Materials

15 pages, 9263 KiB

Open AccessArticle

Corrosion Behavior of 700L Automotive Beam Steel in Marine Atmospheric Environment

by Younian He, Yuwei Liu, Chuan Wang, Gongwang Cao, Chunlin He and Zhenyao Wang

Materials 2024, 17(20), 4964; https://doi.org/10.3390/ma17204964 (registering DOI) - 11 Oct 2024

The marine atmospheric corrosion behavior of 700L high-strength automotive beam steel exposed for 36 months was investigated by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and electrochemical technology. The corrosion kinetics of 700L steel followed the exponential function: D = 4.85t [...] Read more.

The marine atmospheric corrosion behavior of 700L high-strength automotive beam steel exposed for 36 months was investigated by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and electrochemical technology. The corrosion kinetics of 700L steel followed the exponential function: D = 4.85t^1.23. The rust layers were mainly composited of γ-FeOOH, α-FeOOH, γ-Fe₂O₃, and Fe₃O₄, regardless of the exposure duration. With an extended exposure time, the porosity, cracking, and spalling of the rust layers increased, and the densification and thickness uniformity decreased. Electrochemical measurements displayed that the corrosion resistance of the rusted 700L steel gradually decreased with increasing exposure time. A good correlation was found between rust layer composition, microstructure, and corrosion resistance. Full article

(This article belongs to the Special Issue Corrosion of Materials: Evaluation, Testing, Protection, and Failure Analysis (2nd Edition))

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14 pages, 1664 KiB

Open AccessArticle

Flexible Highly Thermally Conductive PCM Film Prepared by Centrifugal Electrospinning for Wearable Thermal Management

by Jiaxin Qiao, Chonglin He, Zijiao Guo, Fankai Lin, Mingyong Liu, Xianjie Liu, Yifei Liu, Zhaohui Huang, Ruiyu Mi and Xin Min

Materials 2024, 17(20), 4963; https://doi.org/10.3390/ma17204963 (registering DOI) - 11 Oct 2024

Abstract

Personal thermal management materials integrated with phase-change materials have significant potential to satisfy human thermal comfort needs and save energy through the efficient storage and utilization of thermal energy. However, conventional organic phase-change materials in a solid state suffer from rigidity, low thermal [...] Read more.

Personal thermal management materials integrated with phase-change materials have significant potential to satisfy human thermal comfort needs and save energy through the efficient storage and utilization of thermal energy. However, conventional organic phase-change materials in a solid state suffer from rigidity, low thermal conductivity, and leakage, making their application challenging. In this work, polyethylene glycol (PEG) was chosen as the phase-change material to provide the energy storage density, polyethylene oxide (PEO) was chosen to provide the backbone structure of the three-dimensional polymer network and cross-linked with the PEG to provide flexibility, and carbon nanotubes (CNTs) were used to improve the mechanical and thermal conductivity of the material. The thermal conductivity of the composite fiber membranes was boosted by 77.1% when CNTs were added at 4 wt%. Water-resistant modification of the composite fiber membranes was successfully performed using glutaraldehyde-saturated steam. The resulting composite fiber membranes had a reasonable range of phase transition temperatures, and the CC₄PCF-55 membranes had melting and freezing latent heats of 66.71 J/g and 64.74 J/g, respectively. The results of this study prove that the green CC₄PCF-55 composite fiber membranes have excellent flexibility, with good thermal energy storage capacity and thermal conductivity and, therefore, high potential in the field of flexible wearable thermal management textiles. Full article

(This article belongs to the Special Issue Feature Papers in Refractories and Ceramics: Microstructure, Properties and Applications, Volume II)

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13 pages, 9534 KiB

Open AccessArticle

Mechanical and Tribological Properties of Laminated (NbTaMoW)N_x Films

by Yan-Zhi Liao and Yung-I Chen

Materials 2024, 17(20), 4962; https://doi.org/10.3390/ma17204962 (registering DOI) - 11 Oct 2024

Abstract

Laminated (NbTaMoW)N_x films were prepared via co-sputtering. The sputtering variables were a substrate holder rotation speed of 2 and 10 rpm and a nitrogen flow ratio (f_N2 = N₂/(Ar + N₂)) of 0.1, 0.2, and 0.4. [...] Read more.

Laminated (NbTaMoW)N_x films were prepared via co-sputtering. The sputtering variables were a substrate holder rotation speed of 2 and 10 rpm and a nitrogen flow ratio (f_N2 = N₂/(Ar + N₂)) of 0.1, 0.2, and 0.4. The (NbTaMoW)N_x films fabricated at 30 rpm displayed columnar structures. The phase structures of the laminated (NbTaMoW)N_x films varied from multiple body-centered cubic phases to a nanocrystalline and a face-centered cubic phase as the f_N2 increased from 0.1 to 0.2 and 0.4. The mechanical and tribological properties of the laminated (NbTaMoW)N_x films were evaluated. The laminated (NbTaMoW)N_x films deposited at an f_N2 of 0.4 had hardnesses of 25.2 and 26.1 GPa when prepared at 2 and 10 rpm, respectively, lower than the value of 29.9 GPa for the columnar (NbTaMoW)N_x film prepared at an f_N2 of 0.4 and 30 rpm. In contrast, the wear resistances of the laminated (NbTaMoW)N_x films were superior to those of the columnar (NbTaMoW)N_x films. Full article

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21 pages, 9188 KiB

Open AccessArticle

Separation of Macro- and Micro-Texture to Characterize Skid Resistance of Asphalt Pavement

by Tao Xie, Enhui Yang, Qiang Chen, Junying Rao, Haopeng Zhang and Yanjun Qiu

Materials 2024, 17(20), 4961; https://doi.org/10.3390/ma17204961 (registering DOI) - 11 Oct 2024

Abstract

The skid resistance of asphalt pavement is an important factor affecting road safety. However, few studies have characterized the contribution of the macro- and micro-texture to the skid resistance of asphalt pavement. In this paper, the generalized extreme studentized deviate (GESD) and neighboring-region [...] Read more.

The skid resistance of asphalt pavement is an important factor affecting road safety. However, few studies have characterized the contribution of the macro- and micro-texture to the skid resistance of asphalt pavement. In this paper, the generalized extreme studentized deviate (GESD) and neighboring-region interpolation algorithm (NRIA) were used to identify and replace outliers, and median filters were used to suppress noise in texture data to reconstruct textures. On this basis, the separation of the macro- and micro-texture and the Monte Carlo algorithm were used to characterize the skid resistance of asphalt pavement. The results show that the GESD method can accurately identify outliers in the texture, and the median filtering can eliminate burrs in texture data while retaining more original detail information. The contribution of the macro-texture on the skid resistance is mainly attributed to the frictional resistance caused by the adhesion and elastic hysteresis, and the main contribution of the micro-texture is a micro-bulge cutting part in the friction mechanism. This investigation can provide inspiration for the interior mechanism and the specific relationship between the pavement textures and the skid resistance of asphalt pavement. Full article

(This article belongs to the Special Issue Mechanical Property Research of Advanced Asphalt-Based Materials)

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11 pages, 10750 KiB

Open AccessArticle

Effect of Tempering Temperature on the Aqueous Corrosion Resistance of 9Cr Series Heat-Resistant Steel

by Hui Li and Hao Bai

Materials 2024, 17(20), 4960; https://doi.org/10.3390/ma17204960 (registering DOI) - 11 Oct 2024

Abstract

In this investigation, the aqueous corrosion resistance of 9Cr series heat-resistant steel during tempering was investigated. Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectrometer (EDS) were used to analyze the effect of tempering temperature on the microstructure and precipitation behavior [...] Read more.

In this investigation, the aqueous corrosion resistance of 9Cr series heat-resistant steel during tempering was investigated. Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectrometer (EDS) were used to analyze the effect of tempering temperature on the microstructure and precipitation behavior of precipitates. The heat-resisting steel was heated to 1150 °C for 1 h, and then tempered at different temperatures between 680 °C and 760 °C for 2 h. The microstructure of the heat-resistant steel after tempering was composed of lath-tempered martensite and fine precipitates. The hardness decreased with increasing tempering temperature, ranging from HBW 261 to HBW 193. The aqueous corrosion resistance improved as the tempering temperatures increased from 680 °C to 720 °C but deteriorated at higher temperatures, such as 760 °C, which was obtained by an electrochemical corrosion performance test. The aqueous corrosion resistance was affected by the decrease in dislocation density and the decrease in Cr solution in the tempered martensite. With the increase in the tempering temperature, the aqueous corrosion potential first increases and then decreases, the self-corrosion current density first decreases and then increases, and the polarization resistance first increases and then decreases. Furthermore, the increase in corrosion resistance is attributed to the reduction in dislocation density and chromium depletion in the martensitic structure as the tempering temperature approaches 720 °C. This paper reveals the effect of tempering temperature on the corrosion resistance of 9Cr series heat-resistant steel, which is a further exploration of a known phenomenon. Full article

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14 pages, 3431 KiB

Open AccessArticle

Concanavalin a Grafted Nanoemulsions for Nasal Delivery: Preliminary Studies with Fluorescently Labelled Formulations

by Merve Mışraklı, Sebastiano Antonio Rizzo, Valentina Bordano, Annalisa Bozza, Luca Ferraris, Elisabetta Marini, Elisabetta Muntoni, Maria Teresa Capucchio, Anna Scomparin and Luigi Battaglia

Materials 2024, 17(20), 4959; https://doi.org/10.3390/ma17204959 (registering DOI) - 11 Oct 2024

Abstract

Nasal delivery is a non-invasive strategy for effective drug delivery. Nevertheless, in order to promote drug uptake by the nasal mucosa, it is fundamental to increase its residence time in the administration site. To this aim, nano-sized drug delivery systems are widely exploited. [...] Read more.

Nasal delivery is a non-invasive strategy for effective drug delivery. Nevertheless, in order to promote drug uptake by the nasal mucosa, it is fundamental to increase its residence time in the administration site. To this aim, nano-sized drug delivery systems are widely exploited. Within this context, the commercially available nanoemulsion for parenteral nutrition is a biocompatible, safe and clinically approved vehicle for drug delivery. Furthermore, the nanodroplet surface can be modified via a well-established protocol to graft Concavalin A, a lectin capable of improving the mucosal adhesion, by binding to the α-mannose and α-glucose residues of the mucosal glycocalyx. The obtained targeted formulation is able to induce haemagglutination, as opposite to non-modified nanoemulsion. Furthermore, the ConA grafting maintains the physicochemical properties of the nanodroplets (size~230 nm, Z < −35 mV) and does not interfere with the loading of the Rose Bengal fluorescent probe. Fluorescently labelled ConA grafted nanodroplets showed enhanced permeation and accumulation in ex vivo bovine nasal mucosa. This study is a proof of concept that Concanavalin A can be used to decorate the surface of nanodroplets, acting as a permeation promoter. Full article

(This article belongs to the Section Biomaterials)

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19 pages, 7065 KiB

Open AccessArticle

Bending Performance of Reinforced Concrete Beams with Rubber as Form of Fiber from Waste Tires

by Ali Serdar Ecemiş, Emrah Madenci, Memduh Karalar, Sabry Fayed, Essam Althaqafi and Yasin Onuralp Özkılıç

Materials 2024, 17(20), 4958; https://doi.org/10.3390/ma17204958 (registering DOI) - 11 Oct 2024

Abstract

An investigation was conducted to assess the efficacy of using waste rubber as a substitute for a portion of an aggregate to enhance concrete’s sustainability. For the purpose of accomplishing this objective, a total of 12 specimens were constructed and then subjected to [...] Read more.

An investigation was conducted to assess the efficacy of using waste rubber as a substitute for a portion of an aggregate to enhance concrete’s sustainability. For the purpose of accomplishing this objective, a total of 12 specimens were constructed and then subjected to a series of tests to investigate their bending behavior. The samples were constructed with the following dimensions: 1000 mm length and a 100 mm by 150 mm cross-sectional area. A few factors were selected, including the impacts of the longitudinal reinforcement ratio and the waste rubber ratio. Based on the volume of aggregates, rubber replacement rates of 0%, 5%, 10%, and 15% were investigated in this study. To assess the beam bending behavior, the stirrup width and spacing were kept constant at ∅6/10. The longitudinal reinforcement was composed of three diameters: ∅6 at the top (for all beams) and ∅8, ∅10, and ∅12 at the bottom. The experimental results demonstrated that the effects of varying amounts of waste rubber and tension reinforcement on the bending and cracking of reinforced concrete beams (RCBs) were varied. The findings indicate that the incorporation of waste rubber into concrete results in a reduction in both the load-carrying capacity and the level of deformation of the material. Additionally, it was shown that as the amount of waste rubber in the RCB increased, the energy absorption capacity and ultimate load decreased. There was a reduction in energy dissipation of 53.71%, 51.69%, and 40.55% for ∅8 when longitudinal reinforcement was applied at 5%, 10%, and 15% replacement, respectively. Additionally, there were reductions of 25.35%, 9.31%, and 58.15% for ∅10, and 38.69%, 57.79%, and 62.44% for ∅12, respectively. Full article

(This article belongs to the Special Issue Advance in Sustainable Construction and Building Materials (2nd Edition))

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14 pages, 3436 KiB

Open AccessArticle

Advancing Sustainability: Geraniol-Enhanced Waterborne Acrylic Pressure-Sensitive Adhesives without Chemical Modification

by Ludovica Di Lorenzo, Simone Bordignon, Michele R. Chierotti, Ignazio Andrea Alfeo, Adrian Krzysztof Antosik and Valentina Brunella

Materials 2024, 17(20), 4957; https://doi.org/10.3390/ma17204957 - 10 Oct 2024

Abstract

The escalating global emphasis on sustainability, coupled with stringent regulatory frameworks, has spurred the quest for environmentally viable alternatives to petroleum-derived materials. Within this context, the adhesives industry has been actively seeking renewable options and eco-friendly synthesis pathways. This study introduces geraniol, a [...] Read more.

The escalating global emphasis on sustainability, coupled with stringent regulatory frameworks, has spurred the quest for environmentally viable alternatives to petroleum-derived materials. Within this context, the adhesives industry has been actively seeking renewable options and eco-friendly synthesis pathways. This study introduces geraniol, a monoterpenoid alcohol, in its unmodified form, as a key component in the production of waterborne pressure-sensitive adhesives (PSAs) based on acrylic latex through emulsion polymerization. Multiple formulations were developed at varying reaction times. The adhesives underwent comprehensive chemical characterization employing techniques such as Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Nuclear Magnetic Resonance (NMR), Gel Permeation Chromatography (GPC), and dynamic light scattering (DLS). The viscosities of the formulations were measured between 4000 and 5000 cP. Adhesion tests showed peel strength values of 0.52 N/mm on cardboard and 0.32 N/mm on painted steel for the geraniol-based formulations. The results demonstrate the potential for geraniol-based PSAs to offer a sustainable alternative to petroleum-derived adhesives, with promising thermal and adhesive properties. Full article

(This article belongs to the Section Polymeric Materials)

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12 pages, 5108 KiB

Open AccessArticle

Prediction of Mechanical Properties of Rare-Earth Magnesium Alloys Based on Convolutional Neural Networks

by Mei Cheng, Xiya Jia and Zhimin Zhang

Materials 2024, 17(20), 4956; https://doi.org/10.3390/ma17204956 - 10 Oct 2024

Abstract

Rare-earth magnesium alloys exhibit higher comprehensive mechanical properties compared to other series of magnesium alloys, effectively expanding their applications in aerospace, weapons, and other fields. In this work, the tensile strength, yield strength, and elongation of a Mg-Gd-Y-Zn-Zr rare-earth magnesium alloy under different [...] Read more.

Rare-earth magnesium alloys exhibit higher comprehensive mechanical properties compared to other series of magnesium alloys, effectively expanding their applications in aerospace, weapons, and other fields. In this work, the tensile strength, yield strength, and elongation of a Mg-Gd-Y-Zn-Zr rare-earth magnesium alloy under different process conditions were determined, and a large number of microstructure observations and analyses were carried out for the tensile specimens; a prediction model of the corresponding mechanical properties was established by using a convolutional neural network (CNN), in which the metallographic diagram of the rare-earth magnesium alloy was taken as the input, and the corresponding tensile strength, yield strength, elongation, and three mechanical properties were taken as the output. The stochastic gradient descent (SGD) algorithm was used for parameter optimization and experimental validation, and the results showed that the average relative errors of the tensile strength and yield strength prediction results were 1.90% and 3.14%, respectively, which were smaller than the expected error of 5%. Full article

(This article belongs to the Section Mechanics of Materials)

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10 pages, 909 KiB

Open AccessArticle

Strong Impact of Particle Size Polydispersity on the Thermal Conductivity of Yukawa Crystals

by Konstantin V. Tretiakov and Krzysztof Hyżorek

Materials 2024, 17(20), 4955; https://doi.org/10.3390/ma17204955 - 10 Oct 2024

Abstract

Control of thermal transport in colloidal crystals plays an important role in modern technologies. A deeper understanding of the governing heat transport processes in various systems, such as polydisperse colloidal crystals, is required. This study shows how strongly the particle size polydispersity of [...] Read more.

Control of thermal transport in colloidal crystals plays an important role in modern technologies. A deeper understanding of the governing heat transport processes in various systems, such as polydisperse colloidal crystals, is required. This study shows how strongly the particle size polydispersity of a model colloidal crystal influences the thermal conductivity. The thermal conductivity of model colloidal crystals has been calculated using molecular dynamics simulations. The model crystals created by particles interacting through Yukawa (screened-Coulomb) interaction are assumed to have a face-centered cubic structure. The influence of the Debye screening length, contact potential, and particle size polydispersity on the thermal conductivity of Yukawa crystals was investigated. It was found that an increase in particle size polydispersity causes a strong—almost fivefold—decrease in the thermal conductivity of Yukawa crystals. In addition, the obtained results showed that the effect of the particle size polydispersity on reducing the thermal conductivity of Yukawa crystals is stronger than changes in values of the Debye screening length or the contact potential. Full article

(This article belongs to the Special Issue Liquid Crystals and Other Partially Disordered Molecular Systems)

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14 pages, 7494 KiB

Open AccessArticle

Effect of Eu Ions Concentration in Y₂O₃-Based Transparent Ceramics on the Electron Irradiation Induced Luminescence and Damage

by Wenhui Lou, Yang Tang, Haohong Chen, Yisong Lei, Hui Lin, Ruijin Hong, Zhaoxia Han and Dawei Zhang

Materials 2024, 17(20), 4954; https://doi.org/10.3390/ma17204954 - 10 Oct 2024

Abstract

Eu³⁺-doped Y2O3-based luminescent materials can be used as a scintillator for electron or high energy β-ray irradiation, which are essential for applications such as electron microscopy and nuclear batteries. Therefore, it is essential to understand their defect mechanisms and to develop [...] Read more.

Eu³⁺-doped Y2O3-based luminescent materials can be used as a scintillator for electron or high energy β-ray irradiation, which are essential for applications such as electron microscopy and nuclear batteries. Therefore, it is essential to understand their defect mechanisms and to develop materials with excellent properties. In this paper, Y2O3-based transparent ceramics with different Eu³⁺ doping concentrations were prepared by solid-state reactive vacuum sintering. This series of transparent ceramic samples exhibits strong red emission under electron beam excitation at the keV level. However, color change appears after the high-energy electron irradiation due to the capture of electrons by the traps in the Y₂O₃ lattice. Optical transmittance, laser-excited luminescence, X-ray photoelectron spectroscopy (XPS), and other analyses indicated that the traps, or the color change, mainly originate from the residual oxygen vacancies, which can be suppressed by high Eu doping. Seen from the cathodoluminescence (CL) spectra, higher doping concentrations of Eu³⁺ showed stronger resistance to electron irradiation damage, but also resulted in lower emissions due to concentration quenching. Therefore, 10% doping of Eu was selected in this work to keep the high emission intensity and strong radiation resistance both. This work helps to enhance the understanding of defect formation mechanisms in the Y₂O₃ matrix and will be of benefit for the modification of scintillation properties for functional materials systems. Full article

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

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11 pages, 2254 KiB

Open AccessArticle

The Impact of Substrate Temperature on the Adhesion Strength of Electroplated Copper on an Al-Doped ZnO/Si System

by Jiun-Yi Tseng, Wen-Jauh Chen and Ping-Hang Chen

Materials 2024, 17(20), 4953; https://doi.org/10.3390/ma17204953 - 10 Oct 2024

Abstract

This research, which involved a comprehensive methodology, including depositing electroplated copper on a copper seed layer and Al-doped ZnO (AZO) thin films on textured silicon substrates using DC magnetron sputtering with varying substrate heating, has yielded significant findings. The study thoroughly investigated the [...] Read more.

This research, which involved a comprehensive methodology, including depositing electroplated copper on a copper seed layer and Al-doped ZnO (AZO) thin films on textured silicon substrates using DC magnetron sputtering with varying substrate heating, has yielded significant findings. The study thoroughly investigated the effects of substrate temperature (Ts) on copper adhesion strength and morphology using the peel force test and electron microscopy. The peel force test was conducted at angles of 90°, 135°, and 180°. The average adhesion strength was about 0.2 N/mm for the samples without substrate heating. For the samples with substrate heating at 100 °C, the average peeling force of the electroplated copper film was about 1 N/mm. The average peeling force increased to 1.5 N/mm as the substrate heating temperature increased to 200 °C. The surface roughness increases as the annealing temperature of the Cu/AZO/Si sample increases. These findings not only provide a reliable and robust method for applying AZO transparent conductive films onto silicon solar cells but also underscore its potential to significantly enhance the efficiency and durability of solar cells significantly, thereby instilling confidence in the field of solar cell technology. Full article

(This article belongs to the Section Energy Materials)

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17 pages, 5545 KiB

Open AccessArticle

Effects of Samarium Doping on the Dielectric Properties of BaBi₂Nb₂O₉ Aurivillius Ceramics

by Michał Rerak, Jolanta Makowska, Tomasz Goryczka, Beata Wodecka-Duś, Katarzyna Osińska, Grzegorz Tytko and Małgorzata Adamczyk-Habrajska

Materials 2024, 17(20), 4952; https://doi.org/10.3390/ma17204952 - 10 Oct 2024

Abstract

This study investigates the influence of samarium (Sm³⁺) doping on the structural, microstructural, mechanical, and dielectric properties of BaBi₂Nb₂O₉ (BBN) ceramics. Using the solid-state reaction method, samples of BaBi_2-xSm_xNb₂O₉ [...] Read more.

This study investigates the influence of samarium (Sm³⁺) doping on the structural, microstructural, mechanical, and dielectric properties of BaBi₂Nb₂O₉ (BBN) ceramics. Using the solid-state reaction method, samples of BaBi_2-xSm_xNb₂O₉ with varying concentrations of Sm (x = 0.01; 0.02; 0.04; 0.06; 0.08; 0.1) were prepared. Thermal analysis, microstructure characterization via SEM and EDS, X-ray diffraction, mechanical testing, and dielectric measurements were conducted. The results revealed that increasing Sm³⁺ concentration led to the formation of single-phase materials with a tetragonal structure at room temperature. Mechanical properties, such as Young’s modulus and stiffness, improved with Sm doping, indicating stronger atomic bonding. Dielectric properties showed that low concentrations of Sm³⁺ slightly increased electrical permittivity, while higher concentrations reduced it. The presence of Sm³⁺ also affected the relaxor properties, evidenced by changes in the freezing temperature and activation energy. Overall, the study concludes that samarium doping enhances the structural and functional properties of BBN ceramics, making them promising candidates for high-temperature piezoelectric and dielectric applications. The findings provide valuable insights into tailoring ceramic materials for advanced technological applications. Full article

(This article belongs to the Special Issue Properties of Ceramic Composites)

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16 pages, 2131 KiB

Open AccessArticle

The Effects of Ester and Ether Polycarboxylate Superplasticizers on the Fluidity and Setting Behavior of Alkali-Activated Slag Paste

by Yong Jic Kim, Sung Choi and Sung Rok Oh

Materials 2024, 17(20), 4951; https://doi.org/10.3390/ma17204951 - 10 Oct 2024

Abstract

This study aims to investigate the comparative performance of ester- and ether-based polycarboxylate superplasticizers in maintaining the fluidity and controlling the setting time of alkali-activated slag (AAS) paste. The experiments employed rheological tests, mini-slump tests, ultrasonic pulse velocity (UPV) measurements, and gel permeation [...] Read more.

This study aims to investigate the comparative performance of ester- and ether-based polycarboxylate superplasticizers in maintaining the fluidity and controlling the setting time of alkali-activated slag (AAS) paste. The experiments employed rheological tests, mini-slump tests, ultrasonic pulse velocity (UPV) measurements, and gel permeation chromatography (GPC) analysis. The results indicate that ether-based superplasticizers maintain fluidity approximately 25% longer than their ester-based counterparts and extend the setting time by about 30%. The enhanced performance of ether-based superplasticizers is attributed to their superior molecular stability in highly alkaline environments, which mitigates early polymer degradation. Additionally, the Na₂O/SiO₂ ratio was maintained at 1:1 throughout the experiments to ensure consistency in the activation process. The relationship between fluidity loss and the onset of setting occurs more rapidly in AAS paste than in conventional cement-based systems. These findings provide valuable insights for the development of environmentally friendly construction materials by optimizing the use of superplasticizers in alkali-activated systems. Full article

(This article belongs to the Special Issue New Findings in Cementitious Materials (2nd Edition))

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27 pages, 25873 KiB

Open AccessArticle

Biomimetic Modular Honeycomb with Enhanced Crushing Strength and Flexible Customizability

by Lumin Shen, Yuanzhi Wu, Tuo Ye, Tianyu Gao, Shanmei Zheng, Zhihao Long, Xi Ren, Huangyou Zhang, Junwen Huang and Kai Liu

Materials 2024, 17(20), 4950; https://doi.org/10.3390/ma17204950 - 10 Oct 2024

Abstract

The integration of biomimetic principles into the sophisticated design of honeycomb structures has gained significant traction. Inspired by the natural reinforcement mechanisms observed in tree stems, this research introduces localized thickening to the conventional honeycombs, leading to the development of variable-density honeycomb blocks. [...] Read more.

The integration of biomimetic principles into the sophisticated design of honeycomb structures has gained significant traction. Inspired by the natural reinforcement mechanisms observed in tree stems, this research introduces localized thickening to the conventional honeycombs, leading to the development of variable-density honeycomb blocks. These blocks are strategically configured to form modular honeycombs. Initially, the methodology for calculating the relative density of the new design is meticulously detailed. Following this, a numerical model based on the plastic limit theorem, verified experimentally, is used to investigate the in-plane deformation models of modular honeycomb under the low- and high-velocity impact and to establish a theoretical framework for compressive strength. The results confirm that the theoretical predictions for crushing strength in the modular honeycomb align closely with numerical findings across both low- and high-velocity impacts. Further investigation into densification strain, energy absorption, and gradient strategy is conducted using both simulation and experimental approaches. The outcomes indicate that the innovative design outperforms conventional honeycombs by significantly enhancing the crushing strength under low-velocity impacts through the judicious arrangement of honeycomb blocks. Additionally, with a negligible difference in densification strains, the modular honeycomb demonstrates superior energy dissipation capabilities compared to its conventional counterparts. At a strain of 0.85, the modular honeycomb’s energy absorption capacity improves by 36.68% at 1 m/s and 25.47% at 10 m/s compared to the conventional honeycomb. By meticulously engineering the arrangement of sub-honeycombs, it is possible to develop a modular honeycomb that exhibits a multi-plateau stress response under uniaxial and biaxial compression. These advancements are particularly beneficial to the development of auto crash absorption systems, high-end product transportation packaging, and personalized protective gear. Full article

(This article belongs to the Section Biomaterials)

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23 pages, 28085 KiB

Open AccessArticle

The Influence of Temperature in the Wire Drawing Process on the Wear of Drawing Dies

by Maciej Suliga, Piotr Szota, Monika Gwoździk, Joanna Kulasa and Anna Brudny

Materials 2024, 17(20), 4949; https://doi.org/10.3390/ma17204949 - 10 Oct 2024

Abstract

This paper presents a wear analysis of tungsten carbide drawing dies in the process of steel wire drawing. The finite element method (FEM) analysis showed a significant correlation between drawing die geometry, single reduction size and drawing speed on the rate of drawing [...] Read more.

This paper presents a wear analysis of tungsten carbide drawing dies in the process of steel wire drawing. The finite element method (FEM) analysis showed a significant correlation between drawing die geometry, single reduction size and drawing speed on the rate of drawing die wear. It has been shown that in steel wire drawing at higher drawing speeds, intense heating of the drawing die occurs due to friction at the wire/drawing die interface, leading to premature wear. Tribological tests on the material for the drawing die cores (94%WC+6%Co) confirmed the gradual abrasion of the steel and carbide sample surfaces with the “products” of abrasion sticking to their surfaces. The increase in temperature increases the coefficient of friction, translating into accelerated wear of the drawing dies. Full article

(This article belongs to the Special Issue Metalworking Processes: Theoretical and Experimental Study)

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23 pages, 3251 KiB

Open AccessArticle

Regeneration and Single Stage Batch Adsorber Design for Efficient Basic Blue-41 Dye Removal by Porous Clay Heterostructures Prepared from Al13 Montmorillonite and Pillared Derivatives

by Saheed A. Popoola, Hmoud Al Dmour, Rawan Al-Faze, Mohd Gulfam Alam, Souad Rakass, Hicham Oudghiri Hassani and Fethi Kooli

Materials 2024, 17(20), 4948; https://doi.org/10.3390/ma17204948 - 10 Oct 2024

Abstract

Porous clay heterostructures are a hybrid precursor between the pillaring process and organoclays. In this study, the organoclay was substituted by an aluminium intercalated species clay or pillared alumina clays. A porous clay heterostructure was successfully achieved from an aluminium intercalated species clay, [...] Read more.

Porous clay heterostructures are a hybrid precursor between the pillaring process and organoclays. In this study, the organoclay was substituted by an aluminium intercalated species clay or pillared alumina clays. A porous clay heterostructure was successfully achieved from an aluminium intercalated species clay, due to the easy exchange of the aluminium species by the cosurfactant and silica species. However, using alumina pillared clays, the porous clay heterostructures were not formed; the alumina species were strongly attached to clay sheets which made difficult their exchange with cosurfactant molecules. In this case, the silica species were polymerized and decorated the surface of the used materials as indicated by different characterization techniques. The specific surface area of the porous clay heterostructure material reached 880 m²/g, and total pore volume of 0.258 cc/g, while the decorated silica alumina pillared clays exhibited lower specific surface area values of 244–440 m²/g and total pore volume of 0.315 to 0.157 cc/g. The potential of the synthesized materials was evaluated as a basic blue-41 dye removal agent. Porous clay heterostructure material has a removal capacity of 279 mg/g; while the other materials exhibited lower removal capacities between 75 mg/g and 165 mg/g. The used regeneration method was related to the acidity of the studied materials. The acidity of the materials possessed an impact on the adopted regeneration procedure in this study, the removal efficiency was maintained at 80% of the original performance after three successive regeneration cycles for the porous clay heterostructure. The Langmuir isotherm characteristics were used to propose a single-stage batch design. Porous clay heterostructures with a higher removal capacity resulted in a decrease in the quantities needed to achieve the target removal percentage of the BB-41 dye from an aqueous solution. Full article

(This article belongs to the Special Issue Recent Advances in the Environmental Remediation Using Zeolites and Other Adsorbent Materials)

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11 pages, 2359 KiB

Open AccessArticle

An Investigation of Oxides of Tantalum Produced by Pulsed Laser Ablation and Continuous Wave Laser Heating

by Alexander W. Auner, Jonathan C. Crowhurst, David G. Weisz, Zurong Dai and Kimberly B. Knight

Materials 2024, 17(20), 4947; https://doi.org/10.3390/ma17204947 - 10 Oct 2024

Abstract

Recent progress has seen multiple Ta₂O₅ polymorphs generated by different synthesis techniques. However, discrepancies arise when these polymorphs are produced in widely varying thermodynamic conditions and characterized using different techniques. This work aimed to characterize and compare Ta₂O [...] Read more.

Recent progress has seen multiple Ta₂O₅ polymorphs generated by different synthesis techniques. However, discrepancies arise when these polymorphs are produced in widely varying thermodynamic conditions and characterized using different techniques. This work aimed to characterize and compare Ta₂O₅ particles formed at high and low temperatures using nanosecond pulsed laser ablation (PLA) and continuous wave (CW) laser heating of a local area of tantalum in either air or an ¹⁸O₂ atmosphere. Scanning electron microscopy (SEM) and Raman spectroscopy of the micrometer-sized particles generated by PLA were consistent with either a localized amorphous Ta₂O₅ phase or a similar, but not identical, crystalline β-Ta₂O₅ phase. The Raman spectrum of the material formed at the point of CW laser impingement was in good agreement with the previously established ceramic “H-Ta₂O₅” phase. TEM and electron diffraction analysis of these particles indicated the phase structure matched an oxygen-vacated superstructure of monoclinic H-Ta₂O₅. Further from the point of laser impingement, CW heating produced particles with a Raman spectrum that matched β-Ta₂O₅. We confirmed that the high-temperature ceramic phase characterized in previous work by Raman spectroscopy was the same monoclinic phase characterized in different work by TEM and could be produced by direct laser heating of metal in air. Full article

(This article belongs to the Special Issue Advanced Laser Ablation and Damage in Materials)

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13 pages, 7200 KiB

Open AccessArticle

Hydrogenation Properties of the Ti₄₅Zr_38−xY_xNi₁₇ (5 ≤ x ≤ 10) and the Ti_45−zY_zZr₃₈Ni₁₇ (5 ≤ z ≤ 15) Mechanically Alloyed Materials

by Joanna Czub, Akito Takasaki, Andreas Hoser, Manfred Reehuis and Łukasz Gondek

Materials 2024, 17(20), 4946; https://doi.org/10.3390/ma17204946 - 10 Oct 2024

Abstract

The amorphous materials of the Ti₄₅Zr₃₈Ni₁₇ composition synthesized by mechanical alloying are widely recognized for their ability to store hydrogen with gravimetric densities above 2 wt.%. It is also known that those alloys can form a quasicrystalline state [...] Read more.

The amorphous materials of the Ti₄₅Zr₃₈Ni₁₇ composition synthesized by mechanical alloying are widely recognized for their ability to store hydrogen with gravimetric densities above 2 wt.%. It is also known that those alloys can form a quasicrystalline state after thermal treatment and their structural and hydrogen sorption properties can be altered by doping with various elements. Therefore, in this paper, the results of the studies on the Ti₄₅Zr₃₈Ni₁₇ system with yttrium substituted for titanium and zirconium are presented. We demonstrate that these alloys are able to absorb hydrogen with a concentration of up to 2.7 wt.% while retaining their amorphous structure and they transform into the unique glassy-quasicrystal phase upon annealing. Furthermore, we demonstrate that the in-situ hydrogenation of those new materials is an effortless procedure in which the decomposition of the alloy can be avoided. Moreover, we prove that, in that process, hydrogen does not bind to any specific component of the alloy, which would otherwise cause the formation of simple hydrides or nanoclusters. Full article

(This article belongs to the Special Issue Microstructure Characterization and Properties of Intermetallic Alloys/Amorphous Alloys)

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23 pages, 9999 KiB

Open AccessArticle

Optimization of Proportions of Alkali-Activated Slag–Fly Ash-Based Cemented Tailings Backfill and Its Strength Characteristics and Microstructure under Combined Action of Dry–Wet and Freeze–Thaw Cycles

by Jianlin Hu, Zhipeng Meng, Tongtong Gao, Shaohui Dong, Peng Ni, Zhilin Li, Wenlong Yang and Kai Wang

Materials 2024, 17(20), 4945; https://doi.org/10.3390/ma17204945 - 10 Oct 2024

Abstract

To enhance the application of alkali-activated materials in mine filling, cemented tailings backfill was prepared using slag, fly ash, sodium silicate, and NaOH as primary constituents. The effects of the raw material type and dosage on the backfill were examined through a single-factor [...] Read more.

To enhance the application of alkali-activated materials in mine filling, cemented tailings backfill was prepared using slag, fly ash, sodium silicate, and NaOH as primary constituents. The effects of the raw material type and dosage on the backfill were examined through a single-factor experiment. Additionally, response surface methodology (RSM) was utilized to optimize the mixing ratios of the backfill, with a focus on fluidity and compressive strength as key objectives. The evolution of backfill quality and compressive strength under the combined effects of dry–wet and freeze–thaw (DW-FT) cycles was analyzed. The hydration products, microstructure, and pore characteristics of the specimens were analyzed using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and nitrogen adsorption tests (NATs) across varying cycles. The results demonstrate that the optimal backfill composition includes 47.8% fly ash, 6.10% alkali equivalent, and a 1.44 sodium silicate modulus. The macroscopic behavior of the backfill under DW-FT coupling followed this progression: pore initiation → pore expansion → crack formation → crack propagation → structural damage. After a minor initial increase, the backfill strength steadily decreased. Microscopic analysis revealed that the decline in internal cementation products and the deterioration of pore structure were the primary causes of this strength reduction. Thus, the DW-FT coupling can cause significant erosion of the backfill. The technical solutions presented in this paper offer a reference for solid waste utilization and provide valuable insights into the durability of backfill under DW-FT coupling. Full article

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15 pages, 7498 KiB

Open AccessArticle

Enhancing the Lap Shear Performance of Resistance-Welded GF/PP Thermoplastic Composite by Modifying Metal Heating Elements with Silane Coupling Agent

by Wanling Long, Xinyu Zhou, Bing Du, Xiangrong Cheng, Guiyang Su and Liming Chen

Materials 2024, 17(20), 4944; https://doi.org/10.3390/ma17204944 - 10 Oct 2024

Abstract

Thermoplastic composites are gaining widespread application in aerospace and other industries due to their superior durability, excellent damage resistance, and recyclability compared to thermosetting materials. This study aims to enhance the lap shear strength (LSS) of resistance-welded GF/PP (glass fiber-reinforced polypropylene) thermoplastic composites [...] Read more.

Thermoplastic composites are gaining widespread application in aerospace and other industries due to their superior durability, excellent damage resistance, and recyclability compared to thermosetting materials. This study aims to enhance the lap shear strength (LSS) of resistance-welded GF/PP (glass fiber-reinforced polypropylene) thermoplastic composites by modifying stainless steel mesh (SSM) heating elements using a silane coupling agent. The influence of oxidation temperature, solvent properties, and solution pH on the LSS of the welded joints was systematically evaluated. Furthermore, scanning electron microscopy (SEM) was utilized to investigate the SSM surface and assess improvements in interfacial adhesion. The findings indicate that surface treatment promotes increased resin infiltration into the SSM, thereby enhancing the LSS of the resistance-welded joints. Treatment under optimal conditions (500 °C, ethanol solvent, and pH 11) improved LSS by 27.2% compared to untreated joints. Full article

(This article belongs to the Special Issue Advances in Welding Process and Materials (2nd Edition))

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23 pages, 14291 KiB

Open AccessArticle

Degradation Modeling and RUL Prediction of Hot Rolling Work Rolls Based on Improved Wiener Process

by Xuguo Yan, Shiyang Zhou, Huan Zhang and Cancan Yi

Materials 2024, 17(20), 4943; https://doi.org/10.3390/ma17204943 - 10 Oct 2024

Abstract

Hot rolling work rolls are essential components in the hot rolling process. However, they are subjected to high temperatures, alternating stress, and wear under prolonged and complex working conditions. Due to these factors, the surface of the work rolls gradually degrades, which significantly [...] Read more.

Hot rolling work rolls are essential components in the hot rolling process. However, they are subjected to high temperatures, alternating stress, and wear under prolonged and complex working conditions. Due to these factors, the surface of the work rolls gradually degrades, which significantly impacts the quality of the final product. This paper presents an improved degradation model based on the Wiener process for predicting the remaining useful life (RUL) of hot rolling work rolls, addressing the critical need for accurate and reliable RUL estimation to optimize maintenance strategies and ensure operational efficiency in industrial settings. The proposed model integrates pulsed eddy current testing with VMD-Hilbert feature extraction and incorporates a Gaussian kernel into the standard Wiener process to effectively capture complex degradation paths. A Bayesian framework is employed for parameter estimation, enhancing the model’s adaptability in real-time prediction scenarios. The experimental results validate the superiority of the proposed method, demonstrating reductions in RMSE by approximately 85.47% and 41.20% compared to the exponential Wiener process and the RVM model based on a Gaussian kernel, respectively, along with improvements in the coefficient of determination (CD) by 121% and 19.76%. Additionally, the model achieves reductions in MAE by 85.66% and 42.61%, confirming its enhanced predictive accuracy and robustness. Compared to other algorithms from the related literature, the proposed model consistently delivers higher prediction accuracy, with most RUL predictions falling within the 20% confidence interval. These findings highlight the model’s potential as a reliable tool for real-time RUL prediction in industrial applications. Full article

(This article belongs to the Section Materials Physics)

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20 pages, 4721 KiB

Open AccessArticle

Study on the Effect of Hot and Humid Environmental Factors on the Mechanical Properties of Asphalt Concrete

by Xin Yan, Zhigang Zhou, Yingjia Fang, Chongsen Ma and Guangtao Yu

Materials 2024, 17(20), 4942; https://doi.org/10.3390/ma17204942 - 10 Oct 2024

Abstract

To investigate the effect of hot and humid environmental factors on the mechanical properties of asphalt mixtures research, in this paper, the dynamic modulus of asphalt mixtures under the effects of aging, dry–wet cycling, and coupled effects of aging and dry–wet cycling were [...] Read more.

To investigate the effect of hot and humid environmental factors on the mechanical properties of asphalt mixtures research, in this paper, the dynamic modulus of asphalt mixtures under the effects of aging, dry–wet cycling, and coupled effects of aging and dry–wet cycling were measured by the simple performance tester (SPT) system, and the dynamic modulus principal curves were fitted based on the sigmoidal function. The results show that under the aging effect, the dynamic modulus of asphalt mixture increases with the aging degree; the dynamic modulus of short-term aged, medium-term aged, long-term aged, and ultra-long-term aged asphalt mixtures increased by 9.3%, 26.4%, 44.8%, and 57%, respectively, compared to unaged asphalt mixtures at 20 °C and 10 Hz; the high-temperature stability performance is enhanced, and the low temperature cracking resistance performance is enhanced; under the dry–wet cycle, the aging effect of asphalt water is more obvious in the early stage, and dynamic modulus of resilience of the mixture is slightly increased. In the long-term wet–dry cycle process, water on the asphalt and aggregate erosion increased, the structural bearing capacity attenuation, and the dynamic modulus of rebound greatly reduced at 20 °C and 10 Hz. For example, the dynamic modulus of asphalt mixtures with seven wet and dry cycles increased by 3% compared to asphalt mixtures without wet and dry cycles, and the dynamic modulus of asphalt mixtures with 14 cycles of wet and dry cycles and 21 cycles of wet and dry cycles decreased by 10.8% and 16.5%, respectively, compared to asphalt mixtures without wet and dry cycles. The main curve as a whole shifted downward; the high-temperature performance decreased significantly; in the aging wet–dry cycle coupling, the aging asphalt mixture is more susceptible to water erosion, and the first wet–dry cycle after the mix by the degree of water erosion is relatively small, along with the dynamic modulus of rebound. The dynamic modulus of resilience is relatively larger, and the high-temperature performance is relatively better, while the low-temperature performance is worse. Full article

(This article belongs to the Special Issue Experimental Study, Numerical Simulation & Structural Applications of Construction Materials—2nd Edition)

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7 pages, 3381 KiB

Open AccessCommunication

A-C/Au Film with Low Humidity Sensitivity of Friction by Forming Au Transfer Film

by Lulu Pei, Li Ji, Hongxuan Li, Haichao Cai and Yujun Xue

Materials 2024, 17(20), 4941; https://doi.org/10.3390/ma17204941 - 10 Oct 2024

Abstract

Amorphous carbon is recognized as an excellent lubricating material; however, its tribological properties are significantly influenced by humidity. To elucidate the mechanism underlying this humidity dependence and to propose a novel enhancement method, we investigated and compared the tribological properties of hydrogenated amorphous [...] Read more.

Amorphous carbon is recognized as an excellent lubricating material; however, its tribological properties are significantly influenced by humidity. To elucidate the mechanism underlying this humidity dependence and to propose a novel enhancement method, we investigated and compared the tribological properties of hydrogenated amorphous carbon (a-C:H) and amorphous carbon/gold (a-C/Au) composite films. First, the friction coefficient of these carbon films under different humidity conditions was tested using a rotational ball-on-disk tribometer. Subsequently, we analyzed the morphology and structure of the sliding interface employing optical microscopy (OM), Raman spectroscopy, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). Finally, first-principle calculations were carried out to calculate the adsorption energy of water molecules on different surfaces. The results indicate that the friction coefficient of a-C:H film and the area of transfer film increase with the increase of humidity. This phenomenon can be attributed to the fact that water molecules enhance the interaction between the a-C:H film and steel counterfaces. Notably, in contrast, the friction coefficient of a-C/Au film demonstrates low sensitivity to humidity due to the formation of an Au transfer film that exhibits weak interaction with water molecules. These findings provide a promising strategy for developing environment-adaptive amorphous carbon films and play an important role in promoting the development of intelligent lubricating film. Full article

(This article belongs to the Special Issue Carbon-Based Functional Nanomaterials: Preparation, Properties and Applications)

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Materials, Volume 17, Issue 20 (October-2 2024) – 24 articles

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