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Volume 18
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Materials, Volume 18, Issue 4 (February-2 2025) – 188 articles

Cover Story (view full-size image): We designed a more sensitive sensor for CEA detection based on the Fluorescent Resonance Energy Transfer (FRET) between Yb3+ high-level-doping upconversion nanoparticles (UCNPs, energy donor) and polydopamine nanoparticles (PDA NPs, energy acceptor). This work employed Yb3+ high-level-doping UCNPs (i.e., NaYF4@NaYbF4:1%Tm@NaYF4) as the energy donor, which resulted in not only more than 10 times the upconversion luminescence intensity than that of the Yb3+ low-level-doping UCNPs (i.e., NaYF4@NaYF4:20%Yb,0.2%Tm@NaYF4) but also the ability to better overcome the influence of unfavorable factors, such as instrumental noise. The research results showed that the sensitivity of the sensor was largely promoted to 0.013 ng/mL in diluted fetal bovine serum and 0.0117 ng/mL in a HEPES buffer solution. View this paper
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16 pages, 2584 KiB  
Article
Experimental Investigation of the Drying Shrinkage Performance of a Modified Ceramsite Geopolymer Concrete
by Peng Deng, Xuening Wang, Jian Guo, Yan Liu and Qi Zheng
Materials 2025, 18(4), 915; https://doi.org/10.3390/ma18040915 - 19 Feb 2025
Viewed by 357
Abstract
The experiments were divided into two groups to establish a drying shrinkage model suitable for modified ceramsite geopolymer concrete (MCGC). In the first experimental group, via comparison with dry ceramsite (untreated), a method for modifying the ceramsite surface with a 6% silicone resin [...] Read more.
The experiments were divided into two groups to establish a drying shrinkage model suitable for modified ceramsite geopolymer concrete (MCGC). In the first experimental group, via comparison with dry ceramsite (untreated), a method for modifying the ceramsite surface with a 6% silicone resin was proposed which could reduce its water absorption, enhance the compressive strength and slump of the corresponding concrete, and decrease the drying shrinkage. The second group systematically explored the influences of control factors on MCGC prepared from modified ceramsite. Different water/binder (w/b) ratios, [Na2O]/b ratios, and metakaolin content (MK/b) ratios were used in the experiment. Compressive strength and drying shrinkage tests were performed for 90 d. High w/b and Na2O/b ratios could enhance drying shrinkage. Moreover, 8% Na2O/b enhanced the compressive strength. Low compressive strength was obtained using 10% Na2O/b. A high MK/b ratio reduced drying shrinkage. However, high w/b and MK/b ratios hindered strength development. Finally, a model predicting drying shrinkage for MCGC with a high prediction accuracy was proposed by considering three control factors. Due to the variety of ceramsite pretreatment methods and the considered factor limitations, the model had potential for additional enhancements. Full article
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27 pages, 6813 KiB  
Article
Application of Unprocessed Waste Tyres in Pavement Base Structures: A Study on Deformation and Stress Analysis Using Finite Element Simulation
by Baoying Shen, Hui Tian, Wenruo Fan, Lu Zhang and Hui Wang
Materials 2025, 18(4), 914; https://doi.org/10.3390/ma18040914 - 19 Feb 2025
Viewed by 324
Abstract
In this study, numerical simulations using the Abaqus finite element model were performed to evaluate the effects of incorporating waste tyres of varying sizes into the base layer as part of a coupled tyre–pavement structure. The tyre-reinforced structure demonstrated superior deformation resilience, attributed [...] Read more.
In this study, numerical simulations using the Abaqus finite element model were performed to evaluate the effects of incorporating waste tyres of varying sizes into the base layer as part of a coupled tyre–pavement structure. The tyre-reinforced structure demonstrated superior deformation resilience, attributed to the hyperelastic properties of tyre rubber, underscoring its potential for applications where deformation recovery is essential. For achieving a uniform settlement, the entire tyre stacking scheme is recommended, whereas the one-third tyre configuration is ideal for minimising displacement. The one-half tyre configuration provides a balanced approach, optimising resource utilisation for structures with moderate performance requirements. The inclusion of tyres increases the equivalent stress within the cement-stabilised gravel layer beneath the tyre, and this effect is less pronounced with smaller tyre sizes. Notably, the projected portion of the tyre tread enhances the bearing capacity of the base structure, improving the load distribution and overall structural performance. The middle and bottom surface layers were identified as the most critical for controlling deformation and stress distribution, while a moderate modulus is advised for the surface course to achieve a balance between deformation control and stress uniformity. The integration of high-modulus layers with tyre reinforcement offers an optimised solution for both deformation management and stress distribution. This study highlights the potential of tyre-reinforced pavements as an innovative and sustainable construction practice, particularly suited for light to moderate traffic conditions. Further research is recommended to explore the long-term environmental and economic benefits, as well as the impacts of tyre composition and ageing on performance. Full article
(This article belongs to the Special Issue Performance-Related Material Properties of Asphalt Mixture Components (3rd Edition))
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13 pages, 2963 KiB  
Article
Flexural Strength and Surface Properties of 3D-Printed Denture Base Resins—Effect of Build Angle, Layer Thickness and Aging
by Shaimaa Fouda, Wenjie Ji, Mohammed M. Gad, Maram A. AlGhamdi and Nadja Rohr
Materials 2025, 18(4), 913; https://doi.org/10.3390/ma18040913 - 19 Feb 2025
Viewed by 375
Abstract
A variety of printable resins for denture bases are available, without detailed instructions on print parameters. This study aimed to evaluate the effect of the printing build angle and the layer thickness of 3D-printed denture base resins before and after thermocyclic aging on [...] Read more.
A variety of printable resins for denture bases are available, without detailed instructions on print parameters. This study aimed to evaluate the effect of the printing build angle and the layer thickness of 3D-printed denture base resins before and after thermocyclic aging on flexural strength values and surface properties. The flexural strength, surface roughness (Ra, Rz) and hardness (HM, HV2) of two 3D-printed denture base resins (Formlabs (FL) and V-print dentbase, VOCO, (VC)) were therefore compared to a conventionally pressed cold-curing control material (PalaXpress (PP)). The specimens were printed at a 0°, 45° or 90° build angle and the layer thickness was varied for FL at 50 and 100 µm and evaluated before and after thermocyclic aging (N = 200; n = 10). Differences in flexural strength values were analyzed using multifactorial ANOVAs (α = 0.05). The build angle and aging significantly affected the flexural strength of the 3D-printed denture base resins (p < 0.05), while the layer thickness showed no effect for FL (p = 0.461). The required threshold value of 65 MPa defined by ISO 20795-1 was exceeded by PP (70.5 MPa ± 5.5 MPa), by FL when printed at 90° (69.3 MPa ± 7.7 MPa) and by VC at 0° (69.0 MPa ± 4.6 MPa). The choice of an appropriate build angle for each material and printing technology is crucial for the flexural strength and consequently the clinical longevity of a printed denture base. Full article
(This article belongs to the Special Issue Research and Application Advantages of 3D-Printed Dental Materials)
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10 pages, 3429 KiB  
Communication
Study of Microstructure and Mechanical Properties of 800H Alloy During Creep
by Menglin Gao, Shengjun Xia, Chunfa Huang, Xing Hu, Shuaiheng Liang, Wenlu Zhang and Qiulin Li
Materials 2025, 18(4), 912; https://doi.org/10.3390/ma18040912 - 19 Feb 2025
Viewed by 275
Abstract
Creep is one of the primary degradation mechanisms affecting the performance of the 800H alloy under long-term high-temperature stress conditions. Understanding the microstructural evolution during creep and developing a quantitative model to relate these changes to mechanical properties are essential for assessing creep [...] Read more.
Creep is one of the primary degradation mechanisms affecting the performance of the 800H alloy under long-term high-temperature stress conditions. Understanding the microstructural evolution during creep and developing a quantitative model to relate these changes to mechanical properties are essential for assessing creep damage and ensuring the safe operation of high-temperature equipment. By conducting a multiscale quantitative characterization of the microstructures in the 800H alloy across different creep stages, we systematically examined the evolution of various microstructural features and their influence on Young’s modulus. A quantitative prediction model of Young’s modulus based on microstructural characteristics was developed, achieving a prediction accuracy exceeding 95% with a mean absolute percentage error of just 1.59% compared to experimental values. This work not only elucidates the intrinsic relationship between microstructural features and macroscopic mechanical properties but also provides a foundation for the in-service creep damage assessment of high-temperature components. Full article
(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys (Second Volume))
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15 pages, 6603 KiB  
Article
Contribution of Active Surface of NiFe-Layered Double Hydroxide on the Removal of Methyl Orange
by Yanping Zhao, Fengzhu Lv, Yanwen Ou, Guocheng Lv and Shifeng Zhao
Materials 2025, 18(4), 911; https://doi.org/10.3390/ma18040911 - 19 Feb 2025
Viewed by 261
Abstract
Layered double hydroxides (LDHs) have potential applications for pollutant removal. Enhancing their pollutant removal ability by fully utilizing the synergistic effects of physical adsorption and chemical catalysis has received widespread attention. In this study, a high methyl orange (MO) removal capacity was achieved [...] Read more.
Layered double hydroxides (LDHs) have potential applications for pollutant removal. Enhancing their pollutant removal ability by fully utilizing the synergistic effects of physical adsorption and chemical catalysis has received widespread attention. In this study, a high methyl orange (MO) removal capacity was achieved by utilizing the synergistic effects of physical adsorption and chemical catalysis of NiFe-LDH. wNiFe-LDH showed a significant removal amount of MO, up to 506.30 mg/g due to its reserving of the active surface to the largest extent. Experiment and molecular simulation clarified the high removal capacity derived from surface adsorption and the degradation ability of the active surface. The presence of more -OH groups on the surface enhanced the removal of MO, and the vacancies in the surface were beneficial for the formation of •O2− and contributed to the degradation of MO. As K2S2O8 was introduced, the removal rate of MO improved to 100% from 60.67%. However, a deeper study showed that the degradation was incomplete, as K2S2O8 inhibited the formation of •O2−, and the active species in the system changed to holes. The degradation path of MO was also altered. Thus, this study gives new insight into the reactivity of the active surface of NiFe-LDH and affords a new path to preserve the active surface. Full article
(This article belongs to the Special Issue Application and Modification of Clay Minerals)
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15 pages, 4807 KiB  
Article
Save Forests Through Sustainable Papermaking: Repurposing Herbal Waste and Maple Leaves as Alternative Fibers
by Haradhan Kolya and Chun-Won Kang
Materials 2025, 18(4), 910; https://doi.org/10.3390/ma18040910 - 19 Feb 2025
Viewed by 578
Abstract
This study explores a sustainable papermaking approach to contribute to forest conservation by repurposing delignified herbal waste and maple leaves as alternative cellulose sources. By reducing reliance on traditional wood-based materials, this method supports forest conservation while promoting environmental sustainability and creating economic [...] Read more.
This study explores a sustainable papermaking approach to contribute to forest conservation by repurposing delignified herbal waste and maple leaves as alternative cellulose sources. By reducing reliance on traditional wood-based materials, this method supports forest conservation while promoting environmental sustainability and creating economic opportunities from agricultural byproducts. Controlled experiments were conducted to extract cellulose and form paper using four fiber compositions: 100% leaf (P1), 100% herbal waste (P2), 75% leaf + 25% herbal waste (P3), and 75% leaf + 25% wood pulp (P4). Both treated and untreated herbal waste and leaves were characterized using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Diffraction (XRD) to analyze chemical functionality and structural changes. The Kürschner cellulose content (22.4% in herbal waste and 15.2% in maple leaves) was determined through concentrated nitric acid and ethanol treatments, confirming high cellulose levels suitable for papermaking. Papers produced from these compositions exhibited enhanced mechanical properties, with the P2 sample (100% herbal waste) demonstrating the highest tensile strength (with P2 exhibiting a tensile strength of 1.84 kN/m) due to its elevated cellulose content. This innovative recycling approach contributes to deforestation reduction by valorizing agricultural waste materials, highlighting the feasibility of integrating alternative fibers into paper manufacturing. These findings present a promising pathway toward an eco-friendly, forest-saving paper industry while adding economic value to agro-waste resources. Full article
(This article belongs to the Section Green Materials)
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22 pages, 5526 KiB  
Article
Preparation and Characterization of Thermal Storage Ceramics from Iron-Containing Solid Waste
by Cheng Xue, Peiyang Lu, Zhiwei Wu and Yu Li
Materials 2025, 18(4), 909; https://doi.org/10.3390/ma18040909 - 19 Feb 2025
Viewed by 284
Abstract
Copper slag and red mud with high iron contents were discharged with an annual global amount of 37.7 and 175 million tons but had low utilization rates due to wide reuse difficulties. Studies on their large-scale utilization have become urgent. Thermal storage ceramic [...] Read more.
Copper slag and red mud with high iron contents were discharged with an annual global amount of 37.7 and 175 million tons but had low utilization rates due to wide reuse difficulties. Studies on their large-scale utilization have become urgent. Thermal storage ceramic is a kind of energy storage material with high-added value and a potentially large market. In this study, a method to convert copper slag and red mud into thermal storage ceramics through a ceramic fabrication process was proposed. Four samples were prepared and characterized by XRD and SEM-EDS, as well as physical and thermal property tests. The relationships among phase composition, microstructure, and properties were further discussed. The results showed the thermal storage ceramic from copper slag had the best properties with a flexural strength of 68.02 MPa and a thermal storage density of 1238.25 J/g, both equal and nearly twice those of traditional heat storage materials like Magnesia Fire Bricks and corundum. The grain sizes of mineral phases in the prepared thermal storage ceramics have significant impacts on the performance of the material. Increasing the proportion of copper slag in thermal storage ceramics from red mud could enhance their performance. This study provides a new perspective on the low-cost preparation of thermal storage ceramics and large-scale utilization of iron-containing solid waste. Full article
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15 pages, 4922 KiB  
Article
Formation Mechanism and Motion Characteristics of Multiple Jets in Spherical Section Free Surface Electrospinning
by Jing Yin and Lan Xu
Materials 2025, 18(4), 908; https://doi.org/10.3390/ma18040908 - 19 Feb 2025
Viewed by 262
Abstract
In this study, during the efficient preparation of nanofibers using a spherical section free surface electrospinning (SSFSE) device with different sphere radii, the formation mechanism and motion characteristics of multiple jets were thoroughly investigated through the numerical simulation method. The mechanical model of [...] Read more.
In this study, during the efficient preparation of nanofibers using a spherical section free surface electrospinning (SSFSE) device with different sphere radii, the formation mechanism and motion characteristics of multiple jets were thoroughly investigated through the numerical simulation method. The mechanical model of multiple jets was established, and the key role of electric field intensity in the formation and motion of jets was defined; in addition, the relationship between the jet initial velocity and the electric field intensity distribution on the solution surface was established. On this basis, a magnetohydrodynamic model was introduced, and a turbulence model as well as a volume of fluid model were combined to numerically simulate the jet motion during the SSFSE process. The results showed that as the sphere radius increased, the maximum velocity of the jets gradually decreased. However, the area of multiple jets generated increased, and the interaction force between the jets increased, resulting in a more obvious outward expansion of the jet trajectory. Therefore, the optimal SSFSE device with a sphere radius of 75 mm was determined. Finally, the results of numerical simulation were verified by experiments using a polymeric solution with low conductivity. This study can play a guiding role in effectively increasing the number of jets per unit area of solution surface in actual production, thus achieving continuous, uniform, and efficient preparation of micro-/nanofibers. Full article
(This article belongs to the Special Issue Properties and Applications of Advanced Textile Materials)
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16 pages, 3936 KiB  
Article
Investigation of the Influence of Alloying Elements Ni, Cr, Co and Mo on the Crystallization Process, Phase Composition and Corrosion Resistance of AlSi25Cu4Cr and AlSi25Cu5Cr Alloys
by Boyan Dochev, Desislava Dimova, Karel Trojan, Jiří Čapek, Kalina Kamarska and Bozhana Chuchulska
Materials 2025, 18(4), 907; https://doi.org/10.3390/ma18040907 - 19 Feb 2025
Viewed by 302
Abstract
To increase the mechanical and improve the operational properties of the AlSi25Cu4Cr and AlSi25Cu5Cr alloys, combinations of the alloying elements Ni, Co and Mo were used. The AlSi25Cu4Cr alloy was additionally alloyed with both Ni and Mo and Ni, Co and Mo, and [...] Read more.
To increase the mechanical and improve the operational properties of the AlSi25Cu4Cr and AlSi25Cu5Cr alloys, combinations of the alloying elements Ni, Co and Mo were used. The AlSi25Cu4Cr alloy was additionally alloyed with both Ni and Mo and Ni, Co and Mo, and the AlSi25Cu5Cr alloy was alloyed with Co and Mo in different concentrations. The dental alloys “wiron light” and “wironit” were used to introduce the elements Ni, Co, Mo, as well as additional amounts of Cr into the composition of the base compositions. The thermal analysis recorded a decrease in the liquidus and solidus temperatures of the base alloys, as well as a narrowing of their crystallization temperature range as a result of the added alloying elements. The influence of the used chemical elements on the phase composition of the alloys was established by X-ray diffraction. The elements Cr and Mo do not form secondary strengthening phases but dissolve in the α-solid solution. The results of the corrosion tests conducted in 1 M HCl solution and 1 M H2SO4 solution for 336 h and 504 h show that the elements Ni, Co and Mo improve the corrosion resistance of the alloys. Full article
(This article belongs to the Special Issue Investigation of Microstructural and Corrosion Properties of Steels and Light Alloys (2nd Edition))
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15 pages, 250 KiB  
Review
Antiviral Surface Coatings: From Pandemic Lessons to Visible-Light-Activated Films
by Plinio Innocenzi
Materials 2025, 18(4), 906; https://doi.org/10.3390/ma18040906 - 19 Feb 2025
Viewed by 207
Abstract
The increasing need for effective antiviral strategies has led to the development of innovative surface coatings to combat the transmission of viruses via fomites. The aim of this review is to critically assess the efficacy of antiviral coatings in mitigating virus transmission, particularly [...] Read more.
The increasing need for effective antiviral strategies has led to the development of innovative surface coatings to combat the transmission of viruses via fomites. The aim of this review is to critically assess the efficacy of antiviral coatings in mitigating virus transmission, particularly those activated by visible light. The alarm created by the COVID-19 pandemic, including the initial uncertainty about the mechanisms of its spread, attracted attention to fomites as a possible source of virus transmission. However, later research has shown that surface-dependent infection mechanisms need to be carefully evaluated experimentally. By briefly analyzing virus–surface interactions and their implications, this review highlights the importance of shifting to innovative solutions. In particular, visible-light-activated antiviral coatings that use reactive oxygen species such as singlet oxygen to disrupt viral components have emerged as promising options. These coatings can allow for obtaining safe, continuous, and long-term active biocidal surfaces suitable for various applications, including healthcare environments and public spaces. This review indicates that while the significance of fomite transmission is context-dependent, advances in material science provide actionable pathways for designing multifunctional, visible-light-activated antiviral coatings. These innovations align with the lessons learned from the COVID-19 pandemic and pave the way for sustainable, broad-spectrum antiviral solutions capable of addressing future public health challenges. Full article
(This article belongs to the Section Thin Films and Interfaces)
21 pages, 9554 KiB  
Article
Dual-Scale Collaborative Optimization of Microtubule Self-Healing Composites Based on Variable-Angle Fiber Design
by Peng Li, Baijia Fan, Shenbiao Wang, Jianbin Tan and Wentao Cheng
Materials 2025, 18(4), 905; https://doi.org/10.3390/ma18040905 - 19 Feb 2025
Viewed by 292
Abstract
To enhance the mechanics and self-healing properties of the self-healing composite, this study introduces an innovative optimization method for variable-angle fiber-reinforced self-healing composites with microtubule network carriers. The study aims to minimize macroscopic structural compliance and carrier head loss. Firstly, a topological description [...] Read more.
To enhance the mechanics and self-healing properties of the self-healing composite, this study introduces an innovative optimization method for variable-angle fiber-reinforced self-healing composites with microtubule network carriers. The study aims to minimize macroscopic structural compliance and carrier head loss. Firstly, a topological description function (TDF) for the self-healing composite was introduced, taking into account the configuration and geometry of the macroscopic structure and microtubule network carrier as design variables. Secondly, the relationship between the fiber laying angle and component spindle direction was established. An element stiffness matrix for variable-angle fibers was derived to determine the compliance of the self-healing composite. Then, the microtubule network head loss was calculated based on the Hardy Cross method. Finally, by integrating the Moving Morphable Component (MMC) method and the enumeration method, a dual-scale collaborative optimization framework was developed. The set of double-objective Pareto non-inferior solutions of the self-healing composite was obtained by iteration. Numerical examples show that (1) under the same optimization conditions, the non-inferior solution set of variable-angle fiber design is superior to those of fixed-angle fiber designs (0°, 45°, and 90°). (2) Compared with single-objective (compliance) optimization of the carrier-free composite, the Pareto solution set of the variable-angle dual-scale collaborative optimization can provide a better compliance optimization solution, and the maximum compliance solution of the solution set is only 10.64% higher. This paper proposes a method combining variable-angle and dual-scale collaborative optimization, which provides a useful reference for the topology design of a self-healing composite. Full article
(This article belongs to the Topic Advanced Biomaterials: Processing and Applications)
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25 pages, 9563 KiB  
Article
Porous Mortars Incorporating Active Biochar from Olive Stone Waste and Recycled Masonry Aggregate: Effects of Accelerated Carbonation Curing
by Antonio Manuel Merino-Lechuga, Ágata González-Caro, Álvaro Caballero, José Ramón Jiménez, José María Fernández-Rodrígez and David Suescum-Morales
Materials 2025, 18(4), 904; https://doi.org/10.3390/ma18040904 - 19 Feb 2025
Viewed by 299
Abstract
This study investigated the use of activated biochar derived from olive stone waste and recycled masonry aggregates in porous mortar mixtures and assessed their behaviour under accelerated carbonation curing conditions. Three mortar mixtures were produced, incorporating 0%, 5%, and 10% activated biochar by [...] Read more.
This study investigated the use of activated biochar derived from olive stone waste and recycled masonry aggregates in porous mortar mixtures and assessed their behaviour under accelerated carbonation curing conditions. Three mortar mixtures were produced, incorporating 0%, 5%, and 10% activated biochar by volume. The physical, chemical, and mechanical properties of the mortars were analysed, including the compressive strength, flexural strength, water absorption, porosity, and CO2 capture capacity. Additionally, calorimetry tests were performed on cement pastes with 0%, 0.5%, 1%, 3%, 15%, and 20% activated biochar to evaluate their impact on setting times and ensure compatibility between activated biochar and cement. The results showed that the addition of biochar improved mechanical properties, particularly under accelerated carbonation curing, whereas active biochar (AcB) significantly enhanced the compressive and flexural strengths. Furthermore, biochar incorporation boosted CO2 capture efficiency, with the 10% biochar mix showing up to 147% higher CO2 uptake, compared with a control. These findings suggest that activated biochar and recycled masonry aggregates can be effectively utilised to develop sustainable construction materials and thereby contribute to carbon sequestration and the reduction in environmental impacts. This research fills the gaps in the current knowledge on the use of activated biochar from olive stones waste in cement-base materials under accelerated carbonation conditions. Full article
(This article belongs to the Section Construction and Building Materials)
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15 pages, 5196 KiB  
Article
Assessment of Physicochemical Properties of Dust from Crushing High-Carbon Ferrochrome: Methods for Agglomeration
by Otegen Sariyev, Assylbek Abdirashit, Maral Almagambetov, Nurzhan Nurgali, Bauyrzhan Kelamanov, Dauren Yessengaliyev and Azamat Mukhambetkaliyev
Materials 2025, 18(4), 903; https://doi.org/10.3390/ma18040903 - 19 Feb 2025
Viewed by 195
Abstract
Fine classes of metal dust generated during the production of ferroalloys increase the likelihood of irretrievable losses, creating the prerequisites for the development of rational methods for processing this material. One of the known technologies for recycling dispersed raw materials in metallurgical processing [...] Read more.
Fine classes of metal dust generated during the production of ferroalloys increase the likelihood of irretrievable losses, creating the prerequisites for the development of rational methods for processing this material. One of the known technologies for recycling dispersed raw materials in metallurgical processing is their direct remelting. Although this technology is easily feasible, it has several significant drawbacks, among which the main problem remains the high dust carryover of fine material by ascending gas-thermal flows. A potential solution could be the preliminary preparation of raw materials through agglomeration. Domestic enterprises producing various types of ferroalloys have the necessary infrastructure and equipment for agglomerating dispersed ore materials, but the lack of experience and resource-saving technologies for processing metal dust prevents their full integration into metallurgical processing. In this regard, there is significant interest and demand from ferroalloy enterprises for the development of new methods to involve dispersed metal production waste in secondary recycling, adapted to existing agglomeration equipment. Numerous studies have shown that the cheapest method of agglomeration is briquetting. Given the advancement of briquetting technologies, as well as the use of the latest equipment and binding materials in this process, it can be assumed that this will allow for more complete integration of aspiration dust from ferrochrome crushing into metallurgical processing. To test this assumption, studies were conducted on the physicochemical properties of aspiration dust from ferrochrome crushing, assessing the possibility of obtaining an agglomerated product with the required strength parameters. The results of these studies demonstrated the fundamental possibility of producing high-carbon ferrochrome from briquetted material made from aspiration dust of ferrochrome crushing. Full article
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15 pages, 3501 KiB  
Article
CO2-Responsive Worm-like Micelle Based on Double-Tailed Surfactant
by Fanghui Liu, Huiyu Huang, Mingmin Zhang, Meng Mu, Rui Chen and Xin Su
Materials 2025, 18(4), 902; https://doi.org/10.3390/ma18040902 - 19 Feb 2025
Viewed by 227
Abstract
CO2-responsive worm-like micelles (WLMs) are considered promising for applications in smart materials, enhanced oil recovery, and drug delivery because of their reversible and tunable properties. This study presents a novel system of CO2-responsive WLMs, which is constructed using a [...] Read more.
CO2-responsive worm-like micelles (WLMs) are considered promising for applications in smart materials, enhanced oil recovery, and drug delivery because of their reversible and tunable properties. This study presents a novel system of CO2-responsive WLMs, which is constructed using a double-tailed surfactant (DTS). When exposed to CO2, the DTS molecules undergo protonation, resulting in the formation of ultra-long-chain cationic surfactants that self-assemble into worm-like micelles. The zero-shear viscosity of the DTS–CO2 solution achieves approximately 300,000 mPa·s, which is 300,000 times higher than that of pure water. In contrast, the DTS–air solution exhibits a viscosity of only 2 mPa·s. The system retains a viscosity above 100,000 mPa·s across a temperature range of 25–120 °C under a CO2 atmosphere. Moreover, it demonstrates reversible transitions between high- and low-viscosity states without any loss of responsiveness, even after multiple cycles. The critical overlap concentration of the DTS–CO2 micellar system is determined to be 80 mM. This research offers valuable insights into the development of CO2-responsive surfactants, highlighting their potential for designing advanced functional materials. Full article
(This article belongs to the Special Issue Multi-Scale Bionic Materials: Interfacial Design, Effective Fabrication and Functional Application)
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15 pages, 3663 KiB  
Article
Influence of Accelerated Carbonation Conditions on the Physical Properties Improvement of Recycled Coarse Aggregate
by Nasir Mehmood, Pinghua Zhu, Hui Liu, Haichao Li and Xudong Zhu
Materials 2025, 18(4), 901; https://doi.org/10.3390/ma18040901 - 19 Feb 2025
Viewed by 258
Abstract
The preparation of new-generation concrete from recycled coarse aggregate (RA) is an effective way to realize the resource utilization of construction waste. However, loose and porous attached mortar leads to RA showing low-density, high-water absorption, and high crushing value. However, carbonation modification treatment [...] Read more.
The preparation of new-generation concrete from recycled coarse aggregate (RA) is an effective way to realize the resource utilization of construction waste. However, loose and porous attached mortar leads to RA showing low-density, high-water absorption, and high crushing value. However, carbonation modification treatment can effectively improve the performance of RA. This paper studied the effects of carbon dioxide (CO2) concentration, gas pressure, and moisture content on the RA physical properties (apparent density, water absorption, crushing value, and soundness) of waste concrete. The results showed that, when the (CO2) concentration increased from 20% to 60%, the apparent density of RA after carbonation increased by 0.23–0.31%, the water absorption decreased by 0.57–0.93%, the crushing value decreased by 0.36–0.61%, and the soundness decreased by 0.47–0.85%. When the (CO2) concentration was further increased from 60% to 80%, the apparent density of RA after carbonation was increased by 0.04–0.05%, the water absorption was improved by 0.15–0.31%, the crushing value was reduced by 0.06–0.07%, and the soundness was reduced by 0.09–0.11%. During the carbonation modification process, the performance of RA was significantly enhanced when the moisture content was 3.4% and the dissolution of hydration products was accelerated. The diffusion rate of CO2 and the carbonation reaction rate decreased with the high moisture content of RA. As gas pressure increases to 0.01 MPa, the physical properties of RA change significantly, because gas pressure promotes the carbonation reaction between hydration products and CO2 in attached mortar. As the gas pressure increased to 0.5 MPa, RA’s apparent density gradually increased, while its water absorption, crushing value, and stability gradually decreased. The result improved RA’s performance. SEM images show that carbonation modification of RA under different gas pressures increases CaCO3 in attached mortar, filling the Interfacial Transition Zone (ITZ), and decreasing crack width and number. Gas pressure accelerates CO2 diffusion and reaction with hydration products, resulting in narrower ITZ and dense mortar. Full article
(This article belongs to the Special Issue Sustainable and Advanced Cementitious Materials)
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28 pages, 11405 KiB  
Article
Study on Mechanical Properties and Impact Energy Release Characteristics of Skeleton-Structured Al/Ni Reactive Materials
by Zhichao Sun, Yansong Yang, Rui Zhang, Lei Guo, Yuan He, Enliang Liu, Chuanting Wang and Yong He
Materials 2025, 18(4), 900; https://doi.org/10.3390/ma18040900 - 19 Feb 2025
Viewed by 215
Abstract
Reactive materials can be employed to realize the integration of damage element kinetic energy and chemical energy damage, as well as strengthen the destruction ability of warheads. Among them, Al/Ni material has become a research hotspot because of its simple structure, easy process, [...] Read more.
Reactive materials can be employed to realize the integration of damage element kinetic energy and chemical energy damage, as well as strengthen the destruction ability of warheads. Among them, Al/Ni material has become a research hotspot because of its simple structure, easy process, and high reaction heat. In this paper, a skeleton-structured Al/Ni reactive material was successfully prepared. Additionally, both static and dynamic mechanical performance tests were conducted, along with impact experiments in a quasi-sealed chamber. Furthermore, numerical simulations of the mechanical properties of the materials were performed. The results show that the prepared reactive material has a compressive strength of 150 MPa and a tensile strength of 51 MPa, and the numerical simulation results are in good agreement with the experimental data. The impact experiments and product recovery analysis show that the material has a certain energy release ability, and the overpressure can attain 0.081 MPa at a velocity of 1370 m/s in an air atmosphere. However, the overpressure in all experiments under an argon atmosphere is less than 0.02 MPa, which proves that the main reaction under the impact condition is an oxidation reaction rather than a metal intermetallic reaction. The results of this paper provide theoretical support and a data basis for the design of three-dimensional skeletons of reactive materials and the structural optimization and improvement in mechanical properties and have certain guiding significance in the application of Al/Ni reactive materials. Full article
(This article belongs to the Special Issue Progress in Metal Matrix Composites: Design, Processing and Application (2nd Edition))
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17 pages, 6283 KiB  
Article
Thermodynamic Modeling and Experimental Validation for Thermal Beneficiation of Tungsten-Bearing Materials
by Ndue Kanari, Frederic Diot, Chloe Korbel, Allen Yushark Fosu, Eric Allain, Sebastien Diliberto, Eric Serris, Loïc Favergeon and Yann Foucaud
Materials 2025, 18(4), 899; https://doi.org/10.3390/ma18040899 - 19 Feb 2025
Viewed by 320
Abstract
Tungsten (W), a rare metal, is categorized as a Critical and Strategic Raw Material (CRM) by the European Union (EU), with the highest economic importance of all selected CRMs since 2014. Tungsten and its derivatives are extracted from their commercial raw materials, mainly [...] Read more.
Tungsten (W), a rare metal, is categorized as a Critical and Strategic Raw Material (CRM) by the European Union (EU), with the highest economic importance of all selected CRMs since 2014. Tungsten and its derivatives are extracted from their commercial raw materials, mainly wolframite [(Fe,Mn)WO4] and scheelite (CaWO4) ores. Subsequently to mining and mineral processing, the W ore is submitted to thermal treatment and hydrometallurgy under aggressive conditions (high pressure and temperature), which are usually applied for the extraction of tungsten compounds. This paper aims to investigate a thermal route for scheelite processing using various selected chemical agents, resulting in a W-bearing material that is capable of being leached under softer conditions. In this context, a thermodynamic study of the interaction between FeWO4, MnWO4 and CaWO4 and various chemical reagents is described. The thermochemical calculations and data modeling show that, among other considerations, the reaction of CaWO4 with magnesium chloride (MgCl2) can lead to the formation of magnesium tungsten oxide (MgWO4), which appears to be more easily leachable than CaWO4. Experimental tests of the reaction of scheelite with MgCl2 appear to validate the thermodynamic predictions with satisfactory process kinetics at temperatures from 725 to 775 °C. Full article
(This article belongs to the Special Issue Processing of End-of-Life Materials and Industrial Wastes (3rd Edition))
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17 pages, 11707 KiB  
Article
Interfacial Characteristics and Mechanical Properties of TiAl4822/Ti6Al4V Metal–Intermetallic Laminate Composite Prepared Through Vacuum Hot Pressing
by Jianwen Qin, Shouyin Zhang, Zhijian Ma and Baiping Lu
Materials 2025, 18(4), 898; https://doi.org/10.3390/ma18040898 - 19 Feb 2025
Viewed by 355
Abstract
In this work, the TiAl4822/Ti6Al4V metal–intermetallic laminate (MIL) composite was fabricated using vacuum hot pressing (VHP). The interfacial morphologies and mechanical properties of the composites were investigated. No discernible defect was observed in the well-bonded interface region. This interface region comprised two distinct [...] Read more.
In this work, the TiAl4822/Ti6Al4V metal–intermetallic laminate (MIL) composite was fabricated using vacuum hot pressing (VHP). The interfacial morphologies and mechanical properties of the composites were investigated. No discernible defect was observed in the well-bonded interface region. This interface region comprised two distinct areas: the Ti2Al (6 μm) region near the TiAl layer and the Ti3Al (4 μm) region near the Ti6Al4V layer. Electron backscatter diffraction analysis revealed that dynamic recrystallization (DRX) took place at the interface during the hot pressing process. The ductile brittle nature of Ti6Al4V and TiAl4822 layers and the formation of fine grains within the interface are conducive to enhancing toughness and tensile strength. Room temperature tensile testing exhibited that the tensile strength of TiAl4822/Ti6Al4V MIL composite was 636.9 MPa, approximately 225 MPa higher than single TiAl4822 alloy. The Ti6Al4V layer, as well as the formation of fine grain interface, effectively inhibited further propagation of the main crack through crack passivation, crack deflection, and load transformation. The bending strength of the TiAl4822/Ti6Al4V MIL composite was 1114.1 MPa. The fracture toughness of the TiAl4822/Ti6Al4V MIL composite reached 33.15 MPam1/2, which increased by 78.2% compared with single TiAl4822 alloy. Full article
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22 pages, 9353 KiB  
Article
Numerical Investigation of the Axial Compressive Behavior of a Novel L-Shaped Concrete-Filled Steel Tube Column
by Fujian Yang, Yi Bao, Muzi Du and Xiaoshuang Li
Materials 2025, 18(4), 897; https://doi.org/10.3390/ma18040897 - 19 Feb 2025
Viewed by 241
Abstract
A novel L-shaped concrete-filled steel tube (CFST) column is proposed in this study. A finite element model of the column is developed using ABAQUS software to analyze its load transfer mechanism and axial compressive behavior. The effects of factors such as the steel [...] Read more.
A novel L-shaped concrete-filled steel tube (CFST) column is proposed in this study. A finite element model of the column is developed using ABAQUS software to analyze its load transfer mechanism and axial compressive behavior. The effects of factors such as the steel strength, steel tube thickness, support plate configuration, and perforation of the support plates on the compressive performance of the column are investigated. The simulation results reveal that the column exhibits robust axial compressive performance. Increasing the steel strength and incorporating support plates (SP) effectively enhance the column’s compressive bearing capacity and positively influence the bearing capacity coefficient (δ). However, increasing the steel tube thickness results in a reduction in δ, indicating that the rate of increase in the bearing capacity diminishes with increasing thickness. The failure mode is primarily characterized by local buckling in the midsection of the steel tube’s concave corner. Measures such as increasing the steel strength and tube thickness and the use of support plates help to mitigate buckling at the concave corner, improve concrete confinement, and enhance the overall compressive performance of the column. Full article
(This article belongs to the Section Construction and Building Materials)
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10 pages, 8894 KiB  
Communication
Preparation and Performance Optimization of Fe2+:ZnSe Solid Solution by High-Pressure–High-Temperature Method
by Lijuan Wang, Haohao Yang, Shiyun Zheng, Xin Fan, Qiong Gao, Fangbiao Wang, Qi Chen, Peng Liu and Linjun Li
Materials 2025, 18(4), 896; https://doi.org/10.3390/ma18040896 - 19 Feb 2025
Viewed by 335
Abstract
In this paper, high-purity zinc selenide (ZnSe) prepared by the Chemical Vapor Deposition (CVD) method was used as the raw material, and iron ion-doped zinc selenide polycrystals were successfully fabricated through the thermal diffusion method at 1100 °C for 30 h. The results [...] Read more.
In this paper, high-purity zinc selenide (ZnSe) prepared by the Chemical Vapor Deposition (CVD) method was used as the raw material, and iron ion-doped zinc selenide polycrystals were successfully fabricated through the thermal diffusion method at 1100 °C for 30 h. The results showed that iron ions (Fe2+) successfully penetrated into the zinc selenide crystals, but the concentration of iron ions inside the crystals was relatively low, and the crystals exhibited numerous defects. To address this issue, we performed secondary sintering and annealing on the samples under high-temperature and high-pressure (HPHT) conditions, with the annealing temperature range set at 900–1200 °C. The results demonstrated that, under the synergistic effects of high temperature and high pressure, the lattice spacing in the crystals significantly decreased, defects were reduced, the distribution of iron ions became more uniform, and the concentration of iron ions in the central region increased. Additionally, the density and hardness of the samples were significantly improved. The method of secondary sintering under high-temperature and high-pressure provides a novel approach for the preparation of iron ion-doped zinc selenide polycrystalline ceramics, contributing to the enhancement of ceramic properties. Full article
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51 pages, 17258 KiB  
Review
A Review of Simulation Tools Utilization for the Process of Laser Powder Bed Fusion
by Ľuboš Kaščák, Ján Varga, Jana Bidulská, Róbert Bidulský and Tibor Kvačkaj
Materials 2025, 18(4), 895; https://doi.org/10.3390/ma18040895 - 18 Feb 2025
Viewed by 365
Abstract
This review describes the process of metal additive manufacturing and focuses on the possibility of correlated input parameters that are important for this process. The correlation of individual parameters in the metal additive manufacturing process is considered using simulation tools that allow the [...] Read more.
This review describes the process of metal additive manufacturing and focuses on the possibility of correlated input parameters that are important for this process. The correlation of individual parameters in the metal additive manufacturing process is considered using simulation tools that allow the prediction of various defects, thus making the real production process more efficient, especially in terms of time and costs. Special attention is paid to multiple applications using these simulation tools as an initial analysis to determine the material’s behavior when defining various input factors, including the results obtained. Based on this, further procedures were implemented, including real production parts. This review also points out the range of possible variations that simulation tools have, which helps to effectively predict material defects and determine the volume of consumed material, supports construction risk, and other information necessary to obtain a quality part in the production process. From the overview of the application of simulation tools in this process, it was found that the correlation between theoretical knowledge and the definition of individual process parameters and other variables are related and are of fundamental importance for achieving the final part with the required properties. In terms of some specific findings, it can be noted that simulation tools identify adverse phenomena occurring in the production processes and allow manufacturers to test the validity of the proposed conceptual and model solutions without making actual changes in the production system, and they have the measurable impact on the design and production of quality parts. Full article
(This article belongs to the Special Issue Plastic Deformation and Mechanical Behavior of Metallic Materials)
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20 pages, 6306 KiB  
Article
Nanostructured Chromium PVD Thin Films Fabricated Through Copper–Chromium Selective Dissolution
by Stefano Mauro Martinuzzi, Stefano Caporali, Rosa Taurino, Lapo Gabellini, Enrico Berretti, Eric Schmeer and Nicola Calisi
Materials 2025, 18(4), 894; https://doi.org/10.3390/ma18040894 - 18 Feb 2025
Viewed by 258
Abstract
This study investigates the fabrication of nanostructured chromium thin films via selective dissolution of PVD-deposited Cu–Cr thin films. The effects of the deposition parameters on the structural, chemical, and morphological properties of the films are systematically analyzed. Starting from a thin film composed [...] Read more.
This study investigates the fabrication of nanostructured chromium thin films via selective dissolution of PVD-deposited Cu–Cr thin films. The effects of the deposition parameters on the structural, chemical, and morphological properties of the films are systematically analyzed. Starting from a thin film composed of 50 wt.% chromium and 50 wt.% copper, deposited onto a substrate pre-heated to 300 °C, we demonstrate that the following dealloying process carried out in a diluted nitric acid solution yields nanostructured chromium films with high porosity, large surface area, enhanced wettability and neglectable copper content. These findings underline the critical influence of the deposition temperature and alloy composition on achieving optimal film properties. Full article
(This article belongs to the Special Issue Advancements in Thin Film Deposition Technologies)
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18 pages, 7002 KiB  
Article
Influence of Pre-Strain on the Course of Energy Dissipation and Durability in Low-Cycle Fatigue
by Stanisław Mroziński, Michał Piotrowski, Władysław Egner and Halina Egner
Materials 2025, 18(4), 893; https://doi.org/10.3390/ma18040893 - 18 Feb 2025
Viewed by 263
Abstract
The work undertaken in this paper is the comparative analysis of the accumulation of plastic strain energy in the as-received and pre-deformed (overloaded) material states, performed on the example of S420M steel. For this reason, the low-cycle fatigue tests on S420M steel specimens [...] Read more.
The work undertaken in this paper is the comparative analysis of the accumulation of plastic strain energy in the as-received and pre-deformed (overloaded) material states, performed on the example of S420M steel. For this reason, the low-cycle fatigue tests on S420M steel specimens were conducted under controlled deformation conditions, and both as-received (undeformed) and pre-deformed specimens were used in the tests. The results of the low-cycle tests were analyzed in terms of dissipated energy. This study found that pre-straining of S420M steel specimens causes a reduction in the energy of the hysteresis loop at all strain amplitude levels. This results in a slight increase in the fatigue life of pre-strained specimens compared to as-received specimens. Based on the analysis, it was also found that despite the different lifetimes obtained at the same strain amplitude levels, the fatigue characteristics in terms of energy of the as-received and pre-strained samples are statistically the same. Experimental verification of the analytical models used to describe hysteresis loops confirmed their suitability for describing fatigue behavior for specimens made of steel in both the as-received and pre-strained state. Full article
(This article belongs to the Special Issue High-Performance Applications of Advanced Materials: Material Properties, Behaviour Modeling, Optimal Design and Advanced Processes)
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8 pages, 1449 KiB  
Communication
Interface Effects on the Electronic and Optical Properties of Graphitic Carbon Nitride (g-C3N4)/SnS2: First-Principles Studies
by Li-Hua Qu, Yu Wang, Si-Wen Xia, Ran Nie, Le Yin, Chong-Gui Zhong, Sheng-Li Zhang, Jian-Min Zhang and You Xie
Materials 2025, 18(4), 892; https://doi.org/10.3390/ma18040892 - 18 Feb 2025
Viewed by 304
Abstract
Heterojunctions have received much interest as a way to improve semiconductors’ electrical and optical properties. The impact of the interface on the electrical and optical properties of g-C3N4/SnS2 was explored using first-principles calculations in this study. The results [...] Read more.
Heterojunctions have received much interest as a way to improve semiconductors’ electrical and optical properties. The impact of the interface on the electrical and optical properties of g-C3N4/SnS2 was explored using first-principles calculations in this study. The results show that, at the hetero-interface, a conventional type-II band forms, resulting in a lower band gap than that in the g-C3N4 and SnS2 monolayers. When there is no high barrier height, the averaged microscopic and averaged macroscopic potentials can be used to accomplish efficient carrier transformation. Furthermore, the polarization direction affects the absorption spectra. All of these discoveries have significant implications for the development of g-C3N4-based optoelectronics. Full article
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16 pages, 4447 KiB  
Article
Innovative Hemp Shive-Based Bio-Composites, Part II: The Effect of the Phase Change Material (PCM) Additive on Characteristics of Modified Potato Starch Binders
by Laura Vitola, Ina Pundiene, Jolanta Pranckevičienė and Diana Bajare
Materials 2025, 18(4), 891; https://doi.org/10.3390/ma18040891 - 18 Feb 2025
Viewed by 1351
Abstract
This study investigates the effect of phase change materials (PCM) on the properties of modified potato starch binders and hemp shive-based bio-composites, emphasizing their potential for sustainable construction applications. PCM-modified binders have shown reduced viscosity during gelatinization, enhancing their workability and uniformity during [...] Read more.
This study investigates the effect of phase change materials (PCM) on the properties of modified potato starch binders and hemp shive-based bio-composites, emphasizing their potential for sustainable construction applications. PCM-modified binders have shown reduced viscosity during gelatinization, enhancing their workability and uniformity during processing. A microstructural analysis reveals that PCM addition results in a denser and more cohesive binder network, leading to improved adhesion and reduced porosity. A thermal analysis demonstrates a shift to higher decomposition temperatures and a linear increase in specific heat capacity within the PCM phase-change range (20–30 °C), significantly enhancing the thermal storage capacity of the bio-composites. PCM addition improves compressive strength by up to twice, with optimal performance achieved at 8% PCM additive content. The prolonged cooling time, up to three times longer in bio-composites with PCM additive, highlights their effectiveness in thermal regulation. Additionally, bio-composites with a PCM additive exhibits increased bulk density and reduced water swelling, improving dimensional stability. These findings underline the dual benefits of enhanced thermal and mechanical performance in bio-composites with a PCM additive, making them a viable alternative to conventional building materials. Full article
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18 pages, 3619 KiB  
Article
Effect of Grain Size on Thermophysical Properties in Twinning-Induced Plasticity Steel
by Joong-Ki Hwang
Materials 2025, 18(4), 890; https://doi.org/10.3390/ma18040890 - 18 Feb 2025
Viewed by 269
Abstract
This study investigated the thermophysical properties of TWIP steel with respect to grain size. The coefficient of thermal expansion (β) of TWIP steel was approximately 22.4 × 10−6 °C−1, and this value was hardly affected by the grain [...] Read more.
This study investigated the thermophysical properties of TWIP steel with respect to grain size. The coefficient of thermal expansion (β) of TWIP steel was approximately 22.4 × 10−6 °C−1, and this value was hardly affected by the grain size. Therefore the density of TWIP steel was also unaffected by grain size within the tested range. The β in TWIP steel was higher than that of plain carbon steels (13–15 × 10−6 °C−1) such as interstitial free (IF) steel and low-carbon steel, and stainless steels (18–21 × 10−6 °C−1) such as X10NiCrMoTiB1515 steel and 18Cr-9Ni-2.95Cu-0.58Nb-0.1C steel. The specific heat capacity (cp) increased with temperature because the major factor affecting cp is the lattice vibrations. As the temperature increases, atomic vibrations become more active, allowing the material to store more thermal energy. Meanwhile, cp slightly increased with increasing grain size since grain boundaries can suppress lattice vibrations and reduce the material’s ability to store thermal energy. The thermal conductivity (k) in TWIP steel gradually increased with temperature, consistent with the behavior observed in other high-alloy metals. k slightly increased with grain size, especially at lower temperatures, due to the increased grain boundary scattering of free electrons and phonons. This trend aligns with the Kapitza resistance model. While TWIP steel with refined grains exhibited higher yield and tensile strengths, this came with a decrease in total elongation and k. Thus, optimizing grain size to enhance both mechanical and thermal properties presents a challenge. The k in TWIP steel was substantially lower compared with that of plain carbon steels such as AISI 4340 steel, especially at low temperatures, due to its higher alloy content. At room temperature, the k of TWIP steels and plain carbon steels were approximately 13 W/m°C and 45 W/m°C, respectively. However, in higher temperature ranges where face centered cubic structures are predominant, the difference in k of the two steels became less pronounced. At 800 °C, for example, TWIP and plain carbon steels exhibited k values of approximately 24 W/m°C and 29 W/m°C, respectively. Full article
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25 pages, 11202 KiB  
Article
Investigation of Fracture Characteristics and Energy Evolution Laws of Model Tunnels with Different Shapes Subjected to Impact Load
by Fukuan Nie, Xuepeng Zhang, Lei Zhou, Haohan Wang, Jian Hua, Bang Liu and Bo Feng
Materials 2025, 18(4), 889; https://doi.org/10.3390/ma18040889 - 18 Feb 2025
Viewed by 312
Abstract
To investigate dynamic fracture characteristics and failure behavior of different sections of tunnel surrounding rock mass, six kinds of model tunnels were fabricated using green sandstone, and impact tests were performed using a split Hopkinson pressure bar system. The dynamic compressive strength and [...] Read more.
To investigate dynamic fracture characteristics and failure behavior of different sections of tunnel surrounding rock mass, six kinds of model tunnels were fabricated using green sandstone, and impact tests were performed using a split Hopkinson pressure bar system. The dynamic compressive strength and energy change behaviors of samples comprising different-shaped tunnels were assessed, and crack propagation paths were analyzed employing a digital image correlation method. Numerical calculations were carried out using the software LS-DYNA (v. 2021R1), and the dynamic stress concentration factors of different model tunnel samples were determined. The results of the research indicated that the shape of the tunnel affected the dynamic compressive strength. The elliptical tunnel had the smallest percentage of dissipated energy, and the three-centered circular tunnel had the largest percentage of dissipated energy. The maximum tensile stress concentration factor in the model tunnels consistently occurred at the top or bottom; so, the locations of initiation were most commonly at the bottoms and tops of the tunnels. Sample failure resulted from a combination of tensile and shear cracks, with the failure mode being primarily tensile-dominated. Finally, the inverted arch had an obvious alleviating action on the stress concentration phenomenon at the bottom of the three-centered circle. Full article
(This article belongs to the Special Issue Dynamic Mechanical Behavior and Damage and Fracture Mechanisms of Geotechnical Engineering Materials)
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16 pages, 36325 KiB  
Article
Effect of Annealing in Air on the Structural and Optical Properties and Efficiency Improvement of TiO2/CuxO Solar Cells Obtained via Direct-Current Reactive Magnetron Sputtering
by Grzegorz Wisz, Maciej Sibiński, Mirosław Łabuz, Piotr Potera, Dariusz Płoch, Mariusz Bester and Rostyslav Yavorskyi
Materials 2025, 18(4), 888; https://doi.org/10.3390/ma18040888 - 18 Feb 2025
Viewed by 395
Abstract
In this study, four various titanium dioxide/cuprum oxide (TiO2/CuxO) photovoltaic structures deposited on glass/indium tin oxide (ITO) substrates using the direct-current (DC) reactive magnetron sputtering technique were annealed in air. In our previous work, the deposition parameters for different [...] Read more.
In this study, four various titanium dioxide/cuprum oxide (TiO2/CuxO) photovoltaic structures deposited on glass/indium tin oxide (ITO) substrates using the direct-current (DC) reactive magnetron sputtering technique were annealed in air. In our previous work, the deposition parameters for different buffer layer configurations were first optimized to enhance cell fabrication efficiency. In this paper, the effects of post-deposition annealing at 150 °C in air on the optical properties and I-V characteristics of the prepared structures were examined. As a result, significant changes in optical properties and a meaningful improvement in performance in comparison to unannealed cells were observed. Air annealing led to an increase in the reflection coefficient of the TiO2 layer for three out of four structures. A similar increase in the reflection of the CuxO layer occurred after heating for two out of four structures. Transmission of the TiO2/CuxO photovoltaic structures also increased after heating for three out of four samples. For two structures, changes in both transmission and reflection resulted in higher absorption. Moreover, annealing the as-deposited structures resulted in a maximum relative increase in open-circuit voltage (Voc) by 294% and an increase in short-circuit current (Isc) by 1200%. The presented article gives some in-depth analysis of these reported changes in character and origin. Full article
(This article belongs to the Special Issue Advances in Solar Cell Materials and Structures—Second Edition)
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15 pages, 4184 KiB  
Article
Photocatalysis of Methyl Orange (MO), Orange G (OG), Rhodamine B (RhB), Violet and Methylene Blue (MB) Under Natural Sunlight by Ba-Doped BiFeO3 Thin Films
by Abderrahmane Boughelout, Abdelmadjid Khiat and Roberto Macaluso
Materials 2025, 18(4), 887; https://doi.org/10.3390/ma18040887 - 18 Feb 2025
Viewed by 332
Abstract
We present structural, morphological, optical and photocatalytic properties of multiferroic Bi0.98Ba0.02FeO3 (BBFO2) perovskite thin films prepared by a combined sol–gel and spin-coating method. X-ray diffraction (XRD) analysis revealed that all the perovskite films consisted of the stable polycrystalline [...] Read more.
We present structural, morphological, optical and photocatalytic properties of multiferroic Bi0.98Ba0.02FeO3 (BBFO2) perovskite thin films prepared by a combined sol–gel and spin-coating method. X-ray diffraction (XRD) analysis revealed that all the perovskite films consisted of the stable polycrystalline rhombohedral phase structure (space group R3c) with a tolerance factor of 0.892. By using Rietveld refinement of diffractogram XRD data, crystallographic parameters, such as bond angle, bond length, atom position, unit cell parameters, and electron density measurements were computed. Scanning electron microscopy (SEM) allowed us to assess the homogeneous and smooth surface morphology of the films with a small degree of porosity, while chemical surface composition characterization by X-ray photoelectron spectroscopy (XPS) showed the presence of Bi, Fe, O and the doping element Ba. Absorption measurements allowed us to determine the energy band gap of the films, while photoluminescence measurements have shown the presence of oxygen vacancies, which are responsible for the enhanced photocatalytic activity of the material. Photocatalytic degradation experiments of Methylene Blue (MB), Methyl orange (MO), orange G (OG), Violet and Rhodamine B (RhB) performed on top of BBFO2 thin films under solar light showed the degradation of all pollutants in varying discoloration efficiencies, ranging from 81% (RhB) to 54% (OG), 53% (Violet), 47% (MO) and 43% (MB). Full article
(This article belongs to the Special Issue Halide Perovskite Crystal Materials and Optoelectronic Devices)
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12 pages, 5101 KiB  
Article
Microstructure and Mechanical Properties of In-Doped Low-Temperature SnPb Solders
by Xiaochen Xie, Pengrong Lin, Binhao Lian, Shimeng Xu, Yong Wang, Shuyuan Shi, Leqi Fu and Xiuchen Zhao
Materials 2025, 18(4), 886; https://doi.org/10.3390/ma18040886 - 18 Feb 2025
Viewed by 320
Abstract
In this paper, In was introduced into SnPb eutectic solder to develop a new low-temperature solder for three-dimensional packaging technology. SnPbIn solders containing 5, 10, 13, 15 and 17 wt.% In were prepared through vacuum induction melting. The effect of the addition of [...] Read more.
In this paper, In was introduced into SnPb eutectic solder to develop a new low-temperature solder for three-dimensional packaging technology. SnPbIn solders containing 5, 10, 13, 15 and 17 wt.% In were prepared through vacuum induction melting. The effect of the addition of In on the microstructure and thermal and mechanical properties of the SnPbIn solders was investigated. The results showed that the SnPb eutectic solder consisted of Sn(ss) and Pb(ss), but when the In content was higher than 5 wt.%, the SnPbIn solder included Sn(ss) and Pb(ss) and a new InSn4 phase. Solid dissolution of the In element into Sn(ss) and Pb(ss) preferentially occurred. The melting points of the SnPbIn solders gradually decreased with the increasing addition of the In element. The melting point of the Sn-Pb-13In solder decreased to 150.5 °C, which met the requirements of 2.5D packaging. But the cast Sn-Pb-5In solder reached the best tensile strength of 48.8 MPa and elongation of 27.3%. Super-plasticity occurred in the cold-rolled SnPbIn, while the 59.9Sn35.1 Pb5In solder achieved elongation of 382.0% and 408.6%, respectively, at deformation of 70% and 90%. The super-plasticity originated from the recrystallization behavior and soft orientation. Full article
(This article belongs to the Special Issue Advances in Multicomponent Alloy Design, Simulation and Properties)
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