Materials

13 pages, 4969 KiB

Open AccessArticle

Thermoelectric Properties of NbCoNi_xSn (x = 0–1)

by Moritz Thiem, Ruijuan Yan, Anke Weidenkaff and Wenjie Xie

Materials 2025, 18(13), 3189; https://doi.org/10.3390/ma18133189 (registering DOI) - 5 Jul 2025

The half-Heusler (HH) compound NbCoSn; with 18 valence electrons; is a promising thermoelectric (TE) material due to its favourable electrical properties and excellent thermal and chemical stability. Enhancing its TE performance typically involves doping and microstructure engineering. In this study; Ni was introduced [...] Read more.

The half-Heusler (HH) compound NbCoSn; with 18 valence electrons; is a promising thermoelectric (TE) material due to its favourable electrical properties and excellent thermal and chemical stability. Enhancing its TE performance typically involves doping and microstructure engineering. In this study; Ni was introduced into NbCoSn to form NbCoNi_xSn (x = 0–1); and the effects of Ni content on the microstructure and TE properties were systematically investigated. At low doping levels (x ≤ 0.05); Ni occupies interstitial sites; forming NbCoNi_xSn solid solutions. At higher concentrations (x > 0.05); full-Heusler (FH) secondary phases emerge; resulting in HH–FH composites. The introduction of Co/Ni interstitials enhances TE performance by creating in-gap electronic states and increasing phonon scattering through point defects. A clear structural transition from HH to FH phases is observed with increasing Ni content. The highest figure of merit; ZT ≈ 0.52 at 975 K; was obtained for NbCoNi_0.05Sn; comparable to the best values reported for this system. Full article

(This article belongs to the Special Issue Synergy in Polyphase Materials: Harnessing the Power of Glass and Ceramics)

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16 pages, 3245 KiB

Open AccessArticle

Properties of Selected Additive Materials Used to Increase the Lifetime of Tools for Crushing Unwanted Growths Using Hardfacing by Welding Technology

by Miroslava Ťavodová, Monika Vargová, Dana Stančeková, Anna Rudawska and Arkadiusz Gola

Materials 2025, 18(13), 3188; https://doi.org/10.3390/ma18133188 (registering DOI) - 5 Jul 2025

Abstract

This article focuses on the possibilities of increasing the service life of tools for crushing unwanted growths. One way to increase their service life is to increase the hardness and resistance to abrasive wear of exposed surfaces of the tool, which are their [...] Read more.

This article focuses on the possibilities of increasing the service life of tools for crushing unwanted growths. One way to increase their service life is to increase the hardness and resistance to abrasive wear of exposed surfaces of the tool, which are their face and back. At the same time, however, care must be taken to ensure that the shape and weight of the tool is not altered after the additive has been hardfaced on. Thus, the tool was first modified by removing the material by milling from the face and back. Subsequently, two surfacing materials, namely UTP 690 and OK WearTrode 55, were chosen and hardfaced by welding onto the pre-prepared surfaces. After hardfacing by welding, the tools were ground to their original shape and their weight was measured. Subsequently, the tool was sawn, and specimens were created for Rockwell hardness evaluation, material microstructure and for abrasive wear resistance testing as per ASTM G133-95. The OK WearTrode 55 electrode is a hardfacing electrode that produces weld metal with a high-volume fraction of fine carbides in a martensitic matrix. Better results were achieved by the UTP 690 hardfacing material. The hardness was 3.1 times higher compared to the base tool material 16MnCr5 and 1.2 times higher than the OK WearTrode 55 material. The abrasive wear resistance was 2.76 times higher compared to 16MnCr5, and 1.14 times higher compared to the OK WearTrode 55 material. The choice of a suitable pre-treatment for the tool and the selection and application of such additional material, which with its complex properties better resists the effects of the working environment, is a prerequisite for increasing the service life of tools working in forestry. Full article

(This article belongs to the Special Issue New Trends in Mechanical and Tribological Properties of Materials and Components)

34 pages, 947 KiB

Open AccessSystematic Review

The Impact of Environmental and Material Factors on Fluoride Release from Metal-Modified Glass Ionomer Cements: A Systematic Review of In Vitro Studies

by Sylwia Klimas, Sylwia Kiryk, Jan Kiryk, Agnieszka Kotela, Julia Kensy, Mateusz Michalak, Zbigniew Rybak, Jacek Matys and Maciej Dobrzyński

Materials 2025, 18(13), 3187; https://doi.org/10.3390/ma18133187 (registering DOI) - 5 Jul 2025

Abstract

Objective: Fluoride is widely recognized for its preventive role against secondary caries. This systematic review aimed to evaluate how environmental and material factors influence fluoride ion release from metal-reinforced glass ionomer cements. Methods: A structured literature search was performed in March 2025 across [...] Read more.

Objective: Fluoride is widely recognized for its preventive role against secondary caries. This systematic review aimed to evaluate how environmental and material factors influence fluoride ion release from metal-reinforced glass ionomer cements. Methods: A structured literature search was performed in March 2025 across PubMed, Scopus, and Web of Science databases. Search terms included combinations of fluoride release AND glass ionomer AND silver OR zinc OR strontium OR copper. The study selection process followed PRISMA 2020 guidelines and was organized using the PICO framework. Out of 281 initially identified records, 153 were screened based on titles and abstracts. After applying predefined eligibility criteria, 23 studies met the inclusion requirements and were included in the qualitative analysis. Results: Among the 23 included publications, 12 involved glass ionomers modified with silver, and 6 of these reported an increase in fluoride release. Seven studies focused on zinc-modified cements, and four examined materials reinforced with strontium. Conclusions: The addition of strontium, titanium oxide, silver nanoparticles, or zirconium oxide increases the release of fluoride ions, while sintered silver reduces it. There is a great discrepancy among researchers regarding the effect of the addition of zinc oxide and its appropriate amount in the glass ionomer material. Full article

(This article belongs to the Special Issue Advanced Bioactive Materials and Bulk-Fill Composite Resins in Dental Restorative)

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25 pages, 5828 KiB

Open AccessArticle

Study on Performance and Aging Mechanism of Rubber-Modified Asphalt Under Variable-Intensity UV Aging

by Qian Liu, Fujin Hou, Dongdong Ge, Songtao Lv and Zihao Ju

Materials 2025, 18(13), 3186; https://doi.org/10.3390/ma18133186 (registering DOI) - 5 Jul 2025

Abstract

Prolonged ultraviolet (UV) exposure accelerates aging and degradation, while conventional constant-intensity UV simulations do not reflect the variable nature of outdoor radiation. Aging duration and film thickness are both key factors affecting Rubber-Modified Asphalt (RMA), but how their combination influences RMA remains unclear. [...] Read more.

Prolonged ultraviolet (UV) exposure accelerates aging and degradation, while conventional constant-intensity UV simulations do not reflect the variable nature of outdoor radiation. Aging duration and film thickness are both key factors affecting Rubber-Modified Asphalt (RMA), but how their combination influences RMA remains unclear. To address this limitation, this research employed accelerated aging experiments under variable-intensity UV radiation to investigate the performance and aging mechanism of RMA across different aging durations and asphalt film thicknesses. Rheological properties were analyzed through rheological tests, and the UV aging mechanisms of RMA were revealed using FTIR and SEM. The results revealed that crumb rubber improved RMA’s UV aging resistance, including high-temperature performance, fatigue life, and low-temperature cracking resistance. Aging effects were more influenced in RMA with thinner films under prolonged UV exposure. After nine cycles of ultraviolet aging, the rutting resistance, elastic recovery, fatigue life, and low-temperature cracking resistance of RMA with a 1 mm film thickness were 1.33, 1.11, 0.54, and 0.67 times, respectively, those of RMA with a 2 mm film thickness subjected to three UV aging cycles. RMA demonstrated comparable high-temperature performance and elastic recovery under UV aging conditions corresponding to a 1.5 mm film thickness aged for three cycles and a 2.0 mm film thickness aged for six cycles, as well as a 1.0 mm film thickness aged for six cycles and a 1.5 mm film thickness aged for nine cycles. FTIR showed that the increased activity of C=C and C-H under photo-oxidative aging caused a greater impact on the carbonyl groups than the sulfoxide groups. Under high-intensity UV radiation, RMA with thinner films exhibited greater rubber powder detachment, increased surface oxidation, and a substantial widening of cracks. The rubber powder absorbed UV radiation, enhancing the stability of RMA. The maximum crack width of the 1 mm NA was twice that of RMA. These provided insight into the microstructural pattern of cracking resistance degradation caused by aging. This research provides theoretical support for the optimization of the anti-aging performance of RMA. Full article

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

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24 pages, 5447 KiB

Open AccessArticle

Impact of Early-Age Curing and Environmental Conditions on Shrinkage and Microcracking in Concrete

by Magdalena Bacharz, Kamil Bacharz and Wiesław Trąmpczyński

Materials 2025, 18(13), 3185; https://doi.org/10.3390/ma18133185 (registering DOI) - 5 Jul 2025

Abstract

This study analyzed the effects of curing and maturation on the formation of shrinkage strain and destructive processes in concrete. Experimental tests were performed on commonly used concrete, class C30/37, with basalt aggregate and blast furnace cement tested: at constant temperature after water [...] Read more.

This study analyzed the effects of curing and maturation on the formation of shrinkage strain and destructive processes in concrete. Experimental tests were performed on commonly used concrete, class C30/37, with basalt aggregate and blast furnace cement tested: at constant temperature after water curing, at constant temperature without water curing, and under cyclically changing temperature without prior curing. Shrinkage strain was measured for 46 days with an extensometer on 150 × 150 × 600 mm specimens, and the acoustic emission (AE) method was used to monitor microcracks and processes in concrete in real time. The results were compared with the model according to EN 1992-1-1:2023. It was found that this model correctly estimates shrinkage strain for wet-curing concrete, but there are discrepancies for air-dried concrete, regardless of temperature and moisture conditions (constant/variable). Correlation coefficients between shrinkage strain increments and process increments in early-age concrete are proposed. Correlations between shrinkage strain and destructive processes occurring in concrete were confirmed. It was found that by using correlation coefficients, it is possible to estimate internal damage in relation to shrinkage strain. The results indicate the need to develop guidelines for estimating shrinkage strain in non-model environmental conditions and demonstrate the usefulness of the nondestructive AE method in diagnosing early damage, especially in concrete structures exposed to adverse service conditions. Full article

(This article belongs to the Collection Concrete and Building Materials)

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28 pages, 8350 KiB

Open AccessArticle

A New Design Methodology of Asphalt Mixture Dynamic Modulus Based on Pavement Response

by You Huang, Boxiong Feng, Xin Yang, Minxiang Cheng and Zhaohui Liu

Materials 2025, 18(13), 3184; https://doi.org/10.3390/ma18133184 (registering DOI) - 5 Jul 2025

Abstract

The design of asphalt mixture has, for a long time, been an empirical and proof process, causing the mismatch between material design and pavement structure design. To enhance the rationality of asphalt pavement design, this study seeks a path to bridge the gap [...] Read more.

The design of asphalt mixture has, for a long time, been an empirical and proof process, causing the mismatch between material design and pavement structure design. To enhance the rationality of asphalt pavement design, this study seeks a path to bridge the gap between asphalt mixture modulus and structural behavior. Firstly, pavement models with different base rigidities, including cement concrete base, cement-treated granular base, and granular base, were constructed to calculate the pavement responses under different dynamic modulus master curve parameters. The influence of master curve parameters on critical pavement responses was identified by the response surface method (RSM). Furthermore, a Whale Optimization Algorithm–Back Propagation (WOA-BP) artificial-neural-network-based pavement response prediction model was established. Then, a database mapping over 100 thousand pavement responses and dynamic modulus master curve parameters was built for determining the dynamic modulus master curve parameters by optimizing the pavement responses. The results show that the impacts of dynamic modulus master curve parameters on critical pavement responses depend on pavement structures. In general, parameter δ has the greatest impact, followed by α, while the effects of β and γ are relatively small. The Artificial Neural Network (ANN) performance prediction model, optimized by the WOA algorithm, has a high accuracy. The methodology for determining the dynamic modulus master curve parameter based on the critical response of pavement was successfully implemented. The findings can bridge the gap between material design and structure design of asphalt pavement and provide a basis for more accurate and reasonable asphalt pavement design. Full article

(This article belongs to the Special Issue Machine Learning, Health Monitoring, and Numerical Simulation of Civil Engineering Materials)

17 pages, 5457 KiB

Open AccessArticle

Multiphysics Modeling of Heat Transfer and Melt Pool Thermo-Fluid Dynamics in Laser-Based Powder Bed Fusion of Metals

by Tingzhong Zhang, Xijian Lin, Yanwen Qin, Dehua Zhu, Jing Wang, Chengguang Zhang and Yuchao Bai

Materials 2025, 18(13), 3183; https://doi.org/10.3390/ma18133183 (registering DOI) - 5 Jul 2025

Abstract

Laser-based powder bed fusion of metals (PBF-LB/M) is one of the most promising additive manufacturing technologies to fabricate complex-structured metal parts. However, its corresponding applications have been limited by technical bottlenecks and increasingly strict industrial requirements. Process optimization, a scientific issue, urgently needs [...] Read more.

Laser-based powder bed fusion of metals (PBF-LB/M) is one of the most promising additive manufacturing technologies to fabricate complex-structured metal parts. However, its corresponding applications have been limited by technical bottlenecks and increasingly strict industrial requirements. Process optimization, a scientific issue, urgently needs to be solved. In this paper, a three-phase transient model based on the level-set method is established to examine the heat transfer and melt pool behavior in PBF-LB/M. Surface tension, the Marangoni effect, and recoil pressure are implemented in the model, and evaporation-induced mass and thermal loss are fully considered in the computing element. The results show that the surface roughness and density of metal parts induced by heat transfer and melt pool behavior are closely related to process parameters such as laser power, layer thickness, scanning speed, etc. When the volumetric energy density is low, the insufficient fusion of metal particles leads to pore defects. When the line energy density is high, the melt track is smooth with low porosity, resulting in the high density of the products. Additionally, the partial melting of powder particles at the beginning and end of the melting track usually contributes to pore formation. These findings provide valuable insights for improving the quality and reliability of metal additive manufacturing. Full article

(This article belongs to the Special Issue Latest Developments in Advanced Machining Technologies for Materials)

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29 pages, 14256 KiB

Open AccessArticle

Bond Behavior and Critical Anchorage Length Prediction of Novel Negative Poisson’s Ratio Bars Embedded in Ultra-High-Performance Concrete

by Zhao Xu, Chang-Ze Xu, Xian-Liang Rong, Jun-Yan Wang and Xue-Yuan Ma

Materials 2025, 18(13), 3182; https://doi.org/10.3390/ma18133182 - 4 Jul 2025

Abstract

Negative Poisson’s ratio (NPR) reinforcement offers a novel solution to the usual trade-off between strength gains and ductility loss. Incorporating NPR into ultra-high-performance concrete (UHPC) effectively overcomes the ductility limitations of structural elements. However, the interfacial bonding between NPR reinforcement and UHPC is [...] Read more.

Negative Poisson’s ratio (NPR) reinforcement offers a novel solution to the usual trade-off between strength gains and ductility loss. Incorporating NPR into ultra-high-performance concrete (UHPC) effectively overcomes the ductility limitations of structural elements. However, the interfacial bonding between NPR reinforcement and UHPC is not sufficiently studied, especially its patterns and mechanisms, impeding the application of the materials. In this paper, the effects of nine design parameters (rebar type, prestrain, etc.) on the bond performance of NPR-UHPC through eccentric pull-out tests are investigated, and a quantitative discriminative indicator K_c for NPR-UHPC bond failure modes is established. The results showed that when K_c ≤ 4.3, 4.3 < K_c ≤ 5.64, and K_c ≥ 5.6, the NPR-UHPC specimens undergo splitting failure, splitting–pull-out failure, and pull-out failure, respectively. In terms of bonding with UHPC, the NPR bars outperform the HRB400 bars, and the HRB400 bars outperform the helical grooved (HG) bars. For the NPR bars, prestrain levels of 5.5%, 9.5%, and 22.0% decrease τ_u by 5.07%, 7.79%, and 17.01% and s_u by 7.00%, 15.88%, and 30.54%, respectively. Bond performance deteriorated with increasing rib spacing and decreasing rib height. Based on the test results, an artificial neural network (ANN) model is developed to accurately predict the critical embedded length l_cd and ultimate embedded length l_ud between NPR bars and UHPC. Moreover, the MAPE of the ANN model is only 53.9% of that of the regression model, while the RMSE is just 62.0%. Full article

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

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16 pages, 3080 KiB

Open AccessArticle

Durability Assessment of Alkali-Activated Geopolymers Matrices for Organic Liquid Waste Immobilization

by Rosa Lo Frano, Salvatore Angelo Cancemi, Eleonora Stefanelli and Viktor Dolin

Materials 2025, 18(13), 3181; https://doi.org/10.3390/ma18133181 - 4 Jul 2025

Abstract

This study investigates the mechanical and microstructural performance of three alkali-activated geopolymer formulations, constituted of metakaolin (MK), blast furnace slag (BFS), and a ternary blend of MK, BFS, and fly ash (MIX), for the immobilization of simulated radioactive liquid organic waste (RLOW). Thermal [...] Read more.

This study investigates the mechanical and microstructural performance of three alkali-activated geopolymer formulations, constituted of metakaolin (MK), blast furnace slag (BFS), and a ternary blend of MK, BFS, and fly ash (MIX), for the immobilization of simulated radioactive liquid organic waste (RLOW). Thermal ageing tests were performed to evaluate geopolymer durability, including fire exposure (800 °C) and climatic chamber cycles (from −20 to 40 °C). Characterization through thermogravimetric analysis (TGA), compression tests, and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) was carried out to assess material degradation after thermal ageing. Preliminary results showed substantial strength and microstructural degradation in oil-loaded specimens after cyclic climatic ageing, while fire-exposed blank matrices retained partial mechanical integrity. BFS matrices exhibited the best thermal resistance, attributable to the formation of Ca-Al-Si-hydrate (C-A-S-H) gels. These findings support the use of optimized geopolymer formulations for safe RLOW immobilization, while contributing to the advancement of knowledge on sustainable and regulatory-compliant direct conditioning technology. Full article

18 pages, 4309 KiB

Open AccessArticle

Optimizing the Thermal Treatment of Mining-Waste-Amended Clays for Ceramic Aggregates in Pavement Applications

by Murilo Miguel Narciso, Lisley Madeira Coelho, Sergio Neves Monteiro and Antônio Carlos Rodrigues Guimarães

Materials 2025, 18(13), 3180; https://doi.org/10.3390/ma18133180 - 4 Jul 2025

Abstract

Mining activities generate large volumes of tailings with significant environmental impact but also the potential for sustainable reuse in construction materials. This study evaluates the production of ceramic aggregates from mixtures of clay, sand, and iron ore waste subjected to thermal treatment at [...] Read more.

Mining activities generate large volumes of tailings with significant environmental impact but also the potential for sustainable reuse in construction materials. This study evaluates the production of ceramic aggregates from mixtures of clay, sand, and iron ore waste subjected to thermal treatment at temperatures ranging from 600 to 1100 °C. The influence of calcination temperature on mineralogical transformations and mechanical integrity was investigated using X-ray diffraction (XRD) and the

α

-Treton parameter, derived from standardized impact resistance testing. The results indicate that the formation of metakaolinite between 700 and 900 °C enhances mechanical resistance, while higher temperatures (>900 °C) lead to structural degradation, followed by partial recovery due to mullite crystallization. The

α

-Treton curve exhibited clear correlation with the phase changes identified by XRD, demonstrating its applicability as a low-cost, sensitive proxy for optimizing thermal activation. A simplified methodology is proposed to optimize the thermal activation of such materials by correlating firing temperature with mineralogical evolution and mechanical integrity, contributing to the development of sustainable ceramic aggregates for pavement applications. Full article

(This article belongs to the Special Issue Industrial Solid Wastes for Construction and Building Materials—Second Edition)

14 pages, 5562 KiB

Open AccessArticle

Microstructure and Mechanical Properties of AlCoCrFeNi High-Entropy Alloy-Reinforced Ti-6Al-4V Composites

by Abdulaziz Kurdi, Animesh Kumar Basak, Nachimuthu Radhika and Ahmed Degnah

Materials 2025, 18(13), 3179; https://doi.org/10.3390/ma18133179 - 4 Jul 2025

Abstract

High-entropy alloy (HEA) particle-reinforced metal matrix composites (MMCs) are a new generation of MMCs with potential applications as orthopedic material in automotive, aerospace, and biomedical fields. In this study, AlCoCrFeNi HEA-reinforced Ti-6Al-4V metal matrix composites (MMCs) were prepared by microwave sintering. The microstructural [...] Read more.

High-entropy alloy (HEA) particle-reinforced metal matrix composites (MMCs) are a new generation of MMCs with potential applications as orthopedic material in automotive, aerospace, and biomedical fields. In this study, AlCoCrFeNi HEA-reinforced Ti-6Al-4V metal matrix composites (MMCs) were prepared by microwave sintering. The microstructural aspects of the MMC were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), with an emphasis on the interdiffusion (ID) layer. The mechanical properties of the composites were studied by micro-pillar compression at the micro-length scale. The results show that the ID layer exists between the HEA particles and the matrix, is equiaxed in nature, and leads towards metallurgical bonding within the composite. The strength of this ID layer (1573 MPa of yield strength and 1867 MPa of compressive strength) and its Young’s modulus (570 MPa) were about 1.5 times lower than that of the matrix. The HEA particles exhibit the highest strength (2157 MPa of yield strength and 3356 MPa of compressive strength) and Young’s modulus (643 MPa), whereas the matrix falls in between 2372 MPa of yield strength and 2661 MPa of compressive strength, and a Young’s modulus of 721 MPa. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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23 pages, 2135 KiB

Open AccessArticle

Interaction Mechanisms in «Portland Cement—Functional Polymer Mineral Additives» Binder Produced by Different Methods

by Valeria Strokova, Svetlana Bondarenko, Irina Markova, Natalia Kozhukhova, Nikita Lukyanenko and Danil Potapov

Materials 2025, 18(13), 3178; https://doi.org/10.3390/ma18133178 - 4 Jul 2025

Abstract

The construction industry is the main consumer of mineral resources. At the same time, the Portland cement (PC) industry occupies a leading position, using expensive, high-quality raw materials. This is due to the high rate of construction in different areas (industrial, civil, road [...] Read more.

The construction industry is the main consumer of mineral resources. At the same time, the Portland cement (PC) industry occupies a leading position, using expensive, high-quality raw materials. This is due to the high rate of construction in different areas (industrial, civil, road construction, etc.). The widespread application of PC is due primarily to the strength and durability of composite materials based on it. Taking into account their specific purpose, PC-based composites are usually optimized to achieve specified characteristics and rational use of raw materials. To reduce PC consumption and justify the possibility of its use in complex binders, this manuscript analyzes the composition of a functional polymer–mineral additive; the nature and mechanisms of its interaction with PC depend on the method of introducing the additive (dry mixing/joint grinding of the clinker–gypsum mixture with the additive at the stage of binder preparation). Based on the data of XRD, IR, and SEM analysis, as well as taking into account patent information, the composition of the additive was clarified. The combined application of the above methods allowed us to establish the uniformity of the additive distribution in the binder depending on the introduction method and to evaluate the effect of each additive component and its mutual impact on the processes occurring during cement hydration. As a result, it was established that the most effective introduction method is combined grinding. A phenomenological model of the structure formation of additives containing cement paste is proposed. The binder production by the combined grinding method promotes the intensification of the processes occurring during hydration, as evidenced by the data of qualitative and quantitative XRD, IR, and DTA analysis, differential scanning calorimetry (DSC), and TGA analysis. Full article

(This article belongs to the Special Issue Advanced Polymers and Composites for Multifunctional Applications)

27 pages, 4726 KiB

Open AccessArticle

Prediction of Failure Pressure of Sulfur-Corrosion-Defective Pipelines Based on GABP Neural Networks

by Li Zhu, Yi Xia, Bin Jia and Jingyang Ma

Materials 2025, 18(13), 3177; https://doi.org/10.3390/ma18133177 - 4 Jul 2025

Abstract

This study systematically investigates the degradation and failure prediction of pipeline materials in sulfur-containing environments, with a particular focus on X52 pipeline steel exposed to high-sulfur environments. Through uniaxial tensile tests to assess mechanical properties, it was found that despite surface corrosion and [...] Read more.

This study systematically investigates the degradation and failure prediction of pipeline materials in sulfur-containing environments, with a particular focus on X52 pipeline steel exposed to high-sulfur environments. Through uniaxial tensile tests to assess mechanical properties, it was found that despite surface corrosion and a reduction in overall structural load-bearing capacity, the intrinsic mechanical properties of X52 steel did not exhibit significant degradation and remained within standard ranges. The Johnson–Cook constitutive model was developed to accurately capture the material’s plastic behavior. Subsequently, a genetic algorithm-optimized backpropagation (GABP) neural network was employed to predict the failure pressure of defective pipelines and the corrosion rate in acidic environments, with prediction errors controlled within 5%. By integrating the GABP model with NACE standard methods, a framework for predicting the remaining service life for in-service pipelines operating in sour environments was established. This method provides a novel and reliable approach for pipeline integrity assessment, demonstrating significantly higher accuracy than traditional empirical models and finite element analysis. Full article

(This article belongs to the Section Materials Simulation and Design)

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14 pages, 5135 KiB

Open AccessArticle

Effect of Cd Doping on the Gas-Sensitive Properties of ZnSn(OH)₆

by Yufeng Wen, Yanlin Yu, Huaizhang Gu, Guilian Wang and Fangqiang Yuan

Materials 2025, 18(13), 3176; https://doi.org/10.3390/ma18133176 - 4 Jul 2025

Abstract

The influence of Cd doping on the performance of ZnSn(OH)₆ (ZHS) as a gas sensor was systematically investigated through experimental and theoretical approaches. ZHS and Cd-doped ZHS samples were synthesized using the hydrothermal method. The microstructures of pure and Cd-doped ZHS were [...] Read more.

The influence of Cd doping on the performance of ZnSn(OH)₆ (ZHS) as a gas sensor was systematically investigated through experimental and theoretical approaches. ZHS and Cd-doped ZHS samples were synthesized using the hydrothermal method. The microstructures of pure and Cd-doped ZHS were characterized using various techniques. The results revealed that the pure ZHS sample exhibits good crystallinity and an octahedral morphology with particle sizes ranging from 800 to 1900 nm. After Cd doping, the particle size range was decreased to 700–1500 nm. A systematic investigation of the gas-sensing properties revealed that Cd-doped ZHS exhibits superior sensing performance toward ethanol gas compared to pure ZHS. Under operating conditions of 240 °C, 100 ppm concentration, and 30% relative humidity, the response of ZHS to ethanol gas exhibited a significantly higher value compared to other tested gases. After Cd doping, the response approximately doubled. Density functional theory calculations of electronic structures revealed that the enhanced ethanol sensing mechanism of Cd-doped ZHS is attributed to the narrowed band gap caused by Cd doping, which increases electron concentration and enhances

O^{-}

ion adsorption on the surface. Full article

(This article belongs to the Special Issue Materials for Photocatalytic and Electrocatalytic Applications)

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61 pages, 12222 KiB

Open AccessReview

Thin-Film Encapsulation for OLEDs and Its Advances: Toward Engineering

by Songju Li, Linfeng Lan, Min Li, Zhuo Gao, Xiaolin Yan, Dong Fu and Xianwen Sun

Materials 2025, 18(13), 3175; https://doi.org/10.3390/ma18133175 - 4 Jul 2025

Abstract

Thin-film encapsulation has been a critical method to realize small-size OLED displays. However, the manufacturing of large-size flexible OLED is still in the preparatory phase prior to commercialization, which entails more rigorous demands for reliability and flexibility with regard to thin-film encapsulation. This [...] Read more.

Thin-film encapsulation has been a critical method to realize small-size OLED displays. However, the manufacturing of large-size flexible OLED is still in the preparatory phase prior to commercialization, which entails more rigorous demands for reliability and flexibility with regard to thin-film encapsulation. This review, from the perspective of engineering for mass production, addresses the development of thin-film encapsulation and its three core properties for comprehensive validation while engineering, including basic properties, reliability, and compatibility. Moreover, considering the prospective evolution of display products, the review on novel thin-film encapsulation was conducted to evaluate the potential engineering value for thinning, ultra-flexibility, multifunctionality, novel equipment, and emerging technology. It is anticipated that some of the aforementioned technologies may prove to be of significant engineering value. It is therefore hoped that by comprehensive engineering verification, the commercial application of novel thin-film encapsulation can be promoted and the competitiveness of OLED products can be effectively enhanced. Full article

(This article belongs to the Special Issue New Techniques for Preparing Thin Films: Characteristics and Further Developments)

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15 pages, 2160 KiB

Open AccessArticle

Open-Pore Skeleton Prussian Blue as a Cathode Material to Achieve High-Performance Sodium Storage

by Wenxin Song, Yaxin Li, Jiahao Chen, Huihua Min, Xinyuan Wu, Xiaomin Liu and Hui Yang

Materials 2025, 18(13), 3174; https://doi.org/10.3390/ma18133174 - 4 Jul 2025

Abstract

Prussian blue and its analogs (PBAs), considered potential cathode materials for sodium-ion batteries (SIBs), still confront multiple challenges. For example, many defect vacancies and high crystal water content are generated during the fast crystallization of PBAs, impairing the rate performance. The stress accumulation [...] Read more.

Prussian blue and its analogs (PBAs), considered potential cathode materials for sodium-ion batteries (SIBs), still confront multiple challenges. For example, many defect vacancies and high crystal water content are generated during the fast crystallization of PBAs, impairing the rate performance. The stress accumulation during Na⁺ insertion/extraction destabilizes the lattice framework and then damages the electrochemical performance. Herein, iron-based Prussian blue with an open-pore skeleton structure (PB-3) is prepared using a facile template method which employs PVP and sodium citrate to control the crystallization rate and adjust the particle morphology. The prepared materials exhibit excellent kinetic properties and are conducive to mitigate the volume changes during ion insertion/extraction processes. PB-3 electrode not only exhibits a superior rate performance (92 mAh g⁻¹ reversible capacity at 2000 mA g⁻¹), but also presents superior cycling performance (capacity retention remained at 90.2% after 600 cycles at a current density of 500 mA g⁻¹). The highly reversible sodium ion insertion/extraction mechanism of PB-3 is investigated by ex situ XRD tests, which proves that the stabilized lattice structure can enhance the long cycling performance. In addition, the considerable capacitance contributes to the rate performance. This study provides valuable insights for the subsequent development of high-performance and stable cathodes for SIBs. Full article

(This article belongs to the Special Issue Development of Electrode Materials for Sodium Ion Batteries)

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19 pages, 3568 KiB

Open AccessArticle

Research on the Pavement Performance of Slag/Fly Ash-Based Geopolymer-Stabilized Soil

by Chenyang Yang, Yan Jiang, Zhiyun Li, Yibin Huang and Jinchao Yue

Materials 2025, 18(13), 3173; https://doi.org/10.3390/ma18133173 - 4 Jul 2025

Abstract

The road construction sector urgently requires environmentally friendly, low-carbon, and high-performance base materials. Traditional materials exhibit issues of high energy consumption and carbon emissions, making it difficult for them to align with sustainable development requirements. While slag- and fly ash-based geopolymers demonstrate promising [...] Read more.

The road construction sector urgently requires environmentally friendly, low-carbon, and high-performance base materials. Traditional materials exhibit issues of high energy consumption and carbon emissions, making it difficult for them to align with sustainable development requirements. While slag- and fly ash-based geopolymers demonstrate promising application potential in civil engineering, research on their application in road-stabilized soils remains insufficient. To address the high energy consumption and carbon emissions associated with conventional road base materials and to fill this research gap, this study investigated the utilization of industrial solid wastes through slag-based geopolymer and fly ash as stabilizers, systematically evaluating the pavement performance of two distinct soil types. Unconfined compressive strength tests and freeze–thaw cycling tests were conducted to elucidate the effects of stabilizer dosage, fly ash co-stabilization, and compaction degree on mechanical properties. The results demonstrated that the compressive strength of both stabilized soils increased significantly with higher slag-based geopolymer content, achieving peak values of 5.2 MPa (soil sample 1) and 4.5 MPa (soil sample 2), representing a 30% improvement over cement-stabilized soils with identical mix proportions. Fly ash co-stabilization exhibited more pronounced reinforcement effects on soil sample 2. At a 98% compaction degree, soil sample 1 maintained a stable 50% strength enhancement, whereas soil sample 2 displayed a dose-dependent exponential strength increase. Freeze–thaw resistance tests revealed the superior performance of soil sample 1, showing a loss of compressive strength (BDR) of 78% with 8% geopolymer stabilization alone, which improved to 90% after fly ash co-stabilization. For soil sample 2, the BDR increased from 64% to 80% through composite stabilization. This study confirms that slag/fly ash-based geopolymer-stabilized soils not only meet the strength requirements for heavy-traffic subbases and light-traffic base courses, but also demonstrates its great potential as a low-carbon and environmentally friendly material to replace traditional road base materials. Full article

(This article belongs to the Special Issue Modeling and Analysis of Composite Materials and Structures in Civil Engineering (Second Edition))

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12 pages, 3806 KiB

Open AccessArticle

Effects of Annealing Processes on Microstructure and Properties of FeNi-Based Amorphous Alloy

by Chenglong Sun, Mengen Shi, Xinyu Wang, Daying Deng and Weihuo Li

Materials 2025, 18(13), 3172; https://doi.org/10.3390/ma18133172 - 4 Jul 2025

Abstract

The present experiment is aimed at investigating the changes in the properties of an FeNiCBCo amorphous alloy after different stress relief annealing. It was established that, under equivalent temperature and time conditions, the strip that underwent no magnetic field annealing exhibited the maximum [...] Read more.

The present experiment is aimed at investigating the changes in the properties of an FeNiCBCo amorphous alloy after different stress relief annealing. It was established that, under equivalent temperature and time conditions, the strip that underwent no magnetic field annealing exhibited the maximum B_s of 1.09 T. The soft magnetic properties were found to be marginally enhanced by the transverse magnetic treatment, and the coercivity was notably reduced from 10.15 to 0.27 A/m after the longitudinal magnetic treatment. Furthermore, it was determined that, subsequent to the longitudinal magnetic treatment and the annealing treatment with no magnetic field, the strip exhibited enhanced mechanical properties due to the precipitation of the second phase A1 FeNi nanoparticles within the strip. In contrast, the transverse magnetic treatment significantly improved the strength of the alloy. Additionally, the strip demonstrated superior mechanical properties, while the strength of the alloys with the transverse magnetic treatment was significantly increased. This study demonstrates that transverse magnetic treatment can evidently enhance the strength, and magnetic field-free and longitudinal magnetic annealing treatments improve the soft magnetic properties, of amorphous alloys while maintaining good mechanical properties. Full article

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

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25 pages, 5042 KiB

Open AccessArticle

Surface Topography-Based Classification of Coefficient of Friction in Strip-Drawing Test Using Kohonen Self-Organising Maps

by Krzysztof Szwajka, Tomasz Trzepieciński, Marek Szewczyk, Joanna Zielińska-Szwajka and Ján Slota

Materials 2025, 18(13), 3171; https://doi.org/10.3390/ma18133171 - 4 Jul 2025

Abstract

One of the important parameters of the sheet metal forming process is the coefficient of friction (CoF). Therefore, monitoring the friction coefficient value is essential to ensure product quality, increase productivity, reduce environmental impact, and avoid product defects. Conventional CoF monitoring techniques pose [...] Read more.

One of the important parameters of the sheet metal forming process is the coefficient of friction (CoF). Therefore, monitoring the friction coefficient value is essential to ensure product quality, increase productivity, reduce environmental impact, and avoid product defects. Conventional CoF monitoring techniques pose a number of problems, including the difficulty in identifying the features of force signals that are sensitive to the variation in the coefficient of friction. To overcome these difficulties, this paper proposes a new approach to apply unsupervised artificial intelligence techniques with unbalanced data to classify the CoF of DP780 (HCT780X acc. to EN 10346:2015 standard) steel sheets in strip-drawing tests. During sheet metal forming (SMF), the CoF changes owing to the evolution of the contact conditions at the tool–sheet metal interface. The surface topography, the contact loads, and the material behaviour affect the phenomena in the contact zone. Therefore, classification is required to identify possible disturbances in the friction process causing the change in the CoF, based on the analysis of the friction process parameters and the change in the sheet metal’s surface roughness. The Kohonen self-organising map (SOM) was created based on the surface topography parameters collected and used for CoF classification. The CoF determinations were performed in the strip-drawing test under different lubrication conditions, contact pressures, and sliding speeds. The results showed that it is possible to classify the CoF using an SOM for unbalanced data, using only the surface roughness parameter Sq and selected friction test parameters, with a classification accuracy of up to 98%. Full article

(This article belongs to the Section Metals and Alloys)

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