Materials

17 pages, 1362 KiB

Open AccessArticle

Understanding the Non-Steady Electrochemical Mechanisms of the Stress Corrosion Cracking of X70 Pipeline Steel in a Marine Environment

by Bo Xu, Baozhuang Sun, Yang Dai, Fei Xie, Feng Huang, Zhiyong Liu and Xiaogang Li

Materials 2025, 18(9), 2073; https://doi.org/10.3390/ma18092073 (registering DOI) - 30 Apr 2025

Abstract

In this study, a non-stationary electrochemical model was verified to be equally applicable to X70 pipeline steel under polarization potential in a marine environment, and the mechanism of stress corrosion cracking (SCC) was revealed. A quick SCC evaluation model for X70 pipeline steel [...] Read more.

In this study, a non-stationary electrochemical model was verified to be equally applicable to X70 pipeline steel under polarization potential in a marine environment, and the mechanism of stress corrosion cracking (SCC) was revealed. A quick SCC evaluation model for X70 pipeline steel in a marine environment was established. The model only requires electrochemical tests and a small number of slow strain rate tests to obtain the stress corrosion susceptibility distribution of pipeline steel across the whole potential range. The model is applicable to the marine environment and is characterized by its easy operation and accurate results. Full article

(This article belongs to the Section Corrosion)

16 pages, 1492 KiB

Open AccessArticle

Influence of Zn²⁺ Concentration on Ceramic Coatings for Corrosion Protection of Magnesium-Lithium Alloys

by Yifei Wang, Chunming Liu, Hongzhan Li and Zhen Zhang

Materials 2025, 18(9), 2072; https://doi.org/10.3390/ma18092072 (registering DOI) - 30 Apr 2025

Abstract

This study investigates the enhancement of corrosion resistance in magnesium-lithium alloys through plasma electrolytic oxidation (PEO) coatings incorporating ZnF₂ via in situ synthesis. By adjusting Zn²⁺ concentrations (4–16 g/L) in a zirconium salt-based electrolyte, ceramic coatings with tailored ZnF₂ [...] Read more.

This study investigates the enhancement of corrosion resistance in magnesium-lithium alloys through plasma electrolytic oxidation (PEO) coatings incorporating ZnF₂ via in situ synthesis. By adjusting Zn²⁺ concentrations (4–16 g/L) in a zirconium salt-based electrolyte, ceramic coatings with tailored ZnF₂ content, thickness, and porosity were fabricated. The optimal Zn²⁺ concentration of 12 g/L yielded a ZnF₂-rich coating with isolated pores and enhanced densification (inner layer resistance R_i= 3.01 × 10⁴ Ω⋅cm²), achieving a corrosion current density (i_corr) of 4.42 × 10⁻⁸ A/cm² and polarization resistance (Rp) of 8.5 × 10⁵ Ω⋅cm², representing a 354-fold improvement over untreated LA103Z. Higher Zn²⁺ concentrations (16 g/L) induced interconnected pores and ZnO formation, degrading corrosion resistance. Long-term immersion (168 h in 3.5 wt% NaCl) confirmed the durability of Zn₁₂ coatings (mass loss: 0.6 mg), while Zn₄ and Zn₁₆ coatings exhibited severe localized corrosion. The study demonstrates that balancing Zn²⁺ concentration optimizes ZnF₂ passivation and pore isolation, offering a scalable strategy for Mg-Li alloy protection in corrosive environments. Full article

13 pages, 6108 KiB

Open AccessArticle

Mechanical Performance Degradation of ECO EPDM Elastomers in Acidic Fuel Cell Environments

by Daniel Foltuț and Viorel-Aurel Șerban

Materials 2025, 18(9), 2071; https://doi.org/10.3390/ma18092071 (registering DOI) - 30 Apr 2025

Abstract

Sustainable ethylene propylene diene monomer (EPDM) elastomers are gaining traction as eco-friendly sealing materials in fuel cell applications. This study evaluates the mechanical degradation behavior of two ECO EPDM formulations—one reinforced with circular carbon black (CCB EPDM), and the other with recycled carbon [...] Read more.

Sustainable ethylene propylene diene monomer (EPDM) elastomers are gaining traction as eco-friendly sealing materials in fuel cell applications. This study evaluates the mechanical degradation behavior of two ECO EPDM formulations—one reinforced with circular carbon black (CCB EPDM), and the other with recycled carbon black (RCB EPDM)—under conditions representative of acidic fuel cell environments. The samples underwent thermal aging at 90 °C for 1000 h, and were immersed in aqueous H₂SO₄ solutions of varying concentrations (1 M, 0.1 M, and 0.001 M) for 1000 h at the same temperature. Gravimetric and volumetric swelling measurements revealed that RCB EPDM experienced significantly higher mass and volume uptake, particularly at intermediate acid concentration, indicating greater susceptibility to fluid ingress. Mechanical testing, including measurement of tensile strength, Shore A hardness, and IRHD microhardness, showed that while RCB EPDM exhibited higher initial strength, it degraded more severely under thermal and acidic exposure. SEM-EDS analysis revealed microstructural damage and compositional changes, with RCB EPDM displaying more pronounced oxidation and surface erosion. In contrast, CCB EPDM demonstrated greater retention of mechanical integrity, greater dimensional stability, and lower variability across aging conditions. These findings highlight the advantages of circular carbon black in enhancing the durability of ECO EPDM compounds in acidic and thermally dynamic fuel cell environments. Full article

(This article belongs to the Collection Materials and Technologies for Hydrogen and Fuel Cells)

17 pages, 520 KiB

Open AccessArticle

Innovative Materials as Micronutrient Carriers in Soybean Cultivation

by Marzena S. Brodowska, Mirosław Wyszkowski and Ryszard Grzesik

Materials 2025, 18(9), 2070; https://doi.org/10.3390/ma18092070 (registering DOI) - 30 Apr 2025

Abstract

Many of today’s innovative materials used to carry trace elements (TEs) are derived from chelates. Most of the materials used for this purpose have been produced on the basis of EDTA, which is not considered to be environmentally friendly due to its high [...] Read more.

Many of today’s innovative materials used to carry trace elements (TEs) are derived from chelates. Most of the materials used for this purpose have been produced on the basis of EDTA, which is not considered to be environmentally friendly due to its high persistence. Research is therefore being carried out to produce materials that do not pose an environmental risk. Therefore, a study was carried out to determine the effects of newly developed innovative materials with embedded biodegradable and environmentally safe chelates (IDHA—iminodisuccinic acid—and N-butyl-D-gluconamide ligands) containing copper, molybdenum and iron on the yield, biometric characteristics and chemical composition of soybean and selected soil properties. It is difficult to find publications on their effects in soybean cultivation. The greatest increase in soybean leaf greenness index (SPAD) was found after the addition of pure Salmag^® (Sal.^®). The effect of the chelates on the SPAD index was lower, with Sal.^® + Fe chelate having the greatest effect during the vegetative development stage and Cu chelate having the greatest effect during the flowering stage. Sal.^® + Cu, especially with Fe, accelerated pod and seed ripening in the last vegetative stage of soybean. Sal.^® + Cu had the most favourable impact on plant height, pure Sal.^® on the pod number per plant, Sal.^® + Fe on the seed number per pod, Sal.^® with Mo and Fe chelates on soybean seed yield, and pure Sal.^® on fresh weight remaining above-ground part yield, while pure Sal.^® and Sal.^® + Fe had the most favourable impact on dry weight aerial yield. The fertiliser materials (especially Sal.^® + Cu) generally increased the N content of the tested soybean organs and the Cu content of the other above-ground soybean parts (especially those containing chelates) and had an antagonistic effect on the Mg content of the soybean above-ground parts. Sal.^® + Cu also had a negative effect on the Fe content of other above-ground soybean parts. Sal.^® + Fe had a positive impact on the iron content, and Sal.^® + Mo had a positive impact on the molybdenum content of soybean. The applied fertilisers had little effect on the contents of Cu, Mo and Fe in the soil. There was only a significant increase in the Cu content of the soil after the addition of Sal.^® + Cu and a significantly smaller increase under the influence of Sal.^® without chelates, as well as an increase in the Mo content of the soil with Sal.^®. The present study confirms the beneficial impact of the novel materials with chelates. It has been demonstrated that the presence of materials containing Mo and, in particular, Cu has a considerable effect on the yield and quality characteristics of soybeans. Full article

(This article belongs to the Special Issue Sustainability, Circular Economy and Waste Recycling: Advances in Materials Research (2nd Edition))

13 pages, 3376 KiB

Open AccessArticle

Evaluation of Deformation and Antibacterial Properties of Dental Alginates Mixed with Silver Nanoparticles

by Mario A. Rivera-Cortés, Nereyda Niño-Martínez, Facundo Ruiz, Brianda Karina Félix-Sicairos and Gabriel-Alejandro Martínez-Castañón

Materials 2025, 18(9), 2069; https://doi.org/10.3390/ma18092069 (registering DOI) - 30 Apr 2025

Abstract

This study aimed to evaluate the effect of the incorporation of silver nanoparticles (AgNPs) of 5.57 nm size into dental alginates on their deformation and antimicrobial properties. Six experimental groups were prepared: 2 different alginates with 0.25 wt% AgNPs, 2 different alginates with [...] Read more.

This study aimed to evaluate the effect of the incorporation of silver nanoparticles (AgNPs) of 5.57 nm size into dental alginates on their deformation and antimicrobial properties. Six experimental groups were prepared: 2 different alginates with 0.25 wt% AgNPs, 2 different alginates with 0.5 wt% AgNPs (5.57 nm), and 2 unmodified control alginate groups. The presence of AgNPs was confirmed using X-ray diffraction analysis with a Bruker D8 Advance diffractometer. Antimicrobial activity was evaluated using the Kirby-Bauer disk diffusion method (direct contact) against E. coli and S. aureus cultures incubated on Mueller–Hinton (M-H) agar at 37 °C for 24 h. The results demonstrated that the addition of 0.25% and 0.5% AgNPs significantly enhanced the antimicrobial properties of alginate (p < 0.05), showing clear inhibition zones against the tested microorganisms. In terms of mechanical properties, AgNPs-modified samples exhibited improved elastic recovery compared to the control group (p > 0.05). These findings suggest that incorporating silver nanoparticles into alginates could enhance their antimicrobial properties without compromising the mechanical integrity required for dental applications. Full article

(This article belongs to the Special Issue Advanced Materials for Oral Application (3rd Edition))

13 pages, 985 KiB

Open AccessArticle

Macroscale Static Mechanical Behaviors of Cemented Sand Gravel Dams with Consideration of Construction Interfaces

by Qinghui Liu, Xinzhuo Xie, Long Qian, Xingwen Guo and Xin Cai

Materials 2025, 18(9), 2068; https://doi.org/10.3390/ma18092068 (registering DOI) - 30 Apr 2025

Abstract

In order to study the influence of construction interfaces on the safety of middle-low and 100-m cemented sand gravel (CSG) dams, direct shear tests of the construction interfaces with laying mortar and roughening under four different normal pressures are firstly conducted; shear stress–shear [...] Read more.

In order to study the influence of construction interfaces on the safety of middle-low and 100-m cemented sand gravel (CSG) dams, direct shear tests of the construction interfaces with laying mortar and roughening under four different normal pressures are firstly conducted; shear stress–shear displacement curves and interface parameters for the interface models are obtained. Then, finite element models are established using a modified Duncan–Chang constitutive model and a zero-thickness interface model. Displacements, stresses, and anti-sliding stability coefficients of the construction interfaces are obtained, load-bearing capacity is analyzed using the water bulk density overload method, and the obtained results are compared with those of the model without consideration of the construction interfaces. The results show that the obtained displacements and stresses become larger or remain constant when the construction interfaces are considered. The two interface treatment methods (laying mortar and roughening) meet the requirements of anti-sliding stability, and the load-bearing capacity of the construction interface with laying mortar is greater. This study reveals the influence of construction interfaces on the overall mechanical behaviors of the CSG dams and provides technical guidelines for the two construction interface treatments. Full article

(This article belongs to the Section Mechanics of Materials)

17 pages, 6330 KiB

Open AccessArticle

Hot Deformation Behavior and Constitutive Equation of TA15N Titanium Alloy

by Bo Huang, Yang Yu, Wenjun Ye and Songxiao Hui

Materials 2025, 18(9), 2067; https://doi.org/10.3390/ma18092067 (registering DOI) - 30 Apr 2025

Abstract

In order to accurately obtain the deformation characteristics and suitable thermal deformation conditions of TA15N titanium alloy and guide the design of deformation process parameters, a Gleeble 1500D was used to conduct hot compression tests on the thermal deformation behavior of a deformed [...] Read more.

In order to accurately obtain the deformation characteristics and suitable thermal deformation conditions of TA15N titanium alloy and guide the design of deformation process parameters, a Gleeble 1500D was used to conduct hot compression tests on the thermal deformation behavior of a deformed TA15N titanium alloy under the condition of a strain rate of 0.01–10 s⁻¹ and a deformation temperature of 850–1090 °C. The constitutive equations for the deformed TA15N titanium alloy based on the Arrhenius formula were developed, and the reliability of the constitutive equations was verified. A thermal processing map of the deformed TA15N titanium alloy was established by using the dynamic materials model (DMM). The research results show that the flow stress of the TA15N alloy decreased with an increase in deformation temperature and a decrease in strain rate. By utilizing electron backscattered diffraction (EBSD), the microstructural evolution and deformation process were analyzed. As the value of η decreased, dynamic recovery (DRV) gradually replaced dynamic recrystallization (DRX). This study supplies a relatively reliable processing interval for the new TA15N titanium alloy. Full article

(This article belongs to the Section Metals and Alloys)

18 pages, 3049 KiB

Open AccessArticle

Effect of the Peri-Annulated Dichalcogenide Bridge on the Bipolar Character of Naphthalimide Derivatives Used as Organic Electrode Materials

by Delyana Marinova, Lyuben Borislavov, Silva Stanchovska, Konstantin Konstantinov, Monika Mutovska, Stanimir Stoyanov, Yulian Zagranyarski, Yanislav Danchovski, Hristo Rasheev, Alia Tadjer and Radostina Stoyanova

Materials 2025, 18(9), 2066; https://doi.org/10.3390/ma18092066 (registering DOI) - 30 Apr 2025

Abstract

In recent years, bipolar organic electrode materials have gained recognition as competitive alternatives to inorganic materials due to their unique multielectron redox mechanism for energy storage. In this study, we examined the mechanism of redox reactions in naphthalimide (NI) derivatives when used as [...] Read more.

In recent years, bipolar organic electrode materials have gained recognition as competitive alternatives to inorganic materials due to their unique multielectron redox mechanism for energy storage. In this study, we examined the mechanism of redox reactions in naphthalimide (NI) derivatives when used as electrodes in lithium half-cells with ionic liquid electrolytes. The NI derivatives consist of three building fragments: an aromatic naphthalene core, N-alkylated imide unit, and a peri-dichalcogenide bridge. The integration of electrochemical and microscopic methods with DFT calculations facilitates the delineation of the role of each fragment in the oxidation and reduction reactions of NI derivatives. It is found that the peri-dichalcogenide bridge is mainly involved in the oxidation of NI derivatives above 3.9 V, the charge compensation being achieved by electrolyte TFSI⁻ counter-ions. The reduction of NI derivatives with two Li⁺ ions is mainly due to the participation of the chalcogenide bridge, while after interaction with the next two Li⁺ ions, the imide fragment and the naphthalene moiety contribute equally to the reduction. Based on the leading role of the peri-dichalcogenide bridge, the redox properties of NI derivatives are effectively controlled by the gradual replacement of S with Se and Te atoms in the bridge. To improve the electronic conductivity of NIs, composites with rGO are also synthesized by a simple procedure of mechanical mixing in a centrifugal mixer. The composites rGO/NIs display a good storage performance, the best being the Se-containing analogue. Full article

(This article belongs to the Special Issue Size-Dependent Effects in Materials for Environmental Protection and Energy Application (2nd Edition))

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17 pages, 7812 KiB

Open AccessArticle

Experimental Investigation on the Improvement of Dredged Sludge Using Air–Booster Vacuum Preloading with Polyacrylamide Addition

by Heng Zhang, Lingfeng Guo and Chongzhi Tu

Materials 2025, 18(9), 2065; https://doi.org/10.3390/ma18092065 (registering DOI) - 30 Apr 2025

Abstract

Reducing the water content in soft soil is crucial for improving its load-bearing capacity. However, traditional vacuum preloading demonstrates limited effectiveness for dredged sludge due to its high water content and low permeability, resulting in inadequate consolidation and long treatment durations. To address [...] Read more.

Reducing the water content in soft soil is crucial for improving its load-bearing capacity. However, traditional vacuum preloading demonstrates limited effectiveness for dredged sludge due to its high water content and low permeability, resulting in inadequate consolidation and long treatment durations. To address these limitations, this study proposes a new improvement approach that combines pressurized air injection with a polyacrylamide (PAM) addition to enhance vacuum consolidation. Experimental results demonstrated that cationic polyacrylamide (CPAM) exhibited superior performance in improving water discharge efficiency, which promoted the aggregation of fine soil particles and reduced the clogging of drainage channels through adsorption bridging. The incorporation of pressurized air injection further enhanced consolidation efficiency by increasing hydraulic gradients and inducing micro-fractures in soil, thereby improving soil permeability and vacuum pressure transmission. However, excessive CPAM addition or high-pressure air injection was found to compromise the effectiveness of the vacuum preloading treatment due to drainage channel clogging and extensive soil fracturing. The appropriate consolidation performance was achieved with a 0.075% CPAM addition and 20 kPa air pressure injection, demonstrating a 24.5% increase in water discharge mass and a 30.9% improvement in soil shear strength compared to traditional methods. Microstructural analysis revealed a more compacted soil matrix with reduced porosity and enhanced interparticle interactions. These findings provide valuable insights for improving the treatment efficiency of dredged sludge in coastal regions, particularly in the Nansha District of Guangzhou. Full article

(This article belongs to the Section Polymeric Materials)

23 pages, 3031 KiB

Open AccessArticle

Multi-Objective Optimization of Motor Sealing Performance: Numerical and Experimental Approach

by Weiru Zhou and Zonghong Xie

Materials 2025, 18(9), 2064; https://doi.org/10.3390/ma18092064 (registering DOI) - 30 Apr 2025

Abstract

Rubber seals have been widely applied in mechanical sealing structures in various fields such as automobiles, aerospace, and deep-sea hydraulic systems. The current analysis methods for O-ring sealing performance mainly include experiments and simulations. This study takes the motor sealing structure as the [...] Read more.

Rubber seals have been widely applied in mechanical sealing structures in various fields such as automobiles, aerospace, and deep-sea hydraulic systems. The current analysis methods for O-ring sealing performance mainly include experiments and simulations. This study takes the motor sealing structure as the research object and proposes a multi-objective optimization method for designing sealing structures. Based on the finite element analysis model, the main indicators related to sealing performance were obtained. These indicators transfer to multi-objective optimization analysis to determine the influence of different groove depths on sealing performance. The analysis results show that when the bolt preload is 50 N, a groove depth of 0.9 mm is the optimal design scheme. The optimal relationship between the O-ring diameter D and the sealing structure groove depth is H = 0.6 D. Moreover, a prototype test under the condition of IPX7 requirement verifies the optimal design scheme’s waterproof performance. The proposed method provides multiple design schemes for comprehensive evaluation considering different sealing structures. It reveals that the sealing performance is not only determined by rubber material characteristics but also by seal structure dimension. Full article

(This article belongs to the Section Mechanics of Materials)

80 pages, 5820 KiB

Open AccessReview

Phase Change Materials in Residential Buildings: Challenges, Opportunities, and Performance

by José Pereira, Reinaldo Souza, Jeferson Oliveira and Ana Moita

Materials 2025, 18(9), 2063; https://doi.org/10.3390/ma18092063 (registering DOI) - 30 Apr 2025

Abstract

Phase change materials (PCMs) have emerged as promising solutions for improving thermal management in residential buildings by enhancing thermal storage capacity and reducing energy consumption. This article aims to provide a comprehensive analysis of the application of PCMs in residential construction, focusing on [...] Read more.

Phase change materials (PCMs) have emerged as promising solutions for improving thermal management in residential buildings by enhancing thermal storage capacity and reducing energy consumption. This article aims to provide a comprehensive analysis of the application of PCMs in residential construction, focusing on their thermal properties, benefits, and limitations. A systematic literature review was conducted following PRISMA guidelines, primarily covering studies published between 2015 and 2025. However, key studies published outside this period were also considered due to their relevance and significant contribution to the understanding of PCM performance and application. This analysis explores key parameters affecting PCM performance, including phase transition temperature, thermal conductivity, and material stability. The results highlight that optimized PCM integration can reduce energy consumption by up to 30% and improve indoor thermal comfort. However, challenges such as low thermal conductivity and phase separation still limit their large-scale adoption. The findings provide insights into the advantages and barriers associated with PCM-based systems and propose strategies to enhance their performance, including the use of nanocomposites and improved encapsulation techniques. Full article

(This article belongs to the Special Issue Advances in Phase Change Materials: Characterization, Design and Applications)

22 pages, 13468 KiB

Open AccessArticle

Optimization of SiC–TiC Composite Manufacturing by Electroconsolidation Method

by Vyacheslav Ivzhenko, Jolanta Natalia Latosińska, Edvin Hevorkian, Miroslaw Rucki, Tamara Kosenchuk, Natalia Shamsutdinova, Tadeusz Szumiata, Volodymyr Chishkala and Arturas Kilikevicius

Materials 2025, 18(9), 2062; https://doi.org/10.3390/ma18092062 (registering DOI) - 30 Apr 2025

Abstract

Modern SiC-based materials are of paramount importance in that they serve as wear-resistant and thermal protectors and as next-generation single-photon sources for photonic and quantum solutions. Efforts are underway to identify more efficient methods of manufacturing SiC-based ceramic materials. The objective of this [...] Read more.

Modern SiC-based materials are of paramount importance in that they serve as wear-resistant and thermal protectors and as next-generation single-photon sources for photonic and quantum solutions. Efforts are underway to identify more efficient methods of manufacturing SiC-based ceramic materials. The objective of this paper is to provide a description of the optimization of sintering SiC–TiC composites by the electroconsolidation method. The influence of titanium carbide content on the physical and mechanical properties of SiC–TiC composites obtained by spark plasma sintering (SPS) at a pressure of 45 MPa was studied. It was found that compared to sintered silicon carbide, the porosity of composites with 40 mol% TiC decreased from ~30% to 0%, the crack resistance increased from 2.9 to 6.1 MPa × m^0.5, and the hardness increased from 2.9 to 21.5 GPa. The influence of sintering temperature and holding time on SiC–TiC composites’ physical and mechanical properties during sintering at a pressure of 45 MP was also investigated. An increase in temperature from 1900 °C to 2000 °C resulted in an approximately 30% rise in the composite hardness. An extension of the time allotted for the sintering process from 30 to 45 min resulted in a decrease in both the fracture toughness and hardness of the material. The utilization of two- and three-dimensional vector spaces of material features was proposed as a novel methodology for the description of manufacturing process optimization. Full article

(This article belongs to the Special Issue Manufacturing, Characterization and Modeling of Advanced Materials)

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31 pages, 2017 KiB

Open AccessArticle

Assessment and Comparison of Phenomenological and Physical Constitutive Models for Predicting the Hot Deformation Behavior of Metallic Materials: A Pathway for Sustainable Metal Forming in Al-Kharj Governorate

by Ali Abd El-Aty and Abdallah Shokry

Materials 2025, 18(9), 2061; https://doi.org/10.3390/ma18092061 (registering DOI) - 30 Apr 2025

Abstract

In the context of Al-Kharj city, which is steadily advancing as an industrial and manufacturing hub within Saudi Arabia, this study has significant relevance. The city’s focus on metal forming, fabrication, and materials engineering makes it crucial to optimize processes such as hot [...] Read more.

In the context of Al-Kharj city, which is steadily advancing as an industrial and manufacturing hub within Saudi Arabia, this study has significant relevance. The city’s focus on metal forming, fabrication, and materials engineering makes it crucial to optimize processes such as hot deformation of metallic alloys for various sectors, including aerospace, automotive, oil and gas, and structural applications. By assessing and comparing phenomenological and physical material models for nickel, aluminum, titanium, and iron-based alloys, this study aids Al-Kharj industries in advancing their process simulation and predictive performance. Thus, this study aims to evaluate the proposed phenomenological and physically based constitutive models for Ni-, Al-, Ti-, and Fe-based alloys to enhance the accuracy of high-temperature deformation simulations. Phenomenological models investigated include the Johnson–Cook (JC), Fields and Backofen (FB), and Khan–Huang–Liang (KHL) formulations, while the Zerilli–Armstrong (ZA) model represents the physical category. Additionally, various modifications to these models are explored. Model parameters are calibrated using the Levenberg–Marquardt algorithm to minimize mean square error. Performance is assessed through key statistical metrics, including the correlation coefficient (R), average absolute relative error (AARE), and root mean square error (RMSE). Of the 32 models analyzed, a modified version of the JC model delivers the highest accuracy across all alloys. Furthermore, four other modifications, one each for the JC and ZA models and two for the FB model, exhibit superior predictive capability for specific alloys. This makes this study valuable not just academically, but also as a practical resource to boost Al-Kharj’s industrial competitiveness and innovation capacity. Full article

(This article belongs to the Special Issue Advanced Materials, Machinability and Intelligent Manufacturing Systems)

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20 pages, 6863 KiB

Open AccessArticle

Effect of Simulated Mechanical Filtration by the Stylus Tip on Changes in the Parameters of Areal Surface Texture

by Rafal Reizer, Andrzej Dzierwa, Wieslaw Żelasko and Zuzanna Pawlus

Materials 2025, 18(9), 2060; https://doi.org/10.3390/ma18092060 (registering DOI) - 30 Apr 2025

Abstract

The objective of this work was to study distortion of the 3D surface textures measurement using the stylus tip technique. This distortion was simulated using a dilation procedure. Topographies of many machined surfaces of various characters measured using a white light interferometer were [...] Read more.

The objective of this work was to study distortion of the 3D surface textures measurement using the stylus tip technique. This distortion was simulated using a dilation procedure. Topographies of many machined surfaces of various characters measured using a white light interferometer were analysed. The growth in the tip of the radius of the stylus produced larger changes in surface texture. Mechanical filtration by a stylus tip caused a reduction in the amplitude parameters, hybrid parameters, and average radius of the peak curvature. Variations in skewness (Ssk) and kurtosis (Sku) depended on the type of surface. The depth and density of the furrows had a tendency to decrease. The measurement results were more distorted for a higher roughness amplitude and a smaller main wavelength. Full article

(This article belongs to the Special Issue Precision and Ultra-Precision Subtractive and Additive Manufacturing Processes of Alloys and Steels, 2nd Edition)

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17 pages, 6902 KiB

Open AccessArticle

Effect of Waste Cigarette Butt Fibers on the Properties and CO₂ Footprint of Bitumen

by Kai Yang, Cheng Cheng, Yong Yan, Qinglin Wu and Ru Du

Materials 2025, 18(9), 2059; https://doi.org/10.3390/ma18092059 (registering DOI) - 30 Apr 2025

Abstract

This research utilized recycled acetate fibers from discarded cigarette butts (CBs) as reinforcing materials, reducing solid waste and enhancing the properties of bitumen. The surface properties of the fibers significantly impacted the binder characteristics. The treatment of CB fibers with anhydrous ethanol was [...] Read more.

This research utilized recycled acetate fibers from discarded cigarette butts (CBs) as reinforcing materials, reducing solid waste and enhancing the properties of bitumen. The surface properties of the fibers significantly impacted the binder characteristics. The treatment of CB fibers with anhydrous ethanol was employed to remove the plasticizer glycerol triacetate (GTA), enabling the better homogeneity of the fibers in the binder. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to assess the effectiveness of the fiber treatment. A dynamic shear rheometer (DSR) was used to explore the properties of bitumen with varying CB contents (0%, 0.25%, 0.75%, and 1.25% by weight). A whole life cycle analysis further confirmed the eco-efficiency of CB binders. The results show that the pretreatment effectively removed GTA, leading to a more homogeneous dispersion of fibers in the binder. Adding CBs can significantly improve bitumen properties, but this effect does not increase with higher dosages; when the CB content exceeded 1.25%, a reduction in fatigue resistance was observed. Among the tested dosages, the optimal amount was 0.75%, which improved the high-temperature performance of the binder by 2.7 times, the medium-temperature fatigue life by 1.78 times, and the low-temperature performance by 1.08 times. In terms of ecological benefits, the addition of CB fibers to bitumen pavement reduced carbon emissions by two-thirds compared to traditional bitumen pavement, resulting in a significant decrease in carbon emissions. This study provides valuable insights into the construction of sustainable transportation infrastructure. Full article

(This article belongs to the Special Issue Integrating Sustainable Innovations in Pavement Materials and Engineering)

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16 pages, 4844 KiB

Open AccessArticle

Electrical and Optical Properties Depending on the Substitution Position of a Novel Indolocarbazole Dimer

by Jiyun Kim, Suhyeon Jeong, Sangwook Park, Saeyoung Oh, Kiho Lee, Soonhang Lee, Jihoon Lee, Hayoon Lee and Jongwook Park

Materials 2025, 18(9), 2058; https://doi.org/10.3390/ma18092058 (registering DOI) - 30 Apr 2025

Abstract

Two innovative dimeric derivatives of indolo[3,2,1-jk]carbazole (ICz), named 7,7′-biindolo[3,2,1-jk]carbazole (ICzDO) and 4,4′-biindolo[3,2,1-jk]carbazole (ICzDM), have been developed. Both dimers consist of two ICz units coupled through distinct ortho and meta positions. In the solution state, ICzDO and ICzDM exhibited photoluminescence (PL) maxima at 379 [...] Read more.

Two innovative dimeric derivatives of indolo[3,2,1-jk]carbazole (ICz), named 7,7′-biindolo[3,2,1-jk]carbazole (ICzDO) and 4,4′-biindolo[3,2,1-jk]carbazole (ICzDM), have been developed. Both dimers consist of two ICz units coupled through distinct ortho and meta positions. In the solution state, ICzDO and ICzDM exhibited photoluminescence (PL) maxima at 379 nm and 391 nm, demonstrating emission in the deep-blue region. These compounds show exceptionally narrow emission spectra, characterized by full width at half maximum (FWHM) of 28 nm for ICzDO and 26 nm for ICzDM. In the film state, ICzDM exhibited a photoluminescence (PL) maximum at 428 nm, whereas ICzDO showed a red-shifted emission at 507 nm with a broad full width at half maximum (FWHM) of 87 nm, indicating significant red-shifted excimer emission characteristics. This is attributed to its aggregation-enhanced excimer emission (AEEE) characteristics. When used as host materials for red phosphorescent OLEDs, both compounds enabled efficient energy transfer. Devices using ICzDM as the host attained highly efficient external quantum efficiency (EQE) values of 13.5%, coupled with remarkable color purity represented by Commission Internationale de l’Éclairage (CIE) coordinates of (0.685, 0.314). These findings emphasize how strategic variations in linking positions of identical chromophores can markedly enhance OLED device performance, paving the way for innovative material designs in next-generation organic semiconductor technologies. Full article

(This article belongs to the Special Issue Advancements in Optical Materials and Photonic Device Technologies)

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22 pages, 21745 KiB

Open AccessArticle

Fabrication and Properties of Zn-Containing Intermetallic Compounds as Sacrificial Anodes of Zn-Based Implants

by Kelei Li, Junwei Li, Tiebao Wang, Xin Wang, Yumin Qi, Lichen Zhao and Chunxiang Cui

Materials 2025, 18(9), 2057; https://doi.org/10.3390/ma18092057 (registering DOI) - 30 Apr 2025

Abstract

In the field of degradable metals, Zn-based implants have gradually gained more attention. However, the relatively slow degradation rate compared with the healing rate of the damaged bone tissue, along with the excessive Zn²⁺ release during the degradation process, limit the application [...] Read more.

In the field of degradable metals, Zn-based implants have gradually gained more attention. However, the relatively slow degradation rate compared with the healing rate of the damaged bone tissue, along with the excessive Zn²⁺ release during the degradation process, limit the application of Zn-based implants. The use of intermetallic compounds with more negative electrode potentials as sacrificial anodes of Zn-based implants is likely to be a feasible approach to resolve this contradiction. In this work, three intermetallic compounds, MgZn₂, CaZn₁₃, and Ca₂Mg₆Zn₃, were prepared. The phase structures, microstructures, and relevant properties, such as thermal stability, in vitro degradation properties, and cytotoxicity of the compounds, were investigated. The XRD patterns indicate that the MgZn₂ and CaZn₁₃ specimens contain single-phase MgZn₂ and CaZn₁₃, respectively, while the Ca₂Mg₆Zn₃ specimen contains Mg₂Ca and Ca₂Mg₆Zn₃ phases. After purifying treatment in 0.9% NaCl solution, high purity Ca₂Mg₆Zn₃ phase was obtained. Thermal stability tests suggest that the MgZn₂ and CaZn₁₃ specimens possess good thermal stability below 773 K. However, the Ca₂Mg₆Zn₃ specimen melted at around 739.1 K. Polarization curve tests show that the corrosion potentials of MgZn₂, CaZn₁₃, and Ca₂Mg₆Zn₃ in simulated body fluid (SBF) were −1.063 V_SCE, −1.289 V_SCE, and −1.432 V_SCE, which were all more negative than that of the pure Zn specimen (−1.003 V_SCE). Clearly, these compounds can act as sacrificial anodes in Zn-based implants. The immersion tests indicate that these compounds were degraded according to the atomic ratio of the elements in each compound. Besides that, the compounds can efficiently induce Ca-P deposition in SBF. Cytotoxicity tests demonstrate that the 10% extracts prepared from these compounds exhibit good cell activity on MC3T3-E1 cells. Full article

(This article belongs to the Special Issue Physical Metallurgy of Metals and Alloys (3rd Edition))

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26 pages, 18959 KiB

Open AccessReview

A Review on the Progressive Collapse of Reinforced Concrete Flat Slab–Column Structures

by Xiao Li, Tengfang Dong, Chengquan Wang, Weiwei Zhang, Rongyang Liu and Jingjing Wang

Materials 2025, 18(9), 2056; https://doi.org/10.3390/ma18092056 (registering DOI) - 30 Apr 2025

Abstract

Reinforced concrete flat slab–column structures, lacking the redundancy provided by a beam–column system, are susceptible to punching shear failure under extreme loading conditions, which may lead to progressive collapse with catastrophic consequences. A systematic review of recent advancements in the progressive collapse resistance [...] Read more.

Reinforced concrete flat slab–column structures, lacking the redundancy provided by a beam–column system, are susceptible to punching shear failure under extreme loading conditions, which may lead to progressive collapse with catastrophic consequences. A systematic review of recent advancements in the progressive collapse resistance of flat slab–column systems has been provided, categorizing the methodologies into experimental investigation, theoretical analysis, and numerical simulation. Experimental studies primarily utilize the Alternative Load Path methodology, incorporating both quasi-static and dynamic loading protocols to assess structural performance. Different column removal scenarios (e.g., corner, edge, and interior column failures) clarify the load redistribution patterns and the evolution of resistance mechanisms. Theoretical frameworks focus on tensile and compressive membrane actions, punching shear mechanism, and post-punching shear mechanism. Analytical models, incorporating strain-hardening effects and deformation compatibility constraints, show improved correlation with experimental results. Numerical simulations use multi-scale modeling strategies, integrating micro-level joint models with macro-level structural assemblies. Advanced finite element analysis techniques effectively replicate collapse behaviors under various column failure scenarios, validated by full-scale test data. This synthesis identifies key research priorities and technical challenges in collapse-resistant design, establishing theoretical foundations for future investigations of flat slab systems under multi-hazard coupling effects. Full article

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

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21 pages, 16019 KiB

Open AccessArticle

The Influence of the Annular Nozzle’s Structural Parameters on Powder Stream Convergence for Laser-Directed Energy Deposition

by Bobo Li, Weiyi Wang, Donglai Li, Zong Liu, Yuhang Ren, Yushi Wang and Guang Yang

Materials 2025, 18(9), 2055; https://doi.org/10.3390/ma18092055 (registering DOI) - 30 Apr 2025

Abstract

Laser-directed energy deposition (L-DED) technology is increasingly used in the manufacturing industry, in which the powder convergence of the feeding nozzle affects the accuracy and quality of additive manufacturing parts. However, there is nothing in the literature that gives a comprehensive optimization scheme [...] Read more.

Laser-directed energy deposition (L-DED) technology is increasingly used in the manufacturing industry, in which the powder convergence of the feeding nozzle affects the accuracy and quality of additive manufacturing parts. However, there is nothing in the literature that gives a comprehensive optimization scheme for the powder feeding structure of the ring nozzle. In order to investigate the effect of the internal structure for the annular nozzle on powder convergence, in this paper, finite element analysis models for the annular nozzle are established, and the Lagrangian–Eulerian method is used to analyze the influence of different outlet shapes, powder feeding inclination angles, outlet gaps, and inlet shapes of annular nozzles on the powder convergence. The results indicate that the parallel outlet shape is more suitable for the annular nozzle, and the waist diameter of the powder stream decreases gradually with the decrease in the power feeding inclination angle and the outlet gap. The inlet shape of the powder storage chamber plays a guiding role in the moving direction of the powder particles; when the powder feeding inclination angle is 17° and the outlet gap is 0.5 mm, the waist diameter of the powder stream is reduced by 49%. In addition, the effects of particle size, carrier gas rate, and laser shielding gas on the powder convergence are also studied, and the results indicate that, with the reduction of particle size and carrier gas rate, the powder convergence can be effectively improved, and the waist diameter of powder stream becomes 1.42 mm. With the increase in the laser shielding gas rate, the powder convergence position moves down. The research results provide a basis for the structural optimization to design a high-convergence annular nozzle for the laser additive manufacturing process. Full article

(This article belongs to the Special Issue Recent Trends in Solid-State Additive Manufacturing of Alloys)

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