Materials

11 pages, 1946 KiB

Open AccessFeature PaperArticle

Influence of Surface Treatments on the Pull-Off Performance of Adhesively Bonded Polylactic Acid (PLA) Specimens Manufactured by Fused Deposition Modeling (FDM)

by Gianluca Parodo, Giuseppe Moffa, Alessandro Silvestri, Luca Sorrentino, Gabriel Testa and Sandro Turchetta

Materials 2025, 18(17), 3965; https://doi.org/10.3390/ma18173965 (registering DOI) - 24 Aug 2025

Abstract

This study investigates the influence of different surface treatments (namely, mechanical abrasion and solvent cleaning with isopropyl alcohol and acetone) on the adhesive bonding performance of polylactic acid (PLA) substrates produced by Fused Deposition Modeling (FDM). Pull-off tests revealed that the isopropanol-cleaned specimens [...] Read more.

This study investigates the influence of different surface treatments (namely, mechanical abrasion and solvent cleaning with isopropyl alcohol and acetone) on the adhesive bonding performance of polylactic acid (PLA) substrates produced by Fused Deposition Modeling (FDM). Pull-off tests revealed that the isopropanol-cleaned specimens achieved the highest bond strength, with an average pull-off value exceeding 8.5 MPa, compared to approximately 5.6 MPa for untreated PLA. Conversely, acetone cleaning resulted in the lowest performance (about 3.5 MPa), while mechanical abrasion yielded intermediate values of about 6 MPa. FTIR analysis confirmed that no chemical reactions occurred, although acetone and abrasion induced significant physical surface changes, unlike isopropanol, which acted as an effective cleaning agent. These findings demonstrate that surface cleanliness plays a dominant role over morphological alterations in enhancing the adhesion of PLA-based 3D-printed joints. Full article

(This article belongs to the Special Issue Advanced Machining and Technologies in Materials Science)

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14 pages, 2228 KiB

Open AccessArticle

Silver Nanoparticles@Zeolite Composites: Preparation, Characterization and Antibacterial Properties

by Gospodinka Gicheva, Marinela Panayotova, Orlin Gemishev, Sergei A. Kulinich and Neli Mintcheva

Materials 2025, 18(17), 3964; https://doi.org/10.3390/ma18173964 (registering DOI) - 24 Aug 2025

Abstract

The presence of various Ag species (Ag⁺ ions, Ag clusters, and Ag nanoparticles (NPs)) in Ag-zeolite nanocomposites strongly influences their catalytic, photocatalytic, and antibacterial properties. To tailor materials for specific applications, it is essential to employ strategies that control the redox processes [...] Read more.

The presence of various Ag species (Ag⁺ ions, Ag clusters, and Ag nanoparticles (NPs)) in Ag-zeolite nanocomposites strongly influences their catalytic, photocatalytic, and antibacterial properties. To tailor materials for specific applications, it is essential to employ strategies that control the redox processes between Ag⁺ and Ag⁰ and facilitate the formation of active Ag-containing composites. In this study, we present a comparative analysis of Ag-zeolite nanocomposites, focusing on their synthesis methods, structural characteristics, and antibacterial activity against Escherichia coli. Ag NPs were synthesized using three approaches: solid-state thermal reduction, chemical reduction in aqueous solutions with a mild reducing agent (sodium citrate, Na₃Cit), and chemical reduction with a strong reducing agent (sodium borohydride, NaBH₄). The resulting materials were characterized by X-ray diffraction (XRD), diffuse reflectance UV–Vis spectroscopy (DR UV–Vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), while antibacterial activity was assessed using biological assays. Microscopic and spectroscopic analyses confirmed the formation of Ag NPs and the co-existence of immobilized Ag⁺ ions within the zeolite framework. The specific influence of the treatment method of Ag⁺-zeolite on the presence of silver species in the nanocomposites and their role in antibacterial properties were evaluated. The highest antibacterial efficiency was observed in the nanocomposite produced by thermal treatment of Ag-exchanged zeolite. Thus, the crucial function of Ag⁺ ions in the mechanism of bacteria cell death was suggested. Full article

(This article belongs to the Special Issue Research on Zeolites and Zeolite-Like Materials: Synthesis, Structure, Properties and Application)

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16 pages, 1852 KiB

Open AccessArticle

Evaluation of Constitutive Models for Low-Temperature Performance of High-Modulus Modified Asphalt: A BBR Test-Based Study

by Chao Pu, Bingbing Lei, Zhiwei Yang and Peng Yin

Materials 2025, 18(17), 3963; https://doi.org/10.3390/ma18173963 (registering DOI) - 24 Aug 2025

Abstract

High-modulus asphalt, with its excellent fatigue resistance and high-temperature resistance, is gradually becoming a preferred material for the development of durable asphalt pavements. However, its poor low-temperature performance has become one of the key bottlenecks restricting its wide application. In recent years, in-depth [...] Read more.

High-modulus asphalt, with its excellent fatigue resistance and high-temperature resistance, is gradually becoming a preferred material for the development of durable asphalt pavements. However, its poor low-temperature performance has become one of the key bottlenecks restricting its wide application. In recent years, in-depth analysis of the mechanism underlying the changes in the low-temperature performance of high-modulus asphalt has gradually become a research focus in the field of asphalt pavements. Accordingly, this study selected four representative high-modulus asphalts, conducted bending beam rheometer (BBR) tests to obtain their low-temperature creep parameters, and used three viscoelastic constitutive models to investigate their low-temperature constitutive relationships. Grey relational analysis (GRA) was further applied to evaluate the models. The results show that, when evaluating the low-temperature performance of high-modulus asphalt, the elastic and viscous parameters variation laws, for the three-parameter solid (TPS) model and four-parameter solid (FPS) model, are not obvious and have large fluctuations, and the accuracy of the fitting curves is relatively low, while the Burgers model has extremely high fitting accuracy, with small parameter fluctuations and significant regularity. The GRA model reveals that the Burgers model is more suitable than the TPS and FPS models for describing the low-temperature creep behavior of high-modulus asphalt, which further confirms the reliability of using the Burgers model to evaluate the low-temperature performance of high-modulus asphalt. Full article

(This article belongs to the Special Issue Advances in Road Materials and Pavement Design)

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26 pages, 3819 KiB

Open AccessArticle

Chemical Interactions of Deicing Salts with Concrete Pastes Containing Slag Cement

by Mohsen Torabi and Peter C. Taylor

Materials 2025, 18(17), 3962; https://doi.org/10.3390/ma18173962 (registering DOI) - 24 Aug 2025

Abstract

Chloride-based deicing salt solutions have been contacted with concrete pastes containing slag cement at different conditions, such as slag replacement (20–80%), type (CaCl₂, MgCl₂, NaCl), and concentration (1 M–5 M) of the deicing salt, as well as temperature (ambient [...] Read more.

Chloride-based deicing salt solutions have been contacted with concrete pastes containing slag cement at different conditions, such as slag replacement (20–80%), type (CaCl₂, MgCl₂, NaCl), and concentration (1 M–5 M) of the deicing salt, as well as temperature (ambient & −18 °C), and the extent of their reactions have been studied using XRD and ICP-OES. Also, solubility of Friedel salt (FS) has been measured in different types and concentrations of deicing salt solutions. It has been observed that the chemical deterioration arising from the formation and then dissolution of FS is more significant than the damage caused by the formation and expansion of oxychlorides in the pastes containing slag. While calcium oxychloride in its dried form can linger inside the paste for a long time, FS undergoes incongruent dissolution in CaCl₂ and MgCl₂ solutions and leaves the system. Presence of higher levels of AFm phases in pastes containing slag will further underscore this phenomenon. The extent of this chemical deterioration is relatively lower in NaCl solutions. Also, it was found that the nature of the chemical interaction changes with the concentration of the salt, as some disappeared phases might reappear and then disappear again. Using XRD and ICP-OES, this study provides a mechanistic understanding of salt-induced chemical deterioration in slag cement pastes by identifying phase-specific vulnerabilities and tracking the formation, transformation, and dissolution of key phases, such as Friedel’s salt and calcium oxychloride; additionally, the influence of various parameters have been studied, and chemical mechanisms have been proposed. Full article

(This article belongs to the Special Issue The Advanced Development in Concrete Materials: Properties and Construction Techniques)

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15 pages, 5342 KiB

Open AccessArticle

Transfer Learning-Based Multi-Sensor Approach for Predicting Keyhole Depth in Laser Welding of 780DP Steel

by Byeong-Jin Kim, Young-Min Kim and Cheolhee Kim

Materials 2025, 18(17), 3961; https://doi.org/10.3390/ma18173961 (registering DOI) - 24 Aug 2025

Abstract

Penetration depth is a critical factor determining joint strength in butt welding; however, it is difficult to monitor in keyhole-mode laser welding due to the dynamic nature of the keyhole. Recently, optical coherence tomography (OCT) has been introduced for real-time keyhole depth measurement, [...] Read more.

Penetration depth is a critical factor determining joint strength in butt welding; however, it is difficult to monitor in keyhole-mode laser welding due to the dynamic nature of the keyhole. Recently, optical coherence tomography (OCT) has been introduced for real-time keyhole depth measurement, though accurate results require meticulous calibration. In this study, deep learning-based models were developed to estimate penetration depth in laser welding of 780 dual-phase (DP) steel. The models utilized coaxial weld pool images and spectrometer signals as inputs, with OCT signals serving as the output reference. Both uni-sensor models (based on coaxial pool images) and multi-sensor models (incorporating spectrometer data) were developed using transfer learning techniques based on pre-trained convolutional neural network (CNN) architectures including MobileNetV2, ResNet50V2, EfficientNetB3, and Xception. The coefficients of determination values (R²) of the uni-sensor CNN transfer learning models without fine-tuning ranged from 0.502 to 0.681, and the mean absolute errors (MAEs) ranged from 0.152 mm to 0.196 mm. In the fine-tuning models, R² decreased by more than 17%, and MAE increased by more than 11% compared to the previous models without fine-tuning. In addition, in the multi-sensor model, R² ranged from 0.900 to 0.956, and MAE ranged from 0.058 mm to 0.086 mm, showing better performance than uni-sensor CNN transfer learning models. This study demonstrated the potential of using CNN transfer learning models for predicting penetration depth in laser welding of 780DP steel. Full article

(This article belongs to the Special Issue Advances in Plasma and Laser Engineering (Second Edition))

16 pages, 2954 KiB

Open AccessArticle

The Influence of Two-Region Morphology and Grain Shape on the Transport Critical Current Density in the Range from 15 K to 30 K in SiC-Doped MgB₂ Wires Fabricated by the Powder-in-Tube Method

by Daniel Gajda, Michał Babij, Andrzej Zaleski, Dogan Avci, Hakan Yetis, Ibrahim Belenli, Fırat Karaboga, Damian Szymanski and Tomasz Czujko

Materials 2025, 18(17), 3960; https://doi.org/10.3390/ma18173960 (registering DOI) - 24 Aug 2025

Abstract

The paper presents the results of the influence of SiC dopant, annealing temperature, and annealing time on the morphology of MgB₂ material in superconducting wires. The results of measurements of critical temperature (T_c), irreversible magnetic field (B_irr [...] Read more.

The paper presents the results of the influence of SiC dopant, annealing temperature, and annealing time on the morphology of MgB₂ material in superconducting wires. The results of measurements of critical temperature (T_c), irreversible magnetic field (B_irr), resistance in the normal state (R_n), and transport critical current density (J_ct) at the temperature range from 15 K to 30 K are presented. The MgB₂ material is characterized by the presence of two specific regions. The first region with high density, excess Mg, and rectangular MgB₂ grains is located outside the voids surrounding them. The second region occurs inside the ceramic core, away from voids, and its chemical composition corresponds to a stoichiometric Mg to B ratio (1:2), and it is characterized by the presence of spherical grains and lower material density. A higher amount of SiC admixtures (6 at.%) causes an increase in the first region surface area. This kind of structure observation in MgB₂ superconducting wires has never been reported previously. The transport measurements showed that higher SiC dopant leads to lower J_ct at higher temperatures and high magnetic fields. The studies showed that the point-dominant mechanism and the first region allow for obtaining high J_ct at 30 K. Full article

(This article belongs to the Special Issue Advanced Superconducting Materials and Technology)

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17 pages, 4396 KiB

Open AccessArticle

Effect of the Different Growth Shapes on the Electrochemical Behavior of Ti Thin Films for Medical Applications

by Matteo Bertapelle, Joel Borges, Julia Claudia Mirza-Rosca and Filipe Vaz

Materials 2025, 18(17), 3959; https://doi.org/10.3390/ma18173959 (registering DOI) - 24 Aug 2025

Abstract

The response of titanium (Ti) thin films is closely related to their microstructure, which is extremely sensitive to the selected deposition parameters and geometrical configurations. The present study investigates the impact of geometrical factors on the growth of Ti thin films, focusing on [...] Read more.

The response of titanium (Ti) thin films is closely related to their microstructure, which is extremely sensitive to the selected deposition parameters and geometrical configurations. The present study investigates the impact of geometrical factors on the growth of Ti thin films, focusing on how variations in growth geometry influence film microstructure, surface morphology, and corrosion resistance. Three Ti thin films were prepared using Glancing Angle Deposition (GLAD) in a custom-built DC reactive magnetron sputtering system. For the first sample, the target was positioned perpendicular to the substrate surface (α = 0°); for the second and third samples, the substrate holder was positioned at an angle of 85° regarding the target direction (α = 85°), incorporating a 180° azimuthal rotation for the last (to obtain a zigzag-like deposition). The thickness and morphological features of the thin films were investigated by SEM, while the surface morphology, specifically roughness, and crystallinity of the thin films were assessed by AFM and XRD, respectively. Continuous and alternating current techniques were used for electrochemical characterization of behavior in simulated body fluid. The obtained results show a clear tendency to an improvement in anticorrosion performances varying the nanoarchitecture of the films in comparison to the conventional-grown sample, with the inclined sample presenting a slight enhancement in corrosion resistance and the zigzag-grown sample having the best corrosion resistance properties of the three. Full article

(This article belongs to the Section Metals and Alloys)

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Graphical abstract

13 pages, 2049 KiB

Open AccessArticle

Negative Mass in the Systems Driven by Entropic Forces

by Edward Bormashenko, Artem Gilevich and Shraga Shoval

Materials 2025, 18(17), 3958; https://doi.org/10.3390/ma18173958 (registering DOI) - 24 Aug 2025

Abstract

The paper addresses the phenomena of negative effective mass and negative effective density emerging in systems driven by entropic elastic forces. The elasticity of polymers is, at least partially, of entropic origin, and it represents the tendency of a polymer to evolve into [...] Read more.

The paper addresses the phenomena of negative effective mass and negative effective density emerging in systems driven by entropic elastic forces. The elasticity of polymers is, at least partially, of entropic origin, and it represents the tendency of a polymer to evolve into a more probable state, rather than into one of lower potential energy. Entropy forces are temperature-dependent; thus, the temperature dependence of the effective mass and effective density arises. The effect of the negative effective mass is a resonance effect, emerging in core–shell mechanical systems, which takes place when the frequency of the harmonic external force acting on a core–shell system connected by an ideal spring approaches from above to the eigen-frequency of the system. We address the situation when the ideal spring connecting the core to the shell is made from a polymer material, and its elasticity is of an entropic origin. The effective mass is calculated, and it is temperature-dependent. The chain of core–shell units connected with a polymer spring is studied. The effective density of the spring is temperature-dependent. Optical and acoustical branches of vibrations are elucidated. The negative mass and density become attainable under the variation of the temperature of the system. In the situation when only one of the springs demonstrates temperature dependence, entropic behavior is investigated. Exemplifications of the effect are addressed. Full article

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25 pages, 9654 KiB

Open AccessArticle

Comprehensive Quality Assessment of Refractory Materials Used in Aluminum Production

by Miriam Andrejiova, Štefan Markulik, Miriama Pinosova and Marek Šolc

Materials 2025, 18(17), 3957; https://doi.org/10.3390/ma18173957 (registering DOI) - 24 Aug 2025

Abstract

Corrosion of refractory materials in NaCl–KCl melts is a major issue affecting the service life of linings in aluminum metallurgy, where these salts serve as the basis for covering and refining mixtures. The aim of this study was to comprehensively evaluate the corrosion [...] Read more.

Corrosion of refractory materials in NaCl–KCl melts is a major issue affecting the service life of linings in aluminum metallurgy, where these salts serve as the basis for covering and refining mixtures. The aim of this study was to comprehensively evaluate the corrosion resistance of alumina-silicate refractory materials (ASRM) with a high SiO₂/Al₂O₃ ratio in contact with melts of varying NaCl–KCl ratios. Static crucible corrosion tests were conducted in accordance with the technical specification CEN/TS 15418:2006. Macro- and microscopic analysis, chemical analysis (AAS), and semi-quantitative EDX analysis enabled detailed monitoring of the depth of melt infiltration, microstructural changes, and element distribution within the material. The results demonstrated that as the NaCl content in the melt increased, there was a significant rise in both the depth of infiltration and the degree of material degradation. A linear regression model confirmed a very strong positive correlation between NaCl content and the extent of damage (R² = 0.967). Chemical analysis revealed that the silicon content decreases in the infiltrated zone, while aluminum remains stable, indicating superior corrosion resistance of Al₂O₃ compared to SiO₂. EDX analysis also confirmed increased concentrations of sodium and chlorine in the infiltrated areas, complementing the AAS results and providing more precise mapping of the distribution of corrosion products within the material structure. These findings provide a quantitative basis for optimizing the composition of refractory materials and designing protective strategies to extend their service life under the aggressive operating conditions of aluminum production. Full article

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25 pages, 8540 KiB

Open AccessArticle

Effect of Pitch Angle on the Strength of a TC4/Helicoidal Composite Double-Bolt Scarf Joint: A Numerical Study

by Chunhua Wan, Xin Du, Guofan Zhang, Zhefeng Yu and Xin Lian

Materials 2025, 18(17), 3956; https://doi.org/10.3390/ma18173956 (registering DOI) - 24 Aug 2025

Abstract

A progressive damage model was developed to study the damage and failure behavior of CFRP/Ti double-bolt scarf joints under quasi-static loading. The three-dimensional Hashin failure criterion was integrated into a finite element model via the ABAQUS user-defined material subroutine. Quasi-static tensile tests were [...] Read more.

A progressive damage model was developed to study the damage and failure behavior of CFRP/Ti double-bolt scarf joints under quasi-static loading. The three-dimensional Hashin failure criterion was integrated into a finite element model via the ABAQUS user-defined material subroutine. Quasi-static tensile tests were conducted to investigate failure mechanisms and validate the model. The predicted failure modes match the experimental results with an error of 11.8% in the prediction of ultimate load. The effect of helicoidal layup on the composite joint was studied for the application of a helicoidal composite. The results show that the helicoidal layup configuration with a 45/−45 layup on the surface had the highest failure load, and the helicoidal layup introduced more tensile damage in the matrix. This study offers practical failure prediction methods and comprehensive failure mode analysis for composite bolted scarf joints. Full article

(This article belongs to the Special Issue Advanced Composite Materials for Multifunctional Applications: Design, Fabrication, and Performance Optimization)

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27 pages, 7518 KiB

Open AccessReview

Advances in Wire EDM Technology for Cutting Silicon Carbide Ceramics: A Review

by Mohammad Ghasemian Fard, Jana Petru and Sergej Hloch

Materials 2025, 18(17), 3955; https://doi.org/10.3390/ma18173955 (registering DOI) - 23 Aug 2025

Abstract

Silicon carbide (SiC) ceramics have gained significant attention in advanced engineering applications because of their superior mechanical properties, resistance to wear and corrosion, and thermal stability. However, the precision machining of these materials is extremely challenging because of their intrinsic hardness and brittleness. [...] Read more.

Silicon carbide (SiC) ceramics have gained significant attention in advanced engineering applications because of their superior mechanical properties, resistance to wear and corrosion, and thermal stability. However, the precision machining of these materials is extremely challenging because of their intrinsic hardness and brittleness. Wire Electrical Discharge Machining (WEDM) has become increasingly popular as a viable technique for processing SiC ceramics because of its ability to produce intricate geometries and high-quality surface finishes. In this review paper, a comprehensive overview of WEDM technology applied to SiC ceramics is presented, emphasizing the influence of process parameters, wire materials, and dielectric fluids on cutting efficiency and quality. This research explores recent experimental findings related to Wire Electrical Discharge Machining (WEDM) and highlights the challenges in reducing material damage. It also presents strategies to improve machining performance. Additionally, potential future directions are discussed, providing a roadmap for further research and the application of WEDM in processing silicon carbide (SiC) and its variants, including solid silicon carbide (SSiC) and silicon-infiltrated silicon carbide (SiSiC). Full article

(This article belongs to the Special Issue Non-conventional Machining: Materials and Processes)

25 pages, 4294 KiB

Open AccessArticle

The Investigation of Shear Fracture Toughness and Structure of ITZ of Limestone Concrete with Different Aggregate Grain Size

by Grzegorz Ludwik Golewski

Materials 2025, 18(17), 3954; https://doi.org/10.3390/ma18173954 (registering DOI) - 23 Aug 2025

Abstract

Due to the shortage of construction aggregates, carbonate rock aggregates—including mainly limestone aggregates—have long been used in structural concrete in many countries worldwide. On the other hand, earlier tests on the shear fracture toughness of concretes with limestone aggregates were very limited and [...] Read more.

Due to the shortage of construction aggregates, carbonate rock aggregates—including mainly limestone aggregates—have long been used in structural concrete in many countries worldwide. On the other hand, earlier tests on the shear fracture toughness of concretes with limestone aggregates were very limited and were even abandoned for many years. For the above reasons, in this paper, completely new fracture toughness tests were performed according to the mode II fracture for limestone concretes with different grain size distributions. Two types of aggregate grain were used, i.e., two with maximum grain sizes of 8 mm (M1 series concrete) and 16 mm (M2 series concrete). During the experiments, the critical stress-intensity factor (K_IIc) and critical unit work of failure (J_IIc) were determined. Based on the conducted studies, it was found that higher values of fracture mechanics parameters were noted as the grain sizes of the aggregate used increased. The increases in the analyzed fracture mechanics parameters were noticeably greater in the M2 series concrete compared to the results for the M1 series concrete, specifically by 27% for K_IIc and 35% for J_IIc. In addition to macroscopic tests, detailed microstructural analyses of the ITZ area between the coarse aggregate grains and the cement matrix were conducted. Based on the captured images, it was determined that, in the M1 series concrete, the contacts between the aggregate grains and the cement paste exhibit a loose structure with visible microcracks. In contrast, the M2 series concrete showed no visible damages within the ITZ area itself nor at their displacement at a distance of approximately a few μm away from this area. This microstructure of both materials resulted in the M1 series concrete being more prone to rapid and sudden fracture propagation, leading to its brittle behavior during the fracture process. In contrast, the large, well-developed limestone aggregate grains in the M2 series concrete facilitated improved stress transfer beyond the ITZ area into the cement matrix, preserving the continuity of the material structure and consequently leading to quasi-plastic behavior of the concrete during the fracture process. The novelty and utilitarianism of the research undertaken result from the fact that exploring the properties of concretes with limestone aggregates using mode II fracture is an important aspect of evaluating the durability and safety of concrete structures subjected mainly to shear forces. Full article

(This article belongs to the Special Issue Structural, Physical and Mechanical Properties of Reinforced Concrete, Novel Cementitious Composites and Other Brittle Construction Materials)

13 pages, 2674 KiB

Open AccessReview

An Insight into Compositionally Complex Carbide Ceramic Coatings

by J. G. Lopes and J. P. Oliveira

Materials 2025, 18(17), 3953; https://doi.org/10.3390/ma18173953 (registering DOI) - 23 Aug 2025

Abstract

Ceramic carbide coatings function as protecting components when subjected to extreme mechanical and/or high-temperature conditions. In this regard, the literature emphasizes that the compositionally complex design concept can be employed to improve the ceramic coating properties via compositional tuning, similarly to high-entropy alloys. [...] Read more.

Ceramic carbide coatings function as protecting components when subjected to extreme mechanical and/or high-temperature conditions. In this regard, the literature emphasizes that the compositionally complex design concept can be employed to improve the ceramic coating properties via compositional tuning, similarly to high-entropy alloys. At this moment, such studies are mainly based on the development of tribological coatings to obtain durable and low-friction surface barriers and to produce ablation-resistant barriers by forming stable oxide scales with self-healing mechanisms. Moreover, it can also be observed that the integration of computational design methods to predict and accelerate the discovery of optimized compositionally complex carbide ceramic coating systems is a viable possibility. Full article

(This article belongs to the Special Issue Advanced Functional Coatings for Surface Engineering: Deposition, Properties and Applications)

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21 pages, 4351 KiB

Open AccessFeature PaperArticle

Sustainable PLA Composites Filled with Poaceae Fibers: Thermal, Structural, and Mechanical Properties

by Natalia Kubiak, Bogna Sztorch, Magdalena Kustosz, Miłosz Frydrych, Daria Pakuła, Marek Jałbrzykowski, Tobias Hartmann, Camilo Zopp, Lothar Kroll and Robert E. Przekop

Materials 2025, 18(17), 3952; https://doi.org/10.3390/ma18173952 (registering DOI) - 23 Aug 2025

Abstract

The present study investigates the manufacturing and characterization of poly(lactic acid) (PLA)-based composites with raw and treated Poaceae, with loadings of 5, 10, and 20% wt. Before composite fabrication, the lignocellulosic fillers were analyzed using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), [...] Read more.

The present study investigates the manufacturing and characterization of poly(lactic acid) (PLA)-based composites with raw and treated Poaceae, with loadings of 5, 10, and 20% wt. Before composite fabrication, the lignocellulosic fillers were analyzed using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and microscopy to assess their chemical composition, thermal stability, and morphological features. Composites were prepared by melting PLA in a molten state with fillers, followed by injection molding. Comprehensive characterization of the obtained composites included microscopic analysis, melt flow index (MFI) testing, and differential scanning calorimetry (DSC), as well as mechanical tests (tensile and bending tests, impact test). The addition of Poaceae fibers to the PLA matrix significantly affected the mechanical and rheological properties of the composites. Incorporating 5% of cooked or alkalized fibers increased the flexural strength by 57% and 54%, respectively, compared to neat PLA. The modulus of elasticity for the composite with 20% alkalized fibers increased by as much as 35%. The fibers acted as nucleating agents, reducing the cold crystallization temperature (T_cc) by up to 15.6 °C, while alkaline residues contributed to an increased melt flow index (MFI). The conducted research provides a valuable basis and insights into the design of sustainable bio-based composites. Full article

(This article belongs to the Special Issue Mechanical Properties and Modeling of Structural Composites)

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25 pages, 8057 KiB

Open AccessArticle

Experimental and Numerical Investigations on the Influences of Target Porosity and w/c Ratio on Strength and Permeability of Pervious Concrete

by Fei Liu, Zhe Li, Bowen Liu, Zhuohui Yu, Zetong Li, Mengyuan Zhu, Yanjie Wang and Xizhou Ding

Materials 2025, 18(17), 3951; https://doi.org/10.3390/ma18173951 (registering DOI) - 22 Aug 2025

Abstract

Pervious concrete is a promising sustainable pavement material for sponge city construction. The incorporation of Steel Slag Aggregate (SSA) as a substitute for natural aggregates has the double role of clean production with significant economic and environmental benefits. While the strength and permeability, [...] Read more.

Pervious concrete is a promising sustainable pavement material for sponge city construction. The incorporation of Steel Slag Aggregate (SSA) as a substitute for natural aggregates has the double role of clean production with significant economic and environmental benefits. While the strength and permeability, known as two critical design parameters of pervious concrete, are closely linked to its porosity, there is limited research on the influence of the porosity on the mechanical properties of pervious concrete. In this paper, both experimental and numerical investigations were performed, focusing on the influence of target porosity on the strength and permeability of pervious concrete with and without SSA. Three different target porosities (15%, 20%, and 25%), five distinct water-to-cement (w/c) ratios (0.25, 0.28, 0.30, 0.33, and 0.35), and five SSA replacement ratios (0, 25%, 50%, 75%, and 100%) were considered in this study. A two-dimensional (2D) finite-element (FE) model was developed, with which the failure mode and the strength variation of pervious concrete under different target porosities were analyzed and verified with the experimental results. The results showed that the porosity had a significant influence on both the strength and permeability of pervious concrete, while the influence of the w/c ratio is marginal. There existed an optimal w/c ratio of 0.3, for which pervious concrete with porosities of 15%, 20%, and 25% achieved 28-day compressive strengths of 27.8, 20.6, and 15.6 MPa and permeability coefficients of 0.32, 0.58, and 1.02 cm/s, respectively. Specifically, at the lowest porosity of 15%, the replacement of 100% SSA resulted in the largest improvement in the compressive strength up to 37.86%. Based on the regression analysis, a series of empirical equations correlating the porosity, strength and permeability of pervious concrete was formulated and validated against the experimental data. The findings presented herein are expected to provide references to the practical evaluation of the optimal mix proportion of previous concrete, considering specific and demanding engineering requirements. Full article

(This article belongs to the Special Issue Cracking Risks in Blended Cement-Based Concrete: Mechanisms, Evaluation and Control)

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20 pages, 6859 KiB

Open AccessArticle

Experimental Investigation of Thermal Conductivity of Selected 3D-Printed Materials

by Maria Tychanicz-Kwiecień, Sebastian Grosicki and Marek Markowicz

Materials 2025, 18(17), 3950; https://doi.org/10.3390/ma18173950 - 22 Aug 2025

Abstract

This study presents the results of experimental studies on the thermal conductivity of specimens made from selected pure polymer filaments manufactured with the use of FFF 3D-printing technology. The tested samples were made of polylactic acid (PLA), polyethylene terephthalate glycol (PET-G), and acrylonitrile [...] Read more.

This study presents the results of experimental studies on the thermal conductivity of specimens made from selected pure polymer filaments manufactured with the use of FFF 3D-printing technology. The tested samples were made of polylactic acid (PLA), polyethylene terephthalate glycol (PET-G), and acrylonitrile butadiene styrene (ABS). In particular, the effects of the infill patterns and infill density on the tested samples were examined in order to characterize the influence of these parameters on the materials’ effective thermal conductivity. Honeycomb and grid infill patterns of the tested samples with infill densities of 40%, 60%, 80%, and 100% were examined. The influence of temperature on thermal conductivity was studied as well. Thermal conductivity was measured using the guarded heat flow method, according to the ASTM E1530 standard within the defined temperature ranges of 20–60 °C for ABS and PET-G and 20–50 °C for PLA material. Samples of the tested materials were manufactured with the use of the Fused Filament Fabrication method (FFF), and filaments with a uniform black color were used. The obtained results were analyzed in terms of thermal conductivity variation after samples’ infill pattern and infill density modifications, which provides extended thermal property characterization of the polymeric filaments adopted for 3D printing. Full article

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21 pages, 7441 KiB

Open AccessArticle

Nanoparticle-Reinforced Electroless Composite Coatings for Pipeline Steel: Synthesis and Characterization

by Biplab Baran Mandal, Vikash Kumar, Sovan Sahoo, Buddhadeb Oraon and Sumanta Mukherjee

Materials 2025, 18(17), 3949; https://doi.org/10.3390/ma18173949 - 22 Aug 2025

Abstract

Protective coatings are essential for extending the service life of components exposed to harsh conditions, such as pipes used in industrial systems, where wear and corrosion remain constant challenges. This study explores the development of a nano-sized TiO₂-reinforced electroless nickel-based ternary [...] Read more.

Protective coatings are essential for extending the service life of components exposed to harsh conditions, such as pipes used in industrial systems, where wear and corrosion remain constant challenges. This study explores the development of a nano-sized TiO₂-reinforced electroless nickel-based ternary (Ni-W-P) alloy and composite coating on API X60 steel, a high-strength carbon steel pipe grade widely used in oil and gas pipelines, using an alkaline hypophosphite-reduced bath. The surface morphology, microstructure, elemental composition, structure, phase evolution, adhesion, and roughness of the coatings were analyzed using optical microscopy, FESEM, EDS, XRD, AFM, cross-cut tape test, and 3D profilometry. The tribological performance was evaluated via Vickers microhardness measurements and reciprocating wear tests conducted under dry conditions at a 5 N load. The TiO₂ nanoparticle-reinforced composite coating achieved a consistent thickness of approximately 24 µm and exhibited enhanced microhardness and reduced coefficient of friction (COF), although the addition of nanoparticles increased surface roughness (S_a). Annealing the electroless composites at 400 °C led to a significant improvement in their tribological properties, primarily owing to the grain growth, phase transformation, and Ni₃P crystallization. XRD analysis revealed phase evolution from an amorphous state to crystalline Ni₃P upon annealing. Both the alloy and composite coatings exhibited excellent adhesion performances. The combined effect of TiO₂ nanoparticles, tungsten, and Ni₃P crystallization greatly improved the wear resistance, with abrasive and adhesive wear identified as the dominant mechanisms, making these coatings well suited for high-wear applications. Full article

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

13 pages, 5192 KiB

Open AccessArticle

Surface Hardening of Zr-1.0Sn-1.0Nb-0.3Fe Alloy Induced by Laser Surface Remelting

by Zhien Ning, Fangli Zhang, Lu Wu, Wei Zhang, Jijun Yang, Xiaotong Zhao and Linjiang Chai

Materials 2025, 18(17), 3948; https://doi.org/10.3390/ma18173948 - 22 Aug 2025

Abstract

To enhance surface hardness, laser surface remelting (LSR) was performed to treat the surface of a novel nuclear-grade Zr-1.0Sn-1.0Nb-0.3Fe zirconium alloy. A combination of advanced characterization techniques was used to systematically analyze the microstructural features of the samples before and after the LSR [...] Read more.

To enhance surface hardness, laser surface remelting (LSR) was performed to treat the surface of a novel nuclear-grade Zr-1.0Sn-1.0Nb-0.3Fe zirconium alloy. A combination of advanced characterization techniques was used to systematically analyze the microstructural features of the samples before and after the LSR treatment, and their correlation with hardness variations was studied. Results show that the LSR-treated surface consists of two distinct microstructural regions: (i) the remelted zone (RZ), characterized by fine lath structures and precipitates distributed along the lath boundaries; and (ii) the heat-affected zone, comprising blocky α phase, α laths, and precipitates. The surface of the LSR-treated samples exhibits a random texture, which is attributed to the selection suppression of α variants during the laser-induced rapid transformation. The average hardness of the RZ reaches 285.7 ± 8.3 HV, ~40% higher than the substrate. This hardness enhancement is ascribed to LSR-induced grain refinement. Full article

(This article belongs to the Section Metals and Alloys)

21 pages, 8415 KiB

Open AccessArticle

In Situ Constructing Highly Aligned Ribbon-like PHBV Lamellae in PBAT: Towards Strong, Ductile and High-Barrier PBAT/PHBV Films

by Yaqiao Wang, Jun Xu and Baohua Guo

Materials 2025, 18(17), 3947; https://doi.org/10.3390/ma18173947 - 22 Aug 2025

Abstract

This study presents a facile approach to fabricate PBAT/PHBV films with superior mechanical and barrier properties by in situ forming ribbon-like lamellae, achieving a PHBV platelet-reinforced PBAT films. The fabrication involves melt blending of PBAT and PHBV, where styrene–methyl methacrylate–glycidyl methacrylate copolymer as [...] Read more.

This study presents a facile approach to fabricate PBAT/PHBV films with superior mechanical and barrier properties by in situ forming ribbon-like lamellae, achieving a PHBV platelet-reinforced PBAT films. The fabrication involves melt blending of PBAT and PHBV, where styrene–methyl methacrylate–glycidyl methacrylate copolymer as a multifunctional reactive compatibilizer (RC) regulates PHBV domain size by forming a branched/cross-linked PBAT-B-PHBV structure. The introduction of a compatibilizer into the PBAT/PHBV system can reduce domain size and improve interfacial adhesion, thereby elevating PBAT’s storage modulus and complex viscosity for optimized blow-molding processability. During blow-molding, biaxial stretching with rapid cooling transforms PHBV sea–island structures into well-aligned ribbon-like lamellae. Notably, when PHBV content is ≤30 wt.%, lamellae form in the PBAT matrix, significantly enhancing both mechanical and barrier properties. The addition of RC reduces the lateral dimensions of PHBV lamellae while increasing PHBV number density. The introduction of 0.2 wt.% RC optimizes lamellar dimensions and density to maximize permeation pathway tortuosity. Ultimately, the lamellae in the PBAT matrix yield remarkable property enhancements: yield strength increased by >600%, elastic modulus by >200%, and water vapor/oxygen transmission rate reduced by ~81% and ~85%, respectively. Full article

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

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15 pages, 1934 KiB

Open AccessArticle

Development of Alternative Porous Magnesium Potassium Phosphate Cements as Thermal Insulating Materials

by Jessica Giro-Paloma, Jofre Mañosa, Alex Maldonado-Alameda, Anna Alfocea-Roig, Sergio Huete-Hernández, Josep Maria Chimenos and Joan Formosa

Materials 2025, 18(17), 3946; https://doi.org/10.3390/ma18173946 - 22 Aug 2025

Abstract

Magnesium potassium phosphate cement (MKPC), a type of chemically bonded phosphate ceramic (CBPC), presents a promising alternative to ordinary Portland cement (OPC). This study focuses on developing sustainable MKPC (sust-MKPC) as a thermally passive material for building applications. A low-grade magnesium oxide (LG-MgO) [...] Read more.

Magnesium potassium phosphate cement (MKPC), a type of chemically bonded phosphate ceramic (CBPC), presents a promising alternative to ordinary Portland cement (OPC). This study focuses on developing sustainable MKPC (sust-MKPC) as a thermally passive material for building applications. A low-grade magnesium oxide (LG-MgO) industrial by-product was utilized to formulate sust-MKPC, with hydrogen peroxide employed as an air-entraining agent (AEA) to induce high porosity and enhance thermal insulation while supporting sustainability goals by reducing energy consumption in climate control systems. Seven formulations incorporating varying hydrogen peroxide contents (0, 1, 2, 3, 5, 7.5, and 10 wt.%) were prepared to evaluate the impact of AEA on the thermal and physicomechanical properties. Comprehensive characterization, including porosity and thermal conductivity measurements, revealed that increasing the AEA content significantly improved thermal inertia and lowered thermal conductivity due to porosity. However, this enhancement was accompanied by a marked reduction in mechanical strength and density, highlighting the trade-off between thermal performance and structural integrity in porous sust-MKPC formulations. Full article

(This article belongs to the Special Issue New Thermal Insulation Materials in Green Buildings)

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13 pages, 2879 KiB

Open AccessArticle

Reoxidation of IF Steel Caused by Cr₂O₃-Based Stuffing Sand and Its Optimization

by Chenhui Wu, Youquan Peng, Jiqing Zhang, Jianhua Zhang and Xin Xie

Materials 2025, 18(17), 3945; https://doi.org/10.3390/ma18173945 - 22 Aug 2025

Abstract

Stuffing sand, as a critical auxiliary material, plays an important role in ladle teeming during the continuous casting process and is closely related to steel cleanliness. Based on thermodynamic calculations, a melting test in a vacuum induction furnace, and industrial statistical data analysis, [...] Read more.

Stuffing sand, as a critical auxiliary material, plays an important role in ladle teeming during the continuous casting process and is closely related to steel cleanliness. Based on thermodynamic calculations, a melting test in a vacuum induction furnace, and industrial statistical data analysis, the reoxidation of IF steel caused by conventional Cr₂O₃-based stuffing sand was investigated. The results show that Cr₂O₃-based stuffing sand is one of the main factors resulting in the reoxidation of IF steel. [Al] and [Ti] in IF steel can be oxidized by FeO, Cr₂O₃, and SiO₂ from the Cr₂O₃-based stuffing sand, which leads to the mass burning loss of [Al] and [Ti], thus resulting in the deterioration of steel cleanliness. After reoxidation caused by Cr₂O₃-based stuffing sand, the [Cr] content in IF steel increases by 70 ppm on average. To avoid reoxidation pollution by conventional Cr₂O₃-based stuffing sand, a new kind of Al₂O₃-based stuffing sand with low reactivity was developed and applied in industrial production. After adopting this new kind of stuffing sand, the burning loss of [Al] and [Ti] decreases by 41.3% and 24.2%, respectively, and the total oxygen content (T.[O]) of the steel in the tundish decreases by 35.2% compared with the conventional Cr₂O₃-based stuffing sand. Full article

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

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18 pages, 1789 KiB

Open AccessArticle

Flow Field Simulation and Experimental Study of Electrode-Assisted Oscillating Electrical Discharge Machining in the C_f-ZrB₂-SiC Micro-Blind Hole

by Chuanyang Ge, Sirui Gong, Junbo He, Kewen Wang, Jiahao Xiu and Zhenlong Wang

Materials 2025, 18(17), 3944; https://doi.org/10.3390/ma18173944 - 22 Aug 2025

Abstract

In the micro-EDM blind-hole machining of C_f-ZrB₂-SiC ceramics, defects such as bottom surface protrusion and machining fillets are often encountered. The implementation of an electrode-assisted oscillating device has proven effective in improving machining outcomes. To unravel the fundamental reasons [...] Read more.

In the micro-EDM blind-hole machining of C_f-ZrB₂-SiC ceramics, defects such as bottom surface protrusion and machining fillets are often encountered. The implementation of an electrode-assisted oscillating device has proven effective in improving machining outcomes. To unravel the fundamental reasons behind the optimization enabled by this auxiliary oscillating device, this paper presents fluid simulation research, providing a quantitative comparison of the differences in machining gap flow field characteristics and debris motion behaviors under conditions with and without the assistance of the oscillating device. Firstly, this paper briefly describes the characteristics of C_f-ZrB₂-SiC discharge products and flow field deficiencies during conventional machining and introduces the working principle of electrode-assisted oscillation devices to establish the background and objectives of the simulation study. Subsequently, this research established simulation models for both conventional machining and oscillating machining based on actual processing conditions. CFD numerical simulations were conducted to compare flow field differences between conditions with and without auxiliary machining devices. The results demonstrate that, compared to conventional machining, electrode oscillation not only increases the maximum velocity of the working fluid by nearly 32% but also provides a larger debris accommodation space, effectively preventing secondary discharge. Regarding debris agglomeration, oscillating machining resolves the low-velocity zone issues present in conventional modes, increasing debris velocity from 0 mm/s to 7.5 mm/s and ensuring continuous debris motion. Furthermore, the DPM was used to analyze particle distribution and motion velocities, confirming that vortex effects form within the hole under oscillating conditions. These vortices effectively draw bottom debris outward, preventing local accumulation. Finally, from the perspective of debris distribution, the formation mechanisms of micro-hole morphology and the tool electrode wear patterns were explained. Full article

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25 pages, 11036 KiB

Open AccessArticle

Fatigue Performance Analysis of Weathering Steel Bridge Decks Under Residual Stress Conditions

by Wenye Tian, Ran Li, Tao Lan, Ruixiang Gao, Maobei Li and Qinyuan Liu

Materials 2025, 18(17), 3943; https://doi.org/10.3390/ma18173943 - 22 Aug 2025

Abstract

The growing use of weathering steel in bridge engineering has highlighted the increasing impact of fatigue damage caused by the combined effects of welding residual stress and vehicular loading. This study investigates the fatigue performance of Q500qENH weathering steel bridge decks by proposing [...] Read more.

The growing use of weathering steel in bridge engineering has highlighted the increasing impact of fatigue damage caused by the combined effects of welding residual stress and vehicular loading. This study investigates the fatigue performance of Q500qENH weathering steel bridge decks by proposing a coupled analysis method for residual stress and fatigue crack growth, utilizing collaborative simulations with Abaqus 2023 and Franc3D 7.0. An interaction model integrating welding-induced residual stress fields and dynamic vehicular loads is developed to systematically examine crack propagation patterns in critical regions, including the weld toes of the top plate and the weld seams of the U-ribs. The results indicate that the crack propagation rate at the top plate weld toe exhibits the most rapid progression, reaching the critical dimension (two-thirds of plate thickness) at 6.98 million cycles, establishing this location as the most vulnerable failure point. Residual stresses significantly amplify the stress amplitude under tension–compression cyclic loading, with life degradation effects showing 48.9% greater severity compared to pure tensile stress conditions. Furthermore, parametric analysis demonstrates that increasing the top plate thickness to 16 mm effectively retards crack propagation, while wheel load pressures exceeding 1.0 MPa induce nonlinear acceleration of life deterioration. Based on these findings, engineering countermeasures including welding defect control, optimized top plate thickness (≥16 mm), and wheel load pressure limitation (≤1.0 MPa) are proposed, providing theoretical support for fatigue-resistant design and maintenance of weathering steel bridge decks. Full article

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

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18 pages, 4761 KiB

Open AccessArticle

Influence of Acidic Storage and Simulated Toothbrushing on the Translucency and Color Stability of 3D-Printed Resins for Prosthodontic Applications

by Sarah M. Alnafaiy, Nawaf Labban, Alhanoof Saleh Aldegheishem, Saleh Alhijji, Refal Saad Albaijan, Saad Saleh AlResayes, Rafa Abdulrahman Alsultan, Abeer Mohammed Alrossais and Rahaf Farhan Alanazi

Materials 2025, 18(17), 3942; https://doi.org/10.3390/ma18173942 - 22 Aug 2025

Abstract

This study aimed to assess the effect of acidic storage and simulated brushing on the translucency and color stability of 3D-printed resins for prosthodontic applications. Three 3D printed resin materials—Ceramic Crown (CC), OnX (ONX), and Tough 2 (T2)—were compared with a CAD/CAM milled [...] Read more.

This study aimed to assess the effect of acidic storage and simulated brushing on the translucency and color stability of 3D-printed resins for prosthodontic applications. Three 3D printed resin materials—Ceramic Crown (CC), OnX (ONX), and Tough 2 (T2)—were compared with a CAD/CAM milled nano-ceramic resin material (Lava Ultimate, LU). Twelve specimens were fabricated from each material and were allocated into two groups based on the storage medium (water or citric acid), followed by simulated tooth brushing for 3650 cycles. The specimens’ translucency (TP) and color stability (ΔE) were determined using a spectrophotometer. The data was compared using ANOVA, independent student t-tests, and a post hoc Tukey test (p < 0.05). Multiple comparisons of mean differences in TP revealed significant differences between the tested materials (p < 0.001), except for groups CC and ONX. Irrespective of the groups, all materials showed decreased TP values after simulated tooth brushing. Regarding color stability, CC (0.66 ± 0.42) and T2 (1.40 ± 0.34) in acid demonstrated the least and greatest color changes, respectively. The ΔE did not vary between the materials or between the storage media (p > 0.05). Except for T2 and LU in water, the other materials showed ΔE values below the perceptibility threshold of 1.2. The material type and storage media affected the translucency of the tested materials. However, regardless of the material type and storage media, there was no discernible impact on the color change of the tested materials. Full article

(This article belongs to the Section Biomaterials)

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23 pages, 621 KiB

Open AccessArticle

Biochar as a Sustainable Component of Low-Emission Building Materials

by Iwona Ryłko, Robert Zarzycki, Łukasz Bobak, Paweł Telega, Agnieszka Didyk-Mucha and Andrzej Białowiec

Materials 2025, 18(17), 3941; https://doi.org/10.3390/ma18173941 - 22 Aug 2025

Abstract

Biochar (BC), derived from wood biomass through pyrolysis, exhibits properties that make it a promising additive in mortars for sustainable construction. This study investigated the influence of biochar produced at three pyrolysis temperatures (450 °C, 550 °C, and 700 °C) on the performance [...] Read more.

Biochar (BC), derived from wood biomass through pyrolysis, exhibits properties that make it a promising additive in mortars for sustainable construction. This study investigated the influence of biochar produced at three pyrolysis temperatures (450 °C, 550 °C, and 700 °C) on the performance of cementitious adhesive mortars. The evaluation encompassed physicochemical characterization, mechanical and adhesive strength, volatile organic compound (VOC) emissions, leachability of contaminants, and a life-cycle assessment (LCA). The results demonstrate that biochar obtained at 700 °C has the highest carbon content, an alkaline pH, and increased porosity. In contrast, biochar produced at 450 °C exhibits better sorption capacity and a higher concentration of functional groups. Incorporating 1–5% BC (produced at any temperature) improves mortar performance; however, higher doses negatively affect adhesion to expanded polystyrene board (EPS) and concrete. Emissions of VOCs and leachable metals largely remained within environmental threshold values, with only isolated instances of exceedance. The LCA revealed that substituting mineral fillers with biochar could reduce the carbon footprint by up to 35% compared to the reference formulation. These findings confirm biochar’s potential as a safe and environmentally beneficial component in low-emission construction materials, aligning with the principles of the circular economy and climate-neutral goals. Full article

(This article belongs to the Special Issue Modern Wood-Based Materials for Sustainable Building)

13 pages, 2256 KiB

Open AccessArticle

The Influence of the Ar/N₂ Ratio During Reactive Magnetron Sputtering of TiN Electrodes on the Resistive Switching Behavior of MIM Devices

by Piotr Jeżak, Aleksandra Seweryn, Marcin Klepka and Robert Mroczyński

Materials 2025, 18(17), 3940; https://doi.org/10.3390/ma18173940 - 22 Aug 2025

Abstract

Resistive switching (RS) phenomena are nowadays one of the most studied topics in the area of microelectronics. It can be observed in Metal–Insulator–Metal (MIM) structures that are the basis of resistive switching random-access memories (RRAMs). In the case of commercial use of RRAMs, [...] Read more.

Resistive switching (RS) phenomena are nowadays one of the most studied topics in the area of microelectronics. It can be observed in Metal–Insulator–Metal (MIM) structures that are the basis of resistive switching random-access memories (RRAMs). In the case of commercial use of RRAMs, it is beneficial that the applied materials would have to be compatible with Complementary Metal-Oxide-Semiconductor (CMOS) technology. Fabricating methods of these materials can determine their stoichiometry and structural composition, which can have a detrimental impact on the electrical performance of manufactured devices. In this study, we present the influence of the Ar/N₂ ratio during reactive magnetron sputtering of titanium nitride (TiN) electrodes on the resistive switching behavior of MIM devices. We used silicon oxide (SiOx) as a dielectric layer, which was characterized by the same properties in all fabricated MIM structures. The composition of TiN thin layers was controlled by tuning the Ar/N₂ ratio during the deposition process. The fabricated conductive materials were characterized in terms of chemical and structural properties employing X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis. Structural characterization revealed that increasing the Ar content during the reactive sputtering process affects the crystallite size of the deposited TiN layer. The resulting crystallite sizes ranged from 8 Å to 757.4 Å. The I-V measurements of fabricated devices revealed that tuning the Ar/N₂ ratio during the deposition of TiN electrodes affects the RS behavior. Our work shows the importance of controlling the stoichiometry and structural parameters of electrodes on resistive switching phenomena. Full article

(This article belongs to the Special Issue Advances in Electronic Films: Preparation, Characterization, and Applications)

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28 pages, 19413 KiB

Open AccessArticle

Preparation of Ni-P Composite Coatings and Study on the Corrosion Resistance and Antifouling Properties in Low-Temperature Flue Gas Environment

by Changqi Lv, Shengxian Cao, Bo Zhao and Xingdong Yu

Materials 2025, 18(17), 3939; https://doi.org/10.3390/ma18173939 - 22 Aug 2025

Abstract

In industrial production, flue gas heat exchangers are often affected by the low-temperature condensation of industrial flue gas due to the influence of the working environment, resulting in serious ash deposition and corrosion. In order to solve this problem, in this study, we [...] Read more.

In industrial production, flue gas heat exchangers are often affected by the low-temperature condensation of industrial flue gas due to the influence of the working environment, resulting in serious ash deposition and corrosion. In order to solve this problem, in this study, we developed an ash deposition and corrosion monitoring system to compare the ash deposition prevention performance and corrosion resistance of different materials, as well as its influence on the heat transfer performance of different materials in the same environment. The following coatings were selected for the experiment (values in parentheses are the concentrations of the added compounds): ND, Q235, 316L, Ni-Cu (0.4 g/L)-P, Ni-P-SiO₂ (40 g/L), Ni-Cu (0.4 g/L)-P-SiO₂ (20 g/L), Ni-Cu (0.4 g/L)-P-SiO₂ (40 g/L), and Ni-Cu (0.4 g/L)-P-SiO₂ (60 g/L). The results show that the Ni-Cu (0.4 g/L)-P-SiO₂ (40 g/L) coating has excellent corrosion resistance, while the Ni-Cu (0.4 g/L)-P-SiO₂ (60 g/L) coating shows excellent antifouling performance. Through the comparative analysis of polarization curves, impedance spectra, and coupled corrosion experiments, the test materials were ranked as follows based on their corrosion resistance: 316L > Ni-Cu-P-SiO₂ (40 g/L) > Ni-Cu-P-SiO₂ (20 g/L) > Ni-P-SiO₂ > Ni-Cu-P-SiO₂ (60 g/L) > Ni-Cu-P > ND > Q235. It was also demonstrated that the new coated pipes were able to reduce the exhaust temperature below the dew point and maximize the recovery of energy from the exhaust gas. The acid–ash coupling mechanism of the coating in the flue gas environment was further analyzed, and an acid–ash coupling model based on Cu and SiO₂ is proposed. This model analyzes the effect of the coating under the acid–ash coupling mechanism. Using coated tubes in heat exchangers helps to recover waste heat from coal-fired boilers, enhance heat exchange efficiency, extend the service life of heat exchangers, and reduce costs. Full article

(This article belongs to the Section Corrosion)

16 pages, 2270 KiB

Open AccessArticle

A Novel Test Set-Up for Direct Evaluation of Impact and Energy Absorption for Lattices

by Mohammad Reza Vaziri Sereshk, Kamil L. Kwiecien, Akib T. Lodhi and Mohammad Mahjoob

Materials 2025, 18(17), 3938; https://doi.org/10.3390/ma18173938 - 22 Aug 2025

Abstract

The application of lattices as protective materials/structures is rapidly increasing. This requires improving impact absorption capabilities to protect goods in packaging and prevent human injuries in protective devices. This study aims to improve the accuracy of impact and energy absorption measurements for lattices, [...] Read more.

The application of lattices as protective materials/structures is rapidly increasing. This requires improving impact absorption capabilities to protect goods in packaging and prevent human injuries in protective devices. This study aims to improve the accuracy of impact and energy absorption measurements for lattices, addressing the limitations of current methods such as energy-impact diagrams and instrumented drop-impact testers. A novel test setup is introduced by utilizing a modified Charpy test machine equipped with appropriate instrumentation to directly measure both energy and acceleration. Other modifications include adjustments to the machine components and the introduction of a new sandwich configuration for the test specimen, ensuring compatibility with the machine’s geometry and the test objectives. The attractiveness of the proposed test setup lies in its simplicity and efficiency. Unlike drop-impact test machines—which require complex, time-consuming, and error-prone data integration and derivation—the proposed method eliminates the need for postprocessing, as both energy and impact are recorded directly and instantaneously by the machine. The advantage over existing setups becomes particularly evident when considering that, in the presence of noise and high-frequency fluctuations—characteristic of sensor data from impact events—errors in numerical operations can range from 30% to over 100%. The functionality of the proposed test setup is evaluated through a series of experiments, and the results are compared with those obtained from existing methods. Our findings demonstrate the effectiveness of the new setup in providing accurate and direct measures of absorption parameters, offering a significant improvement over the traditional approaches. Full article

(This article belongs to the Special Issue Advances in Porous Lightweight Materials and Lattice Structures)

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51 pages, 9429 KiB

Open AccessReview

Research Progress of Persistent Luminescence Nanoparticles in Biological Detection Imaging and Medical Treatment

by Kunqiang Deng, Kunfeng Chen, Sai Huang, Jinkai Li and Zongming Liu

Materials 2025, 18(17), 3937; https://doi.org/10.3390/ma18173937 - 22 Aug 2025

Abstract

Persistent luminescence nanoparticles (PLNPs) represent a unique class of optical materials. They possess the ability to absorb and store energy from external excitation sources and emit light persistently once excitation terminates. Because of this distinctive property, PLNPs have attracted considerable attention in various [...] Read more.

Persistent luminescence nanoparticles (PLNPs) represent a unique class of optical materials. They possess the ability to absorb and store energy from external excitation sources and emit light persistently once excitation terminates. Because of this distinctive property, PLNPs have attracted considerable attention in various areas. Especially in recent years, PLNPs have revealed marked benefits and extensive application potential in fields such as biological detection, imaging, targeted delivery, as well as integrated diagnosis and treatment. Not only do they potently attenuate autofluorescence interference arising from biological tissues, but they also demonstrate superior signal-to-noise ratio and sensitivity in in vivo imaging scenarios. Therefore, regarding the current research, this paper firstly introduces the classification, synthesis methods, and luminescence mechanism of the materials. Subsequently, the research progress of PLNPs in biological detection and imaging and medical treatment in recent years is reviewed. The challenges faced by materials in biomedical applications and the outlook of future development trends are further discussed, which delivers an innovative thought pattern for developing and designing new PLNPs to cater to more practical requirements. Full article

(This article belongs to the Special Issue Electrochemical and Luminescent Sensor Materials for Biological and Biomedical Applications)

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33 pages, 12503 KiB

Open AccessArticle

Molecular Adhesion Between Asphalt and Glass Fiber-Reinforced Composites from Recycled Wind Turbine Blades in Dry and Hydrated Conditions

by Jiehao Feng, Shuliang Wang, Fan He, Chuanhai Wu, Zhixiang Wang, Fen Du, Dryver Huston, Mandar Dewoolkar and Ting Tan

Materials 2025, 18(17), 3936; https://doi.org/10.3390/ma18173936 - 22 Aug 2025

Abstract

A large number of wind turbine blades will be retired in the near future. Glass fiber-reinforced composites from retired blades, due to their extraordinary strength, toughness, and durability, are promising aggregate candidates in asphalt mixtures. This work studied the interfacial behavior between asphalt [...] Read more.

A large number of wind turbine blades will be retired in the near future. Glass fiber-reinforced composites from retired blades, due to their extraordinary strength, toughness, and durability, are promising aggregate candidates in asphalt mixtures. This work studied the interfacial behavior between asphalt and glass fiber-reinforced composites through combined molecular modeling and experimental approaches. Predictions from molecular modeling were first verified through experimental findings using particle probe scanning force microscopy. Then, molecular simulations were conducted to examine the chemical adhesion between binders and aggregates made from minerals and wind turbine blades. The results showed that epoxy–binder adhesion was higher than calcite–binder and silica–binder adhesion but lower than alumina–binder adhesion, denoting that the glass fiber composite aggregates were comparable in chemical adhesion to mineral aggregates. The adhesion was primarily due to van der Waals forces (>80%). Furthermore, the dependence of epoxy–asphalt adhesion on loading rates was examined, during which the high-speed, transitions, and low-speed regions were identified. The impact of water on interfacial behavior was illustrated by examining how water molecules infiltrated interfaces between aggregates and binders at different speeds. The results showed that interfacial adhesion in a hydrated state at low speeds was 20–40% lower than that in a dry state, whereas at high speeds, interfacial adhesion in a hydrated state was 5–15% higher than that in dry conditions. These results could provide essential guidance for the application of retired wind turbine blades as asphalt aggregates. Full article

(This article belongs to the Section Advanced Composites)

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