Materials

9 pages, 2009 KB

Open AccessArticle

Effect of Surface Morphology Formed by Additive Manufacturing on the Adhesion of Dental Cements to Zirconia

by Kumiko Yoshihara, Noriyuki Nagaoka, Sungho Lee, Yukinori Maruo, Fiona Spirrett, Soshu Kirihara, Yasuhiro Yoshida and Bart Van Meerbeek

Materials 2026, 19(3), 563; https://doi.org/10.3390/ma19030563 (registering DOI) - 31 Jan 2026

Abstract

Background: Durable bonding to zirconia remains difficult because its chemically inert surface resists acid etching. Additive manufacturing (AM) enables controlled surface morphology, which may enhance micromechanical retention without additional treatments. Methods: Zirconia specimens with three AM-derived surface designs—(1) concave–convex hemispherical patterns, (2) concave [...] Read more.

Background: Durable bonding to zirconia remains difficult because its chemically inert surface resists acid etching. Additive manufacturing (AM) enables controlled surface morphology, which may enhance micromechanical retention without additional treatments. Methods: Zirconia specimens with three AM-derived surface designs—(1) concave–convex hemispherical patterns, (2) concave hemispherical patterns, and (3) as-printed surfaces—were fabricated using a slurry-based 3D printing system and sintered at 1500 °C. Zirconia specimens fabricated by subtractive manufacturing using CAD/CAM systems, polished with 15 µm diamond lapping film and with or without subsequent alumina sandblasting, served as controls. Surface morphology was analyzed by FE-SEM, and shear bond strength (SBS) was tested after cementation with a resin-based luting agent. Results: SEM revealed regular layered textures and designed hemispherical structures (~300 µm) in AM specimens, along with step-like irregularities (~40 µm) at layer boundaries. The concave–convex AM group showed significantly higher SBS than both sandblasted and polished subtractive-manufactured zirconia (p < 0.05). Vertically printed specimens demonstrated greater bonding strength than those printed parallel to the bonding surface, indicating that build orientation affects resin infiltration and interlocking. Conclusion: AM-derived zirconia surfaces can provide superior and reproducible micromechanical retention compared with conventional treatments. Further optimization of printing parameters and evaluation of long-term durability are needed for clinical application. Full article

(This article belongs to the Special Issue Advanced Dental Materials: From Design to Application, Third Edition)

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18 pages, 7533 KB

Open AccessArticle

Atomic-Scale Insights into Alloying-Induced Interfacial Stability, Adhesion, and Electronic Structure of Mg/Al₃Y Interfaces

by Yunxuan Zhou, Liangjuan Gao, Quanhui Hou, Jun Tan and Zhao Ding

Materials 2026, 19(3), 562; https://doi.org/10.3390/ma19030562 - 30 Jan 2026

Abstract

This work aims to enhance the stability of the Mg/Al₃Y interface through first-principles investigations of low-cost dopants. Density functional theory calculations were employed to systematically examine the bulk properties of Mg and Al₃Y, as well as the structural stability, [...] Read more.

This work aims to enhance the stability of the Mg/Al₃Y interface through first-principles investigations of low-cost dopants. Density functional theory calculations were employed to systematically examine the bulk properties of Mg and Al₃Y, as well as the structural stability, electronic characteristics, and alloying element effects at the Mg(0001)/Al₃Y(0001) interface. The calculated lattice parameters, elastic moduli, and phonon spectra demonstrate that both Mg and Al₃Y are dynamically stable. Owing to the similar hexagonal symmetry and a small lattice mismatch (~1.27%), a low-strain semi-coherent Mg(0001)/(2 × 2)Al₃Y(0001) interface can be constructed. Three representative interfacial stacking configurations (OT, MT, and HCP) were examined, among which the MT configuration exhibits significantly higher work of adhesion, indicating superior interfacial stability. Differential charge density and density of states analyses reveal pronounced charge transfer from Mg to Al/Y atoms and strong orbital hybridization, particularly involving Y-d states, which underpins the enhanced interfacial bonding. Furthermore, the segregation behavior and adhesion enhancement effects of typical alloying elements (Si, Ca, Ti, Mn, Cu, Zn, Zr, and Sn) were systematically evaluated. The results show that Mg-side interfacial sites, especially Mg₂ and Mg₃, are thermodynamically favored for segregation, with Zr and Ti exhibiting the strongest segregation tendency and the most significant improvement in interfacial adhesion. These findings provide fundamental insights into interfacial strengthening mechanisms and offer guidance for the alloy design of high-performance Mg-based composites. Full article

(This article belongs to the Special Issue Multiscale Simulation and Properties of Advanced Materials: Microstructure Evolution and Mechanical Analysis)

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12 pages, 13393 KB

Open AccessArticle

Effect of Gd Alloying on Magnetic Properties of Direct-Quenched Fe-Gd-B Nanocrystalline Alloys

by Linli Wang, Yuanyuan Wang, Zhongao Wang, Ming Nie, Feng Huang, Wangyan Lv, Huameng Fu, Haifeng Zhang and Zhengwang Zhu

Materials 2026, 19(3), 561; https://doi.org/10.3390/ma19030561 - 30 Jan 2026

Abstract

Nanocrystalline Fe-Gd-B alloys were successfully synthesized via Gd alloying in a binary Fe-B system using a single-roller melt-spinning technique. A systematic investigation of Gd content variation (0–4.35 at.%) reveals its critical role in tuning microstructure evolution, thermal stability, and magnetic properties. Crucially, the [...] Read more.

Nanocrystalline Fe-Gd-B alloys were successfully synthesized via Gd alloying in a binary Fe-B system using a single-roller melt-spinning technique. A systematic investigation of Gd content variation (0–4.35 at.%) reveals its critical role in tuning microstructure evolution, thermal stability, and magnetic properties. Crucially, the Fe_90.70Gd_2.32B_6.98 alloy ribbon exhibits optimized magnetic performance, achieving a high saturation magnetic induction (B_s) of 1.67 T and a low coercivity (H_c) of 2.737 kA/m. This enhancement is attributed to the suppression α-Fe grain growth through Gd-induced elevation of the thermal stability of the amorphous matrix, which confines the average crystallite size to 26.3 nm. The refined α-Fe phase contributes to elevated B_s through an increased ferromagnetic fraction, while its nanoscale grain structure, combined with wide magnetic domain configurations, effectively reduces H_c by limiting domain wall pinning sites. These findings establish that the synergistic effect of Gd alloying and Fe/B ratio adjustment is a viable strategy for designing high-performance Fe-based magnetic alloys. Full article

(This article belongs to the Special Issue Physical Metallurgy of Metals and Alloys (4th Edition))

19 pages, 2164 KB

Open AccessArticle

An Experiment and Simulation Study on the Tensile Behavior of Cotton Ring-Spun Yarn with Twisted Staple Fibers

by Xiaoshuang Xiong, Shuyang Wu, Lingyao Zeng, Jiacheng Zhou, Zhaochong Hou, Xiang Li, Mingzhang Chen, Chen Shen and Fei Fan

Materials 2026, 19(3), 560; https://doi.org/10.3390/ma19030560 - 30 Jan 2026

Abstract

This paper investigates the tensile behavior of cotton ring-spun yarn through experimental testing, numerical simulation, and theoretical calculation. Firstly, scanning electron microscope testing of the microscopic geometric morphologies of yarns was performed for the development of basic finite element (FE) models. Then, the [...] Read more.

This paper investigates the tensile behavior of cotton ring-spun yarn through experimental testing, numerical simulation, and theoretical calculation. Firstly, scanning electron microscope testing of the microscopic geometric morphologies of yarns was performed for the development of basic finite element (FE) models. Then, the influences of tensile speed and yarn length on the tensile properties of yarn were studied using tensile experiments. Numerical simulations were further performed to investigate the effects of yarn diameter, twist angle, and friction between fibers on the tensile modulus of yarn. Finally, a modified ‘rule-of-mixtures’ equation was proposed to effectively calculate the tensile modulus of yarn through incorporating the friction correction factor. The experimental results show that the tensile modulus and strength of tested yarn are significantly affected by the yarn structure and are not sensitive to the yarn length and tensile speed. Furthermore, the tensile moduli of yarns obtained from the numerical simulations show a good fitting accuracy with those obtained from experimental tests when the friction coefficient is set to 0.5 in the FE models. The simulation results show that the twist angle and friction coefficient are two key factors affecting the tensile modulus of yarn. The modified ‘rule-of-mixtures’ equation presents better accuracy for the calculation of the tensile modulus of yarn compared with the traditional ‘rule-of-mixtures’ equation, which can be used to replace the FE modeling and simulation and reduce the computational cost. This work will provide a deeper understanding of the mechanical properties of cotton ring-spun yarns and enhance their application in the textile industry. Full article

(This article belongs to the Special Issue Modeling and Numerical Simulations in Materials Mechanics)

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17 pages, 2158 KB

Open AccessArticle

Prediction of the Time-Dependent Elastic Modulus of Fly-Ash Concrete Under Sustained Loads

by Zhuoran Chen, Minghui Liu, Yurong Zhang and Siyi Jia

Materials 2026, 19(3), 559; https://doi.org/10.3390/ma19030559 - 30 Jan 2026

Abstract

In this paper, the time-dependent properties of the elastic modulus of fly ash concrete under sustained compressive load were studied. An experiment was conducted and showed an increment of elastic modulus for two types of fly ash concrete (20% and 40% fly ash [...] Read more.

In this paper, the time-dependent properties of the elastic modulus of fly ash concrete under sustained compressive load were studied. An experiment was conducted and showed an increment of elastic modulus for two types of fly ash concrete (20% and 40% fly ash replacement) under sustained load. The mechanisms of this increment were analyzed, and two Representative Volume Elements (RVEs) were established to represent the micro-heterogeneous space of binder and concrete based on continuum mechanics. The shrinking core models of hydration and pozzolanic reaction were adopted to quantify the volume fraction of each phase within the binder RVE. A prediction model was proposed by incorporating the effects of extra hydration and time-dependent aggregate concentration rate under sustained load. Finally, parameter analysis including the influences of initial loading age and the loading level was conducted. Full article

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

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24 pages, 2220 KB

Open AccessArticle

Synthesis, Properties and Application of Novel 2-Substituted Benzothiazole-Based Oxime Esters

by Monika Dzwonkowska-Zarzycka, Alicja Balcerak-Woźniak and Janina Kabatc-Borcz

Materials 2026, 19(3), 558; https://doi.org/10.3390/ma19030558 - 30 Jan 2026

Abstract

The paper focuses on the synthesis and characterization of the spectroscopic and electrochemical properties of novel oxime esters. Six benzothiazole-based compounds were synthesized using a simple three-step procedure. The chemical structure of novel oxime esters was confirmed by Nuclear Magnetic Resonance spectroscopy ( [...] Read more.

The paper focuses on the synthesis and characterization of the spectroscopic and electrochemical properties of novel oxime esters. Six benzothiazole-based compounds were synthesized using a simple three-step procedure. The chemical structure of novel oxime esters was confirmed by Nuclear Magnetic Resonance spectroscopy (¹H and ¹³C NMR), as well as FT-IR spectroscopy and elemental analysis. The melting point of these compounds was also determined. The spectroscopic properties were studied in 10 solvents with different polarity. The fluorescence quantum yield was determined using Coumarin I as a reference. Additionally, the E_0→0 transition energy was determined. The electrochemical properties were determined using cyclic voltammetry. To justify their use as potential photoinitiators, preliminary studies were conducted to assess their utility in initiating light-induced polymerization. Based on the results, the proposed oxime esters are potential Type I photoinitiators for free radical polymerization. Full article

(This article belongs to the Section Materials Chemistry)

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20 pages, 3685 KB

Open AccessArticle

Profiled Wet Spinning of Polyurethane Composites for Soft Dry Electrodes in Transcutaneous Stimulation Applications

by Alexander V. Shokurov, Ee Qing Tee, Abigail Vogel, Gabriel Gmünder, Kai Röllin, Olivier Lambercy, Dane Donegan, Paulius Viskaitis and Carlo Menon

Materials 2026, 19(3), 557; https://doi.org/10.3390/ma19030557 - 30 Jan 2026

Abstract

Transcutaneous electrical nerve stimulation techniques (TENS) are rapidly gaining attention for their potential in various clinical applications. One such technique is transcutaneous auricular vagus nerve stimulation (taVNS), and it involves delivering nerve stimulation through the skin of the external ear. However, taVNS relies [...] Read more.

Transcutaneous electrical nerve stimulation techniques (TENS) are rapidly gaining attention for their potential in various clinical applications. One such technique is transcutaneous auricular vagus nerve stimulation (taVNS), and it involves delivering nerve stimulation through the skin of the external ear. However, taVNS relies on electrodes that must conform to the complex anatomy of the ear while maintaining stable electrical performance. Conventional taVNS electrodes, typically rigid metal or adhesive pads, are uncomfortable, difficult to position, prone to drying, and costly to produce. Here, we present and evaluate two complementary fabrication approaches for soft dry electrodes suitable for taVNS, which are compliant with curved anatomical features and can be operated without gel. The first employs wet spinning of a conductive elastomer into fibers, while the second extends this method to create hollow cylindrical geometries. The resulting spongy polymer composite electrodes exhibit tunable geometry, high conductivity, mechanical resilience under strain and compression, and low material impedance confirmed through bench and human testing, even under dry conditions. These properties are critical for in-ear and broader transcutaneous stimulation applications, highlighting the potential of these fabrication methods for next-generation soft bioelectronic interfaces. Full article

(This article belongs to the Special Issue New Generation Materials for Advanced Electronic and Biomedical Applications)

10 pages, 652 KB

Open AccessArticle

Magnetotransport and Magneto-Thermoelectric Properties of the Nodel-Line Semimetal SnTaS₂

by Long Ma, Hao Tian, Xiaojian Wu and Dong Chen

Materials 2026, 19(3), 556; https://doi.org/10.3390/ma19030556 - 30 Jan 2026

Abstract

Topological semimetals with nontrivial band structures host a variety of unconventional transport phenomena and have attracted significant attention in condensed matter physics. SnTaS₂, a recently proposed topological nodal-line superconductor with a centrosymmetric layered structure, provides an ideal platform to explore the [...] Read more.

Topological semimetals with nontrivial band structures host a variety of unconventional transport phenomena and have attracted significant attention in condensed matter physics. SnTaS₂, a recently proposed topological nodal-line superconductor with a centrosymmetric layered structure, provides an ideal platform to explore the interplay between topology and electronic transport. Here, we report a comprehensive study of the normal-state magnetotransport and magneto-thermoelectric properties of SnTaS₂ single crystals. We observed large magnetoresistance and nonlinear Hall resistivity at low temperatures, which can be well described by a two-band model, indicating the coexistence of electron and hole carriers. The Seebeck and Nernst coefficients were found to exhibit pronounced and nonmonotonic magnetic field dependences at low temperatures, consistent with multiband transport behavior. Moreover, clear quantum oscillations with a single frequency are detected in both electrical and thermoelectric measurements. Analysis of the oscillations reveals a small effective mass and a nontrivial Berry phase, suggesting that the corresponding Fermi surface arises from a topologically nontrivial band. These findings shed light on the normal-state electronic structure of SnTaS₂ and highlight the important role of topological bands in shaping its transport properties. Full article

(This article belongs to the Section Quantum Materials)

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13 pages, 1821 KB

Open AccessArticle

Particles in Band Saw Coolant: Size Distributions and Implications for Guide Clearances and Friction

by Matthias Schmid, Tobias Tandler, Hans-Christian Möhring and Katharina Schmitz

Materials 2026, 19(3), 555; https://doi.org/10.3390/ma19030555 - 30 Jan 2026

Abstract

In metal band sawing, higher cutting speeds increase frictional heat at sliding guide blocks. Recirculating water-miscible metalworking fluids (MWFs) often lack fine filtration and accumulate debris that can enter the guide–band interface. A 1 L coolant sample collected after 22.5 m² of [...] Read more.

In metal band sawing, higher cutting speeds increase frictional heat at sliding guide blocks. Recirculating water-miscible metalworking fluids (MWFs) often lack fine filtration and accumulate debris that can enter the guide–band interface. A 1 L coolant sample collected after 22.5 m² of cutting contained a particle load of 0.438 g/L; optical sizing yielded a number-median maximum Feret diameter of 345 µm, with particles up to 1.5 mm. Compared with typical guide clearances (~0.1 mm), these sizes imply frequent ingress/bridging and three-body interactions. The coolant viscosity follows an Andrade relation and decreases by ~2% K⁻¹ around 40 °C. HFRR tribometry indicates low steady-state friction (µ ≈ 0.12), comparable to cutting oil. Together, these results provide quantitative design inputs for next-generation guide clearances and targeted filtration/coolant-delivery concepts in high-speed band sawing. Full article

(This article belongs to the Special Issue Cutting Processes for Materials in Manufacturing—Second Edition)

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21 pages, 2852 KB

Open AccessArticle

Carbon-Modified Attapulgite Composite for Rapid Rhodamine B Degradation: High Adsorption Capacity and Photo-Fenton Efficiency

by Naveed Karim, Tin Kyawoo, Saeed Ahmed, Weiliang Tian, Huiyu Li and Yongjun Feng

Materials 2026, 19(3), 554; https://doi.org/10.3390/ma19030554 - 30 Jan 2026

Abstract

A carbon-modified attapulgite composite (C-AATP@CTAB) was synthesized via the hydrothermal method using citric acid as the carbon source and cetyltrimethylammonium bromide (CTAB) as a surface modifier for efficient rhodamine B (Rh-B) removal. Carbon modification elevated the composite’s specific surface area (212 m² [...] Read more.

A carbon-modified attapulgite composite (C-AATP@CTAB) was synthesized via the hydrothermal method using citric acid as the carbon source and cetyltrimethylammonium bromide (CTAB) as a surface modifier for efficient rhodamine B (Rh-B) removal. Carbon modification elevated the composite’s specific surface area (212 m²/g) and negative surface charge (−38.21 mV), significantly enhancing dye adsorption capacity to 666.66 mg/g—nearly double that of unmodified ATP variants (360.4–386.8 mg/g). Kinetic studies confirmed pseudo-second-order adsorption kinetics, attributed to hydrogen bonding and van der Waals interactions between Rh-B and the composite. Under photo-Fenton conditions, C-AATP@CTAB achieved 99.8% Rh-B degradation within 20 min, demonstrating superior catalytic performance in heterogeneous Fenton/photo-Fenton systems. This work establishes a low-cost, high-efficiency adsorbent-catalyst hybrid derived from low-grade attapulgite, offering promising avenues for sustainable wastewater treatment. Full article

(This article belongs to the Topic Functionalized Materials for Environmental Applications)

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27 pages, 12469 KB

Open AccessArticle

In-Plane Mechanical Properties of a Tetra-Missing Rib Symmetry Honeycomb

by Xiaolin Deng, Qi Lu, Zhenzhen Cai and Xinping Zhang

Materials 2026, 19(3), 553; https://doi.org/10.3390/ma19030553 - 30 Jan 2026

Abstract

Tetra-missing rib honeycombs (TMRHs), characterized by monoclinic geometry, exhibit high elastic stiffness but suffer from poor deformation stability and reduced axial load-bearing capacity, which limit their applicability in energy-absorbing and load-sensitive engineering structures. To address these inherent drawbacks, this study proposes two symmetry-enhanced [...] Read more.

Tetra-missing rib honeycombs (TMRHs), characterized by monoclinic geometry, exhibit high elastic stiffness but suffer from poor deformation stability and reduced axial load-bearing capacity, which limit their applicability in energy-absorbing and load-sensitive engineering structures. To address these inherent drawbacks, this study proposes two symmetry-enhanced tetra-missing rib honeycomb configurations through overall axisymmetric design and subunit-level symmetric optimization. A finite element model was established in Abaqus/Explicit and validated against quasi-static compression experiments, demonstrating good agreement in deformation modes and mechanical responses. Systematic numerical investigations were then conducted to compare the mechanical properties and deformation behaviors of three honeycomb layouts, including the conventional TMRH and the proposed symmetric designs. Furthermore, the effects of impact velocity on mechanical performance were examined to evaluate the dynamic response characteristics of the structures. Finally, the influence of subunit angle parameters on the stiffness, energy absorption, and deformation stability of the tetra-missing rib honeycombs was comprehensively analyzed. The results provide insight into the role of symmetry and geometric parameters in improving the mechanical performance of TMRH-based structures and offer guidance for the design of high-performance auxetic honeycombs. Full article

(This article belongs to the Section Mechanics of Materials)

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22 pages, 4589 KB

Open AccessArticle

Evaluation of the Relationship Between Fracture Toughness and Hydrogen-Induced Damage in X70 Line Pipe Steel for Low-Temperature Service

by Reza Khatib Zadeh Davani, Enyinnaya George Ohaeri, Sandeep Yadav, Ehsan Entezari, Jerzy A. Szpunar, Michael J. Gaudet and Muhammad Rashid

Materials 2026, 19(3), 552; https://doi.org/10.3390/ma19030552 - 30 Jan 2026

Abstract

In this study, X70 line pipe steels were subjected to different hot rolling treatments under three conditions with varying roughing (R) and finishing (F) reductions while maintaining the same total reduction to investigate the effect on drop weight tear test (DWTT) toughness and [...] Read more.

In this study, X70 line pipe steels were subjected to different hot rolling treatments under three conditions with varying roughing (R) and finishing (F) reductions while maintaining the same total reduction to investigate the effect on drop weight tear test (DWTT) toughness and hydrogen-induced damage as assessed through electrochemical charging. Scanning Electron Microscope (SEM) images were used to analyze microstructure phases and their volume fractions, while Electron Backscatter Diffraction (EBSD) provided quantitative microscopy, and X-ray analysis examined crystallographic texture. Although all steels exhibited similar microstructure phases, the effective grain size and morphology varied slightly across the thickness. As these variations were minor, the focus shifted to other microstructural features such as textural characteristics. Overall, the steel with the medium R/F reduction demonstrated improved DWTT performance and greater hydrogen cracking and blistering resistance. This was attributed to stronger Transformed Brass (TBr) and Transformed Copper (TC) components, weaker Rotated-Cube (RC) texture, and lower Kernel Average Misorientation (KAM) values. Across the three steels in this work, this study demonstrates that increased fraction of blocky austenite/martensite as secondary phases, high geometrically necessary dislocation (GND) density, and RC texture negatively affect both DWTT and hydrogen damage resistance, whereas gamma (γ)-fiber and {332}<113> textures have positive effects. Improving these metallurgical factors can therefore boost toughness and reduce hydrogen-induced damage in line-pipe steels. Full article

(This article belongs to the Special Issue Corrosion and Mechanical Behavior of Metal Materials (3rd Edition))

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22 pages, 14643 KB

Open AccessArticle

Magnesium Slag-Activated One-Part Geopolymer Concretes: A Viable Supplementary Pathway Toward Low-Carbon Concrete Production

by Tuğba Özdemir Mazlum and Nihat Atmaca

Materials 2026, 19(3), 551; https://doi.org/10.3390/ma19030551 - 30 Jan 2026

Abstract

Amid growing environmental concerns, resource depletion, and the pressing challenges of industrial waste management, this study investigates the potential of magnesium slag (MS) as a sustainable alternative binder in the production of one-part geopolymer concretes (OPGCs). The objective is to reduce reliance on [...] Read more.

Amid growing environmental concerns, resource depletion, and the pressing challenges of industrial waste management, this study investigates the potential of magnesium slag (MS) as a sustainable alternative binder in the production of one-part geopolymer concretes (OPGCs). The objective is to reduce reliance on conventional cementitious materials while promoting the valorization of industrial by-products in construction practices. For this purpose, ten different mixtures were designed by replacing ground granulated blast furnace slag (GGBS), the conventional aluminosilicate precursor, with MS, an innovative aluminosilicate precursor, at replacement levels of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% by weight, using a solid activator. The fresh and hardened properties of these mixtures were systematically evaluated through slump, setting time, density, ultrasonic pulse velocity (UPV), and strength tests, while microstructural characterization was also conducted using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) to further investigate the geopolymerization process, elemental distribution, and the role of MS in binder formation in OPGC. The results revealed that MS incorporation significantly influenced both workability and mechanical performance, and it was confirmed that MS actively participates in geopolymerization and can be effectively utilized up to a certain threshold. Replacement levels up to 30% were found to maintain acceptable mechanical performance, providing evidence that MS is a promising precursor for developing sustainable OPGC. Full article

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

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18 pages, 3925 KB

Open AccessArticle

Evaluating the Degree of Blending and Properties of Recycled Asphalt Mixtures Containing Fine Reclaimed Asphalt Pavement Particles Designed Across Different Methods

by Dong Liu, Hangcheng He, Yanyan Liu, Haidong Dong, Yining Zhang, Xiaoli Zhan, Mingchen Li and Huailei Cheng

Materials 2026, 19(3), 550; https://doi.org/10.3390/ma19030550 - 30 Jan 2026

Abstract

Owing to certain inherent deficiencies in their properties, fine reclaimed asphalt pavement (RAP) particles have not yet been widely reused worldwide, resulting in significant environmental pollution and economic waste. Currently, a diverse array of design methods for asphalt mixes has been proposed. These [...] Read more.

Owing to certain inherent deficiencies in their properties, fine reclaimed asphalt pavement (RAP) particles have not yet been widely reused worldwide, resulting in significant environmental pollution and economic waste. Currently, a diverse array of design methods for asphalt mixes has been proposed. These methods can exert a varying influence on the degree of blending (DoB) and the performance of recycled hot-mix asphalt containing fine RAP particles, and some methods may be better suited for recycling fine RAP particles. However, the specific effects and differences among these various methods have yet to be fully revealed. Therefore, this research comprehensively explored these behaviors. Four distinct mix design formulations were investigated: the dense-graded Asphalt Concrete Group (Group AC), the Stone Mastic Asphalt Group (Group SMA), the High-modulus Asphalt Concrete Group (Group HMAC), and the rejuvenator-modified Asphalt Concrete Group (Group AC+Re). It can be found that the DoB and performance varied across different groups. The DoB spanned from 69% to 82%, with Group SMA showing the highest and Group HMAC exhibiting the lowest. The tensile strength ratio (TSR) of Group AC performed only 73.7%, failing to meet the specification threshold; nevertheless, this shortfall can be compensated by employing alternative methods or adding rejuvenator. Group HMAC exhibited the highest splitting-tensile strength and fracture energy. In addition, the incorporation of rejuvenator can enhance most performance of mixes. Some findings may provide a new perspective for the application of fine RAP particles. Full article

(This article belongs to the Special Issue Novel Materials in Highway Engineering)

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14 pages, 1605 KB

Open AccessArticle

Mechanical Properties of Biochar–Sulfur Composites

by Ewa Syguła, Monika Słupska, Maja Radziemska and Andrzej Białowiec

Materials 2026, 19(3), 549; https://doi.org/10.3390/ma19030549 - 30 Jan 2026

Abstract

The study examines the mechanical strength of sulfur–biochar composites (SBCs), an underexplored area with potential for developing robust materials. Sulfur production, primarily from specialized extraction and waste generation in petroleum refining, yields about 70 million tons annually, necessitating efficient waste management. SBCs were [...] Read more.

The study examines the mechanical strength of sulfur–biochar composites (SBCs), an underexplored area with potential for developing robust materials. Sulfur production, primarily from specialized extraction and waste generation in petroleum refining, yields about 70 million tons annually, necessitating efficient waste management. SBCs were produced using waste-derived biochar and elemental sulfur at varying sulfur contents (60–80%) and employing two fabrication methods: a muffle furnace and an electric burner. The mechanical performance of the composites was evaluated through strength and displacement measurements, with particular emphasis on the influence of processing method and sulfur content. The results demonstrate that both sulfur content and fabrication method significantly affect the mechanical behavior of SBCs. An increase in sulfur content led to a systematic improvement in ultimate strength for all samples. However, composites produced using the electric burner exhibited markedly higher ultimate forces and lower displacements compared to those fabricated in the muffle furnace, indicating superior strength and reduced brittleness. The enhanced performance is attributed to improved sulfur distribution and more effective infiltration of liquid sulfur into the porous biochar structure. These findings confirm the synergistic effect of combining sulfur with biochar and highlight the critical role of processing conditions in developing mechanically robust sulfur–biochar composites suitable for sustainable material applications. Full article

(This article belongs to the Special Issue Advances in Waste Materials’ Valorization)

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15 pages, 3743 KB

Open AccessArticle

Mechanical and Microstructural Characterization of Trapezoidal Corrugated-Core Al Sandwich Panels Under Quasi-Static Compression

by Alessandra Ceci, Girolamo Costanza and Maria Elisa Tata

Materials 2026, 19(3), 548; https://doi.org/10.3390/ma19030548 - 30 Jan 2026

Abstract

Sandwich panels with trapezoidal (corrugated) cores combine low weight, high specific stiffness, and energy absorption capability. This study analyzes four configurations with different core heights by means of microstructural analyses (optical microscopy, SEM/EDS, XRD) and quasi-static compression tests. The tests yield stress–strain curves [...] Read more.

Sandwich panels with trapezoidal (corrugated) cores combine low weight, high specific stiffness, and energy absorption capability. This study analyzes four configurations with different core heights by means of microstructural analyses (optical microscopy, SEM/EDS, XRD) and quasi-static compression tests. The tests yield stress–strain curves with an initial linear stage, a peak, a plateau, and a densification stage. Peak stresses range from 0.5 MPa for the thickest core (P1) to 6.2 MPa for the thinnest core (P4), while the energy absorbed density (EAD) increases with strain: at ε = 30% it varies from 0.031 to 0.670 J/cm³, and at ε = 50% the thin-core configuration reaches ≈1.113 J/cm³. The face sheets and the core are both manufactured from AA 3000 series (Al–Mn) aluminum alloy; widespread micro-porosity and Fe/Mn-rich phases are observed by SEM/EDS. XRD confirms aluminum with different peak intensities ascribable to the manufacturing texture. Increasing the core height promotes earlier local/global instabilities and reduces the peak stress; the thinnest core displays higher stiffness and peak loads. These findings support the use of trapezoidal corrugation where low weight and progressive strain are required. Full article

(This article belongs to the Special Issue Advances in Design and Characterization of Graded and Hierarchical Honeycomb Materials (2nd Edition))

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26 pages, 2672 KB

Open AccessArticle

Polylactide Composites with Mineral Fertilisers—Properties and Biodegradation

by Grzegorz Świderski, Marek Jałbrzykowski, Monika Kalinowska, Małgorzata Pawłowska, Grzegorz Markiewicz, Emilia Bujnowska, Agnieszka Z. Wilczewska and Jolanta Magnuszewska

Materials 2026, 19(3), 547; https://doi.org/10.3390/ma19030547 - 29 Jan 2026

Abstract

Polylactide (PLA) composites were prepared and doped with starch (10% by weight), and mineral salts used as mineral fertilisers (MgSO₄, KNO₃, Ca(NO₃)₂ and Ca₃(PO₄)₂) were prepared. The content of the [...] Read more.

Polylactide (PLA) composites were prepared and doped with starch (10% by weight), and mineral salts used as mineral fertilisers (MgSO₄, KNO₃, Ca(NO₃)₂ and Ca₃(PO₄)₂) were prepared. The content of the added fertilisers was 2% by mass in the composites. The tensile strength properties of the obtained composites were tested. The effect of the addition of fertilisers on the structure of polylactide was analysed using spectroscopic methods (FTIR and FTRaman). The thermal properties of the obtained composites were tested using thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC). PLA composites with fertilisers were tested for biodegradability in two types of soil—field soil and horticultural soil—and in compost. Biodegradability was assessed based on the mass loss of biodegraded composites, spectroscopic tests and visual assessment of changes occurring in the composites. Tests were performed on the respiratory activity of microorganisms in the compost extract in which the tested composites were placed. The addition of mineral salts used in the tested composites significantly influenced the biodegradation rate of the composites. Mineral compounds (MgSO₄, KNO₃ and Ca(NO₃)₂) added to the PLA–starch composite improve its mechanical properties. It should also be noted that the addition of mineral salts to the prepared composites did not affect the chemical structure of polylactide. The addition of mineral salts to PLA also did not significantly affect its thermal properties, as demonstrated by DSC and TG thermal analysis. Full article

(This article belongs to the Special Issue Polymer Composites: Microstructural, Thermal and Mechanical Properties (Fourth Edition))

20 pages, 5710 KB

Open AccessArticle

Steel Slag-Enhanced Cement-Stabilized Recycled Aggregate Bases: Mechanical Performance and PINN-Based Sulfate Diffusion Prediction

by Guodong Zeng, Hao Li, Yuyuan Deng, Xuancang Wang, Yang Fang and Haoxiang Liu

Materials 2026, 19(3), 546; https://doi.org/10.3390/ma19030546 - 29 Jan 2026

Abstract

The application of cement-stabilized recycled aggregate (CSR) in pavement bases is constrained by the high porosity and low strength of recycled aggregate (RA), whereas sulfate transport and durability mechanisms are less reported. To address this issue, this study incorporated high-strength and potentially reactive [...] Read more.

The application of cement-stabilized recycled aggregate (CSR) in pavement bases is constrained by the high porosity and low strength of recycled aggregate (RA), whereas sulfate transport and durability mechanisms are less reported. To address this issue, this study incorporated high-strength and potentially reactive steel slag aggregate (SSA) into CSR to develop steel slag-enhanced cement-stabilized recycled aggregate (CSRS). The mechanical performance of the mixtures was evaluated through unconfined compressive strength (UCS) and indirect tensile strength (ITS) tests, and their durability was assessed using thermal shrinkage and sulfate resistance tests. In addition, a sulfate prediction model based on a physics-informed neural network (PINN) was developed. The results showed that, compared with CSR, the 7-day and 28-day UCS of CSRS increased by 6.7% and 16.0%, respectively, and the ITS increased by 4.3% and 5.9%. Thermal shrinkage tests indicated that CSR and CSRS, incorporating RA and SSA, exhibited slightly higher thermal shrinkage strain than cement-stabilized natural aggregate (CSN). During sulfate attack, SSA significantly improved the sulfate resistance of CSR, with the sulfate resistance coefficient of CSRS increasing by 18.8% compared to CSR. Furthermore, the PINN model predicted that, in 3%, 5%, and 7% sodium sulfate solutions, the sulfate concentration at a 1 mm depth in CSRS was reduced by 35.6%, 21.8%, and 29.4%, respectively, compared to CSR, with an average relative error below 14%, confirming its reliability. Therefore, these findings demonstrate that the incorporation of SSA markedly enhances the mechanical properties and sulfate resistance of CSR, and that the PINN model provides an effective tool for accurate simulation and prediction of sulfate diffusion. Full article

(This article belongs to the Special Issue Sustainable and Eco-Friendly Concrete: Innovations in Green Binders and Recycled Materials)

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16 pages, 89431 KB

Open AccessArticle

Research on the Preparation of 7N-Grade Ultra-High-Purity Arsenic via Transition-State-Controlled Processes

by Lin Zou, Zhaogang Li, Dachun Liu, Guozheng Zha and Wenlong Jiang

Materials 2026, 19(3), 545; https://doi.org/10.3390/ma19030545 - 29 Jan 2026

Abstract

To meet the demand for ultra-high-purity arsenic (≥7N) from crude arsenic (As ≥ 99.3%, Sb ≤ 0.6%), an integrated process combining chlorination, distillation and hydrogen reduction was developed. After preliminary purification of crude arsenic by vacuum distillation, chlorine was applied to convert arsenic [...] Read more.

To meet the demand for ultra-high-purity arsenic (≥7N) from crude arsenic (As ≥ 99.3%, Sb ≤ 0.6%), an integrated process combining chlorination, distillation and hydrogen reduction was developed. After preliminary purification of crude arsenic by vacuum distillation, chlorine was applied to convert arsenic and its impurities into chlorides. Low-boiling chlorides such as SbCl₃, S₂Cl₂ and Se₂Cl₂ were separated by distillation, and ultra-pure AsCl₃ was finally reduced by hydrogen to obtain ultra-high-purity arsenic. Under optimal conditions—10 mL·min⁻¹ Cl₂ flow, 20 mm–30 mm arsenic particle size and 80 mm–90 mm packing height—the chlorine utilization reached 92.3%. Distillation at 433 K with 4 h total reflux and a 5:1 volumetric reflux ratio yielded AsCl₃ of 99.99999% purity, with S and Se below 0.02 ppm and 0.01 ppm, respectively. Hydrogen reduction at 1123 K, H₂/AsCl₃ molar ratio 1.8 and 623 K condensation temperature achieved an arsenic recovery of 99.13%, a chlorine residue of 20 ppb and a final arsenic purity of 99.9999%. This study provides a feasible route for large-scale production of high-purity arsenic. Full article

(This article belongs to the Section Metals and Alloys)

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