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Materials, Volume 18, Issue 17 (September-1 2025) – 294 articles

Cover Story (view full-size image): Our work unveils a scalable strategy to fabricate robust superhydrophobic surfaces on copper, producing water contact angles exceeding 170° and exhibiting low hysteresis. This is achieved through precisely engineered micro/nano-architectures combined with a conformal, low-surface-energy coating formed via chemical vapor deposition. The resulting surface traps air beneath water droplets, even in underwater conditions, limiting contact between copper and corrosive agents. Electrochemical and salt spray tests demonstrate a corrosion rate reduction of 85.7%, corresponding to a sevenfold improvement over bare copper. This approach offers a practical, reproducible path toward durable, multifunctional surfaces suitable for anti-fouling, self-cleaning, and long-term corrosion protection in harsh environments. View this paper
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18 pages, 1627 KB  
Article
First-Principles Study of Strain Engineering Regulation of SnSe Thermoelectric Properties
by Haoru Zhang, Songqing Zhao, Yuhong Xia, Xinyue Zhang, Lulu Zhou and Zhenqing Yang
Materials 2025, 18(17), 4219; https://doi.org/10.3390/ma18174219 - 8 Sep 2025
Viewed by 459
Abstract
To study the effect of strain engineering on the thermoelectric properties of SnSe, we combined first-principles calculation and Boltzmann transport theory to study the effect of −4% to 4% strain on SnSe thermoelectric properties. Compressive strain enhances the maximum power factor (PF [...] Read more.
To study the effect of strain engineering on the thermoelectric properties of SnSe, we combined first-principles calculation and Boltzmann transport theory to study the effect of −4% to 4% strain on SnSe thermoelectric properties. Compressive strain enhances the maximum power factor (PFmax) of p-type SnSe from 2.3 to 4.3 mW·m−1·K−2. Specifically, under a −3% compressive strain, the thermoelectric figure of merit (ZT) experiences a 50% enhancement, increasing from 0.18 to 0.27. Conversely, for n-type, tensile strain leads to a 26% rise in the PFₘₐₓ, from 53.6 to 67.6 mW·m−1·K−2. Notably, the 4% tensile strain increased the ZT value of n-type SnSe by 123% from 0.66 to 1.47. Importantly, tensile strain effectively reduces lattice thermal conductivity through enhanced phonon scattering, synergistically improving ZT with the enhanced power factor. The results show that strain can effectively improve the thermoelectric properties of SnSe, and that n-type SnSe has great potential in thermoelectric materials. Full article
(This article belongs to the Section Materials Simulation and Design)
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15 pages, 4634 KB  
Article
Accelerated Corrosion and Multimodal Characterization of Steel Pins in High-Voltage AC Insulators Under Multi-Stress Conditions
by Cong Zhang, Heng Zhong, Zikui Shen, Hongyan Zheng, Yibo Yang, Junbin Su and Xiaotao Fu
Materials 2025, 18(17), 4218; https://doi.org/10.3390/ma18174218 - 8 Sep 2025
Viewed by 328
Abstract
Ensuring the long-term electro-mechanical reliability of high-voltage alternating current (HVAC) insulator strings requires a detailed understanding of how multiple environmental and electrical stressors influence the corrosion behavior of hot-dip galvanized steel fittings. In this study, a three-factor, three-level L9(33) orthogonal accelerated [...] Read more.
Ensuring the long-term electro-mechanical reliability of high-voltage alternating current (HVAC) insulator strings requires a detailed understanding of how multiple environmental and electrical stressors influence the corrosion behavior of hot-dip galvanized steel fittings. In this study, a three-factor, three-level L9(33) orthogonal accelerated corrosion test was conducted to systematically evaluate the individual and interactive effects of marine salt deposition (0–10 g m−2 day−1), acetic acid pollution (0–8 µg m−3), and 50 Hz AC leakage current (0–10 mA) on miniature pin-type assemblies. A comprehensive post-corrosion characterization approach was employed. The results revealed that chloride loading from salt deposition was the dominant contributor to corrosion. However, the synergistic interaction between salt and leakage current led to an acceleration in zinc depletion compared to the additive effect of the individual factors. A quadratic regression model with a high correlation coefficient was developed to predict corrosion volume per unit area. The findings offer a mechanistic explanation for field-reported failures in coastal power grids and provide actionable guidance for optimizing corrosion-resistant coatings and implementing electrical mitigation strategies. Full article
(This article belongs to the Section Corrosion)
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23 pages, 4614 KB  
Article
Strength Tests of Selected Ropes Used in Mining Shaft Hoists After Their Replacement in Stochastic Interpretation
by Andrzej Tytko, Grzegorz Olszyna, Tomasz Rokita and Krzysztof Skrzypkowski
Materials 2025, 18(17), 4217; https://doi.org/10.3390/ma18174217 - 8 Sep 2025
Viewed by 358
Abstract
As the reserves of these raw materials continue to dwindle, their extraction is becoming increasingly difficult, with shaft depth increasing and sometimes exceeding three kilometres. As shaft depths increase, the costs, as well as the risks of mining and other shaft operations, increase [...] Read more.
As the reserves of these raw materials continue to dwindle, their extraction is becoming increasingly difficult, with shaft depth increasing and sometimes exceeding three kilometres. As shaft depths increase, the costs, as well as the risks of mining and other shaft operations, increase non-linearly. There is also a significant increase in the costs associated with condition assessment, which depend on the inspection and testing method used and increase with the lifetime of the facility. New technical and organisational solutions are emerging to meet these requirements. This paper addresses the operation of steel ropes. This article analyses the results of strength tests on two selected modern hoisting rope designs that have recently come into service. These structures are relatively unknown to users in terms of their wear. In their operation, significant problems of condition assessment and safety, as well as disqualification due to the level of wear reached, arise. Strength tests were performed using classic non-destructive methods (tensile test, torsion test, bending test) to assess the technical condition of ropes after their replacement. The tests on two rope structures carried out before and after they were put down by expert decision were analyzed. The results of these tests were statistically processed and presented graphically to determine similarities and differences. Statistical analyses were used to evaluate the results by examining the distribution of variable strength parameters. All results were commented on, and specific and general conclusions were drawn. The article presents the conclusions, the most important of which is that new and complex ropes exhibit varying degrees of wear across the layers. This is due to their compaction process. These should be useful to users of similar rope designs, personnel carrying out the obligatory tests imposed by the legislation, and those making strategic decisions regarding the operation of entire mining plants. The analyses may contribute to the subsequent assessment of the technical condition of new ropes, which in many cases have wear parameters (corrosion, strength loss, etc.) assessed in a subjective, not quantitative, manner. Full article
(This article belongs to the Section Construction and Building Materials)
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12 pages, 1290 KB  
Article
Aluminium Injection Mould Behaviour Using Additive Manufacturing and Surface Engineering
by Marcelo José de Lima, Jorge Luis Braz Medeiros, José de Souza, Carlos Otávio Damas Martins and Luciano Volcanoglo Biehl
Materials 2025, 18(17), 4216; https://doi.org/10.3390/ma18174216 - 8 Sep 2025
Viewed by 427
Abstract
This study evaluates the application of metal additive manufacturing—specifically the laser powder bed fusion (LPBF) process—for producing aluminium die-casting mould components, comparing 300-grade maraging steel inserts with conventional H13 tool steel. Efficient thermal management and mould durability are critical in aluminium injection moulding. [...] Read more.
This study evaluates the application of metal additive manufacturing—specifically the laser powder bed fusion (LPBF) process—for producing aluminium die-casting mould components, comparing 300-grade maraging steel inserts with conventional H13 tool steel. Efficient thermal management and mould durability are critical in aluminium injection moulding. Still, traditional machining limits the design of cooling channels, resulting in hot spots, accelerated wear, and a reduced service life. LPBF allows the fabrication of complex geometries, enabling conformal cooling channels to enhance thermal control. Component samples were manufactured using maraging steel via LPBF, machined to final dimensions, and subjected to duplex surface treatment (plasma nitriding + CrAlN PVD coating). Thermal performance, dimensional stability, mechanical properties, and wear resistance were experimentally assessed under conditions simulating industrial production. The results demonstrate that LPBF components with optimised cooling channels and surface engineering achieve higher thermal efficiency, an extended service life (up to 2.6×), improved hardness profiles (545 HV0.05 core, 1230 HV0.05 on nitrided surface and 2850 HV0.05 after PVD film deposition), and reduced maintenance frequencies compared to H13 inserts. The study confirms that additive manufacturing, combined with tailored surface treatments and optimised cooling design, overcomes the geometric and thermal limitations of conventional manufacturing, offering a reliable and productive solution for aluminium die-casting moulds. Full article
(This article belongs to the Special Issue 3D & 4D Printing in Engineering Applications, 2nd Edition)
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19 pages, 3474 KB  
Article
Shear Band Formation in Thin-Film Multilayer Columns Under Compressive Loading: A Mechanistic Study
by Yu-Lin Shen and Kasandra Escarcega Herrera
Materials 2025, 18(17), 4215; https://doi.org/10.3390/ma18174215 - 8 Sep 2025
Viewed by 390
Abstract
Micro-pillar compression is a popular experimental technique used for characterizing the mechanical behavior of nano- and micro-laminates. The compressive stress–strain response of the column-shaped thin-film composite can be measured, and the deformation and damage features can be revealed by post-test cross-section microscopy. The [...] Read more.
Micro-pillar compression is a popular experimental technique used for characterizing the mechanical behavior of nano- and micro-laminates. The compressive stress–strain response of the column-shaped thin-film composite can be measured, and the deformation and damage features can be revealed by post-test cross-section microscopy. The development of plastic instability in the form of localized strain concentration (shear bands), leading to eventual failure, is frequently observed. In the present study, a computational approach is used to illustrate the commonality of shear band formation from a continuum standpoint. Systematic finite element analyses are conducted, showing that the strain field tends to become localized once plastic yielding commences. Distinct shear offsets of the layered structure can be revealed from the numerical model, which is similar to those observed in experiments. The actual appearance of shear bands depends on the materials’ constitutive behavior and precise geometries. Post-yield strain hardening reduces the propensity of shear band formation, while strain softening enhances it. Imperfections such as the undulated layer geometry, as well as the frictional characteristics between the specimen and test apparatus, can also influence the shear band morphology and overall stress–strain response. Full article
(This article belongs to the Special Issue Computational Tools for Predicting Mechanical Properties of Materials)
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19 pages, 11731 KB  
Article
Effect of Post-Weld Heat Treatment on Microstructure and Hardness Evolution of the Martensitic Hardfacing Layers for Hot Forging Tools Repair
by Marzena Lachowicz, Marcin Kaszuba, Paweł Widomski and Paweł Sokołowski
Materials 2025, 18(17), 4214; https://doi.org/10.3390/ma18174214 - 8 Sep 2025
Viewed by 302
Abstract
The study investigates the influence of post-weld heat treatment (PWHT) on the microstructure and hardness of hardfacing layers applied to hot forging tools. The research focuses on three tool steels (55NiCrMoV7, X37CrMoV5-1, and a modified X38CrMoV5-3) and uses robotized gas metal arc welding [...] Read more.
The study investigates the influence of post-weld heat treatment (PWHT) on the microstructure and hardness of hardfacing layers applied to hot forging tools. The research focuses on three tool steels (55NiCrMoV7, X37CrMoV5-1, and a modified X38CrMoV5-3) and uses robotized gas metal arc welding (GMAW) with DO015 filler material. It examines the structural and mechanical differences in the hardfaced layers before and after heat treatment involving quenching and tempering. The findings reveal that PWHT significantly improves microstructural homogeneity and hardness distribution, especially in the heat-affected zone (HAZ), mitigating the risk of crack initiation and tool failure. The study shows that untempered as-welded layers exhibit microstructural inhomogeneity and extreme hardness gradients, which negatively impact tool durability. PWHT leads to tempered martensite formation, grain refinement, and a more stable hardness profile across the joint. These improvements are critical for extending the service life of forging tools. The results underscore the importance of customizing PWHT parameters according to the specific material and application to optimize tool performance. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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22 pages, 8131 KB  
Article
Study on Graphene-Reinforced Epoxy Solvent-Borne High-Temperature-Resistant Adhesives for Bonding C/C Composites Under Extreme Temperatures
by Yue Wang, Yuqing Zhang, Zhanming Hu, Jingjing Li, Zhuo Gao, Mingchao Wang and Haijun Zhang
Materials 2025, 18(17), 4213; https://doi.org/10.3390/ma18174213 - 8 Sep 2025
Viewed by 292
Abstract
Drawing inspiration from the bionic nacre structure, graphene was incorporated into the epoxy solvent-borne adhesive to construct a laminated architecture. At the same time, ferrocene was employed as a catalyst to induce the in situ growth of carbon nanotubes (CNTs) under high-temperature conditions. [...] Read more.
Drawing inspiration from the bionic nacre structure, graphene was incorporated into the epoxy solvent-borne adhesive to construct a laminated architecture. At the same time, ferrocene was employed as a catalyst to induce the in situ growth of carbon nanotubes (CNTs) under high-temperature conditions. This modification endowed the epoxy solvent-borne adhesive with not only high strength in atmospheric environments but also the capability to retain considerable mechanical performance at elevated temperatures. Experimental results demonstrated that when the graphene content in the epoxy solution fell within the range of 3.2–4%, the bonding strength exceeded 3 MPa within the temperature range of 1000–1300 °C. In particular, the adhesive exhibited excellent thermal shock resistance, with no degradation in strength observed after 15 thermal shock cycles at 1300 °C. Such exceptional performance was attributed to the formation of interlaminar CNTs generated after high-temperature treatment. Scanning electron microscopy (SEM) observations clearly revealed the laminated graphene sheets and in situ grown CNTs, confirming the feasibility of the strategy to enhance bonding efficacy by mimicking the nacre structure. This approach represented an innovative breakthrough for further research on the application of the “brick-and-mortar” structure in the bonding layer and the in situ growth of CNTs among lamellar graphene, while also providing detailed supporting data. Full article
(This article belongs to the Section Advanced and Functional Ceramics and Glasses)
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21 pages, 4092 KB  
Article
Assessment of Time-Dependent Hydration Products in Olivine-Substituted Cement Mortars
by Yusuf Tahir Altuncı and Cenk Öcal
Materials 2025, 18(17), 4212; https://doi.org/10.3390/ma18174212 - 8 Sep 2025
Viewed by 388
Abstract
It is known that approximately 8% of atmospheric carbon dioxide (CO2) emissions originate from cement production. Consequently, there is ongoing rapid research into environmentally friendly and alternative materials that could substitute for cement. Olivine [(Mg, Fe)2SiO4] is [...] Read more.
It is known that approximately 8% of atmospheric carbon dioxide (CO2) emissions originate from cement production. Consequently, there is ongoing rapid research into environmentally friendly and alternative materials that could substitute for cement. Olivine [(Mg, Fe)2SiO4] is an abundant mineral in the Earth’s crust that facilitates CO2 sequestration due to its high solubility. This study investigates the effects of hydration mechanisms in olivine-substituted cement mortars on their compressive strength, microstructural characteristics, and physical properties. For this purpose, standard cement mortars were produced using CEM IV 32.5 N-type cement with olivine substitution rates of 0%, 10%, and 20%. The compressive strength of the specimens was initially determined at 7, 28, and 90 days. Subsequently, the hydration mechanisms at 7, 28, and 90 days were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Differential Thermal Analysis/Thermogravimetric Analysis (DTA/TG), and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS). The results demonstrated that the 10% substitution rate complies with the BS EN 196-1 standard, and olivine can be substituted for CEM IV type cement up to 10% without requiring calcination. Full article
(This article belongs to the Special Issue Innovative Construction Materials for Sustainable and Greener Applications)
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32 pages, 9080 KB  
Article
The Influence of Selected Properties of Sintered Iron Doped with Lubricants on Its Tribological Properties
by Wiesław Urbaniak, Tomasz Majewski, Grzegorz Śmigielski, Anna Trynda and Aneta D. Petelska
Materials 2025, 18(17), 4211; https://doi.org/10.3390/ma18174211 - 8 Sep 2025
Viewed by 405
Abstract
This study investigated materials intended for use in porous bearings, incorporating selected layered materials. Previous research has demonstrated that layered compounds, such as molybdenum disulfide (MoS2), tungsten disulfide (WS2), and hexagonal boron nitride (h-BN), can significantly enhance tribological performance. [...] Read more.
This study investigated materials intended for use in porous bearings, incorporating selected layered materials. Previous research has demonstrated that layered compounds, such as molybdenum disulfide (MoS2), tungsten disulfide (WS2), and hexagonal boron nitride (h-BN), can significantly enhance tribological performance. However, these improvements in tribological properties may be accompanied by undesirable characteristics that could limit the practical application of such materials. Therefore, further investigation was necessary to gain a better understanding of their behavior. To this end, composite materials containing iron (Fe) and varying amounts (0.5, 2.5, and 5 wt%) of layered materials were fabricated using powder metallurgy and sintering techniques. The study evaluated the impact of compaction pressure applied before sintering on the tribological properties and hardness of the materials. Additionally, the long-term stability of the composites was assessed after six years of storage under ambient conditions. The results confirmed that incorporating layered materials into the structure of porous bearing materials improves operating conditions and reduces the coefficient of friction by more than 20%. However, after six years of ambient storage, only the samples containing h-BN remained unchanged. Samples containing WS2 or MoS2 exhibited partial degradation, with evident signs of corrosion and grain fragmentation. Full article
(This article belongs to the Section Metals and Alloys)
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19 pages, 6881 KB  
Article
Electrochemical Reduction of CO2 to C2 Hydrocarbons Using Cu 3D Nanostructures
by Birutė Serapinienė, Evaldas Naujalis, Algirdas Selskis, Jurga Juodkazytė and Rimantas Ramanauskas
Materials 2025, 18(17), 4210; https://doi.org/10.3390/ma18174210 - 8 Sep 2025
Viewed by 393
Abstract
Although Cu 3D structures are widely used in electrocatalytic practice, this electrode has not been studied enough in relation to the electrochemical transformation of CO2 to C2 products. Cu foam samples were deposited from acidic solutions with varying concentrations of primary components [...] Read more.
Although Cu 3D structures are widely used in electrocatalytic practice, this electrode has not been studied enough in relation to the electrochemical transformation of CO2 to C2 products. Cu foam samples were deposited from acidic solutions with varying concentrations of primary components (H2SO4, CuSO4, and Cl− ions) with the aim of determining the relationship between catalyst structure and activity/selectivity in producing C2 gaseous compounds during CO2 electrochemical reduction. The deposited samples were characterized using SEM and electrochemical techniques, including Pb underpotential deposition (UPD), to determine the contribution of crystal facets. The most efficient electrodes were found to be those deposited in a solution without Cl− additives. Their effectiveness was related to the shape and size of the crystallites forming the branches. These crystallites create a spatial structure that supports C-C coupling and C2 gaseous compound formation. The higher catalytic activity and selectivity of this electrode may also be related to its lower Cu(111) facet input to the overall facet distribution and its higher number of structural defects. Despite the higher electrochemically active surface area of samples deposited in the presence of Cl− ions, their lower activity is related to structural characteristics that cause possible mass transfer limitations. Full article
(This article belongs to the Section Advanced Nanomaterials and Nanotechnology)
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16 pages, 3001 KB  
Article
Experimental and Simulation Investigation of Octadecyltriethoxysilane-Decorated Diatomaceous Earth Coatings with Enhanced Superhydrophobic and Self-Cleaning Properties
by Aijia Zhang, Nan Xiao, Kunjie Yuan and Wenbin Cao
Materials 2025, 18(17), 4209; https://doi.org/10.3390/ma18174209 - 8 Sep 2025
Viewed by 377
Abstract
In this study, an effective diatomaceous earth (Dia)/octadecyltriethoxysilane (OTS)/epoxy resin (EP) with enhanced superhydrophobic and self-cleaning coating was prepared by spraying method, and the effect of OTS modification on the hydrophobicity of Dia materials was investigated through molecular dynamics computational simulation. The results [...] Read more.
In this study, an effective diatomaceous earth (Dia)/octadecyltriethoxysilane (OTS)/epoxy resin (EP) with enhanced superhydrophobic and self-cleaning coating was prepared by spraying method, and the effect of OTS modification on the hydrophobicity of Dia materials was investigated through molecular dynamics computational simulation. The results showed that the number of hydrogen bonds and electrostatic interaction energy between diatomite and water molecules were significantly reduced after OTS modification, which significantly enhanced the hydrophobicity of diatomite. The coating exhibits excellent superhydrophobic properties, with a contact angle of up to 152.3°, and has a wide range of applicability, being able to uniformly cover a wide range of substrate surfaces such as glass, wood, and aluminium panels. In addition, it demonstrates excellent self-cleaning capabilities, effectively removing surface contaminants. The mechanical and chemical stability of the coating has also been thoroughly investigated, and it remains superhydrophobic even after abrasion tests and shows excellent stability in acidic or alkaline corrosive environments. Molecular dynamics calculations further elucidated the reason for the change in hydrophobicity of the coatings in acidic and alkaline environments, revealing that the diffusion of water molecules slows down in alkaline environments and solid–liquid interactions are enhanced, resulting in a slight decrease in hydrophobicity. The results of this study not only provide new ideas for the low-cost and environmentally friendly preparation of superhydrophobic materials but also provide a solid theoretical basis and practical guidance for further optimising the material properties. Full article
(This article belongs to the Special Issue Superhydrophobic Interfaces and Surfaces: Preparation, Characterization, and Applications)
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30 pages, 4727 KB  
Article
Modified Fine Recycled Concrete Aggregates with a Crystallizing Agent as Standard Sand Replacement in Mortar
by Daniel Suarez-Riera, Luca Lavagna, Devid Falliano, Giuseppe Andrea Ferro, Matteo Pavese, Jean-Marc Tulliani and Luciana Restuccia
Materials 2025, 18(17), 4208; https://doi.org/10.3390/ma18174208 - 8 Sep 2025
Viewed by 437
Abstract
This study aimed to evaluate mortar performance by substituting part of standard sand with recycled fine aggregates sourced from concrete waste, aiming to assess mechanical properties and durability. Moreover, this study examined the use of crystallizing agents to understand their impact on mortar [...] Read more.
This study aimed to evaluate mortar performance by substituting part of standard sand with recycled fine aggregates sourced from concrete waste, aiming to assess mechanical properties and durability. Moreover, this study examined the use of crystallizing agents to understand their impact on mortar properties. Four mortar series were prepared with sand substitution percentages ranging from 25% to 100% while adhering to the diverse fraction proportions within the standardized sand particle size distribution. Mechanical results indicate that incorporating recycled concrete sand significantly enhances mechanical properties with respect to standard sand. The study showed the technical feasibility of producing mortars with up to 100% recycled fine concrete aggregate with enhanced compressive strength, albeit requiring higher superplasticizer dosages. The addition of crystallizing agents provided an increase in flexural strength in specific conditions, while they did not provide a significant improvement to compressive strength. Full article
(This article belongs to the Special Issue Emerging Technologies and Materials for Smart, Durable and Sustainable Construction)
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19 pages, 4203 KB  
Article
Study on Triaxial Properties of Calcareous Sand Modified with Volcanic Ash Cement and Graphene Oxide
by Jun Hu, Zhaokui Sun, Chenming Xu, Zetian Li, Yahui Zhan, Yu Li, Shuai Zhang and Yuxuan Zhou
Materials 2025, 18(17), 4207; https://doi.org/10.3390/ma18174207 - 8 Sep 2025
Viewed by 361
Abstract
Calcareous sand, characterized by numerous pore spaces, easy fragmentation, and low strength, is commonly used as fill material in island construction projects. Due to these limitations, it often fails to meet the requirements of actual engineering applications. This paper uses oxidized graphene in [...] Read more.
Calcareous sand, characterized by numerous pore spaces, easy fragmentation, and low strength, is commonly used as fill material in island construction projects. Due to these limitations, it often fails to meet the requirements of actual engineering applications. This paper uses oxidized graphene in combination with fly ash cement to modify calcareous sand. The effects of oxidized graphene, fly ash cement, and curing time on the modification effect were investigated through triaxial tests and numerical simulations. The experimental results show the following: (1) Both the extension of curing age and the increase in the dosage of fly ash cement can improve the shear performance of calcareous sand, with the increase in the dosage of fly ash cement able to ensure thorough bonding between calcareous sand particles. (2) Graphene oxide can significantly improve the shear performance of calcareous sand cement mortar, with the optimal dosage being 0.06%. Excess amounts result in a reduced performance improvement, which is related to the degree of the catalysis of oxidized graphene on hydration reactions. (3) The numerical simulation shows that when the maximum shear stress reached 3437 kPa, cracks began appearing on the specimen, consistent with the experimental results. Meanwhile, the numerical simulation results reveal the crack propagation pattern in the specimens, showing that the stress at crack initiation is lower than the peak stress. Full article
(This article belongs to the Section Construction and Building Materials)
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36 pages, 20557 KB  
Review
The Microstructure Regulation Mechanism and Future Application of Aluminum Alloys Manipulated by Nanocrystalline Structures Formed by In Situ Amorphous Crystallization
by Wen-Bo Yang, Lei Zhan, Lin Liu, Fan-Xu Meng, Run Zhang, Kadiredan Tuerxun, Xing-Rui Zhao, Bai-Xin Dong, Shi-Li Shu, Tian-Shu Liu, Hong-Yu Yang, Feng Qiu and Qi-Chuan Jiang
Materials 2025, 18(17), 4206; https://doi.org/10.3390/ma18174206 - 8 Sep 2025
Viewed by 465
Abstract
The present study concentrates on the role and underlying mechanisms of in situ crystallization (employed for nanocrystal formation) in influencing the solidification microstructure and properties of aluminum alloys. By systematically analyzing the effects on α-Al refinement, silicon phase modification, and secondary phase control, [...] Read more.
The present study concentrates on the role and underlying mechanisms of in situ crystallization (employed for nanocrystal formation) in influencing the solidification microstructure and properties of aluminum alloys. By systematically analyzing the effects on α-Al refinement, silicon phase modification, and secondary phase control, as well as exploring the impact on room-temperature mechanical properties, high-temperature deformation behavior, and fatigue performance, this work reveals the potential physical mechanisms of improving mechanical properties by providing nucleation sites and inhibiting grain growth, such as fine-grain strengthening and dispersion strengthening. Moreover, stabilization of the second phase optimizes high-temperature deformation behavior, and a reduction in stress concentration improves fatigue performance. Compared with traditional microstructure control methods, in situ crystallization can achieve deeper grain refinement from micron to nanometer scale, ensuring high uniformity of grain distribution and showing good compatibility with existing processes. By defining the regulation of in situ crystallization on the microstructure and properties of aluminum alloy, the existing research provides a feasible material solution for high stress, high temperature, and high reliability. Its core significance lies in breaking through the performance bottlenecks of traditional modification technology, such as unstable refining effect, element segregation, and so on. The co-promotion of “strength–plasticity–stability” of aluminum alloys and the consideration of process compatibility and cost controllability lay a theoretical and technical foundation for the industrialization of high-performance aluminum alloys. Full article
(This article belongs to the Special Issue Processing and Characteristics of Metal Matrix Composites)
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19 pages, 4380 KB  
Article
Optimization of Casting Process Parameters for Solidification Structures in Complex Superalloy Castings
by Shaoli Han, Heli Luo, Shangping Li and Guangwei Han
Materials 2025, 18(17), 4205; https://doi.org/10.3390/ma18174205 - 8 Sep 2025
Viewed by 374
Abstract
This study aimed to optimize the grain structure of complex thin-walled nickel-based superalloy castings by investigating the influence of key casting parameters using both cellular automaton–finite element (CAFE) simulations and experimental validation. The main problem addressed was the inhomogeneous grain morphology arising from [...] Read more.
This study aimed to optimize the grain structure of complex thin-walled nickel-based superalloy castings by investigating the influence of key casting parameters using both cellular automaton–finite element (CAFE) simulations and experimental validation. The main problem addressed was the inhomogeneous grain morphology arising from complex mold geometries and uneven thermal conditions during investment casting. The solidification process was simulated using the ProCAST software, incorporating the CAFE method to model temperature fields and grain growth dynamics. The results revealed that the molten metal flow pattern during mold filling significantly affected the local temperature field and subsequent grain formation. Specifically, simultaneous bidirectional filling minimized thermal gradients and suppressed coarse columnar grain formation, promoting finer, more uniform equiaxed grains. Lowering the pouring temperature (to 1430 °C) in combination with reduced shell temperature (600–800 °C) enhanced nucleation and improved grain uniformity in thin-walled regions. Higher cooling rates also refined the grain structure by increasing undercooling and limiting grain growth. Experimental castings confirmed these simulation outcomes, demonstrating that the proposed optimization strategies can significantly improve grain homogeneity in critical structural areas. These findings provide a practical approach for controlling microstructure in large, intricate superalloy components through targeted process parameter tuning. Full article
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20 pages, 11441 KB  
Article
Mechanism and Optimized Design Methodology of Steel Plate Reinforcement for Tunnel Lining Void Zones
by Shuai Shao, Yimin Wu, Helin Fu and Jiawei Zhang
Materials 2025, 18(17), 4204; https://doi.org/10.3390/ma18174204 - 8 Sep 2025
Viewed by 382
Abstract
Voids behind tunnel linings are common hidden defects in underground engineering, leading to reduced structural capacity and potential safety hazards. To address the deficiencies in the understanding of the mechanism and the optimization of design of the existing steel plate reinforcement methods, this [...] Read more.
Voids behind tunnel linings are common hidden defects in underground engineering, leading to reduced structural capacity and potential safety hazards. To address the deficiencies in the understanding of the mechanism and the optimization of design of the existing steel plate reinforcement methods, this study systematically investigates the reinforcement mechanisms and proposes refined design strategies through numerical simulations and experimental validation. First, a comparative analysis of the Concrete Damage Plasticity (CDP) model and the Extended Finite Element Method (XFEM) revealed that the CDP model exhibits superior accuracy and computational efficiency in simulating large-scale void linings. Second, the effectiveness of different reinforcement schemes (chemical anchor bolts alone, structural adhesive alone, and combined systems) was evaluated, demonstrating that structural adhesive dominates stress transfer, while chemical anchor bolts primarily prevent plate detachment. Through further optimization simulations of the steel plate spacing, it was found that a spacing of 0.25 m can balance the reinforcement effect and cost. This spacing restricts the maximum principal stress (1.83 MPa) below the tensile strength of concrete while essentially eliminating damage to the lower surface of the lining. An optimized steel plate reinforcement structure was ultimately proposed. By reducing the number of chemical anchor bolts and decreasing their size (with only M12 chemical anchor bolts arranged at the edges), local damage is minimized while maintaining reinforcement efficiency. The research results provide theoretical support and engineering guidance for the safe repair of tunnel void areas. Full article
(This article belongs to the Section Construction and Building Materials)
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16 pages, 2209 KB  
Article
The Interference Mechanism and Regularity Analysis of Gas Pipelines Affected by High-Speed Rail Based on Field Testing and Numerical Simulation
by Yuxing Zhang, Caigang Ge, Ziru Chang, Yanxia Du, Minxu Lu and Zitao Jiang
Materials 2025, 18(17), 4203; https://doi.org/10.3390/ma18174203 - 8 Sep 2025
Viewed by 393
Abstract
By monitoring the alternating interference voltage at the intersections and parallels of gas pipelines with high-speed railways, the alternating voltage between the high-speed railway track supports and the ground, the alternating ground voltage gradient along parallel and perpendicular high-speed railway tracks, and the [...] Read more.
By monitoring the alternating interference voltage at the intersections and parallels of gas pipelines with high-speed railways, the alternating voltage between the high-speed railway track supports and the ground, the alternating ground voltage gradient along parallel and perpendicular high-speed railway tracks, and the timing of train passages, the interference patterns caused by high-speed railways on pipelines are analyzed. A numerical model was developed to elucidate interference mechanisms. The conclusions indicate that the interference caused by the parallel and intersecting presence of high-speed railways and pipelines is far greater than that caused solely by the intersection of railways and pipelines. The peak alternating voltage interference on pipelines occurs at the insulation joints of the pipelines, the positions of the pipelines corresponding to the high-speed railway track circuits (AT), and the positions of the pipelines corresponding to the passage of trains. The alternating interference caused by high-speed railway lines on pipelines involves both resistive coupling interference and electromagnetic induction coupling interference, with the latter dominating. Full article
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19 pages, 5772 KB  
Article
Reducing Cement Clinker Sintering Temperature Using Fluorine-Containing Semiconductor Waste
by Bilguun Mend, Youngjun Lee, Jang-Ho Jay Kim and Yong-Sik Chu
Materials 2025, 18(17), 4202; https://doi.org/10.3390/ma18174202 - 8 Sep 2025
Viewed by 401
Abstract
This study investigated the potential use of fluorine-containing semiconductor industrial sludge as a mineralizer in Portland cement clinker production. Raw mixes were prepared by partially replacing raw materials with 6%, 9%, and 12% sludge and sintered between 1300 and 1500 °C. The clinker [...] Read more.
This study investigated the potential use of fluorine-containing semiconductor industrial sludge as a mineralizer in Portland cement clinker production. Raw mixes were prepared by partially replacing raw materials with 6%, 9%, and 12% sludge and sintered between 1300 and 1500 °C. The clinker burnability, phase composition, and chemical integrity were evaluated through FreeCaO measurements, X-ray diffraction (XRD) with Rietveld refinement, and X-ray fluorescence (XRF) analyses. The results showed that sludge addition reduced the sintering temperature by up to 150 °C, enabling near-complete clinker formation at 1300 °C for blends containing 9% and 12% sludge (FreeCaO ≤ 0.6 wt.% compared to 62 wt.% in the reference sample). Fluorine incorporation stabilized the re-active β–C2S polymorph and shifted the alite (C3S) phase distribution from stable M1 to metastable M3 and T3 phases. Additionally, the C3A phase content decreased, and a unique fluorine-containing phase, Al7Ca6O16F, formed, promoting clinker formation. Lowering the sintering temperature led to energy savings of 15–22.5% and reduced CO2 emissions by 0.10–0.20 tons per ton of clinker, positively impacting the environment. This study demonstrates that recycling industrial sludge can enhance cement production efficiency and support environmental sustainability. Full article
(This article belongs to the Topic Novel Cementitious Materials)
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17 pages, 820 KB  
Article
AI-Driven Optimization of Cu2O Modified Bitumen: A Multi-Scale Evaluation of Rheological, Aging, and Moisture Susceptibility Performance
by Sebnem Karahancer
Materials 2025, 18(17), 4201; https://doi.org/10.3390/ma18174201 - 8 Sep 2025
Viewed by 451
Abstract
This study explores the integration of copper oxide (Cu2O) into bitumen and leverages Artificial Intelligence (AI) to evaluate and optimize the binder’s performance across multiple scales. Comprehensive laboratory tests, including conventional binder properties, rheological analysis, aging simulations, low-temperature cracking, and moisture [...] Read more.
This study explores the integration of copper oxide (Cu2O) into bitumen and leverages Artificial Intelligence (AI) to evaluate and optimize the binder’s performance across multiple scales. Comprehensive laboratory tests, including conventional binder properties, rheological analysis, aging simulations, low-temperature cracking, and moisture susceptibility, were conducted on base and Cu2O modified asphalt binders. The results were used to train predictive models using gradient boosting regressors for each performance category. Optimization identified ideal Cu2O ratios for different engineering goals, offering practical recommendations. Based on this integrated cost-performance analysis, a Cu2O concentration of 2.3% was recommended as the most efficient trade-off point. AI modeling using Gradient Boosting Regressor (GBR) achieved high predictive performance, with R2 values reaching 0.98 for BBR prediction and 0.78 for rheology, and mean absolute error (MAE) values as low as 4.21. This demonstrates the model’s robustness in capturing complex nonlinear binder behaviors. Full article
(This article belongs to the Special Issue Artificial Intelligence (AI)-Driven Full Lifecycle Management of Infrastructures: From Advanced Cementitious Materials to Durable Structures)
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19 pages, 2661 KB  
Article
Analysis of the Permeability Capacity and Engineering Performance of Porous Asphalt Concrete
by Huan Wang, Lintao Li, Zebang Deng, Pengguang Liu and Dingbang Wei
Materials 2025, 18(17), 4200; https://doi.org/10.3390/ma18174200 - 8 Sep 2025
Viewed by 605
Abstract
This study investigates the permeability performance and engineering performance of porous asphalt concrete (PAC) mixtures. PAC-10 and PAC-13 mixture specimens with various porosities were prepared. The relationships among porosity, effective porosity, and effective porosity proportion were analyzed, and the pavement engineering performance was [...] Read more.
This study investigates the permeability performance and engineering performance of porous asphalt concrete (PAC) mixtures. PAC-10 and PAC-13 mixture specimens with various porosities were prepared. The relationships among porosity, effective porosity, and effective porosity proportion were analyzed, and the pavement engineering performance was evaluated. Moreover, the effects of nominal maximum aggregate size (NMAS) and porosity characteristics on the permeability coefficient were also examined. The results indicate that both the effective porosity and the effective porosity proportion increase with total porosity for both the PAC-10 and PAC-13 mixtures. PAC-13 consistently exhibits a higher effective porosity than PAC-10, suggesting enhanced drainage performance. The designed PAC mixtures satisfy the requirements of high-temperature stability and moisture resistance for asphalt pavements, while the large porosity is contradictory with high-temperature stability and moisture resistance. Additionally, the permeability coefficient significantly increases with larger NMAS, and a strong linear correlation is observed between permeability and both total and effective porosity, where the coefficient of determination (R2) is larger than 0.9. These findings demonstrate that porosity parameters can serve as reliable indicators for assessing the permeability performance of PAC mixtures with different gradations. Full article
(This article belongs to the Collection Advanced Civil Engineering Materials: From Synthesis to Application)
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27 pages, 11392 KB  
Article
The Influence of Structural Constraints and Configurations on Corrosion-Induced Cracking in Reinforced Concrete Based on the Phase-Field Method
by Pengfei Zhang, Lingye Leng, Wenqiang Xu, Sheng Qiang, Hui Wang and Ziang Zhao
Materials 2025, 18(17), 4199; https://doi.org/10.3390/ma18174199 - 7 Sep 2025
Viewed by 1205
Abstract
Corrosion-induced cracking of reinforced-concrete (RC) covers is well known, yet key knowledge gaps persist. Most studies isolate uniform corrosion or a single non-uniform corrosion pattern and ignore the effects of boundary restraint and structural configurations, leading to inaccurate predictions of cracking thresholds and [...] Read more.
Corrosion-induced cracking of reinforced-concrete (RC) covers is well known, yet key knowledge gaps persist. Most studies isolate uniform corrosion or a single non-uniform corrosion pattern and ignore the effects of boundary restraint and structural configurations, leading to inaccurate predictions of cracking thresholds and crack propagation patterns. This study systematically investigates the influence mechanisms of constraint conditions and structural configurations on corrosion-induced cracking behavior using the phase-field model. The results indicate that the non-uniformity of steel corrosion is a critical factor governing cover cracking. As the corrosion non-uniformity coefficient increases, the critical corrosion level exhibits a monotonic decreasing trend—from 0.95% to 0.15% under strong constraints and from 0.52% to 0.15% under weak constraints. Concurrently, the crack morphology evolves from a single radial crack to a wedge-shaped crack oriented toward the peak corrosion side. The influence of constraint conditions is dualistic, while strong constraints enhance the failure threshold, their mitigating effect diminishes markedly under highly non-uniform corrosion. The critical corrosion threshold for eccentrically arranged corner reinforcement is significantly lower than that for centrally arranged reinforcement; the corrosion angle only induces slight crack deflection and minor threshold fluctuations; and the curved top section, due to its weaker equivalent constraint, exhibits inferior crack resistance compared to the linear top section. Three-dimensional analysis reveals a pronounced longitudinal discreteness effect, which not only substantially elevates the critical corrosion threshold but also leads to diverse spatial failure modes. This work links rust-expansion eigen-displacement to crack propagation within a unified phase-field framework, providing materials-level criteria for evaluating corrosion tolerance and guiding the design of cover materials and reinforcement layouts to enhance durability. Full article
(This article belongs to the Special Issue Corrosion of Materials: Evaluation, Testing, Protection, and Failure Analysis, Third Edition)
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8 pages, 1354 KB  
Communication
Synergistic Deformation of Ferrite/Martensite Laminates Brings High Strength and Good Ductility in Dual-Phase Steel
by Lijuan Zhang, Pengzhan Cai, Ling Zhang, Ziyong Hou and Guilin Wu
Materials 2025, 18(17), 4198; https://doi.org/10.3390/ma18174198 - 7 Sep 2025
Viewed by 550
Abstract
A low-carbon ferrite/martensite-laminated 0.1C5Mn3Al dual-phase steel was hot-rolled to an engineering strain of 98%, and a tensile strength of 1277 ± 44 MPa and a total elongation of 11.8 ± 0.4% was obtained in the steel. Hot-rolling induces a laminated/layered structure characterized by [...] Read more.
A low-carbon ferrite/martensite-laminated 0.1C5Mn3Al dual-phase steel was hot-rolled to an engineering strain of 98%, and a tensile strength of 1277 ± 44 MPa and a total elongation of 11.8 ± 0.4% was obtained in the steel. Hot-rolling induces a laminated/layered structure characterized by alternating ferrite phases and martensite phases distributed perpendicular to the rolling direction. A deformation mechanism was evaluated using nano-indentation and in situ compression of micropillars in a scanning electron microscope. The excellent mechanical properties of the steel are attributed to the refinement of ferrite/martensite layers and ultra-fine martensite laths. The synergistic deformation of the ferrite and martensite laminates provides the steel with a good combination of high strength and tensile elongation. Full article
(This article belongs to the Topic Microstructure and Properties in Metals and Alloys, 3rd Volume)
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13 pages, 3800 KB  
Article
Mechanical and Tribological Properties of Porous Cu-15Ni-8Sn Alloy Fabricated Through Selective Laser Melting for Application in Self-Lubricating Bearing
by Hui Chen, Gengming Zhang, Jianling Liu and Shichao Liu
Materials 2025, 18(17), 4197; https://doi.org/10.3390/ma18174197 - 7 Sep 2025
Viewed by 481
Abstract
Additive manufacturing techniques, such as selective laser melting (SLM), enable the production of intricate and integrated components made from metallic materials with inherent porosity. The pores, typically perceived as defects, are commonly observed on the surface or within the matrix of SLM-formed components. [...] Read more.
Additive manufacturing techniques, such as selective laser melting (SLM), enable the production of intricate and integrated components made from metallic materials with inherent porosity. The pores, typically perceived as defects, are commonly observed on the surface or within the matrix of SLM-formed components. However, it is noteworthy that these pores can function as reservoirs for lubricants to enhance tribological performance in specific applications, such as porous bearings. In this study, the optimum conditions for fabricating Cu-15Ni-8Sn alloy porous bearings via SLM technology were investigated. By regulating laser power and hatch space during SLM processing, Cu-15Ni-8Sn alloy porous bearings were successfully obtained. The resulting oil bearings exhibited an oil content exceeding 18% and a radial crushing strength surpassing 370 MPa. At reduced laser power (80 W) and increased hatch spacing (0.9 mm), average friction coefficients of 0.1 and 0.13 were observed, with volumetric wear values of 10.3 mm3 and 96.7 mm3, respectively. The friction mechanism is a combination of abrasive wear and delamination wear. Full article
(This article belongs to the Special Issue Advances in Al/Mg/Cu Alloys and Their Composites: Welding, Additive Manufacturing, Heterogeneous Microstructures, and Mechanical Properties)
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16 pages, 15757 KB  
Review
The Impact of Molecular Weight Distribution on the Crystalline Texture of Polymers—Illustrated by Lamellar Crystal, Shish–Kebab and Nested Spherulites
by Songyan Lu, Min Chen and Hanying Li
Materials 2025, 18(17), 4196; https://doi.org/10.3390/ma18174196 - 7 Sep 2025
Viewed by 645
Abstract
Manipulating polymer crystallization behavior and structure without altering chemical composition remains a core challenge in polymer crystallography. Molecular weight, as an intrinsic material property, governs the crystallization process from nucleation through growth. Synthetic polymer materials exhibit molecular weight distribution (MWD), resulting in polydisperse [...] Read more.
Manipulating polymer crystallization behavior and structure without altering chemical composition remains a core challenge in polymer crystallography. Molecular weight, as an intrinsic material property, governs the crystallization process from nucleation through growth. Synthetic polymer materials exhibit molecular weight distribution (MWD), resulting in polydisperse polymer chains within one system. This MWD drives distinct crystalline structures, whereas synergistic crystallization behaviors arise among chains of various lengths. MWD yields complex crystallization behaviors. Especially, spatial molecular weight distribution induces novel crystalline textures in polymer materials. Elucidating the crystallization mechanisms is vital for understanding structure-property relationships in polymers. Herein, the recent advances in the various influences of MWD on polymer crystal textures are systematically demonstrated. Full article
(This article belongs to the Special Issue Research Progress of Advanced Crystals: Growth and Doping)
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24 pages, 5175 KB  
Review
Photoluminescence Enhancement in Perovskite Nanocrystals via Compositional, Ligand, and Surface Engineering
by Chae-Mi Lee, Eun-Hoo Jeong, Ho-Seong Kim, Seo-Yeon Choi and Min-Ho Park
Materials 2025, 18(17), 4195; https://doi.org/10.3390/ma18174195 - 7 Sep 2025
Viewed by 639
Abstract
Perovskite nanocrystals (PeNCs) have attracted considerable interest as promising materials for next-generation optoelectronic devices owing to their high photoluminescence quantum yield, narrow emission linewidths, simple composition tunability, and solution processability. However, the practical applicability of these NCs is limited by their compositional, thermal, [...] Read more.
Perovskite nanocrystals (PeNCs) have attracted considerable interest as promising materials for next-generation optoelectronic devices owing to their high photoluminescence quantum yield, narrow emission linewidths, simple composition tunability, and solution processability. However, the practical applicability of these NCs is limited by their compositional, thermal, and environmental instabilities, which compromise their long-term operational performance and reliability. Compositional instability arises from ion migration and phase segregation, leading to spectral shifts and unstable emission. Thermal degradation is driven by volatile organic cations and weak surface bonding, while environmental factors such as moisture, oxygen, and ultraviolet irradiation promote defect formation and material degradation. This review describes the recent advances in improving the photoluminescent stability of PeNCs through compositional engineering (A-/B-site substitution), ligand engineering (X-/L-type modulation), and surface passivation strategies. These approaches effectively suppress degradation pathways while maintaining or improving the optical properties of PeNCs. By performing a comparative analysis of these strategies, this review provides guidelines for the rational design of stable and efficient PeNCs for light-emitting applications. Full article
(This article belongs to the Section Energy Materials)
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22 pages, 836 KB  
Article
Energy Consumption and Carbon Emissions of Compressed Earth Blocks Stabilized with Recycled Cement
by Alessandra Ranesi, Ricardo Cruz, Vitor Sousa and José Alexandre Bogas
Materials 2025, 18(17), 4194; https://doi.org/10.3390/ma18174194 - 6 Sep 2025
Viewed by 571
Abstract
Driven by the pursuit of more sustainable materials, earth construction has seen renewed interest in recent years. However, chemical stabilization is often required to ensure adequate water resistance. While recycled cement from concrete waste (RCC) has recently emerged as a more sustainable alternative [...] Read more.
Driven by the pursuit of more sustainable materials, earth construction has seen renewed interest in recent years. However, chemical stabilization is often required to ensure adequate water resistance. While recycled cement from concrete waste (RCC) has recently emerged as a more sustainable alternative to ordinary Portland cement (OPC) for soil stabilization, its environmental impact remains unassessed. A hybrid model, built on collected data and direct simulations, was implemented to estimate energy and carbon emissions of compressed earth blocks (CEBs) stabilized with RCC as a partial or total replacement of OPC. Four operational scenarios were assessed in a cradle-to-gate approach, evaluating the environmental impact per CEB unit, and normalizing it to the CEB compressive strength. OPC CEBs showed up to 9 times higher energy consumption (2.46 vs. 0.24 MJ/CEB) and about 35 times higher carbon emissions (0.438 vs. 0.012 kgCO2/CEB) than UCEBs. However, replacing OPC with RCC reduced energy consumption by up to 8% and carbon emissions by up to 64%. Although RCC CEBs showed lower mechanical strength, resulting in higher energy consumption when normalized to compressive strength, carbon emissions remained up to 48% lower compared to OPC CEBs. RCC emerged as a more sustainable alternative to OPC for earth stabilization, while also improving the mechanical strength and durability of UCEBs. Full article
(This article belongs to the Special Issue Green and Sustainable Infrastructure Construction Materials (3rd Edition))
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25 pages, 15114 KB  
Article
Strength Characteristics of Straw-Containing Cemented Tailings Backfill Under Different Strain Rates
by Zeyu Li, Xiuzhi Shi, Xin Chen, Jinzhong Zhang, Wenyang Wang and Xiaoyuan Li
Materials 2025, 18(17), 4193; https://doi.org/10.3390/ma18174193 - 6 Sep 2025
Viewed by 571
Abstract
The frequent blasting in underground mines results in stress waves of different intensities, which is one of the main factors leading to backfill collapse. Improving the strength of backfill is an effective way to reduce the backfill damage. In this study, rice straw [...] Read more.
The frequent blasting in underground mines results in stress waves of different intensities, which is one of the main factors leading to backfill collapse. Improving the strength of backfill is an effective way to reduce the backfill damage. In this study, rice straw fiber and graded tailings were used as raw materials to prepare rice straw fiber-reinforced cemented tailings backfill (RSCTB). An orthogonal experimental design was employed to perform unconfined compressive strength (UCS) tests, diffusivity measurements, and Split Hopkinson Pressure Bar (SHPB) tests. The results showed that straw fibers slightly reduce slurry fluidity. The UCS of RSCTB at a specific mix ratio was more than 50% higher than that of cemented tailings backfill (CTB) without rice straw. The dynamic unconfined compressive strength (DUCS) of RSCTB increased linearly at different strain rates. The effect of rice straw fibers on the UCS and DUCS was much smaller than that of cement content and solid mass concentration. Excessively long and abundant straw fibers are not conducive to improving the long-term impact resistance of RSCTB. Full article
(This article belongs to the Special Issue Sustainable Construction and Building Materials: Microstructure, Mechanical Performance, and Long-Term Durability)
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29 pages, 4547 KB  
Article
Process Modeling and Micromolding Optimization of HA- and TiO2-Reinforced PLA/PCL Composites for Cannulated Bone Screws via AI Techniques
by Min-Wen Wang, Jui-Chia Liu and Ming-Lu Sung
Materials 2025, 18(17), 4192; https://doi.org/10.3390/ma18174192 - 6 Sep 2025
Viewed by 528
Abstract
A bioresorbable cannulated bone screw was developed using PLA/PCL-based composites reinforced with hydroxyapatite (HA) and titanium dioxide (TiO2), two additives previously reported to enhance mechanical compliance, biocompatibility, and molding feasibility in biodegradable polymer systems. The design incorporated a crest-trimmed thread and [...] Read more.
A bioresorbable cannulated bone screw was developed using PLA/PCL-based composites reinforced with hydroxyapatite (HA) and titanium dioxide (TiO2), two additives previously reported to enhance mechanical compliance, biocompatibility, and molding feasibility in biodegradable polymer systems. The design incorporated a crest-trimmed thread and a strategically positioned gate in the thin-wall zone opposite the hexagonal socket to preserve torque-transmitting geometry during micromolding. To investigate shrinkage behavior, a Taguchi orthogonal array was employed to systematically vary micromolding parameters, generating a structured dataset for training a back-propagation neural network (BPNN). Analysis of variance (ANOVA) identified melt temperature as the most influential factor affecting shrinkage quality, defined by a combination of shrinkage rate and dimensional variation. A hybrid AI framework integrating the BPNN with genetic algorithms and particle swarm optimization (GA–PSO) was applied to predict the optimal shrinkage conditions. This is the first use of BPNN–GA–PSO for cannulated bone screw molding, with the shrinkage rate as a targeted output. The AI-predicted solution, interpolated within the Taguchi design space, achieved improved shrinkage quality over all nine experimental groups. Beyond the specific PLA/PCL-based systems studied, the modeling framework—which combines geometry-specific gate design and normalized shrinkage prediction—offers broader applicability to other bioresorbable polymers and hollow implant geometries requiring high-dimensional fidelity. This study integrates composite formulation, geometric design, and data-driven modeling to advance the precision micromolding of biodegradable orthopedic devices. Full article
(This article belongs to the Special Issue Advances in Functional Polymers and Nanocomposites)
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19 pages, 5777 KB  
Article
Enhancing the Mechanical and Frost Resistance Properties of Sustainable Concrete Using Fired Pumice Aggregates
by Mahiro Hokazono, Momoka Ijichi, Takato Tsuboguchi and Kentaro Yasui
Materials 2025, 18(17), 4191; https://doi.org/10.3390/ma18174191 - 6 Sep 2025
Viewed by 642
Abstract
This study addresses the problem of pumice deposits in the southern Kyushu region, which can cause landslides during heavy rainfall. To reduce this hazard, it is important to expand pumice applications and promote its use before disaster events occur. Among construction materials, this [...] Read more.
This study addresses the problem of pumice deposits in the southern Kyushu region, which can cause landslides during heavy rainfall. To reduce this hazard, it is important to expand pumice applications and promote its use before disaster events occur. Among construction materials, this study explores the possibility of using pumice as a concrete aggregate, considering the global shortage of natural aggregates. Because of the low strength and difficulty of use, pumice must be fired to improve its properties. In our experiment, it was fired at 1000 or 1100 °C, and the performance of the resulting concretes was compared. Concrete incorporating pumice fired at 1100 °C achieved a maximum compressive strength of 54.6 N/mm2 with an increase in the amount of cement, whereas concrete with pumice fired at 1000 °C remained within the 20–24 N/mm2 range even when the amount of cement was increased. This difference arises because pumice has a lower strength than the cement paste, leading to material failure. Furthermore, freeze–thaw tests showed that concrete made with pumice fired at 1100 °C was resistant to frost damage. These results suggest that pumice fired at 1100 °C has an excellent potential as a sustainable building material. Full article
(This article belongs to the Special Issue Advances in Sustainable Construction Materials, Third Edition)
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32 pages, 9333 KB  
Review
BaTiO3-Based Electrocaloric Materials—Recent Progresses and Perspective
by Yi Tang, Xiang Niu, Yuleng Jiang, Junxi Cao, Junying Lai, Houzhu He, Jianpeng Chen, Xiaodong Jian and Sheng-Guo Lu
Materials 2025, 18(17), 4190; https://doi.org/10.3390/ma18174190 - 6 Sep 2025
Viewed by 608
Abstract
BaTiO3 (BT)-based lead-free ceramics are regarded as highly promising candidates for solid-state electrocaloric (EC) cooling devices due to their large spontaneous polarizations, shiftable Curie temperatures, and environmental friendliness. This review summarizes recent progresses in the design and optimization of BT-based EC ceramics. [...] Read more.
BaTiO3 (BT)-based lead-free ceramics are regarded as highly promising candidates for solid-state electrocaloric (EC) cooling devices due to their large spontaneous polarizations, shiftable Curie temperatures, and environmental friendliness. This review summarizes recent progresses in the design and optimization of BT-based EC ceramics. Key aspects include thermodynamic principles of the EC effect (ECE); structural phase transitions; and strategies such as constructing relaxor ferroelectrics, multi-phase coexistence, etc. Finally, future research directions are proposed, including the exploration of local microstructural evolution, polarization flip mechanisms, and bridging material design and device integration. This work aims to provide insights into the development of high-performance BT-based materials for solid-state cooling devices. Full article
(This article belongs to the Section Advanced and Functional Ceramics and Glasses)
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