Materials

22 pages, 13284 KiB

Open AccessArticle

Mechanical Properties of CuZr Amorphous Metallic Nanofoam at Various Temperatures Investigated by Molecular Dynamics Simulation

by Yuhang Zhang, Hongjian Zhou and Xiuming Liu

Materials 2025, 18(14), 3423; https://doi.org/10.3390/ma18143423 - 21 Jul 2025

Viewed by 438

Abstract

Metallic nanofoams with amorphous structures demonstrate exceptional properties and significant potential for diverse applications. However, their mechanical properties at different temperatures are still unclear. By using molecular dynamics simulation, this study investigates the mechanical responses of representative CuZr amorphous metallic nanofoam (AMNF) under [...] Read more.

Metallic nanofoams with amorphous structures demonstrate exceptional properties and significant potential for diverse applications. However, their mechanical properties at different temperatures are still unclear. By using molecular dynamics simulation, this study investigates the mechanical responses of representative CuZr amorphous metallic nanofoam (AMNF) under uniaxial tension and compression at various temperatures. Our results reveal that the mechanical properties, such as Young’s modulus, yield stress, and maximum stress, exhibit notable temperature sensitivity and tension–compression asymmetry. Under tensile loading, the Young’s modulus, yield strength, and peak stress exhibit significant reductions of approximately 30.5%, 33.3%, and 32.9%, respectively, as the temperature increases from 100 K to 600 K. Similarly, under compressive loading, these mechanical properties experience even greater declines, with the Young’s modulus, yield strength, and peak stress decreasing by about 34.5%, 38.0%, and 41.7% over the same temperature range. The tension–compression asymmetry in yield strength is temperature independent. Interestingly, the tension–compression asymmetry in elastic modulus becomes more pronounced at elevated temperatures, which is attributed to the influence of surface energy effects. This phenomenon is further amplified by the increased disparity in surface-area-to-volume ratio variations between tensile and compressive loading at higher temperatures. Additionally, as the temperature rises, despite material softening, the structural resistance under large tensile strains improves due to delayed ligament degradation and more uniform deformation distribution, delaying global failure. Full article

(This article belongs to the Section Mechanics of Materials)

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17 pages, 3437 KiB

Open AccessArticle

Effects of Heavy-Metal-Sludge Sintered Aggregates on the Mechanical Properties of Ultra-High-Strength Concrete

by Weijun Zhong, Sheng Wang, Yue Chen, Nan Ye, Kai Shu, Rongnan Dai and Mingfang Ba

Materials 2025, 18(14), 3422; https://doi.org/10.3390/ma18143422 - 21 Jul 2025

Viewed by 214

Abstract

To investigate the effects of heavy-metal-sludge sintered aggregates on the workability, mechanical properties, and fracture toughness of ultra-high-strength concrete (UHSC), this study systematically evaluated the influence of different aggregate replacement ratios and particle gradations on the fluidity, flexural strength, compressive strength, and fracture [...] Read more.

To investigate the effects of heavy-metal-sludge sintered aggregates on the workability, mechanical properties, and fracture toughness of ultra-high-strength concrete (UHSC), this study systematically evaluated the influence of different aggregate replacement ratios and particle gradations on the fluidity, flexural strength, compressive strength, and fracture energy of UHSC. Microstructural characterization techniques including SEM, XRD, TG, and FTIR were employed to analyze the hydration mechanism and interfacial transition zone evolution. The results demonstrated the following: Fluidity continuously improved with the increase in the sintered aggregate replacement ratio, with coarse aggregates exhibiting the most significant enhancement due to the “ball-bearing effect” and paste enrichment. The mechanical properties followed a trend of an initial increase followed by a decrease, peaking at 15–20% replacement ratio, at which flexural strength, compressive strength, and fracture energy were optimally enhanced; excessive replacement led to strength reduction owing to skeletal structure weakening, with coarse aggregates providing superior improvement. Microstructural analysis revealed that the sintered aggregates accelerated hydration reactions, promoting the formation of C-S-H gel and Ca(OH)₂, thereby densifying the ITZ. This study identified 15–20% of coarse sintered aggregates as the optimal replacement ratio, which synergistically improved the workability, mechanical properties, and fracture toughness of UHSC. Full article

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

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21 pages, 17998 KiB

Open AccessArticle

Change in the Structural and Mechanical State of Heat-Resistant 15CrMoV5-10 Steel of TPP Steam Pipelines Under the Influence of Operational Factors

by Oleksandra Student, Halyna Krechkovska, Robert Pała and Ivan Tsybailo

Materials 2025, 18(14), 3421; https://doi.org/10.3390/ma18143421 - 21 Jul 2025

Viewed by 270

Abstract

The operational efficiency of the main steam pipelines at thermal power plants is reduced due to several factors, including operating temperature, pressure, service life, and the frequency of process shutdowns, which contribute to the degradation of heat-resistant steels. The study aims to identify [...] Read more.

The operational efficiency of the main steam pipelines at thermal power plants is reduced due to several factors, including operating temperature, pressure, service life, and the frequency of process shutdowns, which contribute to the degradation of heat-resistant steels. The study aims to identify the features of changes in the sizes of grains and carbides along their boundaries, as well as mechanical properties (hardness, strength, plasticity and fracture toughness) along the wall thickness of both pipes in the initial state and after operation with block shutdowns. Preliminary electrolytic hydrogenation of specimens (before tensile tests in air) showed even more clearly the negative consequences of operational degradation of steel. The degradation of steel was also assessed using fracture toughness (J_IC). The value of J_IC for operated steel with a smaller number of shutdowns decreased by 32–33%, whereas with a larger number of shutdowns, its decrease in the vicinity of the outer and inner surfaces of the pipe reached 65 and 61%, respectively. Fractographic signs of more intense degradation of steel after a greater number of shutdowns were manifested at the stage of spontaneous fracture of specimens by changing the mechanism from transgranular cleavage to intergranular, which indicated a decrease in the cohesive strength of grain boundaries. Full article

(This article belongs to the Special Issue Assessment of the Strength of Materials and Structure Elements)

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13 pages, 4489 KiB

Open AccessArticle

Fatigue Resistance of Customized Implant-Supported Restorations

by Ulysses Lenz, Renan Brandenburg dos Santos, Megha Satpathy, Jason A. Griggs and Alvaro Della Bona

Materials 2025, 18(14), 3420; https://doi.org/10.3390/ma18143420 - 21 Jul 2025

Viewed by 310

Abstract

The design of custom abutments (CA) can affect the mechanical reliability of implant-supported restorations. The purpose of the study was to evaluate the influence of design parameters on the fatigue limit of CA and to compare optimized custom designs with the reference abutment [...] Read more.

The design of custom abutments (CA) can affect the mechanical reliability of implant-supported restorations. The purpose of the study was to evaluate the influence of design parameters on the fatigue limit of CA and to compare optimized custom designs with the reference abutment (RA). A morse-tapered dental implant, an anatomical abutment, and a connector screw were digitalized using microcomputed tomography. A cone beam computed tomography scan was obtained from one of the authors to virtually place the implant-abutment assembly in the upper central incisor. Ten design parameters were selected according to the structural geometry of the RA and the implant planning. A reverse-engineered RA model was created in SOLIDWORKS and was modified considering a Taguchi orthogonal array to generate 36 CAs with ±20% dimensional variations. Finite element analysis was conducted in ABAQUS, and fatigue limits were estimated using Fe-safe. ANOVA (α = 0.1) identified the most influential parameters. Von Mises stress values ranged from 229 MPa to 302 MPa, and 94.4% of the CAs had a higher fatigue limit than the RA. Three parameters significantly affected the fatigue performance of the implant system. The design process of custom abutments includes critical design parameters that can be optimized for longer lifetimes of implant-abutment restorations. Full article

(This article belongs to the Special Issue Innovations in Digital Dentistry: Novel Materials and Technologies)

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15 pages, 2806 KiB

Open AccessArticle

Ni-MOF/g-C₃N₄ S-Scheme Heterojunction for Efficient Photocatalytic CO₂ Reduction

by Muhammad Sabir, Mahmoud Sayed, Iram Riaz, Guogen Qiu, Muhammad Tahir, Khuloud A. Alibrahim and Wang Wang

Materials 2025, 18(14), 3419; https://doi.org/10.3390/ma18143419 - 21 Jul 2025

Viewed by 486

Abstract

The rapid recombination of photoinduced charge carriers in semiconductors remains a significant challenge for their practical application in photocatalysis. This study presents the design of a step-scheme (S-scheme) heterojunction composed of carbon nitride (g-C₃N₄) and nickel-based metal–organic framework (Ni-MOF) [...] Read more.

The rapid recombination of photoinduced charge carriers in semiconductors remains a significant challenge for their practical application in photocatalysis. This study presents the design of a step-scheme (S-scheme) heterojunction composed of carbon nitride (g-C₃N₄) and nickel-based metal–organic framework (Ni-MOF) to achieve enhanced charge separation. The establishment of an S-scheme charge transfer configuration at the interface of the Ni-MOF/g-C₃N₄ heterostructure plays a pivotal role in enabling efficient charge carrier separation, and hence, high CO₂ photoreduction efficiency with a CO evolution rate of 1014.6 µmol g⁻¹ h⁻¹ and selectivity of 95% under simulated solar illumination. CO evolution represents an approximately 3.7-fold enhancement compared to pristine Ni-MOF. Density functional theory (DFT) calculations, supported by in situ irradiated X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) experimental results, confirmed the establishment of a well-defined and strongly bonded interface, which improves the charge transfer and separation following the S-scheme mechanism. This study sheds light on MOF-based S-scheme heterojunctions as fruitful and selective alternatives for practical CO₂ photoreduction. Full article

(This article belongs to the Section Energy Materials)

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20 pages, 1666 KiB

Open AccessArticle

Optimized Design of Low-Carbon Fly Ash–Slag Composite Concrete Considering Carbonation Durability and CO₂ Concentration Rising Impacts

by Kang-Jia Wang, Seung-Jun Kwon and Xiao-Yong Wang

Materials 2025, 18(14), 3418; https://doi.org/10.3390/ma18143418 - 21 Jul 2025

Viewed by 320

Abstract

Fly ash and slag are widely used as mineral admixtures to partially replace cement in low-carbon concrete. However, such composite concretes often exhibit a greater carbonation depth than plain Portland concrete with the same 28-day strength, increasing the risk of steel reinforcement corrosion. [...] Read more.

Fly ash and slag are widely used as mineral admixtures to partially replace cement in low-carbon concrete. However, such composite concretes often exhibit a greater carbonation depth than plain Portland concrete with the same 28-day strength, increasing the risk of steel reinforcement corrosion. Previous mix design methods have overlooked this issue. This study proposes an optimized design method for fly ash–slag composite concrete, considering carbonation exposure classes and CO₂ concentrations. Four exposure classes are addressed—XC1 (completely dry or permanently wet environments such as indoor floors or submerged concrete), XC2 (wet but rarely dry, e.g., inside water tanks), XC3 (moderate humidity, e.g., sheltered outdoor environments), and XC4 (cyclic wet and dry, e.g., bridge decks and exterior walls exposed to rain). Two CO₂ levels—0.04% (ambient) and 0.05% (elevated)—were also considered. In Scenario 1 (no durability constraint), the optimized designs for all exposure classes were identical, with 60% slag and 75% total fly ash–slag replacement. In Scenario 2 (0.04% CO₂ with durability), the designs for XC1 and XC2 remained the same, but for XC3 and XC4, the carbonation depth became the controlling factor, requiring a higher binder content and leading to compressive strengths exceeding the target. In Scenario 3 (0.05% CO₂), despite the increased carbonation depth, the XC1 and XC2 designs were unchanged. However, XC3 and XC4 required further increases in binder content and actual strength to meet durability limits. Overall, compressive strength governs the design for XC1 and XC2, while carbonation durability is critical for XC3 and XC4. Increasing the water-to-binder ratio reduces strength, while higher-strength mixes emit more CO₂ per cubic meter, confirming the proposed method’s engineering validity. Full article

(This article belongs to the Special Issue Artificial Intelligence (AI)-Driven Full Lifecycle Management of Infrastructures: From Advanced Cementitious Materials to Durable Structures)

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29 pages, 8058 KiB

Open AccessArticle

Hydrogen Embrittlement Behavior and Applicability of X52 Steel in Pure Hydrogen Pipelines

by Tianlei Li, Honglin Zhang, Wentao Hu, Ke Li, Yaxi Wang and Yuanhua Lin

Materials 2025, 18(14), 3417; https://doi.org/10.3390/ma18143417 - 21 Jul 2025

Viewed by 255

Abstract

This study investigates the mechanical behavior of X52 steel pipes and their weld regions under pure hydrogen transport conditions, with a focus on assessing potential hydrogen embrittlement risks. Through experimental analysis, the research evaluates how different pipeline regions—including the base metal, weld metal, [...] Read more.

This study investigates the mechanical behavior of X52 steel pipes and their weld regions under pure hydrogen transport conditions, with a focus on assessing potential hydrogen embrittlement risks. Through experimental analysis, the research evaluates how different pipeline regions—including the base metal, weld metal, and heat-affected zones—respond to varying hydrogen pressures. Key mechanical properties such as elongation, fracture toughness, and crack growth resistance are analyzed to determine their implications for structural integrity and safety. Based on the findings, this study proposes criteria for the safety evaluation of X52 pipelines operating in hydrogen service environments. The results are intended to inform decisions regarding the repurposing of existing pipelines or the design of new infrastructure dedicated to pure hydrogen transport, offering insights into material performance and critical safety considerations for hydrogen pipeline applications. Full article

(This article belongs to the Section Mechanics of Materials)

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20 pages, 2239 KiB

Open AccessArticle

Synthesis of Biomass Polycarboxylate Superplasticizer and Its Performance on Cement-Based Materials

by Zefeng Kou, Kaijian Huang, Muhua Chen, Hongyan Chu, Linye Zhou and Tianqi Yin

Materials 2025, 18(14), 3416; https://doi.org/10.3390/ma18143416 - 21 Jul 2025

Viewed by 370

Abstract

Polycarboxylate superplasticizer (PCE) is an important part of improving the overall performance of concrete. However, its synthetic raw materials are overly dependent on petrochemical products, and it also causes problems such as environmental pollution. With the development of the building material industry, the [...] Read more.

Polycarboxylate superplasticizer (PCE) is an important part of improving the overall performance of concrete. However, its synthetic raw materials are overly dependent on petrochemical products, and it also causes problems such as environmental pollution. With the development of the building material industry, the demand for petrochemical resources required for synthetic water-reducing agents will increase rapidly. Therefore, there is an urgent need to transition the synthetic raw materials of PCE from petrochemicals to biomass materials to reduce the consumption of nonrenewable resources as well as the burden on the environment. Biomass materials are inexpensive, readily available and renewable. Utilizing biomass resources to develop good-performing water-reducing agents can reduce the consumption of fossil resources. This is conducive to carbon emission reduction in the concrete material industry. In addition, it promotes the high-value utilization of biomass resources. Therefore, in this study, a biomass polyether monomer, acryloyl hydroxyethyl cellulose (AHEC), was synthesized from cellulose via the reaction route of ethylene oxide (EO) etherification and acrylic acid (AA) esterification. Biomass polycarboxylate superplasticizers (PCE-Cs) were synthesized through free radical polymerization by substituting AHEC for a portion of the frequently utilized polyether monomer isopentenyl polyoxyethylene ether (TPEG). This study primarily focused on the properties of PCE-Cs in relation to cement. The findings of this study indicated that the synthesized PCE-C5 at a dosing of 0.4% (expressed as mass fraction of cement) when the AHEC substitution ratio was 5% achieved good water reduction properties and significant delays. With the same fluidity, PCE-C5 could enhance the mechanical strength of cement mortar by 30% to 40%. This study utilized green and low-carbon biomass resources to develop synthetic raw materials for water-reducing agents, which exhibited effective water-reducing performance and enhanced the utilization rate of biomass resources, demonstrating significant application value. Full article

(This article belongs to the Special Issue Green and Sustainable Infrastructure Construction Materials (2nd Edition))

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15 pages, 7394 KiB

Open AccessCommunication

Experimental Investigation of Delayed Fracture Initiation in Advanced High-Strength Steel Under Accelerated Bending

by Kyucheol Jeong, Jaewook Lee and Jonghun Yoon

Materials 2025, 18(14), 3415; https://doi.org/10.3390/ma18143415 - 21 Jul 2025

Viewed by 296

Abstract

Predicting bending fractures in advanced high-strength steel (AHSS) is challenging due to complex microstructural behaviors and strain rate dependencies, particularly in industrial forming processes. Current models and standards primarily focus on quasi-static tension or slow bending speeds, leaving a gap in understanding the [...] Read more.

Predicting bending fractures in advanced high-strength steel (AHSS) is challenging due to complex microstructural behaviors and strain rate dependencies, particularly in industrial forming processes. Current models and standards primarily focus on quasi-static tension or slow bending speeds, leaving a gap in understanding the accelerated failure of AHSS without necking. In this study, direct bending experiments were conducted on dual-phase, complex-phase, and martensitic AHSS grades under varying bending speeds and radii. Since the bending crack is irrelevant to the load drop, surface crack evolution was measured using three-dimensional surface profile analysis. The results showed that accelerated bending significantly delayed crack initiation across all tested materials, with small-radius bending showing reduced strain localization due to strain rate hardening. Larger-radius bending benefited primarily from increased fracture strain. Full article

(This article belongs to the Special Issue Advanced High-Strength Steels: Processing and Characterization)

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21 pages, 18567 KiB

Open AccessArticle

Mitigation of Black Streak Defects in AISI 304 Stainless Steel via Numerical Simulation and Reverse Optimization Algorithm

by Xuexia Song, Xiaocan Zhong, Wanlin Wang and Kun Dou

Materials 2025, 18(14), 3414; https://doi.org/10.3390/ma18143414 - 21 Jul 2025

Viewed by 308

Abstract

The formation mechanism of black streak defects in hot-rolled steel sheets was investigated to address the influence of the process parameters on the surface quality during the production of 304 stainless steels. Macro-/microstructural characterization revealed that the defect regions contained necessary mold slag [...] Read more.

The formation mechanism of black streak defects in hot-rolled steel sheets was investigated to address the influence of the process parameters on the surface quality during the production of 304 stainless steels. Macro-/microstructural characterization revealed that the defect regions contained necessary mold slag components (Ca, Si, Al, Mg, Na, K) which originated from the initial stage of solidification in the mold region of the continuous casting process, indicating obvious slag entrapment during continuous casting. On this basis, a three-dimensional coupled finite-element model for the molten steel flow–thermal characteristics was established to evaluate the effects of typical casting parameters using the determination of the critical slag entrapment velocity as the criterion. Numerical simulations demonstrated that the maximum surface velocity improved from 0.29 m/s to 0.37 m/s with a casting speed increasing from 1.0 m/min to 1.2 m/min, which intensified the meniscus turbulence. However, the increase in the port angle and the depth of the submerged entry nozzle (SEN) effectively reduced the maximum surface velocity to 0.238 m/s and 0.243 m/s, respectively, with a simultaneous improvement in the slag–steel interface temperature. Through MATLAB (version 2023b)-based reverse optimization combined with critical velocity analysis, the optimal mold slag properties were determined to be 2800 kg/m³ for the density, 4.756 × 10⁻⁶ m²/s for the kinematic viscosity, and 0.01 N/m for the interfacial tension. This systematic approach provides theoretical guidance for process optimization and slag design enhancement in industrial production. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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13 pages, 3976 KiB

Open AccessArticle

Streamlining First-Order Reversal Curves Analysis of Molecular Magnetism Bistability Using a Calorimetric Approach

by Diana Plesca, Cristian Enachescu, Radu Tanasa, Alexandru Stancu, Denis Morineau and Marie-Laure Boillot

Materials 2025, 18(14), 3413; https://doi.org/10.3390/ma18143413 - 21 Jul 2025

Viewed by 249

Abstract

We present an alternative to the classical SQUID magnetometric measurements for the First-Order Reversal Curve (FORC) diagram approach by employing differential scanning calorimetry (DSC) experiments. After discussing the main results, the advantages and limitations of the magnetometric FORCs, we introduce the calorimetric method. [...] Read more.

We present an alternative to the classical SQUID magnetometric measurements for the First-Order Reversal Curve (FORC) diagram approach by employing differential scanning calorimetry (DSC) experiments. After discussing the main results, the advantages and limitations of the magnetometric FORCs, we introduce the calorimetric method. We argue that, while the results are comparable to those obtained via magnetometry, the calorimetric method not only significantly simplifies the required mathematical computations but also detects subtle or overlapping phase transitions that might be hard to distinguish magnetically. The methodology is illustrated through both experimental data and mean-field simulations. Full article

(This article belongs to the Special Issue Nanosized and Nanostructured Magnetic Materials: Experimental, Theoretical, and Computational Investigations)

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9 pages, 4992 KiB

Open AccessCommunication

Corrosion Behavior of 347H Stainless Steel in NaCl-KCl-MgCl₂ Molten Salt: Vapor, Liquid, and Interface Comparison

by Zhiwen Liu, Huigai Li, Yang Wang, Yanjie Peng, Luyan Sun and Jianping Liang

Materials 2025, 18(14), 3412; https://doi.org/10.3390/ma18143412 - 21 Jul 2025

Viewed by 249

Abstract

The suitability of 347H stainless steel (SS347H) for chloride salt environments is critical in selecting materials for next-generation concentrated solar power (CSP) systems. This study investigated the corrosion behavior of SS347H in a ton-scale purification system with continuously flowing chloride salt under three [...] Read more.

The suitability of 347H stainless steel (SS347H) for chloride salt environments is critical in selecting materials for next-generation concentrated solar power (CSP) systems. This study investigated the corrosion behavior of SS347H in a ton-scale purification system with continuously flowing chloride salt under three conditions: exposure to NaCl-KCl-MgCl₂ molten salt vapor, immersion in molten salt, and at the molten salt surface interface. Results revealed that corrosion was most severe in the molten salt vapor, where HCl steam facilitated Cl⁻ reactions with Fe and Cr in the metal, causing dissolution and forming deep corrosion pits. At the interface, liquid Mg triggered displacement reactions with Fe²⁺/Cr²⁺ ions in the salt, depositing Fe and Cr onto the surface, which reduced corrosion intensity. Within the molten salt, Mg’s purification effect minimized impurity-induced corrosion, resulting in the least damage. In all cases, the primary corrosion mechanism involves the dissolution of Fe and Cr, with the formation of minor MgO. These insights provide valuable guidance for applying 347H stainless steel in chloride salt environments. Full article

(This article belongs to the Special Issue Microstructure, Mechanical and Corrosion Properties of Metals, Alloys, and Composite Materials)

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39 pages, 7187 KiB

Open AccessReview

Surface Coatings on Biomedical Magnesium Alloys

by Jiapeng Ren, Zhenyu Zhao, Hua Li, Dongsheng Wang, Cijun Shuai and Youwen Yang

Materials 2025, 18(14), 3411; https://doi.org/10.3390/ma18143411 - 21 Jul 2025

Viewed by 415

Abstract

Magnesium (Mg) alloys have demonstrated tremendous potential in biomedical applications, emerging as promising metallic biomaterials due to their biocompatibility, degradability, and favorable mechanical properties. However, their practical implementation faces significant limitations stemming from mechanical performance degradation and premature fracture failure caused by complex [...] Read more.

Magnesium (Mg) alloys have demonstrated tremendous potential in biomedical applications, emerging as promising metallic biomaterials due to their biocompatibility, degradability, and favorable mechanical properties. However, their practical implementation faces significant limitations stemming from mechanical performance degradation and premature fracture failure caused by complex physiological interactions, including flow erosion, corrosion fatigue, stress coupling effects, and dynamic wear under bodily conditions. Surface coating technology has been recognized as an effective strategy to prevent direct contact between magnesium substrates and corrosive media. This review systematically examines the fundamental degradation mechanisms of magnesium alloys in both vivo and vitro environments, presents recent advances in surface modification coatings for magnesium alloys, and critically analyses the interaction mechanisms between modified layers and electrolyte solutions. Special emphasis is placed on revealing the formation mechanisms, structural characteristics, and fracture behaviors of conversion coatings. Furthermore, the study discusses the current challenges in biomedical surface modification of magnesium alloys, proposes potential solutions to enhance their clinical applicability, and outlines future research directions to fully exploit the development potential of these advanced biomaterials. Full article

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

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22 pages, 29514 KiB

Open AccessArticle

Desert Sand in Alkali-Activated Fly Ash–Slag Mortar: Fluidity, Mechanical Properties, and Microstructure

by Wei Wang, Di Li, Duotian Xia, Ruilin Chen and Jianjun Cheng

Materials 2025, 18(14), 3410; https://doi.org/10.3390/ma18143410 - 21 Jul 2025

Viewed by 376

Abstract

The role and performance of desert sand in alkali-activated mortar remain insufficiently understood. To address this knowledge gap, this study systematically investigates the fluidity, mechanical properties, and microscopic morphology of alkali-activated mortar with varying desert sand substitution rates (DSRR, 0–100%). The key findings [...] Read more.

The role and performance of desert sand in alkali-activated mortar remain insufficiently understood. To address this knowledge gap, this study systematically investigates the fluidity, mechanical properties, and microscopic morphology of alkali-activated mortar with varying desert sand substitution rates (DSRR, 0–100%). The key findings reveal that a low DSRR (10–20%) enhances mortar fluidity and reduces drying shrinkage, though at the cost of reduced compressive strength. At 40% DSRR, the mortar exhibits elevated porosity (12.3%) and diminished compressive strength (63 MPa). Notably, complete substitution (100% DSRR) yields a well-structured matrix with optimized pore distribution, characterized by abundant gel micropores, and achieves a compressive strength of 76 MPa. These results demonstrate that desert sand can fully replace river sand in alkali-activated mortar formulations without compromising performance. Microstructural analysis confirms that desert sand actively participates in the alkali activation process. Specifically, the increased Ca²⁺ content facilitates the transformation of amorphous gels into crystalline phases. It also found that desert sand could make the fly ash more soluble, affecting the alkali activation reaction. Full article

(This article belongs to the Special Issue Research on Alkali-Activated Materials (Second Edition))

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15 pages, 3175 KiB

Open AccessArticle

Suppressing the Phase Transformation in Cubic Prussian Blue Analogues via a High-Entropy Strategy for Efficient Zinc-Ion Storage

by Hongwei Huang, Haojun Liu, Yang Wang, Yi Li and Qian Li

Materials 2025, 18(14), 3409; https://doi.org/10.3390/ma18143409 - 21 Jul 2025

Viewed by 289

Abstract

Prussian blue analogs (PBAs) are widely recognized as promising candidates for aqueous zinc-ion batteries (AZIBs) due to their stable three-dimensional framework structure. However, their further development is limited by their low specific capacity and unsatisfactory cycling performance, primarily caused by phase transformation during [...] Read more.

Prussian blue analogs (PBAs) are widely recognized as promising candidates for aqueous zinc-ion batteries (AZIBs) due to their stable three-dimensional framework structure. However, their further development is limited by their low specific capacity and unsatisfactory cycling performance, primarily caused by phase transformation during charge–discharge cycles. Herein, we employed a high-entropy strategy to introduce five different metal elements (Fe, Co, Ni, Mn, and Cu) into the nitrogen–coordinated M_a sites of PBAs, forming a high-entropy Prussian blue analog (HEPBA). By leveraging the cocktail effect of the high-entropy strategy, the phase transformation in the HEPBA was significantly suppressed. Consequently, the HEPBA as an AZIB cathode delivered a high reversible specific capacity of 132.1 mAh g⁻¹ at 0.1 A g⁻¹, and showed exceptional cycling stability with 84.7% capacity retention after 600 cycles at 0.5 A g⁻¹. This work provides innovative insights into the rational design of advanced cathode materials for AZIBs. Full article

(This article belongs to the Special Issue Optimization of Electrode Materials for Zinc Ion Batteries)

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20 pages, 10098 KiB

Open AccessArticle

Alkali-Activated Dredged-Sediment-Based Fluidized Solidified Soil: Early-Age Engineering Performance and Microstructural Mechanisms

by Qunchao Ma, Kangyu Wang, Qiang Li and Yuting Zhang

Materials 2025, 18(14), 3408; https://doi.org/10.3390/ma18143408 - 21 Jul 2025

Viewed by 278

Abstract

Fluidized solidified soil (FSS) has emerged as a promising material for marine pile scour remediation, yet its limited construction window and vulnerability to hydraulic erosion before sufficient curing constrain its broader application. This study systematically evaluates FSS formulations based on dredged sediment, cement [...] Read more.

Fluidized solidified soil (FSS) has emerged as a promising material for marine pile scour remediation, yet its limited construction window and vulnerability to hydraulic erosion before sufficient curing constrain its broader application. This study systematically evaluates FSS formulations based on dredged sediment, cement partially replaced by silica fume (i.e., 0%, 4%, 8%, and 12%), and quicklime activation under three water–solid ratios (WSR, i.e., 0.525, 0.55, and 0.575). Experimental assessments included flowability tests, unconfined compressive strength, direct shear tests, and microstructural analysis via XRD and SEM. The results indicate that SF substitution significantly mitigates flowability loss during the 90–120 min interval, thereby extending the operational period. Moreover, the greatest enhancement in mechanical performance was achieved at an 8% SF replacement: at WSR = 0.55, the 3-day UCS increased by 22.78%, while the 7-day cohesion and internal friction angle rose by 13.97% and 2.59%, respectively. Microscopic analyses also confirmed that SF’s pozzolanic reaction generated additional C-S-H gel. However, the SF substitution exhibits a pronounced threshold effect, with levels above 8% introducing unreacted particles that disrupt the cementitious network. These results underscore the critical balance between flowability and early-age strength for stable marine pile scour repair, with WSR = 0.525 and 8% SF substitution identified as the optimal mix. Full article

(This article belongs to the Special Issue Building a Sustainable Future: Latest Research on the Recovery of Solid Waste for Construction and Building Materials)

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12 pages, 4677 KiB

Open AccessArticle

Lap Welding of Nickel-Plated Steel and Copper Sheets Using Coaxial Laser Beams

by Kuan-Wei Su, Yi-Hsuan Chen, Hung-Yang Chu and Ren-Kae Shiue

Materials 2025, 18(14), 3407; https://doi.org/10.3390/ma18143407 - 21 Jul 2025

Viewed by 257

Abstract

The laser heterogeneous lap welding of nickel-plated steel and Cu sheets has been investigated in this study. The YAG (Yttrium-Aluminum-Garnet) laser beam only penetrates the upper Ni-plated steel sheet and cannot weld the bottom Cu sheet due to the low absorption coefficient of [...] Read more.

The laser heterogeneous lap welding of nickel-plated steel and Cu sheets has been investigated in this study. The YAG (Yttrium-Aluminum-Garnet) laser beam only penetrates the upper Ni-plated steel sheet and cannot weld the bottom Cu sheet due to the low absorption coefficient of the YAG laser beam. Incorporating a blue-light and fiber laser into the coaxial laser beam significantly improves the quality of the weld fusion zone. The fiber laser beam can penetrate the upper nickel-plated steel sheet, and the blue-light laser beam can melt the bottom copper sheet. Introducing the blue-light laser to the coaxial laser beams overcomes the low reflectivity of the bottom copper sheet. The fiber/blue-light coaxial laser continuous welding can achieve the best integrity and defect-free welding. It shows potential in the mass production of the next generation of lithium batteries. Full article

(This article belongs to the Special Issue Fusion Bonding/Welding of Metal and Non-Metallic Materials)

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28 pages, 5939 KiB

Open AccessArticle

Buckling Performance of Prefabricated Light-Gauge Steel Frame Materials Under Combined Random Defects During Construction: A CRITIC-Based Analysis

by Gang Yao, Ting Lei, Yang Yang and Mingtao Zhu

Materials 2025, 18(14), 3406; https://doi.org/10.3390/ma18143406 - 21 Jul 2025

Viewed by 295

Abstract

Light-gauge steel frame (LGSF) materials are inherently susceptible to stochastic imperfections arising from their design, manufacturing, and erection. These defects can compromise operational integrity and adversely impact structural stability, especially during the construction period. Consequently, a thorough investigation into the buckling characteristics of [...] Read more.

Light-gauge steel frame (LGSF) materials are inherently susceptible to stochastic imperfections arising from their design, manufacturing, and erection. These defects can compromise operational integrity and adversely impact structural stability, especially during the construction period. Consequently, a thorough investigation into the buckling characteristics of LGSF materials with such imperfections is imperative. Conventional stochastic probabilistic methods, such as Monte Carlo simulations, often fail to fully capture intrinsic material and complex structural properties, leading to discrepancies between computational predictions and actual behavior. To address these limitations, this study introduces an innovative model using the Criteria Importance Through Intercriteria Correlation (CRITIC) method to assess LGSF materials under combined defects scenarios. The CRITIC method systematically evaluates various buckling modes in LGSFs under combined defects to identify the most detrimental modal combination, representing the most unfavorable scenario. Rigorous finite element analysis is then performed on the LGSF model based on this critical scenario. Compared to conventional approaches, the proposed CRITIC-based combined defects analysis model predicts a 0%~5% reduction in the critical load factor and a 1%~3% increase in ultimate displacement at control nodes. These findings indicate that the CRITIC-based method yields a more critical combination of buckling modes, thereby enhancing the reliability and safety of the simulation results. Furthermore, this research demonstrates that, for LGSF materials, the common assumption that the first-order buckling mode is inherently the most deleterious failure pattern is inaccurate. Full article

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

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20 pages, 6191 KiB

Open AccessArticle

Functional Assessment of Microplasma-Sprayed Hydroxyapatite-Zirconium Bilayer Coatings: Mechanical and Biological Perspectives

by Sergii Voinarovych, Serhiy Maksimov, Sergii Kaliuzhnyi, Oleksandr Kyslytsia, Yuliya Safarova (Yantsen) and Darya Alontseva

Materials 2025, 18(14), 3405; https://doi.org/10.3390/ma18143405 - 21 Jul 2025

Viewed by 232

Abstract

Hydroxyapatite (HA) has become a widely used material for bone grafting and surface modification of titanium-based orthopedic implants due to its excellent biocompatibility. Among various coating techniques, microplasma spraying (MPS) has gained significant industrial relevance. However, the clinical success of HA coatings also [...] Read more.

Hydroxyapatite (HA) has become a widely used material for bone grafting and surface modification of titanium-based orthopedic implants due to its excellent biocompatibility. Among various coating techniques, microplasma spraying (MPS) has gained significant industrial relevance. However, the clinical success of HA coatings also depends on their adhesion to the implant substrate. Achieving durable fixation and reliable biological integration of orthopedic implants remains a major challenge due to insufficient coating adhesion and limited osseointegration. This study addresses challenges in dental and orthopedic implantology by evaluating the microstructure, mechanical properties, and biological behavior of bilayer coatings composed of a zirconium (Zr) sublayer and an HA top layer, applied via MPS onto titanium alloy. Surface roughness, porosity, and adhesion were characterized, and pull-off and shear tests were used to assess mechanical performance. In vitro biocompatibility was tested using rat mesenchymal stem cells (MSCs) to model osteointegration. The results showed that the MPS-fabricated Zr–HA bilayer coatings achieved a pull-off strength of 28.0 ± 4.2 MPa and a shear strength of 32.3 ± 3.2 MPa, exceeding standard requirements. Biologically, the HA top layer promoted a 45% increase in MSC proliferation over three days compared to the uncoated titanium substrate. Antibacterial testing also revealed suppression of E. coli growth after 14 h. These findings support the potential of MPS-applied Zr-HA coatings to enhance both the mechanical integrity and biological performance of titanium-based orthopedic implants. Full article

(This article belongs to the Special Issue Biomechanical and Metallurgical Behavior of Endodontic and Restorative Materials)

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16 pages, 2312 KiB

Open AccessArticle

A Multi-Response Investigation of Abrasive Waterjet Machining Parameters on the Surface Integrity of Twinning-Induced Plasticity (TWIP) Steel

by Onur Cavusoglu

Materials 2025, 18(14), 3404; https://doi.org/10.3390/ma18143404 - 21 Jul 2025

Viewed by 312

Abstract

Twinning-induced plasticity (TWIP) steels represent a significant development in automotive steel production, characterized by advanced strength and ductility properties. The present study empirically investigated the effects of process parameters on the cutting process and surface quality of TWIP980 steel sheet by abrasive water [...] Read more.

Twinning-induced plasticity (TWIP) steels represent a significant development in automotive steel production, characterized by advanced strength and ductility properties. The present study empirically investigated the effects of process parameters on the cutting process and surface quality of TWIP980 steel sheet by abrasive water jet (AWJ) cutting. The cutting experiments were conducted on 1.4 mm thick sheet metal using four different traverse speeds (50, 100, 200, and 400 mm/min) and four different water jet pressures (1500, 2000, 2500, and 3000 bar). Two different abrasive flow rates (300 and 600 g/min) were also utilized. The cut surfaces were characterized in three dimensions with an optical profilometer. The parameters of surface roughness, kerf width, taper angle, and material removal rate (MRR) were determined. Furthermore, microhardness measurements were conducted on the cut surfaces. The optimal surface quality and geometrical accuracy were achieved by applying a combination of parameters, including 3000 bar of pressure, a traverse rate of 400 mm/min, and an abrasive flow rate of 600 g/min. Concurrently, an effective cutting performance with increased MRR and reduced taper angles was achieved under these conditions. The observed increase in microhardness with increasing pressure is attributable to a hardening effect resulting from local plastic deformation. Full article

(This article belongs to the Special Issue Progressive Technologies and Materials in Mechanical and Materials Engineering)

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12 pages, 2107 KiB

Open AccessArticle

Assessment of Diameter Stability in Morse Taper Dental Implants with Different Angulations After Abutment Connection

by Bruno Q. S. Cordeiro, Waldimir R. Carvalho, Edgard M. Fonseca, Aldir N. Machado, Bruna Ghiraldini, Michel A. D. Soares and Priscila L. Casado

Materials 2025, 18(14), 3403; https://doi.org/10.3390/ma18143403 - 21 Jul 2025

Viewed by 294

Abstract

Background: Modification of diameter stability after the abutment retention can result in a decrease in the applied torque or affect the peri-implant tissue, compromising the longevity of the treatment. Therefore, this study aimed to investigate how different connection angles (11.5° and 16.0°) at [...] Read more.

Background: Modification of diameter stability after the abutment retention can result in a decrease in the applied torque or affect the peri-implant tissue, compromising the longevity of the treatment. Therefore, this study aimed to investigate how different connection angles (11.5° and 16.0°) at the implant–abutment interface influence implant diameter stability under the manufacturer’s recommended torque. Methods: Eighty Morse cone-type implant specimens were divided into two groups, with different internal conicity angles: 11.5° (n = 40) and 16.0° (n = 40). Implants varied in diameter (mm): 3.5, 3.8, 4.5, and 5.0. Initial measurements of the implants’ external diameter were carried out. After these measurements, all implants received the abutment installation, and a final measurement of the external implant diameter was performed. Results: Considering the comparative analysis between the final and initial diameters, a non-significant increase in diameter, in the cervical implant region, after torque on the abutment, was observed. The torque applied to the abutments did not produce deformations in the cervical area of Morse taper implants. Conclusions: The torque applied to the abutment screw in implants with a Morse taper connection does not cause deformation in the cervical area of the implant body in implant with 11.5° and 16.0° conicity angles. Full article

(This article belongs to the Section Biomaterials)

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17 pages, 2341 KiB

Open AccessSystematic Review

Influence of Process and Material Factors on the Quality of Machine Processing of Laminated Particleboard

by Łukasz Adamik, Radosław Auriga and Piotr Borysiuk

Materials 2025, 18(14), 3402; https://doi.org/10.3390/ma18143402 - 21 Jul 2025

Viewed by 327

Abstract

Next to solid wood, laminated particleboard is the most widely used wood-based material in the furniture industry. Ensuring the high quality of the laminate surface after machining is of critical importance for furniture manufacturers, particularly prior to the edge banding process, as this [...] Read more.

Next to solid wood, laminated particleboard is the most widely used wood-based material in the furniture industry. Ensuring the high quality of the laminate surface after machining is of critical importance for furniture manufacturers, particularly prior to the edge banding process, as this process significantly influences the final aesthetic and functional quality of panel elements. The objective of this review article is to gather and evaluate the current state of knowledge regarding the influence of machining process parameters and the physical and mechanical properties of laminated particleboard on machining quality. Particular emphasis is placed on the occurrence of laminate damage, commonly referred to as delamination, a prevalent defect in the furniture manufacturing sector. Both categories of influencing factors—process-related and material-related—are analyzed within the context of the three primary technological processes employed in the woodworking industry, namely drilling, cutting, and milling. The analysis revealed that a persistent research gap concerns the relationship between machining quality and material parameters, particularly in the case of milling—a process of critical importance in the furniture industry. Full article

(This article belongs to the Special Issue Advances in Biomass-Based Materials and Their Applications (2nd Edition))

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13 pages, 3335 KiB

Open AccessArticle

Metallization of 3D-Printed PET and PETG Samples with Different Filling Densities of the Inner Layers

by Sonya Petrova, Diana Lazarova, Mihaela Georgieva, Maria Petrova, Dimiter Dobrev and Dimitre Ditchev

Materials 2025, 18(14), 3401; https://doi.org/10.3390/ma18143401 - 20 Jul 2025

Viewed by 332

Abstract

The aim of the study was to develop a suitable pre-treatment (and more specifically, the etching operation) of 3D-printed PET and PETG samples with different filling densities of the inner layers for subsequent electroless metallization. The influence of temperature, etching time, and sodium [...] Read more.

The aim of the study was to develop a suitable pre-treatment (and more specifically, the etching operation) of 3D-printed PET and PETG samples with different filling densities of the inner layers for subsequent electroless metallization. The influence of temperature, etching time, and sodium hydroxide concentration in the etching solution on the deposition rate, adhesion, and composition of Ni-P coatings was determined. The studies show that a high temperature and concentration of the etching solution do not improve the properties of the coating. The etching not only plays an important role in improving adhesion but also affects the composition and thickness of the nickel layer. It was also established how the degree of filling densities of the inner layers affects the uniformity, penetration depth, and thickness of electrolessly deposited Cu and Ni-P coatings on 3D PETG samples. Full article

(This article belongs to the Special Issue 3D Printing Materials in Civil Engineering)

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13 pages, 1795 KiB

Open AccessArticle

Machine Learning-Based Prediction of Time Required to Reach the Melting Temperature of Metals in Domestic Microwaves Using Dimensionless Modeling and XGBoost

by Juan José Moreno Labella, Milagrosa González Fernández de Castro, Víctor Saiz Sevilla, Miguel Panizo Laiz and Yolanda Martín Álvarez

Materials 2025, 18(14), 3400; https://doi.org/10.3390/ma18143400 - 20 Jul 2025

Viewed by 298

Abstract

A novel and cost-effective methodology is introduced for the precise prediction of the melting time of metals and alloys in a 700 W domestic microwave oven, using a hybrid SiC–graphite susceptor to ensure efficient heating without direct interaction with microwaves. The study includes [...] Read more.

A novel and cost-effective methodology is introduced for the precise prediction of the melting time of metals and alloys in a 700 W domestic microwave oven, using a hybrid SiC–graphite susceptor to ensure efficient heating without direct interaction with microwaves. The study includes experimental trials with multiple alloys (Sn–Bi, Zn, Zamak, and Al–Si, among others) and variable masses, whose results made it possible to construct a dimensionless model, trained with XGBoost on easily measurable thermophysical properties (specific heat, density, thermal conductivity, mass, and melting temperature). The model achieves high accuracy, with a relative error below 5%, and metrics of MAE = 4.8 s, RMSE = 6.1 s, and R² = 0.9996. The generalization of the model to different microwave powers (600–1100 W) is also validated through analytical adjustment, without the need for additional experiments. The proposal is implemented as a Python application with a graphical interface, suitable for any academic or teaching laboratory, and its performance is compared with classical models. This approach effectively contributes to the democratization of thermal testing of metals in educational and research settings with limited resources, providing thermodynamic rigor and advanced artificial intelligence tools. Full article

(This article belongs to the Section Advanced Materials Characterization)

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12 pages, 7486 KiB

Open AccessArticle

Dissolution and Early Hydration Interaction of C₃A-C₄AF Polyphase in Water and Aqueous Sulfate Solutions

by Shaoxiong Ye and Pan Feng

Materials 2025, 18(14), 3399; https://doi.org/10.3390/ma18143399 - 20 Jul 2025

Viewed by 327

Abstract

The concurrent dissolution and early hydration of tricalcium aluminate (C₃A) and tetracalcium aluminoferrite (C₄AF) critically govern early-stage reaction dynamics in Portland cement systems. However, their mutual kinetic interactions during reaction, particularly sulfate-dependent modulation mechanisms, remain poorly understood. Using in-situ [...] Read more.

The concurrent dissolution and early hydration of tricalcium aluminate (C₃A) and tetracalcium aluminoferrite (C₄AF) critically govern early-stage reaction dynamics in Portland cement systems. However, their mutual kinetic interactions during reaction, particularly sulfate-dependent modulation mechanisms, remain poorly understood. Using in-situ digital holographic microscopy (DHM), this study resolved their interaction mechanisms during co-dissolution in aqueous and sulfate-bearing environments. Results reveal asymmetric modulation: while C₄AF’s dissolution exhibited limited sensitivity to C₃A’s presence, C₃A’s kinetics were profoundly altered by C₄AF through sulfate-concentration-dependent pathways, which originated from two competing C₄AF-mediated mechanisms: (1) suppression via common-ion effects, and (2) acceleration through competitive sulfate species adsorption. These mechanistic insights would provide a roadmap for optimizing cementitious materials through optimized reaction pathways. Full article

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

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20 pages, 3980 KiB

Open AccessArticle

Laboratory and Full-Scale Tests of Modern Chimney Casings Based on Lightweight Perlite Concrete with Hydrophobic Admixtures

by Arkadiusz Mordak, Krzysztof Drozdzol, Damian Beben and Pawel Jarzynski

Materials 2025, 18(14), 3398; https://doi.org/10.3390/ma18143398 - 20 Jul 2025

Viewed by 265

Abstract

Currently, chimney technology is looking for new materials with improved thermal insulation properties and, at the same time, adequate durability. The use of concretes based on lightweight aggregates, such as expanded perlite, is capable of meeting such a challenge, provided that the composition [...] Read more.

Currently, chimney technology is looking for new materials with improved thermal insulation properties and, at the same time, adequate durability. The use of concretes based on lightweight aggregates, such as expanded perlite, is capable of meeting such a challenge, provided that the composition of the concrete mixes is appropriately modified. The main research challenge when designing chimney system casing elements lies in ensuring adequate resistance to moisture penetration (maximum water absorption of 25%), while achieving the lowest possible bulk density (below 1000 kg/m³), sufficient compressive strength (minimum 3.5 MPa), and capillary water uptake not exceeding 0.6%. In the present research, laboratory tests were conducted to improve the fundamental technical properties of lightweight perlite-based concrete to meet the aforementioned requirements. Laboratory tests of perlite concrete were carried out by adding eight chemical admixtures with a hydrophobic effect and the obtained results were compared with a reference concrete (without admixtures). However, the positive results obtained under laboratory conditions were not confirmed under actual production conditions. Therefore, further tests were conducted on chimney casings taken directly from the production line. Subsequent chemical admixtures with a hydrophobic effect, based on silane/siloxane water emulsions, were applied to determine the concrete mix’s optimal composition. The results of the tests carried out on perlite concrete chimney casings from the production line confirm the effectiveness of the applied chemical admixtures with a hydrophobic effect in improving the moisture resistance. This was further supported by the outcomes of the so-called ‘drop test’ and capillary uptake test, with the suitable bulk density and compressive strength being maintained. Full article

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

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17 pages, 2870 KiB

Open AccessArticle

Influence of Magnetorheological Finishing on Surface Topography and Functional Performance of Shoulder Joint Cap Surface

by Manpreet Singh, Gagandeep Singh, Riyad Abu-Malouh, Sumika Chauhan and Govind Vashishtha

Materials 2025, 18(14), 3397; https://doi.org/10.3390/ma18143397 - 20 Jul 2025

Viewed by 356

Abstract

The surface quality of biomedical implants, such as shoulder joint caps, plays a critical role in their performance, longevity, and biocompatibility. Most biomedical shoulder joints fail to reach their optimal functionality when finished through conventional techniques like grinding and lapping due to their [...] Read more.

The surface quality of biomedical implants, such as shoulder joint caps, plays a critical role in their performance, longevity, and biocompatibility. Most biomedical shoulder joints fail to reach their optimal functionality when finished through conventional techniques like grinding and lapping due to their inability to achieve nanometer-grade smoothness, which results in greater wear and friction along with potential failure. The advanced magnetorheological finishing (MRF) approach provides enhanced surface quality through specific dimensional control material removal. This research evaluates how MRF treatment affects the surface roughness performance and microhardness properties and wear resistance behavior of cobalt–chromium alloy shoulder joint caps which have biocompatible qualities. The study implements a magnetorheological finishing system built with an electromagnetic tool to achieve the surface roughness improvements from 0.35 µm to 0.03 µm. The microhardness measurements show that MRF applications lead to a rise from HV 510 to HV 560 which boosts the wear protection of samples. After MRF finishing, the coefficient of friction demonstrates a decrease from 0.12 to 0.06 which proves improved tribological properties of these implants. The results show that MRF technology delivers superior benefits for biomedical use as it extends implant life span and decreases medical complications leading to better patient health outcomes. The purposeful evaluation of finishing techniques and their effects on implant functionality demonstrates MRF is an advanced technology for upcoming orthopedic implants while yielding high precision and enhanced durability and functional output. Full article

(This article belongs to the Special Issue Computational and Experimental Modeling of Interfaces and Joints in Advanced Materials)

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17 pages, 4491 KiB

Open AccessArticle

Effect of Synthesized C-S-H Nanoparticles on the Early Hydration and Microstructure of Cement

by Yoojung Hwang, Suji Woo and Young-Cheol Choi

Materials 2025, 18(14), 3396; https://doi.org/10.3390/ma18143396 - 20 Jul 2025

Viewed by 357

Abstract

Ground granulated blast-furnace slag (GGBS), a waste product generated during steel production, can be added as a substitute for cement in concrete to mitigate the environmental impact of the cement and steel industries. However, the use of GGBS is limited because it decreases [...] Read more.

Ground granulated blast-furnace slag (GGBS), a waste product generated during steel production, can be added as a substitute for cement in concrete to mitigate the environmental impact of the cement and steel industries. However, the use of GGBS is limited because it decreases the early strength development of cement or concrete. This study evaluated the performance of incorporating synthesized C-S-H nanoparticles to enhance the compressive strength, early hydration, and microstructure of cement composite. The synthesized C-S-H nanoparticles were produced at standard atmospheric pressure and room temperature. Heat of hydration, X-ray diffraction, and thermogravimetric analyses were conducted to investigate the hydration and mechanical properties of the cement containing the C-S-H nanoparticles. Further, mercury intrusion porosimetry was conducted to examine the pore structures. The experimental finding demonstrated that adding C-S-H nanoparticles accelerated the early hydration progress in the cement composites, thereby increasing their initial compressive strength. Full article

(This article belongs to the Special Issue Concretes and Cement-Based Composites: Additives/Admixtures, Hydration Process and Durability Research (3rd Edition))

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18 pages, 4106 KiB

Open AccessArticle

Assessment of Ammonia Adsorption Capacity on Activated Banana Peel Biochars

by Katarzyna Jedynak and Barbara Charmas

Materials 2025, 18(14), 3395; https://doi.org/10.3390/ma18143395 - 20 Jul 2025

Viewed by 383

Abstract

This paper presents the assessment of the possibility of ammonia adsorption on biochars from banana peels, chemically activated with potassium hydroxide (KOH) at different temperatures. The obtained materials were characterized in detail using a number of analytical techniques, including nitrogen adsorption (BET), scanning [...] Read more.

This paper presents the assessment of the possibility of ammonia adsorption on biochars from banana peels, chemically activated with potassium hydroxide (KOH) at different temperatures. The obtained materials were characterized in detail using a number of analytical techniques, including nitrogen adsorption (BET), scanning electron microscopy (SEM), elemental analysis (CHNS), thermal analysis (TG, DTG, DTA), Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, Boehm titration method and biochar surface pH. They revealed a largely developed microporous structure and a large specific surface area, ranging from 1134 to 2332 m² g⁻¹. The adsorption tests against ammonia in the gas phase showed a large adsorption capacity of the materials, up to 5.94 mmol g⁻¹ at 0 °C and 3.83 mmol g⁻¹ at 20 °C. The adsorption properties of the obtained biochars were confirmed to be significantly influenced by the surface chemistry (presence of the acidic functional groups). The research results indicate that the waste-based biomass, such as banana peels, can be an ecological and economical raw material for the production of highly effective adsorbents, useful in the removal of ammonia and other toxic gases polluting the environment. Full article

(This article belongs to the Section Porous Materials)

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23 pages, 4453 KiB

Open AccessArticle

Nonlinear Elasticity and Damage Prediction in Automated Fiber Placement Composites via Nested Micromechanics

by Hadas Hochster, Gal Raanan, Eyal Tiosano, Yoav Harari, Golan Michaeli, Yonatan Rotbaum and Rami Haj-Ali

Materials 2025, 18(14), 3394; https://doi.org/10.3390/ma18143394 - 19 Jul 2025

Viewed by 333

Abstract

Automated fiber placement (AFP) composites exhibit complex mechanical behaviors due to manufacturing-induced mesostructural variations, including resin-rich regions and tow gaps that significantly influence both local stress distributions and global material responses. This study presents a hierarchically nested modeling framework based on the Parametric [...] Read more.

Automated fiber placement (AFP) composites exhibit complex mechanical behaviors due to manufacturing-induced mesostructural variations, including resin-rich regions and tow gaps that significantly influence both local stress distributions and global material responses. This study presents a hierarchically nested modeling framework based on the Parametric High-Fidelity Generalized Method of Cells (PHFGMC) to predict the effective elastic properties and nonlinear mechanical response of AFP composites. The PHFGMC model integrates micro- and meso-scale analyses using representative volume elements (RVEs) derived from micrographs of AFP composite laminates to capture these manufacturing-induced characteristics. Multiple RVE configurations with varied gap patterns are analyzed to quantify the influence of mesostructural features on global stress–strain response. Predictions for linear and nonlinear elastic behaviors are validated against experimental results from carbon fiber/epoxy AFP specimens, demonstrating good quantitative agreement with measured responses. A cohesive extension of the PHFGMC framework further captures damage initiation and crack propagation under transverse tensile loading, revealing failure mechanisms specifically associated with tow gaps and resin-rich areas. By systematically accounting for manufacturing-induced variability through detailed RVE modeling, the nested PHFGMC framework enables the accurate prediction of global mechanical performance and localized behavior, providing a robust computational tool for optimizing AFP composite design in aerospace and other high-performance applications. Full article

(This article belongs to the Special Issue Mechanical Behaviour of Advanced Metal and Composite Materials)

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Materials, Volume 18, Issue 14 (July-2 2025) – 215 articles

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