velocity and recirculation patterns are also examined. The comparative analysis determines an improved performance of the ALE method, convergence, and computational efficiency. Experimental validation confirms that the ALE method reproduces the free surface shape more precisely, avoiding unrealistic topological changes observed in LS simulations. The ALE method faces numerical convergence difficulties for high-power and low-mass filling cases due to mesh element distortion. The proposed ALE-based simulation procedure is a potential numerical optimization tool for enhancing induction melting processes, offering scalable and robust solutions for industrial applications. Full article

(This article belongs to the Special Issue Electromagnetic Metallurgy: Metallurgical Process, Materials Processing and Resource Utilization)

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36 pages, 7831 KiB

Open AccessReview

The Effects of Chain Conformation and Nanostructure on the Dielectric Properties of Polymers

by Gabriel Mogbojuri, Shaghayegh Abtahi, Nayanathara Hendeniya and Boyce Chang

Materials 2025, 18(1), 198; https://doi.org/10.3390/ma18010198 - 5 Jan 2025

Viewed by 657

Abstract

The dielectric properties of polymers play a pivotal role in the development of advanced materials for energy storage, electronics, and insulation. This review comprehensively explores the critical relationship between polymer chain conformation, nanostructure, and dielectric properties, focusing on parameters such as dielectric constant, [...] Read more.

The dielectric properties of polymers play a pivotal role in the development of advanced materials for energy storage, electronics, and insulation. This review comprehensively explores the critical relationship between polymer chain conformation, nanostructure, and dielectric properties, focusing on parameters such as dielectric constant, dielectric loss, and dielectric breakdown strength. It highlights how factors like chain rigidity, free volume, molecular alignment, and interfacial effects significantly influence dielectric performance. Special emphasis is placed on the impact of nanofillers, molecular weight, crystallinity, and multilayer structures in optimizing these properties. By synthesizing findings from recent experimental and theoretical studies, this review identifies strategies to enhance energy efficiency, reliability, and mechanical stability of polymer-based dielectrics. We also delve into techniques such as electrostatic force microscopy (EFM) and focused ion beam (FIB) milling for characterizing breakdown mechanisms, offering insights into molecular design for next-generation high-performance polymers. Despite considerable progress, critical challenges such as achieving an optimal balance between dielectric permittivity and breakdown strength, understanding nanoscale interfacial phenomena, and scaling these materials for industrial applications persist. These gaps can be addressed by systematic structure–property relations, advanced processing techniques, and environmental studies. Full article

(This article belongs to the Special Issue Advances in Functional Polymers and Nanocomposites)

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20 pages, 5599 KiB

Open AccessArticle

Modification and Aging Mechanism of Crumb Rubber Modified Asphalt Based on Molecular Dynamics Simulation

by Jian Li and Liang He

Materials 2025, 18(1), 197; https://doi.org/10.3390/ma18010197 - 5 Jan 2025

Viewed by 513

Abstract

Asphalt modified with treated waste tires has good environmental protection and application value. However, the nano-modification mechanism of crumb rubber (CR) with asphalt is still unclear. This research investigates the mechanism, aging, and interfacial interaction with the aggregate of CR modification asphalt (CRMA). [...] Read more.

Asphalt modified with treated waste tires has good environmental protection and application value. However, the nano-modification mechanism of crumb rubber (CR) with asphalt is still unclear. This research investigates the mechanism, aging, and interfacial interaction with the aggregate of CR modification asphalt (CRMA). The base asphalt and CRMA (original and aged) and two typical aggregate models were constructed. The accuracy of the model was verified through multiple indicators. The effects of CR and aging on the physical properties (density, compatibility, and diffusion coefficient), mechanical properties, component interaction behavior, and interfacial interactions with aggregates of CRMA were systematically analyzed. The results showed that the CR reduced the diffusion coefficient of asphalt by about 31%. The CR inhibited the movement of the components of asphalt (especially saturate and aromatic), which significantly improved the mechanical properties of asphalt. The compatibility between asphalt and CR significantly deteriorated after aging. The difference in the solubility parameter was about four times that before aging. It is instructive for the regeneration of CRMA. Aging led to a decrease in the shear modulus and Young’s modulus of both base asphalt and CRMA, which verified and quantified the adverse effects of aging on the mechanical properties. Comparing the two aggregates, CaCO₃ had a greater adhesion with asphalt than SiO₂. The difference ranged from 22.5% to 39.9%, which quantified the difference in the adhesion properties of acid base aggregates with asphalt. This study can provide theoretical guidance for the modification and application of CRMA. Full article

(This article belongs to the Special Issue Chemical Characterization of Polymer-Modified Asphalt and Rubber-Modified Asphalt)

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15 pages, 3446 KiB

Open AccessArticle

Comparative Study on Combined Addition of Gd-Ce and Gd-Y on the Mechanical Properties and Electrochemical Behavior of Mg-Zn-Mn-Ca Alloys

by Ke Hu, Junru Zhou, Yan Zhou, Guoxian He, Wenhao Zhao, Jingjing Guo, Xiao Liu, Lingling Li and Fujian Guo

Materials 2025, 18(1), 196; https://doi.org/10.3390/ma18010196 - 5 Jan 2025

Viewed by 465

Abstract

This study presents a comparative analysis of the influence of Ce-Gd and Gd-Y additions on the microstructural evolution, mechanical properties, and electrochemical behavior of extruded Mg-3Zn-Mn-Ca alloy rods. Despite the frequent incorporation of Gd, Y, and Ce as alloying elements in magnesium alloys, [...] Read more.

This study presents a comparative analysis of the influence of Ce-Gd and Gd-Y additions on the microstructural evolution, mechanical properties, and electrochemical behavior of extruded Mg-3Zn-Mn-Ca alloy rods. Despite the frequent incorporation of Gd, Y, and Ce as alloying elements in magnesium alloys, the systematic examination of their combined effects on Mg-Zn alloys has been limited. Our findings reveal that both Gd-Ce and Gd-Y additions significantly enhance the mechanical properties of Mg-3Zn-Mn-Ca alloy, although through differing mechanisms. Specifically, the Mg-3Zn-1Mn-0.5Ca-1Gd-0.5Ce(ZMXE3101(GdCe)) alloy exhibited a yield strength of 304.5 MPa and an elongation of 15%, achieved through dynamic recrystallization and enhanced basal texture. The grain refinement and texture strengthening resulting from the coarse second-phase particles formed by Ce-Gd played a significant role in increasing the yield strength. In contrast, the Mg-3Zn-1Mn-0.5Ca-1Gd-0.5Y (ZMXE3101(GdY)) alloy demonstrated a yield strength of 305 MPa and an elongation of 20%. The finer grains and elongated unrecrystallized grains formed by Gd-Y contributed to the elevation in yield strength. While the ductility of this alloy was slightly lower than that of Mg-3Zn-Mn-Ca without rare earth additions, it still exhibited commendable overall mechanical properties. The electrochemical test results indicate that the addition of both Gd-Ce and Gd-Y enhances the corrosion current density of Mg-3Zn-Mn-Ca alloy, attributable to the generation of numerous rare earth phase particles that function as cathodes. Compared to the ZMXE3101(GdY) alloy, ZMXE3101(GdCe) exhibits a higher equilibrium potential and significantly lower corrosion current density. This is due to the formation of a protective film during the corrosion process by Gd-Ce. Full article

(This article belongs to the Section Metals and Alloys)

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13 pages, 4377 KiB

Open AccessArticle

Enhancing Catalytic Performance with Ni Foam-Coated Porous Ni Particles via 1-Butene Hydrogenation

by Dahee Park, Jung-Yeul Yun, Hye Young Koo and Yuchan Kim

Materials 2025, 18(1), 195; https://doi.org/10.3390/ma18010195 - 5 Jan 2025

Viewed by 644

Abstract

The efficient hydrogenation of 1-butene is an industrially significant reaction for producing fuels and value-added chemicals. However, achieving high catalytic efficiency and stability remains challenging, particularly for cost-effective materials, such as Ni. In this study, we developed a porous Ni-coated Ni foam catalyst [...] Read more.

The efficient hydrogenation of 1-butene is an industrially significant reaction for producing fuels and value-added chemicals. However, achieving high catalytic efficiency and stability remains challenging, particularly for cost-effective materials, such as Ni. In this study, we developed a porous Ni-coated Ni foam catalyst by electrostatic spray deposition to address these challenges. The catalyst exhibited a turnover frequency approximately 10 times higher than that of either porous Ni or Ni foam alone. This enhancement was attributed to the formation of interfacial active sites, which facilitated improved reactant adsorption and activation during hydrogenation. The electrostatic spray deposition technique ensured a uniform and controlled coating, enabling precise engineering of the catalyst structure and interface. The post-deposition heat treatment was further optimized to enhance structural integrity and catalytic performance. This study highlights the importance of interface engineering and structural optimization in catalyst design and provides valuable insights into the development of efficient Ni-based catalysts for industrial hydrogenation applications. These findings emphasize the potential of electrostatic spray deposition as a versatile method for fabricating advanced catalytic systems. Full article

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23 pages, 17563 KiB

Open AccessArticle

Creep Resistance and Microstructure Evolution in P23/P91 Welds

by Vlastimil Vodárek, Jan Holešinský, Zdeněk Kuboň, Renáta Palupčíková, Petra Váňová and Jitka Malcharcziková

Materials 2025, 18(1), 194; https://doi.org/10.3390/ma18010194 - 5 Jan 2025

Viewed by 389

Abstract

This paper summarizes the results of investigations into heterogeneous P23/P91 welds after long-term creep exposure at temperatures of 500, 550 and 600 °C. Two variants of welds were studied: In Weld A, the filler material corresponded to P91 steel, while in Weld B, [...] Read more.

This paper summarizes the results of investigations into heterogeneous P23/P91 welds after long-term creep exposure at temperatures of 500, 550 and 600 °C. Two variants of welds were studied: In Weld A, the filler material corresponded to P91 steel, while in Weld B, the chemical composition of the consumable material matched P23 steel. The creep rupture strength values of Weld A exceeded those of Weld B at all testing temperatures. Most failures in the cross-weld samples occurred in the partially decarburized zones of P23 or WM23 steel. The results of the investigations on the minor phases were in good agreement with kinetic simulations that considered a 0.1 mm fusion zone. Microstructural studies proved that carburization occurred in the P23/P91 weld fusion zones. The partial decarburization of P23 steel or WM23 was accompanied by the dissolution of M₇C₃ and M₂₃C₆ particles, and detailed studies revealed the precipitation of the Fe₂ (W, Mo) Laves phase in decarburized areas. Thermodynamic simulations proved that the appearance of this phase in partially decarburized P23 steel or WM23 is related to a reduction in the carbon content in these areas. According to the results of creep tests, the EBSD investigations revealed a better microstructural stability of the partially decarburized P23 steel in Weld A. Full article

(This article belongs to the Special Issue Advanced Materials Joining and Manufacturing Techniques)

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25 pages, 9242 KiB

Open AccessArticle

Influence of Machining Parameters on the Surface Roughness and Tool Wear During Slot Milling of a Polyurethane Block

by Karolina Szadkowska, Norbert Kępczak, Wojciech Stachurski, Witold Pawłowski, Radosław Rosik, Grzegorz Bechciński, Małgorzata Sikora, Błażej Witkowski and Jakub Sikorski

Materials 2025, 18(1), 193; https://doi.org/10.3390/ma18010193 - 5 Jan 2025

Viewed by 450

Abstract

The aim of the work was to investigate the influence of the machining parameters on the surface roughness and tool wear during slot milling of a polyurethane block (PUB). In the experiment, the influence of the cutting speed, the feed per tooth and [...] Read more.

The aim of the work was to investigate the influence of the machining parameters on the surface roughness and tool wear during slot milling of a polyurethane block (PUB). In the experiment, the influence of the cutting speed, the feed per tooth and the depth of cut on the roughness Ra and Rz of the milling slot surface and wear of the end mill was analyzed. A three-axis CNC milling machine Emco Concept Mill 55 was used to perform the study. After the machining, the values of parameters Ra and Rz were measured using the Hommel Tester T500 induction profilometer. Three polyurethane materials of different densities were considered: the Labelite 45, the Prolab 65 and the LAB 1000. The wear of the end mill was also examined for each of the tested materials by a workshop microscope. In conclusion, it was indicated how and to what extent the variation in the machining parameters affects the surface geometrical structure of a polyurethane plate. Moreover, the research results for the tested materials were compared with each other. Full article

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22 pages, 5640 KiB

Open AccessArticle

Experiment and Simulation Study on the Crashworthiness of Markforged 3D-Printed Carbon/Kevlar Hybrid Continuous Fiber Composite Honeycomb Structures

by Jinlong Ju, Nana Yang, Lei Yu, Zhe Zhang, Hongyong Jiang, Wenhua Wu and Guolu Ma

Materials 2025, 18(1), 192; https://doi.org/10.3390/ma18010192 - 5 Jan 2025

Viewed by 482

Abstract

Fiber hybridization can effectively solve the localized brittle fracture problem of composite honeycomb, but the interaction between different fibers leads to a very complex failure mechanism. Hence, 3D-printed hybrid continuous fiber composite honeycombs with a combination of carbon and Kevlar fibers are designed [...] Read more.

Fiber hybridization can effectively solve the localized brittle fracture problem of composite honeycomb, but the interaction between different fibers leads to a very complex failure mechanism. Hence, 3D-printed hybrid continuous fiber composite honeycombs with a combination of carbon and Kevlar fibers are designed to study the structural failure behaviors by the experiment and simulation method. The experimental samples, including Onyx, carbon, Kevlar, carbon/Kevlar, and Kevlar/carbon composites, are fabricated based on Markforged 3D printing technology, and the crushing tests are conducted to evaluate the failure behaviors. An equivalence finite element modeling method to replace the heterogeneous microstructure of hybrid composites is proposed to analyze the failure behaviors. Results indicate that carbon/Kevlar honeycomb exhibits the highest energy absorption and cost effectiveness, while CFRP honeycomb demonstrates the highest load-carrying capacity. It is found that carbon/Kevlar and Kevlar/carbon honeycombs have significant hybrid effects compared to single-fiber honeycombs, which also reveals the hybrid mechanisms between carbon and Kevlar fibers. Furthermore, the Onyx honeycomb, lacking long fibers, exhibits brittle collapse, whereas other honeycombs show ductile collapse due to the presence of Kevlar fibers. Combining the simulation studies, the damage evolution mechanisms of honeycombs, including fiber/matrix tension and compression, shear damage, interface damage, etc., are further revealed. This work provides valuable insights into the design and failure analysis of 3D-printed hybrid fiber composite honeycombs. Full article

(This article belongs to the Special Issue 3D-Printed Composite Structures: Design, Properties and Application)

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13 pages, 3305 KiB

Open AccessArticle

Surface Wettability Modeling and Predicting via Artificial Neural Networks

by Katarzyna Peta

Materials 2025, 18(1), 191; https://doi.org/10.3390/ma18010191 - 5 Jan 2025

Viewed by 512

Abstract

Surface wettability, defined by the contact angle, describes the ability of a liquid to spread over, absorb or adhere to a solid surface. Surface wetting analysis is important in many applications, such as lubrication, heat transfer, painting and wherever liquids interact with solid [...] Read more.

Surface wettability, defined by the contact angle, describes the ability of a liquid to spread over, absorb or adhere to a solid surface. Surface wetting analysis is important in many applications, such as lubrication, heat transfer, painting and wherever liquids interact with solid surfaces. The behavior of liquids on surfaces depends mainly on the texture and chemical properties of the surface. Therefore, these studies show the possibility of modeling surface wettability by adjusting the parameters of the surface texturing process. The prediction of the contact angle describing the wettability of the surface was performed using artificial neural networks. In order to select the most effective prediction model, the activation functions of neurons, the number of hidden layers and the network training algorithms were changed. The neural network model presented in these studies is capable of predicting the contact angle with an efficiency defined by the coefficient of determination R² between real and predicted contact angles of over 0.9. Full article

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40 pages, 9273 KiB

Open AccessReview

Revisiting Intercalation Anode Materials for Potassium-Ion Batteries

by María José Piernas-Muñoz and Maider Zarrabeitia

Materials 2025, 18(1), 190; https://doi.org/10.3390/ma18010190 - 4 Jan 2025

Viewed by 987

Abstract

Potassium-ion batteries (KIBs) have attracted significant attention in recent years as a result of the urgent necessity to develop sustainable, low-cost batteries based on non-critical raw materials that are competitive with market-available lithium-ion batteries. KIBs are excellent candidates, as they offer the possibility [...] Read more.

Potassium-ion batteries (KIBs) have attracted significant attention in recent years as a result of the urgent necessity to develop sustainable, low-cost batteries based on non-critical raw materials that are competitive with market-available lithium-ion batteries. KIBs are excellent candidates, as they offer the possibility of providing high power and energy densities due to their faster K⁺ diffusion and very close reduction potential compared with Li⁺/Li. However, research on KIBs is still in its infancy, and hence, more investigation is required both at the materials level and at the device level. In this work, we focus on recent strategies to enhance the electrochemical properties of intercalation anode materials, i.e., carbon-, titanium-, and vanadium-based compounds. Hitherto, the most promising anode materials are those carbon-based, such as graphite, soft, or hard carbon, each with its advantages and disadvantages. Although a wide variety of strategies have been reported with excellent results, there is still a need to improve the standardization of the best carbon properties, electrode formulation, and electrolyte composition, given the impossibility of a direct comparison. Therefore, additional effort should be made to understand what are the crucial carbon parameters to develop a reference electrode and electrolyte formulation to further boost their performance and move a step forward in the commercialization of KIBs. Full article

(This article belongs to the Special Issue Advanced Anode Materials for Alkali-Ion Batteries)

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15 pages, 4674 KiB

Open AccessArticle

A Method for Determining the Minimum Thickness of the Cut Layer in Precision Milling

by Lukasz Nowakowski, Mateusz Bronis, Slawomir Blasiak and Michal Skrzyniarz

Materials 2025, 18(1), 189; https://doi.org/10.3390/ma18010189 - 4 Jan 2025

Viewed by 620

Abstract

The minimum cutting thickness is a key value in machining processes, as below this value the material will only undergo elastic and plastic deformation without chip removal. Existing measurement methods require time-consuming preparation and complicated procedures. This work focuses on the development of [...] Read more.

The minimum cutting thickness is a key value in machining processes, as below this value the material will only undergo elastic and plastic deformation without chip removal. Existing measurement methods require time-consuming preparation and complicated procedures. This work focuses on the development of a new, simplified method for determining the minimum cutting thickness (h_min) using a contact profilometer that can be used in industry. The use of the contact measurement method has made it possible to directly determine the value of the h_min parameter, to determine the length of the characteristic zones of interaction of the tool with the surface of the specimen, and to measure the angle of inclination of the working plane of the specimen. Measurement using a profilometer allows for the obtainment of results with high resolution, which greatly facilitates the identification of zones of tool interaction with the workpiece material during the cutting test and reduces the value of the measurement error. The proposed method simplifies the specimen preparation process by using rectangular specimens positioned on an inclined plane, which allows the depth of the cut to be varied smoothly. This paper presents experimental results and statistical analysis. Tests were carried out on C45 steel, and an ANOVA analysis was carried out to evaluate the effect of the grinding parameters on the h_min parameter. It was found that the feed rate had the largest effect on h_min (93%), while cutting speed had a smaller effect. A mathematical model was developed to predict values based on selected technological parameters such as cutting speed and feed per tooth. Full article

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12 pages, 5879 KiB

Open AccessArticle

Advanced Thermoelectric Performance of SWCNT Films by Mixing Two Types of SWCNTs with Different Structural and Thermoelectric Properties

by Yutaro Okano, Hisatoshi Yamamoto, Koki Hoshino, Shugo Miyake and Masayuki Takashiri

Materials 2025, 18(1), 188; https://doi.org/10.3390/ma18010188 - 4 Jan 2025

Viewed by 568

Abstract

Semiconducting single-walled carbon nanotubes (SWCNTs) are significantly attractive for thermoelectric generators (TEGs), which convert thermal energy into electricity via the Seebeck effect. This is because the characteristics of semiconducting SWCNTs are perfectly suited for TEGs as self-contained power sources for sensors on the [...] Read more.

Semiconducting single-walled carbon nanotubes (SWCNTs) are significantly attractive for thermoelectric generators (TEGs), which convert thermal energy into electricity via the Seebeck effect. This is because the characteristics of semiconducting SWCNTs are perfectly suited for TEGs as self-contained power sources for sensors on the Internet of Things (IoT). However, the thermoelectric performances of the SWCNTs should be further improved by using the power sources. The ideal SWCNTs have a high electrical conductivity and Seebeck coefficient while having a low thermal conductivity, but it is challenging to balance everything. In this study, to improve the thermoelectric performance, we combined two types of SWCNTs: one with a high electrical conductivity (Tuball 01RW03, OCSiAl) and the other with a high Seebeck coefficient and low thermal conductivity (ZEONANO SG101, ZEON). The SWCNT inks were prepared by mixing two types of SWCNTs using ultrasonic dispersion while varying the mixing ratios, and p-type SWCNT films were prepared using vacuum filtration. The highest dimensionless figure-of-merit of 1.1 × 10⁻³ was exhibited at approximately 300 K when the SWCNT film contained the SWCNT 75% of SWCNT (ZEONANO SG101) and 25% of SWCNT (Tuball 01RW03). This simple process will contribute to the prevalent use of SWCNT-TEG as a power source for IoT sensors. Full article

(This article belongs to the Special Issue Advances in Hybrid Energy Harvesting: Materials, Structures and Applications)

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19 pages, 16670 KiB

Open AccessArticle

Study on Fire Temperature Field in Small-Section Steel-Shell Concrete Immersed Tube Tunnel Structure Based on CFD-FEM Method

by Bei Zhao, Baochao Xie, Zhisheng Xu, Feifan Wang and Yifan Gao

Materials 2025, 18(1), 187; https://doi.org/10.3390/ma18010187 - 4 Jan 2025

Viewed by 443

Abstract

Small-section steel-shell concrete immersed tube tunnels are intended for minibuses and have a low fire heat release rate. Standard fire rise curves do not apply to such tunnels. In this study, a coupled method of computational fluid dynamics (CFD) and the finite element [...] Read more.

Small-section steel-shell concrete immersed tube tunnels are intended for minibuses and have a low fire heat release rate. Standard fire rise curves do not apply to such tunnels. In this study, a coupled method of computational fluid dynamics (CFD) and the finite element method (FEM) was used to simulate the structural temperature distribution in tunnels. Firstly, a tunnel fire dynamics model was established to obtain the inhomogeneous temperature field during tunnel fires. Subsequently, a three-dimensional heat transfer analysis model for the tunnel tube section was established to simulate the temperature transfer characteristics of the tunnel structure with and without fire protection measures under different types of vehicle fires. This study showed that because steel has a higher thermal conductivity, at the same depth, the temperatures were the highest in T-ribs, followed by partitions, and the lowest in concrete; however, the steel components inside the tunnel minimally affected the tunnel temperature. Without fire protection, the steel shell’s surface temperature exceeded 300 °C in as little as 500 s. Temperature’s primary impact on the tunnel’s steel structure was within 30 cm of the steel shell’s surface, and on concrete, it was within 20 cm. The greatest temperature difference between the partition and concrete occurred 10 cm from the steel shell’s surface. These results fill the knowledge gap on heat transfer in these tunnels and have positive practical significance for the fire resistance design of tunnels. Full article

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15 pages, 3058 KiB

Open AccessArticle

Computational Study of Chalcogenide-Based Perovskite Solar Cell Using SCAPS-1D Numerical Simulator

by Edson L. Meyer, Sinikiwe A. Mvokwe, Opeoluwa O. Oyedeji, Nicholas Rono and Mojeed A. Agoro

Materials 2025, 18(1), 186; https://doi.org/10.3390/ma18010186 - 4 Jan 2025

Viewed by 716

Abstract

Perovskite solar cells (PSCs) are regarded as extremely efficient and have significant potential for upcoming photovoltaic technologies due to their excellent optoelectronic properties. However, a few obstacles, which include the instability and high costs of production of lead-based PSCs, hinder their commercialization. In [...] Read more.

Perovskite solar cells (PSCs) are regarded as extremely efficient and have significant potential for upcoming photovoltaic technologies due to their excellent optoelectronic properties. However, a few obstacles, which include the instability and high costs of production of lead-based PSCs, hinder their commercialization. In this study, the performance of a solar cell with a configuration of FTO/CdS/BaZrS₃/HTL/Ir was optimized by varying the thickness of the perovskite layer, the hole transport layer, the temperature, the electron transport layer (ETL)’s defect density, the absorber defect density, the energy band, and the work function for back contact. Various hole transport layers (HTLs), including Cu₂O, CuSCN, P3HT, and PEDOT:PSS, were assessed to select the best materials that would achieve high performance and stability in PSC devices. At optimal levels, PEDOT:PSS reached a maximum power conversion efficiency (PCE) of 18.50%, while P3HT, CuSCN, and Cu₂O exhibited a PCE of 5.81, 10.73, and 9.80%, respectively. The high performance exhibited by PEDOT:PSS was attributed to better band alignment between the absorber and the PEDOT:PSS, and, thus, a low recombination of photogenerated charges. The other photovoltaic parameters for the best device were a short-circuit current density (J_sc) of 23.46 mA cm⁻², an open-circuit voltage (V_oc) of 8.86 (V), and a fill factor (FF) of 8.90%. This study highlights the potential of chalcogenide-based PSCs as an efficient and stable alternative to traditional lead-based solar cells, with successful optimization paving the way for future research on eco-friendly materials and scalable production methods. Full article

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18 pages, 5282 KiB

Open AccessArticle

Mechanical and Catalytic Degradation Properties of Porous FeMnCoCr High-Entropy Alloy Structures Fabricated by Selective Laser Melting Additive Manufacturing

by Lyusha Cheng, Cheng Deng, Yushan Huang, Kai Li and Changjun Han

Materials 2025, 18(1), 185; https://doi.org/10.3390/ma18010185 - 4 Jan 2025

Viewed by 547

Abstract

This work investigated the mechanical and catalytic degradation properties of FeMnCoCr-based high-entropy alloys (HEAs) with diverse compositions and porous structures fabricated via selective laser melting (SLM) additive manufacturing for wastewater treatment applications. The effects of Mn content (0, 30 at%, and 50 at%) [...] Read more.

This work investigated the mechanical and catalytic degradation properties of FeMnCoCr-based high-entropy alloys (HEAs) with diverse compositions and porous structures fabricated via selective laser melting (SLM) additive manufacturing for wastewater treatment applications. The effects of Mn content (0, 30 at%, and 50 at%) and topological structures (gyroid, diamond, and sea urchin-inspired shell) on the compression properties and catalytic efficiency of the Fe_80-xMn_xCo₁₀Cr₁₀ HEAs were discussed. The results indicated that an increase in the Mn content led to a phase structure transition that optimized mechanical properties and catalytic activities. Among the designed structures, the gyroid HEA structure exhibited the highest compressive yield strength, reaching 197 MPa. Additionally, Fe₃₀Mn₅₀Co₁₀Cr₁₀ HEA exhibited exceptional performance in catalytic degradation experiments by effectively degrading simulated pollutants with a significantly enhanced rate by 22.3% compared to other compositions. The Fe_80-xMn_xCo₁₀Cr₁₀ HEA catalyst fabricated by SLM demonstrated high stability over multiple cycles. These findings reveal that porous FeMnCoCr-based HEAs have significant potential for catalytic degradation of organic pollutants, providing valuable insights for future catalyst design and development in efficient and sustainable wastewater treatment. Full article

(This article belongs to the Special Issue Fabrication of Advanced Materials)

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