Materials

24 pages, 1569 KiB

Open AccessArticle

Effects of Graphene-Based Nanomaterials on Anaerobic Digestion of Thermally Hydrolyzed Municipal Sewage Sludge

by Luiza Usevičiūtė, Tomas Januševičius, Vaidotas Danila and Mantas Pranskevičius

Materials 2025, 18(15), 3561; https://doi.org/10.3390/ma18153561 - 29 Jul 2025

In this study, the effects of graphene-based nanomaterials—specifically graphene nanoplatelets (GNPs) and graphene oxide (GO) nanosheets—on methane (CH₄) production during anaerobic digestion (AD) of thermally hydrolyzed sewage sludge were investigated. Anaerobic digestion was carried out over a 40-day period under mesophilic [...] Read more.

In this study, the effects of graphene-based nanomaterials—specifically graphene nanoplatelets (GNPs) and graphene oxide (GO) nanosheets—on methane (CH₄) production during anaerobic digestion (AD) of thermally hydrolyzed sewage sludge were investigated. Anaerobic digestion was carried out over a 40-day period under mesophilic conditions in batch digesters with a volume of 2.65 L. The influence of various dosages of GNPs and GO nanosheets on methane yields was assessed, including a comparison between GNPs with different specific surface areas (320 m²/g and 530 m²/g). The highest CH₄ yield (194 mL/g-VS_added) was observed with a GNP dosage of 5 mg/g-TS and a surface area of 530 m²/g, showing an increase of 3.08% compared to the control. This treatment group had the greatest positive effect also on the degradation of organic matter, with total solids (TS) and volatile solids (VS) removal reaching 34.35% and 44.18%, respectively. However, the GO dosages that significantly decreased cumulative CH₄ production were determined to be 10–15 mg/g-TS. Graphene oxide at dosages of 10 and 15 mg/g-TS reduced specific cumulative CH₄ yields by 4.03% and 5.85%, respectively, compared to the control, indicating CH₄ yield inhibition. This lab-scale study highlights the potential for integrating GNPs into full-scale, continuously operated wastewater treatment anaerobic digesters for long-term use in future applications. Full article

(This article belongs to the Special Issue Carbonaceous Materials: Fabrication, Characterization and Applications)

14 pages, 4484 KiB

Open AccessArticle

Influence of Particle Size, Defect Density and Salts on the Dissolution and Early Hydration of a Model System (C₃A + Quartz)

by Shaoxiong Ye and Pan Feng

Materials 2025, 18(15), 3560; https://doi.org/10.3390/ma18153560 - 29 Jul 2025

Abstract

Understanding the hydration behavior of cementitious materials is crucial as it governs the setting, strength development and long-term durability of concrete. This study provides fundamental insights into these processes by investigating the early hydration of tricalcium aluminate (C₃A) with quartz as [...] Read more.

Understanding the hydration behavior of cementitious materials is crucial as it governs the setting, strength development and long-term durability of concrete. This study provides fundamental insights into these processes by investigating the early hydration of tricalcium aluminate (C₃A) with quartz as a novel model system for multiple clinker phases. Employing a multi-technique approach combining conductivity, calorimetry and microscopy, we systematically examine the concurrent effects of product layer formation, C₃A’s particle size and defect density, and salts on dissolution kinetics and early-stage reaction pathways. Results indicate that product layer formation shifted C₃A’s rapid dissolution toward diffusion-controlled regimes. Reduced particle size and increased defect density accelerated the dissolution and hydration kinetics. Sulfates and chlorides differentially altered reaction pathways, with preferential sulfate reactivity driving ettringite formation. These mechanistic insights advance fundamental understanding of the hydration behavior of cementitious material. Full article

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

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24 pages, 2874 KiB

Open AccessArticle

The Impact of Confinement Configurations on the Compressive Behavior of CFRP—Wrapped Concrete Cylinders

by Riad Babba, Abdellah Douadi, Eyad Alsuhaibani, Laura Moretti, Abdelghani Merdas, Saci Dahmani and Mourad Boutlikht

Materials 2025, 18(15), 3559; https://doi.org/10.3390/ma18153559 - 29 Jul 2025

Abstract

Experimental tests on confined concrete specimens are essential to characterize the mechanisms activated under varying degrees of confinement. Such characterization is critical for understanding how full, partial, and non-uniform wrapping configurations influence strength and ductility enhancements. This study investigates the compressive behavior of [...] Read more.

Experimental tests on confined concrete specimens are essential to characterize the mechanisms activated under varying degrees of confinement. Such characterization is critical for understanding how full, partial, and non-uniform wrapping configurations influence strength and ductility enhancements. This study investigates the compressive behavior of concrete cylinders (160 mm × 320 mm) confined using full, partial, and non-uniform carbon fiber-reinforced polymers (CFRP) configurations. In the first phase, all wrapping schemes were applied with equivalent quantities of CFRP, enabling a direct performance comparison under material parity. The results indicate that non-uniform confinement (NUC) achieved approximately 15% higher axial strength than full confinement (FC2) using the same amount of CFRP. In the second phase, the NUC configuration was tested with 25% less CFRP material, yet the reduction in strength was limited to about 3%, demonstrating its superior efficiency. A new predictive model was developed to estimate peak axial stress and strain in CFRP-confined concrete cylinders. Compared to existing models, the proposed model demonstrated greater predictive accuracy (R² = 0.98 for stress and 0.91 for strain) and reduced error metrics (RMSE and scatter index). ANOVA confirmed the statistical significance of the model’s predictions (p < 0.00001 for stress, p = 0.002 for strain). These findings highlight the performance advantages and material efficiency of non-uniform CFRP confinement and support the utility of the proposed model as a practical design tool for developing advanced confinement strategies in structural engineering. Full article

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

22 pages, 2806 KiB

Open AccessArticle

Concrete Obtained with the Viterbo O’Reilly Method for Aggregate Gradation: A Potential Model for Sustainable Design and Reducing Development Costs

by Edinson Murillo Mosquera, Sergio Cifuentes, Juan Carlos Obando, Sergio Neves Monteiro and Henry A. Colorado

Materials 2025, 18(15), 3558; https://doi.org/10.3390/ma18153558 - 29 Jul 2025

Abstract

The following investigation presents concrete cement obtained with the Viterbo O’Reilly Diaz method, introduced to quantify the concrete mixture by using an aggregate gradation method. This research uses this procedure to decrease the amount of cement in the mix, thus reducing the CO [...] Read more.

The following investigation presents concrete cement obtained with the Viterbo O’Reilly Diaz method, introduced to quantify the concrete mixture by using an aggregate gradation method. This research uses this procedure to decrease the amount of cement in the mix, thus reducing the CO₂ footprint and production costs, which directly impact the environmental and economical sustainability of the material. The formulations used structural and general use Portland cements. As aggregates, fine sand and 3/4” gravel were included. Several characterization techniques were used, including granulometry testing for the aggregates, compression strength testing for the concrete samples, and granulometry testing for the raw materials. Compressive tests were conducted on samples after 28 days of curing, while scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) was used to understand the microstructure. The results revealed the optimal amounts of water, cement, and aggregates. Combinations of fine and coarse aggregates were determined as well. The main novelty in this manuscript is the use of the Viterbo O’Reilly mix design method to innovatively enhance concrete mixes by analyzing material properties and behavior in detail, an unexplored method in the literature. This research considers not only strength but also durability and workability, using mathematical tools for data analysis. This data-driven approach ensures effective aggregate gradation towards sustainability when compared to other traditional methods. Full article

(This article belongs to the Special Issue Recycling and Development of New Building Materials or Products (Second Volume))

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36 pages, 4967 KiB

Open AccessReview

Mechanical Behavior of Adhesively Bonded Joints Under Tensile Loading: A Synthetic Review of Configurations, Modeling, and Design Considerations

by Leila Monajati, Aurelian Vadean and Rachid Boukhili

Materials 2025, 18(15), 3557; https://doi.org/10.3390/ma18153557 - 29 Jul 2025

Abstract

This review presents a comprehensive synthesis of recent advances in the tensile performance of adhesively bonded joints, focusing on applied aspects and modeling developments rather than providing a full theoretical analysis. Although many studies have addressed individual joint types or modeling techniques, an [...] Read more.

This review presents a comprehensive synthesis of recent advances in the tensile performance of adhesively bonded joints, focusing on applied aspects and modeling developments rather than providing a full theoretical analysis. Although many studies have addressed individual joint types or modeling techniques, an integrated review that compares joint configurations, modeling strategies, and performance optimization methods under tensile loading remains lacking. This work addresses that gap by examining the mechanical behavior of key joint types, namely, single-lap, single-strap, and double-strap joints, and highlighting their differences in stress distribution, failure mechanisms, and structural efficiency. Modeling and simulation approaches, including cohesive zone modeling, extended finite element methods, and virtual crack closure techniques, are assessed for their predictive accuracy and applicability to various joint geometries. This review also covers material and geometric enhancements, such as adherend tapering, fillets, notching, bi-adhesives, functionally graded bondlines, and nano-enhanced adhesives. These strategies are evaluated in terms of their ability to reduce stress concentrations and improve damage tolerance. Failure modes, adhesive and adherend defects, and delamination risks are also discussed. Finally, comparative insights into different joint configurations illustrate how geometry and adhesive selection influence strength, energy absorption, and weight efficiency. This review provides design-oriented guidance for optimizing bonded joints in aerospace, automotive, and structural engineering applications. Full article

(This article belongs to the Special Issue Advanced Materials and Processing Technologies)

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21 pages, 7398 KiB

Open AccessArticle

Clinch-Bonding Process for Ultra-High-Strength Steel and A5052 Aluminum Alloy Sheets

by Yohei Abe, Yu Tatara, Takahiro Hosokawa and Ryoto Yamauchi

Materials 2025, 18(15), 3556; https://doi.org/10.3390/ma18153556 - 29 Jul 2025

Abstract

Initially, the effects of sheet combinations for joining two sheets, including 780 MPa steel and A5052 aluminum alloy sheets, on the joined cross-sectional shapes of the sheets in a clinch-bonding process and the tension–shear load of joined sheets were investigated. The effect of [...] Read more.

Initially, the effects of sheet combinations for joining two sheets, including 780 MPa steel and A5052 aluminum alloy sheets, on the joined cross-sectional shapes of the sheets in a clinch-bonding process and the tension–shear load of joined sheets were investigated. The effect of an adhesive on the amounts of the interlock and the minimum thickness in the upper sheet was not large, whereas the effect of the sheet combination was observed. Subsequently, for joining the upper 980 MPa ultra-high-strength steel and lower aluminum alloy sheets in the clinch-bonding process, the effects of the die shape, punch velocity, and sheet holding force on the joinability were investigated. As a result, defect-free conditions were narrowly constrained. Finally, a method that involved controlling material flow using an adhesive with fine particles to increase friction between the sheets was introduced. The upper 980 MPa steel and lower aluminum alloy sheets were successfully joined using this approach. Full article

(This article belongs to the Section Metals and Alloys)

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Graphical abstract

18 pages, 4680 KiB

Open AccessArticle

Preparation of Glass-Ceramics Using Zinc-Containing Smelting Slag: Structure, Properties and Solidification of Zinc

by Nannan Wu, Junhui Huang, Junxi Qiu, Zonghang Li, Xiaofan Li, Bohan Li, Nianzhe Li, Yuxuan Zhang and Shunli Ouyang

Materials 2025, 18(15), 3555; https://doi.org/10.3390/ma18153555 - 29 Jul 2025

Abstract

The stabilization of heavy metal elements, such as zinc, in the form of ions within the glass-ceramics represents a valuable approach to addressing environmental pollution caused by heavy metals. This study investigates the feasibility and physicochemical properties of diopside-based glass-ceramics synthesized from zinc-containing [...] Read more.

The stabilization of heavy metal elements, such as zinc, in the form of ions within the glass-ceramics represents a valuable approach to addressing environmental pollution caused by heavy metals. This study investigates the feasibility and physicochemical properties of diopside-based glass-ceramics synthesized from zinc-containing smelting slag. The zinc-rich smelting slag is abundant in SiO₂, Al₂O₃, CaO, and other constituents, thereby providing cost-effective and efficient raw materials for glass-ceramic production. The conversion of zinc-containing smelting slag into glass-ceramics was achieved through a melting process. We analyzed the effects of varying doping levels on the properties of the resulting glass-ceramics. The results indicated that as the doping level of smelting slag increases, the crystallization temperature of the glass-ceramics decreases while the crystal phases of diopside and anorthite progressively increase, significantly enhancing both mechanical strength and chemical stability. Notably, when the doping level reaches 60%, these glass-ceramics exhibit remarkable physical properties, including high density (3.12 g/cm³), Vickers hardness (16.60 GPa), and excellent flexural strength (150.75 MPa). Furthermore, with increasing amounts of doped smelting slag, there are substantial improvements in acid resistance, alkali resistance, and corrosion resistance in these materials. Raman spectroscopy and EDS analysis further verified a uniform distribution of the crystal phase and effective immobilization of heavy metal zinc. Full article

(This article belongs to the Special Issue Sustainable and Green Synthesis of Nanomaterials for Heavy Metal Applications)

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23 pages, 8390 KiB

Open AccessArticle

Autoregulation of Woven Fabric Structure: Image-Based and Regression Analysis of Structural Homogeneity Under Varying Weaving Parameters

by Magdalena Owczarek

Materials 2025, 18(15), 3554; https://doi.org/10.3390/ma18153554 - 29 Jul 2025

Abstract

This study investigates the influence of weaving process parameters on the structural homogeneity of woven fabrics, with a focus on the structural autoregulation phenomenon. Two experimental fabric groups of 30 each, plain and twill weaves, were produced using varied loom settings: shed closure [...] Read more.

This study investigates the influence of weaving process parameters on the structural homogeneity of woven fabrics, with a focus on the structural autoregulation phenomenon. Two experimental fabric groups of 30 each, plain and twill weaves, were produced using varied loom settings: shed closure timing, lease rod position, backrest roller position, warp pre-tension, and yarn twist direction. Structural uniformity was assessed using a proprietary method and the MagFABRIC 2.1. image analysis system, which quantify intra-repeat, inter-repeat, and global inhomogeneity. This method uses the size, shape, and location of inter-thread pores as well as warp and weft pitches. The results indicate that autoregulation can reduce local structural disturbances, including warp yarn grouping. In plain weaves, loom parameters and humidity significantly contributed to structural autoregulation. In contrast, twill weaves demonstrated dominant internal feedback mechanisms, significantly influenced by yarn twist direction. Regression models at F = 10 revealed nonlinear interactions, confirming autoregulation and experimentally supporting Nosek’s quasi-dynamic theory for these types of fabrics. The results of these studies have practical relevance in high-performance textiles such as filtration, barrier fabrics, and composite reinforcements, where local structural deviations critically affect the functional properties of fabrics. Full article

(This article belongs to the Section Advanced Composites)

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28 pages, 1736 KiB

Open AccessArticle

Energy-Efficient Gold Flotation via Coarse Particle Generation Using VSI and HPGR Comminution

by Sindhura Thatipamula and Sheila Devasahayam

Materials 2025, 18(15), 3553; https://doi.org/10.3390/ma18153553 - 29 Jul 2025

Abstract

This study investigates the impact of two comminution technologies—Vertical Shaft Impactors (VSI) and High-Pressure Grinding Rolls (HPGR)—on gold flotation performance, using ore samples from the Ballarat Gold Mine, Australia. The motivation stems from the growing need to improve energy efficiency and flotation recovery [...] Read more.

This study investigates the impact of two comminution technologies—Vertical Shaft Impactors (VSI) and High-Pressure Grinding Rolls (HPGR)—on gold flotation performance, using ore samples from the Ballarat Gold Mine, Australia. The motivation stems from the growing need to improve energy efficiency and flotation recovery in mineral processing, particularly under increasing economic and environmental constraints. Despite the widespread use of HPGR and VSI in the industry, limited comparative studies have explored their effects on downstream flotation behavior. Laboratory-scale experiments were conducted across particle size fractions (300–600 µm) using two collector types—Potassium Amyl Xanthate (PAX) and DSP002 (a proprietary dithiophosphate collector) to assess differences in flotation recovery, concentrate grade, and specific energy consumption. The results reveal that HPGR produces more fines and micro-cracks, enhancing liberation but also increasing gangue entrainment and energy demand. Conversely, VSI produces coarser, cubical particles with fewer slimes, achieving higher flotation grades and recoveries at lower energy input. VSI at 600 µm demonstrated the highest flotation efficiency (4241) with only 9.79 kWh/t energy input. These findings support the development of hybrid or tailored comminution strategies for improved flotation selectivity and sustainable processing. Full article

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

19 pages, 1658 KiB

Open AccessArticle

Examples of Reliability Models of a Renewable Technical Object in Relation to Special Vehicles

by Michał Stawowiak, Aleksander Gwiazda, Santina Topolska and Małgorzata Olender-Skóra

Materials 2025, 18(15), 3552; https://doi.org/10.3390/ma18153552 - 29 Jul 2025

Abstract

The article describes examples of reliability models of a renewable technical object. The proposed models are mathematical models that, according to the author, are best suited to presenting problems resulting from the operation of the analyzed technical objects. These objects are special vehicles, [...] Read more.

The article describes examples of reliability models of a renewable technical object. The proposed models are mathematical models that, according to the author, are best suited to presenting problems resulting from the operation of the analyzed technical objects. These objects are special vehicles, in this case garbage trucks with plate compaction and rear loading of waste containers. The author described two models: one where a model was analyzed and the replacement of a worn part with a brand new part was assumed, and a model where the worn element was repaired (renewed), so that after the repair, the element showed features as if it were a brand new element. Each of the examples was considered based on operational data from city cleaning companies. Data obtained from service books was used for calculations. The analyzed examples are concluded with short conclusions. In turn, the entire article ends with a summary in the form of conclusions resulting from the use of these specific models. The author draws attention to the reasonableness of their use in the scope analyzed by him, and the benefits that result from the use of these models. Full article

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

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26 pages, 3943 KiB

Open AccessFeature PaperArticle

Effect of Corrosion-Induced Damage on Fatigue Behavior Degradation of ZCuAl₈Mn₁₃Fe₃Ni₂ Nickel–Aluminum Bronze Under Accelerated Conditions

by Ruonan Zhang, Junqi Wang, Pengyu Wei, Lian Wang, Chihui Huang, Zeyu Dai, Jinguang Zhang, Chaohe Chen and Xinyan Guo

Materials 2025, 18(15), 3551; https://doi.org/10.3390/ma18153551 - 29 Jul 2025

Abstract

Corrosion fatigue damage significantly affects the long-term service of marine platforms such as propellers. Fatigue testing of pre-corrosion specimens is essential for understanding damage mechanisms and accurately predicting fatigue life. However, traditional seawater-based tests are time-consuming and yield inconsistent results, making them unsuitable [...] Read more.

Corrosion fatigue damage significantly affects the long-term service of marine platforms such as propellers. Fatigue testing of pre-corrosion specimens is essential for understanding damage mechanisms and accurately predicting fatigue life. However, traditional seawater-based tests are time-consuming and yield inconsistent results, making them unsuitable for rapid evaluation of newly developed equipment. This study proposes an accelerated corrosion testing method for ZCuAl₈Mn₁₃Fe₃Ni₂ nickel–aluminum bronze, simulating the marine full immersion zone by increasing temperature, adding H₂O₂, reducing the solution pH, and preparing the special solution. Coupled with the fatigue test of pre-corrosion specimens, the corrosion damage characteristics and their influence on fatigue performance were analyzed. A numerical simulation method was developed to predict the fatigue life of pre-corrosion specimens, showing an average error of 13.82%. The S–N curves under different pre-corrosion cycles were also established. The research results show that using the test solution of 0.6 mol/L NaCl + 0.1 mol/L H₃PO₄-NaH₂PO₄ buffer solution + 1.0 mol/L H₂O₂ + 0.1 mL/500 mL concentrated hydrochloric acid for corrosion acceleration testing shows good corrosion acceleration. Moreover, the test methods ensure accuracy and reliability of the fatigue behavior evaluation of pre-corrosion specimens of the structure under actual service environments, offering a robust foundation for the material selection, corrosion resistance evaluation, and fatigue life prediction of marine structural components. Full article

(This article belongs to the Special Issue Design, Mechanical Properties, and Fatigue Behavior of Materials, Welding Joints and Structures)

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13 pages, 1041 KiB

Open AccessArticle

Synthesis and FT-IR/Raman Characterization of a Graphene Oxide–Methacrylamide Monomer for Dental Applications

by Gennaro Ruggiero, Davide Di Rosa, Francesco Caso, Roberto Sorrentino, Fernando Zarone and Giuseppe Caso

Materials 2025, 18(15), 3550; https://doi.org/10.3390/ma18153550 - 29 Jul 2025

Abstract

Background: Graphene oxide (GO) is widely explored as a functional additive in polymer composites; however, its simple physical dispersion in dental resins often leads to poor interfacial stability and limited long-term performance. Covalent functionalization may overcome these limitations by enabling chemical integration into [...] Read more.

Background: Graphene oxide (GO) is widely explored as a functional additive in polymer composites; however, its simple physical dispersion in dental resins often leads to poor interfacial stability and limited long-term performance. Covalent functionalization may overcome these limitations by enabling chemical integration into the polymer matrix. This study presents the synthesis and FT-IR/Raman characterization of GRAPHYMERE^®, a novel graphene oxide-based monomer obtained through exfoliation, amine functionalization with 1,6-hexanediamine, and transamidation with methyl methacrylate. Methods: A novel GO-based monomer, GRAPHYMERE^®, was synthesized through a three-step process involving GO exfoliation, amine functionalization with 1,6-hexanediamine, and transamidation with methyl methacrylate to introduce polymerizable acrylic groups. The resulting product was characterized using FT-IR and Raman spectroscopy. Results: Spectroscopic analyses confirmed the presence of aliphatic chains and amine functionalities on the GO surface. Although some expected signals were overlapped, the data suggest successful surface modification and partial insertion of methacrylamide groups. The process is straightforward, uses low-toxicity reagents, and avoids complex reaction steps. Conclusions: GRAPHYMERE^® represents a chemically modified GO monomer potentially suitable for copolymerization within dental resin matrices. While its structural features support compatibility with radical polymerization systems, further studies are required to assess its mechanical performance and functional properties in dental resin applications. Full article

(This article belongs to the Special Issue Advanced Biomaterials for Medical Applications (2nd Edition))

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26 pages, 23183 KiB

Open AccessArticle

Fracture Behaviour of Basalt Fibre-Reinforced Lightweight Geopolymer Concrete: A Multidimensional Analysis

by Jutao Tao, Mingxia Jing, Qingshun Yang and Feng Liang

Materials 2025, 18(15), 3549; https://doi.org/10.3390/ma18153549 - 29 Jul 2025

Abstract

This study introduced basalt fibres as a reinforcing material and employed notched beam three-point bending tests combined with digital image correlation (DIC) technology to comprehensively evaluate key fracture parameters—namely, initial fracture toughness, unstable fracture toughness, fracture energy, and ductility index—of expanded polystyrene (EPS)-based [...] Read more.

This study introduced basalt fibres as a reinforcing material and employed notched beam three-point bending tests combined with digital image correlation (DIC) technology to comprehensively evaluate key fracture parameters—namely, initial fracture toughness, unstable fracture toughness, fracture energy, and ductility index—of expanded polystyrene (EPS)-based geopolymer concrete with different mix proportions. The results demonstrate that the optimal fracture performance was achieved when the basalt fibre volume content was 0.4% and the EPS content was 20%, resulting in respective increases of 12.07%, 28.73%, 98.92%, and 111.27% in the above parameters. To investigate the toughening mechanisms, scanning electron microscopy was used to observe the fibre–matrix interfacial bonding and crack morphology, while X-ray micro-computed tomography enabled detailed three-dimensional visualisation of internal porosity and crack development, confirming the crack-bridging and energy-dissipating roles of basalt fibres. Furthermore, the crack propagation process was simulated using the extended finite element method, and the evolution of fracture-related parameters was quantitatively analysed using a linear superposition progressive assumption. A simplified predictive model was proposed to estimate fracture toughness and fracture energy based on the initial cracking load, peak load, and compressive strength. The findings provide theoretical support and practical guidance for the engineering application of basalt fibre-reinforced EPS-based geopolymer lightweight concrete. Full article

(This article belongs to the Special Issue Advanced Cement-Based Composite Materials and Composite Intelligent Design)

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18 pages, 4254 KiB

Open AccessArticle

Testing Using the DCP Probe of a Subgrade Modeled from Difficult-to-Compact Sand in a Calibration Chamber

by Dariusz Tymosiak, Maria Jolanta Sulewska, Wanda Kokoszka, Marta Słowik, Ewa Błazik-Borowa, Dominik Ożóg and Monika Puchlik

Materials 2025, 18(15), 3548; https://doi.org/10.3390/ma18153548 - 29 Jul 2025

Abstract

The aim of the article is to analyze the possibilities of using a lightweight dynamic cone probe DCP to determine the quality of compaction of surface layers of embankments (from 0.10 m to approx. 0.80 m below ground level). For this purpose, comparative [...] Read more.

The aim of the article is to analyze the possibilities of using a lightweight dynamic cone probe DCP to determine the quality of compaction of surface layers of embankments (from 0.10 m to approx. 0.80 m below ground level). For this purpose, comparative tests of non-cohesive soil used for the construction of embankments were carried out using the DCP test and direct tests of the degree of compaction I_S in a calibration chamber with the following dimensions: height 1.10 m and diameter 0.75 m. The subsoil was prepared from difficult-to-compact sand (Sa) with a uniformity coefficient of C_U = 3.10 and curvature coefficient of C_C = 0.99. The soil in the laboratory in the calibration chamber was compacted in layers using a vibratory plate compactor. A database for statistical analysis was obtained, n = 68 cases described by seven variables: z, ρ, w, ρ_d, I_S, PI, N₁₀(DCP). It was found that the DCP probe can be used to assess the degree of compaction of embankments made of non-cohesive soil, using the developed relationship I_S = f(z, N₁₀(DCP)). Full article

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

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13 pages, 3623 KiB

Open AccessArticle

Fabrication and Characterization of Ferroelectric Capacitors with a Symmetric Hybrid TiN/W/HZO/W/TiN Electrode Structure

by Ha-Jung Kim, Jae-Hyuk Choi, Seong-Eui Lee, So-Won Kim and Hee-Chul Lee

Materials 2025, 18(15), 3547; https://doi.org/10.3390/ma18153547 - 29 Jul 2025

Abstract

In this study, Hf_0.5Zr_0.5O₂ (HZO) thin-films were deposited using a Co-plasma atomic layer deposition (CPALD) process that combined both remote plasma and direct plasma, for the development of ferroelectric memory devices. Ferroelectric capacitors with a symmetric hybrid TiN/W/HZO/W/TiN [...] Read more.

In this study, Hf_0.5Zr_0.5O₂ (HZO) thin-films were deposited using a Co-plasma atomic layer deposition (CPALD) process that combined both remote plasma and direct plasma, for the development of ferroelectric memory devices. Ferroelectric capacitors with a symmetric hybrid TiN/W/HZO/W/TiN electrode structure, incorporating W electrodes as insertion layers, were fabricated. Rapid thermal annealing (RTA) was subsequently employed to control the crystalline phase of the films. The electrical and structural properties of the capacitors were analyzed based on the RTA temperature, and the presence, thickness, and position of the W insertion electrode layer. Consequently, the capacitor with 5 nm-thick W electrode layers inserted on both the top and bottom sides and annealed at 700 °C exhibited the highest remnant polarization (2P_r = 61.0 μC/cm²). Moreover, the symmetric hybrid electrode capacitors annealed at 500–600 °C also exhibited high 2P_r values of approximately 50.4 μC/cm², with a leakage current density of approximately 4 × 10⁻⁵ A/cm² under an electric field of 2.5 MV/cm. The findings of this study are expected to contribute to the development of electrode structures for improved performance of HZO-based ferroelectric memory devices. Full article

(This article belongs to the Special Issue Eco-Sustainable Designing of Metal Oxide Thin Films with High Properties Using Advanced Micro–and Nanofabrication Technologies)

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21 pages, 2695 KiB

Open AccessArticle

Thermographic Investigation of Elastocaloric Behavior in Ni-Ti Sheet Elements Under Cyclic Bending

by Saeed Danaee Barforooshi, Gianmarco Bizzarri, Girolamo Costanza, Stefano Paoloni, Ilaria Porroni and Maria Elisa Tata

Materials 2025, 18(15), 3546; https://doi.org/10.3390/ma18153546 - 29 Jul 2025

Abstract

Growing environmental concerns have driven increased interest in solid-state thermal technologies based on the elastocaloric properties of shape memory alloys (SMA). This work examines the elastocaloric effect (eCE) in Ni-Ti SMA sheets subjected to cyclic bending, providing quantitative thermal characterization of their behavior [...] Read more.

Growing environmental concerns have driven increased interest in solid-state thermal technologies based on the elastocaloric properties of shape memory alloys (SMA). This work examines the elastocaloric effect (eCE) in Ni-Ti SMA sheets subjected to cyclic bending, providing quantitative thermal characterization of their behavior under controlled loading conditions. The experimental investigation employed passive thermography to analyze the thermal response of Ni-Ti sheets under two deflection configurations at 1800 rpm loading. Testing revealed consistent adiabatic temperature variations (ΔT_ad) of 4.14 °C and 4.26 °C for the respective deflections during heating cycles, while cooling phases demonstrated efficient thermal homogenization with temperature gradients decreasing from 4.13 °C to 0.13 °C and 4.43 °C to 0.68 °C over 60 s. These findings provide systematic thermal documentation of elastocaloric behavior in bending-loaded Ni-Ti sheet elements and quantitative data on the relationship between mechanical loading parameters and thermal gradients, enhancing the experimental understanding of elastocaloric phenomena in this configuration. Full article

(This article belongs to the Special Issue Technology and Applications of Shape Memory Materials)

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22 pages, 5743 KiB

Open AccessArticle

Effect of Grain Boundary Characteristics on Mechanical Properties and Irradiation Response in 3C-SiC: A Molecular Dynamics Simulation Study

by Wenying Liu, Fugen Deng, Jiajie Yu, Lin Chen, Yuyang Zhou, Yulu Zhou and Yifang Ouyang

Materials 2025, 18(15), 3545; https://doi.org/10.3390/ma18153545 - 29 Jul 2025

Abstract

Molecular dynamics (MD) simulations have been performed on the energetics, mechanical properties, and irradiation response of seventy-three 3C-SiC symmetric tilt grain boundaries (STGBs) with three tilt axes (<100>, <110> and <111>). The effect of GB characteristics on the STGB properties has been investigated. [...] Read more.

Molecular dynamics (MD) simulations have been performed on the energetics, mechanical properties, and irradiation response of seventy-three 3C-SiC symmetric tilt grain boundaries (STGBs) with three tilt axes (<100>, <110> and <111>). The effect of GB characteristics on the STGB properties has been investigated. The GB energy is positively and linearly correlated with the excess volume, but the linearity in SiC is not as good as in metals, which stems from the inhomogeneous structural relaxation near GBs induced by orientation-sensitive covalent bonding. For <110>STGBs, the shear strength exhibits symmetry with respect to the misorientation angle of 90°, which is consistent with ab initio calculations for Al in similar shear orientations. Cascades are performed with 8 keV silicon as the primary knock-on atom (PKA). No direct correlation is found between the sink efficiency of GBs for defects and GB characteristics, which comes from the complexity of the diatomic system during the recovery phase. For GBs with smaller values of Σ, the GBs exhibit a weaker blocking effect on the penetration of irradiated defects, resulting in a lower number of defects in GBs and a higher number of total surviving defects. In particular, it is seen that the percentage decrease in tensile strength after irradiation is positively correlated with the Σ value. Taken together, these results help to elucidate the impact of GB behavior on the mechanical properties of as well as the primary irradiation damage in SiC and provide a reference for creating improved materials through GB engineering. Full article

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

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19 pages, 7490 KiB

Open AccessArticle

Effect of Chemical Etching on the Supercapacitive Performance of Electroless Ni-B Coatings

by Mate Czagany, Gabor Meszaros, Daniel Koncz-Horvath, Adrienn Hlavacs, Mark Windisch, Byungil Hwang and Peter Baumli

Materials 2025, 18(15), 3544; https://doi.org/10.3390/ma18153544 - 29 Jul 2025

Abstract

In our study, supercapacitor electrodes were prepared by depositing electroless Ni-B coating on copper plates, followed by nitric acid etching. The composition and the micro- and phase structure of the coatings were investigated by ICP-OES, PFIB-SEM, and XRD techniques. The original pebble-like structure [...] Read more.

In our study, supercapacitor electrodes were prepared by depositing electroless Ni-B coating on copper plates, followed by nitric acid etching. The composition and the micro- and phase structure of the coatings were investigated by ICP-OES, PFIB-SEM, and XRD techniques. The original pebble-like structure of the coating consists of 0.8–10 µm particles, with an X-ray amorphous phase structure. The surface morphology and porosity of the coating can be tuned simply by changing the etching time. The supercapacitive performance of the electrodes was evaluated by means of cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy measurements. The capacitance of the coating was found to vary on the etching time according to a maximum function, allowing for the determination of an optimal duration to obtain a specific capacitance of 157 mF/cm² (at 0.5 A/g). An excellent charge storage retention of 178% was found after 5000 CV cycles at a scan rate of 50 mV/s owing to the evolved electrochemically active network on the surface of the electrode, indicating a long-term stable and reliable electrode. Full article

(This article belongs to the Section Energy Materials)

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15 pages, 1812 KiB

Open AccessArticle

Influence of Digital Manufacturing and Abutment Design on Full-Arch Implant Prostheses—An In Vitro Study

by Shahad Altwaijri, Hanan Alotaibi, Talal M. Alnassar and Alhanoof Aldegheishem

Materials 2025, 18(15), 3543; https://doi.org/10.3390/ma18153543 - 29 Jul 2025

Abstract

Achieving accurate fit in implant-supported prostheses is critical for avoiding mechanical complications; however, the influence of digital manufacturing techniques and abutment designs on misfit and preload remains unclear. This study evaluated the impact of different manufacturing techniques (CAD-cast and 3D printing) and abutment [...] Read more.

Achieving accurate fit in implant-supported prostheses is critical for avoiding mechanical complications; however, the influence of digital manufacturing techniques and abutment designs on misfit and preload remains unclear. This study evaluated the impact of different manufacturing techniques (CAD-cast and 3D printing) and abutment connection types (engaging [E], non-engaging [NE]) on the misfit and preload of implant-supported cantilevered fixed dental prostheses (ICFDPs). Misfit was measured at six points using scanning electron microscopy, and preload was assessed via eight strain gauges placed buccally and lingually on four implants. Frameworks were torqued to 35 Ncm, retorqued after 10 min, and subjected to 200,000 cycles of loading. Mean preload values ranged from 173.4 ± 79.5 Ncm (PF) to 330 ± 253.2 Ncm (3DP). Preload trends varied depending on the abutment type and manufacturing technique, with the 3DP group showing higher preload in engaging (E) abutments, whereas the CAD-cast group showed the opposite pattern. Although preload values varied numerically, these differences were not statistically significant (p = 0.5). In terms of misfit, significant differences were observed between groups (p < 0.05), except between CAD-cast E (86.4 ± 17.8 μm) and 3DP E (84.1 ± 19.2 μm). Additionally, E and NE abutments showed significant differences in misfit within both CAD-cast and 3DP groups. Overall, 3DP frameworks showed superior fit over CAD-cast. These findings suggest that 3DP may offer improved clinical outcomes in terms of implant–abutment fit. Full article

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