Materials

17 pages, 2522 KB

Open AccessArticle

Reutilizing Flavonoids from Agricultural By-Products for In Situ Generation and Immobilization of AgNPs on Silk Towards Coloration, Antimicrobial and Anti-UV Functions

by Wei Chen, Yijie Yue, Xiaoqi Zhou, Jingyu Sun, Leyang Chen, Xiaoyan Hu and Yuyang Zhou

Materials 2025, 18(23), 5409; https://doi.org/10.3390/ma18235409 (registering DOI) - 30 Nov 2025

Abstract

The utilization of agro-byproducts for textile dyeing and finishing is strongly suggested to meet sustainability and cost-efficiency objectives. Despite recently proliferating studies, three major issues hinder the industrialization of such a technique: identifying reasonable bio-resources, ensuring compatibility between agro-byproducts and textile substrates, and [...] Read more.

The utilization of agro-byproducts for textile dyeing and finishing is strongly suggested to meet sustainability and cost-efficiency objectives. Despite recently proliferating studies, three major issues hinder the industrialization of such a technique: identifying reasonable bio-resources, ensuring compatibility between agro-byproducts and textile substrates, and achieving satisfactory color depth, functionality, and durability. This research introduces an approach that forms and fixes silver nanoparticles (AgNPs) on silk using three representative flavonoids (FLs)—Quercetin (QUE), Baicalin (BAI), and Rutin (RUT)—through a single-step in situ bio-reduction. Results demonstrate that FLs-synthesized AgNPs@silk generates attractive spectra of hues, varying from pale cream-brown to deep golden-brown. Using an equivalent quantity of FLs, the color intensity of silk descends in QUE-Ag@silk > BAI-Ag@silk > RUR-Ag@silk, due to the decreasing reactivity and binding affinity of FLs to silk. SEM reveals uniformly distributed spherical AgNPs in dimensions between 20 and 40 nm on silk and the dimension inversely correlates with FLs concentration while being directly proportional to silver nitrate. The modified silk exhibits remarkable antimicrobial performance (>98% pathogen elimination) and exceptional wash resistance (>90% reduction both of E. coli and S. aureus after ten cycles of washing). Additionally, the FLs-synthesized AgNPs provide silk with superior UV shielding capability. This study stems from environmental awareness and sustainable production of AgNPs by FLs, ready for developing hygienic and therapeutic textile materials. Full article

(This article belongs to the Special Issue Functional Textiles: Fabrication, Processing and Applications)

23 pages, 3087 KB

Open AccessArticle

The Influence of REE Steel Modification on the Microstructure and Mechanical Characteristics Using Fractographic Analyses

by Robert Pała and Piotr Furmańczyk

Materials 2025, 18(23), 5408; https://doi.org/10.3390/ma18235408 (registering DOI) - 30 Nov 2025

Abstract

Improving the operational parameters of machinery necessitates the use of materials with higher mechanical characteristics. Strength characteristics, particularly fracture toughness, are strongly linked to the material’s microstructure. This article presents the results of a study examining the effect of microstructure on the mechanical [...] Read more.

Improving the operational parameters of machinery necessitates the use of materials with higher mechanical characteristics. Strength characteristics, particularly fracture toughness, are strongly linked to the material’s microstructure. This article presents the results of a study examining the effect of microstructure on the mechanical properties and fracture toughness of G17CrMo5-5 cast steel in its basic and rare-earth modified variants. The addition of rare-earth elements (REEs) to the melt resulted in a reduction and homogenization in grain size, as well as a reduction in the size and shape of non-metallic inclusions. For modified cast steel, there were no grains with a chord size above 120 μm and inclusions with a diameter above 5.5 μm. Changes in the microstructure of modified cast steel resulted in a slight increase in strength properties. It significantly increased the fracture toughness: for unmodified cast steel at a temperature of −20 °C, the fracture toughness increased from 94 kN/m to 416 kN/m for modified cast steel. Fracture fractographic analysis using non-contact microroughness measurement techniques or measuring the width of the stretch zone allowed for the calculation of fracture toughness without the need for a conventional test. Fracture toughness calculated based on fractographic analysis can be determined for brittle fracture and brittle fracture preceded by plastic growth. Numerical simulations of the loading of specimens tested for fracture toughness allowed us to determine the effect of the REE steel modification on the stress field distribution ahead of the crack front. The modification resulted in a change in the opening stress distribution and the location of its maximum at each temperature. The use of REE modification is an effective approach for homogenizing the microstructure and increasing the fracture toughness of cast steel, especially when the material operates at temperatures in the interval of the fracture mechanism change. Full article

(This article belongs to the Section Metals and Alloys)

15 pages, 1115 KB

Open AccessArticle

Assessment of the Service Life of Polyethylene Pipes with Controlled Defects Using Internal Pressure Test

by Ioana-Daniela Manu, Marius Gabriel Petrescu, Cătălin Blag and Ramadan Ibrahim Naim

Materials 2025, 18(23), 5407; https://doi.org/10.3390/ma18235407 (registering DOI) - 30 Nov 2025

Abstract

Controlled geometry defects can be volumetric defects, usually located on the outer surface of the pipe, having different orientations and lengths and identical depths. This type of defect corresponds to the type obtained using a damage mechanism, as presented by API 579-1/ASME FFS-1, [...] Read more.

Controlled geometry defects can be volumetric defects, usually located on the outer surface of the pipe, having different orientations and lengths and identical depths. This type of defect corresponds to the type obtained using a damage mechanism, as presented by API 579-1/ASME FFS-1, Part 9, called crack-type defects. The research presented in this paper was intended to evaluate the influence of controlled defects on the strength of an HDPE water pipe, PE100 (Ø 90 × 5.4), SDR 17, PN 10 bar, subjected to internal pressure. The methods applied were the internal pressure test and numerical simulation. The article’s main findings were the critical pressure P_cr, the critical time t_cr, the critical depth of defect a_cr, and the remaining service life t. The remaining service life was approximately 83 years for the pipe with a defect oriented circumferentially, and 69 years for the pipe with a defect oriented longitudinally. Full article

29 pages, 448 KB

Open AccessReview

A Comprehensive Review of θ-Series Precipitates in Aluminum Alloys

by Bin Chen

Materials 2025, 18(23), 5406; https://doi.org/10.3390/ma18235406 (registering DOI) - 30 Nov 2025

Abstract

This review systematically synthesizes the research progress on θ-series precipitates. It traces the historical evolution of θ-series precipitate research, from the accidental discovery of age hardening in Duralumin to the atomic-scale insights enabled by advanced electron microscopy and computational methods. The precipitation sequence [...] Read more.

This review systematically synthesizes the research progress on θ-series precipitates. It traces the historical evolution of θ-series precipitate research, from the accidental discovery of age hardening in Duralumin to the atomic-scale insights enabled by advanced electron microscopy and computational methods. The precipitation sequence (supersaturated solid solution → GP zones → θ″ → θ′ → θ), transformation mechanisms, and interfacial characteristics of θ′/Al are comprehensively analyzed, with special attention to ongoing controversies such as the structure of GP zones and the pathways of θ″ → θ′ transition. Furthermore, the review discusses how alloying elements regulate θ′ stability through interfacial segregation, vacancy interactions, and co-precipitation effects. Critical unresolved challenges are highlighted, including the kinetic limitations of θ′ coarsening and the need for mechanistic studies on multi-element microalloying. This synthesis aims to provide a foundation for future research toward designing high-performance age-hardenable aluminum alloys. Full article

(This article belongs to the Special Issue Mechanical Performance and Microstructural Characterization of Light Alloys (3rd Edition))

15 pages, 5489 KB

Open AccessArticle

Steam Coating-Based Synthesis and Corrosion Inhibition Performance of Mg–Al-Layered Double Hydroxide Films with Different Interlayer Anions on Al-Si-Cu Alloys

by Io Matsui, Hikari Ouchi, Yuki Atsuumi, Kota Fukuhara and Takahiro Ishizaki

Materials 2025, 18(23), 5405; https://doi.org/10.3390/ma18235405 (registering DOI) - 30 Nov 2025

Abstract

Al–Si–Cu alloy is one of the aluminum die-cast alloys widely used in industry. Due to the presence of Si and Cu elements in the Al–Si–Cu alloy, the corrosion resistance of the Al–Si–Cu alloy is lowered. Thus, developing a corrosion-resistant film on the Al–Si–Cu [...] Read more.

Al–Si–Cu alloy is one of the aluminum die-cast alloys widely used in industry. Due to the presence of Si and Cu elements in the Al–Si–Cu alloy, the corrosion resistance of the Al–Si–Cu alloy is lowered. Thus, developing a corrosion-resistant film on the Al–Si–Cu alloy is necessary. A layered double hydroxide (LDH) film is recognized as a promising corrosion-resistant coating. LDHs exhibit a distinct structure where positively charged basic layers (metal hydroxides) are interleaved with intermediate layers that accommodate charge-compensating anions and hydration water. The positively charged layers allow for the exchange of anions as interlayers, enabling the incorporation of various anions into the interlayer. The difference in the anion species in the interlayer of the LDH films can affect corrosion-resistant performance. In this study, we aimed to prepare Mg–Al LDH films intercalated with different anions (NO₃⁻, MoO₄²⁻, VO₄³⁻, and PO₄³⁻) and investigate the corrosion resistance of the LDH films. The films were prepared on die-cast Al–Si–Cu alloys using steam coating and immersion processes. The prepared LDH films were characterized by XRD, SEM, FT-IR, and electrochemical measurements. The electrochemical measurements revealed that Mg–Al LDH films intercalated with MoO₄²⁻ showed the most superior corrosion resistance among all films prepared in this study. Full article

(This article belongs to the Section Corrosion)

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30 pages, 8136 KB

Open AccessArticle

AE-YOLO: Research and Application of the YOLOv11-Based Lightweight Improved Model in Photovoltaic Panel Surface Intelligent Defect Detection

by Bin Zheng and Yunjin Yang

Materials 2025, 18(23), 5404; https://doi.org/10.3390/ma18235404 (registering DOI) - 30 Nov 2025

Abstract

With the rapid development of renewable energy, surface defect detection of photovoltaic panels has become an important link in improving photoelectric conversion efficiency and ensuring safety. However, there are various types of surface defects on photovoltaic panels with complex backgrounds, and traditional detection [...] Read more.

With the rapid development of renewable energy, surface defect detection of photovoltaic panels has become an important link in improving photoelectric conversion efficiency and ensuring safety. However, there are various types of surface defects on photovoltaic panels with complex backgrounds, and traditional detection methods face challenges such as low efficiency and insufficient accuracy. This article proposes a lightweight improved model AE-YOLO (YOLOv11+Adown +ECA) based on YOLOv11, which improves detection performance and efficiency by introducing a lightweight dynamic down-sampling module (Adown) and an Efficient Channel Attention (ECA). The Adown module reduces the complexity of computational and parameters through steps such as average pooling preprocessing, channel dimension segmentation, branch feature processing, and feature fusion. The ECA mechanism enhances the model’s response to defect sensitive feature channels and improves its ability to discriminate low contrast small defects through adaptive average pooling, one-dimensional convolution, and sigmoid activation. The experimental results indicate that the AE-YOLO model performs well on the PVEL-AD dataset. mAP@0.5 reached 90.3%, the parameter count decreased by 18.7%, the computational load decreased by 19%, and the inference speed reached 259.56 FPS. The ablation experiment further validated the complementarity between Adown and ECA modules, providing an innovative solution for real-time and accurate defect detection of photovoltaic panels in industrial scenarios. Full article

(This article belongs to the Special Issue Intelligent Damage Detection of Materials and Structural Health Monitoring Technology)

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15 pages, 3082 KB

Open AccessArticle

Computational Design of High-Performance U-Shaped Seismic Dampers Using Statistical Optimization

by Ignacio Ríos, Álvaro Gómez, Felipe Romero, Alexis Salas, Angelo Oñate, Carlos Lanziotti, Sebastián Andrés Toro, Laurent Duchêne and Víctor Tuninetti

Materials 2025, 18(23), 5403; https://doi.org/10.3390/ma18235403 (registering DOI) - 30 Nov 2025

Abstract

Passive metallic dampers are critical for the seismic resilience of structures, yet their design has historically relied on incremental modifications rather than systematic optimization. This study introduces and validates a data-driven workflow that combines the Taguchi method with nonlinear finite element analysis to [...] Read more.

Passive metallic dampers are critical for the seismic resilience of structures, yet their design has historically relied on incremental modifications rather than systematic optimization. This study introduces and validates a data-driven workflow that combines the Taguchi method with nonlinear finite element analysis to design novel U-shaped seismic dampers (USSDs) with superior performance. Building on an experimentally validated computational model from prior work, an L25 orthogonal array was employed to systematically investigate key geometric parameters, with an Analysis of Variance (ANOVA) identifying height, thickness, and length as the most influential factors on damper behavior. This statistical insight guided the creation of two optimized models, with the UD-M4 model demonstrating a nearly seven-fold increase in total energy dissipation (340.6 kJ vs. 51.2 kJ), a nine-fold increase in stiffness, and a 50% improvement in deformability compared to the commercial UD-40 baseline. The primary contribution of this work is the validation of an efficient statistical–computational methodology for the performance-based design of next-generation seismic protection devices, moving beyond traditional trial-and-error approaches. Full article

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

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21 pages, 6318 KB

Open AccessArticle

Study on Antibacterial Powder Coatings Based on Halloysite/Biopolymer Compounds

by Katarzyna Krawczyk, Barbara Pilch-Pitera, Michał Kędzierski, Małgorzata Zubielewicz, Izabela Kunce, Ewa Langer, Sebastian Jurczyk, Grażyna Kamińska-Bach, Ewa Ciszkowicz, Marta Przybysz-Romatowska, Damian Wojda, Leszek Komorowski and Michael Hilt

Materials 2025, 18(23), 5402; https://doi.org/10.3390/ma18235402 (registering DOI) - 30 Nov 2025

Abstract

This study presents an eco-friendly approach to antibacterial polyester powder coatings by incorporating hybrid additives composed of biopolymers immobilized on halloysite nanotubes. Polylysine (PLY) and quaternized chitosan (CH-Q) were used as natural antimicrobial agents, while halloysite (HAL) acted as a carrier to improve [...] Read more.

This study presents an eco-friendly approach to antibacterial polyester powder coatings by incorporating hybrid additives composed of biopolymers immobilized on halloysite nanotubes. Polylysine (PLY) and quaternized chitosan (CH-Q) were used as natural antimicrobial agents, while halloysite (HAL) acted as a carrier to improve dispersion and reduce leaching. HAL/PLY and HAL/CH-Q hybrids were incorporated into polyester coatings and evaluated for morphology, mechanical properties, water resistance, and antibacterial performance (ISO 22196). The HAL/PLY coating demonstrated a strong bactericidal effect, reducing Escherichia coli and Staphylococcus aureus by 99.9989% and 99.9993%, respectively. HAL/CH-Q showed moderate activity against E. coli (50.2323%) but high activity against S. aureus (98.6500%). Immobilization of biopolymers on the halloysite surface improved dispersion and barrier properties while enabling a silver-free antibacterial effect. The results demonstrate a sustainable strategy for multifunctional powder coatings based on naturally derived antimicrobial components. Full article

(This article belongs to the Special Issue Recent Advances and Emerging Challenges in Functional Coatings (2nd Edition))

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18 pages, 3119 KB

Open AccessArticle

Physics-Informed Neural Networks for Thermo-Responsive Hydrogel Swelling: Integrating Constitutive Models with Sparse Experimental Data

by Seyed Amirmasoud Takmili, Eunsoo Choi, Alireza Ostadrahimi and Mostafa Baghani

Materials 2025, 18(23), 5401; https://doi.org/10.3390/ma18235401 (registering DOI) - 30 Nov 2025

Abstract

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels are temperature-sensitive materials whose swelling is difficult to predict near the gel collapse temperature (GCT). A physics-informed neural network (PINN) was developed in which a stabilized free-energy model is embedded and sparse data for free and uniaxially constrained swelling are [...] Read more.

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels are temperature-sensitive materials whose swelling is difficult to predict near the gel collapse temperature (GCT). A physics-informed neural network (PINN) was developed in which a stabilized free-energy model is embedded and sparse data for free and uniaxially constrained swelling are assimilated. Across datasets, the PINN reduces test RMSE by 44% at low crosslink density (

N ν = 0.0035

) and by 65% at higher density (

N ν = 0.02

), with coverage inside ±RMSE bands improving from 61.9% to 76.2% for free swelling at Nν = 0.0035. Under constraint, test relative error decreases from 19.95% to 11.86% (

n = 1

) and from 9.19% to 5.90% (

n = 3

), while preserving thermodynamic stability. The method sharpens the transition slope near the gel-collapse temperature and narrows prediction intervals without overfitting, capturing cold-regime plateaus and hot-side tails more faithfully. The framework integrates governing equations with data to deliver accurate swelling and stress predictions using only eight anchors and thirteen held-out points per case. These results position PINNs as a reliable surrogate for designing thermo-responsive hydrogels in soft actuators and biomedical systems. Full article

(This article belongs to the Special Issue Modelling of Deformation Characteristics of Materials or Structures)

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16 pages, 7554 KB

Open AccessArticle

Architecting Highly Anisotropic Thermal Conductivity in Flexible Phase Change Materials for Directed Thermal Management of Cylindrical Li-Ion Batteries

by Liying Chen, Tong Yang, Jun Jiang, Jianwen Luo, Yuanyuan Li, Juntao Wang, Wanwan Li and Sujun Guan

Materials 2025, 18(23), 5400; https://doi.org/10.3390/ma18235400 (registering DOI) - 30 Nov 2025

Abstract

The anisotropic jelly roll structure of cylindrical Li-ion batteries leads to highly directional heat generation, causing severe radial heat accumulation and creating a critical demand for precise thermal management. Conventional anisotropic phase change materials (PCMs), often reliant on single-dimensional conductive skeletons, exhibit limited [...] Read more.

The anisotropic jelly roll structure of cylindrical Li-ion batteries leads to highly directional heat generation, causing severe radial heat accumulation and creating a critical demand for precise thermal management. Conventional anisotropic phase change materials (PCMs), often reliant on single-dimensional conductive skeletons, exhibit limited enhancement in thermal conductivity anisotropy. This study proposes a novel strategy utilizing a hybrid carbon aerogel composed of one-dimensional carbon nanotubes (CNTs) and three-dimensional expanded graphite (EG) to construct highly aligned thermal conduction pathways within a flexible PCM. A three-step experimental method was employed to successfully fabricate a composite PCM with highly anisotropic thermal conductivity. A case study confirmed that, compared to a sole 3D skeleton, the hybrid 1D/3D aerogel significantly improves the alignment of the microstructure. At an optimal hybrid aerogel content of 8 wt.%, the composite achieved a 5.0% increase in radial thermal conductivity and a remarkable 16.7% increase in axial thermal conductivity, indicating a significantly optimized anisotropy ratio. When applied to a cylindrical battery thermal-management case, this material enables directed heat dissipation, effectively lowering the maximum battery-surface temperature by 13.1 °C. This work provides a scalable approach for designing high-performance anisotropic flexible PCMs tailored for advanced thermal management in high-power-density Li-ion batteries and other compact electronics. Full article

(This article belongs to the Section Energy Materials)

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22 pages, 7294 KB

Open AccessArticle

Multi-Objective Optimization of the Crashworthiness of Aluminum Circular Tubes with Graded Thicknesses

by Jie Ren, Shujie Liu, Xiangyu Dong and Changfang Zhao

Materials 2025, 18(23), 5399; https://doi.org/10.3390/ma18235399 (registering DOI) - 30 Nov 2025

Abstract

This study proposes a novel graded-thickness, thin-walled aluminum alloy (Al) circular tube energy-absorbing structure and conducts comprehensive parametric modeling and multi-objective optimization research. The 7050Al tube was selected for analysis of its energy absorption characteristics via numerical simulations and drop-weight impact tests. Through [...] Read more.

This study proposes a novel graded-thickness, thin-walled aluminum alloy (Al) circular tube energy-absorbing structure and conducts comprehensive parametric modeling and multi-objective optimization research. The 7050Al tube was selected for analysis of its energy absorption characteristics via numerical simulations and drop-weight impact tests. Through simulation calculations and drop hammer impact verification tests, the number and location of concertina lobes after crushing, as well as the force variation law of the structure during the crushing process, were analyzed. The results indicate that generating annular folds at the impact end can significantly enhance impact absorption and suppress structural instability. Drop-weight test results further validate the superior crashworthiness of the proposed 7050Al tube under dynamic loading conditions and confirm the accuracy of the numerical crushing model. To enable rapid and precise structural modifications, a Python-based parametric modeling framework has been developed. A fully automated parametric optimization workflow has been established within Isight to facilitate the efficient, multi-objective optimization of the structure’s design. This methodology provides a robust tool for designing customizable energy-absorbing structures with tailored crashworthiness performance. Full article

(This article belongs to the Section Mechanics of Materials)

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8 pages, 4778 KB

Open AccessCommunication

The Dynamic Recrystallization and α Texture Evolution of As-Sintered GNPs/TA15 Composites During Extrusion

by Zongan Li, Shuo Wu, Yongkang Fu, Jingxin Zhou, Liran Sun, Jiabin Hou, Chao Cui, Xiaocong Li and Zhikun Li

Materials 2025, 18(23), 5398; https://doi.org/10.3390/ma18235398 (registering DOI) - 30 Nov 2025

Abstract

During the initial extrusion stage of the as-sintered GNPs/TA15 composite, dislocations accumulated along the GNPs and grain boundaries, leading to the formation of a subgrain structure. As extrusion progressed, these subgrains underwent rotation and transformed into finer grains through dynamic recrystallization. This process [...] Read more.

During the initial extrusion stage of the as-sintered GNPs/TA15 composite, dislocations accumulated along the GNPs and grain boundaries, leading to the formation of a subgrain structure. As extrusion progressed, these subgrains underwent rotation and transformed into finer grains through dynamic recrystallization. This process resulted in significant grain refinement, with the average grain size decreasing from 3.04 μm to 1.30 μm. Concurrently, the Ti matrix adjacent to the GNPs initially flowed towards the GNPs and subsequently elongated along the extrusion direction (ED). Furthermore, the deformed α grains experienced slip along the {10

\bar{1}

0}⟨11

\bar{2}

0⟩ system, giving rise to the development of [10

\bar{1}

1]//ED and [20

\bar{2}

1]//ED α textures. This study elucidates the influence of GNPs on the microstructural evolution, particularly in terms of grain refinement and the formation of α textures, as a function of increasing extrusion ratios. Full article

(This article belongs to the Section Metals and Alloys)

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12 pages, 11726 KB

Open AccessArticle

Effect of Framework Material and Thermal Aging on Shear Bond Strength of Three Different Gingiva-Colored Composite Resins

by Saliha Cagla Incearik, Guliz Aktas, Diler Deniz, Mustafa Baris Guncu and Mutlu Özcan

Materials 2025, 18(23), 5397; https://doi.org/10.3390/ma18235397 (registering DOI) - 30 Nov 2025

Abstract

The purpose of this study was to evaluate the effect of different framework materials and thermal aging on the shear bond strength (SBS) of gingiva-colored composites used in fixed dental restorations. A total of 270 samples (10 × 10 × 2 mm³ [...] Read more.

The purpose of this study was to evaluate the effect of different framework materials and thermal aging on the shear bond strength (SBS) of gingiva-colored composites used in fixed dental restorations. A total of 270 samples (10 × 10 × 2 mm³) were prepared using titanium, zirconia, and modified polyetheretherketone (modified PEEK). Three gingiva-colored composites (Gradia Gum, Anaxgum, Nexco) were applied after surface polishing and sandblasting. All specimens were stored in water at 37 °C for 24 h, then half of each group was subjected to thermal aging consisting of 10,000 cycles at temperatures between 5 and 55 °C. SBS testing was performed using a universal testing machine with a crosshead speed of 1 mm/min. Bonding failures were analyzed under a stereomicroscope, and one sample from each group was examined using a scanning electron microscope. SBS data were analyzed using three-way ANOVA with composite type, framework material, and thermal aging as factors, followed by pairwise comparisons (SPSS 23.0; p < 0.05). The highest SBS was recorded for the zirconia framework combined with Gradia Gum, specifically in the group without thermal aging (p < 0.05), while the lowest was observed for zirconia combined with Nexco after thermal aging (p < 0.05). Adhesive failures were predominant in the modified PEEK groups, whereas mixed failures occurred more frequently in titanium and zirconia groups. Both composite type and framework material significantly influenced SBS values, with thermal aging having a detrimental effect across all groups. This study demonstrates that both framework material and composite type affect bond strength, with specimens not subjected to thermal aging maintaining better adhesion. Thermal cycling reduced SBS in all groups, although the extent varied by material combination. Full article

(This article belongs to the Special Issue Development and Research of New Dental Materials)

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12 pages, 5733 KB

Open AccessArticle

Effect of Crystal Structure Anisotropy on the Corrosion Characteristics of Metals in Liquid Lead: A Molecular Dynamics Simulation Study

by Na Liang, Bin Long, Zhangshun Ruan, Xiaogang Fu, Xusheng Zhang, Yajie He, Shenghui Lu and Lingzhi Chen

Materials 2025, 18(23), 5396; https://doi.org/10.3390/ma18235396 (registering DOI) - 30 Nov 2025

Abstract

This study investigated the compatibility of lead with distinct crystal planes of Fe with a body-centered cubic (bcc) crystal structure and Ni with a face-centered cubic (fcc) crystal structure using molecular dynamics (MD) simulation. It was found that corrosion anisotropy depends mainly on [...] Read more.

This study investigated the compatibility of lead with distinct crystal planes of Fe with a body-centered cubic (bcc) crystal structure and Ni with a face-centered cubic (fcc) crystal structure using molecular dynamics (MD) simulation. It was found that corrosion anisotropy depends mainly on the role of different crystal planes in regulating the spatial distribution of liquid lead. The essence of this regulation can be attributed to the interaction between the crystal plane and the liquid lead atoms. In consequence of the periodic arrangement of the crystal planes, the close-packed plane exhibits the highest atomic density and the widest interplanar distance. This configuration minimizes the interaction of the liquid lead atoms with the other crystal planes, thereby maximizing the regulatory effect on the distribution of the liquid lead atoms. The regulatory effect results in the formation of a regular layer-like distribution of the lead atoms, with a spacing between layers that is analogous to the crystal planes. This distribution mechanism effectively prevents the dissolution of atoms on the crystal surface into the liquid lead side by separating the atoms of the solid–liquid system from each other. Accordingly, for pure metals with a bcc crystal structure, corrosion resistance anisotropy indicates that the (111) plane is the most susceptible to corrosion, followed by the (001) plane, and the close-packed plane of (110) exhibits the most corrosion-resistant properties. As for fcc crystals, the corrosion resistance of the distinct planes is ordered as follows: (111) > (001) > (110). Full article

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

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11 pages, 6093 KB

Open AccessArticle

The Influence of Powder Composition and Hydrogen Consumption on the Structural, Corrosion and Tribological Characteristics of Fe-Cr-Al Coatings Obtained by Air Plasma Spraying

by Aidar Kengesbekov, Dastan Buitkenov, Garip Erdogan, Aiym Nabioldina and Sultan Komekov

Materials 2025, 18(23), 5395; https://doi.org/10.3390/ma18235395 (registering DOI) - 29 Nov 2025

Abstract

Fe-Cr-Al coatings were obtained by air plasma spraying (APS) from 85Fe-12Cr-3Al and 68Fe-26Cr-6Al powders at two hydrogen flow rates (8 and 13 L/min), which resulted in four deposition regimes (A1, A2, B1, B2). Stainless steel 20Kh13 (equivalent to AISI 420) was used as [...] Read more.

Fe-Cr-Al coatings were obtained by air plasma spraying (APS) from 85Fe-12Cr-3Al and 68Fe-26Cr-6Al powders at two hydrogen flow rates (8 and 13 L/min), which resulted in four deposition regimes (A1, A2, B1, B2). Stainless steel 20Kh13 (equivalent to AISI 420) was used as the substrate material. The microstructure of the coatings has a typical lamellar layering with molten and semi-molten particles. When the hydrogen flow rate is increased to 13 L/min, a denser and more homogeneous structure with reduced porosity is observed. X-ray phase analysis revealed the presence of metal and oxide phases (Fe,Cr), Fe₃O₄, FeO, Fe²⁺Cr₂O₄, which indicates partial oxidation of particles during the spraying process and stabilization of the structure. Electrochemical tests in 3.5% NaCl solution showed that the 85Fe-12Cr-3Al coatings are characterized by a corrosion potential of E_o ≈ −0.60…−0.67 V, a corrosion current density of i_o = (2.6–4.7) × 10⁻⁵ A/cm², and a corrosion rate of 0.30–0.55 mm/year, whereas the 68Fe-26Cr-6Al coatings exhibit lower values of i_o = (1.4–2.9) × 10⁻⁵ A/cm² and a corrosion rate of 0.17–0.34 mm/year, indicating the formation of a denser protective oxide film (Cr₂O₃ + Al₂O₃) and enhanced surface passivation. Tribological tests showed that 85Fe-12Cr-3Al coatings demonstrate more stable friction compared to 68Fe-26Cr-6Al, while for regime B2, after 180 m, an increase in the friction coefficient is observed, caused by brittleness and the local destruction of the oxide film. A comprehensive analysis of the results showed that increasing the hydrogen consumption to 13 L/min improves the density and corrosion–tribological characteristics of the coatings. Full article

(This article belongs to the Section Metals and Alloys)

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22 pages, 4140 KB

Open AccessArticle

Effect of Sampling Interval on Dependence Between Hybrid Parameters of Machined Surface Textures

by Pawel Pawlus, Rafal Reizer and Wieslaw Żelasko

Materials 2025, 18(23), 5394; https://doi.org/10.3390/ma18235394 (registering DOI) - 29 Nov 2025

Abstract

Surface topography affects the functional properties of machined surfaces. To assess these effects, special parameters were developed. Among them, the hybrid parameters rms. slope Sdq and the developed interfacial areal ratio Sdr are of high significance. However, these parameters are interrelated. Sdr can [...] Read more.

Surface topography affects the functional properties of machined surfaces. To assess these effects, special parameters were developed. Among them, the hybrid parameters rms. slope Sdq and the developed interfacial areal ratio Sdr are of high significance. However, these parameters are interrelated. Sdr can be estimated from Sdq using the special formula. The connections between these parameters were studied in this work depending on the sampling interval. Sixty-four surface topographies, after various machining treatments, were measured by white light interferometer Talysurf CCI Lite and analysed. The same measurement condition was performed for all surfaces. The application of the formula that interrelated the hybrid parameters was tested for different sampling intervals. It was found that the Sdq parameter was strongly linearly correlated with the Sdr parameter, independent of the sampling interval. The dependence between hybrid parameters had a nonlinear character. The estimation of the Sdr parameter based on the values of the Sdq parameter yielded very accurate results for smooth surfaces, independent of the sampling interval. Relative errors in estimating Sdq based on Sdr decreased as the sampling interval increased. High errors corresponded to surfaces with high roughness amplitude. A proposal was presented for sampling interval selection. Because hybrid parameters are interrelated, one parameter should be selected for the description of the areal surface texture. The Sdq parameter is recommended because of its lower sensitivity to measurement errors than the Sdr parameter. Full article

(This article belongs to the Special Issue Material Surface Topography Measurement, Analysis and Characterization (2nd Edition))

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20 pages, 7024 KB

Open AccessArticle

Broadband EMI Shielding Performance in Optically Transparent Flexible In₂O₃/Ag/In₂O₃ Thin Film Structures

by Anton S. Voronin, Sergey V. Nedelin, Nikita A. Zolotovsky, Igor A. Tambasov, Mstislav O. Makeev, Pavel A. Mikhalev, Bogdan A. Parshin, Evgenia L. Buryanskaya, Mikhail M. Simunin, Ilya V. Govorun, Ivan V. Podshivalov, Il`ya I. Bril`, Mikhail K. Khodzitskiy and Stas V. Khartov

Materials 2025, 18(23), 5393; https://doi.org/10.3390/ma18235393 (registering DOI) - 29 Nov 2025

Abstract

Transparent conductive electrodes that combine flexibility with effective electromagnetic interference (EMI) shielding are important for next-gen flexible electronics and 5G/6G communication devices. Achieving high optical transparency, low sheet resistance, and broadband shielding performance remains a sophisticated task. This work demonstrates a solution: the [...] Read more.

Transparent conductive electrodes that combine flexibility with effective electromagnetic interference (EMI) shielding are important for next-gen flexible electronics and 5G/6G communication devices. Achieving high optical transparency, low sheet resistance, and broadband shielding performance remains a sophisticated task. This work demonstrates a solution: the synthesis and comprehensive characterization of flexible In₂O₃/Ag/In₂O₃ (IAI) structures on polyethylene terephthalate substrates. The optimized structure with a 13.2 ± 1.1 nm silver interlayer achieves an incredible combination of properties: high optical transmittance (82.59% at 500 nm), low sheet resistance (6.4 ± 0.8 Ω/sq), and insignificant optical haze (1.04%). Broadband EMI shielding measurements from 10 MHz to 1 THz reveal a uniform shielding effectiveness of 25–30 dB across band from radiowave to terahertz. The IAI structures also show outstanding mechanical resilience, maintaining their electrical and shielding performance under repeated bending. This unique set of attributes positions IAI thin films as a prospective material for transparent EMI shielding in advanced telecommunications and flexible optoelectronics. Full article

(This article belongs to the Special Issue The Microstructures and Advanced Functional Properties of Thin Films)

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14 pages, 1458 KB

Open AccessArticle

Adsorption Mechanism of Short Hydrophobic Extended Anionic Surfactants at the Quartz–Solution Interface

by Linlin Zhang, Zhicheng Xu, Zhiqiang Jin, Wangjing Ma, Lei Zhang and Lu Zhang

Materials 2025, 18(23), 5392; https://doi.org/10.3390/ma18235392 (registering DOI) - 29 Nov 2025

Abstract

This study elucidates the interfacial adsorption behavior of a series of short-chain extended anionic surfactants C₈P_xE_yC (sodium ethylhexyl polyoxypropylene x-polyoxyethylene y-carboxylate) on quartz surfaces, with a focus on the regulatory role of polyoxyethylene (EO) and polyoxypropylene (PO) [...] Read more.

This study elucidates the interfacial adsorption behavior of a series of short-chain extended anionic surfactants C₈P_xE_yC (sodium ethylhexyl polyoxypropylene x-polyoxyethylene y-carboxylate) on quartz surfaces, with a focus on the regulatory role of polyoxyethylene (EO) and polyoxypropylene (PO) groups. The results indicate that there is a two-stage adsorption process for C₈P_xE_yC molecules on the quartz surface. In the first adsorption stage, C₈P_xE_yC molecules adsorb at the interface primarily via hydrogen bonding with their hydrophobic tails oriented to water and thereby reducing quartz hydrophilicity before the critical micelle concentration (CMC). The second adsorption stage appears at the CMC, and a saturated monolayer forms via hydrogen bonding. When further increasing the concentration, C₈P_xE_yC molecules interact with the pre-adsorbed monolayer by hydrophobic interactions to establish a loose bilayer structure. As the hydrophilic heads of C₈P_xE_yC orient to water, the surface hydrophilicity of quartz enhances after CMC. The PO/EO chain length critically governs the adsorption behavior of C₈P_xE_yC. Specifically, longer PO chains enhance the molecular size and hydrophobicity of C₈P_xE_yC, leading to a decreased saturation adsorption amount. Conversely, longer EO chains improve the hydrophilicity of C₈P_xE_yC, promoting C₈P_xE_yC molecules to stay in water and consequently decreasing the interfacial adsorption amount of C₈P_xE_yC. This structure–activity relationship of C₈P_xE_yC molecules guides the design of extended surfactants for applications requiring precise wettability control. Full article

(This article belongs to the Section Materials Chemistry)

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19 pages, 4640 KB

Open AccessArticle

Mechanical Performance of Wool-Reinforced Epoxy Composites: Tensile, Flexural, Compressive, and Impact Analysis

by Carlos Ruiz-Díaz, Guillermo Guerrero-Vacas and Óscar Rodríguez-Alabanda

Materials 2025, 18(23), 5391; https://doi.org/10.3390/ma18235391 (registering DOI) - 29 Nov 2025

Abstract

This study situates washed sheep-wool fibres as a sustainable reinforcement candidate for epoxy matrices and evaluates their mechanical response under tensile, flexural, compressive, and Charpy impact loading. The objective of this work is to assess whether short, washed sheep-wool fibres can function as [...] Read more.

This study situates washed sheep-wool fibres as a sustainable reinforcement candidate for epoxy matrices and evaluates their mechanical response under tensile, flexural, compressive, and Charpy impact loading. The objective of this work is to assess whether short, washed sheep-wool fibres can function as a sustainable reinforcement for epoxy matrices, and to identify optimal fibre length–content windows that improve mechanical behaviour for engineering applications. Moulded–machined specimens were produced with fibre lengths of 3, 6, and 10 mm and contents of 1.0–5.0 wt.%, depending on the test; neat epoxy served as the reference. In tension, selected formulations—particularly 10 mm/1.5 wt.%—showed simultaneous increases in ultimate stress and modulus relative to the neat resin, corresponding to gains of about 10% in ultimate tensile stress and 50% in tensile modulus, at the expense of ductility. In flexure, the modulus decreases by roughly 15–35% compared with the matrix, whereas configurations with 3–6 mm at 2.5–5 wt.% raise the fracture stress by about 35–45% and improve post-peak resistance. In compression, reinforcement markedly elevates yield stress, with increases of up to about 160% at 3 mm/2 wt.%, while the ultimate strain decreases moderately. In Charpy impact, all reinforced materials underperform the resin, with absorbed energy reduced by roughly 75–93% depending on fibre length and content, with 3 mm/1 wt.% being the least affected. A two-factor analysis of variance (ANOVA) indicates that fibre length primarily governs tensile and compressive behaviour, while fibre content dominates flexural and impact responses. Overall, the findings support wool fibres as a viable reinforcement when length and content are optimized, pointing to their use in non-structural to semi-structural industrial components such as interior panels, housings, casings, protective covers, and other parts where moderate tensile/compressive performance is sufficient and material sustainability is prioritised. Full article

(This article belongs to the Special Issue Advances in Polymer Blends and Composites—Second Edition)

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