Materials

24 pages, 65677 KB

Open AccessArticle

Optimizing the Utilization Rate and Performance of 3D-Printed Mortar with Dual-Size Recycled Sand

by Jie Huang, Xinjie Wang, Quanbin Shi, Pu Yuan and Minqi Hua

Materials 2026, 19(7), 1478; https://doi.org/10.3390/ma19071478 - 7 Apr 2026

To enhance the utilization rate and mechanical performance of recycled sand (RS) in extrusion-based 3D printing, this study investigates the influence of varying incorporation ratios of RS across two particle size fractions: 0.075–1.18 mm (RS01) and 1.18–2.36 mm (RS12). The RS utilization rate [...] Read more.

To enhance the utilization rate and mechanical performance of recycled sand (RS) in extrusion-based 3D printing, this study investigates the influence of varying incorporation ratios of RS across two particle size fractions: 0.075–1.18 mm (RS01) and 1.18–2.36 mm (RS12). The RS utilization rate was determined via the material balance method, while microstructural mechanisms were analyzed using scanning electron microscopy and Vickers microhardness testing. The results indicate that: a combination of 75% RS01 and 25% RS12 achieves the maximum RS utilization rate of 84.3%. At an RS12/RS01 ratio of 1:3, the printed specimens exhibit the smallest tilt angles in bidirectional buildability tests, measuring 7.6° and 7.2°, with corresponding tan θ values of 0.066 and 0.063. Compared to mortar with 100% RS01, this optimized mixture yields average increases of 36.5% in compressive strength, 40.7% in flexural strength, and 6.8% in interlayer splitting strength. Analysis of variance indicates that different particle size combinations have a significant effect on the mechanical properties. Microhardness analysis reveals that the combination of 75% RS01 and 25% RS12 achieves a minimum interfacial transition zone width of 46 µm. Utilizing larger-particle-size RS in 3D printing effectively enhances its utilization rate while maintaining satisfactory printability and mechanical properties. Full article

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

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24 pages, 8891 KB

Open AccessArticle

Long-Term Strength Development and Microstructural Characteristics of High-Content Cemented Soil Under Seawater Exposure

by Haoqiang Pan, Wenjun Wang, Jie Zhou, Xiao Cheng and Guangyang Hu

Materials 2026, 19(7), 1477; https://doi.org/10.3390/ma19071477 - 7 Apr 2026

Abstract

High-content cemented soils are critical for modern geotechnical technologies (e.g., pre-bored precast piles), yet their long-term durability remains underexplored. This study investigates the 28- to 365-day mechanical and microstructural evolution of high-content cemented silty clay under freshwater and seawater curing via UCS, SEM, [...] Read more.

High-content cemented soils are critical for modern geotechnical technologies (e.g., pre-bored precast piles), yet their long-term durability remains underexplored. This study investigates the 28- to 365-day mechanical and microstructural evolution of high-content cemented silty clay under freshwater and seawater curing via UCS, SEM, MIP, and XRD. Under freshwater, cement content directly dictated strength, with the 8:2 mix reaching 24.31 MPa at 365 days. However, marginal efficiency analysis confirmed diminishing returns for excessive binder, establishing the 7:3 ratio as the optimal baseline. Seawater exposure induced a biphasic response: a 4.6% early strength gain at 28 days, followed by severe degradation (a 23.5% drop at 365 days). Concurrently, the failure mode shifted to macroscopic “pseudo-ductility,” with peak strain increasing from 2.37% to 3.04%. Crucially, a micro–macro inconsistency emerged: although seawater physically refined the pore structure (micropore proportion doubled to 30.2% at 90 days) via expansive salts filling mesopores, macroscopic strength declined. XRD confirmed this degradation coincides with severe long-term alkaline buffer (Ca(OH)₂) depletion. Consequently, lifecycle durability assessments for high-binder marine systems must not rely solely on physical metrics like porosity, but adopt a coupled multi-factor framework prioritizing chemical stability. Full article

(This article belongs to the Special Issue Sustainable Construction and Building Materials: Microstructure, Mechanical Performance, and Long-Term Durability)

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23 pages, 5671 KB

Open AccessArticle

Effect of Chemical Cross-Linking on Compatibility and Laboratory Performance of SBS/PE/EVA Ternary Composite Modified Asphalt

by Hong Zhang, Cheng Wang, Yiming Chen, Ning Li, Tao Zhou, Yu Mao and Yan Zhang

Materials 2026, 19(7), 1476; https://doi.org/10.3390/ma19071476 - 7 Apr 2026

Abstract

In response to the shortcomings still observed in polyethylene (PE)/ethylene-vinyl acetate (EVA)/styrene-butadiene-styrene (SBS) composite modified bitumen regarding storage stratification and low-temperature performance, this paper further introduces furfural extract, elemental sulphur, stabilisers and Z-6036 into this ternary system, and employs orthogonal design to screen [...] Read more.

In response to the shortcomings still observed in polyethylene (PE)/ethylene-vinyl acetate (EVA)/styrene-butadiene-styrene (SBS) composite modified bitumen regarding storage stratification and low-temperature performance, this paper further introduces furfural extract, elemental sulphur, stabilisers and Z-6036 into this ternary system, and employs orthogonal design to screen the additive ratios. Tests were conducted on conventional physical properties, rotational viscosity, dynamic shear rheology and bending beam rheology, focusing on the material’s temperature sensitivity, rheological behaviour, low-temperature creep resistance and phase characteristics. The modification effects were analysed using fluorescence microscopy, scanning electron microscopy and infrared spectroscopy. Compared with the control group composed of 4% PE, 4% EVA and 2% SBS, the samples obtained from the orthogonal design showed an increase in elongation at 5 °C ranging from 52.5% to 213.9%; the difference in softening points decreased from 35.2 °C to a minimum of 0.1 °C, indicating improved storage stability. The temperature sensitivity of all sample groups was reduced, with the optimal group achieving a VTS of −0.4413, representing a 46.7% improvement over the control group. At −12 °C, the m-values of all nine orthogonal samples were higher than those of the control group, with seven groups reaching m ≥ 0.3, indicating improved low-temperature stress relaxation capability. A comprehensive analysis of the experimental results indicates that the selected chemical additives are beneficial for optimising the dispersion state and compatibility of the SBS/PE/EVA ternary modified bitumen, whilst also balancing rheological properties and low-temperature crack resistance to a certain extent. Microscopic and spectroscopic analyses further suggest that internal interactions within the system have been enhanced and the phase distribution has become more uniform; however, the current evidence is insufficient to conclusively determine that a specific form of chemical cross-linking reaction has occurred. Full article

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

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16 pages, 7541 KB

Open AccessArticle

Controllable Preparation of Si₃N₄@MgSiN₂ Core–Shell Powders via a “Template Growth” Mechanism in NaCl-KCl Mixed Molten Salt

by Yiming Liu, Weiming Wang, Yong Mo, Lei Guo, Zheng Peng, Weide Wang and Qingsong Ma

Materials 2026, 19(7), 1475; https://doi.org/10.3390/ma19071475 - 7 Apr 2026

Abstract

Si₃N₄@MgSiN₂ composite powder with a core–shell structure was successfully synthesized via the in situ reaction between Mg and α-Si₃N₄ using a NaCl–KCl mixed molten salt in this study. The effects of process parameters, including the [...] Read more.

Si₃N₄@MgSiN₂ composite powder with a core–shell structure was successfully synthesized via the in situ reaction between Mg and α-Si₃N₄ using a NaCl–KCl mixed molten salt in this study. The effects of process parameters, including the molten salt system, reaction temperature, and Mg/Si₃N₄ mass ratio, on the morphology, phase composition, and microstructure of the coating layer were investigated. The results indicate that the reaction follows a “template growth” mechanism. Mg-containing species dissolve in the molten salt, diffuse to the surface of Si₃N₄ particles, and react with α-Si₃N₄, resulting in a relatively uniform MgSiN₂ layer at 1300 °C. The yield of MgSiN₂ layer exhibits a linear positive correlation with the Mg/Si₃N₄ mass ratio, enabling controllable microstructural regulation through adjustment of the starting materials composition. The core–shell powder forms a liquid phase at a relatively low temperature (approximately 1350 °C), demonstrating excellent sintering activity. This work provides a new material foundation for the fabrication of silicon nitride ceramics with high thermal conductivity. Full article

(This article belongs to the Section Advanced and Functional Ceramics and Glasses)

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23 pages, 4955 KB

Open AccessArticle

Preparation and Recovery Behavior of Lithium Chloride (LiCl) from Lithium Iron Phosphate (LiFePO₄) Cathode Active Materials via Hydrogen Reduction and CaCl₂-Assisted Thermal Chlorination

by Tae-Jun Jeon and Jei-Pil Wang

Materials 2026, 19(7), 1474; https://doi.org/10.3390/ma19071474 - 7 Apr 2026

Abstract

In this study, lithium was recovered from LiFePO₄ (LFP) cathode active materials through a two-step thermal process combining hydrogen reduction and chlorination roasting. Hydrogen reduction was conducted while varying temperature and holding time to promote oxygen removal from LFP and induce phase [...] Read more.

In this study, lithium was recovered from LiFePO₄ (LFP) cathode active materials through a two-step thermal process combining hydrogen reduction and chlorination roasting. Hydrogen reduction was conducted while varying temperature and holding time to promote oxygen removal from LFP and induce phase separation into Li₃PO₄ and iron phosphides (FeP and Fe₂P). Based on stoichiometric assessment using the degree of LFP decomposition and the reduction in oxygen moles, the optimal hydrogen-reduction condition was determined to be 900 °C for 1 h. Subsequently, CaCl₂ was selected as an appropriate chlorination agent using thermodynamic considerations, and the hydrogen-reduced product was reacted with CaCl₂ to convert Li₃PO₄ into water-soluble LiCl. The mass of LiCl produced was quantified as a function of reaction temperature. Water leaching enabled the separation of LiCl from the insoluble residues, resulting in an overall lithium recovery of 71.7%. Full article

(This article belongs to the Special Issue Advanced Materials, Processes and Systems for Electrochemical/Thermochemical Devices)

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19 pages, 12769 KB

Open AccessArticle

Research on the Microstructure and Performance Regulation of SLM 304 Steel Under Intermittent Deformation

by Huimin Tao, Linlin Ma, Bin Liao, Feng Liu, Yadong Li, Tingting Chen, Mingming Ding and Xiaomei Guo

Materials 2026, 19(7), 1473; https://doi.org/10.3390/ma19071473 - 7 Apr 2026

Abstract

This paper investigates the evolution of the microstructure, mechanical performances, and corrosion resistance of selective laser melting (SLM) 304 steel under different intermittent stretching deformation step sizes, revealing the underlying evolution patterns. The results indicate that the intermittent deformation step size significantly affects [...] Read more.

This paper investigates the evolution of the microstructure, mechanical performances, and corrosion resistance of selective laser melting (SLM) 304 steel under different intermittent stretching deformation step sizes, revealing the underlying evolution patterns. The results indicate that the intermittent deformation step size significantly affects the microstructure and performance of SLM 304 steel. Larger step sizes result in more complete molten pool contours, less deformation of grain and cellular structures, and a lower martensite volume fraction; smaller step sizes lead to distorted molten pools, fragmented grains, exacerbated cellular structure distortion, and increased martensite content. In terms of mechanical performances, tensile strength, nano-hardness, and elastic modulus decrease with increasing step size, while elongation increases accordingly. Corrosion resistance improves with larger step sizes, with specimens exhibiting more complete and thicker oxide films on the surface and superior pitting resistance; continuous stretching specimens exhibit the worst corrosion resistance, while the original specimens are the best. Intermittent deformation optimizes properties by regulating microstructure, providing a basis for the design of high-performance SLM 304 steel. This study provides theoretical support for the design and application of additive manufacturing stainless steel components, facilitating the engineering and industrial application of SLM technology in high-end equipment manufacturing. Full article

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

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41 pages, 16378 KB

Open AccessReview

Engineering Design Strategies for Boosting Photocatalytic Activity: Theory-to-Data-Driven Perspective

by Wilian Jesús Pech-Rodríguez, Nihat Ege Şahin and Gladis Guadalupe Suarez-Velázquez

Materials 2026, 19(7), 1472; https://doi.org/10.3390/ma19071472 - 7 Apr 2026

Abstract

Photocatalysts have emerged as a promising approach for the treatment of contaminated water, particularly for the removal of dyes and pharmaceutical residues that pose risks to human health. In addition, they can be employed for the generation of chemical fuels such as H [...] Read more.

Photocatalysts have emerged as a promising approach for the treatment of contaminated water, particularly for the removal of dyes and pharmaceutical residues that pose risks to human health. In addition, they can be employed for the generation of chemical fuels such as H₂ and oxidizers such as H₂O₂, which have been proposed as sustainable energy carriers to reduce reliance on fossil fuels. The first part of this brief review provides a detailed overview of the fundamental concepts of photocatalysis, including reaction pathways and reported mechanisms. The second part explores the main design strategies for enhancing photocatalytic performance, including morphology control and structural modification. Then, the third section highlights the benefits of theoretical modeling, including first-principles calculations and molecular simulations. The document culminates with a section on challenges and future perspectives, highlighting major issues in photocatalyst development such as large-scale synthesis, material stability, and reusability. This brief review is intended to provide young researchers with a concise understanding of the most effective strategies for enhancing photocatalytic performance, as well as the mechanisms influencing morphology and structural parameters. This work presents an integrated framework linking synthesis strategies, particle growth mechanisms, multidimensional nanostructures, in situ and operando characterization, and computational modeling to guide the rational design of next-generation photocatalysts. Full article

(This article belongs to the Special Issue Photocatalytic Materials and Technologies for Environmental Sustainability)

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27 pages, 758 KB

Open AccessReview

A Review of Research on the Valorization and Risk Management of Municipal Solid Waste Incineration Bottom Ash

by Yang Nan, Wenli Wang, Haozhe Chen, Jiapeng Guo, Yanqiang Chen and Du Yuan

Materials 2026, 19(7), 1471; https://doi.org/10.3390/ma19071471 - 7 Apr 2026

Abstract

Municipal solid waste incineration bottom ash (MSWIBA) represents both a resource opportunity and an environmental challenge in waste-to-energy systems. This comprehensive review examines MSWIBA’s physicochemical properties, heavy metal behavior, and applications in construction materials, alongside metal recovery techniques and risk mitigation strategies. The [...] Read more.

Municipal solid waste incineration bottom ash (MSWIBA) represents both a resource opportunity and an environmental challenge in waste-to-energy systems. This comprehensive review examines MSWIBA’s physicochemical properties, heavy metal behavior, and applications in construction materials, alongside metal recovery techniques and risk mitigation strategies. The research introduces an integrated management framework combining property assessment with coordinated stream processing to reconcile resource recovery with environmental safety. Future studies should focus on advanced analytical methods, hybrid processes, long-term immobilization mechanisms, and life cycle assessment. These innovations aim to transform MSWIBA into a sustainable resource, supporting circular economy principles and low-carbon development. Full article

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

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25 pages, 3472 KB

Open AccessArticle

Optimization of Punch Shaft Design for Reduced Punching Force and Enhanced Tool Life in S500MC Steel Sheet Forming

by Abdelwaheb Zeidi, Khaled Elleuch, Şaban Hakan Atapek, Jarosław Konieczny, Krzysztof Labisz and Janusz Ćwiek

Materials 2026, 19(7), 1470; https://doi.org/10.3390/ma19071470 - 7 Apr 2026

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Abstract

This study presents a comprehensive numerical and experimental investigation into the influence of punch shaft geometry on punching force and tool durability in the cold forming of S500MC steel sheets using an AISI D2 punch. Finite element analyses were conducted to evaluate the [...] Read more.

This study presents a comprehensive numerical and experimental investigation into the influence of punch shaft geometry on punching force and tool durability in the cold forming of S500MC steel sheets using an AISI D2 punch. Finite element analyses were conducted to evaluate the effects of varying punch shaft diameters on stress distribution, deformation behavior, and resultant punching forces. Experimental validation was performed through controlled punching tests, measuring force responses and assessing tool wear. The results demonstrate that optimizing the punch shaft diameter reduces the maximum punching force and minimizes stress concentrations, thereby enhancing tool life. Specifically, larger punch shaft diameters contribute to more uniform stress distribution and decreased risk of premature tool failure. These findings provide valuable insights for tooling design in high-strength steel sheet forming processes, enabling improved efficiency and cost-effectiveness in manufacturing operations. Full article

(This article belongs to the Special Issue Modeling and Optimization of Material Properties and Characteristics)

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21 pages, 9102 KB

Open AccessArticle

Optimization Design of Metakaolin-Based Geopolymer Solidification for Potassium Copper Hexacyanoferrate After Cs⁺ Adsorption Using Response Surface Methodology

by Yuqing Liao, Xingyu Yu, Xinyi Yuan, Jingsong Wang, Yao Yan and Gaoshang Ouyang

Materials 2026, 19(7), 1469; https://doi.org/10.3390/ma19071469 - 7 Apr 2026

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Abstract

This study employed a metakaolin-based geopolymer (GP) to solidify potassium copper hexacyanoferrate after its saturation with adsorbed Cs⁺. The experiment was designed using response surface methodology (RSM) in the Design–Expert 13 software, targeting the compressive strength and cumulative leaching fraction of [...] Read more.

This study employed a metakaolin-based geopolymer (GP) to solidify potassium copper hexacyanoferrate after its saturation with adsorbed Cs⁺. The experiment was designed using response surface methodology (RSM) in the Design–Expert 13 software, targeting the compressive strength and cumulative leaching fraction of the solidified form. A regression model was developed to achieve the multi-objective optimization of the comprehensive performance of the GP solidified product. Regression analysis identified the optimal mix proportion as Na₂O/Al₂O₃ = 0.84, SiO₂/Al₂O₃ = 2.8, and H₂O/Na₂O = 10.23. Under these conditions, the experimentally measured compressive strength was 23.41 MPa. The 42-day cumulative leaching fractions at 25 °C and 40 °C were 7.906 × 10⁻⁴ cm and 1.5923 × 10⁻³ cm, respectively, both significantly below the national standard threshold (Standard Code GB7023-2011) of 2.6 × 10⁻¹ cm. The percentage error remained within 10%, indicating strong agreement with predicted values. These results suggest that metakaolin-based GP exhibits promising potential for the immobilization of radionuclides. Full article

(This article belongs to the Section Materials Chemistry)

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21 pages, 6200 KB

Open AccessArticle

Prediction and Regulation of SCC’s Shrinkage Using the PSO-BPNN Model

by Tongyuan Ni, Lihua Shen, Shenghao Shen, Zaoyang Cai, Wen Chu, Chengshun Hu, Chenhui Jiang and Kai Jing

Materials 2026, 19(7), 1468; https://doi.org/10.3390/ma19071468 - 7 Apr 2026

Viewed by 65

Abstract

The shrinkage deformation is a significant risk to self-compacting concrete (SCC)-filled steel tube structures. It was essential to understand the concrete autogenous shrinkage strain before being regulated in order to determine compensation shrinkage measures. In this study, A PSO-BPNN model was constructed, which [...] Read more.

The shrinkage deformation is a significant risk to self-compacting concrete (SCC)-filled steel tube structures. It was essential to understand the concrete autogenous shrinkage strain before being regulated in order to determine compensation shrinkage measures. In this study, A PSO-BPNN model was constructed, which is based on the Particle Swarm Optimization-Back Propagation Neural Networks (PSO-BPNN), and the autogenous shrinkage strain of SCC was predicted based on PSO-BPNN before being regulated. Moreover, some experiments about compensating for shrinkage by expansion and by a combination of expansion and contraction were investigated. Based on this prediction, a series of experiments was conducted on the regulation of the shrinkage deformation of SCC for an actual bridge project. The results indicated that a good consistency of PSO-BPNN between predicted and measured values, demonstrating that PSO-BPNN is a model with high accuracy in predicting concrete autogenous shrinkage strain before regulation, and as a guidance for regulation to compensate for shrinkage. The prediction error was less than 10% for 28-day self-shrinkage, and the experimental workload was reduced. The PSO-BPNN is a convenient tool for predicting the shrinkage of SCC, enabling the determination of dosages of expansion agent and reducing shrinkage agent to achieve SCC’s shrinkage regulation. Full article

(This article belongs to the Special Issue Advanced Experimental Technology, Theory and Numerical Methods in Concrete Materials)

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1 pages, 316 KB

Open AccessCorrection

Correction: Rehman et al. Bergenia ciliate–Mediated Mixed-Phase Synthesis and Characterization of Silver-Copper Oxide Nanocomposite for Environmental and Biological Applications. Materials 2021, 14, 6085

by Fazal Ur Rehman, Rashid Mahmood, Manel Ben Ali, Amor Hedfi, Mohammed Almalki, Amine Mezni, Wajid Rehman, Sirajul Haq and Humma Afsar

Materials 2026, 19(7), 1467; https://doi.org/10.3390/ma19071467 - 7 Apr 2026

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Abstract

In the original publication [...] Full article

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22 pages, 2498 KB

Open AccessArticle

Mn(II) Complex with Rutin—Spectral Characteristic, Quantum-Chemical Calculations, Antioxidant and α-Amylase Inhibitory Activity

by Maciej Kozłowski, Monika Kalinowska, Mariola Samsonowicz, Grzegorz Świderski and Beata Kalska-Szostko

Materials 2026, 19(7), 1466; https://doi.org/10.3390/ma19071466 - 6 Apr 2026

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Abstract

Rutin is a naturally occurring flavonoid with well-documented antioxidant and pharmacological properties. In this study, a manganese(II) complex with rutin (Mn(II)-Rut) was synthesized in a solid state and characterized using FT-IR, Raman spectroscopy, thermogravimetric and elemental analysis, confirming its composition as C₂₇ [...] Read more.

Rutin is a naturally occurring flavonoid with well-documented antioxidant and pharmacological properties. In this study, a manganese(II) complex with rutin (Mn(II)-Rut) was synthesized in a solid state and characterized using FT-IR, Raman spectroscopy, thermogravimetric and elemental analysis, confirming its composition as C₂₇H₂₇O₁₆Mn₂·5H₂O. The IR spectra indicated that rutin coordinates manganese ions through the carbonyl group at the C4 position and the hydroxyl group at the C5 atom, as well as the catecholic system. The antioxidant potential of both Mn(II)-Rut and rutin was evaluated using several spectrophotometric assays. The Mn(II)-Rut complex showed stronger activity in most spectrophotometric assays than rutin, i.e., in ABTS assay, 50.37 ± 2.64% vs. 41.49 ± 1.38%; in CUPRAC assay, 0.468 ± 0.006 mM Trolox vs. 0.379 ± 0.007 mM Trolox; and FRAP assay, 0.201 ± 0.002 µM vs. 0.189 ± 0.003 µM. However, the DPPH assay complex showed a diminished effect compared with ligand (IC₅₀ 2.78 ± 0.13 µM vs. 0.98 ± 0.04 µM for rutin). Quantum-chemical calculations were also performed using the Gaussian09 program to determine the optimized geometric structures, electron charge distribution, and the energies of the HOMOs and LUMOs in the analyzed molecules in order to discuss the antioxidant mechanism of the molecules. Enzymatic assays demonstrated that the Mn(II) complex with rutin exhibited a stronger α-amylase inhibitory effect compared to free rutin, which showed the potential antidiabetic activity of the compound. The results suggest that the Mn(II) complex of rutin possesses better antioxidant and α-amylase inhibitory activity than the ligand alone. Full article

(This article belongs to the Special Issue Advanced Research of Organic Molecules and Materials for Modern Chemical and Biological Applications)

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31 pages, 2032 KB

Open AccessReview

Research Trends and Gaps in Construction Insulation Materials from Textile Waste and End-of-Life Wind Turbine Blades with Bio-Binders

by German Vela, António Figueiredo, Vítor Costa and Romeu Vicente

Materials 2026, 19(7), 1465; https://doi.org/10.3390/ma19071465 - 5 Apr 2026

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Abstract

Waste from the wind power and textile industries poses major environmental challenges. While the textile industry is a significant global contributor to waste, producing around 92 million tons of waste annually, and greenhouse gas emissions, wind power, although one of the cleanest energy [...] Read more.

Waste from the wind power and textile industries poses major environmental challenges. While the textile industry is a significant global contributor to waste, producing around 92 million tons of waste annually, and greenhouse gas emissions, wind power, although one of the cleanest energy sources during operation, still generates waste and associated CO₂ emissions, particularly associated with the end-of-life decommissioning of turbine blades. This waste can be reused, combined with bio-based binders, to reduce the construction sector’s long-term environmental impact. The present work identifies research trends and gaps in the use of these waste materials, either individually or combined, for the development of thermal and acoustic insulation solutions for the construction sector, by means of a combined bibliometric and content analysis of Scopus and Web of Science documents from 2014 to 2025. The study focuses on bibliometric indicators and reports on physical properties (thermal conductivity, density, mechanical strength, and acoustic performance) of the resulting composites, including those produced with bio-binders. Additionally, a qualitative review of life cycle assessment studies indicates that bio-based and waste-derived insulation materials can significantly reduce environmental impacts compared with conventional mineral or petrochemical insulators. Results reveal growing scientific interest in this subject, highlighting an annual publication growth of 5.09%. They emphasize the performance of natural textile fibers in thermal and acoustic insulation, the mechanical capacity of synthetic fibers, and the semi-structural potential of fiberglass composites. Meanwhile, bio-binders improve the upcycling of textile waste; however, they reveal a significant research gap in the integration of wind turbine blade waste into insulation composites. No indexed studies were found that simultaneously combine textile waste, blade-derived fibers, and bio-based binders in a single insulation system, despite projected cumulative blade waste of 43 million tons by 2050. These findings advocate hybrid innovations and standardized assessments to drive circular economy and low-carbon building solutions. Full article

(This article belongs to the Section Green Materials)

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5 pages, 191 KB

Open AccessEditorial

Advanced Experimental Technology, Theory and Numerical Methods in Geomaterials and Concrete Materials

by Wenhui Sun, Yifei Li, Runyu Liu and Shuyang Yu

Materials 2026, 19(7), 1464; https://doi.org/10.3390/ma19071464 - 5 Apr 2026

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Abstract

Geotechnical and concrete materials are used as core carriers for infrastructure construction [...] Full article

18 pages, 3687 KB

Open AccessArticle

Experimental Study on Rheological, Mechanical Properties and Microstructure of Ultra-High Performance Concrete (UHPC) Mixed with Steel Slag Powder

by Lei Liu, Hao Chen, Xinhua Cai, Jinyang Cui and Wei Guo

Materials 2026, 19(7), 1463; https://doi.org/10.3390/ma19071463 - 5 Apr 2026

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Abstract

In order to promote the high-quality utilization of solid waste—steel slag—this study prepared ground steel slag powder with specific surface areas of 400 m²/kg, 500 m²/kg and 600 m²/kg respectively. Different fineness levels of steel slag powder [...] Read more.

In order to promote the high-quality utilization of solid waste—steel slag—this study prepared ground steel slag powder with specific surface areas of 400 m²/kg, 500 m²/kg and 600 m²/kg respectively. Different fineness levels of steel slag powder were used to replace cement to prepare ultra-high performance concrete (UHPC), with replacement rates of 20%, 30% and 40% respectively. The effects of fineness and dosage of steel slag powder on the workability, mechanical properties and microstructure of UHPC were further investigated. The results show that the incorporation of steel slag powder can significantly reduce the yield stress and plastic viscosity of UHPC, thereby increasing its fluidity, but also decreasing its thixotropy. The tensile properties of UHPC mixed with steel slag powder were all superior to those of the reference group. The compressive strength of UHPC prepared by using steel slag powder with a specific surface area of 400 m²/kg or 600 m²/kg instead of 20% cement was higher than that of the reference group. The compressive strength of UHPC mixed with 600 m²/kg specific surface area steel slag powder was generally stronger at the same dosage. At the same fineness, the mechanical properties of UHPC decreased gradually with the increase in steel slag powder content. The recommended dosage for the steel slag powder with a specific surface area of 400 m²/kg is 20%, which results in the best comprehensive properties in UHPC. At this time, compared with the reference group, the compressive strength increased by 3.35%, and the tensile strength increased by 20.73%. Moreover, adequate fineness of the steel slag powder can be achieved without excessive grinding energy, which contributes to sustainability. Full article

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

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27 pages, 6248 KB

Open AccessArticle

Road Performance of Solid Waste-Based Cementitious Material-Stabilized Reclaimed Base Course Material

by Qi Ma, Jiuguang Geng, Peng Wei, Xijuan Xu, Zewen He, Zhen Wang and Hui Lan

Materials 2026, 19(7), 1462; https://doi.org/10.3390/ma19071462 - 5 Apr 2026

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Abstract

Large-scale pavement maintenance generates substantial amounts of reclaimed base course material (RBM), whose high-value reuse presents a critical challenge. Although cement is commonly used for stabilization, its high carbon footprint and shrinkage issues limit sustainability. This study proposes a 100% solid waste-based cementitious [...] Read more.

Large-scale pavement maintenance generates substantial amounts of reclaimed base course material (RBM), whose high-value reuse presents a critical challenge. Although cement is commonly used for stabilization, its high carbon footprint and shrinkage issues limit sustainability. This study proposes a 100% solid waste-based cementitious material (SWC) as an alternative stabilizer for pavement base layers containing high proportions of RBM. A comparative investigation was conducted between SWC-stabilized RBM (SSRBM) and ordinary Portland cement-stabilized RBM (CSRBM) regarding key road performance indicators. The results indicate that with 100% RBM, the 7-day compressive strength of SSRBM containing 4% SWC reaches 1.88 MPa, meeting the Chinese specification JTG/T 5521-2019. By incorporating 15% natural coarse aggregate, this strength can be increased by 35.4%. Furthermore, SSRBM demonstrates superior freeze–thaw resistance, with a freeze–thaw-retained unconfined compressive strength ratio of 93.9%, compared to 89.6% for CSRBM, and exhibits a lower drying shrinkage coefficient. Carbon emission analysis shows that the emissions per cubic meter of SSRBM are approximately 73% lower than those of CSRBM, presenting a viable and environmentally advantageous alternative for sustainable pavement construction. Full article

(This article belongs to the Special Issue Green and Sustainable Infrastructure Construction Materials (3rd Edition))

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14 pages, 11884 KB

Open AccessArticle

High-Temperature Isothermal Oxidation Behavior of Newly Developed Fe–Cr–Ni Austenite Stainless Steel

by Mohammed Nawaz Husain, Thangam Muniyandi, Bhuvaneshuwari Balaguru, Kamalan Kirubaharan Amirtharaj Mosas, Ashok Raja Chandrasekar and Dinesh Kumar Devarajan

Materials 2026, 19(7), 1461; https://doi.org/10.3390/ma19071461 - 5 Apr 2026

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Abstract

One of the significant causes of failure in aerospace engine components is high-temperature oxidation. Therefore, it is necessary to investigate the high-temperature oxidation behavior of newly fabricated structural materials for aerospace components. From this perspective, the isothermal oxidation behavior and kinetics of newly [...] Read more.

One of the significant causes of failure in aerospace engine components is high-temperature oxidation. Therefore, it is necessary to investigate the high-temperature oxidation behavior of newly fabricated structural materials for aerospace components. From this perspective, the isothermal oxidation behavior and kinetics of newly developed stainless steel (SS) 08X14H were investigated at 750, 950 and 1050 °C for up to 100 h in an air environment. The weight results demonstrate that oxidation in 08X14H increases with time and temperature and follows a parabolic rate law. Major spallation was observed in samples oxidized for 100 and 24 h at 950 °C and 1050 °C, respectively. Structural and morphological analysis of oxidized samples through X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) of the surface and cross section reveal the phases present and their distribution. The structural results confirm the formation of Fe₂O₃, Cr₂O₃, FeCr₂O₄ and intermediate (Cr, Fe)₂O₃ oxides in the oxidized samples. Surface morphologies reveal that the formation of a Cr₂O₃ layer effectively protects the material from further oxidation. At higher temperatures, the coarsening of Fe₂O₃ oxides takes place, which leads to the formation of loose and porous oxide scale with stress-induced cracks. The spallation of the outermost Fe₂O₃-rich oxide scale was observed, and the matrix is exposed during the extreme oxidation at 950 and 1050 °C for 100 and 50 h, respectively. The cross-sectional morphologies and elemental mapping results reveal a duplex oxide layer with an outermost Fe₂O₃ layer followed by an underlying layer of Cr₂O₃, (Cr, Fe)₂O₃ and FeCr₂O₄ spinel beneath the Fe₂O₃ layer. Full article

(This article belongs to the Section Metals and Alloys)

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27 pages, 4436 KB

Open AccessArticle

Effects of Crumb Rubber Content and Preparation Temperature on the Asphalt Performance and Fume Emissions of Deodorized Rubberized Asphalt

by Wenxiu Wu, Xiangzheng Fang, Yonglin Hu, Huiyi Jin, Yinyan Li, Yifei Sun, Wanyu Wu, Chao Li and Yingjun Jiang

Materials 2026, 19(7), 1460; https://doi.org/10.3390/ma19071460 - 5 Apr 2026

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Abstract

While rubberized asphalt with a crumb rubber content of 20% to 40% can improve asphalt performance, it also faces prominent issues such as increased construction viscosity and intensified fume emissions. Currently, systematic studies on high-content deodorized rubberized asphalt across different preparation temperatures remain [...] Read more.

While rubberized asphalt with a crumb rubber content of 20% to 40% can improve asphalt performance, it also faces prominent issues such as increased construction viscosity and intensified fume emissions. Currently, systematic studies on high-content deodorized rubberized asphalt across different preparation temperatures remain insufficient, particularly regarding the synergistic optimization of performance enhancement and fume emission control, including gaseous pollutants and particulate matter. To address this, deodorized crumb rubber (G-CR), a surface-treated crumb rubber produced by coating with a deodorizing agent, was introduced in this study and blended with base asphalt to prepare deodorized rubberized asphalt (G-CRA). Through laboratory binder tests, the coupled effects of crumb rubber content and preparation temperature (170–200 °C) on the conventional properties, rheological characteristics, and fume emissions of G-CRA were systematically analyzed. The results show that at 30% crumb rubber content and 190 °C preparation temperature, the asphalt binder achieves an optimal balance among penetration, ductility, and softening point, along with significantly improved high-temperature stability and aging resistance. Compared to conventional crumb rubber asphalt (CRA, without deodorant treatment), G-CRA achieves a significant reduction in fume emissions, with SO₂ reduction reaching up to 81%. This study demonstrates that deodorized crumb rubber can effectively synergize performance enhancement and gaseous emission control under high-content conditions, providing laboratory-level data support for the development of environmentally friendly rubberized asphalt. Full article

(This article belongs to the Special Issue Sustainable Pavement Materials: Design, Application and Performance Evaluation (Second Edition))

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12 pages, 6355 KB

Open AccessArticle

Comparison of Oxide Scale Morphology on FeAl-Based Alloy After Long-Term Oxidation in Air and Water Vapor at 700 °C

by Janusz Cebulski, Dorota Pasek, Maria Sozańska, Magdalena Popczyk, Jadwiga Gabor and Andrzej Swinarew

Materials 2026, 19(7), 1459; https://doi.org/10.3390/ma19071459 - 5 Apr 2026

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Abstract

The present study investigates the morphology, chemical composition, and phase constitution of oxide scales formed on the Fe40Al5Cr0.2TiB intermetallic alloy after long-term oxidation at 700 °C for 2000 h in air and water vapor environments. The results demonstrate the formation of an extremely [...] Read more.

The present study investigates the morphology, chemical composition, and phase constitution of oxide scales formed on the Fe40Al5Cr0.2TiB intermetallic alloy after long-term oxidation at 700 °C for 2000 h in air and water vapor environments. The results demonstrate the formation of an extremely thin oxide scale (≈300 nm), composed predominantly of α-Al₂O₃, which provides effective protection against further oxidation. The oxide layer exhibits locally heterogeneous morphology, including whisker-like structures and fine crystallites. Due to the very limited thickness of the oxide scale, significant challenges arise in the interpretation of microanalytical data. It is shown that the accelerating voltage strongly influences the effective information depth in SEM-EDS analysis, leading to a substantial contribution from the substrate even at low voltages. Monte Carlo simulations were used to support the interpretation of electron–matter interactions and to explain the observed discrepancies in chemical analysis. The study demonstrates that reliable characterization of ultrathin oxide scales requires careful optimization of SEM parameters and the combined use of complementary techniques, including EDS/WDS, XRD, and EBSD. The findings highlight the importance of methodological considerations in the analysis of thin oxide layers and provide guidance for the correct interpretation of experimental data in similar systems. Full article

(This article belongs to the Special Issue Achievements in Foundry Materials and Technologies (Second Edition))

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24 pages, 13924 KB

Open AccessArticle

Synthesis and Characterization of CaFe₂O₄: Catalytic and Bactericidal Evaluation at High Temperatures

by Daniel Eduardo Bernal Lozano, Miguel Andrés Perdomo Gutiérrez, Ailton José Moreira, Vinicius Marques Ferreira, João Otávio Donizette Malafatti, Elaine Cristina Paris and Miryam Rincón Joya

Materials 2026, 19(7), 1458; https://doi.org/10.3390/ma19071458 - 5 Apr 2026

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Abstract

CaFe₂O₄ is a p-type ferrite semiconductor of interest for photo-assisted environmental remediation due to its narrow band gap and high chemical stability. In this work, CaFe₂O₄ powders were synthesized via the Pechini polymeric precursor method and calcined [...] Read more.

CaFe₂O₄ is a p-type ferrite semiconductor of interest for photo-assisted environmental remediation due to its narrow band gap and high chemical stability. In this work, CaFe₂O₄ powders were synthesized via the Pechini polymeric precursor method and calcined between 550 and 850 °C to investigate the influence of calcination temperature on structural order and material properties. X-ray diffraction combined with Rietveld refinement revealed the progressive stabilization of the orthorhombic Pnma phase, accompanied by relaxation of the FeO₆ octahedral framework. Raman and FT-IR spectroscopies confirmed a significant increase in vibrational coherence with increasing calcination temperature, quantified by a nearly three-fold increase in the global Raman order parameter and phonon lifetimes. Nitrogen physisorption showed a modest specific surface area and a pore system dominated by interparticle meso–macroporosity, typical of thermally treated ferrites. Removal tests using ciprofloxacin under UV-A irradiation showed limited photo-assisted activity, while agar diffusion assays against Escherichia coli and Staphylococcus aureus revealed no inhibition halos, indicating the absence of detectable antibacterial activity under the experimental conditions employed. Overall, CaFe₂O₄ combines photo-assisted response with good structural stability, highlighting its potential as a chemically stable ceramic material with no detectable antibacterial activity under the tested conditions. Full article

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19 pages, 8434 KB

Open AccessArticle

One-Step Synthesis of Bamboo Biochar for Efficiency Adsorption of Tetracycline: Characterization, Kinetics and Cost–Benefit Analysis

by Qi Liao, Chengyang Cao, Qiming Zhang, Pei Jia and Lu Dong

Materials 2026, 19(7), 1457; https://doi.org/10.3390/ma19071457 - 5 Apr 2026

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Abstract

Tetracycline has been widely used as an efficient broad-spectrum antibiotic, while its long-term environmental pollution characteristics have gradually gained recognition and attention, highlighting the urgent need to identify a low-cost and effective method for removing tetracycline pollutants. This study aims to develop a [...] Read more.

Tetracycline has been widely used as an efficient broad-spectrum antibiotic, while its long-term environmental pollution characteristics have gradually gained recognition and attention, highlighting the urgent need to identify a low-cost and effective method for removing tetracycline pollutants. This study aims to develop a one-step bamboo-based biochar preparation method based on a KCl-ZnCl₂ molten salt system; the potential application of obtained bamboo-based biochar as a tetracycline adsorbent was characterized and analyzed. Results show that the biochar prepared at 900 °C possesses abundant microporous and mesoporous structures, with abundant surface functional groups. Also, it exhibits a composite type I/IV isotherm, with a specific surface area of 1305.91 m²·g⁻¹, a total pore volume of 0.944 cm³·g⁻¹, demonstrating excellent tetracycline adsorption capacity of 298.93 mg·g⁻¹. XRD analysis confirmed that increasing the activation temperature significantly enhanced the graphitization degree of the biochar, which is a key factor influencing its tetracycline adsorption performance. Kinetic studies indicated that the adsorption kinetic process was better described by the Elovich model and Freundlich isotherm. Furthermore, cost-effectiveness analysis revealed that the cyclic preparation cost of biochar via this technique could be reduced to 18.25 USD per kilogram owing to the low consumption characteristics of the KCl-ZnCl₂ molten salt, which represents a 93.4% reduction compared with conventional preparation methods, underscoring the economic applicability of this technology in the field of tetracycline removal. The findings of this study are expected to lay a foundation for the industrial preparation of low-cost, high-performance bamboo-based biochar for tetracycline removal. Full article

(This article belongs to the Special Issue From Waste to Value: Advanced Materials for Integrated Pollution Management and Circular Economy)

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19 pages, 1506 KB

Open AccessArticle

Optically Activated Superconductivity in MgB₂ via Electroluminescent GaP Inhomogeneous Phase

by Yao Qi, Duo Chen, Qingyu Hai, Xiaoyan Li and Xiaopeng Zhao

Materials 2026, 19(7), 1456; https://doi.org/10.3390/ma19071456 - 5 Apr 2026

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Abstract

Experimental results suggest a feasible strategy for tuning the superconducting properties of MgB₂ through the incorporation of an electroluminescent inhomogeneous phase. By introducing GaP electroluminescent inhomogeneous phases into MgB₂, the effects of emission intensity variation on the sample structure, superconducting [...] Read more.

Experimental results suggest a feasible strategy for tuning the superconducting properties of MgB₂ through the incorporation of an electroluminescent inhomogeneous phase. By introducing GaP electroluminescent inhomogeneous phases into MgB₂, the effects of emission intensity variation on the sample structure, superconducting transition temperature, electrical transport behavior, and magnetic properties were systematically investigated. The results show that, at a fixed GaP addition level, the superconducting transition temperature T_c increases steadily from 38.2 K to 39.6 K with increasing emission intensity of the inhomogeneous phase, corresponding to a maximum enhancement of approximately 1.4 K. Meanwhile, the zero-resistance temperature shifts upward synchronously, indicating that the entire superconducting transition region moves toward higher temperatures. Raman measurements show that the peak position and linewidth of the E_2g phonon mode evolve systematically with emission intensity, while the electron–phonon coupling parameter λ exhibits a trend consistent with that of T_c. In addition, the nanoscale dispersed distribution of the GaP inhomogeneous phase, together with the interface/defect structures it introduces, appears to promote sample densification and enhance flux pinning, resulting in an increase in the critical current density J_c by approximately 69% at 20 K in self-field and an enhancement of the irreversibility field H_irr by about 31.5%. These results suggest that, beyond the effect of static inhomogeneous-phase incorporation, the luminescence-activated state under bias excitation is likely involved in modulating the superconducting response of MgB₂. This work provides a new experimental perspective for synergistically regulating the properties of conventional superconductors through the combined effects of inhomogeneous phases and excited states. Full article

(This article belongs to the Special Issue Advances in Superconducting Materials: From Structure and Properties to Applications)

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18 pages, 10550 KB

Open AccessArticle

Transparent Conductive Copper-Doped Zinc Oxide (ZnO:Cu) Thin Films: PVco-D Fabrication and Applications in Perovskite Solar Cells

by Mateusz Mientki, Anna Zawadzka, Magdalena Kowalska, Michał Zawadzki, Amal Tarbi, Bouchta Sahraoui and Przemysław Płóciennik

Materials 2026, 19(7), 1455; https://doi.org/10.3390/ma19071455 - 5 Apr 2026

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Abstract

Indium Tin Oxide (ITO) is one of the most widely used ohmic materials for fabricating ohmic layers in thin-film solar cells. ITO thin layers have reached almost the maximum theoretical conductivity and the lowest practical resistivity. Along with indium’s toxic environmental impact and [...] Read more.

Indium Tin Oxide (ITO) is one of the most widely used ohmic materials for fabricating ohmic layers in thin-film solar cells. ITO thin layers have reached almost the maximum theoretical conductivity and the lowest practical resistivity. Along with indium’s toxic environmental impact and the high cost of materials, these are the reasons why new materials for efficient, cheaper thin-film transparent ohmic layers are being examined. One of those materials is copper-doped zinc oxide (ZnO:Cu). In this paper, we present a new approach to copper-doped zinc oxide fabrication methods, based on the modern authorial Physical Vapor Co-Deposition technique, which involves optimizing Cu concentration to fine-tune crystal structure, optical band gap, and electrical properties, creating n-type TCOs essential for efficient charge transport in next-generation thin films perovskite solar cells. Full article

(This article belongs to the Special Issue Advances in Solar Cell Materials and Structures—Second Edition)

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23 pages, 25334 KB

Open AccessArticle

Oxidation and Wear Behaviors of GH3039 Nickel-Based Alloy After Borochromizing

by Lairong Xiao, Haitao Dong, Jiarui Li, Shaofu Xu, Yuxiang Jiang, Zhenwu Peng, Xiaojun Zhao and Zhenyang Cai

Materials 2026, 19(7), 1454; https://doi.org/10.3390/ma19071454 - 5 Apr 2026

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Abstract

GH3039 nickel-based alloy, as a key material for thermocouple protection tubes, is susceptible to wear and oxidation failure in high-temperature kiln environment. To address this, boronized, chromized and borochromized coatings were prepared on GH3039 substrate, and the friction-wear properties and high-temperature oxidation resistance [...] Read more.

GH3039 nickel-based alloy, as a key material for thermocouple protection tubes, is susceptible to wear and oxidation failure in high-temperature kiln environment. To address this, boronized, chromized and borochromized coatings were prepared on GH3039 substrate, and the friction-wear properties and high-temperature oxidation resistance of both the substrate and the coatings were systematically characterized. The results show that the borochromized coating, benefiting from the synergistic effect of its relatively high surface hardness and the boric acid lubricating film formed during the wear process, reduces the wear rate by 84.07% (to 1.44 × 10⁻⁵ mm³·N⁻¹·m⁻¹). Meanwhile, it exhibits the optimal oxidation resistance due to its dense Cr-rich layer, which can inhibit oxygen diffusion and supply chromium for protective Cr₂O₃ film. After 100 h of oxidation at 950 °C, its oxidation weight gain is reduced by 78.68% compared with the boronized sample (to 1.20 mg/cm²). Full article

(This article belongs to the Special Issue Advances in Functional Coatings and Films for Thermal, Wear and Corrosion Protection)

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16 pages, 5345 KB

Open AccessArticle

Precise Pressure Control for Screw Extrusion 3D Printing of PP-GF Composites Based on Inverse Model Feedforward and Variable Structure Feedback

by Yunlong Ma, Xiping Li, Nan Ma, Youqiang Yao, Sisi Wang and Zhonglue Hu

Materials 2026, 19(7), 1453; https://doi.org/10.3390/ma19071453 - 5 Apr 2026

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Abstract

Addressing challenges such as the non-Newtonian fluid characteristics of melt, significant system hysteresis, and rheological thermal drift in large-scale glass fiber-reinforced polypropylene (PP-GF) screw-extrusion additive manufacturing (SEAM), this paper proposes a composite pressure control strategy based on inverse model feedforward and variable-structure feedback [...] Read more.

Addressing challenges such as the non-Newtonian fluid characteristics of melt, significant system hysteresis, and rheological thermal drift in large-scale glass fiber-reinforced polypropylene (PP-GF) screw-extrusion additive manufacturing (SEAM), this paper proposes a composite pressure control strategy based on inverse model feedforward and variable-structure feedback (VSFC-Smith). This strategy establishes a dynamic pressure benchmark through an inverse rheological model, utilizes a Smith predictor to compensate for time delay, and introduces dead-zone variable-structure feedback to smoothly suppress thermal drift. Experimental results demonstrate that, compared to traditional PID (Proportional-Integral-Derivative) controller, the VSFC-Smith strategy reduces the step pressure overshoot from 23.37% to 17.37%, decreases steady-state screw speed fluctuation by approximately 50%, and limits the error within ±0.04 MPa during complex trajectory tracking. In practical molding validation, this strategy effectively suppressed surface ripples, reducing the surface roughness (Sa) by 14.5% to 124.41 μm; simultaneously, the Z-directional interlayer tensile strength reached 12.63 MPa (a 22.5% improvement compared to open-loop control). This study successfully overcomes the limitations of traditional high-gain feedback, achieving synergistic optimization of the macroscopic morphology and microscopic mechanical properties of composite parts. Full article

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

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24 pages, 4258 KB

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Axial Hysteretic Mechanical Characteristics of Wire Rope Isolators and Parameter Identification with a Novel Algebraic Closed-Form Model

by Gangwei Mei, Yongsheng He, Mengnan Dai, Longyun Zhou, Xiongliang Yao, Jun Shen and Chunhai Li

Materials 2026, 19(7), 1452; https://doi.org/10.3390/ma19071452 - 5 Apr 2026

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Abstract

Wire rope isolators (WRIs) exhibit typical nonlinear and asymmetric hysteretic behavior, with their mechanical performance being significantly influenced by the coupled effects of multiple parameters. This study investigates the dynamic response of large-sized spiral WRIs under axial loading. Within the framework of an [...] Read more.

Wire rope isolators (WRIs) exhibit typical nonlinear and asymmetric hysteretic behavior, with their mechanical performance being significantly influenced by the coupled effects of multiple parameters. This study investigates the dynamic response of large-sized spiral WRIs under axial loading. Within the framework of an asymmetric hysteresis model, a novel algebraic closed-form formulation is adopted for parameter identification and numerical simulation. Furthermore, a characteristic parameter, A, is introduced to quantify the unique mechanical behavior induced by the structural configuration of WRIs. Five types of large-sized spiral WRIs are selected as test specimens. For each WRI, tests are conducted under 30 distinct working conditions, yielding a total of 150 cyclic loading tests across all scenarios. By systematically varying the displacement amplitude, loading frequency, and preloading pressure, the influences of these key parameters on the dynamic characteristics of WRIs are comprehensively analyzed. These characteristics encompass the axial hysteresis loop shape, energy dissipation capacity, equivalent viscous damping, and average secant stiffness. The results indicate that these three loading parameters exert substantial effects on the mechanical properties of large-sized WRIs. Additionally, the simulated hysteresis curves derived from the identified parameters exhibit excellent agreement with the experimental observations. Compared with conventional mechanical models, the proposed algebraic closed-form model demonstrates slightly higher fitting accuracy, thereby validating its effectiveness and applicability in characterizing the mechanical behavior of large-sized WRIs. This research provides a crucial reference for the engineering application of large-sized spiral WRIs and facilitates the broader adoption of the proposed modeling approach. Full article

(This article belongs to the Section Mechanics of Materials)

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16 pages, 5952 KB

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Influence of Prosthetic Substrate, Cement, and Opaquer Liner on Color Matching of Translucent Zirconia- and Lithium-Based Ceramics

by Beata Dejak, Bartłomiej Konieczny, Agata Szczesio-Wlodarczyk and Wioleta Stopa

Materials 2026, 19(7), 1451; https://doi.org/10.3390/ma19071451 - 5 Apr 2026

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Abstract

The aim of this study was to evaluate the influence of prosthetic substrate type, resin cement shade, and opaquer liner application on the translucency and color matching of translucent zirconia- and lithium-based ceramics. Four A2-shade zirconia materials (Katana HTML Plus, STML, UTML, and [...] Read more.

The aim of this study was to evaluate the influence of prosthetic substrate type, resin cement shade, and opaquer liner application on the translucency and color matching of translucent zirconia- and lithium-based ceramics. Four A2-shade zirconia materials (Katana HTML Plus, STML, UTML, and YML), with and without an opaquer liner, lithium disilicate ceramics (Amber Mill LT and HT), and zirconia-reinforced lithium silicate (Celtra Duo) were investigated. Monolithic crowns and standardized rectangular specimens were fabricated using CAD/CAM technology and cemented with neutral, warm-shade, and opaque try-in pastes onto A2-shade composite resin and cobalt–chromium substrates. Color measurements were performed using a digital colorimeter based on the CIE L*a*b* system. Translucency parameters (TPs) and color differences (ΔE) relative to the A2 reference shade were calculated. Lithium-based ceramics exhibited significantly higher translucency than zirconia materials. Application of the opaquer liner on intaglio surface of crowns reduced their translucency. On A2-shade substrates, translucent zirconia luted with neutral or warm-shade paste demonstrated the most favorable color compatibility. In contrast, opaque try-in paste resulted in clinically unacceptable color deviations and loss of optical depth. On metallic substrates, most materials exhibited pronounced gray discoloration and substantial color mismatch, particularly lithium disilicate ceramics. These findings indicate that ceramic type, substrate color, opaquer liner application, and resin cement shade significantly influence the optical performance and final color outcome of all-ceramic restorations. Full article

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

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24 pages, 4828 KB

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Research on Multiaxial Random Vibration Fatigue Assessment Method for Vehicle-Mounted Equipment Based on IEC 61373 Standard

by Zhixiang Luo, Chengrui Guang, Yi Liu, Zhongcheng Hu and Ji Fang

Materials 2026, 19(7), 1450; https://doi.org/10.3390/ma19071450 - 4 Apr 2026

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Abstract

At present, most of the research methods for vibration fatigue of welded structures mainly focus on uniaxial stress, ignoring the influence of shear stress. To this end, by combining the ASME structural stress method with the random and vibration analysis theory outlined in [...] Read more.

At present, most of the research methods for vibration fatigue of welded structures mainly focus on uniaxial stress, ignoring the influence of shear stress. To this end, by combining the ASME structural stress method with the random and vibration analysis theory outlined in the IEC 61373 standard, a new method for evaluating the fatigue life of multi-axis random vibration problems in the frequency domain has been proposed. This method extends the structural stress method to multi-axis scenarios to accurately extract the local multi-axis structural stress state at the weld toe. Its advantage lies in the fact that it not only accounts for the influence of load frequency distribution and structural modal vibrations on fatigue life, but also incorporates the effect of local multiaxial stress conditions in the weld on fatigue life. Additionally, it includes corrections for non-proportional multiaxial stress conditions, resulting in fatigue assessment results that more closely reflect actual conditions. It was validated by comparing the local multiaxial stress, phase difference between shear and normal stress, and equivalent structural stress power spectrum of 0° and 30° fillet welded specimens with test results. Subsequently, it was applied to a multiaxial random vibration fatigue assessment of a vehicle-mounted electrical cabinet with experimental verification. The results indicate that fatigue life estimates based on a multi-axis stress state are lower than those obtained using a uniaxial method. Compared to traditional uniaxial methods, the multi-axis fatigue life estimates show a significant reduction ranging from 4.20% to 88.35%, effectively accounting for damage caused by shear stress. The fatigue assessment results are more closely aligned with experimental data, thereby validating the effectiveness of the proposed new method. The frequency-domain multiaxial random vibration fatigue assessment method proposed in this article provides a new technology for the design and evaluation of welded structures of vehicle-mounted equipment in rail vehicles. This method reduces costs during the design phase of rail vehicles, offering positive economic implications. Full article

(This article belongs to the Special Issue Design, Mechanical Properties, and Fatigue Behavior of Materials, Welding Joints and Structures)

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18 pages, 6573 KB

Open AccessArticle

Microstructure and Properties of Micro/Nano-Scale (TiB₂ + TiC)/Al Composites Prepared by Ti-B₄C Reactive Sintering and Spark Plasma Sintering

by Wenchao Huang, Dongting Li, Renquan Wang and Ying Liu

Materials 2026, 19(7), 1449; https://doi.org/10.3390/ma19071449 - 4 Apr 2026

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Abstract

In this work, micro/nano-scale (TiB₂ + TiC)/Al composites with reinforcement contents ranging from 0 to 30 wt.% were fabricated by the combination of Ti-B₄C reactive sintering and spark plasma sintering (SPS). The results indicate that a sintering temperature of 1400 [...] Read more.

In this work, micro/nano-scale (TiB₂ + TiC)/Al composites with reinforcement contents ranging from 0 to 30 wt.% were fabricated by the combination of Ti-B₄C reactive sintering and spark plasma sintering (SPS). The results indicate that a sintering temperature of 1400 °C is essential for achieving a complete reaction between Ti and B₄C, successfully producing a bimodal TiB₂-TiC reinforcement consisting of nano-scale and micro-scale particles. Microstructure analysis reveals that the addition of micro/nano-scale TiB₂ and TiC ceramic particles significantly refines the grain size of the Al matrix from 11.52 μm in pure Al to 1.09 μm in the 30 wt.% (TiB₂ + TiC)/Al composite. As the TiB₂ and TiC contents increase, Vickers hardness and compressive yield strength increase progressively, while the uniform compressive plastic strain first increases and then decreases. The 20 wt.% (TiB₂ + TiC)/Al composite demonstrates the optimal comprehensive properties, with a compressive yield strength of 196.4 ± 6.1 MPa, an ultimate strength of 914.6 ± 20.1 MPa, and a uniform plastic strain of ~73.2%, as well as minimal wear rates of (3.143 ± 0.194) × 10⁻⁴ mm³/(N·m), 1.676 ± 0.251× 10⁻³ mm³/(N·m) and (3.093 ± 0.335) × 10⁻³ mm³/(N·m) at 1 N, 3 N, and 5 N, respectively. This improvement stems from the combined effects of grain refinement, dispersion strengthening, enhanced load-bearing capacity and reduced adhesive wear via the TiB₂ and TiC reinforcements. Full article

(This article belongs to the Section Advanced Composites)

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