Materials

22 pages, 4107 KB

Open AccessArticle

Asymmetric Supercapacitor Based on Biomass-Derived Carbon Electrodes Functionalized with NdFeB

by Ahmad Reshad Delawary, Constantin Bubulinca, Natalia E. Kazantseva, Petr Saha, Quoc Bao Le, Ram K. Gupta and Rudolf Kiefer

Materials 2026, 19(6), 1257; https://doi.org/10.3390/ma19061257 (registering DOI) - 22 Mar 2026

Abstract

Supercapacitors (SCs) are highly attractive energy storage devices, and modern research is focused on using waste materials to reduce environmental impact. This study processed biowaste from local brewery production to produce a highly specific mesoporous activated carbon (AC) for SC electrode scaffolds. Polyaniline [...] Read more.

Supercapacitors (SCs) are highly attractive energy storage devices, and modern research is focused on using waste materials to reduce environmental impact. This study processed biowaste from local brewery production to produce a highly specific mesoporous activated carbon (AC) for SC electrode scaffolds. Polyaniline (PANI) was synthesized and incorporated into the AC scaffold, thereby enhancing performance. The AC and PANI combination (ACP) achieved a specific capacitance of 173.7 F/g at 1 A/g, with 92% retention after 5000 cycles. Using NdFeB (ACN) particles, the anode showed a specific capacitance of 127 F/g and over 99% retention. An asymmetrical ACN//ACP cell demonstrated promising performance with 70% efficiency. This study highlights the potential of using biowaste for high-performance SC electrodes and the effective synergy between AC and PANI. Full article

(This article belongs to the Special Issue Performance of Supercapacitors for Energy Technologies and Applications)

14 pages, 6694 KB

Open AccessArticle

Cracking Mechanism and Life-Cycle Performance Evaluation of Early-Age Concrete Based on Environment-Damage Coupling

by Min Yuan, Zhiqiang Xie, Jiazheng Li, Yun Dong and Sheng Qiang

Materials 2026, 19(6), 1256; https://doi.org/10.3390/ma19061256 (registering DOI) - 22 Mar 2026

Abstract

Concrete is accelerating its transition towards green and low-carbon development, but its performance throughout its entire life cycle is significantly influenced by environmental changes, which remains a key technical challenge currently faced. The effects of early-age concrete tensile damage on thermal conductivity and [...] Read more.

Concrete is accelerating its transition towards green and low-carbon development, but its performance throughout its entire life cycle is significantly influenced by environmental changes, which remains a key technical challenge currently faced. The effects of early-age concrete tensile damage on thermal conductivity and moisture transport properties, as well as their coupling mechanism, remain unclear, leading to severe cracking. To explore the cracking mechanism of early-age concrete under the coupled conditions of environment and damage and to evaluate its performance throughout its lifecycle, this article conducts comparative experiments on the performance of concrete under high temperature, varying humidity, and damage conditions in the early age stage. The variation law of temperature, humidity, and strain of concrete is studied, and the evolution of microstructure and composition of concrete is explored. The response of porosity to ambient humidity exhibits opposite trends between restrained and unrestrained specimens, with rates of change of +0.0353%/RH and −0.0245%/RH, respectively. Furthermore, the study identified a critical turning point in ambient relative humidity (50% RH), which significantly alters the degree of hydration (Ca/Si ratio) of the concrete. The research results may provide theoretical and technical support for cracking risk assessment and crack control throughout the entire life cycle of concrete thin-walled structures. Full article

(This article belongs to the Special Issue Next-Generation Sustainable Materials for Green Manufacturing and Circular Economy)

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20 pages, 12398 KB

Open AccessArticle

Comparison of Surface Morphology and Topography of Additively Manufactured SS 316L Steel After AWJM in Dependence on Layer Orientation

by Radoslav Vandžura, Matúš Geľatko, Marek Čornanič, Vladimír Simkulet and František Botko

Materials 2026, 19(6), 1255; https://doi.org/10.3390/ma19061255 (registering DOI) - 22 Mar 2026

Abstract

Additively manufactured stainless steels are gaining considerable attention in the production of complex components, especially in the aerospace, food production, energy, and biomedical industries. Machining and achieving the desired surface properties of such materials remains a challenge. Abrasive waterjet machining technology appears to [...] Read more.

Additively manufactured stainless steels are gaining considerable attention in the production of complex components, especially in the aerospace, food production, energy, and biomedical industries. Machining and achieving the desired surface properties of such materials remains a challenge. Abrasive waterjet machining technology appears to be one of the options due to the advantages it brings. Removing support structures and separating individual parts is also one of the possible applications of this technology. This study investigates the effects of process parameters for individual cut qualities (Q1–Q5) of abrasive waterjet on the surface properties of additively manufactured stainless steel (SS 316L) specimens, considering the different mechanical properties of the material due to the direction of layering of the material during its production. Experimental specimens were prepared by selective laser melting technology with parameters ensuring the best possible quality of the resulting part. The results of the study showed changes in the topography of the machined surface, especially in the roughness parameters. Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy analysis proved the presence of fragmented abrasive particles in the cut areas. Full article

(This article belongs to the Special Issue Advanced Abrasive Processing Technology and Applications (Second Edition))

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21 pages, 1787 KB

Open AccessReview

Integrating Multifunctional Hydrogen-Bonded Organic Frameworks into Intelligent Packaging: Mechanisms, Design and Challenges

by Yabo Fu, Yubing Zhang, Congyao Wang, Jingmei Guan, Jiazi Shi, Hui Liu and Bo Lu

Materials 2026, 19(6), 1254; https://doi.org/10.3390/ma19061254 (registering DOI) - 22 Mar 2026

Abstract

The transition from passive containment to active, responsive management is defining the next generation of intelligent packaging. This evolution creates a critical demand for materials that can be precisely engineered to monitor, regulate, and protect. Hydrogen-bonded organic frameworks (HOFs) have emerged as a [...] Read more.

The transition from passive containment to active, responsive management is defining the next generation of intelligent packaging. This evolution creates a critical demand for materials that can be precisely engineered to monitor, regulate, and protect. Hydrogen-bonded organic frameworks (HOFs) have emerged as a uniquely versatile platform in this regard, owing to their synthetically tunable porosity, inherent biocompatibility, and exceptional solution processability derived from reversible supramolecular assembly. This review moves beyond cataloging applications to dissect the fundamental mechanisms by which HOFs enable smart packaging functions, including the following: (i) selective gas capture and atmosphere tailoring via molecular recognition within designed pores; (ii) high-sensitivity optical and electrochemical sensing for real-time quality and safety signaling; and (iii) stimuli-responsive release of active agents (e.g., antimicrobials). We further explore the frontier of integrating HOFs as functional fillers or coatings within polymeric matrices, a key step toward practical devices. Despite challenges such as structural stability and maintaining permanent porosity due to relatively weak hydrogen bonds, this work aims to provide a design blueprint for advancing HOFs from laboratory curiosities to core components of sustainable, multifunctional packaging systems. Full article

(This article belongs to the Section Green Materials)

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11 pages, 620 KB

Open AccessArticle

Analysis of High-Field-Induced Processes with Enthalpy Release in Martensite–Austenite MnCo(Fe)(GeSi) Alloys: Solving PPMS Artifact and Recovery of Heat Capacity

by Antonio Vidal-Crespo, F. Javier Romero, Jhon J. Ipus and Javier S. Blázquez

Materials 2026, 19(6), 1253; https://doi.org/10.3390/ma19061253 (registering DOI) - 22 Mar 2026

Abstract

The relaxation calorimeter option in the commercial Physical Property Measurement System (PPMS) has become widely used. Since its introduction, the capabilities of this technique for specific heat measurements have been critically discussed, particularly to avoid misinterpretation of data near phase transitions. Traditional methods [...] Read more.

The relaxation calorimeter option in the commercial Physical Property Measurement System (PPMS) has become widely used. Since its introduction, the capabilities of this technique for specific heat measurements have been critically discussed, particularly to avoid misinterpretation of data near phase transitions. Traditional methods rely on cooling curves after sample excitation, where sharp latent heat contributions during heating lead to clear deviations from the fitting model. However, subtle but extended enthalpy contributions (e.g., strain release) may mask these effects, allowing both heating and cooling curves to be well fitted using the standard PPMS protocol. In this work, we develop a procedure that assumes a constant extra power supplied due to subtle enthalpy contributions, enabling consistent interpretation of both heating and cooling curves. This procedure allows: (1) correction of specific heat measurements; and (2) quantification of the enthalpy involved in the transition. The procedure is applied to a magnetic-field-induced transformation in MnCo(Fe)Ge(Si) alloys. Two samples were studied: a single-phase austenite without any field-induced transition, used as a reference, and a mixed austenite-martensite sample, in which apparent deviations in the conductance of the wires evidence the presence of the anomaly. Full article

(This article belongs to the Section Metals and Alloys)

16 pages, 1782 KB

Open AccessArticle

Charge Transport and Thermoelectric Properties of Bornite with Fe-Site Off-Stoichiometry

by Hyemin Oh, Seungmin Lee, Hyeon-Sik O and Il-Ho Kim

Materials 2026, 19(6), 1252; https://doi.org/10.3390/ma19061252 (registering DOI) - 22 Mar 2026

Abstract

The effects of Fe non-stoichiometry on crystal structure, microstructural evolution, and thermoelectric transport properties were systematically investigated in bornite (Cu₅Fe_1+yS₄; −0.06 ≤ y ≤ 0.06) synthesized by mechanical alloying followed by hot pressing. X-ray diffraction analysis confirmed [...] Read more.

The effects of Fe non-stoichiometry on crystal structure, microstructural evolution, and thermoelectric transport properties were systematically investigated in bornite (Cu₅Fe_1+yS₄; −0.06 ≤ y ≤ 0.06) synthesized by mechanical alloying followed by hot pressing. X-ray diffraction analysis confirmed the formation of a single-phase orthorhombic bornite structure over the entire composition range. Anisotropic lattice distortion was observed with increasing Fe non-stoichiometry, manifested as contraction along the a-axis and expansion along the b- and c-axes, with a non-linear dependence on composition. Crystallite sizes estimated from Lorentzian peak fitting increased from 64.1 nm for the stoichiometric composition to 70.6–76.3 nm for Fe-deficient samples and 73.2–90.9 nm for Fe-excess samples. Hall-effect measurements revealed p-type semiconducting behavior for the stoichiometric composition, degenerate p-type transport with increased hole concentration under Fe-deficient conditions, and a transition to n-type behavior with reduced carrier mobility under Fe-excess conditions. While Fe-deficient samples retained high electrical conductivity and positive Seebeck coefficients, Fe-excess samples exhibited negative Seebeck coefficients at low temperatures with sign reversal at elevated temperatures. As a consequence, the power factor of Fe-deficient samples was enhanced by approximately 20–30% relative to the stoichiometric composition. In addition, the total thermal conductivity remained below 0.8 W·m⁻¹·K⁻¹ for all samples, and Fe non-stoichiometry effectively suppressed lattice thermal conductivity. Consequently, the Cu₅Fe_0.94S₄ composition achieved a maximum dimensionless figure of merit of ZT = 0.61 at 673 K, representing a performance enhancement of approximately 30–70% compared with the stoichiometric composition (ZT = 0.36 at 673 K and 0.47 at 723 K). Full article

(This article belongs to the Special Issue Advanced Thermoelectric Materials and Micro/Nanoscale Heat Transfer)

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18 pages, 8085 KB

Open AccessArticle

Investigation of Microstructural Characterization and Tensile Deformation Mechanisms in Inconel 617 Welded Joints Produced by GTAW

by Mingyang Zhao, Lang Wang, Wenhao Ren, Yuxin Wang, Tao Zhang and Zhengzong Chen

Materials 2026, 19(6), 1251; https://doi.org/10.3390/ma19061251 (registering DOI) - 21 Mar 2026

Abstract

The microstructural evolution and tensile behavior of Inconel 617 welded joints produced by gas tungsten arc welding (GTAW) with ERNiCrCoMo-1 filler were systematically investigated. Detailed microstructural characterization revealed that Cr-rich M₂₃C₆ and Ti-rich MC carbides are the dominant precipitates, while [...] Read more.

The microstructural evolution and tensile behavior of Inconel 617 welded joints produced by gas tungsten arc welding (GTAW) with ERNiCrCoMo-1 filler were systematically investigated. Detailed microstructural characterization revealed that Cr-rich M₂₃C₆ and Ti-rich MC carbides are the dominant precipitates, while Mo-rich M₆C forms locally along grain boundaries after thermal exposure. The fusion and weld zones exhibit fine dendritic morphologies with uniformly distributed precipitates, resulting in significant strengthening through precipitation and dislocation–pinning mechanisms. Owing to the low heat input and compositional compatibility between the weld and base metals, the heat-affected zone remains extremely narrow and free of compositional transitions. The welded joint attains tensile strengths of 920 MPa at room temperature and 605.5 MPa at 750 °C, corresponding to joint efficiencies of 117% and 121%, respectively, with fracture consistently occurring in the base metal. Deformation analysis shows that plasticity at room temperature is governed by planar slip and dislocation entanglement, whereas deformation twinning predominates at elevated temperatures owing to the reduced stacking-fault energy and the pinning effect of M₂₃C₆ carbides. These results provide key insights into the deformation and strengthening mechanisms controlling the high-temperature performance of GTAW-welded Inconel 617 joints and offer guidance for their application in advanced nuclear and high-temperature energy systems. Full article

(This article belongs to the Section Metals and Alloys)

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22 pages, 1702 KB

Open AccessArticle

Evaluation of Solid and Hollow Sand Brick Properties with Partial Replacement of Fine Aggregates by Ground Granulated Blast Furnace Slag

by Kamal Hosen and Alina Bărbulescu

Materials 2026, 19(6), 1250; https://doi.org/10.3390/ma19061250 (registering DOI) - 21 Mar 2026

Abstract

Ground granulated blast furnace slag (GGBFS), an industrial by-product of steel manufacturing, can be utilized as a partial replacement for natural fine aggregate in clay brick production. Although widely used in cementitious systems, its incorporation into sand bricks and its effects on key [...] Read more.

Ground granulated blast furnace slag (GGBFS), an industrial by-product of steel manufacturing, can be utilized as a partial replacement for natural fine aggregate in clay brick production. Although widely used in cementitious systems, its incorporation into sand bricks and its effects on key performance parameters remain insufficiently investigated. To fill in the gap, sand bricks containing 0–35% GGBFS (at 5% intervals) were tested for compressive strength, water absorption, thermal conductivity, and efflorescence. Optimal performance was achieved at 25% replacement. Compressive strength increased from 17.5 MPa (control) to 24 MPa (28.5% improvement). Water absorption decreased from 11.67% to 8.20% (29.7% reduction), and thermal conductivity decreased from 1.08 to 0.85 W/m·°C. No efflorescence was observed at 25% GGBFS, whereas higher replacement levels (30% and 35%) exhibited increased efflorescence. The results confirm that 25% GGBFS replacement enhances mechanical and durability-related properties of clay bricks, demonstrating its technical feasibility as an alternative fine aggregate. Full article

(This article belongs to the Special Issue Recovered or Recycled Materials for Composites and Other Materials)

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15 pages, 8850 KB

Open AccessArticle

Enhancing Self-Healing Performance of Cement-Based Materials Through Sodium Silicate and SAP Composite Incorporation

by Yumei Kang, Rongbao Wu, Yu Qiao and Chang Xu

Materials 2026, 19(6), 1249; https://doi.org/10.3390/ma19061249 (registering DOI) - 21 Mar 2026

Abstract

Conventional admixture-based self-healing technologies are often limited by inadequate internal water supply and a scarcity of unhydrated gel particles. Therefore, this study proposes a new self-healing method that leverages the synergistic interplay between the chemical repair of sodium silicate and the physical clogging [...] Read more.

Conventional admixture-based self-healing technologies are often limited by inadequate internal water supply and a scarcity of unhydrated gel particles. Therefore, this study proposes a new self-healing method that leverages the synergistic interplay between the chemical repair of sodium silicate and the physical clogging of superabsorbent polymers (SAPs) to overcome the aforementioned limitations. The healing efficiency of cement mortar was assessed through compressive strength recovery, capillary water absorption, and ultrasonic pulse velocity (UPV). Microstructural evolution and healing mechanisms were elucidated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results indicate that at an optimal dosage (0.5 wt.% for both admixtures), the healing performance is significantly enhanced: the compressive strength recovery rate reaches 103.1%, the capillary water absorption coefficient decreases by 16.57 × 10⁻³, and the UPV recovery achieves 95.4%. Microstructural analysis reveals that sodium silicate facilitates the reaction between

{Ca}^{2 +}

and

{S i O}_{3}^{2 -}

ions, leading to the in situ precipitation of dense C-S-H gel at the crack interface, thereby enabling chemical repair. In contrast, SAP contributes to physical sealing via a swelling and release mechanism. Full article

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

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20 pages, 3090 KB

Open AccessArticle

Hybrid Steel Fiber Design in Ultra-High-Performance Concrete Containing Coarse Aggregate Using Pore Size Distribution Within Coarse Aggregate Skeleton

by Rui Tang, Yinfei Du, Jian Zhang and Lingxiang Kong

Materials 2026, 19(6), 1248; https://doi.org/10.3390/ma19061248 (registering DOI) - 21 Mar 2026

Abstract

To address the challenge of coarse aggregates hindering steel fiber dispersion and reducing toughening efficiency in ultra-high-performance concrete containing coarse aggregate (UHPC-CA), this study proposes a hybrid fiber design method based on reverse adaptation to the aggregate structure: a paradigm where fiber proportions [...] Read more.

To address the challenge of coarse aggregates hindering steel fiber dispersion and reducing toughening efficiency in ultra-high-performance concrete containing coarse aggregate (UHPC-CA), this study proposes a hybrid fiber design method based on reverse adaptation to the aggregate structure: a paradigm where fiber proportions are inversely designed to match the quantified void size distribution within the coarse aggregate skeleton. Industrial X-ray computed tomography (X-CT) was employed to capture the internal structure of UHPC-CA. Digital image processing techniques were used to quantitatively characterize the size distribution within the coarse aggregate skeleton gap. Based on this distribution, the blending proportions of multi-scale (3–16 mm) copper-plated steel fibers were systematically determined. Three fiber configurations were compared: mono-sized 13 mm fibers (Type A), an empirical model based on aggregate size (Type B), and a quantitatively designed blend based on skeleton gap distribution (Type C). At the same fiber volume fraction, the mechanical property test results show that the C type achieves approximately 18.6% higher flexural strength and 29.1% higher splitting tensile strength compared to the A type, while showing 5.3% and 6.7% improvements over the B type, and the compressive strength also increased slightly (about 3.0%). The microanalysis further confirms that the fiber distribution in the C-type design was more uniform, and the bridging effect and crack resistance were more sufficient. The proposed gap-adaptive fiber design paradigm offers an effective approach for optimizing reinforcement distribution in composites, providing theoretical and practical value for high-performance UHPC-CA applications. Full article

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

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12 pages, 2203 KB

Open AccessCommunication

Theoretical Investigation of Stiffness and Vibration Frequency Enhancement in Novel Membrane-Wrapped Lattice Beams

by Peiyao Xi, Hao Zhou, Canghai Tan, Chuang Shi, Rongqiang Liu and Jianzhong Yang

Materials 2026, 19(6), 1247; https://doi.org/10.3390/ma19061247 (registering DOI) - 21 Mar 2026

Abstract

Bending-dominated lattice structures offer superior stability but suffer from low stiffness and natural frequencies, posing resonance risks in aerospace applications. To address this, a novel Membrane-Wrapped Lattice (MWL) encapsulated by a micrometer-scale metallic film is proposed. A theoretical framework based on the tension-compression [...] Read more.

Bending-dominated lattice structures offer superior stability but suffer from low stiffness and natural frequencies, posing resonance risks in aerospace applications. To address this, a novel Membrane-Wrapped Lattice (MWL) encapsulated by a micrometer-scale metallic film is proposed. A theoretical framework based on the tension-compression asymmetry of the membrane is established to analyze the influence of membrane thickness on the neutral axis shift, ultimately deriving analytical formulations for flexural stiffness and natural frequencies. MWL specimens with varying membrane thicknesses (0–50 μm) were fabricated via selective laser melting and adhesive bonding, then subjected to three-point bending and vibration tests. Results demonstrate that wrapping with a 50 μm 316 L stainless steel membrane increases the flexural stiffness by 128% and the fundamental natural frequency by 85%. The experimental measurements align well with theoretical and numerical predictions, validating this lightweight, high-stiffness design strategy. Full article

(This article belongs to the Section Porous Materials)

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23 pages, 2910 KB

Open AccessArticle

Transient Contact Elastic–Plastic Characteristics Analysis of Rail Welded Joints in Heavy-Haul Railways

by Chen Liu and Zhiqiang Wang

Materials 2026, 19(6), 1246; https://doi.org/10.3390/ma19061246 (registering DOI) - 21 Mar 2026

Abstract

This study investigates the transient wheel–rail contact mechanics of welded joints in heavy-haul rails via a validated 3D finite element model, and analyzes the stick-slip behavior, dynamic response and elastoplastic characteristics in the base material zone, heat-affected zone and weld bead zone. Results [...] Read more.

This study investigates the transient wheel–rail contact mechanics of welded joints in heavy-haul rails via a validated 3D finite element model, and analyzes the stick-slip behavior, dynamic response and elastoplastic characteristics in the base material zone, heat-affected zone and weld bead zone. Results show a distinct contact state transition from stick-slip in the base material to predominant slip within the welded zones, indicating higher wear susceptibility. Dynamic response analysis reveals the highest and lowest contact-point acceleration amplitudes in the base material and heat-affected zone, respectively, due to material heterogeneity. Plastic deformation consistently initiates at the rail surface, where stress and strain concentrate, establishing it as the primary site for damage nucleation. A systematic parametric study shows that plastic deformation can be effectively mitigated by increasing the yield strength and elastic modulus of the welded joint material, or reducing the wheelset velocity, unsprung mass and wheel–rail friction coefficient. In contrast, adjusting the primary suspension and fastener parameters exerts a negligible influence on plastic deformation control. These findings provide a mechanistic basis for optimizing the performance and maintenance of welded joints in heavy-haul rail operations. This study reveals the coupling law of multiple mechanisms among contact behavior, dynamic response and material failure during the damage initiation process of rail welded joints from the mechanistic perspective, which provides a theoretical basis for the structural optimization, condition assessment and maintenance of rail welded joints in heavy-haul railways. Full article

(This article belongs to the Special Issue Road and Rail Construction Materials: Development and Prospects)

20 pages, 8361 KB

Open AccessArticle

Synergistic Effects of Pre-Stretching and Aging Temperature on Precipitation Behavior and Damage Tolerance of an Al-Cu-Li Alloy

by Ben Lin, Changlin Li, Xiwu Li, Yongan Zhang, Kai Wen, Ying Li, Lizhen Yan, Yanan Li, Hongwei Yan, Zhihui Li and Baiqing Xiong

Materials 2026, 19(6), 1245; https://doi.org/10.3390/ma19061245 (registering DOI) - 21 Mar 2026

Abstract

This study systematically investigates the synergistic effects of the pre-stretching deformation and aging temperature on the precipitation behavior and mechanical properties of an Al-Cu-Li alloy. The results indicate that increasing the pre-stretching deformation significantly refines and increases the number density of T₁ [...] Read more.

This study systematically investigates the synergistic effects of the pre-stretching deformation and aging temperature on the precipitation behavior and mechanical properties of an Al-Cu-Li alloy. The results indicate that increasing the pre-stretching deformation significantly refines and increases the number density of T₁ and θ′ phases while optimizing the grain boundary precipitate morphology, thereby enhancing the fracture toughness and fatigue resistance without compromising the high strength. In contrast, elevating the aging temperature promotes the coarsening of the T₁ phase, inhibits θ′ precipitation, and coarsens the grain boundary precipitates, leading to a deteriorated damage tolerance. By matching 3.5~4.5% pre-stretching with 145~155 °C aging, a synergistic optimization of ultra-high strength and damage tolerance can be achieved. Full article

(This article belongs to the Special Issue Physical Metallurgy of Metals and Alloys (4th Edition))

15 pages, 2734 KB

Open AccessArticle

PDMS–Epoxy Micro-Nano Composite Structures Constructed via Open-Loop Addition Reactions and Their Optical and Antifouling Performance Modulation

by Chao Xu, Xiaofan Chen, Shimin Zhai, Dan Wang and Ruofei Zhu

Materials 2026, 19(6), 1244; https://doi.org/10.3390/ma19061244 (registering DOI) - 21 Mar 2026

Abstract

Epoxy resin (E-51) exhibits excellent adhesion and is widely used in the preparation of functional composite coatings. However, its smooth surface lacking micro/nano composite structures limits its self-cleaning capability and optical properties. Direct incorporation of organic silicone or inorganic fillers often faces severe [...] Read more.

Epoxy resin (E-51) exhibits excellent adhesion and is widely used in the preparation of functional composite coatings. However, its smooth surface lacking micro/nano composite structures limits its self-cleaning capability and optical properties. Direct incorporation of organic silicone or inorganic fillers often faces severe phase separation and filler agglomeration issues, resulting in defects in coating durability and weather resistance. To address these challenges, this study developed a synergistic modification strategy integrating surface energy modulation with the architectural design of micro/nano-structures. Amino-terminated PDMS undergoes ring-opening addition reactions with epoxy groups in the epoxy resin, while functionalized barium sulfate nanoparticles modified with dual silane coupling agents are incorporated to enhance optical properties. This synergistic approach not only resolved interfacial compatibility but also endowed the PDMS@EP-BaSO₄ coating with outstanding comprehensive properties; the water contact angle increased to 123.5°, demonstrating an easy-to-clean benefit. Visible light reflectance reached 95%, and emissivity rose to 90%. Furthermore, when applied to metal surfaces, the coating exhibited excellent stability against acid–alkali–salt corrosion, extreme temperatures, and ultrasonic agitation. This work provided a novel approach for developing protective coatings that integrated high reflectance, high emissivity, and long-term anti-soiling properties. Full article

(This article belongs to the Topic Advanced Composite Materials)

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17 pages, 7464 KB

Open AccessArticle

Magnetoelectric Coupling in Ba_0.85Ca_0.15Ti_0.92Zr_0.08O₃ with Ultra-Low Concentrations of CoFe₂O₄

by Alejandro Campos-Rodríguez, Brayan Carmona-Conejo, Miguel H. Bocanegra-Bernal, Gabriel Rojas-George and Armando Reyes-Rojas

Materials 2026, 19(6), 1243; https://doi.org/10.3390/ma19061243 (registering DOI) - 21 Mar 2026

Abstract

Magnetoelectric (ME) materials that exhibit simultaneous coupling between electric polarization and magnetization have attracted significant attention due to their potential technological applications in the emerging generation of multifunctional devices. In this research, Ba_0.85Ca_0.15Ti_0.92Zr_0.08O₃-CoFe [...] Read more.

Magnetoelectric (ME) materials that exhibit simultaneous coupling between electric polarization and magnetization have attracted significant attention due to their potential technological applications in the emerging generation of multifunctional devices. In this research, Ba_0.85Ca_0.15Ti_0.92Zr_0.08O₃-CoFe₂O₄:x (x = 0.1, 0.2, 0.3% mol) composites were synthesized using solid-state and sol–gel combustion chemical methods to elucidate their ME coupling at ultra-low concentrations of the magnetic phase. Rietveld refinement and Raman spectroscopy results confirm a shift in the morphotropic phase boundary (MPB), evidenced by an increase in the tetragonal phase relative to the orthorhombic structure. High stability of the P4mm and Amm2 symmetries is reached at 1300 °C without diffusion of Fe and Co into the octahedral site. At this temperature, the CoFe₂O₄ spinel structure remains stable without secondary phases. The orthorhombic phase fraction decreases from 55% to 37% as the magnetic phase fraction increases, driven by stress and constraint rather than ionic interactions alone. The Curie temperature decreases from 99 to 90 °C, attributed to the grain-size reduction effect rather than structural disorder. The dielectric permittivity (ε_r) reaches an absolute value of 5070 and progressively decreases with increasing magnetic saturation. An increase in compressive residual stress is observed, which ensures the mechanical stability of the electroceramics. Magnetoelectric (ME) coupling, evaluated through measurements of electric polarization as a function of the magnetic field, shows an increase from 3.8 to 4.9 μC/cm² under a magnetic field of 50 Oe. The composites with x = 0.2 and 0.3 mol% exhibit potential for applications in fast-switching magnetoelectric devices and magnetic field sensors. Full article

(This article belongs to the Section Advanced and Functional Ceramics and Glasses)

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18 pages, 6155 KB

Open AccessArticle

Mechanical Properties and Freeze–Thaw Cycling Degradation of Loess Improved with an Ionic Curing Agent and Cement Composite

by Xingwei Wang, Jiandong Li, Xu Wang, Baiwei Li, Yanjie Zhang and Zhen Zuo

Materials 2026, 19(6), 1242; https://doi.org/10.3390/ma19061242 (registering DOI) - 21 Mar 2026

Abstract

To address the engineering problems of high cement content, high brittleness, and weak frost resistance of cement-improved loess in the seasonal frozen soil area of Northwest China, F1 ion curing agent (F1) and cement composite improved loess (FCIL) were used in this paper. [...] Read more.

To address the engineering problems of high cement content, high brittleness, and weak frost resistance of cement-improved loess in the seasonal frozen soil area of Northwest China, F1 ion curing agent (F1) and cement composite improved loess (FCIL) were used in this paper. Through unconfined compressive (UC) strength tests, consolidated undrained (CU) triaxial shear tests, and microscopic pore characteristics analysis, the mechanical properties, freeze–thaw cycle deterioration law, and microscopic pore structure of FCIL were studied. The effects of cement content (C_c), F1 dosage (C_F), number of freeze–thaw cycles (N_F-T), and confining pressure (σ₃) on the strength, deformation behavior, and pore characteristics of FCIL were analyzed. The synergistic improvement mechanism of FCIL, as well as the freeze–thaw damage mechanism, was elucidated. The results show that C_c is the primary factor controlling the strength of improved loess. The incorporation of F1 can further increase UCS and markedly enhance the failure strain (ε_f), thereby achieving simultaneous improvements in strength and ductility. An appropriate mix proportion was identified as C_F = 0.2 L/m³ and C_c = 6%. After 7 d curing, FCIL exhibited a UCS of 1.35 MPa, a cohesion (c) of 205 kPa, an internal friction angle (φ) of 36.2°, and ε_f 1.8 times that of loess improved with C_c = 6% cement alone. CU triaxial shear tests indicate that, under all tested conditions, the stress–strain responses of FCIL exhibit σ3-sensitive strain-softening behavior. As C_c and σ₃ increase, triaxial peak strength (q_max) and secant modulus (E₅₀) increase significantly. Compared with natural loess (NL), FCIL shows a markedly lower porosity (n), a substantial increase in the proportion of micropores, and reductions in medium and small pores. After multiple freeze–thaw cycles, the evolution of the pore structure is effectively restrained. This indicates that the combined use of F1 and cement promotes the formation of a dense layered stacking structure, significantly improves the microscopic pore-size distribution, and enhances the mechanical performance of loess under freeze–thaw environments. Full article

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13 pages, 1211 KB

Open AccessArticle

Effects of Nitrogen Ion Implantation on Wettability and Surface Roughness of WC–Co Tools Used for Wood-Based Panel Machining

by Marek Barlak, Jacek Wilkowski, Radosław Auriga, Jerzy Zagórski, Piotr Boruszewski and Piotr Borysiuk

Materials 2026, 19(6), 1241; https://doi.org/10.3390/ma19061241 (registering DOI) - 21 Mar 2026

Abstract

This work explores the effect of nitrogen ion implantation on the wettability of the cemented tungsten carbide–cobalt (WC–Co) tool surface used for wood-based panel machining. Nitrogen ions with an energy of 50 keV and a fluence of 1 × 10¹⁷ and 5 [...] Read more.

This work explores the effect of nitrogen ion implantation on the wettability of the cemented tungsten carbide–cobalt (WC–Co) tool surface used for wood-based panel machining. Nitrogen ions with an energy of 50 keV and a fluence of 1 × 10¹⁷ and 5 × 10¹⁷ cm⁻² were implanted into the surface layer of commercially available WC–Co indexable knives using the implanter without a mass-separated ion beam. The wettability was characterized by a contact angle instrument. The implantation of nitrogen ions into WC–Co tools caused a statistically significant and practically useful decrease in the contact angle. This obtained effect was dependent on the fluence of the implanted ions, and it changed over time. This effect may also explain the transfer from the workpiece and the surface capture of carbon atoms in the secondary structure formed during the machining of wood materials on tools with ion implantation. On the other hand, the layer of carbon on the surface of the tool formed during machining explains the reduction in friction coefficient observed in experiments and the increase in tool life during cutting. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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15 pages, 3713 KB

Open AccessArticle

Constructing Li-O-Vacancy Configuration Coupling with a Layered/Spinel Mixed Structure in Li-Deficient Li-Rich Layered Oxides to Realize Stable Oxygen Redox

by Yibin Zhang, Meng Wang, Bao Qiu and Zhaoping Liu

Materials 2026, 19(6), 1240; https://doi.org/10.3390/ma19061240 (registering DOI) - 21 Mar 2026

Abstract

Owing to the synergistic effect of cationic and anionic charge compensation, Li-rich layered oxide cathodes stand as the most promising candidates for next-generation high-energy-density Li-ion batteries. However, the unstable oxygen redox process triggers irreversible oxygen release and structural degradation of the layered framework, [...] Read more.

Owing to the synergistic effect of cationic and anionic charge compensation, Li-rich layered oxide cathodes stand as the most promising candidates for next-generation high-energy-density Li-ion batteries. However, the unstable oxygen redox process triggers irreversible oxygen release and structural degradation of the layered framework, which further destabilizes the Li-O-Li configuration and leads to severe performance decay. In this work, a layered/spinel heterostructure coupled with a stabilized Li-O-vacancy configuration is successfully constructed in a Li-rich layered oxide cathode. This design enables outstanding structural and electrochemical stability, delivering an initial discharge capacity of 232 mAh g⁻¹ with a Coulombic efficiency of 90.5%. Moreover, the cathode retains 86.5% of its capacity after 100 cycles. The proposed structural design strategy offers a new pathway toward high-performance Li-rich layered oxide cathodes. Full article

(This article belongs to the Section Energy Materials)

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14 pages, 1170 KB

Open AccessArticle

Finite Element Analysis of Peri-Implant Stress in Maxillary All-on-Four Rehabilitation: Effects of Posterior Implant Angulation and Loading Protocol

by Juan Alberto Aristizábal-Hoyos, Leidy Katherine Gil-Tabares, Natalia Giraldo-Vélez, Martha Isabel Torres-Arteaga, Catalina Garces-Gonzalez, Olga Patricia López-Soto, Héctor Fuentes-Barría, Raúl Aguilera-Eguía and Lisse Angarita-Davila

Materials 2026, 19(6), 1239; https://doi.org/10.3390/ma19061239 (registering DOI) - 20 Mar 2026

Abstract

Objective: To evaluate the biomechanical effects of varying posterior implant inclinations and loading protocols on peri-implant stress distribution in full-arch maxillary rehabilitations using the All-on-Four concept. Methodology: A three-dimensional finite element model of an edentulous atrophic maxilla was developed from a digital point [...] Read more.

Objective: To evaluate the biomechanical effects of varying posterior implant inclinations and loading protocols on peri-implant stress distribution in full-arch maxillary rehabilitations using the All-on-Four concept. Methodology: A three-dimensional finite element model of an edentulous atrophic maxilla was developed from a digital point cloud. Four implants were placed according to the All-on-Four protocol: two anterior vertical implants and two posterior implants with inclinations of 0°, 15°, 30°, or 45°. Mini-abutments and a titanium bar prosthesis were included. Material properties were assumed as homogeneous, isotropic, and linearly elastic. Immediate loading was simulated using frictional contacts (µ = 0.3), whereas delayed loading assumed complete osseointegration (bonded contacts). The models were meshed using 10-node quadratic tetrahedral elements (SOLID187) in ANSYS^®. Maximum von Mises stress in cortical bone, cancellous bone, implants, abutments, and the prosthetic bar was assessed. Results: Posterior implant tilt significantly reduced peri-implant stress. Under immediate loading, the highest stress occurred at 0° inclination in the posterior left implant (82.36 MPa) and decreased progressively with increasing tilt, reaching 33.63 MPa at 45° (≈59% reduction). Delayed loading generally produces lower stress magnitudes, particularly at extreme tilts. Anterior implants experienced lower stress levels across all configurations. Comparative analysis demonstrated that immediate loading increased stress at lower angulations, while differences between loading protocols were minimal at higher inclinations. Conclusions: Posterior implant angulation and loading protocol critically influence peri-implant stress distribution. Increased posterior tilt combined with appropriate loading reduces peak cortical bone stresses, supporting biomechanical optimization in All-on-Four maxillary rehabilitations. Full article

(This article belongs to the Special Issue Advances in Dental Implants: Materials, Procedures and Clinical Response)

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