Materials

16 pages, 19815 KiB

Open AccessArticle

Controlling M-A Constituents and Bainite Morphology for Enhanced Toughness in Isothermally Transformed Low-Carbon Ni-Cr-Mo Steel

by Guang Ji, Dianfu Fu, Guangyuan Wang, Kaihao Guo, Xiaobing Luo, Feng Chai and Tao Pan

Materials 2025, 18(9), 1945; https://doi.org/10.3390/ma18091945 (registering DOI) - 24 Apr 2025

Abstract

The isothermal bainitic transformation kinetics, microstructure, and mechanical properties of the quenched low-carbon high-strength steel have been investigated via dilatometric measurements, microstructural characterization, and mechanical tests. The results show that the pre-transformed isothermal bainite promotes martensitic transformation, increasing the martensitic transformation temperature, and [...] Read more.

The isothermal bainitic transformation kinetics, microstructure, and mechanical properties of the quenched low-carbon high-strength steel have been investigated via dilatometric measurements, microstructural characterization, and mechanical tests. The results show that the pre-transformed isothermal bainite promotes martensitic transformation, increasing the martensitic transformation temperature, and enhancing the transformation rate. The microstructure of the 400 °C isothermal steel consists predominantly of lath bainite ferrite with dot/slender M-A constituents, whereas the steel treated at 450 °C contains a combination of martensite/lath bainite and granular bainite. The presence of massive M-A constituents contributes to brittle fracture as these constituents tend to promote crack initiation. Hence, the 450 °C treatment, which leads to the formation of massive M-A constituents, induces brittleness, while the finer M-A constituents formed at 400 °C exert minimal influence on the toughness and result in a more stable microstructure owing to their small size and the surrounding fine lath microstructure. The differences in microstructure and properties between the steels treated at 400 °C and 450 °C illustrate the importance of controlling the quenching cooling rate in the high-temperature bainitic transformation region during thick plate quenching processes. Full article

(This article belongs to the Special Issue Microstructure, Mechanical Properties and Wear Performance of High-Strength Steels)

11 pages, 2292 KiB

Open AccessArticle

Clinical Adjustment of Zirconia-Reinforced Lithium Silicate and Lithium Disilicate Restorations Should Be Performed Before Crystallization

by Kusai Baroudi, Nathália Ribeiro de Almeida, Laura Salerno de Abreu, Vinícius Felipe Wandscher, Nathalia de Carvalho Ramos, Vivek Padmanabhan, Caroline Andrade Bucholz and Marina Amaral

Materials 2025, 18(9), 1944; https://doi.org/10.3390/ma18091944 - 24 Apr 2025

Abstract

The objective of this study was to evaluate the biaxial flexural strength of zirconia-reinforced lithium silicate (ZLS, eMax CAD, Ivoclar Vivadent) and lithium disilicate (LDS, Suprinity, VITA)) discs after abrasion with a diamond tip, before or after crystallization of the ceramic. Discs of [...] Read more.

The objective of this study was to evaluate the biaxial flexural strength of zirconia-reinforced lithium silicate (ZLS, eMax CAD, Ivoclar Vivadent) and lithium disilicate (LDS, Suprinity, VITA)) discs after abrasion with a diamond tip, before or after crystallization of the ceramic. Discs of 1.2 × 15 mm dimensions were fabricated. The samples were separated into two groups: AC—abrasion with a diamond tip before material crystallization, and CA—material crystallization and subsequent abrasion with a diamond tip (n = 15). The initial roughness was measured before abrasion/crystallization, and final measurement was performed after abrasion/crystallization/polishing. The abraded surface was placed downward during the biaxial flexural strength test, and the data were recorded. The final roughness was significantly higher compared to the initial roughness in all groups. The ZLS-AC and LDS-AC groups (both materials with abrasion prior to material crystallization) showed higher biaxial flexural strength values than groups that underwent abrasion before crystallization. This study concluded that the clinical adjustment performed by abrasion with the diamond tip of glass ceramics lithium disilicate and zirconia-reinforced lithium silicate carried out prior to crystallization favored the resistance of the ceramics. Full article

(This article belongs to the Special Issue Characteristics of Dental Ceramics)

21 pages, 1413 KiB

Open AccessArticle

The Optimization Study of Karst-Filling Clay-Cement Grout Based on Orthogonal Experiment and Regression Analysis

by Wenqin Yan, Chao Deng, Yuehui Cai, Aikun Chu, Shifan Shen and Xuanyu Wu

Materials 2025, 18(9), 1943; https://doi.org/10.3390/ma18091943 - 24 Apr 2025

Abstract

During shield tunnel construction, karst development along the tunnel axis and in the surrounding area frequently poses a significant threat to engineering safety. To address this challenge, this study proposes multiple grouting systems and systematically analyzes the key mechanical properties of five grout [...] Read more.

During shield tunnel construction, karst development along the tunnel axis and in the surrounding area frequently poses a significant threat to engineering safety. To address this challenge, this study proposes multiple grouting systems and systematically analyzes the key mechanical properties of five grout formulations through orthogonal experiments, identifying the optimal formulations for engineering applications. A predictive model was established using linear regression, and its accuracy was validated through independent single-factor experiments. The results indicate the following: (1) Water content is the primary factor influencing fluidity, with its significance varying by system composition. The lake mud-cement grout exhibits the highest compressive pstrength. Moderate sand addition enhances strength, but excessive amounts significantly reduce fluidity. Additives demonstrate system dependency: HY-4 effectively improves fluidity, while sodium silicate significantly increases strength but reduces fluidity. (2) The developed model demonstrates good goodness of fit, with coefficients of determination (R²) ranging from 0.74 to 0.95, without significant autocorrelation or multicollinearity. Validation experiments confirm the model’s high predictive accuracy, with overall trends consistent with the measured data. (3) The lake mud-cement grout (A3B1C3) is recommended for reinforcement projects prioritizing stability, achieving a 28-day compressive strength of 4.74 MPa. The on-site wet clay-cement grout (A2B3C1) is suitable for high-permeability formations, with a strength of 1.1 MPa and a fluidity of 292.5 mm, both exceeding standard requirements. The findings provide optimized formulations and theoretical references for grouting reinforcement in karst tunnel projects. Full article

(This article belongs to the Special Issue Recent Advances in Sustainability, Characterization, and Performance of Cementitious Composites)

16 pages, 2282 KiB

Open AccessArticle

Experimental Study on the Effects of Thermal Cycling and Ultraviolet Irradiation on Stable Characteristics of Carbon Fiber/Bismaleimide Polymer Composite Shells

by Zheng Zhang, Xinyue Ji, Min Sun, Libin Xiong, Guang Zhang, Wenjie Ding, Jiquan Li and Shaofei Jiang

Materials 2025, 18(9), 1942; https://doi.org/10.3390/ma18091942 - 24 Apr 2025

Abstract

Carbon fiber/epoxy composites are widely used in aerospace due to their strength and ease of fab weatherrication, but they suffer from glass transition at high temperatures. In contrast, carbon fiber/bismaleimide composites exhibit superior thermal stability, irradiation resistance, and toughness. This study investigates the [...] Read more.

Carbon fiber/epoxy composites are widely used in aerospace due to their strength and ease of fab weatherrication, but they suffer from glass transition at high temperatures. In contrast, carbon fiber/bismaleimide composites exhibit superior thermal stability, irradiation resistance, and toughness. This study investigates the effects of thermal cycling and UV irradiation on carbon fiber/bismaleimide composite shells. Anti-symmetric shells with varying ply angles were tested under two-point tensile loading. Results show that these shells maintain stability between −70 °C and 180 °C, outperforming epoxy-based composites. This research offers valuable insights for aerospace applications of such bistable shells under thermal and UV aging conditions. Full article

(This article belongs to the Topic Advanced Carbon Fiber Reinforced Composite Materials, Volume II)

21 pages, 9254 KiB

Open AccessArticle

Effect of Heat Treatment on the Grain Boundary Character Distribution and Bending Properties of Fine-Grained Phosphorus Bronze

by Zhongping Chen, Yang Yang, Huafen Lou and Hu Wang

Materials 2025, 18(9), 1941; https://doi.org/10.3390/ma18091941 - 24 Apr 2025

Abstract

Grain boundary engineering (GBE) has been widely used to modify grain boundary (GB) networks to improve GB-related properties in polycrystalline materials. With the development of miniaturized and lightweight terminal connectors comes a greater demand for phosphorus bronze. A fine grain size and excellent [...] Read more.

Grain boundary engineering (GBE) has been widely used to modify grain boundary (GB) networks to improve GB-related properties in polycrystalline materials. With the development of miniaturized and lightweight terminal connectors comes a greater demand for phosphorus bronze. A fine grain size and excellent GB characteristics are the keys to synergistically enhancing mechanical strength and bending workability. In this study, the effects of the annealing temperature on the grain boundary character distribution (GBCD) optimization and the bending properties of phosphorus bronze were studied by means of electron backscatter diffraction and a 90° bending test. The results show that the deformed microstructure of the as-received material recrystallizes upon annealing at 400 °C for 1 h. The average grain size is 1.6 μm, and a large number of special boundaries (SBs) are present, accounting for 71.5% of all GBs. Further, the incoherent Σ3, Σ9, and Σ27 boundaries are the most abundant, effectively disrupting the network connectivity of random high-angle grain boundaries. The grain size gradually increases with the annealing temperature increase. The fractions of the Σ9 and Σ27 boundaries gradually decrease. Although the proportion of SBs further increases at higher temperatures, most SBs at these temperatures are coherent Σ3 boundaries that do not contribute to the direct optimization of GBCD. Moreover, in the absence of a significant difference in tensile strength, the GBCD-optimized fine-grained sample demonstrates smooth surfaces without orange peel effects when bent at 90° with R/t = 0 in the bad way. This improvement is attributed to the uniform deformation of fine grains and special boundaries, which enhances the bending workability of the GBCD-optimized fine-grained strips. Full article

(This article belongs to the Section Advanced Materials Characterization)

16 pages, 5511 KiB

Open AccessArticle

Influence and Mechanism of Coal Gangue Sand on the Properties and Microstructure of Shotcrete Mortar

by Yong Cui

Materials 2025, 18(9), 1940; https://doi.org/10.3390/ma18091940 - 24 Apr 2025

Abstract

Coal gangue, a fine aggregate for the preparation of shotcrete mortar, is a cost-effective approach for the resource utilization of coal gangue. This study employed a mortar setting time tester, electronic universal testing machine, water absorption tester, nitrogen adsorption–desorption instrument (BET), X-ray diffraction [...] Read more.

Coal gangue, a fine aggregate for the preparation of shotcrete mortar, is a cost-effective approach for the resource utilization of coal gangue. This study employed a mortar setting time tester, electronic universal testing machine, water absorption tester, nitrogen adsorption–desorption instrument (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and life cycle assessment (LCA) to investigate the effects and mechanisms of replacing natural sand with coal gangue sand (0–100%) under water-to-binder ratios of 0.4 and 0.55 on the macroscopic properties, microstructure, and environmental impact of shotcrete mortar. The results showed that the porous nature of coal gangue sand increased the porosity of shotcrete mortar and reduced its compressive strength. However, its water absorption effectively decreased the effective water-to-binder ratio, significantly shortening the initial setting time. At a water-to-binder ratio of 0.55, as the replacement ratio of coal gangue sand increased from 0% to 100%, the porosity of shotcrete mortar increased by approximately 30%, the compressive strength decreased by about 40%, and the initial setting time was shortened by 57%. When the water-to-binder ratio was reduced to 0.4 and the replacement ratio of coal gangue sand was 50%, the shotcrete mortar met the application requirements of M20 shotcrete mortar, with an initial setting time of less than 12 min and a compressive strength of over 23 MPa after 28 days of water curing. Microstructural analysis revealed that the absorbed water in coal gangue sand played an internal curing role during cement hardening, improving the compactness of the interfacial transition zone. Environmental assessment results indicated that, under the same strength conditions, the life cycle environmental impact of coal gangue sand shotcrete mortar was approximately 70% lower than that of natural sand shotcrete mortar. This study provides a theoretical basis for the efficient resource utilization of coal gangue and the preparation of low-carbon shotcrete mortar. Full article

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

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26 pages, 2047 KiB

Open AccessArticle

Simulation and Structural Optimization of an Eccentric Rotor Extruder Feeding Section

by Jinhui Jiang, Yanhong Feng, Shuo Gao, Wenqiang Yan, Xiaochun Yin and Guizhen Zhang

Materials 2025, 18(9), 1939; https://doi.org/10.3390/ma18091939 - 24 Apr 2025

Abstract

The eccentric rotor extruder (ERE) is polymer processing equipment that exhibits excellent processing capabilities for materials with extremely high viscosity, which are difficult to plastically deform and transport efficiently. However, the mass transfer mechanism in the solid conveying section of this new device [...] Read more.

The eccentric rotor extruder (ERE) is polymer processing equipment that exhibits excellent processing capabilities for materials with extremely high viscosity, which are difficult to plastically deform and transport efficiently. However, the mass transfer mechanism in the solid conveying section of this new device is fundamentally different from that of traditional extruders, and no related research has been reported. This study uses discrete element method (DEM) simulation technology to model the solid conveying process of the ERE. By visualizing the positive displacement conveying process, and with an analysis of the output parameters, the study clarifies the mass transfer principles and quantifies the conveying capacity, providing guidance for optimizing the extruder design. The simulation results show that the ERE exhibits positive displacement conveying characteristics, with the conveying process achieved by the forward movement of the cavities (closed cavities between the rotor and stator) in a helical manner. However, differences in the dual-cavity (two types of cavities) feeding process and low fill level can lead to significant fluctuations in extrusion output and reduced conveying capacity. To address these issues, an improvement scheme for the dual-cavity feed opening is proposed, with feed openings designed with different opening lengths. Then, by analyzing the particle coordinate data from the simulation output, the conveying capacities of different feed opening structures are quantified and optimized. Finally, experimental and simulation verification results indicate that the optimized structure significantly improves the issues of uneven filling and low fill level, with good correspondence between the simulation and experimental results. Simulation results show that, compared with the original structure, the optimized dual-feed opening structure increases the feed capacity from 3953 particles per cavity to 5132 particles per cavity, an improvement of 29.8%, and it achieves balanced filling between the two cavities. Experimental validation indicates that the UPE4040 output can be increased from 165.3 g/min with structure op-00 to 231.7 g/min with the optimized structure op-05. Full article

23 pages, 11717 KiB

Open AccessArticle

Degradation Susceptibility of Al-2.18Mg-1.92Li Alloy in Severe Environmental Conditions

by Franjo Kozina, Zdenka Zovko Brodarac, Mitja Petrič and Barbara Šetina Batič

Materials 2025, 18(9), 1938; https://doi.org/10.3390/ma18091938 (registering DOI) - 24 Apr 2025

Abstract

Due to the specific application of aluminum–magnesium–lithium (Al-Mg-Li) alloys in the transportation industry, it is necessary to consider the influence of microstructure development on material degradation under severe environmental conditions. This degradation was simulated according to the standard test method ASTM G34-01 (2018) [...] Read more.

Due to the specific application of aluminum–magnesium–lithium (Al-Mg-Li) alloys in the transportation industry, it is necessary to consider the influence of microstructure development on material degradation under severe environmental conditions. This degradation was simulated according to the standard test method ASTM G34-01 (2018) on a newly designed and synthesized Al-2.1Mg-1.92Li alloy in the as-cast condition. The degradation susceptibility of the alloy was estimated by measuring the changes in the sample mass and microhardness, and the pH and chemical composition of the environment with respect to the exposure time. The influence of the microstructure constituents on the degradation of the alloy was determined using metallographic analysis of the exposed surface and cross-section of the samples after testing. During the degradation, dealloying of the α_Al matrix through Li, Mg and Al component dissolution resulted in a decrease in the mass of the samples, an increase in the pH of the environment and changes in its chemical composition. This observation was also confirmed by the results of the metallographic analysis. The degradation involved the formation of cavities around the Al₈Mg₅ (β) and Al₂LiMg (T) intermetallic phases through an anodic dissolution mechanism. The increase in microhardness values after exposure indicated an increase in the stress around the degradation front due to the wedge effect of the degradation products. The results of the investigation support the potential application of the synthesized Al-2.1Mg-1.92Li alloy under the severe environmental conditions defined by the ASTM G34-01 (2018) standard. Full article

(This article belongs to the Special Issue Advances in Corrosion and Protection of Passivating Metals and Alloys)

12 pages, 4423 KiB

Open AccessArticle

Enhanced Energy Storage Properties of the Relaxor and Antiferroelectric Crossover Ceramic Enabled by a High Entropy Design

by Yinghao Li, Wei Xiong, Xuefan Zhou, Hang Luo, Ru Guo and Dou Zhang

Materials 2025, 18(9), 1937; https://doi.org/10.3390/ma18091937 - 24 Apr 2025

Abstract

In this work, we introduce a high entropy effect in designing a relaxor ferroelectric (RFE)–antiferroelectric (AFE) crossover ceramic by incorporating a high entropy relaxor-like oxide (Pb_0.25Ba_0.25Sr_0.25Ca_0.25)TiO₃ with antiferroelectric NaNbO₃. The results show [...] Read more.

In this work, we introduce a high entropy effect in designing a relaxor ferroelectric (RFE)–antiferroelectric (AFE) crossover ceramic by incorporating a high entropy relaxor-like oxide (Pb_0.25Ba_0.25Sr_0.25Ca_0.25)TiO₃ with antiferroelectric NaNbO₃. The results show that the relaxor ferroelectricity of the system is enhanced with increasing NaNbO₃, and when the new composition reaches the highest configurational entropy, stable energy storage properties can be achieved. This is enabled by a high breakdown strength due to the small grain size and stable slim ferroelectric hysteresis loop with high efficiency due to entropy-stabilized short-range ordered polar nanoregions (PNRs). These findings showcase the potential of this strategy for exploiting new compositions of high-performance electrostatic capacitors. Full article

(This article belongs to the Special Issue Advanced Science and Technology of High Entropy Materials)

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14 pages, 23442 KiB

Open AccessArticle

Effect of Co and Al Content on CrFeNiMo-System High Entropy Alloys Produced by Mechanical Alloying

by Laura Elena Geambazu, Ciprian Alexandru Manea, Ileana Mariana Mateș, Delia Pătroi, Gabriela Beatrice Sbârcea, Eugen Manta and Augustin Semenescu

Materials 2025, 18(9), 1936; https://doi.org/10.3390/ma18091936 - 24 Apr 2025

Abstract

This study aims to investigate the Co content on a Co_xCrFeNiMo (x = 0; 0.5) high entropy alloy (HEA) but also the effects of replacing the Co element with Al in terms of single-phase structure forming, processing behavior, and microstructural characteristics [...] Read more.

This study aims to investigate the Co content on a Co_xCrFeNiMo (x = 0; 0.5) high entropy alloy (HEA) but also the effects of replacing the Co element with Al in terms of single-phase structure forming, processing behavior, and microstructural characteristics when being processed by mechanical alloying with a planetary ball mill. Recent HEA-related research aimed toward identifying the effect that certain alloying elements in different concentrations influence the microstructure and properties but also regulate their composition. HEAs present promising properties (e.g., corrosion and wear resistance) being applicable in domains that require protection against harsh environmental conditions, benefiting from the specific core effects of this type of material. To obtain a high alloying and homogenization degree, for this research, mechanical alloying was selected for processing the mixtures, with the aid of N-Heptane as a process control agent (PCA). The mixtures were monitored in terms of alloying degree evolution, elemental distribution, particle morphology, crystalline structure, and also technological characterization (packing ratio, free flow, and slope angle). The results indicated that a high degree of alloying was obtained after 30 h of solid-state processing, with notable crystallization of two major phases FCC and BCC identified confirming the HEA phase stability calculations. Full article

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11 pages, 8107 KiB

Open AccessArticle

Recovery of Valuable Materials Based on Pb and Zn in the Hydrometallurgical Processing of Copper Shaft Furnace Dust

by Martina Laubertová, Martin Sisol, Jaroslav Briančin, Jarmila Trpčevská and Michaela Ružičková

Materials 2025, 18(9), 1935; https://doi.org/10.3390/ma18091935 - 24 Apr 2025

Abstract

Copper shaft furnace (CSF) dust containing valuable metals with a composition of 44.02% Zn and 14.57% Pb, in the form of oxides (PbO and ZnO), was used for leaching in 1 mol/L sodium hydroxide lixiviant at a temperature of 80 °C. The leaching [...] Read more.

Copper shaft furnace (CSF) dust containing valuable metals with a composition of 44.02% Zn and 14.57% Pb, in the form of oxides (PbO and ZnO), was used for leaching in 1 mol/L sodium hydroxide lixiviant at a temperature of 80 °C. The leaching efficiency for lead removal was 98%. The leaching of CSF dust in sodium hydroxide was thermodynamically studied using Pourbaix diagrams for the Pb/Zn/-Na–H₂O system at temperatures of 25 °C and 80 °C. A suitable precipitating agent was 0.5 mol/L sulfuric acid at pH 3. The formation of lead sulfate as the final product was confirmed by SEM, EDX, and XRD analysis. Although increasing the temperature reduced the aging time required for the precipitation, it did not affect the amount of lead precipitated. The solution, after lead precipitation and containing zinc (Zn²⁺), was further treated with ammonium carbonate for zinc precipitation. Various analytical methods, including SEM, EDX, XRD, XRF, and AAS, were used to analyze the input samples and the final products obtained after alkali leaching of CSF dust and lead and zinc precipitation. Full article

(This article belongs to the Special Issue Advances in Process Metallurgy and Metal Recycling)

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17 pages, 25502 KiB

Open AccessArticle

In Situ EBSD Study of Deformation Behavior at Grain Scale of Inconel 718 Alloy During Tensile Test at 650 °C

by Lijun Sang, Junxia Lu, Xiaopeng Cheng, Yuefei Zhang and Ze Zhang

Materials 2025, 18(9), 1934; https://doi.org/10.3390/ma18091934 - 24 Apr 2025

Abstract

In order to clarify the deformation mechanism of Inconel 718 (IN718) alloy at the grain scale during tensile deformation, the deformation behaviors of IN718 alloy were investigated at 650 °C using an in situ electron backscatter diffraction (EBSD) tensile testing method. The evolution [...] Read more.

In order to clarify the deformation mechanism of Inconel 718 (IN718) alloy at the grain scale during tensile deformation, the deformation behaviors of IN718 alloy were investigated at 650 °C using an in situ electron backscatter diffraction (EBSD) tensile testing method. The evolution of grain morphology, crystallographic orientation, activated slip systems, grain boundaries evolution, and strain-induced misorientation were systematically analyzed during the tensile test. The results showed that the grains were elongated along the tensile direction, and the grain boundaries also became significantly curved. Meanwhile, the EBSD studies illustrated that the changes in local misorientation within individual grains were non-uniform and generally began at the grain boundaries. The low-angle grain boundaries (LAGBs) were first formed near the high-angle grain boundaries (HAGBs) and gradually expanded into the interior of the grains. The activation of the slip system and the Schmid factor were characterized and calculated based on the slip traces on the deformed grain surface. The evolution of local strain within the grains was evidenced by a kernel average misorientation (KAM) map. Finally, the plastic deformation mechanism at the grain scale was discussed in detail based on our experimental results. Full article

(This article belongs to the Special Issue Mechanical Properties and Strengthening Mechanism of New Superalloys)

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27 pages, 11587 KiB

Open AccessArticle

Dynamics Analysis of Elastic Ring-Type Extruded Oil Film Damper Considering Time-Varying Characteristics

by Haibiao Zhang, Fuhua Liu, Tao Liu and Qingshan Wang

Materials 2025, 18(9), 1933; https://doi.org/10.3390/ma18091933 - 24 Apr 2025

Abstract

The elastic ring squeeze film damper (ERSFD), due to its compact structure and excellent mechanical properties, has been increasingly applied in various types of combination bearings for aero-engines. During operation, the force state of the elastic ring varies with different precession angles of [...] Read more.

The elastic ring squeeze film damper (ERSFD), due to its compact structure and excellent mechanical properties, has been increasingly applied in various types of combination bearings for aero-engines. During operation, the force state of the elastic ring varies with different precession angles of the journal, leading to changes in the stiffness of the elastic ring. This study, based on a bidirectional fluid–structure interaction (FSI) theory, analyzes the deformation and stiffness of the elastic ring under different contact conditions. The time-varying stiffness curve of the elastic ring is obtained, and the influence of various parameters on its time-varying stiffness characteristics is further investigated. An equivalent stiffness method for the elastic ring is proposed, which improves accuracy by more than 3% at low speeds compared to traditional methods. Using this equivalent method, the effects of parameters such as the number of ring protrusions, protrusion width, protrusion angle, elastic ring thickness, and oil film eccentricity on the pressure distribution of the inner and outer oil films are analyzed. The results indicate that an increase in the number of elastic rings, protrusion width, axial length, and ring thickness leads to a rise in stiffness, with the number of protrusions having the strongest effect and the axial length having the weakest effect. Additionally, as the number of protrusions, protrusion width, and protrusion angle increase, both the damping and stiffness of the inner and outer oil films decrease by approximately 10%, with a more significant impact on the outer oil film than on the inner oil film. When the axial length and oil film eccentricity increase, both the damping and stiffness of the inner and outer oil films also increase, with the inner oil film being highly sensitive to eccentricity. However, excessive eccentricity enhances the nonlinearity of the oil film. The findings of this study provide a theoretical foundation for the design, application, and maintenance of combination bearings incorporating elastic ring squeeze film dampers. Full article

(This article belongs to the Special Issue Dynamic Behavior of Advanced Materials and Structures (Second Edition))

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22 pages, 6315 KiB

Open AccessArticle

Experimental and Numerical Analysis of Rotary Friction Welding for Al-Cu Joints: Effects of Friction Time on Plastic Deformation and Joint Integrity

by Nada Ratković, Dušan Arsić, Ružica R. Nikolić, Marko Delić, Živana Jovanović Pešić, Vesna Mandić and Jana Pastorková

Materials 2025, 18(9), 1932; https://doi.org/10.3390/ma18091932 - 24 Apr 2025

Abstract

The principles of the friction welding (FW) process of the two different non-ferrous metals, aluminum and copper, are presented in this paper. Considering that the bimetallic Al-Cu joints find applications in electrical engineering, as well as in other industrial fields, the basic characteristics [...] Read more.

The principles of the friction welding (FW) process of the two different non-ferrous metals, aluminum and copper, are presented in this paper. Considering that the bimetallic Al-Cu joints find applications in electrical engineering, as well as in other industrial fields, the basic characteristics and compatibility of these metals are discussed, along with the influence of various parameters on the properties of their friction welded joints. The experimental study involved rotation friction welding (RFW), which was used to weld aluminum and copper samples. The samples were monitored for shortening due to the applied deformation, as well as the size of the formed mushroom. Then, the central part of the welded joint was cut from the welded samples to determine the hardness and microstructure of the joint. At the end of the research, the possibility of applying software for the design of a numerical model for analysis of the possibility of joining aluminum and copper, with the same input parameters as those used in the experiment, was considered. The numerical simulation exhibited a high agreement with the experimental results. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys (Second Edition))

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16 pages, 5362 KiB

Open AccessArticle

Study on Mass and Performance Deterioration of Concrete Under Multiple Corrosive Environments

by Haicheng Yang, Weifeng Liu, Hongfa Yu, Wei Wang and Haiyan Ma

Materials 2025, 18(9), 1931; https://doi.org/10.3390/ma18091931 - 24 Apr 2025

Abstract

This study investigates the corrosion behavior, mass changes, and relative dynamic elastic modulus variations of PC (Portland cement concrete) and G60 (with 60% slag) under two treatment methods: immersion in 3.5% NaCl solution and composite (3.5% NaCl + 5.7% Na₂SO₄ [...] Read more.

This study investigates the corrosion behavior, mass changes, and relative dynamic elastic modulus variations of PC (Portland cement concrete) and G60 (with 60% slag) under two treatment methods: immersion in 3.5% NaCl solution and composite (3.5% NaCl + 5.7% Na₂SO₄) solution, as well as dry–wet cycles. Results indicate that under water and NaCl conditions, no significant mass loss or modulus reduction occurred, with only minor surface efflorescence. However, in the composite solution, severe spalling was observed, with mass loss reaching approximately 1.4% and the relative dynamic modulus decreasing to around 90% after 540 days. Dry–wet cycling accelerated the corrosion process compared to immersion, leading to greater mass loss and modulus reduction. The incorporation of slag improved resistance to ionic penetration in both chemical corrosion and salt crystallization, though this effect diminished with prolonged exposure or increased cycling. Full article

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14 pages, 11366 KiB

Open AccessArticle

A Lithiophilic Artificial Li₃P Interphase with High Li-Ion Conductivity via Solid-State Friction for Lithium Metal Anodes

by Haoling Liu, Wen Pan, Bo Xiao, Yunke Jin, Kun Li, An Wang, Huimiao Li, Zhibin Wu, Yuejiao Chen, Shaozhen Huang, Lin Mei and Libao Chen

Materials 2025, 18(9), 1930; https://doi.org/10.3390/ma18091930 - 24 Apr 2025

Abstract

Interfacial modification strategies for lithium metal anodes have emerged as a promising method to improve cycling stability, suppress lithium dendrite growth, and increase Coulombic efficiency. However, the reported chemical synthesis methods lead to side reactions and side products, which hinder their electrochemical performance. [...] Read more.

Interfacial modification strategies for lithium metal anodes have emerged as a promising method to improve cycling stability, suppress lithium dendrite growth, and increase Coulombic efficiency. However, the reported chemical synthesis methods lead to side reactions and side products, which hinder their electrochemical performance. In this study, we propose a novel and facile red phosphorus-assisted solid-state friction method to in situ fabricate a uniform Li₃P interphase directly on the surface of lithium metal. Interestingly, the as-formed artificial Li₃P interphase with high ionic conductivity and lithium affinity features significantly enhanced interfacial stability and electrochemical kinetics. The symmetric cells based on Li@P with the Li₃P interphase achieved a prolonged lifespan, over 1000 h, at 1 mA/cm² with low polarization. When paired with a high-loading LiFePO₄ cathode (10.5 mg/cm²), the Li@P||LiFePO₄ full cell retained 88.9% of its capacity after stable cycling for 550 cycles at 2 C and further demonstrated the excellent performance and stability of the Li@P‖LiCoO₂ full pouch cell. This study provides an efficient and scalable strategy for stabilizing lithium metal anodes, expanding new ideas for the development of next-generation high-energy-density batteries. Full article

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16 pages, 9435 KiB

Open AccessArticle

Improving Laser Powder Bed Fusion IN718 Process Development Efficiency by Eliminating Pore Defects of Specified Size

by Yuzhong Wang, Wenhua Guo, Wenxian Li, Yaru Zhang, Kaiyue Ma, Qianyu Ji, Rui Han, Yihui Zhang, Chenwei Wang, Sihang Zhao and Bingheng Lu

Materials 2025, 18(9), 1929; https://doi.org/10.3390/ma18091929 - 24 Apr 2025

Abstract

The rapid identification of process windows in laser powder bed fusion (L-PBF) additive manufacturing garnered significant attention for its ability to reduce upfront engineering costs. This study focuses on accelerating the development of process windows by targeting the elimination of specific-size pore defects [...] Read more.

The rapid identification of process windows in laser powder bed fusion (L-PBF) additive manufacturing garnered significant attention for its ability to reduce upfront engineering costs. This study focuses on accelerating the development of process windows by targeting the elimination of specific-size pore defects in L-PBF IN718. A novel relative density–porosity similarity evaluation method (DPSEM) is introduced to evaluate the reliability of porosity data derived from computed tomography (CT). Using the response surface method, the fully dense forming window (e.g., relative density ≥ 99%) was accurately located within a wide process parameter range (18–1000 J/mm³) in a single test. Comparative analysis with the relative density (RD) model highlighted differences in solution set distribution, positioning efficiency, microstructure, and performance within the process window. Results demonstrate that the proposed method effectively eliminates specified size defects (90 μm), achieving a maximum density of 99.5% alongside excellent mechanical properties, including an ultimate tensile strength of 1155 MPa and a yield strength of 908 MPa. In contrast, the RD model achieved a lower maximum density of 98.5%, with mechanical performance compromised by significant MC compound precipitation and keyhole pore accumulation, resulting in an ultimate tensile strength slightly exceeding 910 MPa. Full article

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16 pages, 9483 KiB

Open AccessArticle

Optically Stimulated Luminescence Silicone Foils for 2D Dose Mapping in Proton Radiotherapy

by Michał Sądel, Leszek Grzanka, Jan Swakoń, Damian Wróbel, Sebastian Kusyk, Lily Bossin and Paweł Bilski

Materials 2025, 18(9), 1928; https://doi.org/10.3390/ma18091928 - 24 Apr 2025

Abstract

A novel reusable silicon foil dosimeter based on the new emerging optically stimulated luminescence (OSL) material MgB₄O₇:Ce,Li (MBO) is developed and characterized for dosimetric verification of spatially resolved radiotherapy doses. Direct comparison of the spatial (two-2D towards three-3D) proton [...] Read more.

A novel reusable silicon foil dosimeter based on the new emerging optically stimulated luminescence (OSL) material MgB₄O₇:Ce,Li (MBO) is developed and characterized for dosimetric verification of spatially resolved radiotherapy doses. Direct comparison of the spatial (two-2D towards three-3D) proton dose mapping can be achieved with an appropriately designed optical detection setup equipped with a light source (e.g., LEDs) that illuminates the dosimeter and a highly sensitive CCD camera that simultaneously acquires the 2D OSL light from the foil. The newly designed (2nd generation) optical setup allows the registration of high-resolution 2D proton doses (below 0.1 mm resolution) and reconstruction of the 2D proton dose distribution with an accuracy comparable to that of the Gafchromic^TM foils, the current standard of passive 2D dosimetry in radiotherapy. This article outlines the technology’s potential application with respect to the commercially available Gafchromic^TM EBT3 films in measurements of the clinically relevant, spatial proton dose mapping. The obtained comparison of the proton radial dose profiles (for EBT3 films vs MBO foils) agrees within 5%. The resulting image resolution (0.074 mm/px for MBO foil) corresponded well with the tested EBT3 films (0.085 mm/px), indicating excellent properties for future 3D proton dose verifications of modern radiotherapy techniques (e.g., proton radiotherapy). Full article

(This article belongs to the Section Advanced Materials Characterization)

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20 pages, 4814 KiB

Open AccessArticle

Solvent Evaporation-Induced Self-Assembly of Flexible Cholesteric Liquid Crystal Elastomers: Fabrication, Performance Tuning, and Optimization

by Jinying Zhang, Yexiaotong Zhang, Zhongwei Gao, Jiaxing Yang and Xinye Wang

Materials 2025, 18(9), 1927; https://doi.org/10.3390/ma18091927 - 24 Apr 2025

Abstract

The realization of broad-wavelength tunability of the structural color in Double layered Cholesteric Liquid Crystal Elastomers (DCLCEs), along with good flexibility and processability, presents a significant challenge. This research introduces a facile and effective fabrication technique, Solvent Evaporation-Induced Self-Assembly (SEISA), for the production [...] Read more.

The realization of broad-wavelength tunability of the structural color in Double layered Cholesteric Liquid Crystal Elastomers (DCLCEs), along with good flexibility and processability, presents a significant challenge. This research introduces a facile and effective fabrication technique, Solvent Evaporation-Induced Self-Assembly (SEISA), for the production of DCLCEs exhibiting broad wavelength tunability, superior flexibility, and robust mechanical characteristics. Focusing on initial color tuning, bubble defect minimization, UV photopolymerization, and coating procedures, this research systematically optimizes the fabrication process through experimental investigation of factors like chiral dopant amount, temperature, UV exposure duration, coating thickness, and speed. The method enabled the successful fabrication of DCLCEs with uniform and controllable coloration, demonstrating the effectiveness of this controlled synthesis approach in significantly enhancing structural color features. Upon stretching to 2.8 times its original length, the center wavelength shifted from 613 nm to 404 nm, yielding a tunable bandwidth of up to 209 nm across the visible spectrum. Full article

(This article belongs to the Special Issue Structural and Physical Properties of Liquid Crystals)

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