Materials

19 pages, 5803 KB

Open AccessArticle

Formation and Antibacterial Mechanisms of Micro-Arc Oxidation Coatings on Ta2 Pure Titanium by Doping with Cu₂O Nanoparticles

by Xumin Zhang, Huie Hu, Ansheng Cheng and Hao Wang

Materials 2026, 19(20), 4273; https://doi.org/10.3390/ma19204273 - 9 Oct 2026

Abstract

Cu₂O nanoparticles (0–4 g/L) were incorporated into the electrolyte to fabricate coatings on TA2 pure titanium via micro-arc oxidation. The effects of different Cu₂O nanoparticle concentrations on the microstructure, antibacterial performance, formation, and antibacterial mechanisms of the coatings were [...] Read more.

Cu₂O nanoparticles (0–4 g/L) were incorporated into the electrolyte to fabricate coatings on TA2 pure titanium via micro-arc oxidation. The effects of different Cu₂O nanoparticle concentrations on the microstructure, antibacterial performance, formation, and antibacterial mechanisms of the coatings were investigated. Microstructural characterization indicated that Cu₂O nanoparticles were incorporated into the coating through the combined action of electrophoretic forces and micro-discharges. At 4 g/L Cu₂O, the incorporation of Cu₂O nanoparticles shifted from uniform incorporation to particle aggregation. Compared with coatings fabricated using 1 and 2 g/L Cu₂O nanoparticles, those fabricated using 3 and 4 g/L exhibited superior antibacterial efficacy. Copper ion release was the primary antibacterial mechanism. Micro-arc oxidation coatings modified with 3 g/L Cu₂O nanoparticles achieved the best compromise between microstructural uniformity and antibacterial performance among the tested concentrations. Full article

(This article belongs to the Section Thin Films and Interfaces)

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45 pages, 10919 KB

Open AccessArticle

Metaheuristic-Driven Machine Learning for Best-Observed Feasible Weight Estimation of Braced Steel High-Rise Frames

by Betül Üstüner, Aybike Özyüksel Çiftçioğlu, Erkan Doğan and Ali Mardani

Materials 2026, 19(20), 4272; https://doi.org/10.3390/ma19204272 - 9 Oct 2026

Abstract

Preliminary selection of bracing systems in high-rise steel buildings requires comparing many configurations, each demanding computationally intensive minimum-weight design. This study uses machine learning to estimate the best-observed feasible weight directly from building-level configuration parameters. A full factorial dataset of 45 configurations covered [...] Read more.

Preliminary selection of bracing systems in high-rise steel buildings requires comparing many configurations, each demanding computationally intensive minimum-weight design. This study uses machine learning to estimate the best-observed feasible weight directly from building-level configuration parameters. A full factorial dataset of 45 configurations covered three storey numbers (17, 24, and 30), three bracing types (V, X, and K), and five brace-placement layouts. Each configuration was optimized in a coupled SAP2000–MATLAB procedure with Particle Swarm, Grey Wolf, Honey Badger, and Aquila optimization (180 runs in total); no single algorithm was best for every configuration. Mean weight increased from 2537 kN at 17 storeys to 7103 kN at 30 storeys. X-bracing gave the highest mean weight at all heights and K-bracing the lowest at 17 and 24 storeys, whereas V- and K-bracing differed by only 2.4% at 30 storeys. Bracing type changed the mean weight by up to about 30%, and brace placement by about 10–15%. Among six regression models, Ridge achieved the highest mean five-fold cross-validated R² (0.914; 0.904 over 1000 repeated partitions), while Random Forest gave the lowest RMSE (511.7 kN); in leave-one-out prediction, Ridge ordered 90.3% of configuration pairs correctly. The resulting Ridge equation offers an interpretable screening tool within the investigated design domain. Full article

(This article belongs to the Special Issue Artificial Intelligence in Advanced Manufacturing and Materials Processing)

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19 pages, 1024 KB

Open AccessArticle

Enhancement of Conversion Efficiency of B(In)GaAs Solar Cells: A Simulation and Numerical Investigation

by Dalanda Slimi, Faouzi Saidi, Abdelhamid Helali, Abdelkader Aissat, Mohamed Houcine Dhaou, Mohamed Alaaedine Madani and Demir Ilkay

Materials 2026, 19(20), 4271; https://doi.org/10.3390/ma19204271 - 9 Oct 2026

Abstract

This study focuses on the modeling and optimization of B_xGa_1−xAs/In_yGa_1−yAs double-junction photovoltaic cells and GaAs/B_xIn_yGa_1−x−yAs quantum well pin cells. It relies on Silvaco Atlas software 2.10.26R to simulate these [...] Read more.

This study focuses on the modeling and optimization of B_xGa_1−xAs/In_yGa_1−yAs double-junction photovoltaic cells and GaAs/B_xIn_yGa_1−x−yAs quantum well pin cells. It relies on Silvaco Atlas software 2.10.26R to simulate these structures, considering the desired number of QWs or the constant percentage of boron and indium in the III-V-based alloys of B_xGa_1−xAs, In_yGa_1−yAs, and B_xIn_yGa_1−x−yAs. The B_xIn_yGa_1−x−yAs material finds its application in the fabrication of quantum wells incorporated into the intrinsic GaAs-type absorber layer. This absorber layer is positioned between the heavily doped base and the emitting regions, in order to generate a uniform field that allows all photogenerated carriers to escape from the QWs. As part of the modeling, a comparison was made between a 40-layer GaAs/B_xIn_yGa_1−x−yAs quantum well solar cell and a standard GaAs solar cell. This analysis revealed an increase in the conversion efficiency of the simulation results from 22.66% to 31.73%. As a result, the integration of quantum wells into the structure of solar cells seems promising to optimize their performance. The optimized B_xGa_1−xAs/In_yGa_1−yAs tandem structure demonstrated a short-circuit current density of 17.50 mA/cm², an open-circuit voltage of 1.99 V, a fill factor of 87.29%, and a conversion efficiency of 30.40% under AM1.5G illumination at 300 K. Full article

(This article belongs to the Section Optical and Photonic Materials)

23 pages, 1044 KB

Open AccessReview

Opportunities and Challenges for Next-Generation Cementitious Materials Under Rising Demand

by Anastasia N. Aday, Fabian B. Rodriguez and John T. Kevern

Materials 2026, 19(20), 4270; https://doi.org/10.3390/ma19204270 - 9 Oct 2026

Abstract

The cement and concrete industry now has access to a wider variety of cementitious material options than at any point in its history, yet only a subset of these materials are deployed at scale. Current construction practices are evolving from traditional cements towards [...] Read more.

The cement and concrete industry now has access to a wider variety of cementitious material options than at any point in its history, yet only a subset of these materials are deployed at scale. Current construction practices are evolving from traditional cements towards Portland limestone cements and blended systems such as Limestone Calcined Clays (LC³), alongside expanded use of established and emerging supplementary cementitious materials (SCMs) and alternative SCMs (ASCMs). Industrial by-products, including changing fly ash and slag streams, electric arc furnace slag, reclaimed ash, waste glass, mine tailings, and recycled concrete fines for enhanced carbonation are emerging as feedstock options to supplement demand for SCMs. This review provides a materials-centric synthesis of cementitious material options that could contribute to the U.S. cement and concrete supply through approximately 2035–2040. The materials are organized into two broad readiness classes: readily available materials and blended systems with existing feedstock streams and credible near-term adoption pathways, and emerging material concepts for which processing, logistics, or qualification frameworks are not yet sufficiently mature for industry-wide deployment. Readily available options include calcined clays, limestone calcined clay cement (LC³) systems, ground lightweight aggregate fines, and reclaimed ash, while emerging options include mine tailings, recycled concrete fines, electric arc furnace slag, waste glass pozzolans, carbonation-cured binders, and biocementation approaches. For each material family, the review evaluates availability, technical performance, and standards and adoption status, including feedstock volumes and geographic distribution, processing requirements, reported strength and durability performance, and compatibility with existing production and construction practices. Across both readiness classes, broader deployment will require robust reactivity and performance test methods, long-term durability and field-performance evidence, supply-chain readiness, and staged qualification and specification pathways. The review concludes by identifying practical priorities for researchers, standards bodies, and major buyers seeking to advance next-generation cementitious materials from laboratory evaluation and demonstration toward routine use. Full article

(This article belongs to the Special Issue Preparation and Properties of New Cementitious Materials (Third Edition))

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48 pages, 157402 KB

Open AccessReview

Modulation of Soft Magnetic Properties in Fe-Based Amorphous and Nanocrystalline Alloys for Power Transformers: A Review

by Jiashuai Ge, Xinjiang Zhang, Cailiu Yin, Zhao Lu and Bin Li

Materials 2026, 19(20), 4269; https://doi.org/10.3390/ma19204269 - 9 Oct 2026

Abstract

Fe-based amorphous and nanocrystalline alloys are essential core materials for high-efficiency distribution transformers, high-frequency transformers, and power electronic transformers, owing to their high saturation magnetic flux density (B_s), low coercivity (H_c), low core loss, and excellent high-frequency response. This [...] Read more.

Fe-based amorphous and nanocrystalline alloys are essential core materials for high-efficiency distribution transformers, high-frequency transformers, and power electronic transformers, owing to their high saturation magnetic flux density (B_s), low coercivity (H_c), low core loss, and excellent high-frequency response. This review summarizes recent progress in the modulation of soft magnetic properties, covering composition design, heat treatments, structural engineering, and transformer applications. For compositional design, a central issue is how to achieve high B_s while retaining sufficient Glass-forming ability (GFA), and appropriate additions of metalloid and transition-metal elements provide an effective route to this balance. Conventional isothermal, stress, magnetic-field, and rapid annealing processes enable structural relaxation, nanocrystallization, and anisotropy modulation. Ultrafine nanocrystals, amorphous/nanocrystalline transitional structures, and gradient and multilayer structures further improve overall performance through grain refinement, interface engineering, and domain optimization. Key engineering challenges include continuous ribbon casting, heat-treatment uniformity, winding-induced residual stress, and practical operating conditions. Future advances require the integration of in situ characterization, multiscale modeling, and machine learning, alongside advances in continuous heat treatment and low-stress manufacturing, to facilitate wider application in transformers. Full article

(This article belongs to the Section Metals and Alloys)

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20 pages, 11715 KB

Open AccessArticle

A Theoretical Model for Structural Health Monitoring of the Thermal-Mechanical Behaviour of Plates Under Combined Laser Irradiation and Airflow

by Qi Pu, Xiaodong Jia, Yizhuo Gui, Shaozun Hong, Te Ma, Hongwei Song and Cheng Qiu

Materials 2026, 19(20), 4268; https://doi.org/10.3390/ma19204268 - 9 Oct 2026

Abstract

Laser irradiation, as a high-energy input, induces a rapid temperature rise on a structure’s surface, resulting in a localized stress concentration, which is one of the key elements in catastrophic failure. Accurate structural health monitoring of plates should take stress distribution into account. [...] Read more.

Laser irradiation, as a high-energy input, induces a rapid temperature rise on a structure’s surface, resulting in a localized stress concentration, which is one of the key elements in catastrophic failure. Accurate structural health monitoring of plates should take stress distribution into account. In this paper, we present a theoretical model for determining the stress state of a plate under combined laser radiation and airflow, using temperature values from several discrete measurement points as input. First, a fitting function was proposed based on data-driven thermal analysis, which is utilized to acquire the temperature distribution on the whole surface. The stress state near the area of the laser radiation was then calculated using a theoretical model based on the elasticity theory of an axis-symmetric problem. With the incorporation of the data-driven method, the model is then extended from a baseline analytical model to account for three-dimensional heat-conduction effects and the nonlinear temperature dependence of thermophysical properties. The effectiveness and precision of the proposed model were verified by coupled thermal-mechanical simulations. The current work can provide substantial support for developing a structural health monitoring system for aerospace structures exposed to laser radiation. Full article

(This article belongs to the Special Issue AI-Driven Discovery in Materials and Chemistry)

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18 pages, 22415 KB

Open AccessArticle

The Impact of Intra-Burst Energy Distribution on Volume Removal and Surface Quality in Laser Ablation of Stainless Steels Using Ultrashort Pulsed Lasers

by Dirk Obergfell, Flavio Soldera, Bahman Azarhoushang and Andrés Fabián Lasagni

Materials 2026, 19(20), 4267; https://doi.org/10.3390/ma19204267 - 9 Oct 2026

Abstract

Stainless-steel alloys are widely used in applications requiring high corrosion resistance and mechanical durability. For embossing tool fabrication, high-volume material removal with high surface quality is essential. Laser-based ablation offers an alternative to micromilling by enabling material removal without mechanical contact, thereby eliminating [...] Read more.

Stainless-steel alloys are widely used in applications requiring high corrosion resistance and mechanical durability. For embossing tool fabrication, high-volume material removal with high surface quality is essential. Laser-based ablation offers an alternative to micromilling by enabling material removal without mechanical contact, thereby eliminating cutting tool wear and facilitating the fabrication of complex geometries. However, productivity must be increased without degrading surface quality, which plays a critical role in embossing tool wear behavior and lifetime. This study investigates the ablation efficiency and surface quality of AISI 304, AISI 420, and AISI 316Ti stainless steels using a 250 fs pulsed laser. Different fluence levels and burst configurations, including MHz, GHz, and Bi-burst, are examined, focusing on the influence of intra-burst energy distribution on material removal rate and surface quality. Surface morphology and roughness are characterized by optical, confocal, and scanning electron microscopy. The results show that removal rate, ablation efficiency, and surface roughness are strongly affected by the intra-burst energy distribution (positive or negative slopes). The highest removal rate of 5.74 mm³ min⁻¹ was obtained using MHz bursts, whereas GHz bursts enabled surface roughness values Sa below 1 µm. Negative energy slopes generally reduced surface roughness in isolated MHz and GHz burst modes, while Bi-burst processing provided smooth surfaces over a wider range of slope conditions. All alloys followed similar trends, with AISI 316Ti exhibiting greater susceptibility to microhole formation under certain burst conditions. Full article

(This article belongs to the Special Issue Laser Manufacturing and Material Modification)

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26 pages, 51250 KB

Open AccessArticle

Interfacial Microstructure and Tensile–Shear Properties of AA1060/SUS304 Dissimilar Sheet Joints Fabricated by Uniform-Pressure Electromagnetic Pulse Welding

by Zhisong Fan, Ying Huang, Shu Zhang, Jianghua Deng, Hanwei Ning and Minjie Huang

Materials 2026, 19(20), 4266; https://doi.org/10.3390/ma19204266 - 9 Oct 2026

Abstract

Compared with single-turn coil magnetic pulse welding, magnetic pulse welding using a uniform-pressure electromagnetic actuator (UP-EMPW) can provide a larger area of uniform pressure and address issues such as low energy utilization efficiency and short coil lifespan. In this work, AA1060 aluminum sheets [...] Read more.

Compared with single-turn coil magnetic pulse welding, magnetic pulse welding using a uniform-pressure electromagnetic actuator (UP-EMPW) can provide a larger area of uniform pressure and address issues such as low energy utilization efficiency and short coil lifespan. In this work, AA1060 aluminum sheets were joined to SUS304 stainless steel sheets by UP-EMPW. The effects of discharge voltage and initial gap on the interfacial microstructure and mechanical properties of the joints were investigated by optical microscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and tensile shear tests. Two distinct interface morphologies were observed: wavy interfaces and straight interfaces. Their formation was influenced by the combined effects of discharge voltage and initial gap. Microhardness measurements across the weld interface were further conducted to evaluate the local mechanical response and to help interpret the strengthening mechanisms associated with different interfacial features. The results showed that straight interfaces without a transition zone exhibited hardness values between those of the base materials, whereas wavy interfaces with a transition zone showed higher hardness values than both parent materials. Although these hardness data should be considered qualitative because of the limited indentation spacing, the overall trend suggests a stronger local strengthening effect at the wavy interface. The tensile shear tests indicated that the maximum load first increased and then decreased with increasing discharge voltage or initial gap. The highest joint performance within the investigated range was obtained at a discharge voltage of 9 kV and an initial gap of 1.5 mm, with a mean maximum tensile–shear load of 3288 ± 256 N and failure in the aluminum base material. The improved mechanical performance appeared to result from the combined effects of mechanical interlocking and metallurgical bonding associated with the wavy interface and transition zone. Fracture surface analysis further showed that base material fractures exhibited mixed ductile and brittle features, whereas pull-out failures were characterized by localized bonding and limited interfacial bonding. Full article

(This article belongs to the Special Issue Artificial Intelligence Applied to Metal Forming and Manufacturing)

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5 pages, 171 KB

Open AccessEditorial

Incorporating Advanced New or Recycled Materials in Reinforced Concrete Structures

by Ayman El-Zohairy and Antonio Caggiano

Materials 2026, 19(20), 4265; https://doi.org/10.3390/ma19204265 - 9 Oct 2026

Abstract

Reinforced concrete continues to be one of the most widely used structural materials worldwide because of its versatility, availability, durability, and ability to accommodate a range of structural forms and loading conditions [...] Full article

(This article belongs to the Special Issue Incorporating Advanced New or Recycled Materials in Reinforced Concrete Structures)

19 pages, 4984 KB

Open AccessArticle

Analysis of Interfacial Properties and Mechanical Mechanisms of Expansion-Type Bolts

by Yixiao Wang, Wei Zhao, Pengyu Zhu and Yuliang Lin

Materials 2026, 19(20), 4264; https://doi.org/10.3390/ma19204264 - 9 Oct 2026

Abstract

As mining operations extend to greater depths, the high in-situ stresses and intense disturbances associated with deep mining present significant challenges for mining operations, including fractured rock masses, poor stability, susceptibility to water-induced softening and deformation, and difficulties in ground support. As one [...] Read more.

As mining operations extend to greater depths, the high in-situ stresses and intense disturbances associated with deep mining present significant challenges for mining operations, including fractured rock masses, poor stability, susceptibility to water-induced softening and deformation, and difficulties in ground support. As one of the most critical support components in tunnels and mine roadways, the anchorage mechanism of bolts at the bolt-surrounding rock interface in deep fractured surrounding rock remains unclear. To gain deeper insight into the anchorage mechanism and failure evolution of the bolt-surrounding rock interface under deep surrounding rock conditions, this study conducts similar bolt pull-out tests to investigate the anchorage performance of the bolt-surrounding rock interface during pull-out under multiple experimental factors, and analyzes the mechanical properties, response stages, and failure characteristics of the anchorage interface using multiple evaluation indices. The results show that: (1) the anchorage length, the confining pressure, and the material strength act on the anchorage performance through distinct mechanisms; (2) the introduction of expansion points on the bolt surface alters the interfacial load-transfer path and markedly improves the anchorage performance, albeit with a marginal effect; (3) based on the measured load-slip responses, the pull-out process is interpreted as six consecutive stages, whose characteristics differ notably between conventional and expansion-type bolts. Full article

(This article belongs to the Special Issue Advanced Geomaterials and Reinforced Structures (3rd Edition))

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20 pages, 4720 KB

Open AccessArticle

Dynamic Compressive Behavior and Internal Damage Evolution of Polypropylene Fiber-Reinforced Alkali-Activated Slag Geopolymer Mortar

by Binghui Cui, Yanzhu Liu and Liang Wang

Materials 2026, 19(20), 4263; https://doi.org/10.3390/ma19204263 - 9 Oct 2026

Abstract

Ordinary Portland cement (OPC) production is energy- and carbon-intensive, which has motivated the development of more sustainable alternatives such as alkali-activated materials, including granulated blast furnace slag (GBFS) geopolymer mortar. Geopolymer mortar, however, is brittle, has low tensile strength and poor crack resistance, [...] Read more.

Ordinary Portland cement (OPC) production is energy- and carbon-intensive, which has motivated the development of more sustainable alternatives such as alkali-activated materials, including granulated blast furnace slag (GBFS) geopolymer mortar. Geopolymer mortar, however, is brittle, has low tensile strength and poor crack resistance, and its damage evolution under dynamic impact remains insufficiently understood. Here we show that polypropylene fiber (PPF) reinforcement substantially improves the dynamic impact resistance of GBFS-based geopolymer mortar with only a limited effect on static compressive strength. Mortars with PPF volume contents of 0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% were prepared at a water-to-binder ratio of 0.55. Flowability, static compressive strength, and dynamic mechanical properties were evaluated using a split Hopkinson pressure bar at strain rates of 50 s⁻¹–130 s⁻¹, and failure morphology was examined through SEM and CT analysis. Increasing PPF content reduced flowability from 253 mm to 224 mm at 1.0% but had little effect on static strength. Dynamic compressive strength, dynamic increase factor (DIF), and ultimate toughness increased with both strain rate and fiber content. The 1.0% PPF mortar reached a maximum DIF of 2.129 and a 99.3% increase in impact toughness. CT analysis further showed that PPF suppressed the formation of large internal voids: approximately 31, 2, and 5 voids larger than 4 mm³ were detected in the 0.6%, 0.8%, and 1.0% PPF specimens, respectively. The improvement is attributed to fiber bridging and pull-out, which consume impact energy and inhibit crack initiation and propagation. These results indicate that, within the tested range, a PPF content of 1.0% is effective for impact-resistant geopolymer mortar. Full article

(This article belongs to the Special Issue Research on Alkali-Activated Materials (Third Edition))

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16 pages, 8170 KB

Open AccessArticle

Enhanced Dispersion and Structural Homogeneity in LDPE/Bi₂O₃/B₄C Composites via Cryogenic Ball Milling with Binary-Sized Grinding Media

by Vyacheslav Ivanovich Pavlenko, Roman Nikolaevich Yastrebinsky, Natalia Igorevna Cherkashina, Andrey Ivanovich Gorodov and Dmitry Sergeevich Romanyuk

Materials 2026, 19(20), 4262; https://doi.org/10.3390/ma19204262 - 9 Oct 2026

Abstract

The study investigated the effect of a dense two-fraction ball load on the efficiency of cryogenic dispersion and the structural uniformity of polymer composite materials based on low-density polyethylene (LDPE) filled with bismuth oxide (Bi₂O₃) and boron carbide (B [...] Read more.

The study investigated the effect of a dense two-fraction ball load on the efficiency of cryogenic dispersion and the structural uniformity of polymer composite materials based on low-density polyethylene (LDPE) filled with bismuth oxide (Bi₂O₃) and boron carbide (B₄C). A comparative analysis of two grinding modes—mono-fraction and binary (dense) loading of grinding media—showed that using binary loading reduces the modal diameter of LDPE particles from 19.1 to 13.4 μm, and the number of Bi₂O₃ particles smaller than 5 μm increases by 1.25 times. Using XRF and IR spectroscopy, it was established that cryogenic grinding is accompanied by mechanochemical degradation of polyethylene, resulting in the formation of hydroxyl and carbonyl groups, which improve the interfacial interaction between the polymer and inorganic phases of the composite. At the same time, during the subsequent thermopressing of the product, thermal relaxation of the polymer structure occurs and unstable oxidized fragments are eliminated. Energy-dispersive X-ray mapping confirmed a more uniform filler distribution with binary loading: the proportion of element localization regions exceeding 500 μm² decreased for B (0.46 → 0.24), C (0.85 → 0.74), and Bi (0.36 → 0.31). Ultrasonic testing showed a ~3.5% increase in sound velocity (from 2038 to 2110 m/s) and an increase in elastic modulus from 2.36 to 3.34 MPa, indicating improved structural homogeneity and elastic properties. This is the first application of binary-sized grinding media to cryogenic milling of polymer composites. The results demonstrate the potential of cryogenic mechanical activation with a dense two-fraction ball charge for producing highly homogeneous polymer composite materials without organic solvents. Full article

(This article belongs to the Special Issue Advanced Polymer Composites for Sustainable Technologies: Synthesis, Characterization, and Performance—Second Edition)

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25 pages, 31155 KB

Open AccessArticle

Preparation of High-Purity Vanadium Metal by Iodide Refining Based on Numerical Simulation Using SIMPLE Algorithm

by Zhifang Hu, Bowen Gao, Honglin Jiang, Qidong Zhang and Yanxi Yin

Materials 2026, 19(19), 4261; https://doi.org/10.3390/ma19194261 - 8 Oct 2026

Abstract

In this study, the iodide refining of high-purity vanadium metal was investigated experimentally and by two-dimensional numerical simulations based on the SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) algorithm. The effects of system temperature, K values (characterizing the deposition filament temperature), initial iodine amount, [...] Read more.

In this study, the iodide refining of high-purity vanadium metal was investigated experimentally and by two-dimensional numerical simulations based on the SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) algorithm. The effects of system temperature, K values (characterizing the deposition filament temperature), initial iodine amount, and raw material packing configuration on the deposition rate, crystal morphology, and mass transport were studied in a custom-built iodide apparatus. The experimental results showed that the deposition rate exhibited a bell-shaped dependence on the source temperature. The optimal source temperature and optimal K value were 1123–1173 K and 40–50, respectively, at which the average deposition rate reached its peak. Both the average deposition rate and the average reaction time increased slightly with increasing initial iodine amount, but the increases were limited. Full loading of the raw material yielded crystal rods of uniform size. Vanadium crystal rods with a diameter of approximately 20 mm were obtained after refining. The metallic impurities Fe, Cr, Al, and Si were reduced to 0.025–0.033 wt.%, <0.001 wt.%, <0.001 wt.%, and <0.002 wt.%, respectively, while the interstitial impurities O, C, and N were reduced to <0.01 wt.%, <0.002 wt.%, and <0.002 wt.%, respectively, indicating that iodide refining can effectively reduce the contents of both interstitial and metallic impurities in vanadium metal. Numerical simulation results showed that the mass transport rate decreased monotonically with increasing total pressure, increased with rising temperature owing to the enhanced VI₂ partial-pressure difference, and decreased with increasing transport distance. The flow pattern transitioned from pure diffusion/advection at 300 Pa to transitional vortices at 1000 Pa, and finally to fully developed recirculation at 3000 Pa. The simulation results are qualitatively consistent with the experimental observations, providing a theoretical basis for process optimization. To further improve the purity and scale-up potential of the process, it is necessary to conduct more in-depth research, including the development of fully coupled models that incorporate gas-phase dissociation, non-equilibrium surface kinetics, and composition-dependent mixture properties, as well as three-dimensional simulations and reactor material optimization. Full article

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

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14 pages, 1569 KB

Open AccessArticle

Nanostructuration of SmCo₅ Magnets by Spark Plasma Sintering: Optimization of Magnetic Properties

by Nicolas Albar, Frédéric Adamski, Sulivan Kuttler, Pierre Sallot and Claude Estournès

Materials 2026, 19(19), 4260; https://doi.org/10.3390/ma19194260 - 8 Oct 2026

Abstract

In the context of current climate issues and environmental constraints, green and renewable energies have experienced considerable growth in recent decades. Thus, there has been a renewed interest in the development of electric machines. To achieve this, the optimization of mass saving, volume [...] Read more.

In the context of current climate issues and environmental constraints, green and renewable energies have experienced considerable growth in recent decades. Thus, there has been a renewed interest in the development of electric machines. To achieve this, the optimization of mass saving, volume and magnetic performance in the development of these machines must accelerate and be implemented industrially, particularly in the aeronautical field. The aircraft of the future will therefore require the use of electric machines with very high power densities and efficiencies. To achieve these objectives, one of the essential components to improve is the permanent magnet, and in particular its magnetic properties (increases in coercive field, residual magnetization and specific energy density). These magnets are likely to operate at temperatures above 200 °C. In this context, hard ferromagnetic magnets seem to be the most appropriate. SmCo₅ magnets have a Curie temperature between 720 and 920 °C. In this work we show the impact of grinding time on the magnetic properties of these SPS-treated magnets. This method allows the sintering SmCo₅ magnets while limiting their oxidation and their grain growth. By optimizing the grinding parameters, we obtain magnets with a coercive field of the order of 18,800 Oe. The novelty of this study lies in the optimization of EBSD (Electron Backscatter Diffraction) image analysis using the NLPAR (Non-Local Pattern Averaging Reconstruction) method, combined with advanced image correlation techniques. This approach enabled the precise determination of a grain size distribution centered around 50 nm, offering new perspectives on microstructural control and the enhancement of magnetic performance in SmCo₅ magnets. Full article

(This article belongs to the Special Issue Advances in Characterization, Modeling and Design of Magnetic Materials)

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11 pages, 206 KB

Open AccessEditorial

Construction and Building Materials: Highlights from the 2025 Editor’s Choice Collection

by Marco Corradi

Materials 2026, 19(19), 4259; https://doi.org/10.3390/ma19194259 - 8 Oct 2026

Abstract

The construction sector is undergoing a significant transformation driven by the combined demands of climate change mitigation, resource efficiency, infrastructure resilience and the need to adapt to rapidly changing societal and technological requirements [...] Full article

(This article belongs to the Section Construction and Building Materials)

18 pages, 1131 KB

Open AccessArticle

Magnetic Properties of Fe-Ni-Cr Alloy Coatings Processed via High-Velocity Oxygen-Fuel Spraying

by Xiqiang Ma, Shuai Han, Dongliang Jin, Jinpeng Li and Nan Guo

Materials 2026, 19(19), 4258; https://doi.org/10.3390/ma19194258 - 8 Oct 2026

Abstract

In this work, soft magnetic coatings were fabricated from Fe-Ni-Cr (1J38) alloy powders via high-velocity oxygen-fuel (HVOF) spraying. The microstructural features and intrinsic magnetic properties were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and a background signal stripping algorithm. Furthermore, the [...] Read more.

In this work, soft magnetic coatings were fabricated from Fe-Ni-Cr (1J38) alloy powders via high-velocity oxygen-fuel (HVOF) spraying. The microstructural features and intrinsic magnetic properties were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and a background signal stripping algorithm. Furthermore, the microstructural defects and magnetic degradation characteristics of coatings with varying thicknesses were comparatively analyzed. The results indicate that while the HVOF deposits exhibit exceptional density, the rapid quenching process inevitably induces oxygen-rich inter-splat boundary networks and residual stresses within the coatings. XRD analysis reveals no significant macroscopic oxidation or phase transformation during deposition, demonstrating a high-fidelity retention of the original face-centered cubic (FCC) lattice structure of the feedstock alloy. Magnetic measurements, upon the precise elimination of substrate background interference, reveal a distinct wasp-waisted magnetization distortion at low magnetic fields. This phenomenon can be attributed to the asynchronous magnetization response between the easily reversed, unoxidized soft-magnetic splat cores and the high-barrier boundary pinning networks (composed of inter-splat oxide interlayers and localized high-stress concentrations) within the coating. Compared to the thicker deposits (0.5 mm), the thinner coatings (0.3 mm) exhibit superior magnetic performance, characterized by a lower intrinsic coercivity. This degradation in thicker coatings is ascribed to the substantial accumulation of macroscopic residual stresses during deposition, which exert a stronger pinning effect on magnetic domain wall motion. Full article

(This article belongs to the Special Issue Magnetic Materials and Their Applications in Quantum Devices)

24 pages, 39109 KB

Open AccessArticle

Effect of Induction Hardening Conditions on Effective Case Depth, Microstructure, and Tribological Properties of C50 Steel Inner Races in Constant-Velocity Joints

by Krzysztof Włoch, Sylwia Wencel and Piotr Szablewski

Materials 2026, 19(19), 4257; https://doi.org/10.3390/ma19194257 - 8 Oct 2026

Abstract

Increasing torque density and dynamic loading conditions in modern automotive drivetrains, particularly in electric vehicles, impose stringent requirements on the surface integrity of constant-velocity (CV) joint components. Induction hardening of medium-carbon steels is a potential alternative to conventional carburizing; however, the influence of [...] Read more.

Increasing torque density and dynamic loading conditions in modern automotive drivetrains, particularly in electric vehicles, impose stringent requirements on the surface integrity of constant-velocity (CV) joint components. Induction hardening of medium-carbon steels is a potential alternative to conventional carburizing; however, the influence of hardening strategy on hardened layer characteristics and functional performance remains insufficiently explored for CV joint inner races with complex geometry. In this study, industrial-scale induction hardening trials were performed on C50 steel inner races using two processing strategies: single-shot and scanning. An industrial-scale comparative study was conducted to evaluate hardness distribution, effective case depth (EDH₅₀₀HV), microstructure, and tribological behavior under representative single-shot and scanning processing conditions. Hardness reached the target range of 653–772 HV1 (≈58–63 HRC) with both strategies. However, clear differences in effective case depth and microstructural homogeneity were observed. The scanning strategy showed a more uniform near-surface hardness distribution and lower variability in effective case depth compared with single-shot hardening. Tribological testing under dry reciprocating sliding conditions revealed comparable friction coefficients, while variations in wear scar morphology were associated with differences in microstructural continuity and transformation uniformity. The results establish a relationship between induction energy input, phase transformation behavior, case depth control, and functional wear response, providing an industrially applicable framework for process optimization of C50 steel CV joint inner races. Full article

(This article belongs to the Topic Production, Processing, Microstructure and Functional Properties in Materials Engineering)

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15 pages, 14393 KB

Open AccessArticle

Study on the Effect of Nanocellulose Type and Dosage on the Stability Performance of Cemented Backfill with Lithium Tailings

by Cong Xiao, Qing Deng, Xuefangzi Dong, Shibin Zhang and Daopei Zhu

Materials 2026, 19(19), 4256; https://doi.org/10.3390/ma19194256 - 8 Oct 2026

Abstract

The large-scale accumulation of lithium-feldspar tailings generated during lithium ore beneficiation poses environmental and resource-utilization challenges. Cemented lithium-feldspar tailings backfill (CLFTB) provides an effective approach for their underground disposal and resource utilization; however, its mechanical performance remains a key concern. Nanocellulose, with its [...] Read more.

The large-scale accumulation of lithium-feldspar tailings generated during lithium ore beneficiation poses environmental and resource-utilization challenges. Cemented lithium-feldspar tailings backfill (CLFTB) provides an effective approach for their underground disposal and resource utilization; however, its mechanical performance remains a key concern. Nanocellulose, with its high specific surface area and fibrillar structure, has potential for improving the stability and mechanical properties of cementitious tailings backfill. This study investigates the effects of nanocellulose type and dosage on the macro- and micro-scale performance of CLFTB. Three nanocellulose types, namely carboxylated cellulose nanofibrils (CNFs), cellulose nanocrystals (CNCs), and microfibrillated cellulose (MFC), were incorporated at dosages of 0.6–1.5 kg/m³. Uniaxial compressive-strength tests and microstructural analyses were conducted to evaluate their effects. The results showed that all nanocellulose-modified groups exhibited higher compressive strength than the control group. The optimum dosage was 0.9 kg/m³, while MFC provided the greatest strength enhancement among the three nanocellulose types. Nanocellulose incorporation also altered the failure behavior and mitigated crack propagation. EDS analysis further revealed differences in the local elemental characteristics of the modified specimens. Overall, the results demonstrate that nanocellulose, particularly MFC, can effectively enhance the mechanical performance and stability of CLFTB. Full article

(This article belongs to the Special Issue Low-Carbon Cementitious Materials and Sustainable Strengthening Strategies)

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11 pages, 1722 KB

Open AccessArticle

Concentration-Dependent Pore Morphology in Cellulose Acetate Coatings for Enhanced Radiative Cooling

by Haopeng Yu, Rui Yang, Xiaohua Feng, Pengyu Li and Hua Li

Materials 2026, 19(19), 4255; https://doi.org/10.3390/ma19194255 - 8 Oct 2026

Abstract

This study employs the non-solvent-induced phase separation (NIPS) method to fabricate porous cellulose acetate (CA) coatings. By optimizing the concentration of CA and N, N-dimethylacetamide (DMAC), the pore structure and size of the coatings are effectively controlled. The influence of homogeneous [...] Read more.

This study employs the non-solvent-induced phase separation (NIPS) method to fabricate porous cellulose acetate (CA) coatings. By optimizing the concentration of CA and N, N-dimethylacetamide (DMAC), the pore structure and size of the coatings are effectively controlled. The influence of homogeneous solution concentration on the optical properties of CA coatings is explored, and the relationship between the microstructure of the coatings and their radiative cooling performance is analyzed in depth. A self-assembled radiative cooling device is used to experimentally evaluate the cooling effect of the porous CA coatings. The results show that when the CA concentration reaches 15 wt%, the coating exhibits an ordered transition from irregular large pores to well-defined finger-like pores and then to sponge-like pores, achieving the optimal radiative cooling performance. At this concentration, the coating achieves a high solar reflectance (0.3–2.5 μm) of 96.56% and an emissivity of 0.96 in the atmospheric transparency window (8–13 μm). Compared to the uncoated substrate, the temperature difference reaches 18.88 °C, and the cooling effect relative to the ambient temperature is 2.6 °C, demonstrating excellent radiative cooling performance. After 10 cycles of the damp–heat cyclic test, the optical properties of the coating showed almost no change, indicating excellent damp–heat resistance. Full article

(This article belongs to the Section Thin Films and Interfaces)

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