Materials

18 pages, 1479 KiB

Open AccessArticle

Structural Mechanics Calculations of SiC/Mo-Re Composites with Improved High Temperature Creep Properties

by Ke Li, Egor Kashkarov, Hailiang Ma, Ping Fan, Qiaoli Zhang, Andrey Lider and Daqing Yuan

Materials 2025, 18(15), 3459; https://doi.org/10.3390/ma18153459 - 23 Jul 2025

In the present work, we design a laminated composite composed of molybdenum–rhenium alloy and silicon carbide ceramics for use in space reactors as a candidate structural material with neutron spectral shift properties. The influence of the internal microstructure on the mechanical properties is [...] Read more.

In the present work, we design a laminated composite composed of molybdenum–rhenium alloy and silicon carbide ceramics for use in space reactors as a candidate structural material with neutron spectral shift properties. The influence of the internal microstructure on the mechanical properties is investigated by finite element simulation based on scale separation. The results of the study showed that the incorporation of gradient transition layers between the metallic and ceramic phases effectively mitigates thermally induced local stresses arising from mismatches in coefficients of thermal expansion. By optimizing the composition of the gradient transition layers, the stress distribution within the composite under operating conditions has been adjusted. As a result, the stress experienced by the alloy phase is significantly reduced, potentially extending the high-temperature creep rupture life. Full article

(This article belongs to the Section Advanced Composites)

23 pages, 6601 KiB

Open AccessArticle

Effect of Hemp Shive Granulometry on the Thermal Conductivity of Hemp–Lime Composites

by Wojciech Piątkiewicz, Piotr Narloch, Zuzanna Wólczyńska and Joanna Mańczak

Materials 2025, 18(15), 3458; https://doi.org/10.3390/ma18153458 - 23 Jul 2025

Abstract

This study investigates the effect of hemp shive granulometry on the thermal conductivity and microstructure of hemp–lime composites. Three distinct particle size fractions—fine, medium, and coarse—were characterized using high-resolution image analysis to determine geometric parameters such as Feret diameters, circularity, and elongation. Composite [...] Read more.

This study investigates the effect of hemp shive granulometry on the thermal conductivity and microstructure of hemp–lime composites. Three distinct particle size fractions—fine, medium, and coarse—were characterized using high-resolution image analysis to determine geometric parameters such as Feret diameters, circularity, and elongation. Composite mixtures with varying binder-to-shive and water-to-shive ratios were prepared and compacted at a consistent level to isolate the influence of aggregate granulometry on thermal performance. Results demonstrate a clear inverse relationship between particle size and thermal conductivity, with coarse fractions reducing thermal conductivity by up to 7.6% compared to fine fractions. Composite density was also affected, decreasing with increasing particle size, confirming the impact of granulometry on pore structure and packing density. However, binder content exhibited the most significant effect on thermal conductivity, with a 20% increase observed for higher binder-to-shive ratios irrespective of shive size. The study further establishes that a 15 g sample size (~2400 particles) provides sufficient statistical accuracy for granulometric characterization using image analysis. These findings provide critical insights for optimizing hemp–lime composites for enhanced thermal insulation performance, supporting sustainable construction practices by informing material formulation and processing parameters. Full article

(This article belongs to the Special Issue Sustainable Construction and Building Materials: Microstructure, Mechanical Performance, and Long-Term Durability)

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13 pages, 3360 KiB

Open AccessArticle

Effect of Edge-Oxidized Graphene Oxide (EOGO) on Fly Ash Geopolymer

by Hoyoung Lee, Junwoo Shin, Byoung Hooi Cho and Boo Hyun Nam

Materials 2025, 18(15), 3457; https://doi.org/10.3390/ma18153457 (registering DOI) - 23 Jul 2025

Abstract

In this study, edge-oxidized graphene oxide (EOGO) was used as an additive in fly ash (FA) geopolymer paste. The effect of EOGO on the properties of the fly ash geopolymer was investigated. EOGO was added to the FA geopolymer at four different percentages [...] Read more.

In this study, edge-oxidized graphene oxide (EOGO) was used as an additive in fly ash (FA) geopolymer paste. The effect of EOGO on the properties of the fly ash geopolymer was investigated. EOGO was added to the FA geopolymer at four different percentages (0%, 0.1%, 0.5% and 1%), and the mixture was cured under two different conditions: room curing (~20 °C) and heat curing (~60 °C). To characterize the FA-EOGO geopolymer, multiple laboratory tests were employed, including compressive strength, Free-Free Resonance Column (FFRC), density, water absorption, and setting tests. The FFRC test was used to evaluate the stiffness at small strain (Young’s modulus) via the resonance of the specimen. The mechanical test results showed that the strength and elastic modulus were high during heat curing, and the highest compressive strength and elastic modulus were achieved at 0.1% EOGO. In the physical test, 0.1% EOGO had the highest density and the lowest porosity and water absorption. As a result of the setting time test, as the EOGO content increased, the setting time was shortened. It is concluded that the optimum proportion of EOGO is 0.1% in FA geopolymer paste. Full article

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

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25 pages, 5190 KiB

Open AccessArticle

Comparative Evaluation of the Effectiveness and Efficiency of Computational Methods in the Detection of Asbestos Cement in Hyperspectral Images

by Gabriel Elías Chanchí-Golondrino, Manuel Saba and Manuel Alejandro Ospina-Alarcón

Materials 2025, 18(15), 3456; https://doi.org/10.3390/ma18153456 - 23 Jul 2025

Abstract

Among the existing challenges in the field of hyperspectral imaging, the need to optimize memory usage and computational capacity in material detection methods stands out, given the vast amount of data associated with the hundreds of reflectance bands. In line with this, this [...] Read more.

Among the existing challenges in the field of hyperspectral imaging, the need to optimize memory usage and computational capacity in material detection methods stands out, given the vast amount of data associated with the hundreds of reflectance bands. In line with this, this article proposes a comparative study on the effectiveness and efficiency of five computational methods for detecting composite material asbestos cement (AC) in hyperspectral images: correlation, spectral differential similarity (SDS), Fourier phase similarity (FPS), area under the curve (AUC), and decision trees (DT). The novelty lies in the comparison between the first four methods, which represent the spectral proximity method and a machine learning method, such as DT. Furthermore, SDS and FPS are novel methods proposed in the present document. Given the accuracy that detection methods based on supervised learning have demonstrated in material identification, the results obtained from the DT model were compared with the percentage of AC detected in a hyperspectral image of the Manga neighborhood in the city of Cartagena by the other four methods. Similarly, in terms of computational efficiency, a 20 × 20 pixel region with 380 bands was selected for the execution of multiple repetitions of each of the five computational methods considered, in order to obtain the average processing time of each method and the relative efficiency of the methods with respect to the method with the best effectiveness. The decision tree (DT) model achieved the highest classification accuracy at 99.4%, identifying 11.44% of asbestos cement (AC) pixels in the reference image. However, the correlation method, while detecting a lower percentage of AC pixels (9.72%), showed the most accurate visual performance and had no spectral overlap, with a 1.4% separation between AC and non-AC pixels. The SDS method was the most computationally efficient, running 23.85 times faster than the DT model. The proposed methods and results can be applied to other hyperspectral imaging tasks involving material identification in urban environments, especially when balancing accuracy and computational efficiency is essential. Full article

(This article belongs to the Special Issue Experimental Testing, Manufacturing and Numerical Modelling of Composite and Sandwich Structures (Second Edition))

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24 pages, 5021 KiB

Open AccessArticle

Enhanced Mechanical and Electromagnetic Shielding Properties of Mg Matrix Layered Composites Reinforced with Hybrid Graphene Nanosheet (GNS)–Carbon Nanotube (CNT) Networks

by Hailong Shi, Jiancheng Zhao, Zhenming Sun, Xiaojun Wang, Xiaoshi Hu, Xuejian Li, Chao Xu, Weimin Gan and Chao Ding

Materials 2025, 18(15), 3455; https://doi.org/10.3390/ma18153455 - 23 Jul 2025

Abstract

The development of lightweight composites with superior mechanical properties and electromagnetic interference (EMI) shielding performance is essential for various structural and functional applications. This study investigates the effect of hybrid nanocarbon (graphene nanosheet (GNS) and carbon nanotube (CNT)) reinforcements on the properties of [...] Read more.

The development of lightweight composites with superior mechanical properties and electromagnetic interference (EMI) shielding performance is essential for various structural and functional applications. This study investigates the effect of hybrid nanocarbon (graphene nanosheet (GNS) and carbon nanotube (CNT)) reinforcements on the properties of magnesium (Mg) matrix composites. Specifically, the GNS-CNT hybrid, which forms a three-dimensional interconnected network structure, was analyzed and compared to composites reinforced with only GNSs or CNTs. The objective was to determine the benefits of hybrid reinforcements on the mechanical strength and EMI shielding capability of the composites. The results indicated that the GNS-CNT/Mg composite, at a nanocarbon content of 0.5 wt.% and a GNS-CNT ratio of 1:2, achieved optimal performance, with a 55% increase in tensile strength and an EMI shielding effectiveness of 70 dB. The observed enhancements can be attributed to several key mechanisms: effective load transfer, which promotes tensile twinning, along with improved impedance matching and multiple internal reflections within the GNS-CNT network, which enhance absorption loss. These significant improvements position the composite as a promising candidate for advanced applications requiring high strength, toughness, and efficient electromagnetic shielding, providing valuable insights into the design of high-performance lightweight materials. Full article

(This article belongs to the Section Advanced Composites)

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14 pages, 2336 KiB

Open AccessArticle

Analog Resistive Switching Phenomena in Titanium Oxide Thin-Film Memristive Devices

by Karimul Islam, Rezwana Sultana and Robert Mroczyński

Materials 2025, 18(15), 3454; https://doi.org/10.3390/ma18153454 - 23 Jul 2025

Abstract

Memristors with resistive switching capabilities are vital for information storage and brain-inspired computing, making them a key focus in current research. This study demonstrates non-volatile analog resistive switching behavior in Al/TiO_x/TiN/Si(n⁺⁺)/Al memristive devices. Analog resistive switching offers gradual, controllable [...] Read more.

Memristors with resistive switching capabilities are vital for information storage and brain-inspired computing, making them a key focus in current research. This study demonstrates non-volatile analog resistive switching behavior in Al/TiO_x/TiN/Si(n⁺⁺)/Al memristive devices. Analog resistive switching offers gradual, controllable conductance changes, which are essential for mimicking brain-like synaptic behavior, unlike digital/abrupt switching. The amorphous titanium oxide (TiO_x) active layer was deposited using the pulsed-DC reactive magnetron sputtering technique. The impact of increasing the oxide thickness on the electrical performance of the memristors was investigated. Electrical characterizations revealed stable, forming-free analog resistive switching, achieving endurance beyond 300 DC cycles. The charge conduction mechanisms underlying the current–voltage (I–V) characteristics are analyzed in detail, revealing the presence of ohmic behavior, Schottky emission, and space-charge-limited conduction (SCLC). Experimental results indicate that increasing the TiO_x film thickness from 31 to 44 nm leads to a notable change in the current conduction mechanism. The results confirm that the memristors have good stability (>1500 s) and are capable of exhibiting excellent long-term potentiation (LTP) and long-term depression (LTD) properties. The analog switching driven by oxygen vacancy-induced barrier modulation in the TiO_x/TiN interface is explained in detail, supported by a proposed model. The remarkable switching characteristics exhibited by the TiO_x-based memristive devices make them highly suitable for artificial synapse applications in neuromorphic computing systems. Full article

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

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18 pages, 4169 KiB

Open AccessArticle

Sustainable Thermoelectric Composites: A Study of Bi₂Te₃-Filled Biobased Resin

by Luca Ferretti, Pietro Russo, Jessica Passaro, Francesca Nanni, Saverio D’Ascoli, Francesco Fabbrocino and Mario Bragaglia

Materials 2025, 18(15), 3453; https://doi.org/10.3390/ma18153453 - 23 Jul 2025

Abstract

In this work, bio-based thermoelectric composites were developed using acrylated epoxidized soybean oil (AESO) as the polymer matrix and bismuth telluride (Bi₂Te₃) as the thermoelectric filler. The materials were formulated for both UV-curing and thermal-curing processes, with a focus [...] Read more.

In this work, bio-based thermoelectric composites were developed using acrylated epoxidized soybean oil (AESO) as the polymer matrix and bismuth telluride (Bi₂Te₃) as the thermoelectric filler. The materials were formulated for both UV-curing and thermal-curing processes, with a focus on Digital Light Processing (DLP) 3D printing. Although UV curing proved ineffective at high filler concentrations due to the light opacity of Bi₂Te₃, thermal curing enabled the fabrication of stable, homogeneously dispersed composites. The samples were thoroughly characterized through rheology, FTIR, TGA, XRD, SEM, and density measurements. Thermoelectric performance was assessed under a 70 °C temperature gradient, with Seebeck coefficients reaching up to 51 µV/K. Accelerated chemical degradation studies in basic media confirmed the degradability of the matrix. The results demonstrate the feasibility of combining additive manufacturing with sustainable materials for low-power thermoelectric energy harvesting applications. Full article

(This article belongs to the Special Issue Polymer Composites: Microstructural, Thermal and Mechanical Properties (Third Edition))

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20 pages, 6019 KiB

Open AccessArticle

Effect of Hole Diameter on Failure Load and Deformation Modes in Axially Compressed CFRP Laminates

by Pawel Wysmulski

Materials 2025, 18(15), 3452; https://doi.org/10.3390/ma18153452 - 23 Jul 2025

Abstract

This study presents a detailed analysis of the influence of hole presence and size on the behavior of CFRP composite plates subjected to axial compression. The plates were manufactured by an autoclave method from eight-ply laminate in a symmetrical fiber arrangement [45°/−45°/90°/0°₂ [...] Read more.

This study presents a detailed analysis of the influence of hole presence and size on the behavior of CFRP composite plates subjected to axial compression. The plates were manufactured by an autoclave method from eight-ply laminate in a symmetrical fiber arrangement [45°/−45°/90°/0°₂/90°/−45°/45°]. Four central hole plates of 0 mm (reference), 2 mm, 4 mm, and 8 mm in diameter were analyzed. Tests were conducted using a Cometech universal testing machine in combination with the ARAMIS digital image correlation (DIC) system, enabling the non-contact measurement of real-time displacements and local deformations in the region of interest. The novel feature of this work was its dual use of independent measurement methods—machine-based and DIC-based—allowing for the assessment of boundary condition effects and grip slippage on failure load accuracy. The experiments were carried out until complete structural failure, enabling a post-critical analysis of material behavior and failure modes for different geometric configurations. The study investigated load–deflection and load–shortening curves, failure mechanisms, and ultimate loads. The results showed that the presence of a hole leads to localized deformation, a change in the failure mode, and a nonlinear reduction in load-carrying capacity—by approximately 30% for the largest hole. These findings provide complementary data for the design of thin-walled composite components with technological openings and serve as a robust reference for numerical model validation. Full article

(This article belongs to the Section Advanced Composites)

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17 pages, 7033 KiB

Open AccessArticle

A Study on the Low-Intensity Cracking Resistance of Drainage Asphalt Mixtures by Graphene/Rubber Powder Compound Modified Asphalt

by Jingcheng Chen, Yongqiang Cheng, Ke Liang, Xiaojian Cao, Yanchao Wang and Qiangru Shen

Materials 2025, 18(15), 3451; https://doi.org/10.3390/ma18153451 - 23 Jul 2025

Abstract

In order to investigate the influence of graphene/rubber powder compound modified asphalt on the low-temperature cracking resistance of drainage asphalt mixtures, graphene/rubber powder compound modified asphalt mixtures were prepared using graphene/rubber powder compound modified asphalt for drainage asphalt mixtures, and compared with SBS-modified [...] Read more.

In order to investigate the influence of graphene/rubber powder compound modified asphalt on the low-temperature cracking resistance of drainage asphalt mixtures, graphene/rubber powder compound modified asphalt mixtures were prepared using graphene/rubber powder compound modified asphalt for drainage asphalt mixtures, and compared with SBS-modified asphalt and rubber powder-modified asphalt, and the low-temperature cracking resistance of graphene/rubber powder compound modification asphalt mixtures was investigated through the Marshall Stability Test, Semi-circular Bending Test (SCB), and Freeze–Thaw Split Test. Research was carried out. At the same time, a scanning electric microscope (SEM) was adopted to analyze the micro-mechanism of the graphene/rubber powder compound modified asphalt mixtures under the microscopic condition. The findings showed that graphene dispersed the aggregation of rubber powder effectively in the microscopic state and improved the stability of the composite modified asphalt. The addition of graphene improved the fracture energy of rubber powder composite modified asphalt by 15.68% under the condition of −15 °C to 0 °C, which effectively slowed down the decrease of fracture energy; at −15 °C and −10 °C, the largest stresses were improved by 7.50% and 26.71%, respectively, compared to the drainage asphalt mixtures prepared as rubber powder-modified asphalt and SBS-modified asphalt. After a freeze–thaw cycle, the maximum stress decrease of graphene/rubber powder compound modified asphalt was 21.51% and 10.37% at −15 °C and 0 °C, respectively. When compared to rubber powder-modified asphalt, graphene/rubber powder compound modified asphalt significantly improved the low-intensity cracking resistance of drainage asphalt mixtures at low temperatures, slowed down the decrease of the maximum stress, and its low-temperature cracking resistance was more stable. Full article

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

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17 pages, 2754 KiB

Open AccessArticle

The Regulation of Thermodynamic Behavior and Structure of Aluminosilicate Glasses via the Mixed Alkaline Earth Effect

by Lin Yuan, Xurong Teng, Ping Li, Ouyuan Zhang, Fangfang Zhao, Changyuan Tao and Renlong Liu

Materials 2025, 18(15), 3450; https://doi.org/10.3390/ma18153450 - 23 Jul 2025

Abstract

This work systematically altered the molar ratio of CaO and MgO (R = [CaO]/[(CaO + MgO)], mol%) to elucidate the underlying mechanisms driving the observed changes in macroscopic properties. The results indicated that as CaO increasingly replaced MgO, the rise in the content [...] Read more.

This work systematically altered the molar ratio of CaO and MgO (R = [CaO]/[(CaO + MgO)], mol%) to elucidate the underlying mechanisms driving the observed changes in macroscopic properties. The results indicated that as CaO increasingly replaced MgO, the rise in the content of non-bridging oxygen led to the depolymerization of the glass structure. A quantitative analysis of Qⁿ units in the [SiO₄] tetrahedron using ²⁹Si MAS NMR revealed that a non-monotonic variation appeared when the Q⁴ unit reached a minimum at R = 0.7. Meanwhile, the chemical environment of aluminum also varies with the R, and the presence of high-coordinated aluminum species is observed when Ca²⁺ and Mg²⁺ ions coexist. In terms of overall performance, both density and molar volume exhibited a linear trend. However, thermal stability, viscosity, characteristic temperatures (including melting temperature, Littleton softening temperature, working point temperature, and glass transition temperature), and mechanical properties showed deviations from linearity. Additionally, four non-isothermal thermodynamics was employed to quantitatively assess the thermal stability of samples C-0.7 and C-1. The insights gained from this study will aid in the development of advanced glass materials with tailored properties for industrial applications. Full article

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15 pages, 2557 KiB

Open AccessArticle

Use of Phalaris canariensis Extract as CO₂ Corrosion Inhibitor of Brass

by Edgar Salazar-Salazar, Dante Guillermo Gutierrez-Granda, Earvin Galvan, Ana Karen Larios-Galvez, America Maria Ramirez-Arteaga, Roy Lopez-Sesenes, Alfredo Brito-Franco, Jesus Porcayo-Calderon and Jose Gonzalo Gonzalez-Rodriguez

Materials 2025, 18(15), 3449; https://doi.org/10.3390/ma18153449 - 23 Jul 2025

Abstract

In this study, the corrosion inhibition of a Phalaris canariensis extract on brass in a CO₂-saturated 3.5% NaCl solution is evaluated with the aid of potentiodynamic polarization curves and electrochemical impedance spectroscopy tests. The results indicate that the Phalaris canariensis extract [...] Read more.

In this study, the corrosion inhibition of a Phalaris canariensis extract on brass in a CO₂-saturated 3.5% NaCl solution is evaluated with the aid of potentiodynamic polarization curves and electrochemical impedance spectroscopy tests. The results indicate that the Phalaris canariensis extract is an excellent CO₂ corrosion inhibitor with an efficiency that increases with its concentration, reaching its maximum value of 99% with an inhibitor concentration of 100 ppm, decreasing the corrosion current density by more than two orders of magnitude. The addition of the Phalaris canariensis extract increased the pitting potential, decreased the passive current density values, and affected cathodic reactions, behaving as a mixed type of inhibitor. The corrosion process was under charge transfer control, and it was neither affected by the addition of the inhibitor nor by the elapsing time. The main compounds found in the Phalaris canariensis extract included antioxidants such as palmitic and oleic acids. Full article

(This article belongs to the Special Issue Surface Engineering & Coating Technologies for Corrosion and Tribocorrosion Resistance—3rd Edition)

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17 pages, 5746 KiB

Open AccessArticle

The Influence of Hydrogen-Charging Current Density and Temperature on Hydrogen Permeation and Hydrogen Embrittlement Susceptibility of 4130X Steel

by Caijun Xu, Fang Wang and Jiaqing Li

Materials 2025, 18(15), 3448; https://doi.org/10.3390/ma18153448 - 23 Jul 2025

Abstract

Chromium-molybdenum steels are extensively used in manufacturing large-volume seamless hydrogen storage vessels, but they still suffer from the hydrogen embrittlement problem. In this study, electrochemical cathodic hydrogen charging is utilized to investigate the hydrogen embrittlement of 4130X steels, with emphasis on the influence [...] Read more.

Chromium-molybdenum steels are extensively used in manufacturing large-volume seamless hydrogen storage vessels, but they still suffer from the hydrogen embrittlement problem. In this study, electrochemical cathodic hydrogen charging is utilized to investigate the hydrogen embrittlement of 4130X steels, with emphasis on the influence of charging current density and temperature on hydrogen permeation and hydrogen embrittlement susceptibility. The hydrogen penetration rate and hydrogen diffusion coefficient of 4130X steel both increase with an increase in hydrogen-charging current density and temperature. The results demonstrate that the degree of hydrogen-induced degradation in tensile ductility is more marked with increasing hydrogen-charging current density, while the hydrogen embrittlement index exhibits a peak at a temperature of 308 K, in which brittle patterns like quasi-cleavage surfaces and crack formations occur. These findings are crucial for understanding hydrogen-induced embrittlement and determining test temperatures of hydrogen-related engineering material applications. Full article

(This article belongs to the Special Issue Multiscale Characterization and Computational Modeling/Simulation of Metallic Materials)

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20 pages, 3274 KiB

Open AccessArticle

Investigation of the Influence of Process Parameters on the Physicochemical and Functional Properties of Oil-Based Composites

by Anita Zawadzka and Magda Kijania-Kontak

Materials 2025, 18(15), 3447; https://doi.org/10.3390/ma18153447 - 23 Jul 2025

Abstract

The increasing consumption of edible oils has resulted in a parallel rise in waste cooking oil (WCO), a harmful waste stream but one that also represents a promising raw material. In this study, oil-based binders were synthesised from WCO using various reagents: Sulfuric(VI) [...] Read more.

The increasing consumption of edible oils has resulted in a parallel rise in waste cooking oil (WCO), a harmful waste stream but one that also represents a promising raw material. In this study, oil-based binders were synthesised from WCO using various reagents: Sulfuric(VI) acid, hydrobromic acid, acetic acid, salicylic acid, glycolic acid, zinc acetate, ethanol, hydrogen peroxide, and their selected mixtures. The manufacturing process was optimised, and the composites were evaluated for physicochemical and mechanical properties, including compressive strength, bending strength, and water absorption. The best performance was observed for composites catalysed with a mixture of sulfuric(VI) acid and 20% hydrogen peroxide, cured at 240 °C, yielding compressive and bending strengths of 5.20 MPa and 1.34 MPa, respectively. Under modified curing conditions, a compressive strength of 5.70 MPa and a bending strength of 0.75 MPa were obtained. The composite modified with glycolic acid showed the lowest water absorption (3%). These findings demonstrate how catalyst type and curing parameters influence composite structure, porosity, and mechanical behaviour. The study provides new insights into the process–structure–property relationships in oil-based materials and supports the development of environmentally friendly composites from waste feedstocks. Full article

(This article belongs to the Section Advanced Composites)

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15 pages, 2256 KiB

Open AccessArticle

In Vivo Wear Analysis of Leucite-Reinforced Ceramic Inlays/Onlays After 14 Years

by Ragai-Edward Matta, Lara Berger, Oleksandr Sednyev, Dennis Bäuerle, Eva Maier, Werner Adler and Michael Taschner

Materials 2025, 18(15), 3446; https://doi.org/10.3390/ma18153446 - 23 Jul 2025

Abstract

Material wear significantly impacts the clinical success and longevity of dental ceramic restorations. This in vivo study aimed to assess the wear behavior of IPS Empress^® glass-ceramic inlays and onlays over 14 years, considering the influence of different antagonist materials. Fifty-four indirect [...] Read more.

Material wear significantly impacts the clinical success and longevity of dental ceramic restorations. This in vivo study aimed to assess the wear behavior of IPS Empress^® glass-ceramic inlays and onlays over 14 years, considering the influence of different antagonist materials. Fifty-four indirect restorations of 21 patients were available for comprehensive wear analysis, with complete follow-up data for up to 14 years. Three-dimensional measurements relied on digitized epoxy resin models produced immediately post-insertion (baseline) and subsequently at 2, 4, and 14 years. The occlusal region on the baseline model was delineated for comparative analysis. Three-dimensional superimpositions with models from subsequent time points were executed to assess wear in terms of average linear wear and volumetric loss. Statistical analyses were conducted in R (version 4.4.1), employing Mann–Whitney U tests (material comparisons) and Wilcoxon signed rank tests (time point comparisons), with a significance threshold of p ≤ 0.05. During the entire study period, an increase in wear was observed at each assessment interval, gradually stabilizing over time. Significant differences in substance loss were found between the follow-up time points, both for mean (−0.536 ± 0.249 mm after 14a) and integrated distance (−18,935 ± 11,711 mm³ after 14a). In addition, significantly higher wear was observed after 14 years with gold as antagonist compared to other materials (p ≤ 0.03). The wear behavior of IPS Empress^® ceramics demonstrates clinically acceptable long-term outcomes, with abrasion characteristics exhibiting stabilization over time. Full article

(This article belongs to the Special Issue Advanced Dental Materials: From Design to Application, Second Volume)

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15 pages, 6193 KiB

Open AccessArticle

Microscopy Study of (Ti,Nb)(C,N) Precipitation in Microalloyed Steels Under Continuous Casting Conditions

by Fangyong Xu, Daoyao Liu, Wei Wang, Brian G. Thomas, Tianxu Wu, Kun Xu and Zhan Zhang

Materials 2025, 18(15), 3445; https://doi.org/10.3390/ma18153445 - 23 Jul 2025

Abstract

The continuous casting of Ti-Nb microalloyed steel was simulated with high temperature confocal laser scanning microscopy (HTCLSM). Evolution of the sample surface morphology was observed in-situ, during cooling conditions chosen to represent different locations in a cast slab. Calculations with a thermodynamics model [...] Read more.

The continuous casting of Ti-Nb microalloyed steel was simulated with high temperature confocal laser scanning microscopy (HTCLSM). Evolution of the sample surface morphology was observed in-situ, during cooling conditions chosen to represent different locations in a cast slab. Calculations with a thermodynamics model of carbonitride precipitate formation agreed with the transmission electron microscopy (TEM) analysis that fine reliefs observed on the sample surface were actually caused by interior precipitation of (Ti,Nb)(C,N). Precipitation and the resulting reliefs changed with location beneath the slab surface, simulated casting speed, and steel composition. With the same casting speed and steel composition, reliefs in the simulated slab surface sample appeared earlier and were larger than in the slab center. With increased casting speed, reliefs were observed later and decreased in size. With increased titanium or niobium content, reliefs appeared earlier and increased in number. TEM measurement showed that the precipitate diameters were mainly smaller than 4 nm, with a few between 4 and 8 nm. The property of surface reliefs observed via HTCLSM correlated qualitatively with the number and size of internal precipitates measured with TEM, showing this to be an effective tool for indirectly characterizing nanoscale secondary phase precipitation inside the sample. Full article

(This article belongs to the Section Metals and Alloys)

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18 pages, 5469 KiB

Open AccessArticle

Site Application of Thermally Conductive Concrete Pavement: A Comparison of Its Thermal Effectiveness with Normal Concrete Pavement

by Joo-Young Kim and Jae-Suk Ryou

Materials 2025, 18(15), 3444; https://doi.org/10.3390/ma18153444 - 23 Jul 2025

Abstract

In this study, the thermal effectiveness of thermally conductive concrete pavements (TCPs) using silicon carbide (SiC) as a fine aggregate replacement was investigated, compared with that of ordinary Portland cement pavements (OPCPs). The most important purpose of this study is to improve the [...] Read more.

In this study, the thermal effectiveness of thermally conductive concrete pavements (TCPs) using silicon carbide (SiC) as a fine aggregate replacement was investigated, compared with that of ordinary Portland cement pavements (OPCPs). The most important purpose of this study is to improve the thermal performance of concrete pavement. Additionally, this study utilized improved thermal properties to enhance the efficiency of pavement heating to prevent icing and snow stacking. Both mixtures met the Korean standards for air content (4.5–6%) and slump (80–150 mm), demonstrating adequate workability. TCP exhibited a higher mechanical performance, with average compressive and flexural strengths of 42.88 MPa and 7.35 MPa, respectively, exceeding the required targets of a 30 MPa compressive strength and a 4.5 MPa flexural strength. The improved strength was mainly attributed to the filler effect and partly due to the van der Waals interactions of the SiC particles. Thermal conductivity tests showed a significant improvement in the TCP (3.20 W/mK), which was approximately twice that of OPCP (1.59 W/mK), indicating an enhanced heat transfer efficiency. In winter field tests, TCP effectively maintained high surface temperatures, overcoming heat loss and outperforming the OPCP. In the site experiment, thermal efficiency was clearly shown in the temperature at the center of the TCP, which was 3.5 °C higher than at the center of the OPCP at the coldest time. These improvements suggest that SiC-reinforced concrete pavements can be practically utilized for effective snow removal and ice mitigation in road systems. Full article

(This article belongs to the Special Issue State-of-the-Art Construction Materials and Technologies for Structural Health Monitoring of Infrastructures)

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19 pages, 3113 KiB

Open AccessArticle

Durable Superhydrophobic Composite Coating Based on Hydrangea-like SiO₂ Nanoparticles with Excellent Performance in Anticorrosion, Drag Reduction, and Antifouling

by Yuhao Xue, Yamei Zhao, Xiaoqi Gu, Mengdan Huo, Kunde Yang, Mingyu Liu, Sixian Fan and Maoyong Zhi

Materials 2025, 18(15), 3443; https://doi.org/10.3390/ma18153443 - 23 Jul 2025

Abstract

Superhydrophobic coatings possess distinct wettability characteristics and hold significant potential in metal corrosion protection and underwater drag reduction. However, their practical application is often hindered by poor durability arising from the fragility of their micro/nanostructured surface roughness. In this study, a durable superhydrophobic [...] Read more.

Superhydrophobic coatings possess distinct wettability characteristics and hold significant potential in metal corrosion protection and underwater drag reduction. However, their practical application is often hindered by poor durability arising from the fragility of their micro/nanostructured surface roughness. In this study, a durable superhydrophobic coating featuring a hierarchical, hydrangea-like micro/nanostructure was successfully fabricated on an aluminum alloy substrate via a simple one-step cold-spraying technique. The coating consisted of hydrangea-shaped SiO₂ nanoparticles modified with 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (PFDT) to produce multiscale roughness, while epoxy resin (EP) served as the binding matrix to enhance mechanical integrity. The hydrangea-like SiO₂ nanostructures were characterized by solid cores and wrinkled, petal-like outgrowths. This unique morphology not only increased the surface roughness but also provided more active sites for air entrapment, thereby enhancing the coating’s overall performance. The h-SiO₂@PFDT-EP composite coating exhibited excellent superhydrophobicity, with a WCA of 170.1° ± 0.8° and a SA of 2.7° ± 0.5°. Durability was evaluated through sandpaper abrasion, tape peeling, acid and alkali immersion, artificial weathering, and salt spray tests. The results demonstrated that the coating retained stable superhydrophobic performance under various environmental stresses. Compared with bare 6061 aluminum and EP coatings, its corrosion current density was reduced by four and three orders of magnitude, respectively. Furthermore, the coating achieved a maximum drag-reduction rate of 31.01% within a velocity range of 1.31–7.86 m/s. The coating also displayed excellent self-cleaning properties. Owing to its outstanding durability, corrosion resistance, and drag-reducing capability, this one-step fabricated superhydrophobic coating showed great promise for applications in marine engineering and defense. Full article

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27 pages, 6279 KiB

Open AccessArticle

Investigation of the Performance and Fuel Oil Corrosion Resistance of Semi-Flexible Pavement with the Incorporation of Recycled Glass Waste

by Ayman Hassan AL-Qudah, Suhana Koting, Mohd Rasdan Ibrahim and Muna M. Alibrahim

Materials 2025, 18(15), 3442; https://doi.org/10.3390/ma18153442 - 22 Jul 2025

Abstract

Semi-flexible pavement (SFP) is a durable and cost-effective alternative to conventional rigid and flexible pavement and is formed by permeating an open-graded asphalt (OGA) layer with high-fluidity cement grout. The degradation of SFP mattresses due to fuel oil spills can result in significant [...] Read more.

Semi-flexible pavement (SFP) is a durable and cost-effective alternative to conventional rigid and flexible pavement and is formed by permeating an open-graded asphalt (OGA) layer with high-fluidity cement grout. The degradation of SFP mattresses due to fuel oil spills can result in significant maintenance costs. Incorporating glass waste (GW) into the construction of SFPs offers an eco-friendly solution, helping to reduce repair costs and environmental impact by conserving natural resources and minimizing landfill waste. The main objective of this research is to investigate the mechanical performance and fuel oil resistance of SFP composites containing different levels of glass aggregate (GlaSFlex composites). Fine glass aggregate (FGA) was replaced with fine virgin aggregate at levels of 0%, 20%, 40%, 60%, 80%, and 100% by mass. The results indicated the feasibility of utilizing FGA as a total replacement (100%) for fine aggregate in the OGA structural layer of SFPs. At 100% FGA, the composite exhibited excellent mechanical performance and durability, including a compressive strength of 8.93 MPa, a Marshall stability exceeding 38 kN, and a stiffness modulus of 19,091 MPa. Furthermore, the composite demonstrated minimal permanent deformation (0.04 mm), a high residual stability of 94.7%, a residual compressive strength of 83.3%, and strong resistance to fuel spillage with a mass loss rate of less than 1%, indicating excellent durability. Full article

(This article belongs to the Special Issue Advanced Materials for Pavement and Road Infrastructure)

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23 pages, 2364 KiB

Open AccessReview

A Comprehensive Review of Applications and Environmental Risks of Waste Plastics in Asphalt Pavements

by Ju Pan, Jue Li, Bailin Shan, Yongsheng Yao and Chao Huang

Materials 2025, 18(15), 3441; https://doi.org/10.3390/ma18153441 - 22 Jul 2025

Abstract

The global plastic crisis has generated significant interest in repurposing waste plastics as asphalt modifiers, presenting both environmental and engineering advantages. This study offers a comprehensive review of the applications of waste plastics in asphalt, focusing on their types, modification mechanisms, incorporation techniques, [...] Read more.

The global plastic crisis has generated significant interest in repurposing waste plastics as asphalt modifiers, presenting both environmental and engineering advantages. This study offers a comprehensive review of the applications of waste plastics in asphalt, focusing on their types, modification mechanisms, incorporation techniques, and environmental impacts, alongside proposed mitigation strategies. Commonly utilized plastics include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), each affecting asphalt performance differently—enhancing high-temperature stability and fatigue resistance while exhibiting varying levels of compatibility and environmental risks. The incorporation techniques, namely wet and dry processes, differ in terms of efficiency, cost, and environmental footprint: the wet process enhances durability but requires more energy, whereas the dry process is more cost-effective but may lead to uneven dispersion. Environmental concerns associated with these practices include toxic emissions (such as polycyclic aromatic hydrocarbons and volatile organic compounds) during production, microplastic generation through abrasion and weathering, and ecological contamination of soil and water. Mitigation strategies encompass optimizing plastic selection, improving pre-treatment and compatibilization methods, controlling high-temperature processing, and monitoring the spread of microplastics. This review highlights the need for balanced adoption of waste plastic-modified asphalt, emphasizing sustainable practices to maximize benefits while minimizing risks. Full article

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

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