Materials

15 pages, 3230 KB

Open AccessArticle

The Influence of PBF-LB/M Part Forming Angle and Support Structure Parameters on the Distortion of Oral Stent

by Yang Liu, Deqiao Xie, Yihan Liu, Zongjun Tian, Shimao Shangguan, Jinbiao Liao and Zhizhong Hua

Materials 2025, 18(19), 4588; https://doi.org/10.3390/ma18194588 - 2 Oct 2025

Abstract

Powder Bed Fusion-Laser Beam/Metals (PBF-LB/M) enables the layer-by-layer fabrication of complex parts; however, non-uniform thermal transients during the process induce high stresses. Geometric constraints dominate stress–relaxation behavior, which is the primary mechanism leading to part distortion. Therefore, the printing structure serves as a [...] Read more.

Powder Bed Fusion-Laser Beam/Metals (PBF-LB/M) enables the layer-by-layer fabrication of complex parts; however, non-uniform thermal transients during the process induce high stresses. Geometric constraints dominate stress–relaxation behavior, which is the primary mechanism leading to part distortion. Therefore, the printing structure serves as a major factor influencing the distortion of PBF-LB/M-fabricated components, of which the forming angle and support structure parameters are the two key factors affecting the printing structure. This study investigates the effects of forming angles and support parameters on the distortion behavior of oral stents manufactured via PBF-LB/M. The results indicate that the magnitude of distortion varies significantly with the forming angle, with the minimum distortion of 0.667 mm occurring at 75°, while the maximum distortion reaches 1.706 mm at 30°. Combined stiffness theory and thermal stress analysis reveal that the thermal stress peaks at a forming angle of 30°, which is governed mainly by the printed cross-sectional area per layer and the cumulative build height. Meanwhile, structural stiffness gradually decreases as the forming angle increases. The study also confirms that support parameters significantly affect distortion, confirming that larger support mesh size and spacing directly contribute to increased maximum distortion. Based on stiffness theory and thermal stress analysis, it is concluded that support structures reduce distortion primarily through two mechanisms: enhancing the overall structural stiffness and facilitating force transmission. Full article

(This article belongs to the Special Issue Manufacturing Technology: Materials, Innovations and Applications, Second Edition)

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19 pages, 1392 KB

Open AccessArticle

Anticorrosion Activity of Low-Zinc Powder Coating Primers Containing Single-Walled Carbon Nanotubes

by Barbara Pilch-Pitera, Łukasz Florczak, Dominika Czachor-Jadacka, Francesco Bellucco, Elwira Węgrzyniak-Kściuczyk, Katarzyna Daszykowska and Małgorzata Żychowicz

Materials 2025, 18(19), 4587; https://doi.org/10.3390/ma18194587 - 2 Oct 2025

Abstract

In this work, low-zinc epoxy powder coating primers with anticorrosive properties were developed. For this purpose, single-walled carbon nanotubes (SWCNTs) were introduced into powder coatings. The obtained coatings were evaluated by performing the following tests: adhesion to steel, roughness, gloss, color, water contact [...] Read more.

In this work, low-zinc epoxy powder coating primers with anticorrosive properties were developed. For this purpose, single-walled carbon nanotubes (SWCNTs) were introduced into powder coatings. The obtained coatings were evaluated by performing the following tests: adhesion to steel, roughness, gloss, color, water contact angle, salt spray, electrochemical impendance spectroscopy (EIS), and transmission scanning microscopy (TEM). The anticorrosion resistance of the powder coating primers obtained depends on the zinc and SWCNT content, as well as the degree of dispersion in the paint. The mechanism of anticorrosion activity was proposed. Full article

(This article belongs to the Special Issue Recent Advances and Emerging Challenges in Functional Coatings (2nd Edition))

11 pages, 2975 KB

Open AccessArticle

Analysis of the Mechanical Properties of the AlSi7CrMnCu2.5 Alloy and Their Changes After Heat Treatment

by Pavel Kraus, Nataša Náprstková, Jaromír Cais, Sylvia Kuśmierczak, Klára Caisová, Anna Rudawska and Jan Sviantek

Materials 2025, 18(19), 4586; https://doi.org/10.3390/ma18194586 - 2 Oct 2025

Abstract

The article deals with the analysis of the mechanical properties of the newly designed aluminum alloy Al-Si7CrMnCu2.5. The research was carried out in order to map a new alloy with a certain addition of chromium and manganese from the point of view of [...] Read more.

The article deals with the analysis of the mechanical properties of the newly designed aluminum alloy Al-Si7CrMnCu2.5. The research was carried out in order to map a new alloy with a certain addition of chromium and manganese from the point of view of mechanical properties and their changes after heat treatment (hardening, artificial aging) with defined parameters. Specifically, properties such as strength limit, yield strength, ductility, hardness, and microhardness were analyzed, both in the cast state and after heat treatment. The alloy was designed as an alternative to the standard Al-Si alloys already used in practice (AlSi7Mg, AlSi7Mg0.3, AlSi8Cu2Mn, AlSi8Cu3), which are mainly used in the production of engine parts and other components for the automotive and aviation industries. As can be seen from the presented results, the experimental AlSi7CrMnCu2.5 alloy exceeds the properties of the other selected alloys by tens of percent already in the cast state in many parameters. After heat treatment, the results achieved are comparable to the mentioned alloys, and in most cases, their values exceed them, especially in terms of ductility and hardness. Full article

(This article belongs to the Special Issue Characterization, Properties, and Applications of New Metallic Alloys)

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14 pages, 9892 KB

Open AccessArticle

Research on Chromium-Free Passivation and Corrosion Performance of Pure Copper

by Xinghan Yu, Ziye Xue, Haibo Chen, Wei Li, Hang Li, Jing Hu, Jianli Zhang, Qiang Chen, Guangya Hou and Yiping Tang

Materials 2025, 18(19), 4585; https://doi.org/10.3390/ma18194585 - 2 Oct 2025

Abstract

In response to the actual needs of pure copper bonding wires, it is crucial to develop a chromium-free passivator that is environmentally friendly and has excellent corrosion resistance. In this study, three different composite organic formulations of chromium-free passivation solutions are selected: 2-Amino-5-mercapto-1,3,4 [...] Read more.

In response to the actual needs of pure copper bonding wires, it is crucial to develop a chromium-free passivator that is environmentally friendly and has excellent corrosion resistance. In this study, three different composite organic formulations of chromium-free passivation solutions are selected: 2-Amino-5-mercapto-1,3,4 thiadiazole (AMT) + 1-phenyl-5-mercapto tetrazolium (PMTA), 2-mercaptobenzimidazole (MBI) + PMTA, and Hexadecanethiol (CHS) + sodium dodecyl sulfate (SDS). The performance analysis and corrosion mechanism were compared with traditional hexavalent chromium passivation through characterization techniques such as XRD, SEM, and XPS. The results show that the best corrosion resistance formula is the combination of the PMTA and MBI passivation agent, and all its performances are superior to those of hexavalent chromium. The samples treated with this passivation agent corrode within 18 s in the nitric acid drop test, which is better than the 16 s for Cr⁶⁺ passivation. The samples do not change color after being immersed in salt water for 48 h. Electrochemical tests and high-temperature oxidation test also indicate better corrosion resistance than Cr⁶⁺ passivation. Through the analysis of functional groups and bonding, the excellent passivation effect is demonstrated to be achieved by the synergistic action of the chemical adsorption film formation of PMTA and the anchoring effect of MBI. Eventually, a dense Cu-PMTA-BMI film is formed on the surface, which effectively blocks the erosion of the corrosive medium and significantly improves the corrosion resistance. Full article

(This article belongs to the Special Issue Antibacterial and Corrosion-Resistant Coatings for Marine Application)

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19 pages, 4582 KB

Open AccessArticle

Sustainable Bio-Gelatin Fiber-Reinforced Composites with Ionic Coordination: Mechanical and Thermal Properties

by Binrong Zhu, Qiancheng Wang, Yang Wei, Jinlong Pan and Huzi Ye

Materials 2025, 18(19), 4584; https://doi.org/10.3390/ma18194584 - 2 Oct 2025

Abstract

A novel bio-gelatin fiber-reinforced composite (BFRC) was first developed by incorporating industrial bone glue/gelatin as the matrix, magnesium oxide (MgO) as an additive, and natural or synthetic fibers as reinforcement. Systematic tests evaluated mechanical, impact, and thermal performance, alongside microstructural mechanisms. Results showed [...] Read more.

A novel bio-gelatin fiber-reinforced composite (BFRC) was first developed by incorporating industrial bone glue/gelatin as the matrix, magnesium oxide (MgO) as an additive, and natural or synthetic fibers as reinforcement. Systematic tests evaluated mechanical, impact, and thermal performance, alongside microstructural mechanisms. Results showed that polyethylene (PE) fiber-reinforced composites achieved a tensile strength of 3.40 MPa and tensile strain of 10.77%, with notable improvements in compressive and flexural strength. PE-based composites also showed excellent impact energy absorption, while bamboo fiber-reinforced composites exhibited higher thermal conductivity. Microstructural analysis revealed that coordination between Mg²⁺ ions and amino acids in gelatin formed a stable cross-linked network, densifying the matrix and improving structural integrity. A multi-criteria evaluation using the TOPSIS model identified the BC-PE formulation as the most balanced system, combining strength, toughness, and thermal regulation. These findings demonstrate that ionic coordination and fiber reinforcement can overcome inherent weaknesses of gelatin matrices, offering a sustainable pathway for building insulation and cushioning packaging applications. Full article

(This article belongs to the Section Advanced Composites)

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16 pages, 5686 KB

Open AccessArticle

Study on Erosion Wear Resistance of 18Ni300 Maraging Steel Remanufactured by Underwater Laser Direct Metal Deposition

by Zhandong Wang, Linzhong Wu, Shibin Wang and Chunke Wang

Materials 2025, 18(19), 4583; https://doi.org/10.3390/ma18194583 - 2 Oct 2025

Abstract

Erosion wear is a major cause of surface degradation in metallic materials exposed to harsh marine environments. In this study, the erosion wear resistance of the 18Ni300 maraging steel repaired by underwater direct metal deposition (UDMD) is investigated. Results show that UDMD is [...] Read more.

Erosion wear is a major cause of surface degradation in metallic materials exposed to harsh marine environments. In this study, the erosion wear resistance of the 18Ni300 maraging steel repaired by underwater direct metal deposition (UDMD) is investigated. Results show that UDMD is successfully applied to repair the 18Ni300 samples in underwater environment. Full groove filling and sound metallurgical bonding without cracks are achieved, demonstrating its potential for underwater structural repair. Microstructural analyses reveal good forming quality with fine cellular structures and dense lath martensite in the deposited layer, attributed to rapid solidification under water cooling. Compared to in-air DMD, the UDMD sample exhibits higher surface microhardness due to increased dislocation density and microstructural refinement. Erosion wear behavior is evaluated at 30° and 90° impingement angles, showing that wear mechanisms shift from micro-cutting and plowing at 30° to indentation, crack propagation, and spallation at 90°. The UDMD samples demonstrate superior erosion wear resistance with lower mass loss, particularly at 30°, benefiting from surface work hardening and microstructural advantages. Progressive surface hardening occurs during erosion due to severe plastic deformation, reducing wear rates over time. The combination of refined microstructure, high dislocation density, and enhanced work hardening capability makes UDMD-repaired steel highly resistant to erosive degradation. These findings confirm that UDMD is a promising technique for repairing marine steel structures, offering enhanced durability and long-term performance in harsh offshore environments. Full article

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15 pages, 4826 KB

Open AccessArticle

Effect of Silane Surface Treatments on the Interfacial Shear Strength Between Cotton Yarn and Poly(Lactic Acid) Resin

by Gyu Hyeon Kim, Young Soo Cho, Gye Hwa Shin and Jun Tae Kim

Materials 2025, 18(19), 4582; https://doi.org/10.3390/ma18194582 - 2 Oct 2025

Abstract

This study explores the enhancement of mechanical properties in cotton yarn-reinforced poly(lactic acid) (PLA) biocomposites, aimed at providing a sustainable alternative to petroleum-based plastics. The primary challenge addressed is the low interfacial shear strength (ISFF) between the hydrophilic cotton yarn and the hydrophobic [...] Read more.

This study explores the enhancement of mechanical properties in cotton yarn-reinforced poly(lactic acid) (PLA) biocomposites, aimed at providing a sustainable alternative to petroleum-based plastics. The primary challenge addressed is the low interfacial shear strength (ISFF) between the hydrophilic cotton yarn and the hydrophobic PLA matrix. To overcome this, cotton yarn surface was chemically modified using silane treatment. Cotton yarns were aligned on a metal frame and treated with hydrolyzed silane solutions at concentrations of 1%, 2%, 3%, and 4% (w/v) for 3 h. Although the tensile stress of the cotton yarn decreased significantly (p < 0.05) with higher silane concentrations, from 520.46 MPa (untreated) to 340.88 MPa (4% silane-treated), the IFSS improved significantly (p < 0.05) from 5.63 MPa to 12.12 MPa. Consequently, the tensile stress of the cotton yarn/PLA biocomposites increased significantly (p < 0.05), from 20.74 MPa (untreated) to 41.58 MPa (4% silane-treated). This is because the increased IFSS achieved through silane treatment allowed the PLA polymer to more firmly connect adjacent cotton fibers, resulting in maximum strength. FTIR and SEM analyses confirmed successful surface modification of the cotton yarn. These findings demonstrate that silane treatment effectively enhances interfacial bonding between cotton yarn and PLA resin, leading to improved mechanical performance of the biocomposites. Full article

(This article belongs to the Special Issue Bio-Based Natural Fiber Composite Materials)

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18 pages, 5613 KB

Open AccessArticle

The Impact of Selected ESD Parameters on the Properties of Tungsten Layers

by Piotr Młynarczyk, Damian Bańkowski and Wojciech Depczyński

Materials 2025, 18(19), 4581; https://doi.org/10.3390/ma18194581 - 2 Oct 2025

Abstract

This article presents studies of surface layers produced by electro-spark deposition (ESD) on cast iron using a W-Ni-Co sintered electrode. To minimize the number of required experiments, a two-factor, five-level Hartley experimental design was chosen. The assessment involved observing the effect of voltage [...] Read more.

This article presents studies of surface layers produced by electro-spark deposition (ESD) on cast iron using a W-Ni-Co sintered electrode. To minimize the number of required experiments, a two-factor, five-level Hartley experimental design was chosen. The assessment involved observing the effect of voltage and capacitor capacity during the ESD process (on layer thickness and wear of the sample and counter-sample under technically dry friction conditions). Microscopic and tomographic observations were performed to analyze the thickness and structure of the layers. Image analysis methods were employed to examine the cross-section of the layers. ESD diffusion analyses were performed on the produced layer. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were performed to characterize the microstructure and composition of the coating. In addition, in order to evaluate the performance properties of tungsten coatings, the tribological tests were also conducted on a TRB³ Ball-on-Disc testing device. Hardness tests confirm an increase in the hardness of cast iron with a tungsten layer by over 400 µHV. The tests showed that higher voltages during the ESD process result in thicker layers and reduced wear of the sample with a tungsten layer at the expense of increased wear of the counter-sample (ball). Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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52 pages, 9282 KB

Open AccessReview

Carrier Mobility, Electrical Conductivity, and Photovoltaic Properties of Ordered Nanostructures Assembled from Semiconducting Polymers

by Maria Pop and Ioan Botiz

Materials 2025, 18(19), 4580; https://doi.org/10.3390/ma18194580 - 2 Oct 2025

Abstract

Nanostructures composed of semiconducting polymers that adopt highly ordered molecular arrangements at the nano- and microscale typically exhibit enhanced optoelectronic properties. In this study, we aim to establish a comprehensive correlation between nanostructures with varying degrees of molecular order—fabricated using diverse processing methods—and [...] Read more.

Nanostructures composed of semiconducting polymers that adopt highly ordered molecular arrangements at the nano- and microscale typically exhibit enhanced optoelectronic properties. In this study, we aim to establish a comprehensive correlation between nanostructures with varying degrees of molecular order—fabricated using diverse processing methods—and their tailored optoelectronic properties, as demonstrated by various energy devices. These properties include carrier mobility, electrical conductivity, and photovoltaic capabilities measured predominantly in films tens to hundreds of nanometers thick based on semiconducting polymers. Full article

(This article belongs to the Special Issue Advances in Opto-Electronic Functional Materials and Devices)

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10 pages, 4647 KB

Open AccessArticle

Color-Tunable and Efficient CsPbBr₃ Photovoltaics Enabled by a Triple-Functional P3HT Modification

by Yanan Zhang, Zhizhe Wang, Dazheng Chen, Tongwanming Zheng, Menglin Yan, Yibing He, Zihao Wang, Weihang Zhang and Chunfu Zhang

Materials 2025, 18(19), 4579; https://doi.org/10.3390/ma18194579 - 2 Oct 2025

Abstract

All inorganic CsPbBr₃ possesses ideal stability in halide perovskites, but its wide bandgap and relatively poor film quality seriously limit the performance enhancement and possible applications of perovskite solar cells (PSCs). In this work, a triple-functional poly(3-Hexylthiophene) (P3HT) modifier was introduced to [...] Read more.

All inorganic CsPbBr₃ possesses ideal stability in halide perovskites, but its wide bandgap and relatively poor film quality seriously limit the performance enhancement and possible applications of perovskite solar cells (PSCs). In this work, a triple-functional poly(3-Hexylthiophene) (P3HT) modifier was introduced to realize color-tunable semi-transparent CsPbBr₃ PSCs. From the optical perspective, the P3HT acted as the assistant photoactive layer, enhanced the light absorption capacity of the CsPbBr₃ film, and broadened the spectrum response range of devices. In view of the hole transport layer, P3HT modified the energy level matching between the CsPbBr₃/anode interface and facilitated the hole transport. Simultaneously, the S⁻ in P3HT formed a more stable Pb-S bond with the uncoordinated Pb²⁺ on the surface of CsPbBr₃ and played the role of a defect passivator. As the P3HT concentration increased from 0 to 15 mg/mL, the color of CsPbBr₃ devices gradually changed from light yellow to reddish brown. The PSC treated by an optimal P3HT concentration of 10 mg/mL achieved a champion power conversion efficiency (PCE) of 8.71%, with a V_OC of 1.30 V and a J_SC of 8.54 mA/cm², which are remarkably higher than those of control devices (6.86%, 1.22 V, and 8.21 mA/cm²), as well its non-degrading stability and repeatability. Here, the constructed CsPbBr₃/P3HT heterostructure revealed effective paths for enhancing the photovoltaic performance of CsPbBr₃ PSCs and boosted their semi-transparent applications in building integrated photovoltaics (BIPVs). Full article

(This article belongs to the Special Issue Advances in Perovskite Solar Cells: Recent Advances and Future Prospects)

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23 pages, 12417 KB

Open AccessArticle

Optimizing EDM of Gunmetal with Al₂O₃-Enhanced Dielectric: Experimental Insights and Machine Learning Models

by Saumya Kanwal, Usha Sharma, Saurabh Chauhan, Anuj Kumar Sharma, Jitendra Kumar Katiyar, Rabesh Kumar Singh and Shalini Mohanty

Materials 2025, 18(19), 4578; https://doi.org/10.3390/ma18194578 - 2 Oct 2025

Abstract

This study investigates the optimization of electric discharge machining (EDM) parameters for gunmetal using copper electrodes in two different dielectric environments, which are conventional EDM oil and EDM oil infused with Al₂O₃ nanoparticles. A Taguchi L27 orthogonal array design was [...] Read more.

This study investigates the optimization of electric discharge machining (EDM) parameters for gunmetal using copper electrodes in two different dielectric environments, which are conventional EDM oil and EDM oil infused with Al₂O₃ nanoparticles. A Taguchi L27 orthogonal array design was used to evaluate the effects of current, voltage, and pulse-on time on Material Removal Rate (MRR), Electrode Wear Rate (EWR), and surface roughness (Ra, Rq, and Rz). Analysis of Variance (ANOVA) was used to statistically evaluate the influence of each parameter on machining performance. In addition, machine learning models including Linear Regression, Ridge Regression, Support Vector Regression, Random Forest, Gradient Boosting, and Neural Networks were implemented to predict performance outcomes. The originality of this research is not only rooted in the introduction of new models; rather, it is also found in the comparative analysis of various machine learning methodologies applied to the performance of electrical discharge machining (EDM) utilizing Al₂O₃-enhanced dielectrics. This investigation focuses specifically on gunmetal, a material that has not been extensively studied within this framework. The nanoparticle-enhanced dielectric demonstrated improved machining performance, achieving approximately 15% higher MRR, 20% lower EWR, and 10% improved surface finish compared to conventional EDM oil. Neural Networks consistently outperformed other models in predictive accuracy. Results indicate that the use of nanoparticle-infused dielectrics in EDM, coupled with data-driven optimization techniques, enhances productivity, tool life, and surface quality. Full article

(This article belongs to the Special Issue Non-conventional Machining: Materials and Processes)

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46 pages, 7904 KB

Open AccessArticle

Volume Changes of Alkali-Activated Slag-Based Mortars and Concretes in Sealed and Free Conditions

by Maïté Lacante, Brice Delsaute and Stéphanie Staquet

Materials 2025, 18(19), 4577; https://doi.org/10.3390/ma18194577 - 2 Oct 2025

Abstract

The goal of this paper is to assess the evolution of the autogenous strains as well as the thermal strains (thanks to the assessment of the coefficient of thermal expansion) of alkali-activated slag-based materials at early age. The effect of the sand and [...] Read more.

The goal of this paper is to assess the evolution of the autogenous strains as well as the thermal strains (thanks to the assessment of the coefficient of thermal expansion) of alkali-activated slag-based materials at early age. The effect of the sand and the coarse aggregates on the paste and mortar scale to upscale to mortar and concrete, respectively, has been investigated as a function of the age of the material. The restraint imposed by the sand on the paste seemed more significant than that of the coarse aggregate on the mortar. In addition, the long-term autogenous strains have been monitored on the mortar scale. These results revealed a separation into groups based on the solution concentration. Different testing methods were also compared. Thermal and autogenous strains were monitored with a customized testing device where the thermal variations are controlled. These devices were the horizontal corrugated tubes method (for tests on paste and mortar scales) and the vertical corrugated tubes method (for tests on mortar and concrete scales). Depending on the compositions (lower concentration), good correlations can be obtained between the two testing methods. Moreover, the autogenous strain of two different specimen sizes was also assessed manually (initially for the long-term), but early-age comparison showed good correlation for lower solution-to-binder ratios. On the concrete scale, a correlation based on the modified equations from the standards was established between the compressive strength and the tensile strength, obtained from the splitting tensile test. Full article

(This article belongs to the Special Issue Advances in Microstructure and Sustainability of Geopolymers and Alkali Activated Materials)

23 pages, 948 KB

Open AccessArticle

Impact of Hot Water Extraction on the Chemical Composition of Hemp (Cannabis sativa L.)

by Kamil Roman and Monika Marchwicka

Materials 2025, 18(19), 4576; https://doi.org/10.3390/ma18194576 - 2 Oct 2025

Abstract

An investigation of the effect of intense Hot Water Extraction (HWE) on the chemical properties and processability of shredded hemp stalks (Cannabis sativa L.) is presented in this study. The chemical composition of untreated hemp was compared to that of hemp subjected [...] Read more.

An investigation of the effect of intense Hot Water Extraction (HWE) on the chemical properties and processability of shredded hemp stalks (Cannabis sativa L.) is presented in this study. The chemical composition of untreated hemp was compared to that of hemp subjected to V and XV successive HWE cycles. This study investigated changes in selected chemical compounds, such as extractives, lignin, cellulose, ash, and monosaccharides such as glucose and xylose. Additionally, post-HWE liquids were analyzed. Lignin content was determined by the UV–VIS spectrophotometry method, whereas monosaccharides (glucose, xylose) and inhibitors (formic acid, acetic acid, levulinic acid, ethanol, 5-(hydroxymethyl)furfural, and furfural) were identified by HPLC. Extractives and ash were effectively removed by the HWE process, decreasing from 3.2 to 2.0% and from 3.9% to 2.7%, respectively. The reduction in acid-soluble lignin was an important finding, indicating a selective modification of the lignin matrix. By the end of V cycles, xylose content in the liquid phase significantly increased from 117.9% to 19.4%, indicating a reduction in hemicelluloses. The cellulose content of the solid material rose from 42.9% to 46.2% at the end of XV cycles. Full article

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42 pages, 14981 KB

Open AccessReview

Metallography of Quasicrystals in Al-Alloys

by Tonica Bončina and Franc Zupanič

Materials 2025, 18(19), 4575; https://doi.org/10.3390/ma18194575 - 1 Oct 2025

Abstract

Quasicrystals are ordered phases without periodicity. They are often found in aluminium and other alloys. They can appear in different sizes. Therefore, several metallographic and characterisation techniques are required to fully determine their shape, size, crystallography, and chemical composition. This review paper gives [...] Read more.

Quasicrystals are ordered phases without periodicity. They are often found in aluminium and other alloys. They can appear in different sizes. Therefore, several metallographic and characterisation techniques are required to fully determine their shape, size, crystallography, and chemical composition. This review paper gives special attention to identifying quasicrystals in aluminium alloys using classical metallographic techniques, such as etching, deep etching, and particle extraction, which allow the investigation of larger areas by light and scanning electron microscope, giving additional information by combining with complementary high-resolution techniques. Full article

(This article belongs to the Section Advanced Materials Characterization)

18 pages, 1257 KB

Open AccessArticle

Low-Velocity Impact Behavior of PLA BCC Lattice Structures: Experimental and Numerical Investigation with a Novel Dimensionless Index

by Giuseppe Iacolino, Giuseppe Mantegna, Emilio V. González, Giuseppe Catalanotti, Calogero Orlando, Davide Tumino and Andrea Alaimo

Materials 2025, 18(19), 4574; https://doi.org/10.3390/ma18194574 - 1 Oct 2025

Abstract

Lattice structures are lightweight architected materials particularly suitable for aerospace and automotive applications due to their ability to combine mechanical strength with reduced mass. Among various topologies, Body-Centered Cubic (BCC) lattices are widely employed for their geometric regularity and favorable strength-to-weight ratio. Advances [...] Read more.

Lattice structures are lightweight architected materials particularly suitable for aerospace and automotive applications due to their ability to combine mechanical strength with reduced mass. Among various topologies, Body-Centered Cubic (BCC) lattices are widely employed for their geometric regularity and favorable strength-to-weight ratio. Advances in Additive Manufacturing (AM) have enabled the precise and customizable fabrication of such complex architectures, reducing material waste and increasing design flexibility. This study investigates the low-velocity impact behavior of two polylactic acid (PLA)-based BCC lattice panels differing in strut diameter: BCC1.5 (1.5 mm) and BCC2 (2 mm). Experimental impact tests and finite element simulations were performed to evaluate their energy absorption () capabilities. In addition to conventional global performance indices, a dimensionless parameter, is introduced to quantify the ratio between local plastic indentation and global displacement, allowing for a refined characterization of deformation modes and structural efficiency. Results show that BCC1.5 absorbs more energy than BCC2, despite the latter’s higher stiffness. This suggests that thinner struts enhance energy dissipation under dynamic loading. Despite minor discrepancies, numerical simulations provide accurate estimations of and support the robustness of the index within the examined configuration, highlighting its potential to deformation heterogeneity. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

20 pages, 4603 KB

Open AccessArticle

Recyclable MnCl₂-Fe₂O₃@CNT as Sulfur and Water-Resistant Sorbent for Gaseous Elemental Mercury Removal from Coal Combustion Flue Gas

by Zhuo Liu, Yuchi Chen, Hao Rong, Cui Jie, Xiyan Peng and Honghu Li

Materials 2025, 18(19), 4573; https://doi.org/10.3390/ma18194573 - 1 Oct 2025

Abstract

Mercury poses serious hazards to human health. Carbon nanotube (CNT) is a potential material for elemental mercury (Hg⁰) adsorption removal, however, it shows susceptibility to SO₂ and H₂O. Herein, CNT is first decorated with Fe₂O₃ [...] Read more.

Mercury poses serious hazards to human health. Carbon nanotube (CNT) is a potential material for elemental mercury (Hg⁰) adsorption removal, however, it shows susceptibility to SO₂ and H₂O. Herein, CNT is first decorated with Fe₂O₃ then modified with MnCl₂ (MnCl₂-Fe₂O₃@CNT) to enhance SO₂ and H₂O resistance. The Hg⁰ removal performance and physical–chemical properties of samples are comprehensively studied. MnCl₂(10)FeCNT (10 wt% MnCl₂ content) has a high specific surface area (775.76 m²·g⁻¹) and abundant active chlorine (35.01% Cl* content) as well as oxygen species (84.23% O_α content), which endows it with excellent Hg⁰ adsorption capacity (25.06 mg·g⁻¹) and good SO₂ and H₂O resistance. Additionally, the superparamagnetic property can enable MnCl₂(10)FeCNT to be conveniently recycled. After fifth regeneration, MnCl₂(10)FeCNT can still achieve >90% Hg⁰ removal. The abundant active chlorine and oxygen species over MnCl₂(10)FeCNT are responsible for Hg⁰ removal with HgCl₂ as the primary product. This work demonstrates the enhancement of CNT’s resistance to SO₂ and H₂O by Fe₂O₃ and MnCl₂ modification, which has potential application in flue gas mercury removal. Full article

(This article belongs to the Section Green Materials)

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19 pages, 9405 KB

Open AccessArticle

Gleeble-Simulated Ultra-Fast Cooling Unlocks Strength–Ductility Synergy in Fully Martensitic Ti-6Al-4V

by Yaohong Xiao, Hongling Zhou, Pengwei Liu and Lei Chen

Materials 2025, 18(19), 4572; https://doi.org/10.3390/ma18194572 - 1 Oct 2025

Abstract

In additively manufactured (AM) Ti-6Al-4V, the role of martensitic α′ in governing brittleness versus toughness remains debated, largely because complex thermal histories and other intertwined physical factors complicate interpretation. To isolate and clarify the intrinsic effect of cooling rate, we employed a Gleeble [...] Read more.

In additively manufactured (AM) Ti-6Al-4V, the role of martensitic α′ in governing brittleness versus toughness remains debated, largely because complex thermal histories and other intertwined physical factors complicate interpretation. To isolate and clarify the intrinsic effect of cooling rate, we employed a Gleeble thermal simulator, which enables precisely controllable cooling rates while simultaneously achieving ultra-fast quenching comparable to AM (up to ~7000 °C/s). By varying the cooling rate only, three distinct microstructures were obtained: α/β, α_m/α′, and fully α′. Compression tests revealed that the ultra-fast-cooled fully martensitic Ti-6Al-4V attained both higher strength and larger fracture strain, with densely distributed elongated dimples indicative of ductile failure. Three-dimensional microstructures reconstructed from microscopy, analyzed using an EVP-FFT crystal plasticity model, demonstrated that refined α′ laths and abundant high-angle boundaries promote more homogeneous strain partitioning and reduce stress triaxiality, thereby delaying fracture. These results provide potential evidence that extreme-rate martensitic transformation can overcome the conventional strength–ductility trade-off in Ti-6Al-4V, offering a new paradigm for processing titanium alloys and AM components with superior performance. Full article

(This article belongs to the Special Issue Alloy Strengthening Mechanisms, Microstructure Control, and Performance Optimization)

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17 pages, 5033 KB

Open AccessArticle

The Influence Mechanism of a Scanning Strategy on the Fatigue Life of SLM 316L Stainless Steel Forming Parts

by Huijun Ma, Xiaoling Yan and Huiwen Fu

Materials 2025, 18(19), 4571; https://doi.org/10.3390/ma18194571 - 1 Oct 2025

Abstract

The quality of SLM formed parts is one of the key factors of the promotion and application of additive manufacturing technology. The scanning strategy fundamentally affects the fatigue life of SLM 316L stainless steel parts by regulating residual stress, defect distribution, and microstructure. [...] Read more.

The quality of SLM formed parts is one of the key factors of the promotion and application of additive manufacturing technology. The scanning strategy fundamentally affects the fatigue life of SLM 316L stainless steel parts by regulating residual stress, defect distribution, and microstructure. Three different scanning strategies (meander scanning, stripe scanning, and chessboard scanning) were adopted to prepare the specimens. High cycle fatigue loading was applied to SLM 316L stainless steel specimens prepared by different scanning strategies. The thermal conductivity characteristics during the SLM part forming process were analyzed based on scanning electron microscopy observations of microstructure of SLM specimens, and the mechanism of residual stress and internal defect generation were revealed. The scanning direction determines the growth direction of the grains, thereby affecting the anisotropy and overall fatigue performance of SLM 316L stainless steel parts. The scanning path determines the overlap and lap joint of the melt pool, directly affecting the number, size, and location of pores and incomplete fusion defects. The scanning strategy affects the distribution and magnitude of residual stresses by changing the path of heat source movement. Theoretical analysis and experimental verification results indicate that the selection of a scanning strategy is an effective method for optimizing the fatigue performance of SLM parts. Full article

(This article belongs to the Section Metals and Alloys)

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16 pages, 1417 KB

Open AccessArticle

Flammability and Thermal Properties of Rigid Polyurethane Foams Modified with Waste Biomass and Ash

by Anna Magiera, Monika Kuźnia, Rafał Stanik, Katarzyna Kaczorek-Chrobak, Maik Gude and Bartłomiej K. Papis

Materials 2025, 18(19), 4570; https://doi.org/10.3390/ma18194570 - 1 Oct 2025

Abstract

The increasing demand for sustainable construction materials has driven interest in utilizing waste biomass within polymer composites. Rigid polyurethane foams, widely valued for thermal insulation, exhibit a significant flammability issue. This study investigates the impact of incorporating various waste biomass materials, including brewers’ [...] Read more.

The increasing demand for sustainable construction materials has driven interest in utilizing waste biomass within polymer composites. Rigid polyurethane foams, widely valued for thermal insulation, exhibit a significant flammability issue. This study investigates the impact of incorporating various waste biomass materials, including brewers’ spent grain, coffee grounds, and soybean husk and their combustion ashes on the selected properties of rigid polyurethane foams. The primary objective is to assess the potential of these eco-friendly additives as replacements for traditional raw materials, aiming to enhance fire resistance and thermal stability and thereby promoting circular economy principles in the construction sector. Composite foam samples were fabricated using a mixing and casting technique, incorporating 5% wt. of fillers into the polymer matrix. Thermal stability and flammability were evaluated using cone calorimetry and thermogravimetric analysis. The findings indicated that while biomass inclusion did not significantly improve char formation, the addition of ash substantially increased char yield, a critical factor in fire suppression. Although biomass and ash may influence flammability, they do not inherently bolster the intrinsic thermal stability of the polyurethane matrix itself. Full article

(This article belongs to the Special Issue Advanced Green Building Materials: Synthesis, Characterization and Sustainable Development Technologies)

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