Materials

15 pages, 4424 KiB

Open AccessArticle

Modification and Enhancing Contribution of Fiber to Asphalt Binders and Their Corresponding Mixtures: A Study of Viscoelastic Properties

by Chao Li, Hao Liu, Yue Xiao, Jixin Li, Tianlei Wang and Longfan Peng

Materials 2023, 16(16), 5727; https://doi.org/10.3390/ma16165727 - 21 Aug 2023

Viewed by 1054

Abstract

The performance of asphalt binders and asphalt mixtures can be enhanced by the inclusion of fiber. The viscoelastic characteristics of fiber-reinforced asphalt binders and their corresponding mixtures were characterized in this study. To generate fiber-reinforced asphalt samples for dynamic shear rheometer (DSR) tests, [...] Read more.

The performance of asphalt binders and asphalt mixtures can be enhanced by the inclusion of fiber. The viscoelastic characteristics of fiber-reinforced asphalt binders and their corresponding mixtures were characterized in this study. To generate fiber-reinforced asphalt samples for dynamic shear rheometer (DSR) tests, polypropylene fibers (PPFs), polyester fibers (PFs), and lignin fibers (LFs) were added into modified asphalt with a ratio of 5wt%. Indirect tensile resilience tests were conducted on the fiber-reinforced asphalt mixture with Marshall samples, which was prepared with a 6.4% of bitumen/aggregate ratio. The addition of fiber can increase the anti-rutting performance of asphalt binders, and also reduce the anti-fatigue performance of asphalt binders to varying degrees. Viscoelastic properties of the fiber-reinforced asphalt binders are highly dependent on the shape of the used fiber. The resistance of the fiber-reinforced asphalt binders to rutting at high temperatures increases with the roughness degree of the fiber’s surface morphology. PPF-reinforced asphalt binders surpass the others in terms of anti-rutting capabilities. The high-temperature deformation resistance of the PPF-reinforced asphalt mixture is stronger, whereas the low-temperature crack resistance of the PF-reinforced asphalt mixture is stronger, which can be observed from the master curve of indirect tensile resilient modulus. Full article

(This article belongs to the Topic Materials for Carbon-Neutral Infrastructures)

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17 pages, 2607 KiB

Open AccessArticle

Nitrate-Nitrogen Adsorption Characteristics and Mechanisms of Various Garden Waste Biochars

by Jingjing Yao, Zhiyi Wang, Mengfan Liu, Bing Bai and Chengliang Zhang

Materials 2023, 16(16), 5726; https://doi.org/10.3390/ma16165726 - 21 Aug 2023

Cited by 3 | Viewed by 988

Abstract

Nitrate-nitrogen (NO₃⁻–N) removal and garden waste disposal are critical concerns in urban environmental protection. In this study, biochars were produced by pyrolyzing various garden waste materials, including grass clippings (GC), Rosa chinensis Jacq. branches (RC), Prunus persica branches (PP), [...] Read more.

Nitrate-nitrogen (NO₃⁻–N) removal and garden waste disposal are critical concerns in urban environmental protection. In this study, biochars were produced by pyrolyzing various garden waste materials, including grass clippings (GC), Rosa chinensis Jacq. branches (RC), Prunus persica branches (PP), Armeniaca vulgaris Lam. branches (AV), Morus alba Linn. sp. branches (MA), Platycladus orientalis (L.) Franco branches (PO), Pinus tabuliformis Carrière branches (PT), and Sophorajaponica Linn. branches (SL) at three different temperatures (300 °C, 500 °C, and 700 °C). These biochars, labeled as GC300, GC500, GC700, and so on., were then used to adsorb NO₃⁻–N under various conditions, such as initial pH value, contact time, initial NO₃⁻–N concentration, and biochar dosage. Kinetic data were analyzed by pseudo-first-order and pseudo-second-order kinetic models. The equilibrium adsorption data were evaluated by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models. The results revealed that the biochar yields varied between 14.43% (PT700) and 47.09% (AV300) and were significantly influenced by the type of garden waste and decreased with increasing pyrolysis temperature, while the pH and ash content showed an opposite trend (p < 0.05). The efficiency of NO₃⁻–N removal was significantly influenced by the type of feedstock, preparation process, and adsorption conditions. Higher pH values had a negative influence on NO₃⁻–N adsorption, while longer contact time, higher initial concentration of NO₃⁻–N, and increased biochar dosage positively affected NO₃⁻–N adsorption. Most of the kinetic data were better fitted to the pseudo-second-order kinetic model (0.998 > R² > 0.927). Positive b values obtained from the Temkin model indicated an exothermic process of NO₃⁻–N adsorption. The Langmuir model provided better fits for more equilibrium adsorption data than the Freundlich model, with the maximum NO₃⁻–N removal efficiency (62.11%) and adsorption capacity (1.339 mg·g⁻¹) in PO700 under the conditions of pH = 2, biochar dosage = 50 mg·L⁻¹, and a reaction time of 24 h. The outcomes of this study contribute valuable insights into garden waste disposal and NO₃⁻–N removal from wastewater, providing a theoretical basis for sustainable environmental management practices. Full article

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20 pages, 1966 KiB

Open AccessReview

Toughening of Ni-Mn-Based Polycrystalline Ferromagnetic Shape Memory Alloys

by Siyao Ma, Xuexi Zhang, Guangping Zheng, Mingfang Qian and Lin Geng

Materials 2023, 16(16), 5725; https://doi.org/10.3390/ma16165725 - 21 Aug 2023

Cited by 1 | Viewed by 961

Abstract

Solid-state refrigeration technology is expected to replace conventional gas compression refrigeration technology because it is environmentally friendly and highly efficient. Among various solid-state magnetocaloric materials, Ni-Mn-based ferromagnetic shape memory alloys (SMAs) have attracted widespread attention due to their multifunctional properties, such as their [...] Read more.

Solid-state refrigeration technology is expected to replace conventional gas compression refrigeration technology because it is environmentally friendly and highly efficient. Among various solid-state magnetocaloric materials, Ni-Mn-based ferromagnetic shape memory alloys (SMAs) have attracted widespread attention due to their multifunctional properties, such as their magnetocaloric effect, elastocaloric effect, barocaloric effect, magnetoresistance, magnetic field-induced strain, etc. Recently, a series of in-depth studies on the thermal effects of Ni-Mn-based magnetic SMAs have been carried out, and numerous research results have been obtained. It has been found that poor toughness and cyclic stability greatly limit the practical application of magnetic SMAs in solid-state refrigeration. In this review, the influences of element doping, microstructure design, and the size effect on the strength and toughness of Ni-Mn-based ferromagnetic SMAs and their underlying mechanisms are systematically summarized. The pros and cons of different methods in enhancing the toughness of Ni-Mn-based SMAs are compared, and the unresolved issues are analyzed. The main research directions of Ni-Mn-based ferromagnetic SMAs are proposed and discussed, which are of scientific and technological significance and could promote the application of Ni-Mn-based ferromagnetic SMAs in various fields. Full article

(This article belongs to the Special Issue Physical Metallurgy of Metals and Alloys II)

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16 pages, 6599 KiB

Open AccessArticle

Skin Friction: Mechanical and Tribological Characterization of Different Papers Used in Everyday Life

by Luís Vilhena, Luís Afonso and Amílcar Ramalho

Materials 2023, 16(16), 5724; https://doi.org/10.3390/ma16165724 - 21 Aug 2023

Viewed by 810

Abstract

The coefficient of friction for different contacting materials against skin is mainly influenced by the nature of the materials (synthetic and natural fabrics), mechanical contact parameters (interfacial pressure and sliding velocities), and physiological skin conditions (ambient humidity and skin moisture content). In the [...] Read more.

The coefficient of friction for different contacting materials against skin is mainly influenced by the nature of the materials (synthetic and natural fabrics), mechanical contact parameters (interfacial pressure and sliding velocities), and physiological skin conditions (ambient humidity and skin moisture content). In the present research work, seven different types of papers used in everyday life were analyzed. The physical properties of these materials were determined through tensile tests and friction tests. By comparing mechanical properties with coefficient of friction, it was possible to conclude that the coefficient of friction is strongly correlated with the mechanical properties. Full article

(This article belongs to the Special Issue Leather, Textile and Bio-Based Materials: Production Processes, Environmental Impact and Life Cycle Assessment)

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20 pages, 6208 KiB

Open AccessReview

Recent Progress of Layered Double Hydroxide-Based Materials in Wastewater Treatment

by Yanli Fu, Xiaoqian Fu, Wen Song, Yanfei Li, Xuguang Li and Liangguo Yan

Materials 2023, 16(16), 5723; https://doi.org/10.3390/ma16165723 - 21 Aug 2023

Cited by 5 | Viewed by 1684

Abstract

Layered double hydroxides (LDHs) can be used as catalysts and adsorbents due to their high stability, safety, and reusability. The preparation of modified LDHs mainly includes coprecipitation, hydrothermal, ion exchange, calcination recovery, and sol–gel methods. LDH-based materials have high anion exchange capacity, good [...] Read more.

Layered double hydroxides (LDHs) can be used as catalysts and adsorbents due to their high stability, safety, and reusability. The preparation of modified LDHs mainly includes coprecipitation, hydrothermal, ion exchange, calcination recovery, and sol–gel methods. LDH-based materials have high anion exchange capacity, good thermal stability, and a large specific surface area, which can effectively adsorb and remove heavy metal ions, inorganic anions, organic pollutants, and oil pollutants from wastewater. Additionally, they are heterogeneous catalysts and have excellent catalytic effect in the Fenton system, persulfate-based advanced oxidation processes, and electrocatalytic system. This review ends with a discussion of the challenges and future trends of the application of LDHs in wastewater treatment. Full article

(This article belongs to the Special Issue Development and Modification of New or Recycled Materials and Technological Processes toward Sustainable Development)

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16 pages, 2597 KiB

Open AccessArticle

Selective Oxidation of Cyclohexanone to Adipic Acid Using Molecular Oxygen in the Presence of Alkyl Nitrites and Transition Metals as Catalysts

by Dawid Lisicki, Beata Orlińska, Tomasz Martyniuk, Krzysztof Dziuba and Jakub Bińczak

Materials 2023, 16(16), 5722; https://doi.org/10.3390/ma16165722 - 21 Aug 2023

Viewed by 1100

Abstract

This paper presents a not previously reported catalytic system consisting of transition metals Co²⁺ and Mn²⁺ and alkyl nitrites R-ONO for the oxidation of cyclohexanone with oxygen to adipic acid. The influence of type and amount of catalyst, temperature, time, and [...] Read more.

This paper presents a not previously reported catalytic system consisting of transition metals Co²⁺ and Mn²⁺ and alkyl nitrites R-ONO for the oxidation of cyclohexanone with oxygen to adipic acid. The influence of type and amount of catalyst, temperature, time, and type of raw material on conversion and product composition were determined. In addition, the oxidation of selected cyclic ketones such as cyclopentanone, cyclohexanone, cyclooctanone, cyclododecanone, 2-methylcyclohexanone, 3-methylcyclohexanone, and 4-methylcyclohexanone in acetic acid as solvent was performed. The results showed that R-ONO systems, under established reaction conditions, form NO·radicals, which oxidize to NO₂ under a strong oxidization reaction environment. The Co²⁺/Mn²⁺/NO₂ system was shown to be highly active in the oxidation of cyclic ketones with oxygen. Full article

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11 pages, 2367 KiB

Open AccessArticle

Application of Polymer-Embedded Tetrabutylammonium Bromide (TBAB) Membranes for the Selective Extraction of Metal Ions from Aqueous Solutions

by Beata Pospiech

Materials 2023, 16(16), 5721; https://doi.org/10.3390/ma16165721 - 21 Aug 2023

Viewed by 803

Abstract

The selective extraction of metals from aqueous solutions is a very important stage in the hydrometallurgical processing of metallic waste. Leach solutions are usually a multicomponent mixture. The main impurity of aqueous solutions obtained after leaching using inorganic acids is iron. In this [...] Read more.

The selective extraction of metals from aqueous solutions is a very important stage in the hydrometallurgical processing of metallic waste. Leach solutions are usually a multicomponent mixture. The main impurity of aqueous solutions obtained after leaching using inorganic acids is iron. In this work, the membrane separation of iron(III) from nickel(II), cobalt(II), and lithium(I) was studied. The facilitated transport of metal ions using polymer inclusion membranes (PIMs) with tetrabutylammonium bromide (TBAB) as an ion carrier under various conditions was analyzed in detail. Several factors, such as the ion carrier concentration in the membrane as well as the effect of the inorganic acid concentration in the source/receiving phases on the kinetic parameters, were investigated. The results show that ionic liquid TBAB is a very selective ion carrier of Fe(III) towards Ni(II), Co(II), and Li(I). Full article

(This article belongs to the Special Issue Functional Cellulosic Materials)

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18 pages, 6558 KiB

Open AccessArticle

Artificial Neural Networks for Predicting the Diameter of Electrospun Nanofibers Synthesized from Solutions/Emulsions of Biopolymers and Oils

by Guadalupe Cuahuizo-Huitzil, Octavio Olivares-Xometl, María Eugenia Castro, Paulina Arellanes-Lozada, Francisco J. Meléndez-Bustamante, Ivo Humberto Pineda Torres, Claudia Santacruz-Vázquez and Verónica Santacruz-Vázquez

Materials 2023, 16(16), 5720; https://doi.org/10.3390/ma16165720 - 21 Aug 2023

Viewed by 887

Abstract

In the present work, different configurations of nt iartificial neural networks (ANNs) were analyzed in order to predict the experimental diameter of nanofibers produced by means of the electrospinning process and employing polyvinyl alcohol (PVA), PVA/chitosan (CS) and PVA/aloe vera (Av) solutions. [...] Read more.

In the present work, different configurations of nt iartificial neural networks (ANNs) were analyzed in order to predict the experimental diameter of nanofibers produced by means of the electrospinning process and employing polyvinyl alcohol (PVA), PVA/chitosan (CS) and PVA/aloe vera (Av) solutions. In addition, gelatin type A (GT)/alpha-tocopherol (α-TOC), PVA/olive oil (OO), PVA/orange essential oil (OEO), and PVA/anise oil (AO) emulsions were used. The experimental diameters of the nanofibers electrospun from the different tested systems were obtained using scanning electron microscopy (SEM) and ranged from 93.52 nm to 352.1 nm. Of the three studied ANNs, the one that displayed the best prediction results was the one with three hidden layers with the flow rate, voltage, viscosity, and conductivity variables. The calculation error between the experimental and calculated diameters was 3.79%. Additionally, the correlation coefficient (R²) was identified as a function of the ANN configuration, obtaining values of 0.96, 0.98, and 0.98 for one, two, and three hidden layer(s), respectively. It was found that an ANN configuration having more than three hidden layers did not improve the prediction of the experimental diameter of synthesized nanofibers. Full article

(This article belongs to the Topic Artificial Intelligence and Computational Methods: Modeling, Simulations and Optimization of Complex Systems)

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14 pages, 4967 KiB

Open AccessArticle

Properties of Gangue Powder Modified Fly Ash-Based Geopolymer

by Tianhao Zhang, Zhenghui Yang, Dongsheng Zhang and Qiuning Yang

Materials 2023, 16(16), 5719; https://doi.org/10.3390/ma16165719 - 21 Aug 2023

Viewed by 739

Abstract

The environmental and economic problems caused by gangue accumulation continue to worsen. Therefore, the implementation of a cost-effective method for utilizing gangue resources is urgent. In this study, different gangue powder (GP) contents (0%, 10%, 20%, 30%, 40%, and 50%) for mechanical–thermal activation [...] Read more.

The environmental and economic problems caused by gangue accumulation continue to worsen. Therefore, the implementation of a cost-effective method for utilizing gangue resources is urgent. In this study, different gangue powder (GP) contents (0%, 10%, 20%, 30%, 40%, and 50%) for mechanical–thermal activation were used to modify a fly ash-based geopolymer (FAG). Further, the effect of GP was revealed by investigating the setting time, fluidity, porosity, water absorption rate, mechanical properties, drying shrinkage, and microstructure. Results showed that the addition of GP reduced the fluidity and setting time of gangue powder—fly ash-base geopolymer (GPFAG), improved density, and decreased the water absorption rate of GPFAG. Moreover, its mechanical properties gradually improved. Compared with GPFAG0 (FAG with 0% GP), the 28-d compressive and flexural strengths of GPFAG50 (FAG with 50% GP) increased by 246.4% and 136.8%, respectively. The incorporation of GP increased the drying shrinkage. The results of XRD and FTIR analyses showed that the addition of GP increased the production of amorphous silica–aluminate gels, such as N-S-A-H and C-S-A-H. Moreover, strong Si-O-T vibrational peaks appeared in the range 743–1470 cm⁻¹, characterizing the GPFAG strength and reaction degree. Full article

(This article belongs to the Special Issue Research on Alkali-Activated Materials)

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16 pages, 4073 KiB

Open AccessArticle

Bioactive Polyoxymethylene Composites: Mechanical and Antibacterial Characterization

by Paulina Kaczor, Patrycja Bazan and Stanisław Kuciel

Materials 2023, 16(16), 5718; https://doi.org/10.3390/ma16165718 - 21 Aug 2023

Cited by 2 | Viewed by 737

Abstract

The aim of this study is to analyze the strength and antibacterial properties of composites based on structural polyoxymethylene. The base material was modified with the most used antibacterial additives, such as silver nanoparticles, copper oxide, zinc oxide, and titanium oxide. Basic strength [...] Read more.

The aim of this study is to analyze the strength and antibacterial properties of composites based on structural polyoxymethylene. The base material was modified with the most used antibacterial additives, such as silver nanoparticles, copper oxide, zinc oxide, and titanium oxide. Basic strength and low-cycle fatigue tests were conducted to determine the dissipation energy of the material. The composites were also tested for antibacterial properties against two strains of bacteria: Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538. Strength properties showed no significant changes in the mechanical behavior of the tested composites against the matrix material. The best antibacterial additive was the addition of titanium oxide nanoparticles, providing 100% efficacy against Escherichia coli and almost 100% biocidal efficacy against Staphylococcus aureus. The other antibacterial additives showed biocidal efficacy of about 30–40% against the unmodified material. The added value of the work is the consistency in the methodology of testing materials modified with antibacterial additives, as well as the same compactness of the introduced additives. This study makes it clear which of the introduced additives has the highest biocidal activity. Full article

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15 pages, 11832 KiB

Open AccessArticle

Effects of Surface Treatment Method Forming New Nano/Micro Hierarchical Structures on Attachment and Proliferation of Osteoblast-like Cells

by Jae-Seung Im, Hyunsuk Choi, Hyun-Wook An, Tae-Yub Kwon and Min-Ho Hong

Materials 2023, 16(16), 5717; https://doi.org/10.3390/ma16165717 - 21 Aug 2023

Cited by 4 | Viewed by 1121

Abstract

Titanium (Ti) and Ti-based alloys are commonly used in dental implants, and surface modifications of dental implants are important for achieving osseointegration (i.e., direct connection between the implant surface and bone). This study investigated the effect of an eco-friendly etching solution—a hydrogen peroxide–sodium [...] Read more.

Titanium (Ti) and Ti-based alloys are commonly used in dental implants, and surface modifications of dental implants are important for achieving osseointegration (i.e., direct connection between the implant surface and bone). This study investigated the effect of an eco-friendly etching solution—a hydrogen peroxide–sodium bicarbonate mixture—on the surface properties and contact angles of osteoblast adhesion and proliferation on Ti surfaces. Disk-shaped Ti specimens were prepared using different surface treatments (machining, sandblasting, and sandblasting/acid-etching), and they were immersed in the etching solution and ultrasonically cleaned. Surface characterization was performed using scanning electron microscopy, digital microscopy, contact angle analysis, and X-ray photoelectron spectroscopy. MG-63 osteoblasts were cultured on the specimens, and their adhesion to the specimen surface and proliferation were examined using staining and the MTT assay, respectively. Additional etching with the etching solution caused the formation of nano/micro hierarchical structures, increased surface roughness, and enhanced hydrophilicity. Osteoblast adhesion and proliferation were found to improve on the modified surfaces. The eco-friendly etching method has the potential to enhance the biological properties of Ti implant surfaces and thereby improve dental implant performance. Full article

(This article belongs to the Section Biomaterials)

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14 pages, 5444 KiB

Open AccessArticle

Process Optimization, Microstructure and Mechanical Properties of Wire Arc Additive Manufacturing of Aluminum Alloy by Using DP-GMAW Based on Response Surface Method

by Wenbo Du, Guorui Sun, Yue Li and Chao Chen

Materials 2023, 16(16), 5716; https://doi.org/10.3390/ma16165716 - 21 Aug 2023

Cited by 1 | Viewed by 864

Abstract

Double-pulsed gas metal arc welding (DP-GMAW) is a high-performance welding method with low porosity and high frequency. Periodic shrinkage and expansion of the melt pool during DP-GMAW leads to unusual remelting, and the re-solidification behavior of the weld metal can significantly refine the [...] Read more.

Double-pulsed gas metal arc welding (DP-GMAW) is a high-performance welding method with low porosity and high frequency. Periodic shrinkage and expansion of the melt pool during DP-GMAW leads to unusual remelting, and the re-solidification behavior of the weld metal can significantly refine the weld structure. The advantages of DP-GMAW have been proven. In order to better apply DP-GMAW to aluminum alloy arc additive manufacturing, in this paper, the single-pass deposition layer parameters (double-pulse amplitude, double-pulse frequency and travel speed) of DP-GMAW will be optimized using the response surface method (RSM) with the width, height, and penetration of the deposition layer as the response values to find the superior process parameters applicable to the additive manufacturing of aluminum alloy DP-GMAW. The results show that the aluminum alloy components made by DP-GMAW additive are well formed. Due to the stirring of double-pulse arc and the abnormal remelting and solidification of metal, the microstructures in the middle and top areas show disordered growth. The average ultimate tensile strength of the transverse tensile specimen of the member can reach 175.2 MPa, and the elongation is 10.355%. Full article

(This article belongs to the Special Issue Additive Manufacturing of Aluminum Alloys and Aluminum Matrix Composites)

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20 pages, 23621 KiB

Open AccessArticle

A Study of Repair Mortars for Restoration of Wall Painted Plasters in a Hypogeum Rock-Cut Church of Matera (Southern Italy)

by Manuel Giandomenico, Filippo Edoardo Capasso, Sokol Muca, Maria Carolina Gaetani, Giovanni Quarta, Sara Iafrate, Davide Melica and Angela Calia

Materials 2023, 16(16), 5715; https://doi.org/10.3390/ma16165715 - 21 Aug 2023

Cited by 1 | Viewed by 715

Abstract

Several lime mortars for the repair of painted plasters of the rock-cut church of Ss. Pietro and Paolo in Matera were studied. They were designed taking into account both aesthetic criteria that need to be fulfilled in the field of paintings restoration, and [...] Read more.

Several lime mortars for the repair of painted plasters of the rock-cut church of Ss. Pietro and Paolo in Matera were studied. They were designed taking into account both aesthetic criteria that need to be fulfilled in the field of paintings restoration, and physical–mechanical compatibility with the original materials on site, i.e., the pre-existing plasters and the supporting rock. Mixes with calcareous and silica aggregates, based on different grain size proportions, were prepared to fill missing portions of the original painted plaster. The effects of the mineralogical nature and size of the aggregates on the characteristics and properties of the mixes were investigated in relation to the microstructure, physical–mechanical features and resistance to salt ageing. At the end of the experimental campaign, the overall performance was evaluated. Full article

(This article belongs to the Special Issue Advanced Materials & Methods for Heritage & Archaeology)

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11 pages, 3571 KiB

Open AccessArticle

The Effect of Sensitization on the Susceptibility of AISI 316L Biomaterial to Pitting Corrosion

by Viera Zatkalíková, Milan Uhríčik, Lenka Markovičová, Lucia Pastierovičová and Lenka Kuchariková

Materials 2023, 16(16), 5714; https://doi.org/10.3390/ma16165714 - 21 Aug 2023

Viewed by 862

Abstract

Due to the combination of high corrosion resistance and suitable mechanical properties, AISI 316L stainless steel is extensively used as the biomaterial for surgical implants. However, heat exposure in inappropriate temperatures can cause its sensitization accompanied by chromium depletion along the grain boundaries. [...] Read more.

Due to the combination of high corrosion resistance and suitable mechanical properties, AISI 316L stainless steel is extensively used as the biomaterial for surgical implants. However, heat exposure in inappropriate temperatures can cause its sensitization accompanied by chromium depletion along the grain boundaries. This study deals with an assessment of the susceptibility of sensitized AISI 316L biomaterial to pitting under conditions simulating the internal environment of the human body (Hank’s balanced salt solution, 37 ± 0.5 °C). The resistance to pitting corrosion is tested by the potentiodynamic polarization and by the 50-day exposure immersion test. Corrosion damage after the exposure immersion test is evaluated in the specimens’ cross-sections by optical microscope and SEM. Despite passive behavior in potentiodynamic polarization and shallow, slight corrosion damage observed after exposure, the sensitized AISI 316L biomaterial could represent a risk, especially in long-term implantation even after the chemical removal of high-temperature oxides. Full article

(This article belongs to the Special Issue Research on Metallic Implant Biomaterials)

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21 pages, 5361 KiB

Open AccessArticle

Performance of Anticorrosive Paint Systems for Carbon Steel in the Antarctic Marine Environment

by Rosa Vera, Margarita Bagnara, Rodrigo Henríquez, Lisa Muñoz, Paula Rojas and Andrés Díaz-Gómez

Materials 2023, 16(16), 5713; https://doi.org/10.3390/ma16165713 - 21 Aug 2023

Viewed by 2853

Abstract

This study evaluated the behavior of three paint systems exposed to the Antarctic marine environment for 45 months compared to a control of uncoated carbon steel with a determined corrosion rate. At the study site, all environmental conditions, solar radiation, and the concentration [...] Read more.

This study evaluated the behavior of three paint systems exposed to the Antarctic marine environment for 45 months compared to a control of uncoated carbon steel with a determined corrosion rate. At the study site, all environmental conditions, solar radiation, and the concentration of environmental pollutants (

{Cl}^{-}

and SO₂) were evaluated. The paint systems differed in terms of the primer and top coat. Coated samples were studied before and after exposure. They were evaluated visually and using SEM to determine adhesion, abrasion, and contact angle; using the Evans X-Cut Tape Test; using ATR-FTIR spectroscopy to analyze the state of aging of the top layer; and using electrochemical impedance spectroscopy (EIS) for coat protection characterization. The corrosion rate obtained for steel was 85.64 µm year⁻¹, which aligned with a C5 environmental corrosivity category. In general, the evaluation in the period studied showed the paint systems had good adhesion and resistance to delamination, without the presence of surface rust, and exhibited some loss of brightness, an increase in the abrasion index, and a decrease in the percentage of reflectance due to aging. EIS showed good protection capability of the three coating schemes. In general, this type of paint system has not previously been evaluated in an extreme environment after 45 months of exposure to the environment. The results showed that the best behavior was found for the system whose top layer was acrylic–aliphatic polyurethane. Full article

(This article belongs to the Special Issue Friction, Corrosion and Protection of Material Surfaces)

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10 pages, 2924 KiB

Open AccessCommunication

Charge Carrier Dynamics in Non-Fullerene Acceptor-Based Organic Solar Cells: Investigating the Influence of Processing Additives Using Transient Absorption Spectroscopy

by Gayoung Ham, Damin Lee, Changwoo Park and Hyojung Cha

Materials 2023, 16(16), 5712; https://doi.org/10.3390/ma16165712 - 21 Aug 2023

Viewed by 1202

Abstract

In this study, we present a comprehensive investigation into the charge generation mechanism in bulk-heterojunction organic solar cells employing non-fullerene acceptors (NFAs) both with and without the presence of processing additives. While photovoltaic devices based on Y6 or BTP-eC9 have shown remarkable power [...] Read more.

In this study, we present a comprehensive investigation into the charge generation mechanism in bulk-heterojunction organic solar cells employing non-fullerene acceptors (NFAs) both with and without the presence of processing additives. While photovoltaic devices based on Y6 or BTP-eC9 have shown remarkable power conversion efficiencies, the underlying charge generation mechanism in polymer:NFA blends remains poorly understood. To shed light on this, we employ transient absorption (TA) spectroscopy to elucidate the charge transfer pathway within a blend of the donor polymer PM6 and NFAs. Interestingly, the charge carrier lifetimes of neat Y6 and BTP-eC9 are comparable, both reaching up to 20 ns. However, the PM6:BTP-eC9 blend exhibits substantially higher charge carrier generation and a longer carrier lifetime compared to PM6:Y6 blend films, leading to superior performance. By comparing TA data obtained from PM6:Y6 or PM6:BTP-eC9 blend films with and without processing additives, we observe significantly enhanced charge carrier generation and prolonged charge carrier lifetimes in the presence of these additives. These findings underscore the potential of manipulating excited species as a promising avenue for further enhancing the performance of organic solar cells. Moreover, this understanding contributes to the advancement of NFA-based systems and the optimization of charge transfer processes in polymer:NFA blends. Full article

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13 pages, 1608 KiB

Open AccessArticle

Performance Analysis of High-Performance Concrete Materials in Civil Construction

by Yongguang Han and Tianhua Zhou

Materials 2023, 16(16), 5711; https://doi.org/10.3390/ma16165711 - 21 Aug 2023

Cited by 2 | Viewed by 1007

Abstract

This paper develops the mechanical and durable samples of C50 high-performance concrete, studies the mechanical properties, crack resistance, sulfate attack resistance, frost resistance, and impermeability of concrete with different mineral admixtures of mineral powder and fly ash, and obtains the best mineral admixture [...] Read more.

This paper develops the mechanical and durable samples of C50 high-performance concrete, studies the mechanical properties, crack resistance, sulfate attack resistance, frost resistance, and impermeability of concrete with different mineral admixtures of mineral powder and fly ash, and obtains the best mineral admixture of mineral powder and fly ash to improve the performance of high-performance concrete. The results show that the doping effect is the best when the ratio of prepared mineral powder to fly ash is 3:2. With the increase in the mineral powder–fly ash admixture, the slump and expansion of high-performance concrete decrease rapidly at first and then slowly. In total, 60% doping is the turning point; the compressive and flexural strengths of concrete decreased slowly at first and then rapidly. Taking 30% of the admixture as the turning point, 35% of the mineral powder fly ash is generally selected. By mixing and adding a certain proportion of fly ash and mineral powder admixtures, the crack resistance of concrete is enhanced, and the shrinkage and cracking are reduced. The corrosion resistance coefficient will exceed 88%, the relative dynamic elastic modulus will exceed 95%, and the impermeability grade will reach P17. The durability of concrete can be improved by adding mineral admixtures. Full article

(This article belongs to the Special Issue Ultra High Performance Concrete (UHPC): Current and Future Research)

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22 pages, 7915 KiB

Open AccessReview

Review on Multicatalytic Behavior of Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ Ceramic

by Akshay Gaur, Chirag Porwal, Imed Boukhris, Vishal Singh Chauhan and Rahul Vaish

Materials 2023, 16(16), 5710; https://doi.org/10.3390/ma16165710 - 21 Aug 2023

Cited by 2 | Viewed by 1043

Abstract

Ferroelectric materials are known to possess multicatalytic abilities that are nowadays utilized for removing organic pollutants from water via piezocatalysis, photocatalysis, piezo-photocatalysis, and pyrocatalysis processes. The Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ (BCZTO) ceramic is one such ferroelectric composition [...] Read more.

Ferroelectric materials are known to possess multicatalytic abilities that are nowadays utilized for removing organic pollutants from water via piezocatalysis, photocatalysis, piezo-photocatalysis, and pyrocatalysis processes. The Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ (BCZTO) ceramic is one such ferroelectric composition that has been extensively studied for electrical and electronic applications. Furthermore, the BCZTO ceramic has also shown remarkable multicatalytic performance in water-cleaning applications. The present review explores the potentiality of BCZTO for water-cleaning and bacterial-killing applications. It also highlights the fundamentals of ferroelectric ceramics, the importance of electric poling, and the principles underlying piezocatalysis, photocatalysis, and pyrocatalysis processes in addition to the multicatalytic capability of ferroelectric BCZTO ceramic. Full article

(This article belongs to the Special Issue Multicatalytic Ferroelectrics)

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13 pages, 8068 KiB

Open AccessEditor’s ChoiceArticle

Effect of Tempering Temperature on Hydrogen Embrittlement of SCM440 Tempered Martensitic Steel

by Sang-Gyu Kim, Jae-Yun Kim and Byoungchul Hwang

Materials 2023, 16(16), 5709; https://doi.org/10.3390/ma16165709 - 21 Aug 2023

Viewed by 1223

Abstract

The effect of tempering temperature on the hydrogen embrittlement characteristics of SCM440 tempered martensitic steels was investigated in terms of their microstructure and hydrogen desorption behavior. The microstructures were characterized using scanning and transmission electron microscopy, as well as X-ray diffraction and electron [...] Read more.

The effect of tempering temperature on the hydrogen embrittlement characteristics of SCM440 tempered martensitic steels was investigated in terms of their microstructure and hydrogen desorption behavior. The microstructures were characterized using scanning and transmission electron microscopy, as well as X-ray diffraction and electron backscattered diffraction analysis. Thermal desorption analysis (TDA) was performed to examine the amount and trapping behavior of hydrogen. The cementite morphology of the SCM440 tempered martensitic steels gradually changed from a long lamellar shape to a segmented short-rod shape with an increasing tempering temperature. A slow strain rate tensile test was conducted after electrochemical hydrogen charging to evaluate the hydrogen embrittlement resistance. The hydrogen embrittlement resistance of the SCM440 tempered martensitic steels increased with an increasing tempering temperature because of the decrease in the fraction of the low-angle grain boundaries and dislocation density. The low-angle grain boundaries and dislocations, which acted as reversible hydrogen trap sites, were critical factors in determining the hydrogen embrittlement resistance, and this was supported by the decreased diffusible hydrogen content as measured by TDA. Fine carbides formed in the steel tempered at a relatively higher temperature acted as irreversible hydrogen trap sites and contributed to improving the hydrogen embrittlement resistance. Our findings can suggest that the tempering temperature of SCM440 tempered martensitic steel plays an important role in determining its hydrogen embrittlement resistance. Full article

(This article belongs to the Section Metals and Alloys)

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15 pages, 4064 KiB

Open AccessArticle

In Silico Guided Design of Metal/Semiconductor Photocatalysts: A Case of Cu-Modified TiO₂ for Ciprofloxacin Degradation

by Marija Kovačević, Sanja Živković, Miloš Ognjanović, Miloš Momčilović, Dubravka Relić and Dragana Vasić Anićijević

Materials 2023, 16(16), 5708; https://doi.org/10.3390/ma16165708 - 21 Aug 2023

Cited by 1 | Viewed by 870

Abstract

(1) Background: An increasing use of pharmaceutics imposes a need for the permanent development of efficient strategies, including the tailoring of highly specific new materials for their removal from the environment. Photocatalytic degradation has been the subject of increasing interest of the researchers [...] Read more.

(1) Background: An increasing use of pharmaceutics imposes a need for the permanent development of efficient strategies, including the tailoring of highly specific new materials for their removal from the environment. Photocatalytic degradation has been the subject of increasing interest of the researchers in the field. (2) Methods: This paper is focused on the investigation of the possibility to deposit a thin metal layer on a TiO₂ surface and study its photocatalytic performance for the degradation of ciprofloxacin using a combination of theoretical and experimental methods. (3) Results: Based on the extensive DFT screening of 24 d-metals’ adhesion on TiO₂, Cu was selected for further work, due to the satisfactory expected stability and good availability. The (Cu)TiO₂ was successfully synthesized and characterized with XRD, SEM+EDS and UV-Vis spectrophotometry. The uniformly distributed copper on the TiO₂ surface corresponds to the binding on high-affinity oxygen-rich sites, as proposed with DFT calculations. The photocatalytic degradation rate of ciprofloxacin was improved by about a factor of 1.5 compared to the bare non-modified TiO₂. (4) Conclusions: The observed result was ascribed to the ability of adsorbed Cu to impede the agglomeration of TiO₂ and increase the active catalytic area, and bandgap narrowing predicted with DFT calculations. Full article

(This article belongs to the Section Catalytic Materials)

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12 pages, 5349 KiB

Open AccessArticle

Experimental Study of Dynamic Tensile Strength of Steel-Fiber-Reinforced Self-Compacting Concrete Using Modified Hopkinson Bar

by Jian Ma, Yifei Huo, Ning Wang, Zhang Sun, Liang Bian and Ruiyuan Huang

Materials 2023, 16(16), 5707; https://doi.org/10.3390/ma16165707 - 20 Aug 2023

Viewed by 746

Abstract

As a typical brittle material, the tensile strength of concrete is much lower than its compressive strength. The main failure mode of concrete buildings under explosive and impact loading is spalling, so it is crucial to understand the dynamic tensile performance of concrete. [...] Read more.

As a typical brittle material, the tensile strength of concrete is much lower than its compressive strength. The main failure mode of concrete buildings under explosive and impact loading is spalling, so it is crucial to understand the dynamic tensile performance of concrete. This paper presents an experimental study on the dynamic tensile strength of steel-fiber-reinforced self-compacting concrete (SFRSCC). Specimens of two different self-compacting concrete (SCC) mixes (C40 and C60) and four different fiber volume fractions (0.5%, 1.0%, 1.5%, and 2.0%) are fabricated. Dynamic tensile strengths of SFRSCC are obtained using a modified Hopkinson bar system. The relationships between the dynamic tensile strength of the corresponding SCC mix, the quasi-static compressive strength, and the fiber volume fraction are discussed. An empirical equation is proposed. It is shown that SFRSCC with high compressive strength has higher dynamic tensile strength than low-strength SFRSCC for the same fiber content, and the dynamic tensile strength of SFRSCC possesses an approximately linear relation with the fiber volume fraction. The mechanism underlying this fiber-reinforcement effect is investigated. Full article

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

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21 pages, 6695 KiB

Open AccessArticle

Experimental Study of the Shear Performance of Combined Concrete–ECC Beams without Web Reinforcement

by Kai Cheng, Yulin Du, Haiyan Wang, Rui Liu, Yu Sun, Zhichao Lu and Lingkun Chen

Materials 2023, 16(16), 5706; https://doi.org/10.3390/ma16165706 - 20 Aug 2023

Cited by 1 | Viewed by 870

Abstract

Background: Shear damage of beams is typically brittle damage that is significantly more detrimental than flexural damage. Purpose: Based on the super-high toughness and good crack control ability of engineered cementitious composites (ECC), the shear performance of concrete–ECC beams was investigated by replacing [...] Read more.

Background: Shear damage of beams is typically brittle damage that is significantly more detrimental than flexural damage. Purpose: Based on the super-high toughness and good crack control ability of engineered cementitious composites (ECC), the shear performance of concrete–ECC beams was investigated by replacing a portion of the concrete in the tensile zone of reinforced concrete beams with ECC and employing high-strength reinforcing bars to design concrete–ECC beams. The purpose of this investigation is to elucidate and clarify the shear performance of concrete–ECC beams. Methodology/approach: Experimental and FE analyses were conducted on the shear performance of 36 webless reinforced concrete–ECC composite beams with varied concrete strengths, shear-to-span ratios, ECC thicknesses, and interfacial treatments between the layers. Results: The results indicate that the effect of the shear-to-span ratio is greater, the effect of the form of interface treatment is smaller, the effect is weakened after the ECC thickness is greater than 70 mm (i.e., the ratio of the replacement height to section height is approximately 0.35), the shear resistance is reduced when the hoop rate is greater, and the best shear resistance is obtained when the ECC 70 mm thickness and the hoop rate of 0.29% are used together. Conclusions: This study can serve as a technical reference for enhancing the problems of low durability and inadequate fracture control performance of RC beams in shear and as a guide for structural design research. Full article

(This article belongs to the Special Issue Smart Materials: Next Generation in Science and Technology)

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14 pages, 4891 KiB

Open AccessArticle

Study of Effective Stress Intensity Factor through the CJP Model Using Full-Field Experimental Data

by Alonso Camacho-Reyes, Jose Manuel Vasco-Olmo, Giancarlo Luis Gómez Gonzales and Francisco Alberto Diaz

Materials 2023, 16(16), 5705; https://doi.org/10.3390/ma16165705 - 20 Aug 2023

Cited by 1 | Viewed by 760

Abstract

In this work, the Christopher–James–Patterson crack tip field model is used to infer and assess the effective stress intensity factor ranges measured from thermoelastic and digital image correlation data. The effective stress intensity factor range obtained via the Christopher–James–Patterson model, which provides an [...] Read more.

In this work, the Christopher–James–Patterson crack tip field model is used to infer and assess the effective stress intensity factor ranges measured from thermoelastic and digital image correlation data. The effective stress intensity factor range obtained via the Christopher–James–Patterson model, which provides an effective rationalization of fatigue crack growth rates, is separated into two components representing the elastic and retardation components to assess shielding phenomena on growing fatigue cracks. For this analysis, fatigue crack growth tests were performed on Compact-Tension specimens manufactured in pure grade 2 titanium for different stress ratio levels, and digital image correlation and thermoelastic measurements were made for different crack lengths. A good agreement (~2% average deviation) was found between the results obtained via thermoelastic stress analysis and digital image correlation indicating the validity of the Christopher–James–Patterson model to investigate phenomena in fracture mechanics where plasticity plays an important role. The results show the importance of considering crack-shielding effects using the Christopher–James–Patterson model beyond considering an exclusive crack closure influence. Full article

(This article belongs to the Special Issue Computational and Experimental Mechanics of Engineering Materials and Structures)

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27 pages, 7066 KiB

Open AccessFeature PaperArticle

Properties of Ramie (Boehmeria nivea (L.) Gaudich) Fibers Impregnated with Non-Isocyanate Polyurethane Resins Derived from Lignin

by Vincentius Yolanda Angger Raditya, Muhammad Adly Rahandi Lubis, Rita Kartika Sari, Petar Antov, Seng Hua Lee, Lubos Kristak, Efri Mardawati and Apri Heri Iswanto

Materials 2023, 16(16), 5704; https://doi.org/10.3390/ma16165704 - 20 Aug 2023

Cited by 1 | Viewed by 1305

Abstract

The textile industries need an alternative to cotton since its supply is unable to keep up with the growing global demand. The ramie (Boehmeria nivea (L.) Gaudich) fiber has a lot of potential as a renewable raw material but has low fire-resistance, [...] Read more.

The textile industries need an alternative to cotton since its supply is unable to keep up with the growing global demand. The ramie (Boehmeria nivea (L.) Gaudich) fiber has a lot of potential as a renewable raw material but has low fire-resistance, which should be improved. In this work, the objectives were to investigate the characteristics of lignin derived from black liquor of kraft pulping, as well as the properties of the developed lignin-based non-isocyanate-polyurethane (L-NIPU), and to analyze ramie fiber before and after impregnation with L-NIPU. Two different formulations of L-NIPU were impregnated into ramie fiber for 30, 60, and 90 min at 25 × 2 °C under 50 kPa. The calculation of the Weight Percent Gain (WPG), Fourier Transform Infrared Spectrometer (FTIR), Rotational Rheometer, Dynamic Mechanical Analyzer (DMA), Pyrolysis Gas Chromatography Mass Spectrometer (Py–GCMS), Universal Testing Machine (UTM), and hydrolysis test were used to evaluate the properties of ramie fibers. The result showed that ramie fiber impregnated with L-NIPU produced higher mechanical property values and WPG than non-impregnated ramie fiber. There is a tendency that the longer impregnation time results in better WPG values, FTIR intensity of the urethane group, thermomechanical properties, crystallinity, and mechanical properties of ramie fiber. However, the use of DMC and HMT cannot replace the role of isocyanates in the synthesis of L-NIPU because it produces lower heat resistance than ramie impregnated using pMDI. Based on the results obtained, the impregnation of ramie fiber with L-NIPU represents a promising approach to increase its wider industrial application as a functional material. Full article

(This article belongs to the Special Issue Valorization of Lignocellulosic Biomass for Functional Materials)

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21 pages, 12055 KiB

Open AccessArticle

Flexural Strengthening of Stone Masonry Walls Using Textile-Reinforced Sarooj Mortar

by Abdullah Hilal Al-Saidy, Manal Al-Busaidi, Sherif El-Gamal and Kazi Md Abu Sohel

Materials 2023, 16(16), 5703; https://doi.org/10.3390/ma16165703 - 20 Aug 2023

Cited by 1 | Viewed by 829

Abstract

The majority of historical buildings and structures in Oman were built using unreinforced stone masonry. These structures have deteriorated due to ageing of materials, environmental degradation, and lack of maintenance. This research investigates the physical, chemical, and mechanical properties of local building materials [...] Read more.

The majority of historical buildings and structures in Oman were built using unreinforced stone masonry. These structures have deteriorated due to ageing of materials, environmental degradation, and lack of maintenance. This research investigates the physical, chemical, and mechanical properties of local building materials and the results of an experimental study on the out-of-plane bending effectiveness of an innovative strengthening method applied to existing masonry walls. The technique consists of the application of a basalt textile-reinforced sarooj mortar (TRM) on one face of the walls. Bending tests of masonry wall samples (1000 mm width, 2000 mm height, and 350 mm depth) were carried out on one unreinforced specimen and three different cases of reinforced specimens. The performance of unreinforced and reinforced specimens was analyzed and compared. The strengthened specimens were able to resist moments of out-of-plane bending 2.5 to 3 times greater than those of unreinforced specimen (160–233% increase). Moreover, the strengthened walls were able to sustain higher deformations (deflections) than the unreinforced specimen ranging from 20 to 130%. The results showed that using TRM was effective for the out-of-plane strengthening of stone masonry using a local material (sarooj) that is compatible with existing stone masonry building materials. Full article

(This article belongs to the Special Issue Methodology of the Design and Testing of Composite Structures)

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13 pages, 5725 KiB

Open AccessArticle

Measurement of Creep Stress Exponent of TC17 Titanium Alloy by Nanoindentation Method at Room Temperature

by Fagui Li, Xiyu Chen, Yuannan Wang, Guolong Zhao and Yinfei Yang

Materials 2023, 16(16), 5702; https://doi.org/10.3390/ma16165702 - 20 Aug 2023

Cited by 1 | Viewed by 765

Abstract

The creep stress exponent is commonly employed to characterize the deformation mechanism during the steady-state creep stage, serving as an indicator of creep behavior. The creep phenomenon of high melting point metallic materials is not obvious at room temperature. However, the nanoindentation method [...] Read more.

The creep stress exponent is commonly employed to characterize the deformation mechanism during the steady-state creep stage, serving as an indicator of creep behavior. The creep phenomenon of high melting point metallic materials is not obvious at room temperature. However, the nanoindentation method proves suitable for investigating the creep properties of metallic materials under such conditions. Consequently, this paper places emphasis on measuring the creep stress exponent of TC17 titanium alloy at room temperature using the load preservation stage of the nanoindentation method with a constant loading rate. In order to investigate the effects of loading rate and maximum load on the experimental results, different loading rates were applied to the diamond Berkovich indenter to reach different maximum loads. The indenter was held under the maximum load for a duration of 360 s, and the relationship between the indentation strain rate and indentation stress during the holding process was used to obtain the creep stress exponent of the material at room temperature. The findings indicate that within the loading rate range of 1.25 to 15 mN/s and maximum load range of 50 to 300 mN, the influence on the experimental results is insignificant. Ultimately, the distribution range of the creep stress exponent for TC17 titanium alloy at room temperature was measured to be 8.524–8.687. Full article

(This article belongs to the Special Issue Advances in the Machined Surface Integrity in Manufacturing Process of Materials)

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11 pages, 1770 KiB

Open AccessArticle

Mathematical Model of Propagation of an Aerosol Created by an Impulse Method in Space

by Olga Kudryashova, Sergei Sokolov and Alexander Vorozhtsov

Materials 2023, 16(16), 5701; https://doi.org/10.3390/ma16165701 - 20 Aug 2023

Viewed by 870

Abstract

When developing neutralization systems for harmful agents, it is necessary to understand the mechanisms of the formation and evolution of an aerosol cloud in a closed or open space. Effective decontamination with aerosol clouds is provided by a rather high particle concentration and [...] Read more.

When developing neutralization systems for harmful agents, it is necessary to understand the mechanisms of the formation and evolution of an aerosol cloud in a closed or open space. Effective decontamination with aerosol clouds is provided by a rather high particle concentration and dispersion in an open space or on contaminated surfaces. This paper considers neutralization systems based on pulsed powder aerosol generators. It is shown that an aerosol cloud consisting of micron- and submicron-sized particles appears for several seconds after spraying. A further evolution of the aerosol cloud in a room is associated with the gravitational settling, diffusion, and coagulation of particles and their settling on the walls and ceiling. In the case of an open space or a ventilation system in a room, the evolution of the aerosol cloud is affected by the airflow. The main purpose of this paper is to determine the most important parameters and critical conditions of pulsed aerosol generation. A mathematical model is, thus, proposed for pulsed aerosol generation, and its parametric study is conducted in the most typical conditions. The purpose performance predicted by the model is the mass concentration of aerosol particles in the air and on surfaces, depending on the time of particle spraying and dispersion. Full article

(This article belongs to the Special Issue Fabrication, Characterization and Application of High-Energy Material (Volume II))

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26 pages, 26586 KiB

Open AccessArticle

A Study of Molecular Dynamic Simulation and Experimental Performance of the Eucommia Ulmoides Gum-Modified Asphalt

by Simeng Yan, Naisheng Guo, Zhaoyang Chu, Xin Jin, Chenze Fang and Sitong Yan

Materials 2023, 16(16), 5700; https://doi.org/10.3390/ma16165700 - 19 Aug 2023

Viewed by 835

Abstract

In recent years, eucommia ulmoides gum (EUG), also known as gutta-percha, has been extensively researched. Molecular dynamic simulations and experiments were used together to look at how well gutta-percha and asphalt work together and how gutta-percha-modified asphalt works. To investigate the gutta-percha and [...] Read more.

In recent years, eucommia ulmoides gum (EUG), also known as gutta-percha, has been extensively researched. Molecular dynamic simulations and experiments were used together to look at how well gutta-percha and asphalt work together and how gutta-percha-modified asphalt works. To investigate the gutta-percha and asphalt blending systems, the molecular models of asphalt and various dosages of gutta-percha-modified asphalt were set up using Materials Studio (MS), and the solubility parameters, intermolecular interaction energy, diffusion coefficient, and mechanical properties (including elastic modulus, bulk modulus, and shear modulus) of each system were calculated using molecular dynamic simulations at various temperatures. The findings indicate that EUG and asphalt are compatible, and sulfurized eucommia ulmoides gum (SEUG) and asphalt are more compatible than EUG. However, SEUG-modified asphalt has better mechanical properties than EUG, and the best preparation conditions are 10 wt% doping and 1 h of 180 °C shearing. Primarily, physical modifications are required for gutta-percha-modified asphalt. Full article

(This article belongs to the Special Issue Asphalt Mixtures and Pavements Design)

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10 pages, 5201 KiB

Open AccessArticle

Influence of β-Stabilizer Element on Microstructure and Mechanical Behavior of Porous Titanium Alloy Synthesized by Liquid Metal Dealloying

by Artem Okulov, Stefan Berger and Ilya Okulov

Materials 2023, 16(16), 5699; https://doi.org/10.3390/ma16165699 - 19 Aug 2023

Viewed by 896

Abstract

The metallic implant materials for load-bearing applications typically possess a significantly higher stiffness when compared with that of human bone. In some cases, this stiffness mismatch leads to a stress-shielding effect and eventual loosing of the implant. Porous metallic materials are suitable candidates [...] Read more.

The metallic implant materials for load-bearing applications typically possess a significantly higher stiffness when compared with that of human bone. In some cases, this stiffness mismatch leads to a stress-shielding effect and eventual loosing of the implant. Porous metallic materials are suitable candidates to overcome this problem. In this study, we synthesized low modulus open porous TiFe alloy by liquid metal dealloying of the precursor Ti_47.5Fe_2.5Cu₅₀ (at.%) material in liquid Mg. Upon liquid metal dealloying, Cu was selectively dissolved from the precursor, and the remaining Ti and Fe elements were reorganized into a bicontinous porous structure. The synthesized TiFe alloy is composed of α-titanium and β-titanium phases. The average measured ligament size is in the micrometer range. It was found that a higher dealloying temperature leads to a pronounced coarsening of the microstructure. The open porous TiFe alloy possesses a low elastic modulus of about 6.4–6.9 GPa. At the same time, its yield strength value reaches about 185 MPa due to the α + β microstructure. Its attractive mechanical properties for biomedical applications, together with its open porous structure, indicate the potential of porous TiFe alloys to be used as implants. Full article

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15 pages, 3895 KiB

Open AccessArticle

Basic Properties of MgAl-Mixed Oxides in CO₂ Adsorption at High Temperature

by Dylan Chaillot, Vincent Folliard, Jocelyne Miehé-Brendlé, Aline Auroux, Liva Dzene and Simona Bennici

Materials 2023, 16(16), 5698; https://doi.org/10.3390/ma16165698 - 19 Aug 2023

Cited by 1 | Viewed by 877

Abstract

The increase of consciousness towards global warming and the need to reduce greenhouse gas emissions lead to the necessity of finding alternative applications based on easy-to-use materials in order to control and reduce global CO₂ emissions. Layered Double Hydroxides (LDHs) and LDH-derived [...] Read more.

The increase of consciousness towards global warming and the need to reduce greenhouse gas emissions lead to the necessity of finding alternative applications based on easy-to-use materials in order to control and reduce global CO₂ emissions. Layered Double Hydroxides (LDHs) and LDH-derived materials are potentially good adsorbents for CO₂, thanks to their low cost, easy synthesis, high sorption capacity, and surface basicity. They have been intensively studied in CO₂ capture at high temperature, presenting variable sorption capacities for MgAl LDHs with the same composition, but prepared under different synthesis conditions. The ambient temperature coprecipitation synthesis method is an attractive one-step procedure to synthesize LDHs under mild conditions, with low energy consumption and short synthesis time. The present study is based on the synthesis and characterization of hydrotalcites by a mild-conditions coprecipitation process and the production of derived mixed oxides to be used as CO₂ adsorbents. A critical comparison to similar materials is reported. Moreover, the effect of the surface basicity of the derived mixed oxides (measured by adsorption calorimetry) and the CO₂ sorption capacity are discussed, showing a linear correlation between the amount of weak and very strong basic sites and the CO₂ adsorption behavior. Full article

(This article belongs to the Special Issue Synthesis, Modification and Utilization of Porous Materials as Adsorbents, Catalysts and Catalyst Supports)

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Materials, Volume 16, Issue 16 (August-2 2023) – 225 articles

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